Ohmic contacts to single-crystalline 3C-SiC films for extreme-environment MEMS applications

Abstract

This paper describes the ohmic contacts to single-crystalline 3C-SiC thin films heteroepitaxially grown on Si (001) wafers. In this work, a TiW (titanium–tungsten) film was deposited as a contact material by RF magnetron sputter and annealed through the vacuum and rapid thermal anneal (RTA) process. Contact resistivity between the TiW film and the n-type 3C-SiC substrate was measured by the circular transmission line model (C-TLM) method. The contact phases and interface of the TiW/3C-SiC were evaluated with X-ray diffraction (XRD), scanning electron microscope (SEM) and Auger electron spectroscopy (AES) depth-profiles. The TiW film annealed at 1000°C for 45s with the RTA plays an important role in the formation of ohmic contact with the 3C-SiC film and the contact resistance is less than 4.62×10−4Ωcm2. Moreover, the inter-diffusion at the TiW/3C-SiC interface was not generated during, before and after annealing, and was kept in a stable state. Therefore, the ohmic contact formation technology of single-crystalline 3C-SiC films by using the TiW film is very suitable for high-temperature micro-electro-mechanical system (MEMS) applications.