(53f) Kinetics of Wet Thermal Oxidation of 6H Silicon Carbide

There has been increasing interest and demand for harsh environment sensors and electronics from government and industry in recent years, for example in propulsion and power instrumentation applications which require operation up to 600 oC to optimize fuel efficiency, emissions, and safety. SiC is well known for its combination of excellent mechanical, electrical, and chemical properties, including high yield strength, wide bandgap, high breakdown voltage, high thermal conductivity, resistance to oxidation and creep, chemical inertness to oxidation, and chemical resistance to alkaline and acidic solutions. These excellent properties make silicon carbide an ideal semiconductor material for high temperature, high power, and high voltage electronic devices. The advantage of SiC to form thermal oxide (SiO2) over other compound semiconductors has led to many SiC electronic devices such as power metal-oxide-semiconductor field-effect-transistors (MOSFET) analogous to the Si/SiO2 based microelectronic technology. Thermal oxidation of SiC is also an important process for insulation of individual electronic device and for large scale integrated circuits. Accurate prediction of thermal oxidation thickness for both p-type and n-type SiC with various doping concentrations motivates this study.

Wet thermal oxidation rate of SiC using H2 and O2 gas mixture is much faster than dry oxidation rate using just O2. The kinetics of wet thermal oxidation of 6H-SiC with epitaxial multilayers and both p-type and n-type doping and various doping concentrations are investigated. A modified Deal-Grove model is developed for the kinetics of wet oxidation of 6H-SiC. Experimental data indicate that the doping type and doping concentration significantly affect thermal oxidation rate. For short oxidation times where the chemical reaction rate is considered as the controlling process, the oxide thicknesses are measured for p type and n type doped SiC with various doping concentrations. For long oxidation times where the diffusion of oxidizing species through the oxide layer is considered as the limiting process, data from literature are used for the modified Deal-Grove model. The doping concentration dependent thermal oxidation rate is related to the doping induced crystalline defects. The results are very valuable for process simulation and development of wet thermal oxidation of SiC with specific doping type and dopant concentration.