Abstract: Copolymers are made by reacting maleic anhydride or a related compound with a 4-vinyl-1,3-dioxolane in the presence of a free radical initiator. The dioxolane reactant can be made by reacting a ketone with 3,4-epoxy-1-butene, or a substituted derivative thereof.

Abstract: Copolymers are produced when 3,4-epoxy-1-butene (EpB) is coplymerized with maleic anhydride. The copolymerization is initiated by free radicals, and comprises both 1,2-propagation and 1,5-propagation of EpB. When an ether is used as the reaction solvent, the product is soluble, and essentially composed of (a) a monomer derived from maleic anhydride, and (b) two monomers derived from EpB. When the reaction solvent is a ketone, the polymer product is also soluble, and additionally contains (c) a moiety derived from a dioxolane formed in situ. When the reaction is conducted in the presence of a non polar (e.g., hydrocarbon or a halocarbon) solvent, or neat (i.e., in the absence of a solvent), the polymer product is insoluble in common organic solvents and contains (d) a symmetrical EpB dimer. This dimer apparently does not form, or is formed to only a very slight extent, when the polymerization is conducted in polar reaction solvents.

Abstract: Positive-working photoresist elements are protected against reflection of activating radiation from the substrate by incorporation of certain butadienyl dyes in a photoresist layer, an anti-reflective layer or a planarizing layer. These dyes have superior resistance to thermal degradation or volatilization at temperatures of as high as 200.degree. C. or more. The dyes also exhibit good solubility in solvents commonly employed in processing semiconductor devices, thus permitting the dyes to be incorporated in photoresist elements in an amount sufficient to prevent resist image distortion caused by backscattered or reflected light.