NEW SILICON-RICH SILYLATING REAGENTS FOR DRY-DEVELOPED POSITIVE-TONE DEEP-ULTRAVIOLET LITHOGRAPHY

Disilanes are used as silylating reagents for near-surface imaging with deep ultraviolet (248 nm) light. A relatively thin imaging layer of a photocross-linking resist is spun over a thicker layer of hard-baked resist which functions as a planarizing layer and antireflective coating. Photoinduced acid generation and subsequent heating cross-links exposed areas and renders them impermeable to an aminodisilane which reacts with the unexposed regions. Subsequent O2 reactive-ion etching affords a positive-tone image in the resist. The use of disilanes introduces a higher concentration of silicon into the polymer than is possible with silicon reagents that incorporate only one silicon atom per reactive site. The higher silicon content in the silylated polymer increases etching selectivity between exposed and unexposed regions and thereby increases the contrast. We have resolved high-aspect ratio, 0.25 mum line and space patterns with 248 nm light in a stepper with a numerical aperture=0.48.