Research Of Large Scale Diamond Films Deposition Using A Novel MPCVD Apparatus

Chemical vapor deposition diamond film is one of some new materials due to its advanced physical and chemical property such as high hardness, thermal conductivity, electron mobility, chemical stability and so on. Chemical vapor deposition diamond attracts many attentions of researches because the property of CVD diamond and nature diamond is very similar. With the development of science and technology, the demands in various applications on the quality and scale of diamond films are increasing, therefore some deeper researches, improvement and optimizations on both apparatus and parameters are needed. Microwave plasma chemical vapor deposition, as an important and preferred method to deposit diamond films with high quality, attracts many researchers'attentions. In this study, a novel MPCVD apparatus which can be used to deposition large scale diamond films with high quality is used to research the diamond films deposition.Owing to having a multiply mode chamber in this novel MPCVD apparatus, two microwave modes that TM01 and TM02 which are main used in the experiments can be co-exist in the chamber to stimulate a large scale plasma ball. Meanwhile high energy density can be obtained, for the most proportion of microwave can be fed into the chamber via mode conversion antenna. The two characters of this novel MPCVD apparatus give the insurance of large scale CVD diamond films with high quality.Systematic researches on the parameters of CVD diamond films deposition are conducted from the aspect of substrate temperature, microwave power, deposition pressure, and carbon concentration in the apparatus. Analysis and discussion to parameters on the effects of diamond films are conducted on the basis of deposition mechanism in order to ascertain the range of choosing parameters provided that the requirements of the diamond films have been known. And the results of the researches are that the chances of second nucleation decreasing with the substrate temperature increasing; lower chamber pressure and higher microwave power can stimulate larger plasma ball, and enhancing microwave power can boost the deposition speed effectively; the CVD diamond films with crystalline form can be deposited through the adjustment of carbon concentration.The various parameters of the experiments are optimized on the grounds of that some interrelationships exist among all the parameters. Micron-grade diamond films with cylindrical growth and high flatness nano-crystalline diamond films are obtained under the optimized parameters and the speed of the traditional diamond and nano-crystalline diamond films are 1.3μm/h and 0.3μm/h respectively. The surface roughness and average grain size of the nano-crystalline diamond films are 21.8nm and 24.9nm.General rules of depositing diamond films in the novel MPCVD are gotten through the researches, which are the foundation for the deposition of large scale diamond films with high quality in some degree. Meanwhile, the analysis to the influence of every parameter to diamond films deposition can give theoretical direction to preparation high quality diamond films.