This PDF file contains the front matter associated with SPIE Proceedings Volume 12957, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Metal Oxide Resist (MOR) is one of the promising resists for High-NA EUV lithography. However since the pattern pitch is getting smaller, pattern collapse issue has been getting sever problem. We developed Organic Dry Development Rinse (O-DDR) process as extension for wet development to prevent the pattern collapse issue without using any special equipment. O-DDR process has been demonstrated the capability to prevent MOR pattern collapse and expand process window with pitch 32nm pillar and pitch 28nm line and space in EUV lithography . In this paper, we introduce O-DDR process concept and performance for MOR patterning.

The study investigates a new platform of PFAS-free PAGs and evaluates their lithographic efficiency in comparison to PFAS-containing counterparts in multiple model photoresists, including both negative and positive tones, across a broad range of optical exposure wavelengths. PFAS-free photoresists materials demonstrate comparable / superior lithographic performance in resolution, depth-of-focus (DOF), and exposure latitude (EL) compared with their non-degradable counterparts.

EUV lithography has been realize to use the mass production for 5nm logic device manufacture and beyond and semiconductor manufacturing plants that introduce EUV exposure system are being built or planned around the world. Therefore, the greatest interest of the EUV lithography is sub 10nm resolution patterning capability using high NA optics system. However, EUV chemically amplified resists (CARs) have had big problems about pattern defects due to stochastic effects from photon shot noise and acid diffusion blur less than 13nm HP. There is a trade-off relationship between resolution, line width roughness (LWR), and sensitivity (RLS trade-off). The RLS trade-off problems have come to a head with the progress of pattern miniaturization. The improvement of LWR and sensitivity without degrading the resolution is technically difficult because of acid diffusion and stochastic effect. Moreover, etching durability of CARs are also gradually surfaced as an issue due to reducing film thickness to prevent pattern collapse. The development of a novel platform for high resolution patterning becomes important. Currently, some of the new resist platform have been investigated and metal oxide resist and dry film resist were particularly achieved good patterning performance and etching durability as negative type resist by using metal component in the systems. On the contrary, performances of metal containing positive type resist by treating metal infiltration have not been sufficient to compare with the negative type resists. Sensitivity of non-CAR resists have a limitation by lack of the reaction probability because of only one reaction per photon at maximum. Therefore, including high concentration of EUV absorbing metal component, using chemically amplified reaction or other sensitivity enhancement techniques are necessary to meet the sensitivity requirement for high NA EUV resist. Previously, we proposed a positive tone organometal chemically amplified resist by making dissolution contrast though chain scission and polarity change to develop for butyl acetate. However, sensitivity and resolution were not sufficient as a photoresist for high NA EUV lithography. Although performance can be improved by modification of some structures, at first, we explored a way to significantly improve sensitivity by using PS-CAR process and new acid generator which can change the structure to UV sensitive one by EUV exposure only exposed area because of an aiming to reduce massive power consumption of EUV lithography.

One of the key steps in the pattern formation chain of extreme ultraviolet (EUV) lithography is the development process to resolve the resist pattern after EUV exposure. The traditional development process might be insufficient to achieve the requirements of ultra-high-resolution features with low defect levels. The aim of this paper is to establish a process to achieve a good roughness, a low defectivity at a low EUV dose, and capability for extremely-high-resolution for high numerical aperture (NA) and hyper-NA EUV lithography. A new development method named ESPERT™ (Enhanced Sensitivity develoPER Technology™) has been introduced to improve the performance of metal oxide-resists (MOR). ESPERT™ as a chemical super resolution technique effectively apodized the MOR chemical image, improving chemical gradient (higher exposure latitude (EL)) and reducing scums (fewer bridge defects). This new development method can also keep the resist profile vertical to mitigate the break defects. The performances of the conventional development and ESPERT™ were evaluated and compared using 0.33 NA EUV, 0.5 NA EUV, and electron beam (EB) exposures, for all line-space (LS), contact hole (CH), and pillar (PL) patterns. Using 0.33 NA EUV scanners on LS patterns, both bridge and break defects were confirmed to be reduced for all 32-nm-pitch, 28-nm-pitch, 26-nm-pitch LS patterns while reducing the EUV dose to size (DtS). In the electrical yield (1 meter length) test of breaks/bridges of 26-nm pitch structures, ESPERT™ reduced EUV dose while its combo yield was almost 100% over a wide dose range of 20mJ/cm². For CH patterns, in the case of 32-nm-pitch AEI (after etch inspection), EL was increased 7.5% up to 22.5%, while failure free latitude (FFL) was widened from 1-nm to 4-nm. A 16-nm-pitch LS pattern was successfully printed with 0.5 NA tool, while a 16-nm-pitch PL and an 18-nm-pitch CH patterns were also achieved with an EB lithography by ESPERT™. With ESPERT™, there was no pillar collapse observed for 12-nm half-pitch PL by 0.5 NA and 8-nm half-pitch PL by EB. With all the advantages of having a high exposure sensitivity, a low defectivity, and an extremely-high-resolution capability, this advanced development method is expected be a solution for high-NA EUV towards hyper-NA EUV lithography.

High numerical aperture (NA) EUV lithography is considered as the most-promising candidate for next generation lithography protocol that will play a crucial role in meeting the demand on the enhanced semiconductor performance and productivity. While this technology enables the fabrication of sub-10 nm patterns, the increased NA has posed challenges, such as reduced depth of focus and narrower process margins. To overcome these hurdles, it is essential to apply thinner resist films while ensuring that the resulting small patterns maintain sufficient physical and chemical durability. Moreover, considering that thinner films absorb fewer photons, the resist molecular structure should be designed to compensate sensitivity burdens. Here, an approach has been proposed to enhance sensitivity by accelerating the solubility change of a well-known tinbased nanocluster resist. To accomplish this goal, it is important to increase not only the number of secondary electrons but also reaction sites and promote radical-based chemical reactions. We aimed at experimentally validating this concept by utilizing elements with high EUV absorbance and highly reactive functional groups with tin radicals. As a model resist, we chose a tin-oxo cage material consisting of a divalent cation containing 12 tin atoms and two counter anions. Our findings indicate that the introduction of unsaturated groups capable of building bridging bonds with radicals leads to fast solubility change at a lower exposure dose, thus enhancing sensitivity. This research offers a promising direction for the development of resists tailored for High NA EUV lithography.

Airborne molecular contaminants (AMCs) in the cleanroom have been known to impact the performance of photoresist materials. Here, we investigate the effect of the environment composition during post-exposure delay (PED) on metal oxide resists (MOR). We applied specific environments during a fixed PED time and measured the impact of each condition on the printed L/S patterns by measuring the change in the final critical dimension (CD) in each case compared to a reference control. We performed chemical analysis to elucidate which chemical changes take place in the resist under the conditions that induced the largest CD changes. Our results suggest that the magnitude of the CD change after a fixed PED time depends on two main variables: the concentration of contaminants and the humidity of the environment. The chemical analysis after a PED in the presence of contaminants and humidity revealed that extra ligand cleavage takes place under these conditions compared to the reference non-delayed conditions. The results show that deviations from the target CD in MOR can be prevented by having control over humidity, contaminant levels, and PED time during processing. Furthermore, new optimized formulations designed to hinder extra chemical reactions during PED show a stable CD even when the PED was applied in environments with humidity and contaminants.

Chemically amplified resists (CARs) have been widely used for lithography of semiconductors. To suppress stochastic defects, the increase in the number of absorbed photons is essential and the increase in acid generator concentration is needed to capture all the generated electrons. Therefore, the effect of the acid generators on the dissolution of the resist increased. In this study, radiation-induced decomposition of acid generator and dissolution of poly(4-vinylphenol) (PHS) containing 30 wt% of acid generators was investigated using pulse radiolysis, γ radiolysis, quartz crystal microbalance (QCM) methods. TPS-TF was used as the reference structure, and three acid generators with different anionic and cationic structures were prepared, respectively. The structure of the cation was found to affect the decomposition product ratio of the final product. Both cation and anion structures were found to affect the dissolution behavior of the PHS films.

Chemically amplified photoresists (CAR) are the leading photoresists used in Extreme Ultraviolet (EUV) lithography. Chemical stochastics are an issue for defectivity and roughness due to the distribution of the multiple components of the resist. It is believed that the non-random distribution of components occurs primarily during the spin coating process, as the resist dries, and the solvent concentration is reduced. Inhibiting the unwanted chemical segregation can be controlled by increasing the evaporation rate during the spin coating process. In addition to reducing the chemical segregation of the resist through the spin coating process, it is important to compare between different resist formulations for their risk of chemical segregation. We will show accelerated testing processes using solvent vapor annealing to help identify the relative risk of segregation between multiple commercial photoresists.

Extreme ultraviolet lithography (EUVL) enables integrated circuit (IC) industry to manufacture chips with increased transistor density per volume unit, so the Moore’s law remains true to date. To support the endless requirement of reducing critical dimension (CD), chemically amplified resist (CAR) has been designed to address the resolution, line width roughness, and sensitivity (RLS) in nanoscale level. However, a good Litho performance from an EUV photoresist may not always be transferred into a good etch performance, limiting the stochastic defects after patten transfer is the key to achieve a good after etch inspection (AEI) defectivity. In this paper, we report the EUV photoresist design strategies to acquire good AEI defectivity with the understanding of CAR’s property in a defined pattern transfer scheme with special focus on small molecule in photoresist. The CAR’s Litho performance and the corelated etch performance will be discussed, the component etch rate and its correlation to photoresist etch performance will be covered.

In this study, we focus on examining the stability of Al-based inorganic-organic hybrid thin films deposited through the molecular atomic layer deposition (MALD) process in ambient environment. Our observations reveal an initial reduction in material thickness within the first 3 days, followed by a period of stability. XPS analysis is employed to further investigate the chemical alternations in the aged Al-based hybrid thin films, revealing an increase in C=O species as well as overall oxygen content in the material. We also evaluate the effects of atmospheric exposure on the sensitivity of the Al-based hybrid thin films using electron flood exposure. This study aims to enhance the understanding of the stability of a vapor-phase synthesized hybrid thin film system for advanced resist applications.

EUV photon-generated primary and secondary electrons, produced by a cascade of inelastic scattering events, have a wide range of energies and drive EUV patterning by initiating chemical transformations. To study electron-induced chemistry we exposed photoresist films to an electron beam varied from 20 to 80 eV. Chemical transformations were characterized using a residual gas analyzer, FTIR, and ellipsometry. Total outgassing was determined for key fragments and compared to film thickness changes via ellipsometry and FTIR bond structure changes. Estimates of electron penetration depth and reaction efficiency (bonds broken per electron) will be presented.

For the advancement of lithography, the resist materials and processes are the most critical issue in the microfabrication of semiconductors. Especially in the sub-20nm half pitch resolution region, the development process of resist materials is of particular importance from the viewpoint of reducing the line width roughness (LWR) and stochastic defects. In this study, a quartz crystal microbalance (QCM) method was used to investigate the dissolution dynamics of poly(4-hydroxystyrene-co-methacrylic acid) (PHSMA) films in tetraalkylammonium hydroxide aqueous solutions. The PHSMA film showed a characteristic dissolution kinetics in tetraalkylammonium hydroxide aqueous solutions, which was not observed for poly(4-hydroxystyrene) film.

Augmented reality glasses offer the potential to seamlessly integrate digital information into the world to enable users to maintain a strong situational awareness of the physical world while interacting with content. This awareness is particularly important in mobile computing scenarios, as users move through uncontrolled environments. For users to be comfortable wearing AR glasses in public spaces and for extended durations, they need to be in a compact, lightweight, and socially acceptable form factor, such as today’s prescription glasses. At the same time, it is helpful to provide users a large field-of-view image with high image quality—placing strong demands on optical architectures and underlying materials. We’ll discuss how material properties and processes constrain the performance of AR glasses, and the potential to enable higher performance in a smaller form factor. We’ll describe considerations for optical waveguide substrates, coatings, and patterning processes, with discussion of impacts to both display and sensor systems. Finally, we’ll highlight areas for materials and process improvements that could have large positive impacts on the AR glasses field.

Per- and poly-fluoroalkyl substances (PFAS) have come under increased scrutiny because all members of this class of compounds exhibit very high environmental persistence (vP), and some exhibit toxicity (T) and/or bioaccumulation (B) potential. Because of these attributes, PFAS chemicals are being scrutinized by regulatory authorities for restrictions on use and releases to the environment. At the same time, PFAS are crucial components of many process materials used in semiconductor photolithography, to the extent that manufacture of advanced chips is currently not possible without them. While PFAS uses are crucial, the amounts used in these key applications are small relative to global PFAS production and use, a fact that may not be generally known. The purpose of this paper is to provide a quantitative assessment of the amount of PFAS used in semiconductor photolithography, and to present a mass balance model for the disposition of these materials into the different waste streams. This model allows identification of key areas for prioritized action, including the need for targeted research and development.

The decomposition of poly(phthalaldehyde) with a photoacid generator can be used as dry-develop photoresist, where the exposed film depolymerizes into small molecules to allow the development of features via controlled vaporization. Higher temperatures enabled shorter dry-development times, but also promote faster photoacid diffusion that compromised pattern fidelity. Trihexylamine was used as a base quencher to counteract acid diffusion in a phthalaldehyde-propanal co-polymer photoresist. The propanal co-monomer in the polymer improves the vaporization rate because it has a higher vapor pressure than phthalaldehyde. The dry-development of 4μm features was achieved with no appreciable residue.

With the adoption of extreme ultraviolet lithography (EUVL) to decrease microelectronic device dimensions, recent photoresist research has focused on the development of next generation metal-organic resist materials. To enhance lithographic capabilities and mitigate common drawbacks seen from traditional solvent based processes like spin coating and solution phase development, interest has shifted towards solvent-free “dry” deposition and development. These dry techniques can obviate extra processing steps, significantly reduce the amount of solvent waste generated, and even allow for reduced defect density and higher resolution. The process described herein avoids the use of solvents, and ultimately many issues associated with solvents, by depositing metal-organic resists using atomic/molecular layer deposition (ALD/MLD) and developing them using a selective thermal dry etching process. The low temperature (e.g., 100-120°C) thermal development conditions used in this study are notable in the context of lithography processes, as the high temperatures required in other dry etching processes can be difficult to implement in nanofabrication processes. Our previous work has focused on using amorphous zinc-imidazolate (aZnMIm) films in an all-dry resist technology, achieving resolution down to 22nm. Here, we explore the role of temperature and time on dry development and examine pattern transfer into silicon substrates. Preliminary pattern transfer experiments suggest that an etch selectivity of at least 7:1 exists for electron-beam treated aZnMIm over silicon using a pseudo-Bosch plasma etch. Our findings demonstrate the feasibility of dry development at lower temperatures and times and suggest potential for aZnMIm as a high-resolution resist for nextgeneration lithography.

The main challenge in developing a suitable EUV photoresist, particularly for high Numerical Aperture (NA) EUV lithography anticipated for late 2024, lies in the Resolution, Line Width Roughness, and Sensitivity (RLS) trade-off. PiBond has been actively addressing this challenge by developing silicon photoresist (SiPR) based on chemically modified HSQ siloxane chemistry, consisting of a single polymer component. This resist, a non-metal negative tone, high Si-containing, employs the industry-standard TMAH developer. Previously, we achieved a resolution of 32nm pitch with a dose of 170mJ/cm² and a Line Width Roughness (LWR) of 5.3nm. In this study, we synthesized a novel chemically modified HSQ-type siloxane resist to enhance RLS characteristics, assessing its performance using both Electron Beam Lithography (EBL) and EUVL. Utilizing the EUV Interference Lithography tool at PSI, we obtained a 28nm pitch resolution with an improved LWR of approximately 3.2nm, while controlling the dose-to-size to about 120mJ/cm². Furthermore, by employing a suitable silicon hard mask underlayer developed in-house, we further enhanced sensitivity by 24% at 28nm pitch and 38% at 30nm pitch resolution. Crucially, we established correlations between EBL and EUV for our SiPR, leveraging the accessibility of EBL compared to EUV tools. Leveraging these correlations, we effectively utilized EBL to investigate the newly synthesized resist and optimize processing conditions. Our findings demonstrate the significant impact of both resist functionalization and processing conditions on the final lithography performance.

Roll-to-Plate (R2P) large-area Nanoimprint Lithography (NIL) is a leading technology to replicate complex textures onto various substrate materials. It combines the accuracy of UV imprinting with large-area display manufacturing methods. This is a significantly cost-effective manner to perform micro and nano surface patterning for a plurality of display optics applications, including emerging technologies, such as Augmented Reality (AR) waveguides. Even though NIL technology is advancing to comply with the strict quality requirements of waveguide manufacturing, many challenges still remain. Hereby, we address different aspects that need to be considered to make R2P-NIL a viable mass manufacturing method for AR optics, focusing on scalability and quality. We discuss the potential for scalable waveguide manufacturing, through waveguide upscaling for large-area NIL (Gen5 size, 1100 mm x 1300 mm), in combination with the usage of square high refractive index glass substrates (in contrast to the usual round wafers). By making optimal use of this combination, we demonstrate that 480 waveguides can be manufactured in one imprint cycle. Additionally, of equal importance to scalability, high waveguide quality is achieved through the use of high refractive index materials, maintaining of imprint fidelity, and control of the residual layer thickness and its variation. We show that, using the R2P-NIL technology of Morphotonics to replicate AR waveguides, imprint fidelity of binary, blazed and slanted gratings are retained over repeating imprint cycles.

Advancements in Augmented Reality/Virtual Reality technology have increased the demand for methods of printing three-dimensional structures. In this contribution we will talk about these technology improvements applied to Surface Relief Gratings – considering photoresists and Nanoimprint layer materials for making a grating, as well as Gap Fill materials for adjusting the refractive index (RI). We will discuss in detail a developed positive tone, i-line photoresist formulation which has been developed for greyscale lithography. We will introduce a range of nanoimprint materials and show the developments of our Ink Jet Printable (IJP) low absorption, high RI gap fill formulations. These innovative formulations are made possible by utilizing a unique precursor and employing special process conditions for optical grating applications.

Breakthroughs in holographic optical devices frequently rely on advances in high-refractive-index photopolymer materials (HRIPs). While significant progress has been made in the pursuit of HRIPs, additional considerations have prevented broad application of photopolymerization-based materials for fabricating high-performance holographic gratings. To address the deficiency of suitable high-refractive-index monomers for holographic recording, our recent works were conducted from two main aspects, which are (1) monomer synthesis to improve the theoretical refractive index contrast between photopolymer and matrix (or binder), and (2) formulation manipulation for improving segregation degree between photopolymer and matrix (or binder). We have explored several synthetic approaches to obtain high-refractive-index acrylate monomers (nD=1.6) of high miscibility with matrix, multifunctional low-viscosity, high-refractive-index thiol-ene and thiol-yne monomers (nD=1.6). Combining with polyurethane matrix (binder) with a refractive index of 1.48, these monomers exhibit a high theoretical peak-to-valley index contrast of more than 0.12. To fully utilize the high theoretical index contrast, thiol-ene click chemistry in combination with a linear functionalized polymer binder was explored to achieve a high refractive index modulation(peak-to-mean) close to 0.04. Meanwhile, in the thiol-ene formulations, a variety of chemical modification methods, which can be readily translated into other material systems, were proposed, and studied to manipulate the rates of reaction and diffusion processes during holographic recording to optimize the refractive index modulation. The dramatic difference of achievable refractive index modulation in similar thiol-ene formulations with close theoretical index contrast was observed in such study. The difference underscores the importance of customized strategies and systematic formulation manipulation for achieving high-performance holographic photopolymers.

With the advent of novel optical and photonic devices such as Augmented Reality (AR), and Mixed Reality (MR), there is renewed interest in Nanoimprint Lithography (NIL) technology as a cost-effective approach to manufacture key performance enhancing components for these devices, such as surface relief gratings (SRGs) for waveguides. We have developed multiple types of resists for use in NIL for making Surface Relief Gratings (SRGs) for waveguides for AR and MR devices. This paper will discuss the NIL performance of our resists such as high refractive index functional NIL resists, resists for NIL-Etch process as we11 as resists for Bi-layer NIL-Etch approach for patterning high aspect ratio structures. We wi11 discuss various material properties and performance of the NIL resists in NIL process.

Optics is increasingly important in modern life, and advances in nanostructure-based flat optical devices hold great promise for revolutionary new opportunities in the display space. Augmented Reality (AR) are expected to enable the next ubiquitous computing and communication platform. Augmented Reality, especially, is a transformational new category of display that allows for the overlay of timely, location-based, or other useful information on the user’s natural view of the surrounding world. The Photonics Platforms group at Applied Materials is enabling higher brightness, thinner and lighter-weight optical systems with precise wavefront engineering to make possible novel optical devices. We have leveraged Applied Materials’ materials engineering expertise to develop a platform for the precision fabrication of nanostructured optical devices on 300mm glass wafers, as well as metrology, optical performance characterization, and back-end assembly of these devices. With this platform, we are producing top of the art waveguide combiners for AR applications and optical metasurfaces for multi-functional wavefront control in the near infrared.

The organic non-chemically amplified resist (non-CAR) materials have been developed for fine pitch contact hole patterning process to remove the acid blur of conventional chemically amplified resist (CAR) system, but non-CAR materials usually show lower contrast and sensitivity compared to conventional CAR materials, so additional improvements are needed for practical application. In this study, we developed new platforms of EUV PTD resist materials to overcome these limitations and enable fine pitch C/H patterning. The main target of our study is to reduce acid blur and to maintain chemical contrast compared to conventional CAR system by 1) finding better EUV-active structures, or 2) simultaneously generating polarity switching and molecular weight (M.W.) change, or 3) maximizing the M.W. change through the depolymerization. Those new resist materials have confirmed showing equivalent or higher contrast compared to conventional CAR, and also having good resolution in EUV C/H patterning evaluation.

In this work, we introduce the novel resist of ZR13D for high-NA’s generation and report their patterning performance in both ADI and AEI which was compared to the reference resist of ZER02#04DM. Zeon resists have some challenges that LCDU and dose to size are still high and resolution and defectivity should be improved as well. The concreate approaches in order to improve the challenges are that to make scission reaction efficient and to get developability more at exposed area higher in changing both monomers and functional groups. By both effects, Zeon aims to make clear threshold between exposed and un-exposed area and improve low contrast and sensitivity at tight patterns especially. Zeon has developed a new resist (ZR13D, R&D sample) in order to improve their challenges. ZR13D enabled to improve the contrast by EUV when compared to ZER02#04DM significantly. The litho-performance was able to be enhanced on both sensitivity and LCDU by breaking though RLS trade-off. And ZR13D could transfer patterns well in etching process, and then, holes with Zeon resists in AEI enabled to go through until the bottom of SiN substrate without residues. Additionally, ZR13D has maintained the stability of process delay from EUV expose to development process for stitching. It was clarified that ZR13D has the sufficient potential to be utilized at high-NA generation.

We investigate indium nitrate hydrate films as a potential extreme ultraviolet (EUV) resist using electron beam (e-beam) exposure. Indium has an EUV absorption cross-section comparable to tin, the metal element in the state-of-the-art inorganic EUV resists. We choose indium nitrate salts as the metal precursor to minimize residual carbon in the resist. With a calibrated e-beam flood gun, we test the solubility switch in indium nitrate hydrate films as a function of e-beam energy. The resist becomes insoluble upon exposure to the e-beam, exhibiting a negative tone characteristic. The solubility switch occurs for e-beam energy from 500eV down to 92eV, the energy of the EUV photons. Furthermore, to determine the mechanism behind the solubility switch, we study the chemical changes upon e-beam exposure using operando Fourier transform infrared spectroscopy and residual gas analysis. The resists show similar optical contrast and nitric oxide release for three post-application bake (PAB) conditions. The sensitivity and contrast of indium nitrate hydrate are determined from the dose curves obtained using electron beam lithography (EBL) and e-beam flood gun. We obtained an average sensitivity of 226±46μC/cm² from four EBL experiments and a contrast of γ=1.3±0.3. The results from the e-beam flood gun have a sensitivity of 295μC/cm² and γ=1.0. A benchmarking experiment was also performed using an e-beam flood gun on organotin (SnOxo) resist, which has a sensitivity of 165μC/cm² and γ=1.6. The similar characteristics between these two resists indicate that indium nitrate hydrate films hold high promise to be a sensitive EUV resist.

Irresistible Materials is developing a novel photoresist for EUV lithography including high-NA patterning. A major concern for the key research area of high-NA EUV resists is that stochastics in such resist materials can lead both to roughness and defects causing failures, which means high-NA resists remain a priority research area. We are developing a photoresist based on the multi-trigger concept, which seeks to suppress line edge roughness using a new photoresist mechanism, and which is based on molecular rather than polymeric materials to maximize resolution. It also has relatively high EUV absorbance to increase photon capture despite the need for thin films in high-NA due to limited depth-of-focus. By modifying the MTM molecule, crosslinker and PAG, both individually and in combination, we can optimize the reaction rates in the MTR mechanism. Different combinations have been designated Gen 2.1 to Gen 2.6 and show an LWR improvement in Gen 2.4, 2.5 and 2.6 combinations. Here we present the lithographic performance at pitch 28nm dense line/space where 14.1 wide lines were patterned at 59mJ/cm² with an unbiased LER of 2.09nm using a Gen 2.4 resist. We show hexagonal pillar results: pitch 32nm patterned at 42mJ/cm² to obtain a pillar diameter of 16nm with an unbiased LCDU of 2.8nm; and additionally p32 pillars of 16nm diameter were patterned at 74mJ/cm² with an unbiased LCDU of 2.7nm; and of 18.5nm diameter at 82mJ/cm² with an unbiased LCDU of 2.3nm. We also show data which shows using a Gen 2.6 resist can reduce the LCDU of p32 hex pillars by 0.2nm and biased LWR of p28 l/s by 0.3nm compared to a comparable Gen 2.4 resist. Performance improvements such as reduced roughness and defectivity can also be shown to be affected by choices such as underlayer and developer. Additionally, the modification of the developer can be shown to influence the patterning performance of the resist at high resolution.

As Moore’s Law intensifies the demand for higher transistor density, photoresists grapple with challenges posed by shorter wavelengths, especially in speed and stochastic factors. We aim to address these by molecularly optimizing photosensitive materials for precise control at molecular level. Our approach employs sequence-defined polypeptoids, specifically tailored to integrate metal atoms with high EUV absorption, improving both stochastic properties and photoresist sensitivity. Through the sub-monomer peptoid synthesis, we've crafted materials embedding acid-labile groups like tert-butyloxycarbonyl (tBOC) derivatives for solubility switch and 8-hydroxyquinoline derivatives for metal binding. Our in-depth study into peptoid structures and their metal atom positioning offers insights for future lithography techniques. Our ongoing efforts focus on refining these sequences and fine-tuning the exposure process, showcasing our commitment to advancing EUV lithography's capabilities.

Built on the previous study on the negative-tone resist platform, we developed a series of new resists with higher thermal stability enabling PEB temperature above 80°C, with improved pattern quality. Peripheral materials, including developers and under layers, are investigated as well to mitigate pattern collapse and enable patterning line/space below 32nm pitch with LER of 3nm or less. The resists are also capable of printing pillar pattern below 34nm pitch with LCDU below 3nm. A combination of EUV and DSA rectification processes reduces cost of ownership (COO) and attains low roughness with defectivity improvement potentially. The process has great potential in extending resolution below 28nm pitch using 0.33 NA EUV.

Alternative patterning solutions, such as litho-freeze-litho-etch (LFLE) and spacer-based pitch splitting, have been a cornerstone of advanced technology nodes to enable device scaling. The greatest utility comes from the ability to self-align a pitch splitting process; however, traditional spacer-based patterning techniques require the deposition and etch of multiple materials, which reduce throughput and increase manufacturing costs. Anti-spacer technology, on the other hand, enables both self-aligned pitch splitting and high throughput via a single pass track-based process. Here, we present the utility of combining a 193nm immersion anti-spacer process with LFLE to enable the formation of sub-20nm slot contact features for a minimum tip-to-tip cut, with a scaling path to achieve sub-12nm cuts.

To continue the future of dynamic random-access memory (DRAM) manufacturing with EUV and high NA EUV, alternative techniques for nanofabrication are required to reduce the cost and simplify the processes. In this report, we present the results of the development of a single mask solution with 0.33NA EUV lithography for two important layers, bit-line-periphery (BLP) and storage-node-landing-pad (SNLP), in DRAM manufacturing. The methodology has been established for our examination and assessment of the process window (PW) of the critical dimensions (CD) and the defectivity of the SNLP and BLP layers. Based on this methodology, a pitch 34nm DRAM has been optimized with the spin-on metal oxide resist (MOR) and dark field of a binary mask. We obtained the large overlapping PW of CDs (with a depth of focus of 119nm and an exposure latitude of 25% at a dose-to-size of 89.4mJ cm^-2) in the free-defect ranges (20mJ cm^-2). We achieved around ~22% dose reduction using the same processes with spin-on MOR applied to the new design of a low-n mask. We observed a pitch of 32nm SNLP and BLP with a single mask layer due to a low-n mask. Additionally, the process window discovery (PWD) methodology for defect inspection in the large area of SNLP and BLP shows good progress which can be applied for optimized conditions. We believe that our results show the resolution limit of 0.33NA lithography for the single mask print SNLP-BLP and 0.55NA EUV is needed for the next generations of DRAM.

In 2019, finally, extreme ultraviolet (EUV) lithography has been applied to high volume manufacturing (HVM). However, the performance of EUV resist materials are still not enough for the expected HVM requirements, even by using the latest qualifying EUV resist materials. The critical issues were the stochastic, which will be become ‘defectivity’. The analyzing summary of the stochastic factors in EUV lithography was reported, which described 2 (two) major stochastic issues, which are ‘Photon stochastic’ and ‘Chemical stochastic’. In the past, speaking of the stochastic issue was basically considered from low photon number from EUV light source, which means ‘photon shot noise’. It was still critical concerning point, even with recent progress on source power improvement. However, the stochastic issue is not only from them but also from EUV materials and processes, called ‘Chemical stochastic’. The ‘Chemical stochastic’ means caused from resist materials and processes for lithography, materials uniformity in the film, reactive uniformity in the film, and dissolving behavior with the developer. The 1st preliminary results of newly proposed novel formulated organic solvent-based developer for negative-tone development of chemically amplified resist (CAR) with EUV exposure, called CAR EUV-NTD, were reported in last conference, SPIE AL 2023. In this paper, we will also focus on EUV CAR-NTD with New developer, continuously. The mechanisms of new developer behavior for pattern collapse improvement and chemical stochastic reduction. Also, the lithographic performance will also be reported, including underlayer influence.

Advanced AI systems require more exotic packaging solutions to increase performance and manage power loads. Packaging designers not only need increased interconnect density through pitch scaling, but also seek to print this advantage over areas beyond the capability of standard lithography. These demands call for innovations in materials, processes, integrations, and tools for packaging. In a bid to find solutions for finer L/S pattern in redistribution layers, photo-imageable polyimides (PIDs) from different vendors were tested for performance properties (resolution, dose to size, sidewall quality) using direct write exposure methods, and then assessed for compatibility in a dual damascene (DD) integration for FOWLP packaging.

Spin-on Metal Oxide Resist (MOR), Underlayer for EUV lithography and Spin-on Metal Hard Masks (MHM) are being studied for next generation semiconductor processes. Despite the immense potential of these new materials, the industry has paid enormous attention to avoid due to the general concern about trace metal impurities. Purposely introducing these metal-containing materials will inevitably raise alert, especially for track processes involving spin-coat layers that are currently handling primarily high purity organic materials. To address this new application challenge, or more specifically to protect the wafer edges from metal contamination during track processes, the authors have developed wafer Edge Protection Layer (EPL) material. EPL allows the wafer edge protection when the metal-containing coating is applied and the clean stripping with a proprietary solvent, EBR ACE to yield bevel and backside metal-free wafers that could be further processed as usual. This paper provides the key technical details of EPL material, process, and performance, with the aim to offer the industry a practical solution for safely introducing metal-containing spin-coat layers.

The next generation of this technology (using a high-numerical aperture (NA) at 0.55 compared to the present at 0.33) is also currently being prepared and is scheduled to be production ready within the next few years. However, it is well known that the application of higher NA will lead to smaller depth of focus (DOF). The DOF with NA 0.55 systems will reduce to 1/3 of the value that we have in current 0.33 NA systems, i.e. if DOF at NA 0.33 is 100nm then at NA 0.55, DOF will be around 30 to 40nm. At these exposure conditions, wafer surface distortions as an effect of backside defects will become significant concern. In this study, the wafer backside at exactly the same locations detected as where these abnormal CD’s were detected on wafer frontside. And the evidence was shown that the backside defects affected to frontside pattern deformation. Furthermore, it was found that an effective backside cleaning process can mitigate pattern defocus caused by these wafer backside particles.

Pattern collapse emerges as a key factor leading to the failure of photoresist patterns in high-resolution EUV lithography. Its significance escalates as feature sizes decrease and pitches become smaller transitioning to high-NA EUV, potentially leading to challenges with regards to resolution. Collapse arises from capillary forces acting on the resist surface during wafer drying. Consequently, the optimal strategy to mitigate pattern collapse involves eliminating any drying steps post-lithography processing. In this study, we introduce the O-DDR process for spin-on MOR, effectively eliminating capillarity and eradicating the pattern collapse issue without tone inversion. Figure 1 illustrates the O-DDR process, which involves dispensing O-DDR material instead of employing a spin-drying developer, without introducing any extra processing steps. After the dry etching process, we observe that the resist pattern remains intact without any collapse. Furthermore, we conduct an analysis of the O-DDR process, with the goal of expanding the window for a failure-free process with pitch 32nm pillars and pitch 28nm line and space in EUV lithography.

This work will describe the advancement of 193i anti-spacer technology to resolve critical trench dimensions beyond the resolution of single print EUV lithography. A through process performance evaluation will be provided for 13nm trench features from 100nm to 60nm pitch and below. A cursory review of sub-13nm feature scaling and the material factors to enable such trench dimensions will be described. The extension of 193i chemistry and associated layers to intercept EUV patternability requires an understanding of fundamental process parameters and process windows beyond standard practices. Herein, a full study of key anti-spacer parameters and their associated effects on roughness and CDU will be provided. Such variables will include resist film thickness, developer optimization and overcoat dissolution. Lastly, we will outline the ultimate scaling potential of the defined 193i anti-spacer flow and provide future avenues of development to achieve greater scaling at EUV and towards High NA EUV dimensions.

A large screening of underlayer materials for extreme ultraviolet lithography is reported in this work. The main motivation for the screening of functional materials lies in the search for dose reduction and defect mitigation. Some promising results shown in here prove that the usage of functionalized underlayers and primers improves the pattern quality without adding to the complexity of litho processing.

As the industry enters Extreme Ultraviolet (EUV) era, like every technology generation in history, there are constant demands for new materials to solve the emerging challenges accompanying with the continuous scaling effort. Although Chemically Amplified Resist (CAR) resist and conventional tri-layer stack that were established for DUV lithography have been successfully extended to EUV, challenges such as limited etch budget associated with further resist thickness shrinking needed for high Numerical Aperture (NA) EUV, increased line wiggling in SOC layer resulting from larger aspect ratio, etc., are expected to bring CAR EUV lithography to it’s end soon. While new resist platform such as Metal Oxide Resist (MOR) is expected to provide the needed solution for future, other approaches such as further optimization of the underlayer (UL) could also offer an alternate solution by extending the utilization of CAR. In this paper, we explored the possibility of using spin-on metal-oxide hard mask (SOMHM) materials as UL for CAR EUV lithography. We first demonstrated excellent etch selectivity between CAR and SOMHM UL, as well as that between UL and other hard mask layers such as SOC, SiN or SiOx, in P44 pattern transfer study. Further P32 full wafer investigation allowed us to examine the critical parameters such as LER and LWR. Studies of even smaller pitches of 28nm and 24nm showed more advantages of SOMHM UL due to the etch budget limit of CAR. The possibility of simplifying the standard tri-layer stack is also demonstrated by using SOMHM as the direct hard mask for pattern transfer into 60nm SiN.

Extreme Ultraviolet (EUV) lithography has emerged as the state-of-the-art technology for high-resolution patterning in semiconductor manufacturing. However, several challenges persist in the performance of current EUV photoresists, particularly in improving resolution, sensitivity, and line-edge roughness (LER), and local critical dimension uniformity (LCDU). In this study, we describe a novel chemical trimming overcoat process as a highly versatile post-lithography spin-on overcoat to enhance photoresist performance in EUVL, enabling significant dose reduction and z-factor improvement.

Metal oxide resists (MORs) have become one of the most attractive photoresist platforms that allow for high resolution and etch bias of small features while having a robust lithography performance. In this work, we present our study about improving line fidelity and reducing the dose of MOR for line space EUV lithography by applying spin-on underlayers (ULs). It is known that MOR patterning is induced by the activation during exposure and condensation of the active sites. Herein, we discuss the influence of ULs on MOR performance. A series of ULs with various chemistry, thickness, or process conditions were screened with MOR using NXE3400 EUV exposure system to print 14-nm HP line-space features. The results show that the nanobridges and scum can be alleviated, while the remaining resist thickness after development can be improved by up to 20% along with 5 to 10% dose reductions. A comprehensive assessment of the ULs encompassing various chemistries examines coating quality, uniformity, and surface energy. The discussion delves into the correlation between the surface properties including morphology, interaction, etc., and their respective impacts on lithography performance. Lastly, some spin-on ULs produce up to 75% reduction of metal diffusion from the MOR into the underlying layers.

For EUV high NA lithography, current conventional tri-layer and tetra-layer process might face the critical issue both for EUV lithographic performance and pattern etch transfer. Especially since the latest EUV PR including CAR and MOR is very low film thickness around 10nm after development, the bottom under layer such as Si containing hard mask (Si-HM) or EUV under layer should be around 5nm FTK. In this case, it is too difficult to transfer to SOC or bottom hard mask layer. In order to prevent this critical issue, we propose new functional surface treatment process and primers (FSTP) on the conventional CVD and spin on hard mask. This FSTP is a spin coating material. However it is almost single molecular type ultra-thin primer (~1nm) for all of the CVD and spin on hard mask (SiON, SiN, TiN, SiO2, SiHM, SOG and so on) not to bother fine pitch pattern transfer. In our recent experimental, one of the FSTP has high universality to EUV PR CAR and MOR to achieve high patterning performance in EUVL. Moreover, the other one of the FSTP specially optimized for MOR process showed 20~30% dose reduction on inorganic substrate. Therefore FSTP has big advantage and potential in EUV lithographic process and pattern etch transfer enhancement for next generation High NA EUV process.

As the awareness of climate change and sustainability grows, industries are placing more commitment to reduce their environmental footprint. Semiconductor companies are no exception, and many are now working to reduce their greenhouse gas (GHG) emissions and adopt greener practices as crucial steps towards a more environmentally responsible future. Amongst the top sustainability challenges faced in semiconductor manufacturing, electricity consumption emerges as a critical concern, with lithography tools requiring a substantial amount of energy to operate. As a track vendor, reducing energy consumption and optimizing tool efficiency are ongoing challenges at SCREEN, where hotplate processes rank amongst the most energy-intensive operations, especially during the bake of underlayer materials that require high temperatures to achieve full film densification. This paper shows an innovative energy-efficient process as a viable alternative to conventional spin-on carbon (SOC) and spin-on glass (SOG) thermal crosslinking systems. We deeply explore the feasibility to use an overall-wafer exposure system integrated on SCREEN’s DT-3000 track to harden underlayer materials specifically designed to crosslink via light, without the need of heat. We demonstrate how migration from a hotplate process to a 100% optical curing mechanism can lead to outstanding savings in energy and process time, while keeping the lithographic performance.

A non-PFAS biomass EUV resist is proposed as a sustainable material for reducing PFAS and CO₂ emissions. It was demonstrated that HP 8nm L/S pattern formation with a non-PFAS biomass EUV resist for beyond 2nm node. Furthermore, biomass developer and rinse for non-PFAS biomass EUV resists are proposed to improve biomass content. This proves that the non-PFAS biomass EUV resist can be used in high-NA EUV lithography at 8nm.

It is extremely important to reduce CO₂ in the world and to achieve carbon neutral. Various bio-based green materials using biomass made from plants/woods are proposed for achieving carbon neutral. This paper describes biomass developer solvent made from plants for lithography application. CO₂ is markedly reduced, and it is reported reusing of the biomass developer after development process.

Metal oxide photoresists are recognized as an integral component in the high–numerical aperture future of EUV lithography and the challenging feature sizes required at associated nodes. Many properties of these materials, such as their high EUV absorptivity, etch selectivity, and relatively small molecular size are particularly beneficial for enabling the advancement of lithographic processes. To help ease process development efforts involving these materials, a previously reported rigorous stochastic lithography model has been built using in-depth knowledge of the chemical and material processes that govern the behavior of spin-on metal oxide resists. Experimental data from a series of measurement techniques were used to both define and parametrize the fundamental equations that underlie the lithographic performance of these materials. The resulting parameters were then calibrated to a dataset derived from an extensive series of CD-SEM and open-frame exposures. In this model update, the match between simulated data and experiment has been improved both by more targeted calibration efforts and by the inclusion of more diverse exposure measurements into the calibration dataset. Interrogating the changes necessary to improve performance provides insights into resist behavior and how disparate process steps are interrelated. The updated model is used to simulate a series of exposure conditions outside of the calibration dataset to both validate the model and show its capabilities. Together, the fundamental nature of the model and the insights gained through its calibration provide a powerful tool to drive process optimization for metal oxide materials.

For designing high-resolution integrated circuits, extreme ultraviolet (EUV) lithography using 13.5-nm light is indispensable; however, stochastic issues which can result in pattern roughness and stochastic defects have yet to be resolved. Many of these issues can relate to the low photon density when compared to DUV lithography. To resolve stochastic concerns in chemically amplified (CA) photoresists, it is important to use appropriate photoacid generator (PAG). EUV PAGs are designed to capture secondary electrons that originate from EUV irradiation to the photoresists. Herein, we focused on in silico analysis of C-S bond cleavage of sulfonium cation series, which is a well-known mechanism in production of photogenerated acids. Change in cation types or substituted functional groups directly affect electron affinities of PAG cations, as well as the efficiency of C-S bond cleavage reaction. Finally, the correlation between actual lithographic performance and calculated properties was carried out to understand the factors that influence efficiency of photoacid generation.

Karhunen-Loève expansion (KLE) is a generalization of principal component analysis (PCA) to random fields and random processes, providing optimal basis functions to represent random stochastic variability most accurately, ensuring the minimal mean square approximation error. Application of KLE to EUVL stochastic modeling is proposed and illustrated on examples of stochastic failure probabilities calculation (tip-to-tip pinching probability for metal layers and “via missing” probabilities for the via layers), providing the insight into the mechanisms of stochastic variability in EUVL.

Mechanisms of reactions occurring in chemically amplified resists (CARs) upon exposure to EUV light, and their effects on latent image formation, remain poorly understood. To better control stochastics related to chemical reactivity in CARs, our goal is to develop a model that correctly captures the rates of formation of products that can be experimentally measured in an ESCAP photoresist upon exposure to EUV light. We have previously reported the generation of a chemical reaction network that describes reactions likely to occur upon EUV exposure of a random copolymer of poly(hydroxystyrene) and poly(methylmethacrylate), triphenylsulfonium nonaflate, and triphenylsulfonium cyanobenzoate. Here, we detail the use of this network to create a reaction-diffusion model where photoionization, electron ionization, and electron attachment occur, as well as reactions between ions and species formed from photon- and electron-catalyzed processes. Results from this model can be directly compared to future experimental work conducted on ESCAP photoresists.

Ion exchange resin treatment is an effective way to remove impurities from chemicals including lithography chemicals. Among all, H-type strong acid cation resin (SA-IER) or materials with strong acid functional group show the relatively high metal removal performance due to its strong acidity. However, such strong acidity often causes hydrolysis of ester. For instance, hydrolysis reaction between propylene glycol monomethyl ether acetate (PGMEA) and strong acid functional group produces propylene glycol monomethyl ether (PGME) and acetic acid. On the other hand, H-type chelating resin (C-IER) can remove metal impurities to ppt level without causing hydrolysis. One issue was the Cr removal which was lower than other metals. As a solution, we optimized the mixed ratio of H-type C-IER and H-type SA-IER to increase the Cr removal performance without causing hydrolysis. The optimized volume of SA-IER in the mixture was 20 to 33 %. Another issue was the conditioning of ion exchange resin to remove water content from the resins and replace to target chemicals, particularly the solvents. Our new eco-friendly method for conditioning using MeOH significantly reduced the total amount of solvent needed for conditioning of ion exchange resins.

In this study, we present the development of PFAS-free AZ^® FZero 3DT positive photoresist and AZ^® FZero NX-3015 negative photoresist. These novel photoresists were enabled by the utilization of a newly developed PFAS-free M PAG (photoacid generator). Both AZ^® FZero 3DT and AZ^® FZero NX-3015 photoresists have exhibited comparable lithography performance to their PFAS-containing comparative examples on both Silicon (Si) and Copper (Cu) substrates. Furthermore, the newly developed PFAS-free M PAG has displayed good stability on Cu substrates, outperforming the commercial oxime sulfonate PAG. This stability is particularly crucial for the successful application of photoresists in the fabrication of re-distribution layers (RDL) in advanced semiconductor packaging.

As technical advances continue, the pattern size of semiconductor circuits has shrunk. Defect control becomes tighter due to a decrease in defect size, which affects the image printed on the wafer. It is critical to the photomask, which contained a considerably shrunk circuit and an ultra-high-density pattern. In this paper, we introduce a study of acicular defects in Post-Exposure Bake (PEB) process Airborne Molecular Contamination (AMC). Environment AMC impact masks before and during the PEB process generate a unique defect we call an acicular defect. Based on the experiment results, we will apply different Chemically Amplified Resist (CAR) to different contaminated conditions, which produce varied phenomena including shape and distribution. An appropriate solution to mitigate defects caused by AMC of the PEB process will be proposed.

Extreme Ultraviolet (EUV) lithography poses an ever greater challenge to RLS (resolution, line edge roughness, and sensitivity) than previous photolithography methods as lithographers try to achieve sub-14nm pitch in a single-exposure. Additionally, EUV is particularly susceptible to stochastic imaging defects. Although standard chemically amplified resists (CARs) can be exposed with EUV, these materials struggle to achieve resolution targets at manufacturable doses due to limitations in laser source power and resist sensitivity and contribute to stochastics by nature of their random distribution of components. An innovative approach with Inpria Metal Oxide Resists (MORs) can offer an alternative to overcome both EUV resolution and sensitivity limitations, as well as address stochastic defects. On the other hand, traditional sources of defectivity, such as particles, present another challenge, especially when moving toward high-volume manufacturing. Ultrahigh molecula r weight polyethylene (UPE) membrane filters have been used for metal oxide EUV resist filtration because of their high retention efficiency and excellent photochemical compatibility. However, newly designed UPE filters with innovative membrane morphology are needed to further lower defectivity rates with these new resists. This paper describes efforts to continue to improve metal oxide EUV resist defectivity through filtration optimization. A comparative study of the patterning performance of various Point-of-Use (POU) filters is presented. Several filters utilizing a variety of retention ratings and membrane designs were installed on a TEL Clean Track^TM Lithius Pro^TM Z series. A metal oxide EUV resist was filtered and coated on wafers that were subsequently analyzed for patterning defect performance. This study examines the efficacy of optimized filtration design to reduce defects and provides a recommendation to achieve lower defect density.

Extreme Ultraviolet (EUV) patterning technology was deployed for the mass production of 7nm logic devices in 2018 and recently achieved 5nm. The demand for device scaling has produced more complex processes and expensive multiple-patterning requirements. Broad consensus on the direction of EUV technology has triggered the semiconductor industry to aggressively push new resist material development, particularly designed to overcome stochastic issues, which coincides with the establishment of the single-print capability infrastructure for the high numerical aperture (NA) EUV scanner. Although standard chemically amplified resists (CAR) have been struggling to overcome stochastic issues, they have improved significantly to demonstrate 24nm resolution with single exposure patterning using ASML’s NXE3400B. At the point of use filtration, ultrahigh molecular weight polyethylene (UPE) filters have been widely used to eliminate traditional sources of defectivity, such as particles and aggregates in photoresist materials thanks to their high retention efficiency and excellent photochemical compatibility. However, newly designed UPE filters with innovative membrane morphology are needed to further lower defectivity rates. This paper describes our efforts to optimize filtration and improve photoresist defectivity. A comparative study of the patterning performance of various POU filters is presented. Several filters utilizing a variety of retention ratings and membrane designs were installed on a TEL Clean Track^TM Lithius Pro^TM Z series. An EUV CAR resist was filtered and coated on wafers that were subsequently exposed, etched in hardmask stack, and analyzed for patterning defect performance. This study examines the efficacy of optimized filter design to reduce defects and provides a recommendation to achieve lower defect density.

The pattern size of semiconductor circuits has been shrunk as technical advances continued. It is critical to the photomask which contained a considerably shrunk circuit and ultra-high density pattern for sub–20nm tech devices. Develop process has a great impact on the quality of the photomask manufacturing such as CD uniformity and defect control. In this paper, we discussion two develop optimization cases to improve CDU and to reduce process defects.

Pattern selection for OPC (Optical Proximity Correction) model calibration is crucial for high-quality OPC results and low edge placement error (EPE) error in semiconductor fabrication. Pattern coverage check is also desired with the value to identify potential anomaly before mask tape out for monitoring and repair. This study evaluates pattern diversity based selection and pattern coverage check for Extreme Ultraviolet (EUV) C/H mask layers. Pattern diversity based selection has the advantage of incorporating information related to lithographic contrast and illumination effects, offering a more nuanced representation of patterns in a lithographic context. Using unsupervised machine learning, we analyze the lithographic pattern representations from sample designs and select out pattern representatives for OPC model. The study concludes pattern selection and coverage check can enhance model prediction performance for the OPC applications.

Metal deposition on a substrate using the lift-off process plays a vital role in the semiconductor industry to generate metal interconnects. The metal deposition on the substrate can be carried out using the process of evaporation or sputtering. In the metal lift-off process, the substrate is first patterned with resist followed by metal deposition using either the evaporation or sputtering process and eventually the photoresist is removed using a remover solvent. In both the deposition techniques, a unique undercut profile of the photoresist is desired. For metal deposition using the evaporation process, the photoresist is required to have a ‘re-entrant’ profile. On the other hand, for deposition using the sputtering process, the photoresist is desired to have a ‘T-shaped’ profile typically achieved using a bi-layer process. The AZ^® LNR-003 formulation is a chemically amplified negative tone photoresist developed by EMD Performance Materials Corp. designed to generate a T-shaped profile, suitable for the metal deposition using the sputtering process. The undercut profile can be tailored by modifying the process conditions such as post applied bake temperature, post exposure bake temperature and development conditions. The formulation comprises of a specific combination of photoacid generator, quencher and additive which generates the ‘T-Shaped profile’. The AZ^® LNR-003 photoresist can replace the bi-layer process used at present in the semiconductor industry to generate the ‘T-shaped’ profile with a single layer step.

With the continuous scaling down of device size, the development of photoresist materials with high sensitivity and low pattern roughness has become of greater importance in order to achieve finer pattern structure required for advanced next-generation devices. The major obstacle that delays the material development process is the difficulty in predicting the changes in pattern profile depending on exposure conditions, such as dose, illumination system and reticle type. Moreover, the prediction becomes more difficult for schemes with complex pattern structures, since there can be discrepancy in photo-activity of different resist components according to the variation in the amount of incoming light intensity. Herein, we demonstrate a method to estimate the lithographic performance of a photoresist material by advanced contrast curve analysis. With this method, we were able to identify the key photoresist component leading to discrepancy between the pillar pattern profiles at bock-center and block-edge, and apply to the design of the best performing NTD CAR-type photoresist for fine pillar pattern with improved pattern uniformity. This contrast curve analysis method allows efficient material screening by assessing the lithographic performance of different resist materials without actual pattern evaluation by electron microscopy. We expect that this method will greatly contribute to the acceleration of the material development process for next-generation devices.

The polyethylene (PE) membrane plays a crucial role in the semiconductor industry for bulk photochemical and photoresist filtration, owing to its exceptional particle retention capability and substantial chemical compatibility. Over the past few decades, researchers have made significant advancements in the development of polyethylene membranes with smaller pores in order to mitigate product defectivity. The necessity for filtration, however, has grown in tandem with the progress of the semiconductor manufacturing process. Based on the growing demands, there is a need to explore innovative membranes that possess enhanced particle retention ability and cleanliness levels. In this research, we created a new 1 nm PE filter, exhibiting exceptional filtration capabilities. Therefore, this research aimed to compare the differences between the new 1nm PE filter and the traditional 1nm PE filter, as well as to analyze the factors that contribute to the superior performance of the new 1nm PE filter.

Recent advancements in extreme ultraviolet (EUV) lithography have greatly enhanced the manufacturing of fine semiconductor nodes in high volume production (HVM). With the introduction of high NA (numerical aperture) EUV, further miniaturization is expected, and it is necessary to develop lithography technology to accommodate this. Chemically amplified resist (CAR) is widely used in HVM due to their stability and advantages as metal–free resists, and adapting CAR to the High–NA EUV era has important implications. Achieving high resolution in EUV involves a trade–off between resolution, line width roughness (LWR), and sensitivity. Reducing roughness is especially important because roughness can cause pattern defects. This paper aims to reduce CAR roughness and improve the trade–off. We investigated the reduction of roughness through a post–development treatment applied to EUV–exposed patterns. To examine the influence of this post–development treatment, we performed a power spectral density (PSD) analysis of LWR. Additionally, we compared the cross–sectional shape of resist patterns before and after treatment to understand the reactions occurring within the resist. The results showed that the LWR decreased by 13.1% for 44nm line/space (L/S) pitch and 4.0% for 28nm L/S pitch after the post–development treatment. Of particular interest, the use of additional processing demonstrated the potential to reduce low–frequency roughness, which is normally very challenging. These results show the potential for the application of CAR in next–generation lithography.

We introduce a metal infiltration technique to improve lithographic pattern fidelity. By applying vaporized metal-containing gas, metal was infiltrated into a chemically amplified resist (CAR) to alter the etching resistivity. Interestingly, the altered CAR exhibited both metal and organic properties, exhibiting etch selectivity to spin-on-glass and spin on carbon, respectively. We explored the properties of metal-infiltrated CAR and used them to improve pattern fidelity. For example, hole pattern could be transferred more rectangularly. In addition, we investigated whether hole shrink could be realized by volume expansion.

The drive toward tighter pitch and higher density integrated circuits requires continual advancement in lithography. Advanced photolithography tools use extreme ultraviolet (EUV) light with a wavelength of 13.5nm. The high energy nature of EUV light generates secondary electrons in the photoresist that are responsible for the photochemistry that induces the solubility switch. This distinct mechanism has provided the driving force for the development of new photoresists that are sensitive to EUV and highly reactive toward secondary electrons. Despite the considerable change in acid generation mechanism going from DUV to EUV, chemically amplified photoresists continue to be leading photoresist candidates for new process nodes at low NA EUV (0.33 NA) and their use is expected to extend into early high NA (0.55 NA). Herein the after-developer defects (ADI) and EUV P36 LS trench printing performance of a series of chemically amplified photoresists (CAR) with distinct chemistry developed specifically for EUV lithography are compared. In particular, the relationship of different leaving group chemistries and polymer manufacturing processes on stochastic defectivity is explored as well as the connection to photoresist polymer hydrophobicity and homogeneity. The insights gained from this study guide design strategies for improvement of advanced chemically amplified photoresists for EUV lithography.

Spin-on glass (SOG) underlayers to enhance extreme ultraviolet (EUV) lithography for patterning below 28-nm pitch require an in-depth understanding of the required adhesion forces necessary for good lithography. Here, we proposed a fundamentally new SOG underlayer platform composed of polymer blends that can achieve superior uniformity to improve line fidelity and provide a design path for underlayer materials. The structure and property of elemental composition and surface energy can be controlled easily and precisely by varying the combination of polymer, and consequently understanding and tuning the lithographic performance. The lithographic performance of SOG blends was evaluated using NXE3400 EUV exposure system to print 13-nm and 14-nm HP line-space features and contact hole features with CD of 20-nm. The results show that the polymer blends expand the process window for EUV resist for line-space with printable CD >11 nm and biased LWR to 3.6-nm without impact on dose when compared to conventional copolymers. In the case of CH patterning, CDU and DOF improvements were observed when compared to conventional SOG copolymers. Systematic studies on polymer blends based on functional groups and formulation compositions are in progress to establish a better understanding of enhancement of EUV lithography.

We developed a new concept of organic-inorganic hybrid multi-layer EUV PR with a vertical molecular wire structure. Organic-inorganic hybrid multi-layers are deposited by sequential deposition of organic and inorganic molecules. And each organic and inorganic layer has a specific function. Each inorganic layer can have special functions such as high EUV absorbance, high electron reactivity, and etch resistance, and the components and composition of each layer can be freely changed to achieve high EUV sensitivity and excellent plasma etching resistance. In addition, by introducing organic molecules between inorganic molecules, horizontal cross-linking is limited, making it possible to grow a thin film with a vertical molecular wire structure with a spacing between molecular wires of 1 nm or less. And thereby an exceptionally low LER can be generated.

EUV lithography has already introduced in high volume manufacturing and continuous improvements has allowed to resolve pitch 24nm line and space (L/S), pitch 32nm contact hole and pillar pattern with single exposure at even numerical aperture (NA) 0.33. However, pattern roughness, local critical dimension uniformity (LCDU) and process related defects are still major challenges with decreasing critical dimensions (CD). Pitch downscaling also require the use of thinner photoresist mask to prevent pattern collapse from high aspect ratios. Thinner photoresist mask is challenging for pattern transfer because the resist “etch budget” is becoming too small to prevent pattern break during plasma etch transfer. It is required to investigate a co-optimization of lithography processes, underlayers and etch processes to further EUV patterning extension. In this paper, our latest developed process solutions to extend the limits of EUV patterning will be reported. The advanced performance for metal oxide resists (MOR) will be introduced, with a focus on defect mitigation, dose reduction strategies and CD stability.

In this study, we present a method to enhance the sensitivity of fluorinated EUV resists by leveraging the rapid coupling reaction between electrophilic carbon radicals and electron-rich alkenes. To validate the impact of the vinyl groups, DVS-HNF was synthesized by introducing fluorinated alkyl chains and silyl vinyl functional groups into the model compound. Additionally, TMS-HNF and EDMS-HNF, which do not contain a vinyl moiety, were synthesized for comparison. To evaluate the patterning properties of the three materials, e-beam lithography experiments were conducted, resulting in the formation of negative-tone patterns for all three materials. Comparing sensitivities, DVS-HNF with two vinyl moieties exhibited the most excellent sensitivity, confirming the effective collaboration between fluorinated alkyl radicals and vinyl groups. After performing an EUV lithography experiment on DVS-HNF, it was confirmed that a 30 nm negative-tone pattern was successfully formed with excellent sensitivity. These results substantiate the potential of the single-component molecular resist for high performance EUV lithography.

We report on the relationship between resist make-up, filtration process & CH AEI defectivity for an advanced CAR resist with fast dose. In particular, the effect of a pattern transfer scheme on a resist platform with formulation & filtration variation is examined. Resist design & manufacturing strategies for continuous improvement of EUV CAR lithographic performance will be discussed.

Chemically amplified resists (CAR) enable the transition of extreme ultraviolet (EUV) lithography to high-volume manufacture (HVM). Novel photoresists continue to be designed to meet the simultaneous improvement of resolution, line width roughness, and sensitivity (RLS) trade-off. The absorption of EUV photons in the photoresist film leads to emission of primary electrons to form secondary electrons by inelastic scattering events which in turn leads to the activation of the photoacid generator compound. A unique challenge for the use of CAR in EUV lithography is their poor absorption at 13.5nm wavelength. Understanding the photoresist EUV absorption impact on lithographic performance parameters is critical for photoresist design. In this study, we designed photoresist polymers with tuned EUV absorption coefficients by incorporating EUV absorption group(s) onto different CAR polymers. The effect of the EUV absorption increase on polymer properties as well as on resist lithographic performance will be presented.

In the ever-evolving landscape of semiconductor manufacturing, ensuring impeccable process stability and defect control remains crucial in modern lithography. These elements have driven the maturation of the entire extreme ultraviolet (EUV) lithography ecosystem, which is now geared to meet the upcoming challenges. A critical component of this ecosystem is the lithography track, whose performance capabilities have been evolving rapidly to keep pace with technology roadmap advancements. In this study, we present the capabilities of novel hardware solutions integrated into SCREEN's DT-3000 coat-develop track system when applied to metal oxide resist (MOR) platforms. We demonstrate how hardware development remains a fundamental driver for enhancing not only process stability and defect control but also for optimizing additional critical metrics such as resolution, line width roughness (LWR), defect-free window, and pattern shape. These advancements underscore the continued importance of hardware innovation in the semiconductor manufacturing landscape and its indispensable role in supporting the transition to high-NA EUVL technology, ensuring high-quality and reliable production.

For adopting DSA patterning technology to implementation of upcoming DRAM nodes, a novel, unique, and user-friendly wet etch process was introduced. Our concept performs for good etch selectivity in design which facilitates high resolution patterning, and potentially offers an alternative solution to conventional dry etch techniques especially where CD goes smaller with a higher aspect ratio. This paper will discuss more in detail the concept of wet chemistry and design strategy which were developed for processing PS-b-PMMA (polystyrene-b-polymethyl methacrylate) hole patterns for advanced nodes. Besides, we further open perspectives of our wet etch strategy to new process development which does not require UV cure. Preliminary experiment and successful demonstration on PS-b-PMMA-based hole patterns will also be discussed in this paper.

In the application of extreme ultraviolet (EUV) lithography, stochastic defects are one of the fundamental issues, and the improvements of the sensitivity of resist materials are one of the requirements for the application of EUV lithography process to the future nodes. As reported before, as the absorption of EUV photons depends on the species of element in each material, we have studied introducing the iodine element to lithography materials for the sensitivity issues in EUV lithography process. On this report, the studies of the effect of applying the iodine-containing material to the underlayer of resist film are shown by monitoring the mechanism of the chemically amplified resist system and the evaluation the performance of patterning.

As extreme ultraviolet lithography advances towards patterning smaller features, stochastics and sensitivity are two challenges that polymeric photoresists must overcome. Traditionally, synthetic limitations cause chain-to-chain variations in polymer molecular weight, composition, and sequence which are compounded by material stochastics in resist formulations. Together with poor EUV absorption by polymeric materials, this contributes to unacceptable levels of line-edge roughness and other patterning defects. Polypeptoids are a unique class of bio-inspired polymers that can be synthesized with a perfectly defined sequence, composition, and molecular weight, yielding a uniform material. In this study, we have incorporated metals and halogens into polypeptoid-based chemically amplified resists to investigate the impact of strongly EUV-absorbing elements on the sensitivity of polymeric photoresists. These polypeptoid CARs have been evaluated under DUV and electron-beam lithography.

An effective filter start-up method has been required by semiconductor device manufacturers, mainly in order to reduce waste volume of lithography process chemicals, which become more expensive as lithography technology advances. To quantify filter start-up status, remaining air in the filter was monitored during static-pressure-driven filter start-up using a sub-1 nm rated Pall high density polyethylene (HDPE) membrane filter varying the solvent type. As a result, correlation for the solvent throughput required for filter start-up to the solvent-membrane material affinity defined by Hansen solubility parameter (HSP) was seen. This is similar to Nylon 6,6 membrane filter results in our previous study. There are exceptions such as nBA requires less throughput than dodecane and so does PGME/PGMEA 7/3 mixture than cyclohexanone, while dodecane and cyclohexanone have better affinity to HDPE (=lower HSP distance). These exceptions can be explained by lower viscosity of nBA and PGME/PGMEA 7/3 mixture probably increasing solvent penetration speed into the filter membrane pores. These results show that quicker start-up of HDPE filtration products can be achieved for solvents with higher affinity and lower viscosity.

Augmented reality (AR) and virtual reality (VR) markets have been growing rapidly. To sustain that growth, materials that can push the boundaries on optical performance are necessary. Optical components, such as waveguides, microlenses, and antireflective coatings, are utilized in near eye display (NED) devices. High-performance high- and low-refractive-index (RI) materials that can be successfully integrated into such devices are needed. Enabling these materials for fabrication process compatibility as well as having good reliability, durability, and sustainability is key to the successful manufacture of these devices. Polymeric materials have the advantage of flexibility and ease of processing. Organic platforms containing no metal-based components have been developed with high refractive index (1.6 to 1.8) and high transmission (>99%). These materials can be patterned using lithography and plasma etch, and in some cases, they can also be made photoimageable. Pushing to higher-RI, spin-coat-friendly films containing metal or hybrid systems with refractive index greater than 1.8, and even up to 2.2, have been developed. Fluorine-free ultralow-refractive-index (<1.25) materials that can be applied through spin coating or other deposition processes are also presented. Low-temperature processing of these materials is a key advantage, allowing these materials to be cured at low temperatures and making them suitable for plastic substrates.

Line-edge roughness (LER) in polymer photo-resist technology is a crucial factor limiting spatial resolution. The impact of inhomogeneous monomer sequences on LER remains unclear despite efforts to narrow sequence distribution during polymerization. To unravel this sequence-LER correlation, a polymer sequencer using pyrolysis mass spectrometry is introduced. It identifies and quantifies short sequence populations termed "codons," even amidst random copolymer fragmentation. Codon complexity increases with length and monomer components. A data-driven approach accommodates growing complexities, enabling quantification of codon compositions for binary and ternary triads with small datasets. This sequencer sheds light on the sequence-LER relationship, offering valuable insights into copolymer properties.

The purity of fluids exposed to a wafer is critical as the node sizes are approaching low single digit nanometers. The potential impurities could be solid or semi-solid particles, soluble metal cations, anions, organic species, or gases. All these need to be removed for optimum yield and minimal defects. The technical challenge associated with reducing the node sizes also relates to membranes production as membranes with low single digit pore sizes are needed to remove nanometer impurities. The interest in nylon membrane is twofold as it can mechanically remove fine particles as well as by its adsorptive capabilities. In this study, nylon membranes with pore sizes of 2, 5, 10, and 20nm were characterized for microstructure, flow rate versus pressure drop, bubble point, and metal extractables in PGMEA.

The electrical microstructures on chips become ever more sensitive to microscopic contaminants as semiconductor technology nodes evolve to require more processing capacity and power efficiency. Strict control of possible defect sources is required to protect sensitive chip patterns. One such source is the lithography material filter itself. In advanced processes such as EUV and ArF, filter cleanliness has become increasingly vital to achieving superior and stable on-wafer defect performance. Filter extractables can result in cone defects, scum defects and other undesirable yield-impacting issues on wafers. In addition to the adoption of a highly retentive media, this next-generation nylon filter delivers superior defect performance via enhanced raw material cleanliness along with advancements in filter cleaning technology. Cleanliness evaluations in this study demonstrate that the newly developed ultra clean nylon filter has lower levels of metallic and organic extractables in organic and acidic solvents. Furthermore, the new filter’s high stability and low pH extractables suggest it can be adopted to certain acidic photochemicals such as used in SiARC and BARC applications. Lastly, field photochemical testing shows a reduction in on-wafer defects for this new technology.

Per- and polyfluoroalkyl substances (PFAS) have been identified by various regulatory bodies as substances of concern. In line with the objective of safer and sustainable by design, a comprehensive program has been initiated to address these concerns. Part of this program includes the development of non -fluorinated photoacid generators (PAGs) without introducing new chemicals with unintended consequences. Using computational chemistry and synthetic organic chemistry , several scaffolds amenable to PAG library design have been realized. These novel PAGs offer facile tunability and advantages in many critical design parameters such as pKa, diffusion, absorption, shelf-life stability, and scalability. These early generation non-fluorinated PAGs show competitive and similar lithographic performance compared to fluorinated PAGs in i-line, krypton fluoride (KrF) laser, argon fluoride (ArF) laser and extreme ultraviolet (EUV) lithography.

The semiconductor industry is currently transitioning to advanced extreme-ultraviolet lithography (EUVL) to address the challenges facing the use of photolithography in microprocessor and memory chip integration. This shift has sparked a surge in novel inorganic EUV photoresist research. However, several technical issues, such as insufficient EUV sensitivity, poor understanding of the photochemistry, and poor stability, have emerged. Here, we synthesized [(BuSn)₁₂O₁₄(OH)₆](CH₃C₆H₄SO₃)₂ (TinTos) as a standard EUV photoresist. Chemical analysis (PXRD, NMR) was performed to confirm that the synthesized TinTos was well reproduced. As a result of EUV exposure, TinTos showed low sensitivity compared to the dose required in industry (<50 mJ/cm²). However, no enhancement in the DUV sensitivity was observed for TinTos after PEB. Consequently, we anticipate less time-dependent behavior of TinTos.

Lifetime extension of metal removal application utilizing Nylon 6,6 membrane was investigated with point of use (POU) filters. In this study, new samples which applied Nylon 6,6 membrane with different membrane properties including thickness, area and volume as well as ref. sample with standard membrane were prepared to investigate parameters which are expected to affect the metal removal capacity with breakthrough testing to analyze of metal removal effectiveness. As a result, it was found that the sample with thicker membrane leading to a larger membrane volume tended to show increased metal removal performance. Best correlation was seen with membrane volume (thickness × area) for metal removal performance. Data of flow dP(differential pressure), liquid particle count and initial cleanliness using metal extractions were also collected as fundamental filter performance. Lastly, we confirmed that these new samples showed lower flow dP and comparable cleanliness performance to ref. sample. Based on this study, we successfully developed a new Nylon filter which extends the metal removal lifetime while keeping comparable cleanliness and greater flow dP (differential pressure) performance using the same capsule format. These findings will be very useful in the development of next-generation filtration products, ultimately contributing toward reduced defectivity and increased yield within next-generation lithography processes.

In the realization of further miniaturization at scales of 10nm and below in semiconductor devices, it is essential to get the new resist design such as hybrid inorganic-organic resist materials for ionizing radiation to clarify the effect of metal resist structure on resist performances. In this study, some hybrid inorganic-organic resist materials known as metal-oxo clusters were synthesized and their lithographic characteristics were investigated to clarify the difference in sensitivity and resolution among Ti-based, Zr-based and Hf-based oxo clusters by using EUV and EB exposure. Our results indicated that the sensitivity in Hf-based oxo clusters was higher than those of Ti-based and Zr-based oxo clusters in both EB and EUV exposure. Also, we clarified that it is very important for the new resist design such as hybrid inorganic-organic resist to increase photo-absorption cross section and density of elements. In particular, the size and homogeneity of particle and film quality is very important for resist performance of hybrid inorganic-organic resist materials. In addition, it is clarified that etch durability increased by annealing metal oxo clusters.

Underlayer materials account for the majority of electricity consumption in the lithography process because all tracks need to maintain a high temperature not only during the process time but also throughout the entire operational period. In this study, we propose a novel method that deviates from the conventional approach of utilizing thermoplastic materials as the underlayers for crosslinking, instead advocating for the use of light source for the crosslinking process, which potentially leads to reduced electricity consumption. Furthermore, some studies have shown that light-curable materials exhibit a higher degree of crosslinking compared to thermally cured materials, which implies that better crosslinking may provide better lithography performance. We evaluated light-curable materials based on the thermoplastic underlayers used in conventional EUV lithography.