Patent ID: 6042990
Filing Date: 2000-03-28
Classification: C09D,G03F,Y10S

Abstract:
A method for making a thermosetting anti-reflective coating composition exhibiting an etch selectivity to novolac- and poly(hydroxystyrene)-based photoresists greater than 1.0 under oxygen plasma etch conditions, said method comprising:a. forming a light-absorbing, hydroxyl-functional, highly aliphatic polyester resin by condensation methods; andb. purifying said polyester resin by removal of residual solvents, starting materials, by-products, and impurities from the resin by applying heat and/or vacuum; and/or by dissolving said polyester resin in a water-soluble solvent and precipitating the mixture into a large volume of acidified water, after which the precipitated resin is collected and dried; andc. combining said polyester resin with an alkylated aminoplast crosslinking agent and a protonic acid curing catalyst in a low-to-medium boiling solvent system wherein alcohol comprises at least 20 weight percent of the solvent system; and the overall formulation having a total solids content of about 3 to about 10 weight percent;whereby the anti-reflective coating composition so formed can be applied by spin coating onto semiconductor substrates and then baked at temperatures in the range 120.degree. C.-225.degree. C. to obtain a uniform, crosslinked film which exhibits high optical density at a target exposing wavelength and shows no intermixing with a subsequently applied photoresist.