The etch rate, chemical reactions and etched surface of -silicon carbide are studied in detail using chlorine trifluoride gas. The etch rate is greater than 10 mm min À1 at 723 K with a flow rate of 0.1 ' min À1 at atmospheric pressure in a horizontal reactor. The maximum etch rate at a substrate temperature of 773 K is 40 mm min À1 with a flow rate of 0.25 ' min À1 . The steplike pattern that initially exists on the -silicon carbide surface tends to be smoothed; the root-mean-square surface roughness decreases from its initial value of 5 mm to 1 mm within 15 min; this minimum value is maintained for more than 15 min. Therefore, chlorine trifluoride gas is considered to have a large etch rate for -silicon carbide associated with making a rough surface smooth.

The etch rate of single-crystalline 4H–SiC is studied using chlorine trifluoride gas at 673–973 K and atmospheric pressure in a cold wall horizontal reactor. The 4H–SiC etch rate can be higher than 10 µm/min at substrate temperatures higher than 723 K. The etch rate increases with the chlorine trifluoride gas flow rate. The etch rate is calculated by taking into account the transport phenomena in the reactor including the chemical reaction at the substrate surface. The flat etch rate at the higher substrate temperatures is caused mainly by the relationship between the transport rate and the surface chemical reaction rate of chlorine trifluoride gas.

The etch rate of the polycrystalline β-silicon carbide (SiC) substrate in a wide range from less than one to more than ten µm/min is studied using chlorine trifluoride gas at concentrations of 10-100% in ambient nitrogen at 673-973K and atmospheric pressure in a horizontal reactor. The etch rate immediately increases at the substrate temperatures between 673 and 773K over the chlorine trifluoride gas concentrations used in this study. Additionally, the etch rate at higher than 773K is independent of the substrate temperature, similar to that at the chlorine trifluoride gas concentration of 100%. The etched surface tends to be smooth at high temperatures and high chlorine trifluoride gas concentrations. The polycrystalline β-SiC etch rate can be adjusted using the combination of the gas flow rate, chlorine trifluoride gas concentration and the substrate temperature in order to obtain surfaces suitable for various purposes.

Dry etching of 4H-silicon carbide (SiC) is studied using chlorine trifluoride gas at 673-973K and atmospheric pressure in a horizontal reactor. The etch rate of C-face and Si-face of 4H-SiC can be greater than 10 um/min at substrate temperatures higher than 723 K. The etch rate of Si-face is lower than that of C-face. The etch rate increases with the chlorine trifluoride gas flow rate. The etched surface of Si-face shows many pits having a hexagonal edge shape and tends to be rough. However, the C-face maintains a very smooth surface after the etching. The average roughness of the etched surface tends to be low at the higher temperatures. The etch rate behavior is discussed from the view points of the transport phenomena in the reactor and the chemical process at the substrate surface; their rate constants are obtained.