Soft X-Ray Induced Energy Deposition in a Three-Layered System: Au/C/PBS

An experimental and theoretical study of soft x-ray generated dose profiles in the Au/C/PBS three-layered system has been performed using x-rays from Al, Ag and Ti targets. Experimental measurements of etched photoresist thickness as a function of carbon layer thicknesses of several hundred Angstroms were performed. Theoretical dose profile calculations were made for the Al Kₐ, Ag Lₐ, and Ti Kₐ x-ray line energies using a 3-layer extension of the semiempirical electron transport model of Burke and Garth (1977) and Garth (1981). From the etch rate-exposure characteristic of PBS, predictions of the etched thickness vs carbon thickness were obtained and compared with the data. Qualitative agreement was obtained, but a quantitative discrepancy was found, attributable to the neglect of high energy bremsstrahlung-produced electrons in the theoretical model.