Process Characterization of Bi-layer Silylation Process for 193-nm Lithography

Abstract

We have been evaluating the bi-layer silylation process for 193-nm lithography as one of the top surface imaging (TSI) technologies to improve lithography performance. In this paper, we focus on the effect of process intervals for the bi-layer positive-tone silylation process. We found that the effect of the process interval between the post-exposure bake (PEB) and the silylation treatment was remarkable, but the effects of other process intervals were not serious in our evaluation. The critical dimension (CD) of L/S patterns was enlarged by the process interval after the PEB. However, by the application of a thermal treatment prior to the silylation treatment, we could control the CD fluctuations of the L/S patterns. Moreover, we found that pattern collapses were generated by the effect of corrosion after the dry-development. When we applied an optimized C₂F₆/O₂ plasma treatment as a corrosion prevention treatment, we could obtain fine patterns after the dry-development. We confirmed the high reliability of this bi-layer silylation process for practical applications.