一种提高MPCVD法制备金刚石膜均匀性的方法

采用自制的1 kW石英钟罩式微波等离子体化学气相沉积装置,以氢气和甲烷作为气源在镜面抛光的(100)面单晶硅片上沉积了金刚石薄膜。实验共制得两个样品,其中一个样品在制备的过程中加装了难熔的金属钽环,利用等离子体易吸附于金属钽环表面的特性,缩小了硅片中间与边缘等离子体密度差异,另外一个样品没有加装难熔的金属钽环。利用激光拉曼光谱仪和扫描电子显微镜(SEM)对制备的样品进行了表征,发现没有加装金属钽环的样品中间位置沉积的金刚石膜质量明显高于边缘位置沉积的金刚石膜,中间位置、离中间5 mm位置、边缘位置沉积膜层的厚度差别很大;加装了金属钽环的样品中间位置与边缘位置沉积的金刚石膜质量差不多,中间位置、离中间5 mm位置、边缘位置沉积膜层的厚度差别不大,上述结果证明金属钽环的加入是一种提高MPCVD法制备金刚石膜均匀性的方法。

A Method of Improving the Uniformity of Diamond Films Prepared by MPCVD

Diamond thin films were deposited onto mirror-polished （100） facets single-crystal silicon wafers using a gas mixture of hydrogen and methane by a home-made 1 kW quartz bell jar microwave plasma chemical vapor deposition （MPCVD） apparatus. Two samples were prepared by the experiment. During the preparation process, a tantalum ring of refractory metal was added into one of the samples to narrow the plasma density differences between center and edge of the silicon wafer by the behavior that plasma is easily adsorbed on the surface of tantalum metal ring. Another sample had no tantalum ring addition. Samples were characterized by Raman spectroscopy and SEM. Results show that the quality of diamond films deposited on the center of the sample is significantly higher than that deposited on the edge of the sample without tantalum metal ring addition. There are big differences among film thicknesses of substrate center,5mm away from substrate centre and substrate edge of the sample without tantalum metal ring addition. The quality of diamond films deposited on the center of the sample is almost the same as diamond films deposited on the edge of the sample with tantalum ring addition. There are little differences among film thicknesses of the three different areas of the sample with tantalum ring addition. The results above have proved that addition of tantalum metal ring is a method to improve the uniformity of diamond films prepared by MPCVD.