Advanced epoxy novolac resist for fast high-resolution electron-beam lithography

Aspects of the formulation of a highly sensitive cresol epoxy novolac-based chemically amplified negative resist (epoxy resist, EPR) and optimization of critical process parameters for high-resolution electron-beam lithography are reported. The bulk resist sensitivity (E(80), dose for 80% thickness retention) is 0.9 mu C cm(-2) at 40 kV. The effect of postapply bake and postexposure bake on resist sensitivity, contrast and resolution are investigated and optimized for lithography up to the 0.1 mu m regime, The resist process is characterized by a good exposure dose latitude and relevant insensitivity to the variation of thermal processing conditions. Postexposure bake temperature variations in the 90-130 degrees C range cause minimal change in sensitivity but remarkable change in contrast. Due to this behavior the resist process is not described satisfactorily by the reaction kinetic models commonly used to characterize chemically amplified resists of different chemistry. (C) 1995 American Vacuum Society.