Reduction of line edge roughness in the top surface imaging process

This article presents a novel top surface imaging (TSI) process that is hig hly sensitive and reduces line edge roughness (LER). We found that LER and residue decreased when we used a chemically amplified (CA) resist, consisti ng of a base polymer with a high molecular weight and a photo-acid generato r producing an acid with a high molecular weight. The top thin silylated la yer of the exposed region on the CA resist causes the LER. A breakthrough s tep in the dry-development process improves the silylation contrast between the exposed and unexposed regions. We then apply a novel step in the dry-d evelopment process which involves a predry development bake at a temperatur e above the glass transition temperature of the silylated polymer. This ste p is effective in rolling and smoothing the edge of silylated layer by ther mal flow. By applying the predry-development bake step above the glass tran sition temperature, we were able to reduce the LER to less than 6 nm. We ha ve demonstrated a novel TSI process for achieving highly sensitive and impr oved LER; (C) 1998 American Vacuum Society. [S0734-211X(98)09506-7].