# US 10,373,818 B1 · Method of wafer recycling

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- Number: US 10,373,818 B1
- Document ID: US10373818B1
- Status: Granted
- Kind: B1
- Application number: 15/885,311
- Filed: 2018-01-31
- Published: 2019-08-01
- Granted: 2019-08-06
- Earliest claimed: 2018-01-31
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Co., Ltd.
- Inventors: Yi-Hua Cheng; Yen-Hsun Wu
- Web page: https://patentgrep.com/patent/US10373818B1

## CPC

- H10P 90/16: {by reclaiming or re-processing}
- C23C 16/00: Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes (reactive sputtering or vacuum evaporation C23C14/00)
- C23C 16/405: {of refractory metals or yttrium}
- C23C 16/52: Controlling or regulating the coating process {(C23C16/45557, C23C16/279 take precedence)}
- H10P 14/6339: {deposition by cyclic CVD, e.g. ALD, ALE or pulsed CVD}
- H10P 14/693: {the material containing hafnium, e.g. HfSiOx or HfSiON}
- H10P 50/283: {by chemical means}
- H10P 52/402: {of semiconductor materials}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

Methods are provided for recycling a dummy wafer so that the dummy wafer may be repeatedly used in a deposition process. The dummy wafer includes a substrate and an oxide layer on the substrate that is formed by the deposition process. A thickness of the oxide layer on the dummy wafer may be measured, and the dummy wafer may be subjected to recycling depending on whether the measured thickness of the oxide layer exceeds a threshold thickness. The dummy wafer is recycled by removing the oxide layer, which may be accomplished by performing an etching process. A mechanical polishing process may be performed to smooth the surface of the substrate. The dummy wafer may then be reused in a subsequent deposition process.

## Claims

### Claim 1

A wafer processing method, comprising:
receiving a wafer, the wafer including a substrate and a first oxide layer over the substrate;
determining whether a thickness of the first oxide layer exceeds a threshold thickness;
performing an etching process to remove the first oxide layer in response to determining the thickness of the first oxide layer exceeds the threshold thickness;
performing a mechanical polishing process on the wafer; and
reusing the wafer in a semiconductor process.

### Claim 2 (depends on 1)

The method of claim 1 wherein the reusing the wafer in a semiconductor process includes reusing the wafer in an oxide deposition process.

### Claim 3 (depends on 1)

The method of claim 1 wherein the threshold thickness is within a range from 400 nm to 1000 nm, inclusive.

### Claim 4 (depends on 1)

The method of claim 1 wherein the wafer is a dummy wafer.

### Claim 5 (depends on 1)

The method of claim 1 wherein the etching process utilizes hydrofluoric acid as an etchant.

### Claim 6 (depends on 5)

The method of claim 5 wherein the etchant comprises a 49% hydrofluoric acid solution.

### Claim 7 (depends on 1)

The method of claim 1 wherein the first oxide layer is a hafnium oxide (HfO2) layer.

### Claim 8 (depends on 1)

The method of claim 1 wherein the performing the mechanical polishing process includes performing chemical-mechanical planarization.

### Claim 9 (depends on 8)

The method of claim 8 wherein the performing the chemical-mechanical planarization includes removing a portion of the substrate, a thickness of the removed portion of the substrate being within a range from 0.5 μm to 1 μm, inclusive.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
depositing a second oxide layer on the first oxide layer in response to determining the thickness of the first oxide layer is less than the threshold thickness;
determining whether a combined thickness of the first and the second oxide layers exceeds the threshold thickness; and
performing the etching process to remove the first and the second oxide layers in response to determining the combined thickness of the first and the second oxide layers exceeds the threshold thickness.

### Claim 11

A method, comprising:
depositing hafnium oxide (HfO2) on a first batch of semiconductor wafers, the first batch of semiconductor wafers including a first production wafer, a first particle control wafer, and a dummy wafer;
removing the deposited hafnium oxide from the dummy wafer by etching the dummy wafer with a hydrofluoric acid solution; and
polishing the dummy wafer by chemical-mechanical planarization.

### Claim 12 (depends on 11)

The method of claim 11, further comprising:
depositing hafnium oxide on a second batch of semiconductor wafers, the second batch of semiconductor wafers including a second production wafer, a second particle control wafer, and the dummy wafer.

### Claim 13 (depends on 11)

The method of claim 11, further comprising:
measuring a thickness of the hafnium oxide layer on the dummy wafer; and
determining whether the measured thickness of the hafnium oxide layer exceeds a threshold thickness,
wherein the removing the deposited hafnium oxide from the dummy wafer is performed in response to determining the measured thickness of the hafnium oxide layer exceeds the threshold thickness.

### Claim 14 (depends on 11)

The method of claim 11, further comprising:
inspecting a surface of the dummy wafer, subsequent to the polishing the dummy wafer by chemical-mechanical planarization, to determine whether defects are present on the surface of the dummy wafer; and
in response to determining defects are present on the surface of the dummy wafer:
etching the dummy wafer with the hydrofluoric acid solution; and
polishing the dummy wafer by the chemical-mechanical planarization.

### Claim 15 (depends on 11)

The method of claim 11 wherein the hydrofluoric acid solution is a 49% hydrofluoric acid solution.

### Claim 16 (depends on 15)

The method of claim 15 wherein etching the dummy wafer with the hydrofluoric acid solution includes etching the dummy wafer for an etch time of at least 40 minutes.

### Claim 17

A method, comprising:
depositing hafnium oxide (HfO2) on a first batch of semiconductor wafers, the first batch of semiconductor wafers including a first plurality of production wafers, a first particle control wafer, and a dummy wafer;
measuring a thickness of a first hafnium oxide layer on the dummy wafer;
determining whether the measured thickness of the first hafnium oxide layer exceeds a threshold thickness;
in response to determining that the measured thickness of the first hafnium oxide layer is less than the threshold thickness, reusing the dummy wafer by depositing hafnium oxide on a second batch of semiconductor wafers, the second batch of semiconductor wafers including a second plurality of production wafers, a second particle control wafer, and the dummy wafer;
measuring a thickness of a second hafnium oxide layer on the dummy wafer, the thickness of the second hafnium oxide layer including the thickness of the first hafnium oxide layer;
determining whether the measured thickness of the second hafnium oxide layer exceeds the threshold thickness;
in response to determining that the measured thickness of the second hafnium oxide layer exceeds the threshold thickness, removing the second hafnium oxide layer from the dummy wafer by etching the dummy wafer with a hydrofluoric acid solution; and
polishing the dummy wafer by chemical-mechanical planarization.

### Claim 18 (depends on 17)

The method of claim 17 wherein the hydrofluoric acid solution is a 49% hydrofluoric acid solution.

### Claim 19 (depends on 18)

The method of claim 18 wherein the etching the dummy wafer with the hydrofluoric acid solution includes etching the dummy wafer for an etch time of at least 40 minutes.

### Claim 20 (depends on 17)

The method of claim 17 wherein the polishing the dummy wafer includes removing a portion of the dummy wafer, a thickness of the removed portion of the dummy wafer being within a range from 0.5 μm to 1 μm, inclusive.