Switching the Solubility of Polymers using Intermolecular Reactions and Diffusion of Small Molecules

A two-layer polymeric stack is designed to be converted to a three-layer stack via the diffusion of small molecules between layers. The three-layer stack is composed of a bottom layer carboxylic acid (CA-polymer) that is soluble in aqueous TMAH developer; a middle layer of reacted CA-polymer that became soluble in organic developer as a result of reaction with small molecules; and a top layer of nonpolar polymer that is soluble in organic developer. Several small molecules were evaluated for their effectiveness, by combing them with the CA-polymer and evaluated in their effectiveness in decreasing the solubility of this polymer in aqueous base. High molecular weight amines, benzyl bromide combined with nonnucleophilic base, dicyclohexylcarbodiimide, and diisopropylcarbodiimide all are capable of switching the solubility of the CA-polymer. These molecules were used in two-layer stacks to study diffusion, reaction and solubility change. The Tg of the CA-polymer was lowered to promote diffusion of the small molecule from the top to the bottom layers.