Application of polysilanes to LSI manufacturing processes - Their antireflective properties and etching selectivity toward resists

Fundamental aspects for a novel LSI pattern fabrication process employing p olysilanes as an antireflective layer (ARL) are discussed. The multilayer i s composed of an organic resist, a polysilane layer, and a substrate. The p olysilane 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. There fore, the resist pattern is transferred to the polysilane layer precisely. The relationship between tile structure of the polysilane and its physical properties, namely, the UV absorbance at 248 nm and etching selectivity tow ard the organic resist, is discussed and the best polysilane structure for this application identified.