A reverse conducting semiconductor device having a structure in which an IGBT element domain and a diode element domain coexist within a mutual semiconductor substrate is known. FIG. 1 exemplifies a border portion of a reverse conducting semiconductor device 20 having both an NPNP-type IGBT element domain and a diode element domain. Hereinbelow, the explanation will be given based on an example of the reverse conducting semiconductor device 20 having the NPNP-type IGBT element domain, however, the same applies to a reverse conducting semiconductor device having a reversed conductivity type and a PNPN-type IGBT element domain.
In the IGBT element domain 22 of the reverse conducting semiconductor device 20, a p-type body region 36, an n-type drift region 38 and a p-type collector region 44 are laminated. On a surface of the body region 36, an n+-type emitter region 30 is formed. In a region where the emitter region 30 is formed, a first trench gate electrode 26 penetrating the body region 36 which separates the emitter region 30 and the drift region 38 is formed.
Furthermore, in the diode element domain 24, the p-type body region 36, the n-type drift region 38 and an n-type drift contact region 40 are laminated. The body region 36 and the drift region 38 of the diode element domain 24 are composed by shared regions of the body region 36 and the drift region 38 of the IGBT element domain 22. On the surface of the body region 36, an n+-type first body contact region 35 and a p+-type second body contact region 34 are formed. In a region where the first body contact region 35 is formed, a second trench gate electrode 46 penetrating the body region 36 which separates the first body contact region 35 and the drift region 38 is formed.
In the reverse conducting semiconductor device 20, in a case where a positive voltage is applied to the first trench gate electrode 26 while a positive voltage that is higher than that of the emitter region 30 is being applied to the collector region 44, a current flows from the collector region 44 to the emitter region 30. On the other hand, in a case where a positive voltage that is higher than that of the drift contact region 40 is applied to the second body contact region 34, a current flows from the second body contact region 34 to the drift contact region 40.
If e.g. an inverter circuit is composed by using the reverse conducting semiconductor device, there is no need to separately prepare a semiconductor element that functions as an IGBT and a semiconductor element that functions as a diode.
In the above, the example of the NPNP-type IGBT element domain has been explained. In such a case, the second body contact region 34 and the body region 36 becomes an anode, and the drift region 38 and the drift contact region 40 becomes a cathode. In a case of using the PNPN-type IGBT element, the second body contact region 34 and the body region 36 becomes the cathode, and the drift region 38 and the drift contact region 40 becomes the anode.
The reverse conducting semiconductor device in which the IGBT element domain and the diode element domain coexist within the mutual semiconductor substrate is disclosed in Japanese Patent Application Publication Nos. 2000-245137 and 2003-60208.