Directed self-assembly of PS-b-PMMA block copolymer using HSQ lines for translational alignment

Abstract

Block copolymers (BCPs) are seen as a possible cost effective complementary technique to traditional lithography currently used in the semiconductor industry. This unconventional approach has received increased attention in recent years as a process capable of facilitating the ever decreasing device size demanded. Control over microdomain orientation and enhancing long range order are key aspects for the utility of BCPs for future lithographic purposes. This paper provides an efficient route for the fabrication of highly ordered nanostructures suitable for such application. We investigate the significant effect of surface treatment regarding the self-assembly process of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) by employing an ethylene glycol layer, producing well defined perpendicular P4VP cylinders with long range order over large surface areas. Nanopores are generated through surface reconstruction using a preferential solvent, which allows for the incorporation of an inorganic moiety.Treatment of this pattern with UV/Ozone leads to formation of well-ordered iron oxide nanodots with a pitch of $26 nm. Furthermore, high aspect ratio silicon nanopillars result following pattern transfer (using Ar/O 2 ).

Self-assembling morphologies of symmetrical PS-b-PMMA in different sized confining grooves

“…Graphoepitaxy, in contrast, uses topographic features to direct the BCP from sidewalls with neutral substrates. 30,31 This has the benets of a simple process, exibility in pattern placement and a potentially high degree of frequency multiplication.…”

“…Differently sized hydrogen silsesquioxane (HSQ) grooves were prepared on a neutralized substrate by electron beam lithography. HSQ has been shown to be a suitable directing material in DSA 31,39 because it can transform into silica at high temperatures. Silica is a very common material in semiconductors and can be easily removed by a solution of HF.…”

Grain-Boundary-Induced Alignment of Block Copolymer Thin Films

“…The approach of directing the self-assembly of block copolymers by means of topographical patterns is referred to as graphoepitaxy. This principle has been successfully employed 2 of 19 by a number of groups, as reported in different works in the last years [9][10][11][12][13][14]. Very low defect densities can be obtained when the width of the confining trench is exactly or close to an integer multiple of the natural pitch of the block copolymer [15][16][17].…”

Self-assembly morphology of block copolymers in sub-10 nm topographical guiding patterns

“…The most frequently used strategies to direct the self-assembly of block copolymers are the fabrication of chemical patterns, referred to as chemoepitaxy, 2,[14][15][16][17] and the fabrication of topographical patterns, referred to as graphoepitaxy. 5,[18][19][20][21] The fabrication of chemical guiding patterns requires patterning techniques with excellent resolution because the chemically modified areas need to be in the size range of the block copolymer domains. 15,17 Works concentrating on very high-resolution topographical guiding patterns for lamellar block copolymers are sparse.…”