Efforts to extend 193 nm lithography have introduced multiple patterning solutions to print a single level layer. Due to this increased complexity, defectivity on each layer is becoming very critical. Micro and multiple line bridges are one of the primary challenges in photolithography contributing to this complexity. These defects originate from several root causes and are difficult to eliminate. Point-of-use filtration plays a significant role on the mitigation of such defects. The impact of filtration rate and pressure was previously documented. In this research, we demonstrate that the combination of membrane and pore size selection, photoresist optimization, and hardware optimization can impact micro and multiple bridge mitigation in a 45 nm line/space pattern created through immersion lithography.
Extreme ultraviolet (EUV) lithography is a candidate for the manufacturing of semiconductor devices at the 22 nm half pitch node and below. EUV lithography requires high performance resist with limited outgassing property. The key challenge for EUV resist is the simultaneous requirement of ultrahigh resolution (R), low line edge roughness (L) and high sensitivity (S) for lines and spaces (LS) features. To achieve high resist sensitivity EUV resist absorbance should be increased. Resin containing fluorine atom is one of the most attractive methods to improve absorbance level of EUV resist because the fluorine atom absorbs EUV light strongly. However, resist hydrophobicity (or high contact angle) also increase due to presence of fluorine atoms in the resist polymer. It is difficult to rinse high CA resist during development process so the resist containing polymer with fluorine atom may produce additional defects. In this paper, we will report the relationship between line edge roughness and acid diffusion length. We will also show the method to diminish defects caused by high contact angle (CA) resist. We achieved good resolution and LER improvement by controlling acid diffusion length. Moreover, we found the relationship of the number of defects and the structure of the monomers containing fluorine units.
In a period where industry strongly struggles to find a cost effective alternative solution to the 193nm double patterning
strategy, resist manufacturers actively started to design new resist platforms for the future lithography candidates such as
EUV or multi-beam. Chemically amplified resists proved their efficiency until now to reach resolution requirements and
simultaneously keeping sensitivity target. Below 20nm, edge roughness starts to play an important role on patterning
quality and critical dimension control. Simultaneously non CAR resist are showing attracting resolution progress with
reasonable sensitivity levels. In the frame of the multi-beam program IMAGINE, performances of advanced resist
platforms have been evaluated at various accelerating voltage: 5kV on the MAPPER multi-beam platform and at 100kV
on a VISTEC Gaussian tool. This paper reports on the comparison results obtained on those two types of chemistry
schemes in terms of resolution, sensitivity and roughness.
As Extreme Ultra Violet technology (EUV) is being introduced, multilayer hard mask patterning becomes a key option
in order to transfer the lithographic patterns into the circuit stack. In particular, spin-on multilayers can play a decisive
role on the process roadmap as a more cost-effective solution than Chemical Vapour Deposition options. The integration
of spin-on hard masks in EUV technology nevertheless requires these products to be EUV-outgassing friendly. In
addition to this, the spin-on solutions must withstand the demanding photoresist and circuit stack aspect ratios during
patterning. This paper presents the EUV process development for contacted metal lines with 30nm half-pitch dimensions
in a dual damascene application. The performance of an all-spin-on multilayer system composed of an EUVphotosensitive
layer, an organic underlayer, a silicon-rich middle layer and a carbon-rich bottom layer is demonstrated.
Firstly, outgassing of the various polymer layers in vacuum is a critical parameter to control since it can directly impact
the EUV-tool-optics lifetime. The qualification, selection and process optimisation of different materials for use in the
ASML NXE:3100 EUV scanner are shown by interpreting Residual Gas Analysis data. The outgassed species for
different types of layers are compared. In this study, the shielding effect of the top layers on the outgassing of the layers
underneath is quantified. The influence of the layer composition is also discussed.
Secondly, the lithographic performance of the 30nm half-pitch process on the NXE:3100 is characterized with process
windows and profile control using the IMEC process-of-reference. The CD uniformity results within wafer and across
wafer-batches are used to demonstrate the process maturity.
Finally, considering the patternability of the EUV process, we demonstrate the ability of the all-spin-on multilayer
system to planarize over the challenging dual damascene topography. To conclude on the potential of this scheme, we
describe the etched dual damascene patterns into a dielectric stack which is representative for the 30nm half pitch
While immersion lithography has been rapidly implemented in manufacturing environments around the world, a few
defect challenges still remain. Bubble and watermark defects are well understood and have been addressed by
equipment manufacturers. However, a few defects still bewilder the lithography community, including residues and
microbridging. These defects are difficult to completely eliminate as they may have many root causes. However,
through effective point-of-use filtration, they can be greatly reduced.
Point-of-use filtration has traditionally focused on selecting a filter membrane at a specific pore size that is compatible
with the resist chemistry being utilized in the process. The research hereby discussed indicates that in addition to these
important point-of-use filter choices, careful filtration parameter setup can improve defectivity results and impact the coating process.
In 2009 a new European initiative on Double Patterning and Double Exposure lithography process development was
started in the framework of the ENIAC Joint Undertaking. The project, named LENS (Lithography Enhancement
Towards Nano Scale), involves twelve companies from five different European Countries (Italy, Netherlands, France,
Belgium Spain) and includes: IC makers (Numonyx and STMicroelectronics), a group of equipment and materials
companies (ASML, Lam Research srl, JSR, FEI), a mask maker (Dai Nippon Photomask Europe), an EDA company
(Mentor Graphics) and four research and development institutes (CEA-Leti, IMEC, Centro Nacional de
The LENS project aims to develop and integrate the overall infrastructure required to reach patterning resolutions
required by 32nm and 22nm technology nodes through the double patterning and pitch doubling technologies on existing
conventional immersion exposure tools, with the purpose to allow the timely development of 32nm and 22nm
technology nodes for memories and logic devices, providing a safe alternative to EUV, Higher Refraction Index Fluids
Immersion Lithography and maskless lithography, which appear to be still far from maturity.
The project will cover the whole lithography supply chain including design, masks, materials, exposure tools, process
integration, metrology and its final objective is the demonstration of 22nm node patterning on available 1.35 NA
immersion tools on high complexity mask set.