Semiconductor device
A semiconductor device includes a semiconductor substrate, a contact region, a carrier suppression region and an electrode. The semiconductor substrate is shared by an insulated gate bipolar transistor (IGBT) region with an IGBT element and a freewheeling diode (FWD) region with an FWD element. The carrier suppression region is exposed from a surface of the semiconductor substrate in the IGBT region, and has a lower impurity concentration than the contact region. The carrier suppression region has a Schottky barrier junction with the electrode.
1. A semiconductor device comprising:
a semiconductor substrate shared by an insulated gate bipolar transistor (IGBT) region with an IGBT element and a freewheeling diode (FWD) region with an FWD element, the semiconductor substrate including
a drift layer of a first conductivity type,
a base layer of a second conductivity type disposed on the drift layer,
a collector layer of the second conductivity type disposed at an opposite side of the drift layer from the base layer in the IGBT region, and
a cathode layer of the first conductivity type disposed at the opposite side of the drift layer from the base layer in the FWD region;
a plurality of trenches penetrating the base layer to reach the drift layer, each of the trenches having a lengthwise direction and extending in the lengthwise direction;
a gate insulation film disposed at a wall surface of each of the trenches in the IGBT region;
a gate electrode disposed on the gate insulation film;
an emitter region of the first conductivity type as a surface layer portion of the base layer that is in contact with each of the trenches in the IGBT region, the emitter region having a higher impurity concentration than the drift layer;
a contact region of the second conductivity type disposed at the surface layer portion of the base layer in the IGBT region, the contact region having a higher impurity concentration than the base layer;
a first electrode disposed at a first surface of the semiconductor substrate at a side closer to the base layer, the first electrode electrically connected to the base layer and the emitter region;
a second electrode disposed at a second surface of the semiconductor substrate at a side closer to the collector layer and the cathode layer, the second electrode electrically connected to the collector layer and the cathode layer; and
a carrier suppression region of the second conductivity type exposed from the first surface of the substrate in the IGBT region, the carrier suppression region having a lower impurity concentration than the contact region,
wherein the first electrode has a Schottky barrier junction with the carrier suppression region.
2. The semiconductor device according to claim 1 ,
wherein the base layer is divided into a lower base layer and an upper base layer by a carrier storage layer in the IGBT region,
wherein the lower base layer is at a side closer to the drift layer, and the upper base layer is at a side closer to the first surface of the semiconductor substrate,
wherein the carrier storage layer has a higher impurity concentration than the drift layer, and
wherein an impurity concentration of the lower base layer is different from an impurity concentration of the upper base layer.
3. The semiconductor device according to claim 1 ,
wherein the emitter region and the contact region are alternately disposed along the lengthwise direction of each of the trenches in the IGBT region.
4. The semiconductor device according to claim 3 ,
wherein the carrier suppression region is disposed inside the contact region, and is separated from the emitter region.
5. The semiconductor device according to claim 4 ,
wherein a ratio of an area of the contact region to an area of the carrier suppression region is equal to or smaller than 1 to 2.