Preparation process of silicon substrate with insulating buried layer

The invention relates to a preparation process of a silicon substrate with an insulating buried layer. The preparation process comprises the following steps: preparing a polished silicon wafer as a device layer silicon substrate and an oxidized silicon wafer as a supporting silicon substrate, respectively carrying out plasma surface activation treatment, carrying out low-temperature annealing after normal-temperature bonding, thinning to a target thickness by adopting mechanical grinding, then carrying out CMP treatment, and finally, carrying out high-temperature argon annealing treatment on the polished bonding wafer. The preparation process has the advantages that on the premise that the high-temperature thermal budget is not greatly increased by bonding the silicon wafer, the bonding strength is enhanced through a two-step annealing mode of low-temperature annealing and high-temperature argon annealing, and meanwhile, the extremely low primary particle defect density in the silicon substrate with the insul