本文为改善反向外延生长3C-SiC薄膜中残余应力的工艺优化方法,采用LPCVD技术,将甲烷和氢气按1∶10比例混合后与n-Si(111)衬底反应,制备3C-SiC薄膜。通过X射线衍射分析仪、激光拉曼光谱仪和场发射扫描电子显微镜进行测试和分析。在该方法中,反应恒温1200℃为最优温度,反应温度过高或过低都不利于3C-SiC薄膜生长; 在反应温度为1200℃时,为增加薄膜厚度而单纯增加反应时长,缺陷浓度也会相应地增加,从而薄膜结晶质量相应降低; 但在1250℃反应温度时,增加反应时长不仅会增加薄膜的厚度,而且也会缓减薄膜中残余应力,同时改善薄膜的结晶质量。另外研究结果还表明: 1250℃时经过一个恒温的等时退火工艺后,再降温的方式可进一步降低薄膜中本征残余应力,从而改善薄膜的结晶质量和晶格失配。

In order to improve the residual stress and optimize the process conditions of reverse epitaxial 3C-SiC thin films,the 3C-SiC film based on the n-Si(111)was prepared with the methane and hydrogen mixture at the ratio of 1∶10 using LPCVD technology.The 3C-SiC films were characterized by X ray diffraction,laser Raman spectroscopy and field emission scanning electron microscopy.The experimental results show that the optimum reaction temperature is 1200℃,and the reaction temperature either too high or too low is not conducive to grow 3C-SiC film.When the reaction temperature is 1200℃,the film thickness and the concentration of defects will increase correspondingly with the increasing reaction time,so that the crystalline quality of the film can be decreased accordingly.However,when the reaction temperature is 1250℃,increasing the reaction time will not only increase the thickness of the film,but also reduce the residual stress in the film,and improve the crystalline quality of the film.In addition,the results show that the process of constant temperature and constant time annealing can further reduce the intrinsic residual stress,improve the crystalline quality of the thin film and crystal lattice mismatch.