Directed self-assembly (DSA) of block copolymers (BCPs) is a promising technology for advanced patterning at future technology nodes, but significant hurdles remain for commercial implementation. While chemoepitaxy processes employing poly(styrene-block-methyl methacrylate) (PS-PMMA) are most widely studied for DSA line/space patterning, graphoepitaxy processes using more strongly segregated “high-X;” block copolymers have recently shown a lot of promise, with lower defectivity and line-width roughness (LWR) than comparative chemoepitaxy processes. This paper reports on some of the design considerations for optimizing line/space patterning with these materials. We have found that brush and block copolymer selection are critical to achieve high quality DSA. For example, brush thickness must be optimized to achieve matching space critical dimensions, and brush surface energy impacts kinetics of assembly. The X parameter of the block copolymer should be optimized to balance LWR, kinetics of assembly, and process window. Glass transition temperature (Tg) of the blocks showed little impact on performance. Overall, parameters of both BCP and brush must be simultaneously optimized to achieve high quality DSA.
Block copolymer directed self-assembly (BCP-DSA) may provide a less costly method of forming sub-38nm pitch line-space patterns relative to proven HVM methods, but DSA needs to provide equivalent or improved defect density and pattern quality to warrant consideration for displacing current HVM methods. This paper evaluates the process constraints of three DSA flows and compares the pattern quality after pattern transfer for each flow at its optimal process conditions to the same pattern created by a proven HVM process flow.
Directed Self-Assembly (DSA) of block copolymers is a candidate advanced patterning technology at future technology
nodes. Although DSA promises resolution and cost benefits, a number of constraints and challenges remain for its
implementation. Poly(styrene-block-methyl methacrylate) (PS-b-PMMA) has been widely studied in DSA and applied in
various applications to demonstrate the potential of DSA to extend optical lithography, including line space and contact
hole patterning and uniformity repair,. However, the relatively weak segregation strength of PS-b-PMMA limits its
capability to pattern sub-10 nm features. This paper presents the use of strongly segregated high X block copolymers to
enable sub-10 nm patterning. Chemoepitaxy DSA with high X lamellar block copolymers is demonstrated with two
different strategies based on thermal annealing process and no top coat. These technologies hold promise to enable the
implementation of DSA at future technology nodes.
In this presentation, we describe multi-scale modeling method combining PROLITH lithography simulation with Self-Consistent Field Theory (SCFT) computation of the block copolymer Directed Self-Assembly (DSA). Within this method, we utilize PROLITH to predict the shape of a lithographic feature as function of process conditions. The results of that calculation are then used as input into SCFT simulation to predict the distribution of the matrix and etchable blocks of the DSA polymers (such as PS-b-PDMS or PS-b- PMMA) inside that feature. This method is applied to simple cases (e.g., rectangular trench and cylindrical contact hole), and the self-assembly of various polymers is investigated as a function of their compositions. The new tool could therefore be applied to rapidly design and screen lithographic process conditions together with polymers used to shrink or rectify the features within the DSA technology.
Shih-wei Chang, Jessica Evans, Shouren Ge, Valeriy Ginzburg, John Kramer, Brian Landes, Christopher Lee, Greg Meyers, Daniel Murray, Jong Park, Rahul Sharma, Peter Trefonas, Jeffrey Weinhold, Jieqian Zhang, Phillip Hustad
Directed self-assembly (DSA) of block copolymers (BCPs) is a promising technology for advanced patterning at future
technology nodes, but significant hurdles remain for commercial implementation. The most widely studied material for
DSA is poly(styrene-block-methyl methacrylate) (PS-PMMA), but the relatively weak segregation strength of PSPMMA
results in some limitations. This paper reports on these limitations for PS-PMMA and highlights a path to
success through use of more strongly segregated “high-χ” block copolymers. In general, stronger segregation is
predicted to lower defectivity at equilibrium, but unfortunately, kinetics of self assembly also becomes much slower as
segregation strength increases. Recognizing diffusion is much faster for cylinder morphologies than lamellar ones, we
have investigated new cylinder-forming BCPs that enable defect elimination with thermal annealing processes. In
addition, a formulation strategy is presented that further improves the kinetics of the assembly process, enabling
tremendous improvements in defectivity over simple BCP systems. Excitingly, successful chemoepitaxy DSA with a
high-χ lamellar BCP is also demonstrated using a thermal annealing process and no top coat. These technologies hold
promise to enable DSA with thermal annealing processing across pitches from 40 - 16 nm.
Directed self-assembly (DSA) of block copolymers (BCPs) is a promising technology for advanced patterning at future
technology nodes, but significant hurdles remain for commercial implementation. The most widely studied material for
DSA is poly(styrene-block-methyl methacrylate) (PS-PMMA), but this material has a relatively weak segregation
strength that has limited its utility to patterns above 24 nm pitch. This paper reports on some of Dow's efforts to develop
new materials capable of extending DSA to smaller pitch by development of new BCP copolymer materials with
stronger segregation strength. Some preliminary efforts are reported on new substrate treatments that stabilize
perpendicular orientations in a high-χ block copolymer that also incorporate an etch-resistant block to facilitate
patterning at small dimensions. In addition, development of new block copolymer materials that have a χ-parameter that
is large enough to drive defect reduction and but not so high that it precludes thermal annealing are also presented. DSA
of these new materials is demonstrated using thermal annealing processes at pitch ranging from 40 to 16 nm, and etch
capability is also demonstrated on a material with 18 nm pitch. These technologies hold promise for the extension of
DSA to sub 24 nm pitch.
A simple theoretical model is proposed for describing thermodynamic properties of chiral- racemic mixtures. It is shown that in the case of chiral-racemic mixtures, spontaneous polarization tends to be linear and Smectic C--Smectic A transition temperature--quadratic function of the enantiometric excess, which is confirmed by our experimental data.
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