Semiconductor device and manufacturing method thereof

摘要

A MISFET is provided with a segmented channel comprising regions in which the channel is inverted by a first gate voltage and regions in which the channel is inverted by a second gate voltage. The MISFET is formed in a semiconductor substrate having a first conductivity type and the first inversion region of the channel has a first impurity concentration determined by the surface concentration of the substrate. The second inversion region of the channel has a second impurity concentration determined by doping an impurity to the region selected by a photolithographic process. The first and second inversion regions may be divided into a plurality of plane shapes and the threshold voltage of the MISFET is set to a desired value in accordance with the plane area ratio of the first and second inversion regions.