Alkyl radical involvement in silicon surface chemistry

Abstract

The reaction of Si(100)-(2 × 1) with C 3H 6 has been observed to increase with the addition of atomic hydrogen to the C 3H 6 overlayer. The enhancement in reactivity is postulated to originate from a free radical process involving the creation of the chemisorbed propyl species. The propyl species is bound to free valencies on the Si(100). The increase in reactivity is shown in two ways. First, the thermal desorption yield of C 3H 6 decreases with increasing exposures of atomic hydrogen to the C 3H 6-covered Si(100). Second, measurements of the C(KLL) Si(LVV) Auger peak-to-peak ratio before and after thermal desorption show that more carbon remains on the surface after C 3H 6(ads) interaction with H. The ability to control the reaction of a hydrocarbon molecule with a semiconductor surface has several implications for processes of chemical vapor deposition (CVD), plasma vapor deposition (PVD), and reactive ion etching (RIE).