SUBSTRATE DEFECT INSPECTION METHOD, COMPUTER READABLE STORAGE MEDIUM, AND DEFECT INSPECTION APPARATUS

Abstract

In the present invention, data on a substrate image picked up by an image pickup unit is outputted to a difference calculation unit where a difference image from a normal substrate is calculated. A synthesis calculation unit calculates a synthesized image by rotating the difference image 360 degrees by every predetermined angle about the center of the substrate and synthesizing the images. A Zernike calculation unit digitizes the synthesized image by a Zernike polynomial and outputs a concentric circle component to a determination unit where the component is compared with a previously set threshold value, so that the presence or absence of a defect on the substrate is determined. The present invention can facilitate the determination of the presence or absence of a macro defect on the substrate and reduce the time required for the determination.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view showing a configuration of an inspection apparatus used in implementing an inspection method according to the present embodiment;

FIG. 2 is an explanatory view showing an image for each component after an image is decomposed into components using a Zernike polynomial;

FIG. 3 is a flowchart showing a processing procedure of the inspection method of the present embodiment;

FIG. 4 is an explanatory view showing an image obtained by picking up an image of a wafer being an inspection object using a CCD camera;

FIG. 5 is an explanatory view showing an image of a normal wafer;

FIG. 6 is an explanatory view showing a difference image between the image of the wafer being the inspection object in FIG. 4 and the image of the normal wafer in FIG. 5;

FIG. 7 is a synthesized image obtained by rotating the difference image in FIG. 6 and synthesizing the images;

FIG. 8 is a table showing Zernike values obtained using the Zernike polynomial for each component, for the image in FIG. 7;

FIG. 9 is an explanatory view showing an image obtained by picking up an image of a wafer being an inspection object using the CCD camera;

FIG. 10 is an explanatory view showing an image of a normal wafer;

FIG. 11 is an explanatory view showing a difference image between the image of the wafer being the inspection object in FIG. 9 and the image of the normal wafer in FIG. 10;

FIG. 12 is a synthesized image obtained by rotating the difference image in FIG. 11 and synthesizing the images; and

FIG. 13 is a table showing Zernike values obtained using the Zernike polynomial for each component, for the image in FIG. 12.

Claims

1. A method of inspecting a substrate for a defect, comprising the steps of: obtaining a difference image between an image of a normal substrate and an image of an inspection object;rotating the difference image 360 degrees by every predetermined angle about a center of the substrate, and synthesizing the difference image before the rotation and the difference image after the rotation so that each pixel value of the image after the synthesis is increased;digitizing using a Zernike polynomial the image obtained by the synthesis; anddetermining the presence or absence of a defect on the substrate based on a Zernike value of a concentric circle component out of Zernike values digitized by the Zernike polynomial.

2. The method as set forth in claim 1, wherein the predetermined angle is equal to or less than 10 degrees.

3. The method as set forth in claim 1, wherein the difference image is a color image, and the presence or absence of a defect on the substrate is determined based on the Zermike value of the concentric circle component of at least one of R, G, and B out of the Zernike values digitized by the Zernike polynomial.

4. The method as set forth in claim 1, wherein the difference image is a color image, and the presence or absence of a defect on the substrate is determined based on the Zernike values of the concentric circle components of all of R, G, and B out of the Zernike values digitized by the Zernike polynomial.

5. The method as set forth in claim 1, wherein the difference image is a monochrome image.

6. The method as set forth in claim 1, wherein the defect on the substrate is defocus during exposure processing.

7. The method as set forth in claim 1, wherein the defect on the substrate is uneven application of a resist formed on the substrate.

8. A computer readable storage medium storing a program for causing a computer to execute a substrate defect inspection method, said defect inspection method comprising the steps of:obtaining a difference image between an image of a normal substrate and an image of an inspection object;rotating the difference image 360 degrees by every predetermined angle about a center of the substrate, and synthesizing the difference image before the rotation and the difference image after the rotation so that each pixel value of the image after the synthesis is increased;digitizing using a Zernike polynomial the image obtained by the synthesis; anddetermining the presence or absence of a defect on the substrate based on a Zernike value of a concentric circle component out of Zernike values digitized by the Zernike polynomial.

9. A defect inspection apparatus for inspecting a substrate for a defect, comprising: a stage mounting the substrate thereon and movable in an X-direction and a Y-direction:an image pickup unit for picking up an image of the substrate on said stage;a difference calculation unit for calculating an absolute value of a difference between image data obtained by said image pickup unit and previously stored image data on a normal substrate, and outputting data on a difference image based on the difference absolute value;a synthesis calculation unit for rotating the difference image obtained by said difference calculation unit about a center of the substrate, and synthesizing the rotated difference images to obtain a synthesized image;a Zernike calculation unit for digitizing the synthesized image obtained by said synthesis calculation unit by a Zernike polynomial; anda determination unit for comparing data outputted from said Zernike calculation unit with a previously set threshold value.

10. The defect inspection apparatus as set forth in claim 9, wherein the difference image is a color image, andwherein said determination unit compares a Zernike value of a concentric circle component of at least one of R, G, and B out of the Zernike values digitized by said Zernike calculation unit, with a previously set threshold value.

11. The defect inspection apparatus as set forth in claim 9, wherein the difference image is a color image, andwherein said determination unit compares Zernike values of concentric circle components of all of R, G, and B out of the Zernike values digitized by said Zernike calculation unit, with previously set threshold values.