Patent ID: 7622777

Claim:
A semiconductor device comprising: a first MIS transistor formed in a first region of a semiconductor substrate; a second MIS transistor formed in a second region of the semiconductor substrate; and a third MIS transistor formed in a third region of the semiconductor substrate, wherein the first MIS transistor includes a first gate insulating film formed on the first region, a first gate electrode formed on the first gate insulating film, a first impurity doped layer formed in part of the first region located at each side of the first gate electrode and a first threshold control layer formed in part of the first region located under the first gate electrode, wherein the second MIS transistor includes a second gate insulating film formed on the second region, a second gate electrode formed on the second gate insulating film, a second impurity doped layer formed in part of the second region located at each side of the second gate electrode and a second threshold control layer formed in part of the second region located under the second gate electrode, wherein the third MIS transistor includes a third gate insulating film formed on the third region, a third gate electrode formed on the third gate insulating film, a third impurity doped layer formed in part of the third region located at each side of the third gate electrode and a third threshold control layer formed in part of the third region located under the third gate electrode, wherein a thickness of the second gate insulating film is substantially the same as or smaller than a thickness of the first gate insulating film and is larger than a thickness of the third gate insulating film, wherein the second impurity doped layer has substantially the same impurity concentration profile as an impurity concentration profile of the third impurity doped layer and has a lower impurity concentration than an impurity concentration of the first impurity doped layer, and wherein the second threshold control layer has substantially the same impurity concentration profile as an impurity concentration profile of the first threshold control layer and has a lower impurity concentration than an impurity concentration of the third threshold control layer.