工艺参数对高功率MPCVD金刚石膜择优取向的影响研究

Effects of Process Parameters on the Preferred Orientation of Diamond Films Deposited by MPCVD

使用自行研制的椭球谐振腔式MPCVD装置,以H2-CH4为气源、沉积功率8 kW条件下,在不同CH4浓度、沉积温度和气体流量工艺条件下制备了大面积金刚石膜。使用X射线衍射仪对金刚石膜的择优取向的变化规律进行了研究。实验结果表明,高功率条件下工艺参数对金刚石膜的择优取向有不同程度的影响。在CH4浓度由0.5%上升到1.0%时,金刚石膜的择优取向由(220)转变为(111),由1.0%上升到2.5%时,则由(111)转变为(220)以及(311);在700～1050℃温度范围内,随着沉积温度的升高,金刚石膜(111)择优取向生长的倾向增高,当沉积温度高于1050℃时,金刚石膜改变了原先的以(111)择优取向生长的趋势,变为了以(100)择优取向生长;在气体流速为200～1000 sccm范围内时,随气体流量的增加,金刚石膜(111)择优取向的倾向增加。当气体流量大于1000sccm时,金刚石膜(111)择优取向的倾向又稍有降低。

Polycrystalline diamond film was grown by using H2-CH4 as the source gas in a newly developed ellipsoidal MPCVD reactor at an input microwave power of 8 kW, different methane concentration, deposition temperature and gas flow. The selectivity of crystal orientation was examined by using X-ray diffraction. The results show that the change of process parameters have a significant effect on preferred orientation of diamond films at high microwave power. When CH4 concentration increased from 0.5% to 1%, the preferred （200） growth orientation of the diamond films was changed to （111 ） orientation. However, the （ 111 ） orientation changed to （220） and （311 ） preferred orientations when the CH4 concentration increased from 1.0% to 2.5%. In the temperature range of 700-1050 ℃, （ 111 ） preferred growth orientation was enhanced as the temperature increasing. At 1050 ℃ and above, the diamond films grow at （100） preferred orientation instead of （111） preferred orientation. Moreover, the preferred （ 111 ） orientation of the diamond films was enhanced as the gas flow rate increases from 200 to1000 sccm, whereas it showed a decrease when the gas flow increased to 1000 sccm and above.