Study On ECR Hydrogen Plasma Treatment Of SiC Surface

Silicon carbide (SiC) is the third generation semiconductor material. It will be widely used on high-temperature, high-frequency and high-power electronic devices because of its wide bandgap, high physicochemical stability and high thermal conductivity. But there are surface states on the surface which make it difficult to get good omic contact or good SiO₂/SiC interface, which seriously affect the properties of the MOS devices. Many ways were used to ensure clean surfaces, including traditional wet cleaning, hydrogen annealing at high temperature and Hydrogen Plasma treatment and so on. The wet chemical treatment is relatively mature but leaves many ions groups on the surface. H₂ treatment in the atmospheric pressure can effectively terminate the surfaces which are against to the oxidation without introducing the contaminations, but this method needs the temperature at higher than 1000℃, which is bad for the Compatibility of the device. An atomically ordered, smooth surface was got by treating with rf hydrogen plasma, but the surface was (?)×(?) reconstruction.In this paper N-type 4H-SiC(0001) surfaces were cleaned by hydrogen plasma with electronic cyclotron resonance(ECR) plasma system, and the whole process was monitored by in-situ reflection high energy electron diffraction(RHEED).. We researched on the process conditions of hydrogen plasma, the impact of hydrogen plasma on surface chemical properties and the surface oxidation resistance, the impact on MOS capacitance devices and ohmic contact. The experiments show that form 200℃to 700℃were striated with distinct comparison which showed that the surface atoms were regularly organized and had good orientation of single crystal. No surface reconstruction was discovered after calculation. But if it was treated for too much time the surface atoms arrangement were destroyed which would convert to the Amorphous. The surface composition was analyzed using x-ray photoelectron spectroscopy (XPS). It is shown that the C/C-H contaminations were removed from the 4H-SiC surfaces and the surface oxides were reduced obviously. The surface oxidation resistance was enhanced. We made MOS capacitance devices and ohmic contact on SiC surfaces treated by hydrogen plasma, the analysis showed that the interface state intensity of MOS made on SiC surfaces treated by hydrogen plasma got to 6×10¹¹cm^-2ev^-1. It was obviously lower than on the SiC surfaces treated by wet cleaning. Ohmic contact could be got before annealing on SiC surfaces treated by hydrogen plasma which decreased the process difficulty. In this paper, N-type 4H-SiC(0001) surfaces were cleaned by hydrogen plasma with electronic cyclotron resonance(ECR) plasma system which can provide some processing parameters for further study on the mechanism of hydrogen passivation. Surface cleaning and surface passivation provide guarantee to get high-quality surface and SiC/SiO2 interface which makes it possible to get good ohmic contact and MOS devices.