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 (scCO ₂) which can be altered through acid-catalyzed deprotection reactions. While molecular resists based on phenols have been demonstrated for high-resolution patternability, ScCO ₂developable 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 ScCO ₂. 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 ScCO ₂ with resolution below 200 nm.