# US 10,121,878 B1 · LDMOS finFET structures with multiple gate structures

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- Number: US 10,121,878 B1
- Document ID: US10121878B1
- Status: Granted
- Kind: B1
- Application number: 15/711,415
- Filed: 2017-09-21
- Granted: 2018-11-06
- Earliest claimed: 2017-09-21
- Assignees: Globalfoundries Inc.
- Applicants: GLOBALFOUNDRIES Inc.
- Inventors: Jerome Ciavatti; Jagar Singh; Hui Zang
- Web page: https://patentgrep.com/patent/US10121878B1

## CPC

- H10D 30/0285: {using formation of insulating sidewall spacers}
- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 30/0281: {of lateral DMOS [LDMOS] FETs}
- H10D 30/603: {having asymmetry in the channel direction, e.g. lateral high-voltage MISFETs having drain offset region or extended drain IGFETs [EDMOS]}
- H10D 30/6211: {having fin-shaped semiconductor bodies integral with the bulk semiconductor substrates}
- H10D 30/65: Lateral DMOS [LDMOS] FETs
- H10D 62/109: {Reduced surface field [RESURF] PN junction structures}
- H10D 62/152: {Source regions of DMOS transistors}
- H10D 64/011: {of electrodes ohmically coupled to a semiconductor}
- H10D 64/111: {Field plates}
- H10D 64/112: {comprising multiple field plate segments}
- H10D 64/511: {for IGFETs}
- H10P 30/22: using masks
- H10D 62/116: {adjoining the input or output regions of field-effect devices, e.g. adjoining source or drain regions}
- H10D 62/157: {Impurity concentrations or distributions}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Field-effect transistor structures for a laterally-diffused metal-oxide-semiconductor (LDMOS) device and methods of forming a LDMOS device. First and second fins are formed on a substrate. A first well of a first conductivity type is arranged partially in the substrate and partially in the first fin. A second well of a second conductivity type is arranged partially in the substrate, partially in the first fin, and partially in the second fin. First and second source/drain regions of the second conductivity type are respectively formed within the first well in the first fin and within the second well in the second fin. Spaced-apart gate structures are formed that overlap with respective portions of the first fin. A doped region of the first conductivity type is arranged within the second well in the first fin between the first and second gate structures.

## Claims

### Claim 1

A structure for a field-effect transistor that is formed using a substrate, the structure comprising:
a first fin and a second fin on the substrate;
a first well that is arranged partially in the substrate and partially in the first fin, the first well having a first conductivity type;
a second well that is arranged partially in the substrate, partially in the first fin, and partially in the second fin, the second well having a second conductivity type;
a first source/drain region of the second conductivity type within the first well in the first fin;
a second source/drain region of the second conductivity type within the second well in the second fin;
a first gate structure arranged to overlap with a first portion of the first fin;
a second gate structure arranged to overlap with a second portion of the first fin, the second gate structure spaced along the first fin from the first gate structure; and
a doped region arranged within the second well in the first fin between the first gate structure and the second gate structure, the doped region having the first conductivity type.

### Claim 2 (depends on 1)

The structure of claim 1 wherein the second well includes a first region and a second region in which the second source/drain region is arranged, the first region of the second well is arranged partially in the first fin and partially in the substrate between the first well and the second region of the second well, and the second region of the second well is located in the second fin.

### Claim 3 (depends on 2)

The structure of claim 2 wherein the first well and the first region of the second well converge along a junction, and the first region of the second well separates the first well from the second region of the second well.

### Claim 4 (depends on 3)

The structure of claim 3 wherein the first gate structure overlies the junction between the first well and the first region of the second well.

### Claim 5 (depends on 4)

The structure of claim 4 further comprising:
a trench isolation region between the first fin and the second fin,
wherein the first region of the second well and the second region of the second well converge beneath the trench isolation region.

### Claim 6 (depends on 2)

The structure of claim 2 wherein the first region of the second well is doped with a first concentration of a dopant providing the second conductivity type, the second region of the second well is doped with a second concentration of the dopant providing the second conductivity type, and the second concentration is greater than the first concentration.

### Claim 7 (depends on 2)

The structure of claim 2 wherein the doped region is coupled with the first region of the second well.

### Claim 8 (depends on 7)

The structure of claim 7 further comprising:
a trench isolation region between the first fin and the second fin,
wherein the second gate structure is arranged between the doped region and the trench isolation region.

### Claim 9 (depends on 2)

The structure of claim 2 wherein the first region of the second well surrounds the second region of the second well.

### Claim 10 (depends on 1)

The structure of claim 1 further comprising:
a third gate structure overlapping a third portion of the first fin, the third gate structure spaced along the first fin from the first gate structure, and the first gate structure and the third gate structure are arranged between the first source/drain region and the doped region.

### Claim 11 (depends on 1)

The structure of claim 1 wherein the doped region is not contacted.

### Claim 12 (depends on 1)

The structure of claim 1 further comprising:
a trench isolation region between the first fin and the second fin,
wherein a portion of the second gate structure has an overlapping relationship with the trench isolation region.

### Claim 13 (depends on 1)

The structure of claim 1 wherein the first conductivity type is n-type conductivity, and the second conductivity type is p-type conductivity.

### Claim 14

A method of fabricating a field-effect transistor, the method comprising:
forming a first fin and a second fin on a substrate;
forming a first well that is arranged partially in the substrate and partially in the first fin, the first well having a first conductivity type;
forming a second well that is arranged partially in the substrate, partially in the first fin, and partially in the second fin, the second well having a second conductivity type;
forming a first source/drain region of the second conductivity type within the first well in the first fin;
forming a second source/drain region of the second conductivity type within the second well in the second fin;
forming a first gate structure that overlaps with a first portion of the first fin;
forming a second gate structure that overlaps with a second portion of the first fin, the second gate structure is spaced along the first fin from the first gate structure; and
forming a doped region arranged within the second well in the first fin between the first gate structure and the second gate structure, the doped region having the first conductivity type.

### Claim 15 (depends on 14)

The method of claim 14 wherein the second well includes a first region and a second region in which the second source/drain region is arranged, the first region of the second well is arranged partially in the first fin and partially in the substrate between the first well and the second region of the second well, and the second region of the second well is located in the second fin.

### Claim 16 (depends on 15)

The method of claim 15 wherein the first well and the first region of the second well converge along a junction, and the first region of the second well separates the first well from the second region of the second well.

### Claim 17 (depends on 15)

The method of claim 15 wherein the doped region is directly coupled with the first region of the second well, and the first region of the second well is more lightly doped than the second region of the second well.

### Claim 18 (depends on 17)

The method of claim 17 further comprising:
forming a trench isolation region arranged between the first fin and the second fin,
wherein a portion of the second gate structure has an overlapping relationship with the trench isolation region, and the second gate structure is arranged between the doped region and the trench isolation region.

### Claim 19 (depends on 17)

The method of claim 17 further comprising:
forming a third gate structure overlapping a third portion of the first fin,
wherein the third gate structure is spaced along the first fin from the first gate structure, and the first gate structure and the third gate structure are arranged between the first source/drain region and the doped region.

### Claim 20 (depends on 14)

The method of claim 14 further comprising:
forming a trench isolation region between the first fin and the second fin,
wherein a portion of the second gate structure has an overlapping relationship with the trench isolation region.