Polysilyne resists for 193-nm excimer laser lithography

Polyalkylsilynes have been used as resists for 193-nm projection lithography. These resists can be either wet developed using toluene or dry developed using HBr reactive ion etching (RIE). Wet development relies on crosslinking via intermolecular Si-O-Si bond formation to reduce solubility (negative tone) whereas the dry development relies on photooxidation to induce etch selectivity (also negative tone). The sensitivity in either case ranges from 20 to 200 mJ/cm² and depends on the resist formulation. The best resist compositions are those that contain predominantly small (n-butyl) aliphatic pendant groups rather than large (cyclohexyl, phenyl) pendant groups. Using a 0.33 NA catadioptric lens with a phase mask, equal line-and-space features as small as 0.15 μm have been printed and transferred through 1.0 μm of planarizing layer (aspect ratio >6) using oxygen RIE.