| 摘要 |
PROBLEM TO BE SOLVED: To restrain disorder of structure in a hetero interface when heat treatment is performed, in a semiconductor device using a heterojunction containing mixed crystal semiconductor. SOLUTION: A lower Si cap layer 118 containing C, an i-Si1-yGey layer 119 (0<y<1), an i-Si cap layer 142, an SiO2 layer 117 and a gate electrode 116, are formed on a semiconductor substrate 101. Since C is contained in the lower Si cap layer 118, the movement, diffusion, segregation, etc., of Ge in the Si1-yGey layer 119 are restrained. As a result, disorder in the structure of an Si/Si1-yGey hetero interface 136 is restrained, and a clear and flat interface is maintained, so that characteristics such as conductivity of carriers in a channel along the hetero interface 136 is improved. That is, thermal budget of the semiconductor device, at thermal treatment, is improved. By imparting gradient to C concentration, diffusion of C into a gate insulating film is restrained, and deterioration in reliability and the like is prevented.
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