Reduction of line edge roughness in the top surface imaging process

This article presents a novel top surface imaging (TSI) process that is highly sensitive and reduces line edge roughness (LER). We found that LER and residue decreased when we used a chemically amplified (CA) resist, consisting of a base polymer with a high molecular weight and a photo-acid generator producing an acid with a high molecular weight. The top thin silylated layer of the exposed region on the CA resist causes the LER. A breakthrough step in the dry-development process improves the silylation contrast between the exposed and unexposed regions. We then apply a novel step in the dry-development process which involves a predry development bake at a temperature above the glass transition temperature of the silylated polymer. This step is effective in rolling and smoothing the edge of silylated layer by thermal flow. By applying the predry-development bake step above the glass transition temperature, we were able to reduce the LER to less than 6 nm. We have demonstrated a novel TSI process for achieving highly sensitive and improved LER; (C) 1998 American Vacuum Society. [S0734-211X(98)09506-7].