An SiGe layer is grown on a silicon substrate. The SiGe layer or the
silicon substrate and SiGe layer are porosified by anodizing the SiGe
layer to form a strain induction porous layer or a porous silicon layer
and strain induction porous layer. An SiGe layer and strained silicon
layer are formed on the resultant structure. The SiGe layer in the
stacking growth step only needs to be on the uppermost surface of the
porous layer. For this reason, an SiGe layer with a low defect density
and high concentration can be formed. Since the SiGe layer on the strain
induction porous layer can achieve a low defect density without lattice
mismatching. Hence, a high-quality semiconductor substrate having a high
strained silicon layer can be obtained.