The Effects of Vacuum Ultraviolet Radiation on the Processing of Electronic Materials

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

This project addresses materials science issues relevant to plasma processing of electronic materials. The aim is to combine Vacuum Ultraviolet Radiation (VUV) generation and analysis, plasma measurements, measurements of charge distributions stored in electronic materials with the development of a predictive model using Monte Carlo methods to obtain fundamental understanding of materials processing conditions. The approach is based on the hypothesis that exposure of electronic materials to (VUV) during processing has the potential to (1) beneficially deplete previously deposited charge, (2) affect the material adversely due to photoemissive, photoconductive or photo-injection processes, and (3) by eliminating the plasma entirely, produce a number of desired processing results without the need for exposure to plasmas, which can minimize the potential for charge-induced damage during processing. Specific tasks include: measure the effects of VUV exposure on previously charged wafers, both positively and negatively; measure the effects of VUV on test structures so as to determine whether VUV can be used to minimize the electron shading effect; separately vary the plasma and VUV flux densities impinging on an unpatterned wafer to determine the effects of the radiation on plasma treatment and the effects of plasma treatment on radiation exposure; evaluate the charging effects produced by VUV exposure during VUV processing of electronic materials; develop a Monte-Carlo predictive model for the separate and combined effects of VUV and plasma exposure. The project will utilize several processing reactors along with a synchrotron and/or localized plasma discharge VUV source so as to be able to vary the generation of VUV and plasma energy fluxes separately. Three specialized diagnostics will be utilized: (1) a Kelvin Probe which measures the charge distribution on both conducting and insulating surfaces, (2) an absolutely calibrated VUV monochromator to measure the VUV flux and spectrum generated by the reactors used in the project, and (3) Charm wafers, which monitor charge, current and UV (as distinguished from VUV) flux incident on the Charm wafer. The latter was selected as an industrially relevant monitoring system whose outputs can be compared directly with the Kelvin Probe and VUV monochromator. %%% This project addresses basic materials research issues in a topical area of materials science with significant technological relevance, and places emphasis on the integration of research and education. Connections between materials science, physics, and chemistry, along with electrical engineering are an important feature. This interdisciplinary approach impacts courses at the undergraduate and graduate levels, allows undergraduate and graduate students from different disciplines to participate effectively in the project, and to make presentations to multiple student groups. The project also has direct involvement of a local community college through active participation in research and education with emphasis on surface analysis aspects. The research program provides excellent student opportunities for hands-on experience in the use of sophisticated scientific equipment.