Recent advances in chemically amplified resist materials

Abstract

The design of resist based on the principle of chemical amplification has provided imaging materials with remarkable sensitivity. These materials function on the basis of photo-generation of a latent image of catalyst. In a subsequent step that is usually thermally activated,the catalyst acts on some part of the formulation to modify the solubility of the film. In most cases reported to date,the systems depend on acid that is generated by the irradiation of an ever growing list of neutral compounds which produce acidic radiolysis products. Acid catalysis of side chain cleavage,cross-linking via electrophilic aromatic substitution and hydrolysis of acetals, silyl ethers and ketals are but a few of the reactions that have been exploited in the design of acid catalyzed,chemically amplified resists. The use of photobase generators for the design of such systems is relatively rare. Radiolysis of certain cobalt amine salts has been used to catalyze epoxy curing. Recent developments that provide ready access to photo-generated amines via the corresponding activated carbamates have been exploited in the design of photosensitive polyimide formulations and as a component of an interesting imaging systems that includes both a photobase generator and a thermal acid generator. We now report our work on the use of photo-generated base in the design of fine line resists that derive high sensitivity from base catalyzed chemical transformations. A variety of base catalyzed reactions have been auditioned for this application. The results of these studies have provided high sensitivity resists that can be developed with aqueous base or silylated and dry developed with oxygen RIE.