Patent ID: 7825007

Claim:
A method for manufacturing an SOI substrate comprising: performing heat treatment in an oxidizing atmosphere containing halogen to form an oxide film on each surface of a first semiconductor substrate and a second semiconductor substrate; performing irradiation with ions including one or a plurality of atoms, which are different in mass, from each one surface side of the first semiconductor substrate and the second semiconductor substrate to form a separation layer having a porous structure in each region, a depth of which is close to an average depth at which the ions reach from the each surface of the first semiconductor substrate and the second semiconductor substrate; forming a blocking layer formed of a silicon nitride film or a silicon nitride oxide film over the oxide film on the each surface of the first semiconductor substrate and the second semiconductor substrate; forming a silicon oxide film over the blocking layer of each of the first semiconductor substrate and the second semiconductor substrate; generating a crack in the separation layer, performing a first heat treatment for separating each of the first semiconductor substrate and the second semiconductor substrate with the separation layer, and forming a first single-crystal semiconductor layer from the first semiconductor substrate and a second single-crystal semiconductor layer from the second semiconductor substrate with a certain distance over a glass substrate, in a state where the each surface of the first semiconductor substrate and the second semiconductor substrate are overlapped with the glass substrate to overlap with the silicon oxide film interposed therebetween; performing a second heat treatment on the glass substrate at a temperature of greater than or equal to a strain point of the glass substrate to shrink the glass substrate after separating each of the first semiconductor substrate and the second semiconductor substrate with the separation layer, wherein the first single-crystal semiconductor layer and the second single-crystal semiconductor layer are in contact with each other by performing the second heat treatment; and after performing the second heat treatment, irradiating the first single-crystal semiconductor layer and the second single-crystal semiconductor layer with laser light, thereby integrating the first single-crystal semiconductor layer and the second single-crystal semiconductor layer to form a third single-crystal semiconductor layer comprising the first single-crystal semiconductor layer and the second single-crystal semiconductor layer.