Method of forming a pattern of silylated planarizing photoresist

Abstract

The invention provides an improved planarizing methodology for forming high-definition photolithographic masks of the type used in semiconductor integrated circuit manufacturing. A layer of planarizing photoresist is first applied to the surface topography of a semiconductor wafer substrate and shallow-penetrating radiation is then used to irradiate the surface of the photoresist. The radiation creates a blanket irradiated layer, adjacent the surface of the resist, consisting of an acid and resist in solution. The acid/resist solution readily absorbs and incorporates silicon. Next, the wafer is exposed to a silicon-containing compound, or softbaked in a silicon-containing environment, creating a silicon-enriched region adjacent the surface of the photoresist. An imaging resist is then applied to the resist, and a photolithographic mask is formed in the imaging resist. An etching step transfers the mask to the silicon-enriched region of the photoresist. The remaining areas of the silicon-enriched layer are exposed to an oxygen plasma which converts the silicon-enriched areas to silicon dioxide. The method of the invention produced high-definition mask lines and avoids the defect densities associated with conventional tri-layer processing using SOG.