Influence of polymer phase separation on roughness of resist features

Abstract

The dependence of roughness of poly͑methylmethacrylate͒ resist features on developer composition and development time, using methyl isobutyl ketone:propanol ͑MIBK:IPA͒ developer with and without ultrasonic assistance, is investigated using atomic force microscopy. It is found that the roughness decreases with increasing proportion of MIBK in the developer and that for a weak developer ͑1:4 MIBK:IPA at 25°C͒, the roughness increases with development time. Ultrasonically assisted development is also found to reduce the roughness when using a weak developer, but has no significant effect with a strong developer ͑1:1 MIBK:IPA͒, or when using 3:7 water:IPA. We propose that the origin of the roughness is due to phase separation during development in weak solvents and for long development times.

The Interdependence of Exposure and Development Conditions when Optimizing Low-Energy EBL for Nano-Scale Resolution

“…In these cases, the grating is partly or entirely destroyed by redistribution of PMMA that tends to form islands at irregular locations. Similar morphologies have been reported in the literature for PMMA uniformly exposed to electrons and then developed (Hasko et al, 2000;Yasin et al, 2004). It is well known that formation of globular islands or percolation networks may occur in immiscible liquids that undergo a phase separation generating such morphologies as seen in Fig.…”

“…Furthermore, the detailed molecular processes occurring during dissolution of the most useful resists have been under-addressed if not overlooked so far. As a consequence, understanding of the trends of resist development currently resides mostly on published experimental results (Cord et al, 2007;Dial et al, 1998;Ocola & Stein, 2006;Yan et al, 2008;Yasin et al, 2002;Yasin et al, 2004). Within the last decade, numerous research groups have invested a significant effort to explore experimentally the resolution limits o f d e e p n a n o s c a l e E B L .…”

A review of line edge roughness and surface nanotexture resulting from patterning processes

“…It takes into account the molecular structure of the photoresist, the photoacid generator presence, its initiation, diffusion and reaction to create deprotected sites as well as the dissolution of the exposed areas using a quasistatic fast dissolution algorithm [32][33][34]. Excellent process simulation and experimental studies have also appeared in the literature for the process effects on LER, such as aerial image contrast [35][36][37], shot noise [38], development process [39][40][41][42][43], lithographic process conditions [44][45][46][47][48], lithographic materials [32,33,[49][50][51][52][55][56][57][58][59] and others. Our simulation results are consistent with these studies.…”

Correlation of lithographic performance of the electron beam resists SML and ZEP with their chemical structure

“…9 The bell-shaped curve of the RMS roughness versus e-beam dose arises due to the different rate of phase separation occurring at various exposure doses. 10 Since SML and ZEP show similar bell shaped curves, the phase separation processes in both resists taking place during development may be similar to that of PMMA; however, the mechanisms might differ because of the different developers used.…”