IMIDE-DIMETHYLSILOXANE BLOCK-COPOLYMERS - DESIGN AND SYNTHESIS OF A PERMANENT BURIED OXYGEN-ION ETCH BARRIER

Imide-siloxane multiblock copolymers were investigated. A key feature of these copolymers is the preparation of bis(aminopropyl) oligomers v ia anionic ring-opening polymerization. The molecular weights of the o ligomers ranged from 1000 to 5000 g/mol. The oligomers were coreacted with 4,4'-oxydianaline (ODA) and pyromellitic dianhydride (PMDA) dieth yl ester chloride in a N-methyl-2-pyrrolidone/THF-solvent mixture in t he presence of N-methylmorpholine. The resulting amic ethyl ester silo xane copolymers were isolated and washed to remove homopolymer contami nation. Copolymer compositions, determined by H-1-NMR, ranged from 20 to 65 wt % siloxane content and the measured compositions were close t o those charged. Solutions of the copolymers were cast and cured (350 degrees C) to effect imidization, producing clear films. The films sho wed tough ductile mechanical properties with moduli varying with silox ane content. The copolymers displayed good thermal stability with deco mposition temperatures in the proximity of 450 degrees C. Multiphase m orphologies were observed irrespective of siloxane block lengths or co mpositions. (C) 1997 John Wiley & Sons, Inc.