Patent ID: 8809986

Claim:
A semiconductor device comprising: a main element domain; and a sense element domain disposed adjacent to the main element domain; wherein each of the main element domain and the sense element domain comprises a first semiconductor layer, a second semiconductor layer directly laminated on the first semiconductor layer, a third semiconductor layer directly laminated on the second semiconductor layer, an insulating film and a trench gate electrode penetrating the third semiconductor layer and facing the third semiconductor layer via the insulating film, the first semiconductor layer is formed of a n or p type semiconductor, the second semiconductor layer is formed of the same type semiconductor as the first semiconductor layer, the third semiconductor layer is formed of the opposite type semiconductor to the first semiconductor layer, and an impurity concentration of the second semiconductor layer is lower than that of the first semiconductor layer, the first semiconductor layer is a continuous layer between the main element domain and the sense element domain, the second semiconductor layer is a continuous layer between the main element domain and the sense element domain, the third semiconductor layer is a continuous layer between the main element domain and the sense element domain via the trench gate electrode and the insulating film, wherein when the semiconductor device turns on, a channel is formed in each of the third semiconductor layers of the main element domain and the sense element domain due to the semiconductor in the third semiconductor layer near the insulating film being inverted to the same type as the first semiconductor layer, and current flows from the second semiconductor layer to the third semiconductor layer or from the third semiconductor layer to the second semiconductor layer, the main element domain includes more elements than the sense element domain, the elements being configured to apply the current through the channel when the semiconductor device turns on, and a thickness of the third semiconductor layer of the sense element domain is entirely smaller than that of the third semiconductor layer of the main element domain.