Resist characterization: Procedures, parameters, and profiles

Abstract

Measurement systems for determining the exposure and development model are coupled with SAMPLE resist profile simulations to explore the impact of positive photoresist types, processing conditions, developer types, and resist lots on line edge profiles. The exposure system uses the optical transmission of a resist layer on a nonreflecting glass substrate as a function of exposure. A full spectrum, high intensity “hard” bleach is used to completely expose the photoactive compound. The companion development system uses optical interference through a transparent substrate to measure the development rate. The reproducibility of these systems and their accuracy compared to independent measurements are considered. These systems are applied to the problems of determining the critical prebake temperature at which thermal degradation occurs, exploring differences between developers, and making lotto -lot comparisons of resists. Parameter values for several resists are reported. The importance of the exposure and devel pment parameters is illustrated using the SAMPLE program. © 1982 SPIE.