| 摘要 |
PURPOSE:To prevent characteristic deterioration called channel leakage by fluctuation of the threshold value voltage by a method wherein a MOS field effect transistor includes a gate region having a plurality of threshold value voltages and thereby the threshold value voltage of a channel region liable to receive stress is in advance adjusted and changed. CONSTITUTION:A MOS field effect transistor includes a gate region having a plurality of threshold value voltages shown by A and B. For instance, suppose that great stress is put on the region A. In this case, the threshold value voltage lowers caused by increased interface charge or the like the MOS field effect transistor. In this case, however, when the p-type substrate impurity density in this region A is if advance raised higher than the region B (possible by an ordinary channel doping method or the like) to raise the threshold value voltage, the portion of the lowered threshold value voltage due to stress can be compensated for. |
