Patent ID: 8013381
Filing Date: 2011-09-06
Classification: H01L

Abstract:
1. A semiconductor device, comprising: a semiconductor substrate of a first conductivity type; a first high-voltage insulated-gate field effect transistor formed on a principal surface of the semiconductor substrate; a second high-voltage insulated-gate field effect transistor formed on the principal surface of the semiconductor substrate; a third high-voltage insulated-gate field effect transistor formed on the principal surface of the semiconductor substrate; a first device isolation insulating film that is formed in the semiconductor substrate and isolates the first high-voltage insulated-gate field effect transistor and the second high-voltage insulated-gate field effect transistor from each other; a second device isolation insulating film that is formed in the semiconductor substrate and isolates the first high-voltage insulated-gate field effect transistor and the third high-voltage insulated-gate field effect transistor from each other; a first impurity diffusion layer of the first conductivity type that is formed below the first device isolation insulating film; and a second impurity diffusion layer of the first conductivity type that is formed below the second device isolation insulating film, wherein the gate electrode of the first high-voltage insulated-gate field effect transistor and the gate electrode of the second high-voltage insulated-gate field effect transistor are connected to each other over the first device isolation insulating film, and the impurity concentration of the second impurity diffusion layer is higher than the impurity concentration of the first impurity diffusion layer.