Cost-Effective Formation of Ti/Ni/Ti/Au Ohmic Contacts to n-type SiC Using SiO2 Encapsulation Layer during Phosphorous Implant Activation

Abstract

The purpose of this research is to develop a cost-effective formation of ohmic contacts to n-type SiC through ion implantation and activation. Although Nitrogen is commonly used as an n-type dopant, especially for in-situ doping during epitaxial growth, Phosphorus was chosen because of its higher solubility limit in SiC materials. Consequently, Phosphorus can achieve selective doping at much higher concentrations (above 1020 cm-3), which will be beneficial in regions such as source/drain and cathode where low contact resistance is needed. After ion implantation, the dopants must be thermally activated, and crystal damage must be recovered through annealing at high temperature between 1400~1700°C. During this stage, the material used as the cap layer will have a notable impact on the morphology and structure of the material. The proposed ohmic metal stacks and SiO2 encapsulation enable cost-effective formation of ohmic contacts to n-type SiC where complex fabrication equipment setup is unavailable.