工艺参数对高功率MPCVD金刚石膜择优取向的影响研究

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.O;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.

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

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 to 1000 sccm,whereas it showed a decrease when the gas flow increased to 1000 sccm and above.