US Patent 7821138 Semiconductor device with an improved operating property

The semiconductor comprises an n-channel transistor forming region and a p-channel transistor forming region, which are disposed while being sectioned by an element isolation region. The stress caused by contact plugs in the n-channel transistor forming region and the stress caused by contact plugs in the p-channel transistor forming region are made different from each other. With this, it enables to increase the drive current of both the n-channel transistor and p-channel transistor without changing the dimensions of the active region and the element isolation region.