Preparation method of electronic-grade diamond

The invention provides a preparation method of electronic-grade diamond, the preparation method comprises the following steps: performing microwave plasma etching treatment on diamond seed crystals to obtain etched pretreated seed crystals; growing a single crystal diamond transition layer on the (100) surface of the etching pretreatment seed crystal through microwave plasma assisted CVD; and growing electronic-grade diamond on the surface of the monocrystal diamond transition layer through microwave plasma assisted CVD. According to the method provided by the invention, a step-by-step growth mode is adopted, the transition layer monocrystal diamond with a certain thickness is firstly grown, the monocrystal diamond transition layer can correct the defect of the diamond seed crystal substrate, and then the microwave plasma is adopted to assist CVD to grow the electronic grade diamond, and finally, the electronic-grade single crystal diamond material with the impurity content lower than 2 ppm is prepared. 本发明提供