US-12628363-B2 - Reverse conducting insulated gate bipolar transistor with specific impurity concentrations

Abstract

A semiconductor device includes a semiconductor part, first and second electrodes and a control electrode. The semiconductor part is provided between the first and second electrodes. The control electrode is provided between the semiconductor part and the second electrode. The semiconductor part includes first, third and fifth layers of a first conductivity type, and second, fourth, sixth and seventh layers of a second conductivity type. The second layer is provided between the first layer and the second electrode. The third layer is provided between the second layer and the second electrode. The fourth and fifth layers are provided between the first layer and the first electrode. The sixth layer surrounds the second and third layers. The seventh layer is provided between the first layer and the first electrode. The seventh layer surrounds the fourth and fifth layers and is apart from the fourth and fifth layers.

Inventors

• Ryohei GEJO

Assignees

• KABUSHIKI KAISHA TOSHIBA
• TOSHIBA ELECTRONIC DEVICES & STORAGE CORPORATION

Dates

Publication Date

20260512

Application Date

20220719

Priority Date

20220107

Claims (20)

1. 1 . A semiconductor device, comprising: a semiconductor part including an active region, and a termination region, the termination region surrounding the active region; a first electrode provided on a back surface of the semiconductor part; a second electrode provided on a front surface of the semiconductor part, the front surface being at a side opposite to the back surface; and a control electrode provided between the semiconductor part and the second electrode, the semiconductor part including first to eighth layers, the first, third, fifth and eighth layers being of a first conductivity type, the second, fourth, sixth and seventh layers being of a second conductivity type, the first layer being provided between the first electrode and the second electrode, the second layer being provided between the first layer and the second electrode in the active region, the third layer being provided between the second layer and the second electrode, the fourth and fifth layers being provided between the first layer and the first electrode in the active region, the fourth and fifth layers being arranged along the first electrode in a first direction, the sixth layer being provided in the termination region and surrounding the second and third layers at the front side of the semiconductor part, the seventh layer being provided between the first layer and the first electrode in the termination region, the seventh layer surrounding the fourth and fifth layers and being apart from the fourth and fifth layers, a distance from the active region to an outer edge of the seventh layer in the first direction being less than a distance from the active region to an outer edge of the sixth layer in the first direction, the eighth layer being provided between the first layer and the fourth layer, between the first layer and the fifth layer, and between the first layer and the seventh layer, wherein the eighth layer has a first-conductivity-type impurity concentration greater than a first-conductivity-type impurity concentration of the first layer, and the eighth layer extends entirely between the fourth layer and the seventh layer in a second direction perpendicular to the first direction and entirely between the fifth layer and the seventh layer in the second direction, while being in contact with the first electrode.
2. 2 . The device according to claim 1 , wherein the fourth layer, the fifth layer, and the seventh layer contact the first electrode.
3. 3 . The device according to claim 1 , wherein the fifth layer has a first-conductivity-type impurity concentration greater than the first-conductivity-type impurity concentration of the eighth layer.
4. 4 . The device according to claim 1 , wherein a distance from the fourth layer to the seventh layer in a first direction parallel to the back surface of the semiconductor part is greater than a width in the first direction of the seventh layer.
5. 5 . The device according to claim 4 , wherein the fourth layer has a minimum width in the first direction, the minimum width of the fourth layer is greater than the width in the first direction of the seventh layer.
6. 6 . The device according to claim 1 , wherein the semiconductor part includes a trench extending from the front surface into the first layer, the control electrode is provided inside the trench, the control electrode being electrically insulated from the semiconductor part by a first insulating film and electrically insulated from the second electrode by a second insulating film, the first layer and the second layer face the control electrode via the first insulating film, and the third layer contacts the first insulating film between the second layer and the second electrode.
7. 7 . The device according to claim 6 , wherein the sixth layer surrounds the control electrode.
8. 8 . The device according to claim 1 , wherein the semiconductor part further includes an eleventh layer provided in the active region, the eleventh layer being provided between the second layer and the second electrode, the eleventh layer being of the second conductivity type, the eleventh layer having a second-conductivity-type impurity concentration greater than a second-conductivity-type impurity concentration of the second layer, and the third layer and the eleventh layer are arranged on the second layer and contact the second electrode.
9. 9 . The device according to claim 1 , wherein the fourth layer and the fifth layer are repeatedly arranged in a direction parallel to the back surface, and a distance between the fourth layer closest to the termination region and the termination region in the direction parallel to the back surface is shorter than a distance between the fifth layer closest to the termination region and the termination region in the direction parallel to the back surface.
10. 10 . A semiconductor device, comprising: a semiconductor part including an active region, and a termination region, the termination region surrounding the active region; a first electrode provided on a back surface of the semiconductor part; a second electrode provided on a front surface of the semiconductor part, the front surface being at a side opposite to the back surface; and a control electrode provided between the semiconductor part and the second electrode, the semiconductor part including first to ninth layers, the first, third, fifth and eighth layers being of a first conductivity type, the second, fourth, sixth, seventh and ninth layers being of a second conductivity type, the first layer being provided between the first electrode and the second electrode, the second layer being provided between the first layer and the second electrode in the active region, the third layer being provided between the second layer and the second electrode, the fourth and fifth layers being provided between the first layer and the first electrode in the active region, the fourth and fifth layers being arranged along the first electrode in a first direction, the sixth layer being provided in the termination region and surrounding the second and third layers at the front side of the semiconductor part, the seventh layer being provided between the first layer and the first electrode in the termination region, the seventh layer surrounding the fourth and fifth layers and being apart from the fourth and fifth layers, a distance from the active region to an outer edge of the seventh layer in the first direction being less than a distance from the active region to an outer edge of the sixth layer in the first direction, the eighth layer being provided in an outer periphery of the seventh layer and physically in contact with the first electrode in the termination region, the ninth layer being provided between the fourth layer and the seventh layer and between the fifth layer and the seventh layer along an inner periphery of the seventh layer, wherein the ninth layer is of the second conductivity type, the ninth layer has a second-conductivity-type impurity concentration smaller than a second-conductivity-type impurity concentration of the fourth layer and a second-conductivity-type impurity concentration of the seventh layer, and the seventh layer is provided between the eighth layer and the ninth layer in the first direction while being in direct contact with the eighth layer and the ninth layer.
11. 11 . The device according to claim 10 , wherein the ninth layer contacts the first electrode.
12. 12 . The device according to claim 10 , wherein the semiconductor part further includes a tenth layer provided between the first layer and the first electrode, the seventh layer is provided between the active region and the tenth layer, and the tenth layer has a second-conductivity-type impurity concentration smaller than a second-conductivity-type impurity concentration of the fourth layer and a second-conductivity-type impurity concentration of the seventh layer.
13. 13 . The device according to claim 12 , wherein the tenth layer contacts the first electrode.
14. 14 . The device according to claim 10 , wherein the fourth layer and the fifth layer are repeatedly arranged in a direction parallel to the back surface, and a distance between the fourth layer closest to the termination region and the termination region in the direction parallel to the back surface is shorter than a distance between the fifth layer closest to the termination region and the termination region in the direction parallel to the back surface.
15. 15 . A semiconductor device, comprising: a semiconductor part including an active region, and a termination region, the termination region surrounding the active region; a first electrode provided on a back surface of the semiconductor part; a second electrode provided on a front surface of the semiconductor part, the front surface being at a side opposite to the back surface; and a control electrode provided between the semiconductor part and the second electrode, the semiconductor part including first to seventh layers, the first, third and fifth layers being of a first conductivity type, the second, fourth, sixth and seventh layers being of a second conductivity type, the first layer being provided between the first electrode and the second electrode, the second layer being provided between the first layer and the second electrode, the third layer being provided between the second layer and the second electrode, the fourth and fifth layers being provided between the first layer and the first electrode, the fourth and fifth layers being arranged along the first electrode in a first direction, the sixth layer being provided in the termination region and surrounding the second and third layers at the front side of the semiconductor part, the seventh layer being provided between the first layer and the first electrode in the termination region, the seventh layer surrounding the fourth and fifth layers and being apart from the fourth and fifth layers, a distance from the active region to an outer edge of the seventh layer in the first direction being less than a distance from the active region to an outer edge of the sixth layer in the first direction, wherein the semiconductor part includes a trench extending from the front surface into the first layer, the control electrode is provided inside the trench and is electrically insulated from the semiconductor part by a first insulating film and is electrically insulated from the second electrode by a second insulating film, and the sixth layer is in direct contact with the first insulating film.
16. 16 . The device according to claim 15 , wherein the fourth layer, the fifth layer, and the seventh layer contact the first electrode.
17. 17 . The device according to claim 15 , wherein the semiconductor part further includes an eighth layer provided between the first layer and the fourth layer, between the first layer and the fifth layer, and between the first layer and the seventh layer, the eighth layer has a first-conductivity-type impurity concentration greater than a first-conductivity-type impurity concentration of the first layer, and the eighth layer extends between the fourth layer and the seventh layer and between the fifth layer and the seventh layer.
18. 18 . The device according to claim 15 , wherein the eighth layer contacts the first electrode.
19. 19 . The device according to claim 15 , wherein the fifth layer has a first-conductivity-type impurity concentration greater than the first-conductivity-type impurity concentration of the eighth layer.
20. 20 . The device according to claim 15 , wherein the fourth layer and the fifth layer are repeatedly arranged in a direction parallel to the back surface, and a distance between the fourth layer closest to the termination region and the termination region in the direction parallel to the back surface is shorter than a distance between the fifth layer closest to the termination region and the termination region in the direction parallel to the back surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-001747, filed on Jan. 7, 2022; the entire contents of which are incorporated herein by reference. FIELD Embodiments relate to a semiconductor device. BACKGROUND A power control semiconductor device is required to have large tolerance for overcurrent in the on-state. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing a semiconductor device according to an embodiment; FIGS. 2A and 2B are schematic plan views showing the semiconductor device according to the embodiment; FIG. 3 is a graph showing a characteristic of the semiconductor device according to the embodiment; FIGS. 4A and 4B are schematic views showing a semiconductor device according to a modification of the embodiment; and FIG. 5 is a schematic cross-sectional view showing a semiconductor device according to another modification of the embodiment. DETAILED DESCRIPTION According to one embodiment, a semiconductor device includes a semiconductor part, a first electrode, a second electrode and a control electrode. The semiconductor part includes an active region and a termination region, the termination region surrounding the active region. The first electrode is provided on a back surface of the semiconductor part. The second electrode is provided on a front surface of the semiconductor part, the front surface being at a side opposite to the back surface. The control electrode is provided between the semiconductor part and the second electrode. The semiconductor part includes first to seventh layers. The first, third and fifth layers are of a first conductivity type, and the second, fourth, sixth and seventh layers are of a second conductivity type. The first layer is provided between the first electrode and the second electrode. The second layer is provided between the first layer and the second electrode. The third layer is provided between the second layer and the second electrode. The fourth and fifth layers are provided between the first layer and the first electrode. The fourth and fifth layers are arranged along the first electrode. The sixth layer is provided in the termination region and surrounds the second and third layers at the front side of the semiconductor part. The seventh layer is provided in the termination region. The seventh layer is provided between the first layer and the first electrode. The seventh layer surrounds the fourth and fifth layers, and is apart from the fourth and fifth layers. A distance from the active region to an outer edge of the seventh layer is less than a distance from the active region to an outer edge of the sixth layer. Embodiments will now be described with reference to the drawings. The same portions inside the drawings are marked with the same numerals; a detailed description is omitted as appropriate; and the different portions are described. The drawings are schematic or conceptual; and the relationships between the thicknesses and widths of portions, the proportions of sizes between portions, etc., are not necessarily the same as the actual values thereof. The dimensions and/or the proportions may be illustrated differently between the drawings, even in the case where the same portion is illustrated. There are cases where the dispositions of the components are described using the directions of XYZ axes shown in the drawings. The X-axis, the Y-axis, and the Z-axis are orthogonal to each other. Hereinbelow, the directions of the X-axis, the Y-axis, and the Z-axis are described as an X-direction, a Y-direction, and a Z-direction. Also, there are cases where the Z-direction is described as upward and the direction opposite to the Z-direction is described as downward. FIG. 1 is a schematic cross-sectional view showing a semiconductor device 1 according to an embodiment. The semiconductor device 1 is a RCIGBT (Reverse Conducting Insulated Gate Bipolar Transistor). The semiconductor device 1 includes, for example, a semiconductor part 10, a collector electrode 20, an emitter electrode 30, and a gate electrode 40. The semiconductor part 10 is, for example, silicon. The collector electrode 20 (a first electrode) is provided on the back surface of the semiconductor part 10. The emitter electrode 30 (a second electrode) is provided on the front surface of the semiconductor part 10. The front surface is at the side opposite to the back surface. The gate electrode 40 (a control electrode) is provided between the semiconductor part 10 and the emitter electrode 30. The semiconductor part 10 includes multiple gate trenches GT provided in the front side. The gate electrodes 40 are provided inside the multiple gate trenches GT, respectively. The gate electrode 40 is electrically insulated from the semiconductor part 10 by a gate insulating film 43 (a first insulating film). Also, the gate electrode 40 is electrically insulated from the em