TITANIUM CLUSTER POLYMERS AS REACTIVE ION ETCH BARRIERS

Titanium oxide films are barriers to the reactive oxygen etching of ph otoresists in silicon device fabrication. Medium-sized clusters of Ti oxide-alkoxide have been isolated by Klemperer et al. as intermediates in the formation of sol-gels from Ti tetraalkoxides and water. We rep ort that one of the clusters, Ti11O13 (OiPr)(18), reads with diols in hydrocarbon solvents to form network cluster polymers. These polymers form thin films of Ti-rich material that can be pyrolyzed to the anata se form of TiO2. Chemisorption of these cluster polymers onto the surf aces of poly(vinylbenzylphosphonic acid) copolymers (Macromolecules 19 95, 28, 110) gives thin coatings with significant etch resistance. A s equence of three depositions is sufficient to create an etch mask with 300:1 selectivity vs the untreated copolymers. Prospects for using th is chemistry in microlithographic patterning via surface imaging will be discussed.