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

Disilanes are used as silylating reagents for near-surface imaging wit h 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 coat ing. Photoinduced acid generation and subsequent heating cross-links e xposed areas and renders them impermeable to an aminodisilane which re acts with the unexposed regions. Subsequent O2 reactive-ion etching af fords a positive-tone image in the resist. The use of disilanes introd uces a higher concentration of silicon into the polymer than is possib le with silicon reagents that incorporate only one silicon atom per re active site. The higher silicon content in the silylated polymer incre ases etching selectivity between exposed and unexposed regions and the reby 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 nume rical aperture=0.48.