Insulated-gate semiconductor device and method of manufacturing the same

1. An insulated-gate semiconductor device comprising:

a charge transport region of a first conductivity-type;

an injection control region of a second conductivity-type provided on the charge transport region;

a main charge supply region of the first conductivity-type selectively provided on the injection control region;

a dummy electrode buried, via a gate insulating film, in a dummy trench penetrating the main charge supply region and the injection control region to reach the charge transport region;

a gate electrode buried, via the gate insulating film, in a gate trench having at least one U-like shape in a planar pattern adjacent to the dummy trench to surround the dummy trench into the U-like shape, and having a depth identical to a depth of the dummy trench;

a gate surface wiring layer connected to the gate electrode at a bottom portion of the U-like shape; and

a connection land formed of a conductive layer connected to the dummy electrode, and selectively deposited on an opening side of the U-like shape.

2. The insulated-gate semiconductor device of claim 1 , wherein the dummy trench and the gate trench have stripes extending parallel to each other and having a continuous arrangement in a direction perpendicular to the extending direction of the stripes.

3. The insulated-gate semiconductor device of claim 2 , wherein:

two sets of the dummy trench and the gate trench having the continuous arrangement in the direction perpendicular to the extending direction are provided in rows such that the gate surface wiring layer having a stripe-shape extending parallel to the perpendicular direction is interposed between the two rows; and

ends of the gate trench in the respective rows are connected to each other in the extending direction.

4. The insulated-gate semiconductor device of claim 1 , wherein the gate trench has a plurality of U-like shapes alternately inverted and connected to each other in the planar pattern, and is delineated between a plurality of dummy trenches so as to have a meandering line surrounding the dummy trenches into the U-like shapes.

5. The insulated-gate semiconductor device of claim 1 , wherein the dummy trench has an O-like or I-like shape.

6. A method of manufacturing an insulated-gate semiconductor device, comprising:

forming an injection control region of a second conductivity-type on a charge transport region of a first conductivity-type;

forming a main charge supply region of the first conductivity-type on the injection control region;

digging a dummy trench so as to penetrate the main charge supply region and the injection control region to reach the charge transport region, and digging a gate trench so as to have a U-like shape in a planar pattern adjacent to the dummy trench to surround the dummy trench into the U-like shape;

burying a conductive film in the dummy trench via a gate insulating film to serve as a dummy electrode, and burying a conductive film in the gate trench via the gate insulating film to serve as a gate electrode;

forming a projection for testing connected to the dummy electrode via an opening of the U-like shape, and forming a wiring layer for testing connected to the projection for testing; and

testing an insulating property of the gate insulating film in the dummy trench by applying a voltage between the wiring layer for testing and a bottom surface of the charge transport region.

7. The method of claim 6 , further comprising, after testing the insulating property, forming a gate surface wiring layer covering the wiring layer for testing and connected to the gate electrode, and separating the wiring layer for testing and the projection for testing.

8. The method of claim 6 , wherein the dummy trench and the gate trench have stripes extending parallel to each other and having a continuous arrangement in a direction perpendicular to the extending direction of the stripes.

9. The method of claim 8 , wherein:

two sets of the dummy trench and the gate trench having the continuous arrangement in the direction perpendicular to the extending direction are provided in rows such that the gate surface wiring layer having a stripe-shape extending parallel to the perpendicular direction is interposed between the two rows; and

ends of the gate trench in the respective rows are connected to each other in the extending direction.

10. The method of claim 6 , wherein the gate trench has a plurality of U-like shapes alternately inverted and connected to each other in the planar pattern, and is delineated between a plurality of dummy trenches so as to have a meandering line surrounding the dummy trenches into the U-like shapes.

11. The method of claim 6 , wherein the dummy trench has an O-like or I-like shape.