Impact of materials selection on graphoepitaxial directed self-assembly for line-space patterning

Abstract

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-" 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  parameter of the block copolymer should be optimized to balance LWR, kinetics of assembly, and process window. Glass transition temperature (T g ) of the blocks showed little impact on performance. Overall, parameters of both BCP and brush must be simultaneously optimized to achieve high quality DSA.

Thickness-dependence of block copolymer coarsening kinetics

“…56,66 The strength of interfacial interactions can also influence ordering kinetics. Strong substrate interactions will pin material at interfaces and slow kinetics, 67 while neutralized 68 or even antagonistic 69 interactions will 'lubricate' the BCP-substrate interface, and increase ordering rates. Undoubtedly, substrate interactions are playing a role in setting the overall scale of kinetics measured in our experiments.…”

Rapid ordering of block copolymer thin films

“…It has been shown that DSA patterns can achieve density multiplication with respect to the guiding pattern [178][179][180][181][182], and that templates can enforce complex local patterns [183,184] using minimal design rules [180,185]. Progressively more complex integration of BCPs into realistic industrial microelectronic workflows has been demonstrated [39,183,[186][187][188][189][190][191]. BCPs may thus play a role in future electronics and memory devices (resistive [192,193], phasechange [194,195], or magnetic bit-patterned media [137,196,197]).…”

In Situ Grazing-Incidence SAXS Investigation of Thermal-Induced Self-Assembly Process of PS-b-PMMA Films Deposited on Surface-Modified Substrate

“…For decades, directed self-assembly of block copolymers (BCPs) has attracted increasing attention from researchers because of its ability to form repetitive features at the nanoscale − and thus has exhibited great potential in many applications such as lithography, , water purification, , and photonic crystals. , The application wherein it has the greatest potential is in the field of microelectronics, specifically, in the “bottom-up” method based on self-assembly of BCPs, which has been recognized as a promising strategy for expanding Moore’s law. , As a classic block copolymer, polystyrene- block -poly­(methyl methacrylate) (PS- b -PMMA) is of concern to scientists; for example, the preferential interaction of PS or PMMA with substrate usually leads to the formation of parallel-oriented lamellar or cylindrical domains. However, the parallel-oriented structure is usually not conducive to practical application. − To achieve nanostructures of specific orientations via PS- b -PMMA self-assembly, several strategies, such as the application of an electric field, , surface patterning, , solvent vapor annealing, , and the application of a modified layer, − have been developed. Among these, the most effective method currently in use is the application of a modified layer to mask the preferential affinity between the block molecule and the substrate, to enable the production of vertical nanodomains.…”

“…Quach et al. systematically varied the BCP–substrate interaction parameter and observed that a large incompatibility between the BCP matrix and substrate brush (i.e., large matrix brush) improved the order of the nanodomains. ,, These results suggest that the kinetics of the self-assembly of BCPs on a surface modified layer is the key to realizing morphology control and obtaining a better-ordered structure.…”

“…25 Compared with inorganic modified layers, organic modified layers are more widely applied because of the relatively good diffusion ability between block copolymer molecules and the modified layer. 22,26,27 In addition, spin-cast BCP films are frequently in kinetically trapped disordered configurations and require oven annealing to induce mobility and allow the system to evolve into an ordered state. The block copolymer films are heated over the glass transition temperature T g .…”