Patent ID: 7982288
Filing Date: 2011-07-19
Classification: H01L

Abstract:
1. A semiconductor device, comprising: a substrate, comprising a high voltage circuit area, a medium voltage circuit area and a low voltage circuit area; a first well of a first conductivity type, disposed in the substrate; a high voltage device of a second conductivity type, disposed in the high voltage circuit area; a medium voltage device of the second conductivity type, disposed in the medium voltage circuit area; and a low voltage device of the second conductivity type, disposed in the low voltage circuit area, wherein a structure of the medium voltage device is the same as a structure of the high voltage device while the structure of the medium voltage device is different from a structure of the low voltage device; wherein the high voltage device, the medium voltage device and the low voltage device respectively comprise a first gate dielectric layer, a second gate dielectric layer and a third gate dielectric layer, and a thickness of the second gate dielectric layer is smaller than a thickness of the first gate dielectric layer; and wherein the high voltage device and the medium voltage device each comprise: a gate structure, disposed on the substrate; two source and drain regions of the second conductivity type, disposed in the substrate beside the gate structure; and at least one isolation structure disposed in the substrate between the gate structure thereof and one of the two source and drain regions thereof.