Study Of The Growth Of Silicon Carbide By APCVD On Porous Silicon Substrate

Characterized by wide bandgap, silicon carbide is an excellent material with high breakage electric field, high thermal conductivity, high saturated electron mobility, which is considered as one of the most promising wide band gap semiconductors, and widely utilized in high temperature, high frequency and large power semiconductor devices. But the fabrication of single-crystal SiC costs too much and the process is very complicated, so the heteroexpitaxial growth of SiC on Si substrate become very popular in research. Due to the large lattice parameter mismatch(20%) and the large thermal expansion coefficient mismatch(8%), however, the heteroexpitaxial growth of SiC on Si substrate is difficult and still has problem to be studied.In this paper, the growth technology is presented for epitaxial silicon carbide films on porous silicon by atmosphere-pressure chemical vapor deposition(APCVD) process, that is, to fabricate porous silicon (PS) on the Si wafer by electrochemical etching method first in order to form a buffer layer, and then depositing the SiC films on this buffer layer. The porous silicon on the wafer was used to reduce the lattice parameter mismatch between Si wafer and SiC film, and then SiC film can be deposited on porous silicon without preparing a buffer layer on Si wafer in APCVD process.The chemical and physical process of atmosphere-pressure chemical vapor deposition SiC thin films is analyzed firstly. The structural properties of the films grown on porous silicon substrate are studied by X-ray diffraction(XRD), scanning electronic microscope(SEM) and EDS detector attachment to SEM. The effects of Si/C ratio of the source gas and growth temperature on the quality of thin films was studied in detail. It was observed that the size of particles in SiC film was increased with the decrease of Si/C ratio. The small Si/C ratio would accelerate the chemical process and lead to the formation of defeat and void on the surface of film, and the large Si/C ratio would lead to the different size and disorder of film particle. Only the proper Si/C ratio could obtain a SiC films that had a good single-crystalline orientation and a smooth surface. The single-crystalline orientation of the thin films meliorated with the increasing of growth temperature, the size of particles became large and the polycrystalline SiC films would turn to single crystal with the increasing of temperature.