An integrated growth and analysis system for in-situ XAS studies of metal-semiconductor interactions

A UHV system for in-situ studies of metal-semiconductor interactions has been designed and assembled at North Carolina State University and recently installed and tested at the NSLS. The UHV system consists of interconnected deposition and analysis chambers, each of which is capable of maintaining a base pressure of approximately 1 x 10(-10) Torr. Up to three materials can be co-deposited on 25 mm wafers by electron-beam evaporation. Substrate temperature can be controlled in the range 30-900 degrees C during deposition, and the growth process may be monitored with RHEED. The deposited materials and their reaction products can be studied in-situ with a variety of technique: XAFS, AES, XPS, UPS and ARXPS/UPS. We describe the capabilities of the system and present our first EXAFS results on the stabilization of Co + 2 Si films co-deposited on Si0.8Ge0.2 alloys. Preliminary results indicate that Co + 2Si forms a stable film on Si0.8Ge0.2 with a ''CoSi2-like'' reaction path. As is the case with Co/Si0.8Ge0.2, silicide formation is complete at 700 degrees C. However, the Co + 2Si/Si0.8Ge0.2 system does not undergo a CoSi --> CoSi2 transition when annealed at 500-700 degrees C, and exhibits only weak CoSi features in this temperature range.