Patent ID: 7332399
Filing Date: 2008-02-19
Classification: H01L

Abstract:
1. A method for manufacturing a semiconductor substrate comprising: forming a first semiconductor layer that has a first etching rate on a semiconductor substrate; forming a second semiconductor layer having a second etching rate smaller than the first etching rate of the first semiconductor layer; forming a first groove that penetrates the first semiconductor layer and the second semiconductor layer, such that at least a part of the semiconductor substrate is exposed in the first groove; forming a semiconductor supporting portion formed on side walls of the first groove, the semiconductor supporting portion having a third etching rate smaller than the first etching rate of the first semiconductor layer; forming a second groove in which at least a part of the first semiconductor layer is exposed such that at least a part of the semiconductor supporting portion remains; removing the first semiconductor layer by etching the first semiconductor layer through the second groove; and forming a first dielectric film and a second dielectric film by thermally oxidizing the semiconductor substrate, the second semiconductor layer and the semiconductor supporting portion, the forming of the first dielectric film and the second dielectric film being carried out such that the first dielectric film is disposed between a back surface side of the second semiconductor layer and the semiconductor substrate while the second dielectric film formed on side walls of the first groove and the second groove.