Study On Fabrication And Characterization Of MESFET And Resonator Based On SiC

Silicon carbide(SiC) is recently receiving increased attention due to its unique electrical and thermal properties. It has been regarded as the most appropriate semiconductor material for high-power, high-frequency, high-temperature, and radiation hard microelectronic devices. The fabrication and characterization of MESFET and resonator, as well as device processes, such as expitaxial growth of SiC on SiO₂/Si substrate, metallization and ICP etching, were investigated. The main work are summarized as follows:1.First, the characteristics of SiC films grown on SiO₂/Si substrate was studied elaborately. XRD spectrums show that the as-grown film is polycrystalline 3C-SiC, which is confirmed by XPS testing further. By SEM images three-layer structure can be seen clearly with no voids formed at the interface between 3C-SiC and SiO₂. Thickness of 3C-SiC at the bottom of the trench is smaller than on the mesa. Secondly, the characteristics of ohmic contact between SiC an Ni was investigated using transmission line model (TLM). Ni layer was deposited on both 3C-SiC and 4H-SiC substrate. The experimental results of the two substrates are discussed and compared. The results show that specific contact resistance (ρ_c) of annealed Ni films on 3C-SiC and 4H-SiC are 10^-2Ω·cm² and 10^-3Ω·cm², respectively. Under the same annealing condition, ρ_c of Ni/4H-SiC contact is smaller than that of Ni/3C-SiC.Finally, SiC ICP etching was investigated using different etch gases and variant experimental parameters, and optimum etching conditions were obtained.2.Based on above fundamental experiments, MESFET and resonator were fabricated. Because the opposite area between movable and stationary combs is smaller due to the gravity of shuttle, the sensitivity of resonator is lower, or because of mismatch of the testing circuit network, no results are attained. The characteristics of MESFET shows that the maximum saturation drain current of 4H-SiC MESFET is 17mA under room temperature, the turn-on voltage is 4V. For interdigitated gate MESFET fabricated using imported materials, the saturation drain current is about 20mA at a drain voltage of 50V, so the power density is 3.3W/mm. To improve device characteristics, processes conditions need to be meliorated.In this thesis, SiC processes were systematically studied and the characteristicsof devices was tested preliminarily. These results lay a good foundation for further fabricating SiC-based devices used for high-power, high-frequency, high-temperature.