Development of SSQ Based 157 nm Photoresist [ 1 ]

Siloxane/silsesquioxane (SSQ) and fluorocarbon` materials have been identified to be relatively transparent at 157 nm. While the main stream of material research effort has been focused on the synthesis of fluorocarbon polymers, we have made significant progress on developing silsesquioxane polymers for 157 nm photoresist application. Our current SSQ based photoresists (a, s, and 8 type shown in this paper) have absorbance value ranging from 3.4 to 2.5 μm"' . With a 1200 A thickness, a type has demonstrated 60nm L/S using a 0.85 NA F2 Exitech tool with an alt-PSM and c and 6 type have demonstrated 75nm L/S using a 0.60 NA tool. a type resist patterns (L/S) have been successfully transferred down to underlying spin-on carbon hard mask (HM) using N2/02 RIE. Progress also has been made on reducing the absorbance of SSQ polymers. A new ?. type SSQ polymer showed absorbance value of 1.66 μm'. The design concept and physical properties of synthesized SSQ polymers are presented. Lithographic performance of SSQ based resists is also discussed.