High Temperature Model And The Key Processes Of SiC MOSFET

As one of the so-called third generation semiconductor materials- Silicon Carbide, has a very good electrical and thermal property. These properties make SiC a preferred semiconductor for preparation of devices in the environments of high temperature, high frequency, and high power. In this thesis, our studies concentrated on the high temperature characteristic of SiC MOSFET, and the key process technology—ohmic contact has been investigated under the fabrication ability of our own.The relationship between threshold voltage and temperature are discussed by the study of carrier freeze-out effect, the channel mobility and the intrinsic concentration. And then, the temperature dependency of Source/Drain series resistance and SiC pn diode's reverse leakage current are presented.An analytical model, which accurately reproduces the I-V characteristics of SiC MOSFET in a wide temperature range is reported. The effects of temperature on the threshold voltage, channel mobility, the body leakage current, and the drain/source sheet resistances are studied as several compensating current elements. It includes the Gauss model of interface traps and the Poole-Frenkel effect in the body. The simulation results showed that the large variation of the threshold voltage results in a huge change in the drain currents, and the percent of body leakage current getting bigger with the increase of temperature due to the Poole-Frenkel effct caused by several traps, it gradually plays a major role in the total current.Two different methods have been used to fabricate SiC ohmic contact with Ti/Ni/Au and Ti/Pt/Au respectively. With the testing TLM structures, low specific contact resistances( ～ 10^-6 Ω·cm²)have been achieved and secondary ion mass spectrometry (SIMS) is employed to examine the metal-semiconductor interface reaction.