Patent ID: 7524705

Claim:
A method for manufacturing a semiconductor substrate, comprising: forming a first semiconductor layer on a region of a semiconductor base; forming a second semiconductor layer having an etching rate smaller than an etching rate of the first semiconductor layer; forming a support member to support the second semiconductor layer on the semiconductor base so as to cover the second semiconductor layer; forming an opening face in the support member to expose an edge of the first semiconductor layer; etching the first semiconductor layer through the opening face so as to form a cavity between the second semiconductor layer and the semiconductor base; cleaning the cavity through the opening face in a condition to remove a residue formed during etching of the first semiconductor layer; and forming an insulating film in the cavity after the cleaning of the cavity, the first semiconductor layer being made of SiGe, a cleaning solution used for the cleaning of the cavity being an APM cleaning solution including an aqueous ammonia solution and a hydrogen peroxide solution, the cleaning of the cavity being carried out by a combination of a first cleaning step and a second cleaning step, the first cleaning step being carried out by using the APM cleaning solution, and the second cleaning step being carried out by using any one of an HPM cleaning solution, an FPM cleaning solution, a SPM cleaning solution and a DHF cleaning solution.