Preparation process of silicon substrate on power insulator

The invention relates to a preparation process of a silicon substrate on a power insulator. The preparation process comprises the following steps: preparing a silicon epitaxial wafer as a device layer silicon substrate and an oxidized silicon wafer as a supporting silicon substrate, performing plasma surface activation treatment, performing low-temperature annealing after normal-temperature bonding, and performing low-temperature annealing after adopting a mechanical grinding thinning mode, removing a silicon single crystal of the substrate by using two-step selective acid corrosion of fast corrosion and slow corrosion, carrying out CMP polishing treatment, then carrying out high-temperature oxidation thinning treatment, and finally removing silicon oxide grown by high-temperature oxidation through diluted hydrofluoric acid corrosion; enabling the low-temperature annealing temperature after bonding to not exceed 400 DEG C; and enabling the polishing removal amount of the bonding wafer to not exceed 1 micron a