Aminodisilanes as silylating agents for dry-developed positive-tone resists for deep-ultraviolet (248-nm) and extreme ultraviolet (13.5-nm) microlithography

摘要

Abstract: Disilanes are used as silylating reagents for near-surface imaging with deep-UV (248 nm) and EUV (13.5 nm) lithography. A relatively thin imaging layer of a photo-cross-linking resist is spun over a thicker layer of hard-baked resist that functions as a planarizing layer and antireflective coating. Photoinduced acid generation and subsequent heating crosslinks render exposed areas impermeable to an aminodisilane that reacts with the unexposed regions. Subsequent silylation and reactive ion etching affords a positive-tone image. 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. The synthesis and reactivity of `smaller' disilanes, N,N-dimethylamino-1,2-dimethyldisilane, (DMADMDS), and N,N-diethylamino-1,2- dimethyldisilane also are described. Additional silylation improvements that minimize flow during silylation also are discussed including the addition of bifunctional disilanes to the monofunctional DMAPMDS. This causes the crosslinking to occur during silylation which minimizes flow. We have resolved high aspect ratio, very high quality 0.20 $mu@m line and space patterns at 248 nm with a stepper having a numerical aperture (NA) $EQ 0.53 and have resolved $LSEQ 0.15 $mu@m line and spaces at 13.5 nm. !24