Method for preparing silicon-on-insulator

A method for preparing silicon-on-insulator, comprising:

• providing an epitaxial substrate and a supporting substrate, wherein the epitaxial substrate is a p-type monocrystalline silicon epitaxial substrate;
• forming a first etching stop layer, a second etching stop layer, and a device layer from bottom to top on the epitaxial substrate by an epitaxial method, wherein the first etching stop layer is an intrinsic silicon layer, the second etching stop layer is a germanium-silicon alloy layer, and the device layer is a silicon device layer;
• forming an insulating layer, and bonding the device layer to the supporting substrate through the insulating layer;
• grinding the epitaxial substrate and keeping a part of the epitaxial substrate in reserve;
• performing a first etching by using a first etching solution to remove a remaining epitaxial substrate;
• performing a second etching by using a second etching solution to remove the first etching stop layer;
• performing a third etching by using a third etching solution to remove the second etching stop layer and forming a silicon-on-insulator structure;
• subjecting the silicon-on-insulator structure to a sacrificial oxidation treatment to remove a part of the device layer, and performing a thermal treatment to obtain a silicon-on-insulator film.