Characterization of acrylic copolymers applied in negative‐type photoresist via a ternary composition diagram

Abstract

Abstract Three‐component acrylic copolymers used as a binder for negative‐type photoresists were synthesized and characterized. First, free radical polymerization was employed to synthesize two‐component binders, i.e., acrylic ester copolymers with different ratios of benzyl methacrylate (BZMA) and methacrylic acid (MAA). Thermal behavior, viscosity and molecular weight of the prepared two‐component binders were studied. Then, a series of three‐component binders were prepared through incorporation of another monomer, 2‐hydroxyethyl methacrylate (2‐HEMA). FTIR was used to examine the evolution of chemical bonds at various stages of the synthetic process. Thermal analyses, TGA and DSC, were used to evaluate the level of enhancement on thermal stabilities of the prepared three‐component binders. Finally, an optimal region in the ternary composition diagram of BZMA, MAA, and 2‐HEMA can be identified by comparing the results of acid value, viscosity, and molecular weight of the binder. A negative‐type photoresist was prepared using an optimized composition, for which resolution of the circuit could reach the level of 6 μm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008