# US 12,015,051 B2 · Semiconductor device and method of forming monolithic surge protection resistor

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- Number: US 12,015,051 B2
- Document ID: US12015051B2
- Status: Granted
- Kind: B2
- Application number: 17/449,600
- Filed: 2021-09-30
- Published: 2023-03-30
- Granted: 2024-06-18
- Earliest claimed: 2021-09-30
- Assignees: MACOM Technology Solutions Holdings, Inc.
- Applicants: MACOM Technology Solutions Holdings, Inc.
- Inventors: James J. Brogle; Timothy E. Boles
- Web page: https://patentgrep.com/patent/US12015051B2

## CPC

- H10D 1/042: {using deposition processes to form electrode extensions}
- H10D 1/043: {using patterning processes to form electrode extensions, e.g. etching}
- H10D 1/047: {of conductor-insulator-semiconductor capacitors, e.g. trench capacitors}
- H10D 1/665: {Trench conductor-insulator-semiconductor capacitors, e.g. trench MOS capacitors}
- H10D 1/716: {having vertical extensions}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A semiconductor device has a substrate and a first semiconductor layer with a high resistivity, such as an epitaxial layer with a resistivity in the range of 3000-5000 ohms/cm2, formed over the substrate. A second semiconductor layer is formed at least partially in the first semiconductor layer. A capacitor is formed at least partially over the first semiconductor layer. The capacitor has a plurality of trenches extending through the first semiconductor layer and into the substrate, and a first insulating layer formed in the trench. The trenches can be parallel, serpentine, or other geometric shape. The capacitor also has a second insulating layer formed over the first insulating layer, and a polysilicon layer formed over the second insulating layer. A conductive layer is formed over the capacitor. The first semiconductor layer with high resistivity provides a vertical path to discharge high voltage events incident on the capacitor.

## Claims

### Claim 1

A semiconductor device, comprising:
a substrate;
a first semiconductor layer comprising a high resistivity formed over a first surface of the substrate; and
a circuit element formed at least partially over the first semiconductor layer, wherein the circuit element includes,
(a) a trench extending through the first semiconductor layer and into the substrate,
(b) a first insulating layer formed in contact with a sidewall of the first semiconductor layer in the trench,
(c) a polysilicon layer formed over the first insulating layer, and
(d) a first conductive layer formed over a second surface of the substrate opposite the first surface of the substrate.

### Claim 2 (depends on 1)

The semiconductor device of claim 1, wherein the high resistivity of the first semiconductor layer is in the range of 3000-5000 ohms/cm2.

### Claim 3 (depends on 1)

The semiconductor device of claim 1, wherein the circuit element includes a capacitive structure comprising the polysilicon layer, first insulating layer, and first conductive layer.

### Claim 4 (depends on 3)

The semiconductor device of claim 3, wherein the capacitive structure further includes a second conductive layer formed over the semiconductor layer.

### Claim 5 (depends on 3)

The semiconductor device of claim 3, wherein the capacitive structure includes:
the trench extending through the first semiconductor layer and into the substrate; and
the first insulating layer formed in contact with the sidewall of the trench.

### Claim 6 (depends on 5)

The semiconductor device of claim 5, wherein the capacitive structure further includes:
a second insulating layer formed over the first insulating layer; and
the polysilicon layer formed over the second insulating layer.

### Claim 7

A semiconductor device, comprising:
a semiconductor material;
an epitaxial layer comprising a resistivity formed over a first surface of the semiconductor material; and
a circuit element formed at least partially over the epitaxial layer, wherein the circuit element includes,
(a) a trench extending through the epitaxial layer and into the semiconductor material,
(b) a first insulating layer formed over a sidewall of the epitaxial layer in the trench,
(c) a first conductive layer formed over the first insulating layer, and
(d) a second conductive layer formed over a second surface of the semiconductor material opposite the first surface of the semiconductor material.

### Claim 8 (depends on 7)

The semiconductor device of claim 7, wherein the resistivity of the epitaxial layer is in the range of 3000-5000 ohms/cm2.

### Claim 9 (depends on 7)

The semiconductor device of claim 7, wherein the circuit element includes a capacitor comprising the first conductive layer, first insulating layer, and second conductive layer.

### Claim 10 (depends on 9)

The semiconductor device of claim 9, wherein the capacitor extends through the epitaxial layer and into the semiconductor material.

### Claim 11 (depends on 9)

The semiconductor device of claim 9, wherein the capacitor further includes a third conductive layer formed over the epitaxial layer.

### Claim 12 (depends on 7)

The semiconductor device of claim 7, wherein the capacitor further includes:
a second insulating layer formed over the first insulating layer; and
the first conductive layer formed over the second insulating layer.

### Claim 13 (depends on 7)

The semiconductor device of claim 7, further including a semiconductor layer formed at least partially in the epitaxial layer.

### Claim 14

A method of making a semiconductor device, comprising:
providing a substrate;
forming a first semiconductor layer comprising a high resistivity over a first surface of the substrate; and
forming a circuit element at least partially over the first semiconductor layer, wherein forming the circuit element includes,
(a) forming a trench extending through the first semiconductor layer and into the substrate,
(b) forming a first insulating layer over a sidewall of the first semiconductor layer in the trench,
(c) forming a first conductive layer over the first insulating layer, and
(d) forming a second conductive layer over a second surface of the substrate opposite the first surface of the substrate.

### Claim 15 (depends on 14)

The method of claim 14, wherein the high resistivity of the first semiconductor layer is in the range of 3000-5000 ohms/cm2.

### Claim 16 (depends on 14)

The semiconductor device of claim 14, wherein the circuit element includes a capacitor comprising the first conductive layer, first insulating layer, and second conductive layer.

### Claim 17 (depends on 16)

The method of claim 16, wherein the capacitor extends through the first semiconductor layer and into the substrate.

### Claim 18 (depends on 16)

The method of claim 16, wherein forming the capacitor further includes forming a third conductive layer over the first semiconductor layer.

### Claim 19 (depends on 14)

The method of claim 14, wherein forming the capacitor further includes:
forming a second insulating layer over the first insulating layer; and
forming the first conductive layer over the second insulating layer.

### Claim 20 (depends on 14)

The method of claim 14, further including forming a second semiconductor layer at least partially in the first semiconductor layer.