Electron-beam Directed Materials Assembly

Abstract

We have developed a processing method that employs direct surface imaging of a surface-modified silicon wafer to define a chemical nanopattern that directs material assembly, eliminating most of the traditional processing steps. Defining areas of high and low surface energy by selective alkylsiloxane removal that match the polymer period length leads to defect-free grating structures of poly(styrene-block-methyl methacrylate) (PS-b-PMMA). We have performed initial studies to extend this concept to other wavelengths beyond 157 nm. In this present paper, we will show that electron beam lithography can also be used to define chemical nanopatterns to direct the assembly of PS-b-PMMA films. Half-pitch patterns resulted in the directed assembly of PS-b-PMMA films. Electron beam lithography can also be used to prepare surfaces for pitch division. Instead of the deposition of an HSQ pinning structure as is currently done, we will show that by writing an asymmetric pattern, we can fill in the space with smaller lamellar period block copolymers to shrink the overall pitch and allow for 15-nm features.