Novel functional nortricyclene polymers and copolymers for 248- and 193-nm chemically amplified resists

We have designed and synthesized a series of novel non-acrylic nortricyclene polymer and copolymers containing various structural units for use in both 193 and 248 nm lithography. These polymers and copolymers are prepared using a free- radical cyclopolymerization process that is very versatile and allows use of a great variety of comonomers. The resulting materials exhibit outstanding dry-etch resistance, good adhesion to silicon, good transparency at 193 nm and, unlike many poly(norbornenes), they are not contaminated by metal catalysts. In preliminary 193 nm testing a resist formulated with a suitable photoacid generator afforded alkali-developed positive-tone images with sub-0.15 micrometer L/S resolution. Although a large array of copolymers are possible due to the ease with which the free-radical copolymerization reaction proceeds, copolymers based exclusively on functionalized norbornadiene and maleic anhydride-derived components have shown great promise. In particular, it is possible to tune their properties through simple variations in structure and composition.