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

Abstract

The 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)

Depth Profiling of Ion-Implanted 4H–SiC Using Confocal Raman Spectroscopy

“…Currently, most characterization methods for the electrical properties above-mentioned need the preparation of special measurement structures or will destroy the sample in the process of obtaining the depth distribution of electrical parameters, while the operation procedures are laborious and time consuming: (a) the point contact current voltage (PCIV) [7] has several drawbacks including rather low sensitivity and the lack of required reference samples; (b) the electrochemical etching based depth profiling [8] was investigated but also exhibited insufficient accuracy and reliability. For doping profiles with lower maximum doping concentrations (<~5 × 10 17 cm −3 or even lower), the standard in industrial process control is based on well-established mercury capacitance voltage measurements, whereas basically similar but contactless methods seem to have arisen [9]. In addition, other techniques have been investigated and developed such as scanning spreading resistance microscopy (SSRM) or scanning capacitance microscopy (SCM), which, however, are time consuming and need elaborate sample preparation.…”

Recent Advancement in Charge and Photo-Assisted Non-Contact Electrical Characterization of SiC, GaN, and AlGaN/GaN HEMT

“…In wide bandgap semiconductors, the situation is different and the applications listed in Table 1 also include the bare wafers. Bare wafer dopant measurement and depth profiling are critical for SiC and GaN providing a non-contact alternative to the mercury probe MCV technique [4]. A large range, superior precision, and repeatability of dopant measurement has been achieved only recently with a novel constant surface potential corona-charging method [5,6] and photo-assisted corona charge removal [5,7].…”

Non-contact electrical characterization of GaN, SiC and AlGaN/GaN for device applications

“…A significant advantage compared to silicon is the excellent retention of corona charge on surfaces of wide-gap semiconductors. This expands the applications to bare wafers enabling the use of "corona-Kelvin" not only as a replacement for MOS characterization but also as a non-contact replacement for Schottky diode characterization including mercury probe C-V [2]. We demonstrate such capability using a novel constant surface potential corona charging method, and very accurate dopant density determination in epitaxial GaN and SiC [3].…”