# US 9,006,867 B2 · Monitoring structure and monitoring method for silicon wet etching depth

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- Number: US 9,006,867 B2
- Document ID: US9006867B2
- Status: Granted
- Kind: B2
- Application number: 14/364,933
- Filed: 2012-11-20
- Published: 2014-11-27
- Granted: 2015-04-14
- Earliest claimed: 2011-12-13
- Assignees: Csmc Technologies Fabi Co., Ltd.
- Applicants: CSMC Technologies FAB1 Co., Ltd.
- Inventors: Xinwei Zhang; Changfeng Xia; Chengjian Fan; Wei Su
- Web page: https://patentgrep.com/patent/US9006867B2

## CPC

- H10P 74/27: {Structural arrangements therefor}
- H10P 50/644: {Anisotropic liquid etching (H10P50/61 takes precedence)}
- H10P 50/693: {characterised by their size, orientation, disposition, behaviour or shape, in horizontal or vertical plane}
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

A monitoring structure and a relevant monitoring method for the silicon wet etching depth are provided. The structure includes a wet etched groove formed on a monocrystalline silicon material with at least two top surfaces thereof being rectangular; and the top surface widths of the grooves are Wu and W1 respectively, Wu=du/0.71, and W1=du/0.71, where du is the maximum wet etching depth to be monitored, and d1 is the minimum of the wet etching depth to be monitored. The method includes: performing anisotropic wet etching on a monocrystalline silicon wafer according to a pattern with a monitoring pattern, forming an etched groove to be monitored and a structure for monitoring the depth of the groove, and then monitoring the structure to monitor the wet etching depth. The etching depth of the groove can be monitored with low costs, and a higher monitoring accuracy is obtained.

## Claims

### Claim 1

A structure of monitoring silicon wet etching depth, comprising:
at least two wet etching grooves defined on a monocrystalline silicon material, wherein etch top surface of the wet etching groove is rectangular, top surface widths of the at least two wet etching grooves are Wu and W1, respectively, Wu=du/0.71, W1=d1/0.71; wherein du is the maximum wet etching depth to be monitored, d1 is the minimum wet etching depth to be monitored.

### Claim 2 (depends on 1)

The structure of monitoring silicon wet etching depth according to claim 1, wherein an etching surface of the monocrystalline silicon material is a crystal face (100).

### Claim 3 (depends on 1)

The structure of monitoring silicon wet etching depth according to claim 1, wherein the number of the wet etching grooves is n, n>3.

### Claim 4 (depends on 3)

The structure of monitoring silicon wet etching depth according to claim 3, wherein the top surface widths of n wet etching grooves are greater than or equal to W1 and less than or equal to Wu.

### Claim 5 (depends on 4)

The structure of monitoring silicon wet etching depth according to claim 4, wherein the n wet etching grooves are arranged according to top surface widths in ascending order from W1 to Wu.

### Claim 6 (depends on 3)

The structure of monitoring silicon wet etching depth according to claim 3, wherein the n wet etching grooves are arranged closely.

### Claim 7

A mask plate having monitoring pattern of silicon wet etching depth, comprising a monitoring pattern, wherein the monitoring pattern comprises at least two rectangular windows for wet etching; widths of the at least two windows are Wu and W1, respectively; Wu=du/0.71, W1=d1/0.71; du is the maximum wet etching depth to be monitored, d1 is the minimum wet etching depth to be monitored.

### Claim 8 (depends on 7)

The mask plate having monitoring pattern of silicon wet etching depth according to claim 7, wherein the number of the windows is n, n>3.

### Claim 9 (depends on 8)

The mask plate having monitoring pattern of silicon wet etching depth according to claim 8, wherein widths of n windows are greater than or equal to W1 and less than or equal to Wu.

### Claim 10 (depends on 9)

The mask plate having monitoring pattern of silicon wet etching depth according to claim 9, wherein the n windows are arranged according to widths in ascending order from W1 to Wu.

### Claim 11 (depends on 8)

The mask plate having monitoring pattern of silicon wet etching depth according to claim 8, wherein the n windows are arranged closely.

### Claim 12

A method of monitoring silicon wet etching depth, comprising the steps of:
step one, adding a monitoring pattern to a layout, wherein the monitoring pattern comprises: at least two rectangular windows for wet etching; widths of the at least two windows are Wu and W1, respectively; Wu=du/0.71, W1=d1/0.71; du is the maximum wet etching depth to be monitored, d1 is the minimum wet etching depth to be monitored;
step two, anisotropic wet etching a monocrystalline silicon wafer according to the layout having the monitoring pattern, and forming an etching groove needed to be monitored and a monitoring structure configured to monitor a depth of the etching groove; in which, the monitoring structure is formed by etching according to the monitoring pattern, the monitoring structure comprises at least two wet etching grooves with top surface widths of Wu and W1, respectively;
step three, monitoring the monitoring structure in the step two or after the step two of wet etching, determining an actual etching depth range of the etching groove needed to be monitored according to a monitoring result, thus performing the monitoring of the wet etching depth;
wherein the step of determining the actual etching depth range of the etching groove needed to be monitored according to the monitoring result comprises:
when bottoms of the wet etching grooves with top surface widths of Wu and W1 are planar structures, then determining the actual etching depth dactual of the etching grooves needed to be monitored is less than d1;
when a bottom of the wet etching groove with the top surface width of Wu is a planar structure, while a bottom of the wet etching groove with the top surface width of W1 is a linear structure, then determining the actual etching depth dactual of the etching grooves needed to be monitored is greater than or equal to d1 and less than du; and
when bottoms of the wet etching grooves with top surface widths of Wu and W1 are linear structures, then determining the actual etching depth dactual of the etching grooves needed to be monitored is greater than or equal to du.

### Claim 13 (depends on 12)

The method of monitoring silicon wet etching depth according to claim 12, wherein the number of the windows in the monitoring pattern is n, n>3.

### Claim 14 (depends on 13)

The method of monitoring silicon wet etching depth according to claim 13, wherein widths of n windows are greater than or equal to W1 and less than or equal to Wu.

### Claim 15 (depends on 14)

The method of monitoring silicon wet etching depth according to claim 14, wherein the n windows are arranged according to widths in ascending order from W1 to Wu.

### Claim 16 (depends on 13)

The method of monitoring silicon wet etching depth according to claim 13, wherein the n windows are arranged closely.

### Claim 17 (depends on 13)

The method of monitoring silicon wet etching depth according to claim 13, wherein when the number of the windows in the monitoring pattern is n, n>3, if a bottom of the wet etching groove with a top surface width of Wx is a planar structure, while a bottom of the wet etching groove with a top surface width of Wy is a linear structure, then determining the actual etching depth dactual of the etching grooves needed to be monitored is greater than or equal to dy and less than dx; dx=0.71Wx, dy=0.71Wy.

### Claim 18 (depends on 12)

The method of monitoring silicon wet etching depth according to claim 12, wherein an etching surface of the monocrystalline silicon wafer is a crystal face (100).

### Claim 19 (depends on 12)

The method of monitoring silicon wet etching depth according to claim 12, wherein an anisotropic etchant is used in the wet etching with a rate on the silicon crystal face (100) faster than that on a silicon crystal face (111).

### Claim 20 (depends on 12)

The method of monitoring silicon wet etching depth according to claim 12, wherein a microscope is used to monitor the monitoring structure in the step three.