# US 11,114,572 B2 · Semiconductor device and method for manufacturing semiconductor device

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- Number: US 11,114,572 B2
- Document ID: US11114572B2
- Status: Granted
- Kind: B2
- Application number: 16/905,612
- Filed: 2020-06-18
- Published: 2020-12-24
- Granted: 2021-09-07
- Earliest claimed: 2019-06-20
- Assignees: Rohm Co., Ltd.
- Applicants: Rohm Co., Ltd.
- Inventors: Yasushi Hamazawa
- Web page: https://patentgrep.com/patent/US11114572B2

## CPC

- H10D 8/25: Zener diodes
- H10D 8/022: {of Zener diodes}
- H10D 62/114: {PN junction isolations}
- H10D 62/126: {Top-view geometrical layouts of the regions or the junctions}
- H10D 62/129: {Cathode regions of diodes}
- H10D 64/117: {Recessed field plates, e.g. trench field plates or buried field plates}
- H10P 32/00: Diffusion of dopants within, into or out of wafers, substrates or parts of devices (during formation of materials H10P14/00)
- H10P 50/691: {for Group IV materials or Group III-V materials}
- H10W 72/075: {of bond wires}
- H10W 72/50: Bond wires
- H10D 62/8325: {Silicon carbide}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A semiconductor device includes a semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type embedded in the semiconductor layer, a first trench and a second trench formed in the semiconductor layer such that the first trench and the second trench penetrate the second semiconductor layer, a first insulating film formed on at least a side surface of the first trench, a second insulating film formed on at least a side surface of the second trench, a first sinker layer of the second conductivity type formed in a first portion of the semiconductor layer, a second sinker layer of the second conductivity type formed in the first portion of the semiconductor layer, a diode impurity region of the first conductivity type which is formed on the first surface of the semiconductor layer and forms a Zener diode by pn junction between the first sinker layer and the diode impurity region, a first wiring electrically connected to the diode impurity region, and a second wiring electrically connected to the second sinker layer.

## Claims

### Claim 1

A semiconductor device comprising:
a semiconductor layer of a first conductivity type having a first surface and a second surface on an opposite side to the first surface;
a second semiconductor layer of a second conductivity type embedded in the semiconductor layer;
a first trench and a second trench formed in the semiconductor layer such that the first trench and the second trench extend from the first surface in a thickness direction of the semiconductor layer and penetrate the second semiconductor layer in a sectional view in a direction intersecting the first surface;
a first insulating film formed on at least a side surface of the first trench;
a second insulating film formed on at least a side surface of the second trench;
a first sinker layer of the second conductivity type formed in a first portion of the semiconductor layer defined by the second semiconductor layer, the first trench and second trench such that the first sinker layer extends in a depth direction of the first trench and is in contact with the second semiconductor layer and the first insulating film;
a second sinker layer of the second conductivity type formed in the first portion of the semiconductor layer such that the second sinker layer extends in a depth direction of the second trench and is in contact with the second semiconductor layer and the second insulating film;
a diode impurity region of the first conductivity type which is formed on the first surface of the semiconductor layer and forms a Zener diode by pn junction between the first sinker layer and the diode impurity region;
a first wiring electrically connected to the diode impurity region; and
a second wiring electrically connected to the second sinker layer.

### Claim 2 (depends on 1)

The semiconductor device according to claim 1, wherein the first sinker layer is in contact with the first insulating film over the entire depth direction of the first trench.

### Claim 3 (depends on 1)

The semiconductor device according to claim 1, wherein the second sinker layer is in contact with the second insulating film over the entire depth direction of the second trench.

### Claim 4 (depends on 1)

The semiconductor device according to claim 1, wherein the first sinker layer has a thickness of 0.5 μm to 5 μm in a direction orthogonal to the depth direction of the first trench.

### Claim 5 (depends on 1)

The semiconductor device according to claim 1, wherein the second sinker layer has a thickness of 0.5 μm to 5 μm in a direction orthogonal to the depth direction of the second trench.

### Claim 6 (depends on 1)

The semiconductor device according to claim 1, wherein the second semiconductor layer has a thickness of 2 μm to 10 μm.

### Claim 7 (depends on 1)

The semiconductor device according to claim 1, further comprising:
a first impurity region of the first conductivity type formed on a bottom surface of the first trench and having a higher impurity concentration than the semiconductor layer; and
a first conductor that is embedded in the first trench through the first insulating film and is in contact with the first impurity region.

### Claim 8 (depends on 1)

The semiconductor device according to claim 1, further comprising:
a second impurity region of the first conductivity type formed on a bottom surface of the second trench and having a higher impurity concentration than the semiconductor layer; and
a second conductor that is embedded in the second trench through the second insulating film and is in contact with the second impurity region.

### Claim 9 (depends on 1)

The semiconductor device according to claim 1, wherein the first insulating film is formed on a side surface and a bottom surface of the first trench, and
the semiconductor device includes a first conductor embedded in the first trench through the first insulating film.

### Claim 10 (depends on 1)

The semiconductor device according to claim 1, wherein the second insulating film is formed on a side surface and a bottom surface of the second trench, and
the semiconductor device includes a second conductor embedded in the second trench through the second insulating film.

### Claim 11 (depends on 1)

The semiconductor device according to claim 1, wherein the second sinker layer is formed in an annular shape surrounding the first sinker layer in a plan view in a direction along the first surface.

### Claim 12 (depends on 1)

The semiconductor device according to claim 1, wherein the first sinker layer and the second sinker layer are formed in linear shapes parallel to each other in a plan view in a direction along the first surface.

### Claim 13

A method for manufacturing a semiconductor device, the method comprising:
a step of forming a first trench and a second trench by selectively removing, through a mask, a semiconductor layer of a first conductivity type which has a first surface and a second surface on an opposite side to the first surface and in which a second semiconductor layer of a second conductivity type is embedded, with the first trench and the second trench extending from the first surface in a thickness direction of the semiconductor layer and penetrating the second semiconductor layer in a sectional view in a direction intersecting the first surface;
a step of implanting an impurity of the second conductivity type into side surfaces of the first trench and the second trench while the mask is left on the semiconductor layer;
a step of forming a first insulating film on at least a side surface of the first trench;
a step of forming a second insulating film on at least a side surface of the second trench;
a step of forming a first sinker layer of the second conductivity type and a second sinker layer of the second conductivity type by heat diffusion of an impurity of the second conductivity type such that the first sinker layer extends in a depth direction of the first trench and is in contact with the second semiconductor layer and the first insulating film, and the second sinker layer extends in a depth direction of the second trench and is in contact with the second semiconductor layer and the second insulating film;
a step of forming a diode impurity region of the first conductivity type on the first surface of the semiconductor layer so as to be in contact with the first sinker layer;
a step of forming a first wiring so as to be electrically connected to the diode impurity region; and
a step of forming a second wiring so as to be electrically connected to the second sinker layer.

### Claim 14 (depends on 13)

The method for manufacturing the semiconductor device according to claim 13, wherein the step of implanting the impurity of the second conductivity type includes a step of implanting an impurity at a tilt angle of 3° to 7° with respect to a normal direction of the first surface of the semiconductor layer.