Non‐contact high precision alternative to Hg‐probe for dopant profiling in SiC

Abstract

AbstractThe silicon carbide industry has been expanding in the recent years, producing a search for SiC non‐contact electrical characterization methods capable of replacing the commonly used Hg‐probe technique. In this work we present doping metrology based on the corona‐Kelvin method, which was originally developed and used for silicon IC dielectric and interface characterization. The method employs corona discharge in air to deposit precise doses of charge on the SiC surface. The corresponding depletion voltage is then measured with a Kelvin probe enabling non‐contact determination of the static charge‐voltage and capacitance‐voltage characteristics. The approach incorporates three novel elements: 1. corona charging of SiC to high depletion voltage with constant surface potential method; 2. the derivative charge‐voltage measurements for d(1/C2)/dV analysis and doping profiling; 3. surface charge neutralization with appropriate SiC illumination for repeated measurements. We demonstrate excellent repeatability and accuracy of the novel approach for n and p‐type SiC doping measurements in a range from 1014cm‐3 to mid 1018cm‐3 and excellent correlation with results obtained with mercury‐probe C‐V. Using multi‐layer epitaxial SiC structures, we further demonstrate the effectiveness of novel non‐contact depth profiling. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)