US-20260129889-A1 - SEMICONDUCTOR DEVICE

Abstract

A semiconductor device includes a collector electrode, a collector-side element trench structure, a collector-side gate pad, and a collector-side terminal trench structure. A side surface of the semiconductor substrate and the collector electrode surround the collector-side gate pad in a planar view, and the collector-side terminal trench structure penetrates the collector layer on the side surface side of the semiconductor substrate with respect to the connecting portion between the collector electrode and the collector layer in a cross-sectional view.

Inventors

• Masaki Sudo
• Masanori Tsukuda
• Takuya Yoshida
• Shunsuke SAKAMOTO
• Yosuke Nakanishi

Assignees

• MITSUBISHI ELECTRIC CORPORATION

Dates

Publication Date

20260507

Application Date

20251023

Priority Date

20241106

Claims (20)

1. 1 . A semiconductor device comprising: a semiconductor substrate having a front surface and a back surface on which an element region and a termination region surrounding the element region are defined; an emitter electrode disposed on the front surface side of the semiconductor substrate; an emitter-side element trench structure that is disposed on the front surface side of the semiconductor substrate in the element region, and includes an emitter-side gate electrode insulated from the emitter electrode; an emitter-side gate pad that is disposed on the front surface side of the semiconductor substrate in the termination region, is insulated from the emitter electrode, and is electrically connected to the emitter-side gate electrode; a collector electrode disposed on the back surface side of the semiconductor substrate; a collector-side element trench structure that is disposed on the back surface side of the semiconductor substrate in the element region, and includes a collector-side gate electrode insulated from the collector electrode; a collector-side gate pad that is disposed on the back surface side of the semiconductor substrate in the termination region, is insulated from the collector electrode, and is electrically connected to the collector-side gate electrode; and a collector-side terminal trench structure that is disposed on the back surface side of the semiconductor substrate in the termination region, and includes a collector-side terminal electrode, wherein the semiconductor substrate includes: a drift layer of a first conductivity type; a buffer layer of the first conductivity type that is disposed on the back surface side of the drift layer; and a collector layer of a second conductivity type that is disposed on the back surface side of the buffer layer, in a planar view, a side surface of the semiconductor substrate and the collector electrode surround the collector-side gate pad, and, in a cross-sectional view, the collector-side terminal trench structure penetrates the collector layer on the side surface side of the semiconductor substrate with respect to a connecting portion between the collector electrode and the collector layer.
2. 2 . The semiconductor device according to claim 1 , wherein, in a cross-sectional view, the collector-side terminal trench structure penetrates the collector layer at the side surface of the semiconductor substrate.
3. 3 . The semiconductor device according to claim 1 , wherein a depth of the collector-side terminal trench structure is greater than a depth of the collector-side element trench structure.
4. 4 . The semiconductor device according to claim 1 , wherein a width of the collector-side terminal trench structure is greater than a width of the collector-side element trench structure.
5. 5 . The semiconductor device according to claim 1 , wherein, in a cross-sectional view, the collector-side terminal trench structure penetrates the collector layer on the connecting portion side with respect to the side surface of the semiconductor substrate.
6. 6 . The semiconductor device according to claim 1 , further comprising a passivation film that is disposed on the back surface side of the semiconductor substrate, and on the collector-side gate pad on the side surface side of the semiconductor substrate.
7. 7 . The semiconductor device according to claim 1 , further comprising a passivation film that is disposed on the back surface side of the semiconductor substrate, and on the collector-side gate pad on the collector electrode side.
8. 8 . The semiconductor device according to claim 2 , wherein, in a planar view, a trench corner portion of the collector-side terminal trench structure is rounded, the trench corner portion corresponding to a corner portion of the semiconductor substrate.
9. 9 . The semiconductor device according to claim 2 , wherein, in a planar view, a width of a trench corner portion of the collector-side terminal trench structure is greater than a width of a linear portion of the collector-side terminal trench structure, the trench corner portion corresponding to a corner portion of the semiconductor substrate, the linear portion being connected to the trench corner portion.
10. 10 . The semiconductor device according to claim 1 , wherein, in a planar view, a distance between the collector-side gate pad and the collector electrode is longer than a distance between the collector-side gate pad and the side surface of the semiconductor substrate.
11. 11 . A semiconductor device comprising: a semiconductor substrate having a front surface and a back surface on which an element region and a termination region surrounding the element region are defined; an emitter electrode disposed on the front surface side of the semiconductor substrate; an emitter-side element trench structure that is disposed on the front surface side of the semiconductor substrate in the element region, and includes an emitter-side gate electrode insulated from the emitter electrode; an emitter-side gate pad that is disposed on the front surface side of the semiconductor substrate in the termination region, is insulated from the emitter electrode, and is electrically connected to the emitter-side gate electrode; a collector electrode disposed on the back surface side of the semiconductor substrate; a collector-side element trench structure that is disposed on the back surface side of the semiconductor substrate in the element region, and includes a collector-side gate electrode insulated from the collector electrode; and a collector-side gate pad that is disposed on the back surface side of the semiconductor substrate in the termination region, is insulated from the collector electrode, and is electrically connected to the collector-side gate electrode, wherein the semiconductor substrate includes: a drift layer of a first conductivity type; a buffer layer of the first conductivity type that is disposed on the back surface side of the drift layer; and a collector layer of a second conductivity type that is disposed on the back surface side of the buffer layer, in a planar view, a side surface of the semiconductor substrate and the collector electrode surround the collector-side gate pad, and, in a cross-sectional view, the buffer layer penetrates the collector layer on the side surface side of the semiconductor substrate with respect to a connecting portion between the collector electrode and the collector layer.
12. 12 . A semiconductor device comprising: a semiconductor substrate having a front surface and a back surface on which an element region and a termination region surrounding the element region are defined; an emitter electrode disposed on the front surface side of the semiconductor substrate; an emitter-side element trench structure that is disposed on the front surface side of the semiconductor substrate in the element region, and includes an emitter-side gate electrode insulated from the emitter electrode; an emitter-side gate pad that is disposed on the front surface side of the semiconductor substrate in the termination region, is insulated from the emitter electrode, and is electrically connected to the emitter-side gate electrode; a collector electrode disposed on the back surface side of the semiconductor substrate; a collector-side element trench structure that is disposed on the back surface side of the semiconductor substrate in the element region, and includes a collector-side gate electrode insulated from the collector electrode; and a collector-side gate pad that is disposed on the back surface side of the semiconductor substrate in the termination region, is insulated from the collector electrode, and is electrically connected to the collector-side gate electrode, wherein the semiconductor substrate includes: a drift layer of a first conductivity type; a buffer layer of the first conductivity type that is disposed on the back surface side of the drift layer; and a collector layer of a second conductivity type that is disposed on the back surface side of the buffer layer, and the semiconductor device further comprises a modified layer that is disposed in a portion of a surface of at least one of the collector-side gate pad or the collector electrode in a cross-sectional view, and has lower solder wettability than solder wettability of a remaining portion of the surface.
13. 13 . The semiconductor device according to claim 12 , wherein the portion in which the modified layer is disposed includes a portion of the collector-side gate pad on a side surface side of the semiconductor substrate.
14. 14 . The semiconductor device according to claim 12 , wherein the portion in which the modified layer is disposed includes a portion of the collector-side gate pad on the collector electrode side.
15. 15 . The semiconductor device according to claim 12 , wherein the portion in which the modified layer is disposed includes at least a portion of an outer peripheral portion of the collector electrode in a planar view.
16. 16 . A semiconductor device comprising: a semiconductor substrate having a front surface and a back surface on which an element region and a termination region surrounding the element region are defined; an emitter electrode disposed on the front surface side of the semiconductor substrate; an emitter-side element trench structure that is disposed on the front surface side of the semiconductor substrate in the element region, and includes an emitter-side gate electrode insulated from the emitter electrode; and an emitter-side gate pad that is disposed on the front surface side of the semiconductor substrate in the termination region, is insulated from the emitter electrode, and is electrically connected to the emitter-side gate electrode, wherein the semiconductor device further comprises a modified layer that is disposed in a portion of a surface of at least one of the emitter-side gate pad or the emitter electrode in a cross-sectional view, and has lower solder wettability than solder wettability of a remaining portion of the surface.
17. 17 . The semiconductor device according to claim 16 , wherein the portion in which the modified layer is disposed includes a portion of the emitter-side gate pad on a side surface side of the semiconductor substrate.
18. 18 . The semiconductor device according to claim 16 , wherein the portion in which the modified layer is disposed includes a portion of the emitter-side gate pad on the emitter electrode side.
19. 19 . The semiconductor device according to claim 16 , wherein the portion in which the modified layer is disposed includes at least a portion of an outer peripheral portion of the emitter electrode in a planar view.
20. 20 . The semiconductor device according to claim 12 , wherein the modified layer is at least one of an oxidized layer of the surface or a roughened layer of the surface.

Description

BACKGROUND Technical Field The present disclosure relates to a semiconductor device. Description of the Background Art There are proposed semiconductor devices each including: an emitter-side gate electrode forming a channel on an emitter electrode side that is the front side; and a collector-side gate electrode forming a channel on a collector electrode side that is the back side. Various techniques have been proposed for such semiconductor devices having a double-sided gate structure. For example, Japanese Patent Application Laid-Open No. 2010-123667 proposes a configuration in which a collector-side lead frame for electrically connecting to the outside is connected, by solder, to a collector-side gate pad disposed on the back surface side of a semiconductor substrate. With such a configuration, it is possible to form a channel on the back surface side of the semiconductor substrate by applying a voltage from outside to the collector-side gate electrode via the collector-side lead frame and the collector-side gate pad. However, there are cases where, during the manufacturing process, the solder connecting the collector-side gate pad and the collector-side lead frame leaks to a side surface of the semiconductor substrate. This causes a problem in that the collector-side lead frame and the side surface of the semiconductor substrate are electrically connected by the solder, and the leakage current of the collector-side gate increases. SUMMARY The present disclosure has been made in view of the above problems, and aims to provide a technology that can reduce leakage current of the collector-side gate. A semiconductor device according to the present disclosure includes: a semiconductor substrate having a front surface and a back surface on which an element region and a termination region surrounding the element region are defined; an emitter electrode disposed on the front surface side of the semiconductor substrate; an emitter-side element trench structure that is disposed on the front surface side of the semiconductor substrate in the element region, and includes an emitter-side gate electrode insulated from the emitter electrode; an emitter-side gate pad that is disposed on the front surface side of the semiconductor substrate in the termination region, is insulated from the emitter electrode, and is electrically connected to the emitter-side gate electrode; a collector electrode disposed on the back surface side of the semiconductor substrate; a collector-side element trench structure that is disposed on the back surface side of the semiconductor substrate in the element region, and includes a collector-side gate electrode insulated from the collector electrode; a collector-side gate pad that is disposed on the back surface side of the semiconductor substrate in the termination region, is insulated from the collector electrode, and is electrically connected to the collector-side gate electrode; and a collector-side terminal trench structure that is disposed on the back surface side of the semiconductor substrate in the termination region, and includes a collector-side terminal electrode, wherein the semiconductor substrate includes: a drift layer of a first conductivity type; a buffer layer of the first conductivity type that is disposed on the back surface side of the drift layer; and a collector layer of a second conductivity type that is disposed on the back surface side of the buffer layer, a side surface of the semiconductor substrate and the collector electrode surround the collector-side gate pad in a planar view, and the collector-side terminal trench structure penetrates the collector layer on the side surface side of the semiconductor substrate with respect to a connecting portion between the collector electrode and the collector layer in a cross-sectional view. Leakage current of the collector-side gate can be reduced. These and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view illustrating a configuration of the front side of a semiconductor device according to a first preferred embodiment; FIG. 2 is a plan view illustrating a configuration of the back side of the semiconductor device according to the first preferred embodiment; FIG. 3 is a cross-sectional view illustrating a configuration of the semiconductor device according to the first preferred embodiment; FIG. 4 is a cross-sectional view illustrating a configuration of a semiconductor device according to a second preferred embodiment; FIG. 5 is a cross-sectional view illustrating a configuration of a semiconductor device according to a third preferred embodiment; FIG. 6 is a plan view illustrating a configuration of the back side of a semiconductor device according to a fourth preferred embodiment; FIG. 7 is a c