We have been studying an advanced top surface imaging (TSI) process for 157-nm lithography that approaches 100-nm or smaller pattern fabrication. As the advanced TSI process, we are evaluating a new bi-layer silylation process by applying a vapor phase silylation treatment after an alkaline wet-development of the top layer (SIL YAL). There are several advantages to this process, such as a poly-vinyl-phenol (PVP)-type chemical amplified (CA) resist application, defect control by wet-development, and pattern inspection capability after wet-development. However, due to the resist thermal flow during the silylation, the resolution capability and critical dimension (CD) control ability are limited. We have optimized the silylation conditions and applied a UV cure treatment before silylation in order to control the resist pattern profile. By controlling the pattern profiles after the silylation treatment, we could fabricate 110-nm L/S and 100-nm C/H patterns using the SIL YAL process for 157-nm lithography.