SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING SAME

摘要

Opposite direction in-plane stresses are applied to an upper portion and a lower portion of active regions (23a, 23b) of a silicon layer (23) of an SOI substrate (1), and thus opposite direction distortions are introduced to the upper portion and the lower portion of crystalline lattice. In such case, a distortion in a direction required for improving mobility of transistor structures (10a, 10b) is introduced to the upper portion, and a distortion in a direction opposite to such direction is introduced to the lower portion, respectively. In such manner, the desired distortions are stably given locally to the regions close to the surface of a thin active region such as the silicon layer (23) of the SOI substrate (1), and an extremely high mobility can be easily and surely obtained.