Effects of resist sidewall morphology on line-edge roughness reduction and transfer during etching: is the resist sidewall after development isotropic or anisotropic?

摘要

Measurements of the sidewall morphology of commercial resist lines (3-D line-edge roughness) after lithography and before etching by critical dimension atomic force microscopy (CD-AFM) and scanning electron microscopy show that they exhibit anisotropy in the form of striations perpendicular to line direction. When this anisotropy of postlithography resist sidewalls is included in the models for trimming and pattern transfer proposed in an earlier paper [Constantoudis et al., J. Micro/Nanolith. MEMS MOEMS 8(4), 043004 (2009)], the models predict the beneficial role of trimming process in line-edge roughness reduction during pattern transfer, in agreement with experimental results. Furthermore, experimental and simulation studies show that the CD-AFM measurements of the 3-D line width roughness may overestimate the correlation length. Taking into account this finding in the model for trimming, we find that model predictions further approach the experimental results.