MOS type semiconductor device having an impurity diffusion layer with a nonuniform impurity concentration profile in a channel region

摘要

A semiconductor device of the invention is formed so that the impurity concentration of a semiconductor substrate under a source diffusion layer is lower than the impurity concentration on a source side of a p-type impurity layer. Therefore, in the semiconductor device of the invention, the junction capacitance of the p-n junction between the source and the substrate is smaller as compared with a conventional LDC structure. In general, the speed of a device is proportional to the product obtained by multiplying together a load capacitance and an inverse of a current value of the device. Accordingly, in the case of applying the present invention to a circuit such as a NAND type CMOS circuit in which a voltage is applied to a region between the source and the substrate, the speed of the device is not decreased. On the other hand, the power consumption of a device is proportional to the product obtained by multiplying together a load capacitance and the square of an applied voltage. Consequently, according to the present invention, a semiconductor device which can be operated at a low power consumption is realized.