Numerical Simulation And Experimerntal Study Of A Novel Type High-power MPCVD Reactor For Diamond Films Deposition

With excellent physical, chemical and mechanical properties, high qualitydiamond films deposited by chemical vapor deposition (CVD) method arewidely applied in high-technology fields. Microwave plasma chemical vapordeposition (MPCVD) is a preferred technology to produce high-quality diamondfilms. However, due to its low deposition rate and high cost, application of highperformance materials deposited by MPCVD method is largely limited. Thoughthe deposition rate can be increased by raising pressure of the react gas, thedeposition area will be decreased. Therefore, in order to obtain a high depositionrate as well as a considerable deposition area, the power capacity of MPCVDdevice needs to be sharply improved. As present device suffer from the situationof low working power, the investigation of high power MPCVD reactor ischosen as the topic in this paper.Primarily, this paper expounded the development of high quality MPCVDdiamond films and MPCVD diamond reactor, and discussed the advantages anddisadvantages of different MPCVD reactors. Combined with the fundamental conditions needed for high power MPCVD diamond film device, a model namedTYUT was carried out, which contained the advantage of current devices. Then,the basic size of devices and its critical components were simulated andoptimized by simulation software, in accordance with the location, condition andstrength of electric field. Moreover, the possible factors resulting in themistuning of device were comprehensively analyzed, and the performance oftuning mechanism of this design was verified by simulating. Simulation resultsshowed that, there were many factors resulting in the mistuning of device, suchas the frequency deviation of microwave, the machining error of resonant cavityand the height variation of substrate, whereas the tuning mechanism designed inthis paper could be successfully achieved via tuning. Consequently, these resultslaid the foundation of the establishment of TYUT-MPCVD diamond filmdeposition reactor.On the basis of the optimized results by simulating, a TYUT-MPCVDreactor was established. This reactor not only contained higher microwavepower (>9kW), but also had an admirable tuning function through theexperimental measurements. Subsequently, the deposition experiments undertwo conditions with high power and with high pressure were respectivelyemployed in this reactor. The deposition rate and thickness inhomogeneity of theprepared diamond film with40mm diameter could be achieved at12μm/h andless than5%, while those of the65-mm-diameter diamond film were5.6μm/hand less than6%, respectively. Additionally, both the diamond films were obtained with high quality. These experimental results indicated that theTYUT-MPCVD reactor possessed excellent performance and lived up to thedesigning proposes. Meanwhile, it conformed the requirement under high powerdensity condition for the deposition of large area diamond films with highhomogeneity and fast deposition rate.