Organic Materials Challenges for 193 NM Imaging

Photolithography using 193 nm radiation is the leading candidate for the manufacture of 0.18-0.13 micron design rule devices. The optical absorption of materials such as novolacs, and functionalized poly(hydroxystyrenes) and styrene-acrylate copolymers, which are the matrix materials of choice for G line, I line, and 248 nm lithography, is significantly higher than one at 193 nm making them too opaque to be useful at this shorter wavelength. The opacity of the current photoresists at 193 nm requires innovation in designing alternative materials and processes to realize the full potential of 193 nm (ArF) lithography. From a materials standpoint, this challenge must be addressed by new chemistries and process schemes capable of providing resists with the aqueous base solubility, etching resistance, resolution, photospeed, and process latitude required for large- scale manufacturing. Chemical alternatives aimed at these issues will be described and discussed.