Semiconductor device

• US 10,825,923 B2
• Filed: 06/24/2019
• Issued: 11/03/2020
• Est. Priority Date: 07/15/2015
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Inventors: Naito, Tatsuya
• Primary Examiner(s): Reddington, Patricia D
• Application Number:
  US16/449,469
• Publication Number:
  US 20190312135A1
• Time in Patent Office: 498 Days
• CPC Class Codes: H01L 29/0619 with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
• CPC Class Codes: H01L 29/0623 Buried supplementary region, e.g. buried guard ring multi-RESURF H01L29/0634
• CPC Class Codes: H01L 29/0649 Dielectric regions, e.g. SiO2 regions, air gaps
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/0834 Anode regions of thyristors or gated bipolar-mode devices, e.g. supplementary regions surrounding anode regions
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/402 Field plates
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/4236 within a trench, e.g. trench gate electrode, groove gate electrode
• CPC Class Codes: H01L 29/66348 with a recessed gate
• CPC Class Codes: H01L 29/7397 and a gate structure lying on a slanted or vertical surface or formed in a groove, e.g. trench gate IGBT
• CPC Class Codes: H01L 29/861 Diodes

Abstract

A semiconductor device is provided comprising a semiconductor substrate of a first conductivity type and a dummy trench portion having a main body portion and one or more branch portions, the main body portion formed in a front surface of the semiconductor substrate and extending in a predetermined extending direction, the branch portions extending from the main body portion in directions different from the extending direction. The semiconductor substrate has an emitter region of first conductivity type and a base region of a second conductivity type which are provided sequentially from the front surface side of the semiconductor substrate, and the dummy trench portion has a dummy trench which penetrates the emitter region and the base region from the front surface of the semiconductor substrate, and a dummy insulating portion which is provided within the dummy trench.

Claims

1. A semiconductor device comprising:

a semiconductor substrate of a first conductivity type; and

a dummy trench portion having a main body portion and one or more branch portions, the main body portion formed in a front surface of the semiconductor substrate and extending in a predetermined extending direction, the one or more branch portions extending at least to a point equal to a width of the main body portion distant from the main body portion and less than a distance to a gate trench portion, from the main body portion in directions different from the extending direction; and

a gate trench portion formed in the front surface of the semiconductor substrate, wherein

the semiconductor substrate has an emitter region of a first conductivity type and a base region of a second conductivity type which are provided sequentially from the front surface side of the semiconductor substrate,

the dummy trench portion has a dummy trench which penetrates the emitter region and the base region from the front surface of the semiconductor substrate, and a dummy insulating portion which is provided within the dummy trench,

the dummy insulating portion is filled from a bottom portion of the dummy trench to a predetermined height within the dummy trench,

the gate trench portion has a gate trench which penetrates the emitter region and the base region of the semiconductor substrate, and a gate conductive portion which is provided inside the gate trench,

the main body portion of the dummy trench portion is provided to face the gate trench,

the one or more branch portions of the dummy trench portion are provided to extend toward the gate trench,

at least some of the one or more branch portions of the dummy trench portion are not in contact with the gate trench,

the semiconductor substrate further has a contact region of a second conductivity type which is connected with the base region, has an impurity concentration higher than that of the base region and is exposed in the front surface of the semiconductor substrate,

at least some of the one or more branch portions are provided inside the contact region in the front surface of the semiconductor substrate,

at least some of the one or more branch portions of the dummy trench portion are provided inside the emitter region in the front surface of the semiconductor substrate, and

the one or more branch portions provided inside of the emitter region in the front surface of the semiconductor substrate are not in contact with the gate trench.

2. The semiconductor device according to claim 1, wherein

the emitter region and the contact region are provided alternately along the extending direction in a region sandwiched by the gate trench portion and the dummy trench portion in the front surface of the semiconductor substrate, and

the number of the one or more branch portions provided in the contact region in the front surface of the semiconductor substrate is greater than the number of the one or more branch portions provided in the emitter region.

3. The semiconductor device according to claim 1, wherein

in the extending direction of the main body portion, each interval between the one or more branch portions is fixed.

4. The semiconductor device according to claim 2, wherein

in the extending direction of the main body portion, each interval between the one or more branch portions is fixed.

5. The semiconductor device according to claim 1, wherein

each interval between the one or more branch portions in the extending direction of the main body portion is shorter than a distance between the main body portion and the gate trench.

6. The semiconductor device according to claim 2, wherein

each interval between the one or more branch portions in the extending direction of the main body portion is shorter than a distance between the main body portion and the gate trench.

7. The semiconductor device according to claim 1, wherein

the dummy trench is formed reaching to a position shallower than the gate trench.

8. The semiconductor device according to claim 1, wherein

a width of the dummy trench in the main body portion is shorter than a width of the gate trench.

9. The semiconductor device according to claim 1, wherein

the semiconductor substrate further has an accumulation region of a first conductivity type which is provided in a back surface side of the base region and has an impurity concentration higher than that of the semiconductor substrate, and

the dummy trench further penetrates the accumulation region.

10. The semiconductor device according to claim 1, wherein

the semiconductor substrate further has a floating region of a second conductivity type separated from the base region in a region adjacent to the bottom portion of the dummy trench.

11. The semiconductor device according to claim 10, wherein

a bottom portion of the floating region is provided in a position deeper than a bottom portion of the gate trench.

12. The semiconductor device according to claim 1, wherein

the semiconductor substrate further has a well region of a second conductivity type which is provided outside the emitter region in the front surface of the semiconductor substrate and has an impurity concentration higher than that of the base region, and

the dummy trench of one of the one or more branch portions provided in a position closest to the well region in the extending direction is formed reaching to a position deeper than the dummy trench of others of the one or more branch portions.

13. The semiconductor device according to claim 12, wherein

a distance across the dummy trench of the one of the one or more branch portions closest to the well region is greater than a distance across the dummy trench of the others of the one or more branch portions.

14. The semiconductor device according to claim 1, further comprising:

a first front surface side electrode which is provided above the front surface of the semiconductor substrate and is in contact with a front surface of the emitter region, wherein

the dummy insulating portion is filled within the dummy trench such that at least a part of the emitter region is exposed on a side wall of the dummy trench, and

the first front surface side electrode is also in contact with the emitter region in the side wall of the dummy trench.

15. The semiconductor device according to claim 14, wherein

the gate trench portion further has a gate insulating portion which is provided above the gate conductive portion inside the gate trench and insulates the first front surface side electrode from the gate conductive portion.

16. The semiconductor device according to claim 1, wherein

the gate trench portion includes at least one or more additional branch portions extending in directions different from the extending direction.

17. The semiconductor device according to claim 1, wherein

the dummy trench portion is embedded with only an oxide film from a bottom portion through to the first front surface side emitter electrode.

18. The semiconductor device according to claim 1, wherein

the one or more branch portions extend in directions orthogonal to the extending direction of the main body portion.

19. The semiconductor device according to claim 1, wherein

an extension amount of the one or more branch portions from the main body portion is equal to or longer than a half of a distance between the main body portion of the dummy trench portion and the gate trench.