Simulation of material and processing effects on photoresist line-edge roughness

Abstract

Sub-100 nm device fabrication rules require extremely tight control of Line-Edge Roughness (LER) of patterned structures. During lithographic processes the resist film introduces an initial LER due to its chemical structure and processing. This initial LER evolves during the subsequent etching step. A stochastic simulator is presented which takes into account material and process effects on photoresist LER. Its application in model cases reveals that LER decreases with lower degree of polymerisation, but is sensitive on the acid diffusion process during post exposure bake in Chemically Amplified Resists (CARs). Further simulations confirm that LER can be reduced during etch patterning, at the expense of critical dimension control.