# US 12,000,693 B2 · Method of inspecting flatness of substrate

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- Number: US 12,000,693 B2
- Document ID: US12000693B2
- Status: Granted
- Kind: B2
- Application number: 17/689,371
- Filed: 2022-03-08
- Published: 2022-10-27
- Granted: 2024-06-04
- Earliest claimed: 2021-04-23
- Assignees: Darwin Precisions Corporation
- Applicants: Darwin Precisions Corporation
- Inventors: Chin-Wang Hsu; Wen-Yi Lin
- Web page: https://patentgrep.com/patent/US12000693B2

## CPC

- G01B 11/30: for measuring roughness or irregularity of surfaces
- G01B 11/306: {for measuring evenness}
- G01B 11/002: {for measuring two or more coordinates}
- H10P 72/0604: {Process monitoring, e.g. flow or thickness monitoring}
- H10P 72/0616: {Monitoring of warpages, curvatures, damages, defects or the like}
- Y02P 90/30: Computing systems specially adapted for manufacturing
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method of inspecting flatness of substrate is provided and includes providing a substrate. N first inspecting points are selected from the surface of the substrate along a first straight line, where the coordinate of the i-th first inspecting point is (Xi,Yi,Zi). By using a formula “D=Σi=1N−1√{square root over ((Xi+1−Xi)2+(Yi+1−Yi)2+(Zi+1−Zi)2)}”, a first measurement length D is calculated. By using a formula “F=(D−S)/S”, a first flatness index F is calculated. S is the horizontal distance between 1st first inspecting point and N-th first inspecting point. When the first flatness index F is larger than a first threshold, the substrate is determined to be unqualified.

## Claims

### Claim 1

A method of inspecting flatness of a substrate, comprising:
providing the substrate having a surface;
letting an optical dimension measuring device select N first inspecting points (Xi, Yi) from the surface along a first straight line in a X direction;
letting the optical dimension measuring device measure a plurality of heights Zi of the N first inspecting points;
by using a formula: D=Σi=1N−1√{square root over ((Xi−1−Xi)2+(Yi−1−Yi)2+(Zi−1−Zi)2)}, calculating a first measurement length D;
by using a formula: F=(D−S)/S, calculating a first flatness index F, wherein S is a horizontal distance between 1st first inspecting point and N-th first inspecting point along the first straight line; and
scrapping the substrate having the first flatness index F larger than a first threshold, determining that the substrate is unqualified.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
letting the optical dimension measuring device select M second inspecting points (Aj,Bj) from the surface along a second straight line in a Y direction perpendicular to the X direction;
letting the optical dimension measuring device measure a plurality of heights Cj of the M second inspecting points;
by using a formula: d=Σj=1M−1√{square root over ((Aj+1−Aj)2+(Bj+1−Bj)2+(Cj+1−Cj)2)}, calculating a second measurement length d;
by using a formula: f=(d−R)/R, calculating a second flatness index f, wherein R is a horizontal distance between 1st second inspecting point and M-th second inspecting point along the second straight line; and
scrapping the substrate having the second flatness index f larger than a second threshold, determining that the substrate is unqualified.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
identifying the substrate as being qualified when the first flatness index F is less than or equal to the first threshold, and the second flatness index f is less than or equal to the second threshold.

### Claim 4 (depends on 2)

The method of claim 2, wherein a length of the first straight line is longer than a length of the second straight line, and N>M.

### Claim 5 (depends on 2)

The method of claim 2, wherein each of the first threshold and the second threshold is 2.

### Claim 6 (depends on 1)

The method of claim 1, wherein a horizontal distance between adjacent two of the first inspecting points is less than or equal to 1 cm.