SURFACE-REACTION OF ALTERNATELY SUPPLIED WF6 AND SIH4 GASES

The surface reaction of WF6 and SiH4 gases at similar to 100 degrees C was investigated using an ultraclean cold-wall LPCVD system with anal ysis by XPS and FT-IR. By supplying only WF6 onto the hydrogen-desorbe d Si(100) surface, which was prepared by preheating in Ar, dissociativ e adsorption of WF6 occurred generating WFx and Si-F was formed on the Si surface. On the HF-treated Si-dihydride surface, however, very lit tle adsorption of WF6 was observed. This means that adsorption of WF6 is enhanced by hydrogen desorption on the Si surface. Based on the res ults on the alternate WF6 and SiH4 supply experiments, it is proposed that SiH4 adsorbs on the WFx-adsorbed surface receiving F from WFx to become an Si-containing species, and further WF6 supply causes WFx ads orption accompanied with desorption of the Si-containing species. (C) 1998 Elsevier Science B.V. All rights reserved.