# US 12,759,107 B2 · Generation of background signal sequence using an in-situ monitoring system in chemical mechanical polishing

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- Number: US 12,759,107 B2
- Document ID: US12759107B2
- Status: Granted
- Kind: B2
- Application number: 18/582,553
- Filed: 2024-02-20
- Published: 2025-08-21
- Granted: 2026-10-13
- Earliest claimed: 2024-02-20
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Kun Xu; Jimin Zhang; Chen-Wei Chang; Haosheng Wu; Patrick A. Higashi; Jianshe Tang
- Web page: https://patentgrep.com/patent/US12759107B2

## CPC

- B24B 37/013: Devices or means for detecting lapping completion
- B24B: MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING (grinding of gear teeth B23F, of screw-threads B23G1/36; by electro-erosion B23H; abrasive or related blasting B24C; tools for grinding, buffing or sharpening B24D; polishing compositions C09G1/00; abrasives C09K3/14; electrolytic etching or polishing C25F3/00; grinding arrangements for use on assembled railway tracks E01B31/17); DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS

## Abstract

A polishing control technique includes storing data representing a sequence of background traces generated by a sequence of scans of a sensor of an in-situ monitoring system across a substrate, and polishing a layer on a substrate. The layer is monitored during the polishing with the in-situ monitoring system, including repeatedly sweeping the sensor of the in-situ monitoring system across substrate such that each sweep provides a measured trace. For each measured trace, a respective background trace that has an equivalent position in the sequence of background traces is subtracted from the measured trace to generate a modified trace, and a sequence of estimated thickness values is generated based on the modified traces. A polishing endpoint is detected or a polishing parameter is modified based on the sequence of estimated thickness values.

## Claims

### Claim 1

A method of generating a sequence of reference traces for use in in-situ monitoring, the method comprising:
measuring an angular orientation of a calibration substrate;
rotating a carrier head holding the calibration substrate to a first predetermined angular position based on the measured angular orientation;
rotating a platen to a second predetermined angular position;
bringing the calibration substrate into contact with a polishing pad on the platen with calibration substrate at the first predetermined angular position and the platen at the second predetermined angular position;
rotating the platen and the carrier head with the calibration substrate in contact with the polishing pad;
monitoring the calibration substrate by sweeping a sensor of an in-situ monitoring system across the calibration substrate to generate a sequence of reference traces with each respective reference trace of the sequence of reference traces corresponding to a respective sweep of a sequence of sweeps by the sensor, and wherein each reference trace includes a series of signal values; and
storing the sequence of reference traces and labelling each reference trace to distinguish an order of the reference traces within the sequence.

### Claim 2 (depends on 1)

The method of claim 1, comprising conducting the monitoring of the calibration substrate with substantially no polishing occurring.

### Claim 3 (depends on 2)

The method of claim 2, comprising flushing a polishing surface of the polishing pad with a cleaning liquid to remove slurry from the polishing surface before bringing the calibration substrate into contact with a polishing pad.

### Claim 4 (depends on 2)

The method of claim 2, comprising venting a chamber in the carrier head holding the calibration substrate while the calibration substrate is in contact with the polishing pad.

### Claim 5 (depends on 1)

The method of claim 1, wherein the in-situ monitoring system comprises an eddy current monitoring system.

### Claim 6 (depends on 5)

The method of claim 5, wherein scanning the scanning the sensor across the calibration substrate generates a raw signal trace, and comprising converting the raw signal trace to the reference trace using a correlation curve.

### Claim 7 (depends on 6)

The method of claim 6, wherein the correlation curve is calibrated to convert raw signal values to thickness values for a conductive layer, and the calibration substrate is not covered by the conductive layer.

### Claim 8 (depends on 6)

The method of claim 6, wherein converting the raw signal trace to the reference trace using the correlation curve generates a preliminary reference trace, and comprising performing edge reconstruction on each preliminary reference trace to generate the reference trace.

### Claim 9 (depends on 8)

The method of claim 8, wherein performing edge reconstruction includes including processing portions of the preliminary trace corresponding to an edge of the calibration substrate through a neural network.

### Claim 10 (depends on 1)

The method of claim 1, comprising counting a number of rotations of the platen to provide an ordinal position of the reference trace in the sequence of reference traces and labelling the reference trace with ordinal position.

### Claim 11 (depends on 1)

The method of claim 1, comprising scaling the reference traces such that each reference trace extends from a same start time or position to a same end time or position.

### Claim 12 (depends on 11)

The method of claim 11, comprising detecting a leading edge of the reference trace and a trailing edge of the reference trace.

### Claim 13 (depends on 1)

The method of claim 1, comprising fabricating the calibration substrate by depositing an outer conductive layer over one or more underlying layers below the outer conductive layer, and polishing the outer conductive layer until an underlying layer from the one or more underlying layers is exposed, such that the reference traces are background traces resulting from monitoring of a substrate that is not covered by the outer conductive layer.

### Claim 14 (depends on 1)

The method of claim 1, comprising fabricating the calibration substrate by depositing one or more underlying layers on a substrate, and generating the sequence of reference trace before depositing an outer conductive layer on the one or more underlying layers.

### Claim 15

A computer program product computer program product residing on a non-transitory computer readable medium and comprising instructions for causing one or more computers to:
receive a measurement of an angular orientation of a calibration substrate;
cause a carrier head holding the calibration substrate to rotate to a first predetermined angular position based on the measured angular orientation;
cause a platen to rotate a second predetermined angular position;
cause the calibration substrate to be brought into contact with a polishing pad on the platen with calibration substrate at the first predetermined angular position and the platen at the second predetermined angular position;
cause the platen and the carrier head to rotate with the calibration substrate in contact with the polishing pad;
receive a sequence of reference traces from an in-situ monitoring system with each respective reference trace of the sequence of reference traces corresponding to a respective sweep of a sequence of sweeps by a sensor of the in-situ monitoring system across the calibration substrate, and wherein each reference trace includes a series of signal values; and
store the sequence of reference traces and labelling each reference trace to distinguish an order of the reference traces within the sequence.

### Claim 16 (depends on 15)

The computer program product of claim 15, comprising instructions to cause a polishing surface of the polishing pad to be flushed with a cleaning liquid to remove slurry from the polishing surface before bringing the calibration substrate into contact with a polishing pad.

### Claim 17 (depends on 15)

The computer program product of claim 15, comprising instructions to cause a chamber in a carrier head holding the calibration substrate to be vented while the calibration substrate is in contact with the polishing pad.

### Claim 18 (depends on 15)

The computer program product of claim 15, comprising instructions count a number of rotations of the platen to provide an ordinal position of the reference trace in the sequence of reference traces and labelling the reference trace with ordinal position.

### Claim 19 (depends on 15)

The computer program product of claim 15, comprising instructions to convert a raw signal trace from the sensor to a preliminary reference trace using a correlation curve.

### Claim 20 (depends on 19)

The computer program product of claim 19, comprising instructions to perform edge reconstruction on the preliminary reference trace to generate the reference trace.