T. Ogawa et al., SENSITIVITY-ENHANCED DRY DEVELOPMENT PROCESS FOR VUV AND EUV LITHOGRAPHY USING GRAFT-POLYMERIZATION, Microelectronic engineering, 30(1-4), 1996, pp. 287-290
The proposed dry development process uses the graft-polymerization of
Si-containing monomers to silylate the resist surface, thus enhancing
oxygen plasma etching durability. Single-layer and negative-tone resis
t patterns can thus be delineated with very high sensitivity. Grafting
sensitivity higher than that of wet-developed chemical-amplification
resist is obtained by using a Si-containing monomer having acrylic aci
d ester. This is confirmed through experiments using PMMA as the resis
t, 3-acryloxypropylmethyldimethoxysilane (APMS) as the monomer, and a
laser-plasma X-ray source for exposure. The dry-etching durability of
PMMA grafted using APMS is about four times that of ungrafted PMMA. FT
-IR measurements show that this is due to the resist-surface silylatio
n caused by the grafting. These results indicate the applicability of
this process to VUV and EUV lithographies.