Novel diastereomeric acrylic ketal monomers derived from (+)-camphor and (±)-camphor were synthesized. To investigate the applications of the camphor derivatives on positive-tone photoresists, the acrylic ketal monomers were copolymerized with methyl methacrylate, methacrylic acid, and n-butyl methacrylate. The optical activities of the chiral monomers and polymers were all evaluated. After UV irradiation and postexposure baking, the optical activity of the polymers decreased because of the decomposition of the acid-labile pendant chiral groups. The existence of alicyclic camphyl groups increased the etching resistance of the photoresists. The thermogravimetric properties of the copolymers, the exposure curves, the lithographic evaluation of the positive-tone photoresists, and the effects of alicyclic groups on the plasma etching resistance of the copolymers were all investigated. A resolution of a line- and-space pattern of 0.3 μm was achieved. Acid-catalyzed dehydration crosslinking was also found in this system. Sufficient UV irradiation and heat treatment could cause the acid-catalyzed dehydration crosslinking of pendant carboxyl groups and thereby increase the efficiency of the thermal resistance of the polymers.
All Science Journal Classification (ASJC) codes
- Surfaces, Coatings and Films
- Polymers and Plastics
- Materials Chemistry