# US 2020/0401041 A1 · Chemical Composition for Tri-Layer Removal

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- Number: US 2020/0401041 A1
- Document ID: US20200401041A1
- Status: Published application
- Kind: A1
- Application number: 17/007,733
- Filed: 2020-08-31
- Published: 2020-12-24
- Earliest claimed: 2017-08-30
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Li-Min Chen; Kuo Bin Huang; Neng-Jye Yang; Chia-Wei Wu; Jian-Jou Lian
- Web page: https://patentgrep.com/patent/US20200401041A1

## CPC

- G03F 7/0035: {Multiple processes, e.g. applying a further resist layer on an already in a previously step, processed pattern or textured surface}
- G03F 1/80: Etching
- G03F 7/0002: {Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping}
- G03F 7/0757: {Macromolecular compounds containing Si-O, Si-C or Si-N bonds (G03F7/0752 takes precedence)}
- G03F 7/094: {Multilayer resist systems, e.g. planarising layers}
- G03F 7/16: Coating processes; Apparatus therefor (applying coatings to base materials in general B05; applying photosensitive compositions to base for photographic purposes G03C1/74)
- G03F 7/2002: {with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image}
- G03F 7/425: {containing mineral alkaline compounds; containing organic basic compounds, e.g. quaternary ammonium compounds; containing heterocyclic basic compounds containing nitrogen}
- H10P 14/6903: {containing silicon}
- H10P 50/283: {by chemical means}
- H10P 50/287: {by chemical means}
- H10P 76/2041: {Photolithographic processes}
- H10P 76/405: {characterised by their composition, e.g. multilayer masks}
- H10P 76/4085: {characterised by the processes involved to create the masks}
- H10W 20/01: {Manufacture or treatment}
- H10W 20/089: {using processes for implementing desired shapes or dispositions of the openings, e.g. double patterning}
- H10W 20/087: {involving multiple stacked pre-patterned masks}
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method includes forming a tri-layer. The tri-layer includes a bottom layer; a middle layer over the bottom layer; and a top layer over the middle layer. The top layer includes a photo resist. The method further includes removing the top layer; and removing the middle layer using a chemical solution. The chemical solution is free from potassium hydroxide (KOH), and includes at least one of a quaternary ammonium hydroxide and a quaternary ammonium fluoride.

## Claims

### Claim 1

A method comprising:
forming a tri-layer, the tri-layer comprising:
a bottom layer, wherein the bottom layer is formed of a cross-linked material;
a first middle layer over the bottom layer; and
a first top layer over the first middle layer, wherein the first top layer comprises a photo resist;
performing a light-exposure process on the first top layer using a first photo lithography mask;
after the light-exposure process, removing the first top layer;
after the first top layer is removed, removing the first middle layer using a chemical solution;
forming a second middle layer over and in physical contact with the bottom layer; and
forming a second top layer over the second middle layer, wherein the second top layer comprises an additional photo resist.

### Claim 2 (depends on 1)

The method of claim 1, wherein entireties of the first top layer and the first middle layer are removed before the second middle layer is formed, and at a time the first middle layer has been removed, the bottom layer is a blanket layer.

### Claim 3 (depends on 1)

The method of claim 1 further comprising performing an additional light-exposure process on the second top layer using a second photo lithography mask having a same pattern as the first photo lithography mask.

### Claim 4 (depends on 3)

The method of claim 3, wherein the first photo lithography mask and the second photo lithography mask are a same photo lithography mask.

### Claim 5 (depends on 1)

The method of claim 1, wherein in the removing the first middle layer, an etching selectivity of a first etching rate of the first middle layer to a second etching rate of the bottom layer is greater than about 100.

### Claim 6 (depends on 1)

The method of claim 1, wherein the chemical solution is free from potassium hydroxide (KOH), and comprises at least one of a quaternary ammonium hydroxide and a quaternary ammonium fluoride.

### Claim 7 (depends on 6)

The method of claim 6, wherein the quaternary ammonium hydroxide comprises tetramethylammonium hydroxide (TMAH), and the quaternary ammonium fluoride comprises tetramethylammonium fluoride (TMAF).

### Claim 8 (depends on 7)

The method of claim 7, wherein a ratio of a first weight percentage of the TMAH to a second weight percentage of the TMAF is close to 1:3.

### Claim 9 (depends on 6)

The method of claim 6, wherein the chemical solution further comprises an organic solvent and water.

### Claim 10 (depends on 1)

The method of claim 1, wherein the second top layer is formed as a blanket layer.

### Claim 11

A method comprising:
forming a first middle layer over a bottom layer;
forming a first photo resist over the first middle layer;
patterning the first photo resist using a first photo lithography mask;
performing an inspection on the first photo resist;
after the inspection, removing entireties of the first photo resist and the first middle layer through wet etching processes, wherein at least a portion of the bottom layer remains;
forming a second middle layer comprising siloxane over the portion of the bottom layer;
forming a second photo resist over the second middle layer;
patterning the second photo resist using a second photo lithography mask, wherein the second photo lithography mask has an identical pattern as the first photo lithography mask;
transferring patterns in the second photo resist into the second middle layer and the bottom layer; and
transferring the patterns into a target layer underlying the bottom layer.

### Claim 12 (depends on 11)

The method of claim 11 further comprising patterning the second middle layer using the second photo resist as an etching mask.

### Claim 13 (depends on 11)

The method of claim 11, wherein at a time after the first middle layer is removed, the bottom layer remains as a blanket layer.

### Claim 14 (depends on 11)

The method of claim 11, wherein the bottom layer comprises a homogenous organic material that is cross-linked.

### Claim 15 (depends on 11)

The method of claim 11, wherein the first middle layer is removed in a wet etching process using a chemical solution comprising:
a quaternary ammonium hydroxide;
a quaternary ammonium fluoride; and
an organic solvent comprising ethylene glycol.

### Claim 16

A method comprising:
forming a bottom layer, wherein the bottom layer is formed of a cross-linked organic material;
forming a first middle layer over the bottom layer;
forming a first top layer over the first middle layer;
performing a first light-exposure process and a first development process on the first top layer;
removing the first top layer without transferring patterns in the first top layer into the first middle layer;
removing an entirety of the first middle layer using a chemical solution comprising quaternary ammonium hydroxide and a quaternary ammonium fluoride, wherein after the first middle layer is removed, the bottom layer is exposed to the chemical solution;
forming a second middle layer over and contacting the bottom layer;
forming a second top layer; and
performing an second light-exposure process and a second development process on the second top layer.

### Claim 17 (depends on 16)

The method of claim 16, wherein the first light-exposure process and the second light-exposure process are performed using photo lithography masks having an identical pattern.

### Claim 18 (depends on 16)

The method of claim 16 further comprising transferring patterns in the second middle layer and the bottom layer into an underlying low-k dielectric layer.

### Claim 19 (depends on 16)

The method of claim 16, wherein at a time the second middle layer is formed, the bottom layer is a blanket layer.

### Claim 20 (depends on 16)

The method of claim 16, wherein the chemical solution is free from potassium hydroxide (KOH).