无支撑优质金刚石膜研制中的相关问题探讨

无支撑优质金刚石膜在微波真空器件和光学器件中的广泛应用,有赖于制备成本的下降和工艺的完善。结合微波等离子体化学气相沉积(MPCVD)金刚石膜的工艺研究结果,本文就沉积速率、晶面取向以及内应力的相关问题进行了初步探讨。对于给定的设备,沉积速率与多种因素有关,包括膜的质量、膜厚均匀性和有效沉积面积、以及形核的密度。在通常情况下,金刚石膜呈(111)择优取向,而样品位置下移5mm后,观察到(100)取向。对内应力的初步研究表明,CH4/H2比例较低(1.5)时,金刚石膜的内应力趋向于压应力,而(100)取向的出现则有助于使内应力降到最低。

Growth and Characterization of High QualityFreestanding Diamond Films

The high quality freestanding diamond films were grown by microwave plasma chemical vapor deposition(MPCVD) on n-type,heavily-doped silicon wafer substrate.The influencing growth factors,such as the deposition rate,plasma density,ratio of CH4/H2 flow rates,and gas temperature,were evaluated.The microstructures and stress distribution of the diamond films were characterized with X-ray diffraction,and scanning electron microscopy.The results show that the deposition rate and ratio of CH4/H2 flow rates strongly affect the film quality.For instance,the(111) preferred growth orientation was observed under normal growth conditions;and at a lower ratio of CH4/H2 flow rates of ~1.5,compression stress dominates.However,when the substrate was lowered by 5 mm,the(100) oriented grains were observed,which possibly reduces the intrinsic stress.