A Novel Approach to Measuring Doping in SiC by Micro Spot Corona-Kelvin Method

Abstract

In this work we propose a novel approach to measuring doping concentration in SiC based on a micro-scale time-resolved corona-Kelvin technique. In this method corona charging of SiC surface into depletion is done within a micro size corona spot and a Kelvin-force micro-probe is used to measure surface voltage decay in the center of the spot. The voltage decay is due to charge decay due to surface diffusion producing analogy of voltage-charge scanning under the probe. We use 2D charge diffusion analysis to extract two parameters – 1) doping concentration in the SiC epitaxial layer and 2) diffusion coefficient of corona ions on the SiC surface. The micro-spot corona-Kelvin method demonstrated in this work shall prove of importance for testing of doping uniformity on micro scale and measurements on a small area in SiC production wafers.