During the last several years image reversal has been demonstrated to be an effective technique for
extending theresolution ofoptical steppers while maintaining therelative simplicity of single layerresist
processing13. In order to satisfy the increasing requirements for smaller device geometries very high
numerical aperture g-line steppers have lately become available. A new image reversal resist (Raypo)
designed specifically for g-line use has recently been developed by Hoechst corporation4. This paper
discusses the process optimization andlithographic performance ofthis resist on a 0.54 N.A. stepper, one
ofthe highest numerical aperture g-line steppers currently available. The process variables investigated
include prebake temperature, post exposure bake temperature, flood exposure time, and develop conditions.
The responses studied include resolution capability, profile quality, dose requirements, exposure
latitude, focus latitude, and performance on reflective topography. The thermal stability of the resist is
also discussed. Some results are compared with those for a new advancedpositive g-line resist (AZ 6212)
developed by Hoechst corporation.