# US 12,216,412 B2 · Frequency-picked methodology for diffraction-based overlay measurement

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- Number: US 12,216,412 B2
- Document ID: US12216412B2
- Status: Granted
- Kind: B2
- Application number: 18/517,653
- Filed: 2023-11-22
- Published: 2024-03-14
- Granted: 2025-02-04
- Earliest claimed: 2020-02-27
- Assignees: Taiwan Semiconductor Manufacturing Company, Ltd.
- Applicants: Taiwan Semiconductor Manufacturing Company, Ltd.
- Inventors: Hung-Chih Hsieh; Ming-Hsiao Weng
- Web page: https://patentgrep.com/patent/US12216412B2

## CPC

- G03F 7/70633: {Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching}
- G03F 7/70625: {Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness}
- G03F 7/70683: {Mark designs}
- H10P 74/203: {Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects}
- 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

## Abstract

An overlay error measurement method includes disposing a lower-layer pattern over a substrate that includes disposing a first pattern having a first plurality of first sub-patterns extending in a first interval along a first direction and being arranged with a first pitch in a second direction crossing the first direction. The method includes disposing a second pattern having a second plurality of second sub-patterns extending in a second interval along the first direction and being arranged with a second pitch, smaller than the first pitch, in the second direction crossing the first direction. The second sub-patterns are disposed interleaved between the first sub-patterns. The method includes disposing an upper-layer pattern including a third pattern having the first pitch and at least partially overlapping with the lower-layer pattern over the lower-layer pattern and determining an overlay error between the lower-layer pattern and the upper-layer pattern.

## Claims

### Claim 1

A method, comprising:
disposing a first pattern over a substrate, the first pattern having a plurality of first sub-patterns extending in a first interval along a first direction and being arranged with a first pitch in a second direction crossing the first direction; and
disposing a second pattern over the substrate having a plurality of second sub-patterns disposed among the first sub-patterns and extending in a second interval along the first direction and being arranged with a second pitch different from the first pitch, in the second direction crossing the first direction;
disposing a third pattern over the first pattern, the third pattern having the first pitch and at least partially overlapping with the first pattern;
generating a first diffraction light associated with the first pitch at a first angle and a second diffraction light associated with the third pattern at the first angle;
generating a third diffraction light associated with the second pitch at a second angle, wherein the second angle is between 2 to 4 times larger than the first angle; and
determining an overlay error between the first pattern and the third pattern based on the first diffraction light and the second diffraction light.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first pitch is at least 3 times the second pitch, and wherein at least three second sub-patterns are distributed between each two neighboring first sub-patterns.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
detecting, by a detector, a combination of the first diffraction light and the second diffraction light; and
blocking the third diffraction light from the detector.

### Claim 4 (depends on 3)

The method of claim 3, wherein an aperture of the detector has a numerical aperture that blocks the third diffraction light.

### Claim 5 (depends on 3)

The method of claim 3, further comprising:
irradiating, with a coherent beam of light, at least a partial overlap of the third pattern and the first pattern to generate the first diffraction light, the second diffraction light, and the third diffraction light.

### Claim 6 (depends on 5)

The method of claim 5, further comprising:
generating the coherent beam of light by a laser light source.

### Claim 7 (depends on 1)

The method of claim 1, further comprising:
detecting a first signal, by one or more detectors, based on a combination of a first negative diffraction light and a second negative diffraction light;
detecting a second signal, by the one or more detectors, based on a combination of a first positive diffraction light and a second positive diffraction light;
combining the first signal and the second signal; and
determining the overlay error between the first pattern and the third pattern based on the combination of the first signal and the second signal.

### Claim 8

An overlay error measurement structure, comprising:
a first pattern disposed over a substrate; and
a second pattern disposed over the first pattern and at least partially overlapping with the first pattern, wherein:
the first pattern comprises a plurality of first sub-patterns extending in a first length along a first direction and being arranged with a first pitch in a second direction crossing the first direction and a plurality of second sub-patterns extending in a second length along the first direction and being arranged with a second pitch in the second direction crossing the first direction, wherein the second sub-patterns are disposed among the first sub-patterns, and wherein the second pitch is smaller than the first pitch to separate a first reflected light from the first pitch from a second reflected light from the second pitch; and
the second pattern comprises a plurality of third sub-patterns extending in the first direction and being arranged with the first pitch in the second direction.

### Claim 9 (depends on 8)

The overlay error measurement structure of claim 8, wherein
the first reflected light from the first pitch of the first pattern is configured to produce a first angle with a perpendicular plane to the substrate and the second reflected light from the second pitch of the first pattern is configured to make a second angle with the perpendicular plane to the substrate, and wherein the second angle is at least twice the first angle.

### Claim 10 (depends on 8)

The overlay error measurement structure of claim 8, wherein the first pitch is between 2 to 10 times the second pitch, wherein between 2 to 10 second sub-patterns are distributed in a first interval along the second direction between each two neighboring first sub-patterns, and wherein in each first interval one of the second sub-patterns is connected from either left or right of the second sub-pattern to a first sub-pattern.

### Claim 11 (depends on 8)

The overlay error measurement structure of claim 8, wherein the second pattern is disposed as a photo resist pattern.

### Claim 12 (depends on 8)

The overlay error measurement structure of claim 8, wherein each of first sub-patterns and each of the second sub-patterns have a same width.

### Claim 13 (depends on 8)

The overlay error measurement structure of claim 8, wherein the first and second directions are perpendicular to each other.

### Claim 14

A method comprising:
forming a first pattern having a plurality of first sub-patterns extending in a first interval along a first direction and being arranged with a first pitch in a second direction crossing the first direction; and
forming a second pattern having a plurality of second sub-patterns extending in a second interval along the first direction and being arranged with a second pitch, smaller than the first pitch, in the second direction crossing the first direction, wherein the second sub-patterns are disposed among the first sub-patterns; and
blocking a reflected first light associated with the second pitch from the second pattern;
forming a third pattern over the first pattern, the third pattern having the first pitch and at least partially overlapping with the first pattern; and
determining an overlay error between the first pattern and the third pattern based on diffracted light from the third pattern and diffracted light associated with the first pitch from the first pattern.

### Claim 15 (depends on 14)

The method of claim 14, wherein the first sub-patterns and the second sub-patterns produce an average distance between structures of the first and second patterns that is within a fifty percent range of a critical dimension (CD) of a semiconductor device.

### Claim 16 (depends on 14)

The method of claim 14, wherein the first interval and the second interval are same intervals and the first sub-patterns and the second sub-patterns are extended in parallel.

### Claim 17 (depends on 14)

The method of claim 14, wherein the determining the overlay error comprises:
applying a beam of light over a partial overlap of third pattern and the first pattern; and
analyzing a combination of diffracted light from the third pattern and diffracted light associated with the first pitch from the first pattern.

### Claim 18 (depends on 17)

The method of claim 17, wherein the analyzing the combination of diffracted light comprises determining an intensity difference between a combination of positive first order diffracted light and a combination of negative first order diffracted light.

### Claim 19 (depends on 17)

The method of claim 17, wherein the applying the beam of light further comprises:
irradiating, with a coherent beam of light a partial overlap of the third pattern and the first pattern.

### Claim 20 (depends on 19)

The method of claim 19, further comprising:
forming the first and second patterns over a substrate of a semiconductor device;
placing substrate on a stage; and
controlling a movement of the substrate under the coherent beam of light by a stage controller, wherein the coherent beam of light irradiates the partial overlap of the third pattern and the first pattern.