Secondary ion mass spectroscopy has been used to study the effects of rapid thermal processing on the formation of tetragonal tungsten disilicide thin films on Si(100), p-type 5 Omaga;, cm wafers. The substrates were chemically etched, followed by an RF sputter depostion of 710Å W metal. The samples were then fast radiatively processed in an RTP system for time intervals ranging from 15 to 45 seconds at high temperature (∼1100°C) under high vacuum.
The redistribution of the boron dopant concentration profile is studied and shows that boron moves from the Si-substrate into the growing Wsi2 film, eventually escaping into the vacuum. Oxygen is the major impurity in these samples and its removal from the interface has been shown to improve the quality of the silicide film. Trace quantities of F, Cl, Na, K, C and Cr have also been detected.