Three-component photoresists based on thermal crosslinking and acidolytic cleavage

Abstract

Three vinyl ether monomers, 2,2-bis(4-[2′-(vinyloxy)ethoxy]phenyl(propane, 1,3,5-tris[2′-(vinyloxy)ethoxy]benzene, and 1,1,1-tris(4-[2′-(vinyloxy)ethoxy]phenyl)-ethane were synthesized and studied as thermal crosslinking agents in a three-component chemically amplified photoresist system. During prebake the resists were completely insolubilized in aqueous base through thermal crosslinking between poly( p-hydroxystyrene) binder polymer and the vinyl ether monomers. Upon exposure to UV and subsequent postexposure bake, the crosslinks were cleaved by photogenerated acid, leading to effective solubilization of the exposed areas. The thermal crosslinking and acid-catalyzed cleavage of the crosslinks were investigated by infrared (IR) spectroscopy. Degree of conversion of vinyl ether groups, dissolution rate and photosensitivity of the resists are strongly dependent on prebaking temperature. The resists showed relatively high sensitivity at 365 nm, and afforded positive-tone images by alkaline development.