Preparation And Application Of Gel Polishing Tool For CVD Single Crystal Diamond

CVD single crystal diamond is the most promising candidate material for next-generation power devices.However,the large-scale application of diamond devices is still facing many challenges,especially the preparation of single crystal diamond substrates with large size,no dislocations,and low resistivity.Among them,precision polishing technology can enable diamond to obtain nano-level roughness surface and low subsurface damage,create conditions for diamond growth and epitaxy,and will play an important role in the process of preparing large-size high-quality diamond substrates.In view of the polishing needs of CVD single crystal diamond in the field of semiconductor materials and the properties of diamond polishing,the study envisages to prepare a new type of gel polishing tool and uses mixed abrasives(diamond abrasive and cerium oxide abrasive)to polish CVD single crystal at high speed to induce mechanochemical reaction between the abrasive and diamond,in order to achieve high efficiency,super precision and low damage polishing.Firstly,the study uses SG polishing tools as the basis to investigate the polishing conditions of CVD single crystal diamond by gel tools under low speed conditions.Secondly,a new polishing pad suitable for high-speed polishing environment was developed.Finally,this new type of polishing pad is used to polish CVD single crystal diamond at high speed.Meanwhile,the mechanochemical reaction and the material removal mechanism of diamond polishing are researched.The research results of this study are as follows:(1)A new type of polishing tool has been developed,which consists of gel,substrate,filler and abrasives.Polymer fiber pad and talc powder are used as the substrate and filler of the polishing pad,respectively.(2)It proves the feasibility of gel polishing tool to polish CVD single crystal diamond at high speed.Using a new type of polishing pad to polish CVD single crystal diamond at high speed,the surface roughness of the diamond is reduced from 100 nm to 5nm within 2 hours,which greatly shortens the polishing time compared to SG polishing tools.(3)A material removal mechanism for polishing a CVD single crystal diamond by a gel polishing tool at high rotation speed is proposed.The diamond abrasive particles rub the diamond surface at high speed,causing the diamond to be slightly broken,leaving grooves at the nanometer depth on the diamond surface,and mechanical stress induces the amorphization of diamond crystals.(4)The mechanochemical reaction of polishing CVD single crystal diamond with mixed abrasives(diamond abrasive and cerium oxide abrasive)at high speed is proposed.In the high-speed polishing environment,a large number of carbon atoms on the surface of the diamond are activated,further cerium oxide abrasives rub against the diamond surface,react with the groups(carbonyl groups,hydroxyl groups)on the surface of the diamond,and then take away the surface carbon atoms to achieve material removal.