Oxidation of Single‐Crystal Silicon Carbide: Part I . Experimental Studies

Abstract

The oxidation of single crystal SiC in dry oxygen (10-3-1 atm and 1200~176 followed parabolic kinetics. Two different apparent activation energies were calculated for oxidation of the (0001) C faces of SiC, approximately 120 k J/tool below 1350~ and 260 kJ/mol above 1350~ Two regimes were not apparent for oxidation of the (0001) Si faces, and apparent activation energies lay between 223 and 298 kJ/mol. Double oxidation experiments using 1~O2 and 1802 indicated that the process is dominated by the transport of molecular oxygen at lower temperatures (< 1300~ with a substantial contribution from diffusion of ionic oxygen at higher temperatures. Epitaxially grown Si 13C films on alpha-Si 12C substrates via CVD were used to study carbon transport behavior during oxidation of SiC. Depth profiles for carbonaceous species using SIMS showed that carbon can transport quickly through the oxide layer, which eliminates the possibility that transport of carbonaceous species is rate controlling in the oxidation of SiC. Oxidation mechanisms of SiC are discussed on the basis of these results.

Oxygen partial pressure dependence of the SiC oxidation process studied by in-situ spectroscopic ellipsometry

“…From these considerations, as well as the fact that R 1 is proportional to p, the gentle deceleration of the oxide growth rate can be attributed to the accumulation of Si and C interstitials near the interface, and given approximately as dX/dt $ R 1 exp(-X/L 1 ), which is coincident with the second term in Eq. (4).…”

“…[3][4][5][6] These reports have pointed out that SiC oxidation can be basically described by the Deal-Grove model, proposed for the explanation of Si oxidation. 7 Contrary to these previous results, our recent studies using in-situ spectroscopic ellipsometry [8][9][10] as well as ex-situ measurements 11 showed that the oxide growth rates in a thin oxide regime are higher than those predicted by the DealGrove model, similar to the case of Si oxidation.…”

“…4,11 However, both of these studies did not examine the initial oxidation process in detail, partly because in-situ real-time observations were not possible. We performed in-situ real-time measurements at reduced partial pressures between 0.1 and 1.0 atm, and found the presence of the initial growth rate enhancement to be similar to the case at atmospheric pressure.…”

Theoretical investigation of carbon defects and diffusion in α-quartz

“…There are also experimental indications 3 that during oxidation of SiC the outdiffusion of carbonaceous species is a fast process. The oxidation rate has been thought to be limited by the indiffusion of oxygen.…”

Corrosion of Ceramic Materials

“…Ramberg et al (1996) have studied the oxidation of pure SiC in the temperature range of 800-1100°C and shown that the linear reaction rate limits the oxidation rate in this temperature range. At temperatures of 1200°C and higher, the oxidation kinetics are generally considered purely parabolic (Costello and Tressler, 1986;Zheng et al, 1990a;Ogbuji and Opila, 1995). As first noted by Motzfeldt (1964), the parabolic rates of SiC should be 1.5 to 2 times slower than Si due to the additional oxygen consumed in the formation of gaseous products by the reactions:…”