Application of Polysilanes to LSI Manufacturing ProcessesTheir Antireflective Properties and Etching Selectivity toward Resists

Fundamental aspects for a novel LSI pattern fabrication process employing polysilanes as an antireflective layer (ARL) are discussed. The multilayer is composed of an organic resist, a polysilane layer, and a substrate. The polysilane avoids reflections from the substrate when the resist is exposed to 248-nm light emitted from a KrF excimer laser. It also acts as a pattern transfer layer. The polysilane layer is etched faster than the resist when the etching is carried out with reactive ions by employing Cl 2 gas. Therefore, the resist pattern is transferred to the polysilane layer precisely. The relationship between the structure of the polysilane and its physical properties, namely, the UV absorbance at 248 nm and etching selectivity toward the organic resist, is discussed and the best polysilane structure for this application identified.