# US 9,520,398 B1 · Including low and high-voltage CMOS devices in CMOS process

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- Number: US 9,520,398 B1
- Document ID: US9520398B1
- Status: Granted
- Kind: B1
- Application number: 14/818,280
- Filed: 2015-08-04
- Published: 2016-12-29
- Granted: 2016-12-13
- Earliest claimed: 2015-06-25
- Assignees: Broadcom Corporation
- Applicants: Broadcom Corporation
- Inventors: Akira Ito
- Web page: https://patentgrep.com/patent/US9520398B1

## CPC

- H10D 84/856: {the complementary IGFETs having different architectures than each other, e.g. high-voltage and low-voltage CMOS}
- H10D 84/0191: {Manufacturing their doped wells}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10W 10/031: {of isolation regions comprising PN junctions}
- H10W 10/30: Isolation regions comprising PN junctions
- H10D 30/601: {having lightly-doped drain or source extensions, e.g. LDD IGFETs or DDD IGFETs (lightly doped source or drain extensions for TFTs H10D30/6715)}
- H10D 62/371: {Inactive supplementary semiconductor regions, e.g. for preventing punch-through, improving capacity effect or leakage current}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A device includes a substrate, a deep well, a first well, and a second well. The deep well is formed in the substrate. The first well includes a first portion formed on the deep well and a second portion formed in the substrate. The second well is formed partially on the deep well. A first separator structure is formed on the deep well to isolate the first portion of the first well from the second well, and a second separator structure is formed on the substrate to isolate the second well and a second portion of the first well.

## Claims

### Claim 1

A device comprising:
a substrate;
a deep well formed in the substrate;
a first well comprising a first portion formed on the deep well and a second portion formed in the substrate;
a second well formed partially on the deep well;
a first separator structure formed on the deep well and configured to isolate the first portion of the first well from the second well; and
a second separator structure formed on the substrate and configured to isolate the second well and a second portion of the first well.

### Claim 2 (depends on 1)

The device of claim 1, wherein the substrate comprises a semiconductor substrate, wherein the first and the second separator structures comprise native semiconductor layers and are configured to provide an isolated high-voltage domain.

### Claim 3 (depends on 2)

The device of claim 2, wherein the first portion of the first well comprises a channel of an MOS transistor and a body-tie region formed in the isolated high-voltage domain.

### Claim 4 (depends on 3)

The device of claim 3, wherein the body-tie region and the channel of the MOS transistor are separated from a first and a second edge of the first well by a first and a second distance, respectively, wherein the first distance is larger than 80 nanometers and the second distance is approximately 160 nanometers.

### Claim 5 (depends on 4)

The device of claim 4, wherein the deep well comprises a deep Nwell, the first well comprises a Pwell, the second well comprises an Nwell, the body-tie region comprises a highly-doped ρ-region, and the MOS transistor comprises an NMOS transistor, and wherein a width of the second well is larger than 1 micrometer and a separation between the second well and the first well is larger than 1 micrometer.

### Claim 6

A device comprising:
a substrate;
a first well formed on the substrate;
a second well formed on the substrate;
a separator structure formed on the substrate and configured to isolate the first well from the second well;
an MOS transistor formed in the second well;
a body-tie region formed in the second well; and
an optional deep Nwell,
wherein the separator structure comprises a native semiconductor layer configured to provide an isolated hi h-voltage domain.

### Claim 7 (depends on 6)

The device of claim 6, wherein the first well comprises a Pwell, the second well comprises an Nwell, the body-tie region comprises a highly-doped n-region, and the MOS transistor comprises a PMOS transistor.

### Claim 8 (depends on 6)

The device of claim 6, wherein the body-tie region and the channel of the MOS transistor are separated from a first and a second edge of the second well by a first distance, and wherein the first distance is larger than 80 nanometers, and wherein a separation between the first well and the second well is larger than 1 micrometer.

### Claim 9 (depends on 6)

The device of claim 6, wherein the optional deep Nwell extends under the a portion of the first well and a portion of the second well, wherein an edge of the optional deep Nwell is at a second distance form an edge of the second well.

### Claim 10 (depends on 6)

The device of claim 6, wherein a breakdown voltage between the first well and the second well is greater than a breakdown voltage between the first well and the deep Nwell.

### Claim 11

A method for including low and high-voltage CMOS devices in CMOS process, the method comprising:
providing a substrate;
forming a deep well in the substrate;
forming a first well comprising a first portion formed on the deep well and a second portion formed in the substrate;
forming a second well partially on the deep well;
forming a first separator structure on the deep well, and configuring the first separator structure to isolate the first portion of the first well from the second well; and
forming a second separator structure on the substrate, and configuring the second separator structure to isolate the second well and a second portion of the first well.

### Claim 12 (depends on 11)

The method of claim 11, wherein providing the substrate comprises providing a semiconductor substrate, wherein forming the first and the second separator structures comprise forming native semiconductor layers, and wherein the method further comprises configuring the first and the second separator structures to provide an isolated high-voltage domain.

### Claim 13 (depends on 12)

The method of claim 12, further comprising forming, in the first portion of the first well, a channel of an MOS transistor and forming a body-tie region in the isolated high-voltage domain.

### Claim 14 (depends on 13)

The method of claim 13, wherein forming the body-tie region and the channel of the MOS transistor to be separated from a first and a second edge of the first well by a first and a second distance, respectively, wherein the first distance is larger than 80 nanometers and the second distance is approximately 160 nanometers.

### Claim 15 (depends on 14)

The method of claim 14, wherein:
forming the deep well comprises forming a deep Nwell,
forming the first well comprises forming a Pwell,
forming the second well comprises forming an Nwell,
forming the body-tie region comprises forming a highly-doped p-region,
the MOS transistor comprises an NMOS transistor, and
a width of the second well is larger than 1 micrometer and a separation between the second well and the first well is larger than 1 micrometer.

### Claim 16

A method for including low and high-voltage CMOS devices in CMOS process, the method comprising:
providing a substrate;
forming a first well on the substrate;
forming a second well on the substrate;
forming a separator structure on the substrate and configuring the separator structure to isolate the first well from the second well;
forming an MOS transistor in the second well; and
forming a body-tie region in the second well and an optional deer Nwell,
wherein the separator structure comprises a native semiconductor layer configured to provide an isolated high-voltage domain.

### Claim 17 (depends on 16)

The method of claim 16, wherein:
forming the first well comprises forming a Pwell,
forming the second well comprises forming an Nwell,
forming the body-tie region comprises forming a highly-doped n-region, and
the MOS transistor comprises a PMOS transistor.

### Claim 18 (depends on 16)

The method of claim 16, wherein forming the body-tie region and the channel of the MOS transistor to be separated from a first and a second edge of the second well by a first distance, and wherein the first distance is larger than 80 nanometers, and wherein a separation between the first well and the second well is larger than 1 micrometer.

### Claim 19 (depends on 16)

The method of claim 16, wherein:
forming the optional deep Nwell comprises extending the optional deep Nwell under the a portion of the first well and a portion of the second well, and
forming the optional deep Nwell comprises allowing an edge of the optional deep Nwell to be at a second distance form an edged of the second well.

### Claim 20 (depends on 16)

The method of claim 16, wherein a breakdown voltage between the first well and the second well is greater than a breakdown voltage between the first well and the deep Nwell.
