Contamination Monitoring Using Surface Photovoltage and Application to Process Line Control

Abstract

AbstractSurface photovoltage (SPV) measurements of lifetime and charge are used by the silicon industry for real-time, non-contact monitoring of alkalide and heavy metal contamination during IC processing. Information about contamination present at the surface or in the bulk of a silicon wafer is derived from their effects on measured electronic characterization. Identification and detection, with a sensitivity of ppq (107 cm'3), of Fe and Cr in the bulk of p-type silicon is possible via monitoring of their decomposition/pairing kinetics with boron. We will show the most important examples of the application of SPV to monitor critical IC processing steps. The allowable contamination thresholds in IC processing lines are a very strong function of technology and are different for various metals.