A Simulation Study on Defectivity in Directed Self-assembly Lithography

Abstract

We have investigated the generation mechanisms of pattern defects in directed self-assembly (DSA) lithography using a simulation method based on self-consistent field theory (SCFT). The SCFT simulation results could reproduce grid defects, which are considered to be a kind of hexagonally perforated lamellar (HPL) metastable phase, as one of the characteristic pattern defects in the coordinated line epitaxy (COOL) DSA lithography process using polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA). We found that the grid defects were susceptible to be generated when a neutral layer was weakly attractive to PMMA block. Investigation of the PMMA segment node density profiles in the grid defects revealed that the terminal segments of the PMMA blocks indicated higher node density immediately above the neutral layer. These simulation results imply that the generation mechanism of the grid defects is strongly related with the interaction between the neutral layer bottom wafer and the terminal segment of the PMMA block.