Chemically amplified imaging materials based on acid-catalyzed reactions of polyesters or electrophilic crosslinking processes.

Abstract

The design of chemically amplified imaging systems based on acid catalyzed thermolytic cleavage of polymer main-chains has been exploited with a variety of structures containing tertiary, allylic, or benzylic ester groups. In all cases, the esters have been designed for their ability to undergo facile thermolytic elimination. This report outlines the preparation, study, and imaging of several polyesters containing thermolytically active moieties. These new acid labile polyesters have been incorporated into two-component imaging materials for which radiation sensitivity is due to the presence of compounds which produce acid upon irradiation. The photogenerated acid is then used to catalyze thermolytic cleavage of the polyester main-chain in a process which does not consume the acid and therefore provides for chemical amplification. Imaging is possible using a variety of radiation sources, from deep-UV to X-rays. The concept of imaging through multiple main-chain cleavage is important as it can lead to self- or dry developing images. In the present study, only partial self-development was observed as one of the diacid liberated by the chain cleavage process was not volatile. A second family of radiation sensitive imaging materials has also been designed based on the catalyzed electrophilic crosslinking of polymers containing aromatic rings. While this new approach is only illustrated here for systems in which crosslinking involves polymer pendant groups, the same design is also applicable to polymer main-chains. This family of crosslinkable, chemically amplified, resist materials shows very high sensitivities of ca. 1mJ/cm2 for exposure in the deep-UV, ca. 1μC/cm2 for E-beam exposure, and ca. 12-15mJ/cm2 for X-ray synchrotron radiation.