SungEun Hong

Implementation of surface energy modification in graphoepitaxy directed self-assembly for hole multiplication

A graphoepitaxy directed self-assembly process using cylindrical phase block copolymers is regarded as a promising approach for patterning irregularly distributed contact holes in future integrated circuits. However, control over cylinder profile and open hole rate, among others, needs to be proven before this technique can be implemented in device fabrication. Computational simulation studies predict that selective control over the surface energy of the template bottom and sidewall is crucial for achieving perpendicular cylinders in an adequate range of template dimensions and block copolymer fill levels. This work offers an experimental investigation of the influence of the surface energy on the morphology of the assembly inside the template. For this study, a dedicated surface energy modification is implemented in our process flow. Selective control over the surface energy of the template bottom and sidewall is achieved by using random copolymer brushes. The optimization of surface energy prior to the ...

Directed self-assembly of topcoat-free, integration-friendly high- x block copolymers

To extend scaling beyond poly(styrene-b-methyl methacrylate) (PS-b-PMMA) for directed self-assembly (DSA), high quality organic high-x block copolymers (HC series) were developed and applied to implementation of sub-10 nm L/S DSA. Lamellae-forming block copolymers (BCPs) of the HC series showed the ability to form vertically oriented polymer domains conveniently with the in-house PS-r-PMMA underlayers (AZEMBLY EXP NLD series) without the use of an additional topcoat. The orientation control was achieved with low bake temperatures (≤200 °C) and short bake times (≤5 min). Also, these process-friendly materials are compatible with existing 193i-based graphoepitaxy and chemoepitaxy DSA schemes. In addition, it is notable that 8.5 nm organic lamellae domains were amenable to pattern development by simple dry etch techniques. These successful demonstrations of high-x L/S DSA on 193i-defined guiding patterns and pattern development can offer a feasible route to access sub-10 nm node patterning technology.

Influence of template fill in graphoepitaxy DSA

Directed self-assembly (DSA) of block copolymers (BCP) is considered a promising patterning approach for the 7 nm node and beyond. Specifically, a grapho-epitaxy process using a cylindrical phase BCP may offer an efficient solution for patterning randomly distributed contact holes with sub-resolution pitches, such as found in via and cut mask levels. In any grapho-epitaxy process, the pattern density impacts the template fill (local BCP thickness inside the template) and may cause defects due to respectively over- or underfilling of the template. In order to tackle this issue thoroughly, the parameters that determine template fill and the influence of template fill on the resulting pattern should be investigated. In this work, using three process flow variations (with different template surface energy), template fill is experimentally characterized as a function of pattern density and film thickness. The impact of these parameters on template fill is highly dependent on the process flow, and thus pre-pattern surface energy. Template fill has a considerable effect on the pattern transfer of the DSA contact holes into the underlying layer. Higher fill levels give rise to smaller contact holes and worse critical dimension uniformity. These results are important towards DSA-aware design and show that fill is a crucial parameter in grapho-epitaxy DSA.

Directed self-assembly materials for high resolution beyond PS- b -PMMA

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.

Comparison of thermal flow and chemical shrink processes for 193 nm contact hole patterning

This paper compares thermal shrink properties of contact holes and chemical shrink performance for 193 nm lithography. Pitch dependence, shrink properties, contact hole circularity, sidewall roughness, and process window are also discussed. Thermal flow process exhibited more pitch dependence than chemical shrink process. Thermal shrink rate increased substantially at higher bake temperatures. Contact holes in defocused area shrunk non-evenly and DOF deteriorated upon heating. In chemical shrink process, shrink rate was hardly influenced by mixing bake temperature, contact holes from center focus to defocus area shrunk evenly preserving effective DOF and MEF became smaller at smaller CD. Chemical shrink has clear advantages over thermal flow process and sub-70 nm contact holes were obtained with iso-dense overlap DOF 0.25 μm by optimizing resist formulations and process conditions. Application of shrink processes will pave the way for the next generation LSI production.