POLYMERIZATION OF N-(TERT-BUTYLDIMETHYLSILYLOXY)MALEIMIDE AND APPLICATIONS OF THE POLYMERS AS RESIST MATERIALS

A new silicon-containing maleimide monomer, N-(tert-butyldimethylsilyl oxy) maleimide (SiOMI) has been synthesized. SiOMI was radically copol ymerized with styrene derivatives (XSt) to obtain alternating copolyme rs, P(SiOMI/XSt), in high conversions. The copolymers have high glass transition temperatures above 190 degrees C, and the tert-butyldimethy lsilyloxy groups are thermally stable up to 300 degrees C. The SiOMI u nits in the copolymers were converted into N-hydroxymaleimide (HOMI) u nits by acidolytic deprotection of the tert-butyldimethylsilyloxy prot ecting groups. The facile deprotection of the side-chain tert-butyldim ethylsilyloxy groups from the protected copolymers provided a signific ant change in solubility of the polymers due to the large polarity cha nge. Submicron positive-tone images were obtained from the copolymers containing an onium salt as a photoacid generator by irradiation with electron beam and development with alkaline solutions. The polymer fil ms also showed very high oxygen plasma etch resistance compared with n ovolac resins. The silicon-containing maleimide polymers were found to have required properties, such as good alkaline solubility after depr otection, superior adhesion, low optical density, high thermal stabili ty with high T-g, and high plasma etch resistance for applications as deep ultraviolet and electron beam resist materials. (C) 1997 John Wil ey & Sons, Inc.