| 摘要 |
PURPOSE:To enable the relaxation of impact ionization while the short channel effect is prevented by a method wherein, in the channel length direction, the impurity concentration is contrived to increase to the channel center and decrease toward the source and drain regions. CONSTITUTION:In the channel length direction of an MOS transistor, channel dope 50 has such a distribution that the impurity concentration is highest in the center C and decreases toward the source end A and the drain end B. The elongation of the drain side depletion layer is stopped in the nighborhood of the center C by controlling of the impurity concentration. In other words, the pich- off point of the channel is enabled to come close to the point C. This manner weakens the electric field at the drain end B and inhibits the generation of impact ionization. |
