Monte Carlo simulation of gel formation and surface and line-edge roughness in negative tone chemically amplified resists

Abstract

Simulation of amine concentration dependence on line edge roughness after development in electron beam lithography J. Appl. Phys.Surface and line-edge roughness in solution and plasma developed negative tone resists: Experiment and simulation J.A molecular-based representation of a negative tone chemically amplified resist was developed and studied using stochastic simulations. The gel formation mechanism resulting from the reactiondiffusion phenomena in the polymer matrix during the postexposure bake step, as well as the surface and line-edge roughness formation were investigated in two dimensions. Graph theory computational techniques were employed to determine the gel cluster size and its relation to the fraction of the total number of chemically and physically cross-linked chains. Results of the simulation include the maximum acid diffusion range, the cross-link density, the surface and line edge roughness, versus exposure dose and photoacid generator concentration.

Effects of Photoresist Polymer Molecular Weight and Acid-Diffusion on Line-Edge Roughness

“…A stochastic dissolution simulator built to model reactiondiffusion phenomena in negative tone chemically amplified resists, [10][11][12] was modified accordingly, in order to simulate positive tone resist deprotection chemistry and dissolution. 9,13) Dissolution modeling was based on the notion of critical ionization fraction 14) and was combined with the code for modeling polymer chains, and postexposure bake.…”

Material and process effects on line-edge-roughness of photoresists probed with a fast stochastic lithography simulator

“…[32][33][34][35][36][37][38] Probabilisticlike models also find applications, 39 as well as variants of the percolation dissolution, such as the aggregate extraction dissolution model. The rate of dissolution of the resist film is controlled by the diffusion of base through a so-called "penetration zone."…”

Monte Carlo study of surface and line-width roughness of resist film surfaces during dissolution

“…However, the same effect is accompanied by resist line profile distortion, especially in the resist/line case [32,38]. Simulations [5] have also predicted the same, and this has been justified in terms of the acid diffusion, which softens the difference in exposure between neighboring regions of the resist line to the intermediate region between exposed and un-exposed film. It has been reported that the use of low molecular weight and low dispersivity polymers as resist films decreases roughness and acid diffusion range [39].…”

“…In this article the simulation of positive tone resists, is done along the same lines with previous work [5]. All polymer chains have the same polymerization length, which is given as input in the simulations.…”

“…In previously published work a simulator was described that was able to determine the gel fraction in terms of exposure dose in negative tone chemically amplified resists [5]. Negative tone resists become insoluble in the regions exposed in radiation and therefore produce the negative of the mask used to expose them.…”