Study of Resist Pattern Roughness on 0.15 .MU.m KrF Lithography.

Abstract

Resist pattern edge roughness of a chemically amplified resist for 0.15μm KrF excimer laser lithography has been studied. The linewidth 3σ critical dimension (CD) dispersion of the chemically amplified positive working resist increases significantly from 3.0nm to 18.5nm upon reduction of the film thickness for the 0.15μm isolated line pattern, and shows pattern size dependence. After the gate etching process, the pattern edge roughness was almost the same as the linewidth 3σ CD dispersion on the resist film before the etching. From gas chromatography-mass spectrometry (GC-MS) analysis of the residual solvent in the resist film, the solvent density was found to decrease as the film thickness decreased. The relationship between residual solvent density and linewidth 3σ CD dispersion for the 0.15μm pattern before and after the etching process was observed. From the process condition dependence investigation, it was determined that the resist pattern edge roughness could be reduced by optimizing the baking conditions mainly determined by the prebake temperature.