SENSITIVITY-ENHANCED DRY DEVELOPMENT PROCESS FOR VUV AND EUV LITHOGRAPHY USING GRAFT-POLYMERIZATION

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.