Directed self-assembly (DSA) of block copolymer (BCP) thin films has been extensively researched as an alternative lithographic technology to enhance the resolution beyond the limitation of current lithography techniques. One of the most critical factors need to be addressed for DSA process to be accepted at high volume manufacturing (HVM) is defect density of DSA pattern. The defects of thermodynamically driven DSA process, such as the dislocation defects in LiNe flow, are known as kinetically trapped metastable structures. Therefore, a key to eliminate those defects is to find out the effective kinetic pathway of assembly that enables BCP to reach to defect-free structure more easily. In addition to defect annihilation, easy pathway will also allow faster assembly, consequently reducing the cost of ownership of DSA process. The obvious approach for faster assembly in DSA process is to increase annealing temperature. In this study, we address the impact of annealing temperature on DSA process. First, increasing annealing temperature makes the free surface of a PS-b-PMMA film more PMMA preferential. Because of altered boundary condition at the top surface, more careful optimization of backfilling brush was required to maintain preferred orientation of BCP films. Second, the dimension of BCP is also affected by annealing temperature. Temperature dependency of BCP dimension was quantitatively investigated by CD-SEM and DSA-APPS Offline CD Measurement Software (Figure 1a). Based on the measured values, the dimension of chemical pattern is accordingly modified to achieve aligned DSA pattern (Figure 1b). We anticipate our finding from this study can be generally applied for other BCP systems.
 Ruiz, Ricardo, Huiman Kang, François A. Detcheverry, Elizabeth Dobisz, Dan S. Kercher, Thomas R. Albrecht, Juan J. de Pablo, and Paul F. Nealey. "Density multiplication and improved lithography by directed block copolymer assembly." Science 321, no. 5891 (2008): 936-939.
 Gronheid, Roel, Paulina Rincon Delgadillo, Hari Pathangi, Dieter Van den Heuvel, Doni Parnell, Boon Teik Chan, Yu-Tsung Lee et al. "Defect reduction and defect stability in IMEC's 14nm half-pitch chemo-epitaxy DSA flow." In SPIE Advanced Lithography, pp. 904905-904905. International Society for Optics and Photonics, 2014.
 Hur, Su-Mi, Vikram Thapar, Abelardo Ramírez-Hernández, Gurdaman Khaira, Tamar Segal-Peretz, Paulina A. Rincon-Delgadillo, Weihua Li, Marcus Müller, Paul F. Nealey, and Juan J. de Pablo. "Molecular pathways for defect annihilation in directed self-assembly." Proceedings of the National Academy of Sciences 112, no. 46 (2015): 14144-14149.
To extend directed self-assembly (DSA) of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) for higher resolution, placement accuracy and potentially improved pattern line edge roughness (LER), we have developed a next-generation material platform of organic high-χ block copolymers (“HC series”, AZEMBLYTM EXP PME-3000 series). The new material platform has a built-in orientation control mechanism which enables block copolymer domains to vertically selforient without topcoat/additive or delicate solvent vapor annealing. Furthermore, sub-10 nm lines and spaces (L/S) patterning by two major chemoepitaxy DSA, LiNe and SMARTTM processes, was successfully implemented on 12” wafer substrates by using the PME-3000 lamellar series. The results revealed that the new material platform is compatible with the existing PS-b-PMMA-based chemical prepatterns and standard protocols. We also introduced the built-in orientation control strategy to the conventional PS-b-PMMA system, producing a new generation of PS-b-PMMA materials with facile orientation control. The modified PS-b-PMMA (m-PS-b-PMMA) performed LiNe flow DSA yielding a comparable CD process window with improved LER/LWR/SWR after the L/S patterns were transferred into a Si substrate.
This manuscript shows the relationship between defectivity of a typical chemo-epitaxy sequence and the DSA-specific materials, namely the mat, the brush and the block co-polymer. We demonstrate that the density of assembly defects in a line-space DSA flow, namely the dislocations and 1-period bridges have a direct correlation to certain parameters in the synthesis sequence of these materials. The primary focus of this manuscript is on identifying, controlling and reproducing the defects-critical parameters in the block co-polymer synthesis process for a stable and low defect performance of DSA flows.
Shot noise is a significant issue in EUV lithography, especially in printing small area features like contact holes. This
brings about LCDU (Local CD Uniformity) issue and LCDU-sensitivity tradeoff. This paper describes efforts to alleviate
this issue through a novel EUV Underlayer (UL) chemistry design approach. The novel component “buffer” was
introduced into EUV UL formulations to balance back exposure energy from UL to the resist at different incident
positions. Measured back exposure dose from UL shows much lower variation (6σ/mean) compared with shot noise of
resist absorbed dose. Thus summed energy variation will be suppressed when counting back exposure effect of UL,
namely shot noise is reduced. Through reported shot noise model, our calculation suggests 30% sensitivity improvement
and 13.4% shot noise suppression can be expected. Actual lithographic evaluations demonstrated simultaneous LCDU
and sensitivity improvement. The feasibility of 30% sensitivity improvement by Metal hard mask (MHM) material was
tested. The combination of buffer functionalized UL and MHM was modeled.
Photoresists play a key role in enabling the patterning process, and the development of their chemistry has contributed significantly to the industry’s ability to continue shrinking device dimensions. However, with the increasing complexity of patterning ever smaller features, photoresist performance needs to be supported by a large number of materials, such as antireflective coatings and anti-collapse rinses. Bottom anti-reflective coatings are widely used to control reflectivity-driven pattern fidelity in i-line and DUV exposures. While no such reflectivity control is required at EUV wavelengths, it has been demonstrated that use of an EUV underlayer (EBL) coating with high EUV photon absorption (EPA) unit can improve resist performance such as sensitivity and resist-substrate poisoning, thereby improving resolution and process window. EBL can also help to reduce the effect of out-of-band (OoB) irradiation. Traditionally, final photoresist image cleaning after the develop step has been performed using de-ionized water, generally known as a “rinse step”. More recently pattern collapse has developed to a major failure mode in high resolution lithography attributed to strong capillary forces induced by water resulting in pattern bending (‘pattern sticking’) or adhesion failure. With decreasing feature geometries (DPT immersion lithography, EUV) the benefit of rinse solutions to prevent pattern collapse has increased. In addition such rinse solutions can in some cases improve defects and LWR. In this paper we describe the advantages of AZ® EBL series of EUV underlayer materials and EUV FIRM® EXTREME™ rinse solutions when applied individually and in combinations. It is demonstrated that the use of underlayer materials can help improve LWR through improvement of resist profiles. Use of FIRM® EXTREME™ rinse is shown to provide significant improvement in collapse margin and total defect counts.
A phase segregating polymer blend comprising a SOD precursor polysilazane and an organic polymer PSαMS
[poly(styrene-co-α-methyl styrene)] was studied. By utilizing similar approaches employed in DSA (directed
self-assembly) such as patterned substrates, surface chemical modification etc and their combination, we achieved 2xnm
spacer and airgap-like structure. Vertical phase separation and cylinder microdomains in the film of this blend can be
straightforwardly observed by cross-section SEM (Scanning Electron Microscope) respectively. The airgap-like structure
derived from cylinder microdomains was directly obtained on ArF resist pattern. Spacer derived from vertical phase
separation was obtained on pretreated ArF resist pattern.
Conventional trilayer schemes alleviate the decreasing photoresist budgets as well as satisfy the antireflection issues
associated with high NA imaging. However, a number of challenges still exist with standard trilayer processing, most
notable among which is the lack of broad resist compatibility and trade-offs associated with improving Si content, such
as stability and lithography performance. One way to circumvent these issues is to use a silicon hard mask coated over a
photoresist image of reverse tone to the desired pattern. Feasibility of this image reversal trilayer process was
demonstrated by patterning of trenches and contact holes in a carbon hard mask from line and pillar photoresist images,
respectively. This paper describes the lithography, pattern transfer process and materials developed for the image
reversal trilayer processing.