Patent ID: 8377804

Claim:
A method for manufacturing semiconductor substrates, comprising the steps of: irradiating each of first to n-th (n≧2) single crystal semiconductor substrates with ions to form embrittlement layers in each of the first to n-th single crystal semiconductor substrates; bonding the first to n-th single crystal semiconductor substrates to first to n-th base substrates, with insulating layers provided on at least one of the single crystal semiconductor substrates and the base substrates and interposed between the first to n-th single crystal semiconductor substrates and the first to n-th base substrates, respectively; creating first to n-th single crystal semiconductor layers to the first to n-th base substrates, respectively by separation of the first to n-th single crystal semiconductor substrates, along the embrittlement layers by heat treatment; irradiating a plurality of regions in the first single crystal semiconductor layer having a median of thicknesses of n pieces of the single crystal semiconductor layers with laser beams, wherein each of the plurality of regions is irradiated with a laser beam having different energy density than other laser beams used for irradiation of other regions of the plurality of regions; detecting a plurality of peak values of detection signals of reflected microwaves of the first single crystal semiconductor layer irradiated with the laser beams, by a microwave photoconductivity decay method, wherein an energy density of a laser beam that corresponds to a maximum peak value of the detected signals is expressed by E 1 max ; and irradiating the second to n-th single crystal semiconductor layers with laser beams whose energy density E satisfies the following Formula 1: 0.90 E 1 max +3.9 σ≦E≦E 1 max −3.9σ, wherein σ satisfies the following Formula 2: σ=√{square root over ((2.87σ d ) 2 +σ e 2 )}, wherein σ d represents a standard deviation of thicknesses of n pieces of the single crystal semiconductor layers, and wherein σ e represents a standard deviation of the energy density of the laser beams for irradiation.