Redistribution of Dopant and Impurity Concentrations during the Formation of Uniform WSi2 Films by RTP

摘要

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 ohms/cm wafers. The substrates were chemically etched, followed by an RF sputter deposition of 710A Tungsten metal. The samples were then fast radiatively processed in an RTP system for time intervals ranging from 15 to 45 seconds at high temperature (approx. 1100C) 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 Tungsten Silicide 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 Fluorine, Chlorine, Sodium, Potassium, Carbon and Chromium have also been detected. Keywords: Ptyre semiconductors, Very large scale integrated circuits, Reprints. (aw)