MANUFACTURE OF SOI BOARD

PROBLEM TO BE SOLVED: To form a silicon device layer with a uniform thickness without a process for forming an etching stopping film separately by forming a silicon device layer by using an isolation film as an etching stopping film and etching a device substrate. SOLUTION: Buried oxide films 24A, 24B of a specified thickness are formed on a device silicon board 20 and a handling board 25. The device silicon board 20 and the handling board 25 are bonded to bring the buried oxide films 24A, 24B into contact with it. The device silicon board 20 is subjected to grinding and lapping to have a specified thickness. Successively, the field oxide film 23 is used for an etching stopping film and the remaining device silicon board 20 is polished chemically and mechanically to expose a surface of the field oxide film 23. Thereby, a silicon device layer 20A with a fixed thickness is formed.