Molecular glass resists developable in supercritical carbon dioxide for 193 nm lithography

In order to meet the growing demand for smaller and higher-performance microelectronic devices, attention has been focused on developing molecular glass photoresists which can be employed under next-generation 193-nm immersion lithography conditions. These amorphous organic compounds produce high-resolution patterns due to their smaller pixel size and lack of chain entanglement compared with polymer photoresists. Specially designed molecular resists have substantial solubilities in supercritical carbon dioxide (scCO2) which can be altered through acid-catalyzed deprotection reactions. While molecular resists based on phenols have been demonstrated for high-resolution patternability, scCO2- developable molecular materials have not yet been reported for 193-nm lithography. In this paper, we introduce alicyclic materials based on naturally occurring backbones as chemically amplified molecular resists developable in scCO2. Methylated β-cyclodextrin and cholic acid derivatives with acid-labile protecting groups form good amorphous thin films with high glass transition temperatures (>100 °C). These molecules show the capability of being patterned and developed in scCO2 with resolution below 200 nm.