Study On SiC Surface Modification Technology

The hydrogen passivation is a technology that make hydrogen atoms passivate the surface dangling bonds. hydrogen passivation technology can yield the cleaning-flat semiconductor surface,which has good anti-oxidation Capability. It is benefit to make high performent MOS devices and ohmic contacts. However, because there are polar bonding on SiC surface, Tradditional wet hydrogen passivation technology is not fit for SiC. In the hydrogen annealing technology or RF hydrogen plasma cleaning technolgy, It needs 1000℃or 650℃high tempreture to decompose hydrogen molecula. It finds that the higher the temperature is, the lower the coverage is.The surfaces of SiC are cleaned by hydrogen with ECR-PEMOCVD and the best technological conditions are studied. The structure of SiC surfaces composition,the contamination removing and the resisting oxidation of SiC surface are studied. The effects of hydrogen plasma on the MOS devices and ohmic contact are studied.It finds that after cleaned by hydrogen plasma for 12 minutes at 200℃,the surface of SiC shows the best effect and it becomes bad with the time increases.when it is 18 minutes,the picture of SiC RHEED becomes blurry.It is because that the surface of SiC is destroied by hydrogen plasma as the time increases, when the temperature increases, the time reduces,At 300℃,it is 5 minutes that it got the best effect.At 400℃,it is 4 minutes that it got the best effect. at 500℃,it is 2 minutes that got the best effect. Although the time is reduced, the cleaning effect become bad as the temperature increases.It finds by RHEED that after cleaned by hydrogen plasma at 200℃for 12 minutes, the surface of SiC show (1×1) phase. It finds by XPS that there are the C/CH contaminations on SiC surface after the traditional RCA cleaning. After cleaned by hydrogen plasma for 12 minutes at 200℃,they disappears. The intensity of SiOx for the SiC surface cleaned by RCA is higher than by hydrogen plasma for 12 minutes at 200℃.We make MOS device on the SiC which cleaned by hydrogen plasma for 12 minutes at 200℃.It shows that the intensity of interface State for the SiC which is cleaned by hydrogen plasam is lower than that for the SiC cleaned by RCA.At the same time,it finds that after cleaning by hydrogen plasma, the ohmic contact can be got at low temperature.