# US 11,908,896 B2 · Integrated circuit structure with non-gated well tap cell

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- Number: US 11,908,896 B2
- Document ID: US11908896B2
- Status: Granted
- Kind: B2
- Application number: 17/859,731
- Filed: 2022-07-07
- Published: 2022-11-03
- Granted: 2024-02-20
- Earliest claimed: 2018-06-28
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Jiefeng Lin; Jeng-Ya Yeh; Chih-Yung Lin
- Web page: https://patentgrep.com/patent/US11908896B2

## CPC

- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- H10W 10/012: {using local oxidation of silicon [LOCOS]}
- H10D 30/6219: {characterised by the source or drain electrodes}
- H10D 84/834: {comprising FinFETs}
- H10P 14/2905: {Silicon, silicon germanium or germanium}
- H10P 14/3444: {P-type}
- H10P 52/402: {of semiconductor materials}
- H10P 95/90: Thermal treatments, e.g. annealing or sintering
- H10W 10/014: {using trench refilling with dielectric materials, e.g. shallow trench isolations}
- H10W 10/13: formed using local oxidation of silicon [LOCOS], e.g. sealed interface localised oxidation [SILO] or side-wall mask isolation [SWAMI]
- H10W 10/17: formed using trench refilling with dielectric materials, e.g. shallow trench isolations
- H10D 84/83135: {the IGFETs characterised by having different gate conductor materials or different gate conductor implants}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

The present disclosure provides a method that includes receiving a semiconductor substrate that includes an integrated circuit (IC) cell and a well tap cell surrounding the IC cell; forming first fin active regions in the well tap cell and second fin active regions in the IC cell; forming a hard mask within the well tap cell, wherein the hard mask includes openings that define first source/drain (S/D) regions on the first fin active region of the well tap cell; forming gate stacks on the second fin active regions within the IC cell and absent from the well tap cell, wherein the gate stacks define second S/D regions on the second fin active regions; epitaxially growing first S/D features in the first S/D regions using the hard mask to constrain the epitaxially growing; and forming contacts landing on the first S/D features within the well tap cell.

## Claims

### Claim 1

An integrated circuit (IC) structure, comprising:
a semiconductor substrate having an IC cell with field-effect transistors (FETs) and a well tap cell surrounding the IC cell;
a doped well continuously extended from the well tap cell to the IC cell such that the IC cell and the well tap cell are within the doped well;
first active regions formed within the well tap cell and second active regions formed on the IC cell;
first source/drain (S/D) features formed on the first active regions and second S/D features formed on the second active regions;
gate stacks formed on the second active regions, wherein the well tap cell is free of any gate electrode; and
first contacts formed on the first S/D features and second contacts formed the second S/D features.

### Claim 2 (depends on 1)

The IC structure of claim 1, wherein the first contacts are connected to a power line to bias the doped well to provide reliable and consistent device performance of the IC cell.

### Claim 3 (depends on 2)

The IC structure of claim 2, wherein
the IC cell includes an edge oriented in a first direction;
the well tap cell includes a segment oriented in the first direction and adjacent the edge of the IC cell; and
the first active regions in the segment of the well tap cell include two active regions in parallel and oriented in the first direction.

### Claim 4 (depends on 3)

The IC structure of claim 3, wherein one of the first S/D features continuously extends from one of the two active regions to another one of the two active regions.

### Claim 5 (depends on 4)

The IC structure of claim 4, wherein
each of the first and second active regions is surrounded by a shallow trench isolation (STI) feature; and
a corresponding one of the first contacts continuously extends from a top surface of the one of the first S/D features and a top surface of the STI feature.

### Claim 6 (depends on 5)

The IC structure of claim 5, further comprising a hard mask disposed on the first active regions and being adjacent the first S/D features.

### Claim 7 (depends on 6)

The IC structure of claim 6, wherein
the gate stacks are adjacent the edge the IC cell; and
the hard mask includes portions in the segment of the well tap cell, the portions of the hard mask being extended over the two active regions and aligned with the gate stacks, respectively.

### Claim 8 (depends on 7)

The IC structure of claim 7, wherein
the FETs are analog n-type FETs;
the doped well is a p-type doped well; and
the hard mask is free from the IC cell.

### Claim 9

An integrated circuit (IC) structure, comprising:
a semiconductor substrate having an IC cell with field-effect transistors (FETs) and a well tap cell surrounding the IC cell;
a doped well continuously extended from the well tap cell to the IC cell such that the IC cell and the well tap cell are within the doped well;
first active regions formed within the well tap cell and second active regions formed on the IC cell;
first source/drain (S/D) features formed on the first active regions and second S/D features formed on the second active regions;
gate stacks formed on the second active regions, wherein the well tap cell is free of any gate electrode;
first contacts formed on the first S/D features and second contacts formed the second S/D features; and
a hard mask disposed on the first active regions and being adjacent the first S/D features.

### Claim 10 (depends on 9)

The IC structure of claim 9, wherein
the IC cell includes an edge oriented in a first direction;
the well tap cell includes a segment oriented in the first direction and adjacent the edge of the IC cell; and
the first active regions in the segment of the well tap cell include two active regions in parallel and oriented in the first direction.

### Claim 11 (depends on 10)

The IC structure of claim 10, wherein
one of the first S/D features continuously extends from one of the two active regions to another one of the two active regions;
each of the first and second active regions is surrounded by a shallow trench isolation (STI) feature; and
a corresponding one of the first contacts continuously extends from a top surface of the one of the first S/D features and a top surface of the STI feature.

### Claim 12 (depends on 11)

The IC structure of claim 11, wherein
the gate stacks are adjacent the edge the IC cell; and
the hard mask includes portions in the segment of the well tap cell, the portions of the hard mask being extended over the two active regions and aligned with the gate stacks, respectively.

### Claim 13 (depends on 12)

The IC structure of claim 12, wherein
the FETs are analog n-type FETs;
the doped well is a p-type doped well; and
the hard mask is free from the IC cell.

### Claim 14 (depends on 13)

The IC structure of claim 13, wherein the first contacts are connected to a power line to bias the doped well to provide reliable and consistent device performance of the IC cell.

### Claim 15

A method, comprising:
receiving a semiconductor substrate that includes an integrated circuit (IC) cell and a well tap cell surrounding the IC cell;
forming first active regions in the well tap cell and second active regions in the IC cell, wherein each of the first and second active regions is surrounded by an isolation feature;
forming a hard mask within the well tap cell, wherein the hard mask includes openings that define first source/drain (S/D) regions on the first active regions of the well tap cell;
forming gate stacks on the second active regions within the IC cell and absent from the well tap cell, wherein the gate stacks define second S/D regions on the second active regions;
epitaxially growing first S/D features in the first S/D regions using the hard mask to constrain the epitaxially growing; and
forming contacts landing on the first S/D features within the well tap cell and extending to a top surface of the isolation feature.

### Claim 16 (depends on 15)

The method of claim 15, wherein the epitaxially growing further includes epitaxially growing second S/D features on the second S/D regions of the second active regions within the IC cell using the gate stacks to constrain the epitaxially growing.

### Claim 17 (depends on 15)

The method of claim 15, further comprising performing an etching process to recess the first S/D regions and the second S/D regions using the hard mask and gate stacks collectively as an etch mask.

### Claim 18 (depends on 15)

The method of claim 15, wherein the hard mask includes portions longitudinally aligned with the gate stacks, respectively.

### Claim 19 (depends on 15)

The method of claim 15, wherein
the forming of the first active regions in the well tap cell includes forming two active regions in parallel;
the well tap cell includes a segment along an edge of the IC cell; and
the two active regions are oriented and extended along the edge.

### Claim 20 (depends on 15)

The method of claim 15, wherein the forming a hard mask within the well tap cell includes
forming a dielectric material layer on the first and second active regions;
forming a patterned photoresist layer on the dielectric material layer by a lithography process; and
etching the dielectric material layer using the patterned photoresist layer as an etch mask, resulting in the hard mask being free from the IC cell.