Inductively coupled plasma etching of SiC in SF6/O2 and etch-induced surface chemical bonding modifications

Abstract

4H silicon carbide (SiC) substrates were dry etched in an inductively coupled plasma (ICP) system, using SF6/O2 gas mixtures. Etch rate and etch mechanisms have been investigated as a function of oxygen concentration in the gas mixture, ICP chuck power, work pressure, and flow rate. Corresponding to these etch conditions, surface information of the etched SiC has been obtained by x-ray photoelectron spectroscopy measurements. The fact that no obvious Si–Si and Si–F bonds were detected on the etched surface of SiC in all our etch experiments suggests efficient removal of Si atoms as volatile products during the processes. However, various kinds of C–F bonds have been detected on the etched SiC surface and the relative intensities of these bonds vary with the etch conditions. In addition, the nature of the incorporated F atoms on the etched surface also depends strongly on etch conditions, which was identified by the change of the relative ratio between semi-ionic and covalent carbon fluorine bonds. The electrical behavior for different bond structures on the etched SiC surface can be one of the basic reasons affecting related devices.