Defect states at silicon surfaces

We demonstrate that surface defects can be characterized in terms of the sa me parameters that are used for studying bulk defects. We have a model for defect formation on the surface that allows us to estimate formation energi es. By combining our contactless surface recombination velocity (SRV) measu rement with ether surface analysis techniques, we are able to determine the electrical activity of many surface species. We demonstrate observation of surface dangling bonds created by O-2 dissolved in dilute hydrofluoric aci d (HF). Immersion in a methanol/I-2 solution is shown to produce electronic ally passive Si-OR bonds. Minority carrier capture cross sections for metal defects are calculated based on independent measurement of metal surface c overage. Through the understanding of surface defects, we apply our lifetim e measurement to monitor metal contamination from dilute HF solutions. A mo del relating metal deposition rate to HF dilution is developed. We demonstr ate sensitivity of 20 parts per trillion (ppt) Cu in a 500:1 HF solution. ( C) 1999 Elsevier Science B.V. All rights reserved.