Silicon on insulator structure and method of making the same

A method of making a silicon on insulator (SOI) structure, comprising steps of:

• Step S1:
• providing a bonded structure, the bonded structure comprises the first substrate, the second substrate and the insulating buried layer, the insulating buried layer is positioned between the first substrate and the second substrate;
• Step S2:
• peeling off a layer of removing region of the first substrate from the bonded structure to obtain a first film;
• Step S3:
• at a first temperature, performing a first etching to etch the first film to remove a first thickness of the first film;
• and
• Step S4:
• at a second temperature, performing a second etching to etch the first film to planarize the first film and remove a second thickness of the first film, the first temperature being lower than the second temperature, the first thickness being greater than the second thickness, and a sum of the first thickness and the second thickness being a total etching thickness of the first film;
• wherein
• the first etching is performed with parameters of:
• etching temperature being 900° C. 1000° C., flow of the first carrier gas being 40 slm˜120 slm, and volume fraction of the first etching gas being lower than 1%;
• the second etching is performed with parameters of:
• etching temperature being higher than 1050° C., flow of the second carrier gas being 40 slm˜120 slm, volume fraction of the second etching gas being lower than 0.5%, and volume fraction of the second etching gas being lower than volume fraction of the first etching gas;
• and
• both of the first etching gas and the second etching gas comprise HCl gas.