# US 10,872,788 B2 · Wet etch apparatus and method for using the same

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- Number: US 10,872,788 B2
- Document ID: US10872788B2
- Status: Granted
- Kind: B2
- Application number: 16/542,119
- Filed: 2019-08-15
- Published: 2020-05-28
- Granted: 2020-12-22
- Earliest claimed: 2018-11-26
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Hong-Ting Lu; Han-Wen Liao
- Web page: https://patentgrep.com/patent/US10872788B2

## CPC

- H10P 72/0424: {using mainly spraying means, e.g. nozzles}
- H10D 30/024: {of fin field-effect transistors [FinFET]}
- H10D 64/017: {using dummy gates in processes wherein at least parts of the final gates are self-aligned to the dummy gates, i.e. replacement gate processes}
- H10D 64/021: {using multiple gate spacer layers, e.g. bilayered sidewall spacers}
- H10P 50/642: {Chemical etching}
- H10D 62/151: {of IGFETs (of IGFETs having LDD or DDD structure H10D30/601; of thin film transistors H10D30/6713)}
- H10P 50/264: {by chemical means}
- H10P 72/0414: {using mainly spraying means, e.g. nozzles}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method includes dispensing a liquid etchant onto a wafer, wherein the wafer is free from rotation during dispensing the liquid etchant; blowing the liquid etchant on the wafer using a gas flow, wherein a direction of the gas flow remains substantially constant during dispensing the liquid etchant; and turning the gas flow off after a target structure on the wafer is etched away by the liquid etchant.

## Claims

### Claim 1

A method, comprising:
forming a semiconductor fin on a substrate and extending in a first direction;
forming a dummy gate stack across the semiconductor fin and extending in a second direction;
forming a plurality of gate spacers respectively on opposite sides of the dummy gate stack;
applying a first liquid etchant on the dummy gate stack and blowing the first liquid etchant using a gas flow in the first direction to form a gate trench between the gate spacers; and
forming a metal gate structure in the gate trench.

### Claim 2 (depends on 1)

The method of claim 1, wherein the gas flow is a pure gas.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
applying a second liquid etchant on the dummy gate stack and blowing the second liquid etchant using the gas flow in the first direction to deepen the gate trench prior to forming the metal gate structure in the gate trench.

### Claim 4 (depends on 3)

The method of claim 3, wherein the gas flow is continuously ejected in a time span from blowing the first liquid etchant to blowing the second liquid etchant.

### Claim 5 (depends on 1)

The method of claim 1, wherein the gas flow is fixed in the first direction during blowing the first liquid etchant etching the dummy gate stack.

### Claim 6 (depends on 1)

The method of claim 1, further comprising:
moving a gas ejector and a gas extractor to a first position and a second position, respectively, wherein the first position is spaced apart from the second position along the first direction, and blowing the first liquid etchant comprises ejecting the gas flow from the gas ejector to the gas extractor after moving the gas ejector and the gas extractor.

### Claim 7 (depends on 1)

The method of claim 1, wherein blowing the first liquid etchant comprises:
turning on a first gas ejector closest to an end of the semiconductor fin;
turning off a first gas extractor closest to the end of the semiconductor fin;
turning off a second gas ejector furthest from the end of the semiconductor fin; and
turning on a second gas extractor furthest from the end of the semiconductor fin.

### Claim 8

A method, comprising:
forming a semiconductor fin on a substrate and extending in a first direction;
forming a dummy gate stack across a first portion of the semiconductor fin and extending in a second direction;
forming a source/drain feature over a second portion of the semiconductor fin;
forming an interlayer dielectric layer surrounding the dummy gate stack and the source/drain feature;
removing the dummy gate stack to form a gate trench in the interlayer dielectric layer, wherein removing the dummy gate stack comprises:
dispensing a liquid etchant onto the substrate; and
blowing the liquid etchant on the substrate using a gas flow; and
forming a metal gate structure in the gate trench.

### Claim 9 (depends on 8)

The method of claim 8, wherein a direction of the gas flow remains substantially constant during dispensing the liquid etchant.

### Claim 10 (depends on 8)

The method of claim 8, wherein removing the dummy gate stack further comprises:
turning the gas flow off after the dummy gate stack on the substrate is etched away by the liquid etchant.

### Claim 11 (depends on 8)

The method of claim 8, further comprising:
recessing the interlayer dielectric layer; and
forming a capping layer over the recessed interlayer dielectric layer prior to removing the dummy gate stack.

### Claim 12 (depends on 11)

The method of claim 11, wherein dispensing the liquid etchant onto the substrate is performed such that a top surface of the recessed interlayer dielectric layer is spaced apart from the liquid etchant by the capping layer.

### Claim 13 (depends on 8)

The method of claim 8, further comprising:
dispensing a cleaning agent onto the substrate after removing the dummy gate stack; and
blowing the cleaning agent on the substrate using the gas flow.

### Claim 14 (depends on 8)

The method of claim 8, wherein the substrate is free from rotation during dispensing the liquid etchant.

### Claim 15

A method, comprising:
forming a dummy gate stack over a substrate;
forming a plurality of gate spacers respectively on opposite sides of the dummy gate stack;
removing the dummy gate stack to form a gate trench between the gate spacers, wherein removing the dummy gate stack comprises:
dispensing a liquid etchant onto the substrate, wherein the substrate is free from rotation during dispensing the liquid etchant; and
blowing the liquid etchant on the substrate using a gas flow; and
forming a metal gate structure in the gate trench.

### Claim 16 (depends on 15)

The method of claim 15, wherein blowing the liquid etchant comprises ejecting the gas flow from a gas ejector at a first position not vertically overlapping the substrate.

### Claim 17 (depends on 16)

The method of claim 16, wherein blowing the liquid etchant further comprises
exhausting the gas flow through a gas extractor at a second position not vertically overlapping the substrate.

### Claim 18 (depends on 17)

The method of claim 17, wherein the first position is spaced apart from the second position along a direction substantially perpendicular to a longitudinal axis of the dummy gate stack.

### Claim 19 (depends on 15)

The method of claim 15, wherein the liquid etchant is dispensed through a plurality of dispensing holes on a showerhead.

### Claim 20 (depends on 19)

The method of claim 19, wherein the dispensing holes are substantially equidistantly arranged on the showerhead.