INFLUENCE OF PHOTO-ELECTRONS ON EXPOSURE OF RESISTS BY X-RAYS

Sensitivity and contrast ratio of PMMA resist were measured for Ti-K radiation ( lambda equals 0. 27 nm). We found a constant rate of solubility during development for exposed as well as for unexposed resists. This means that the process of solution is limited by diffusion and that the resist layer is homogeneously irradiated. Looking at the influence of substrate on exposure we found that the exposure time for gold substrate was only half of that with silicon substrate. This is, to a small part, due to x-ray fluorescence and mainly to photoelectrons. We also looked at the profiles of structures during development process and found that the resist behavior was similar for great areas as for fine structures.