TW202305345A - A wafer defect detection method and system thereof - Google Patents

Abstract

The present application relates to a wafer defect detection method and system, in which the surface image and internal image of the wafer to be detected are obtained in the self inspection area; The defect areas of the two groups were compared; When the surface image area at the same position is larger than the internal image area, it is determined as surface defect, when there is only internal or external image defect area, it is determined as single defect, and when there are different position defect areas in surface image and internal image, it is determined as surface defect and internal defect. The application further determines that the defects are surface defects and internal defects by comparing the area and clarity of the defects in the image, and carries out the secondary discrimination of the defect shape for the surface defects. With the help of re detection, the defect judgment can be more accurate, and the accurate wafer qualified or unqualified structure can be obtained, which greatly improves the yield of wafer production.

Description

Wafer defect detection method and system

The present application relates to the technical field of product inspection, in particular to a wafer defect inspection method and system.

Wafer refers to the silicon wafer used to make silicon semiconductor circuits, and its raw material is silicon. High-purity polysilicon is dissolved and mixed with silicon crystal seeds, and then slowly pulled out to form cylindrical single-crystal silicon. After the silicon ingot is ground, polished, and sliced, it forms a silicon wafer, that is, a wafer. At present, domestic wafer production lines are mainly 8-inch and 12-inch. The main processing methods of wafers are sheet processing and batch processing, that is, one or more wafers are processed at the same time. As semiconductor feature sizes become smaller and processing and measurement equipment become more advanced, new data characteristics emerge in wafer processing.

However, wafer peeling may occur during wafer dicing, wafer peeling and craters may occur during wiring, and cracks and peeling may occur in wafer testing after mold sealing. question. The defects formed on the wafer by these problems are often too subtle to be detected by traditional inspection. However, if the defective wafers continue to be installed in the subsequent process, it will only cause waste of cost and manpower, and reduce production quality. Therefore, this paper proposes a wafer defect detection method and system to solve it.

Aiming at the deficiencies of the prior art, the present application discloses a wafer defect detection method and system, which are used to solve the problem that the defects formed on the wafer are often too fine to be detected by traditional detection. However, if the defective wafers continue to be loaded in the subsequent process, it will only cause waste of cost and manpower, and reduce the production yield.

The application is realized through the following technical solutions:

A method for detecting wafer defects proposed by the present application, the steps of which include:

Obtain the surface image and internal image of the wafer to be inspected in the self-inspection area;

Compare the defect areas of the two groups of images;

And when the surface image area at the same position is larger than the internal image area, it is determined as a surface defect; when there is only an internal or external image defect area, it is determined as a single defect; when there are different position defect areas in the surface image and internal image For surface defects and internal defects.

Wherein, the self-inspection area is provided with a focusing camera, wherein the focusing camera automatically focuses on the wafer to be inspected to obtain its surface image and internal image.

Wherein, the focus camera is integrated with a CCD camera for acquiring images of the wafer surface and an IR camera for acquiring images inside the wafer.

Among them, when the area of the surface image is larger than the area of the internal image at the same position, and the definition is higher than that of the internal image, it is determined to be a surface defect.

Among them, when there is only an internal image defect area and no external image defect area, it is determined as an internal defect.

Among them, when there is only an external image defect area and no internal image defect area, it is determined as an external defect.

Among them, when the area of the surface image at the same position is equal to the area of the internal image, it is determined as a surface defect and an internal defect.

Wherein, when it is determined to be a surface defect and the defect area is granular, a blowing system is used to perform dust blowing treatment on the defect area of the wafer.

Wherein, the wafer after the dust blowing process is re-inspected, if there is still a granular surface defect area, it is judged as unqualified, and if there is no granular surface defect area, it is judged as qualified.

Among them, if it is determined to be a surface defect and the defect area is strip-shaped, rectangular, or other polygonal shapes with a large area, it will be directly judged as unqualified without re-inspection.

Among them, when there is an internal image defect area, it is directly judged as unqualified.

Wherein, the method judges that the detection is qualified includes one or more of the following: there is no surface defect and internal defect, or there is no internal defect and there is a surface defect, and the area of the surface defect does not exist after dust blowing treatment.

Another wafer defect detection system proposed by the present application includes

CCD camera for acquiring wafer surface images;

IR camera for obtaining images inside the wafer;

The focusing camera is used to integrate the CCD camera and the IR camera, and automatically focus on the wafer to be inspected in the self-inspection area to obtain its surface image and internal image.

Wherein, the CCD camera focuses the image of the wafer to be inspected onto the CCD wafer through the lens, and accumulates a corresponding proportion of charges according to the intensity of the light. Under the control of the sequence, it is moved point by point, and after filtering and amplification processing, an image signal output that is the same as the image of the wafer to be inspected is formed.

Wherein, the focus camera is provided with electronic contacts for exchanging various parameters with the camera body, and a ROM chip for storing lens focal length, maximum and minimum aperture or minimum focus distance parameters is set in the lens, and is set by setting parameters corresponding way of working.

The beneficial effect of this application is:

This application uses the focusing camera integrated with the CCD camera and the IR camera respectively or the surface and internal images of the wafer, and compares the area and clarity of the defect in the image to further determine whether it is a surface defect or an internal defect. The second judgment of the defect shape can be more accurately judged by re-inspection, and the accurate wafer structure can be obtained or failed, which greatly improves the production yield of the wafer.

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description are only the present invention For some embodiments of the application, those skilled in the art can also obtain other drawings based on these drawings without creative work.

[Fig. 1] is a flowchart of a wafer defect detection method;

[Figure 2] is a schematic diagram of the structure of a wafer defect detection system;

[Fig. 3] is a diagram of the first case of judging surface defects in the embodiment of the present application;

[Fig. 4] is a diagram of the second case of judging surface defects in the embodiment of the present application;

[Fig. 5] is a diagram of judging internal defects in the embodiment of the present application;

[Fig. 6] is a diagram of the first case of judging surface defects and internal defects in the embodiment of the present application;

[Fig. 7] is a diagram of the second case of judging surface defects and internal defects in the embodiment of the present application.

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

In Fig. 1, the flow chart of a kind of wafer defect detection method provided by the present application, its steps include:

Obtain the surface image and internal image of the wafer to be inspected in the self-inspection area;

Compare the defect areas of the two sets of images;

And when the surface image area at the same position is larger than the internal image area, it is determined as a surface defect; when there is only an internal or external image defect area, it is determined as a single defect; when there are different position defect areas in the surface image and internal image For surface defects and internal defects.

In one embodiment, a focusing camera is provided on the self-inspection area, wherein the focusing camera automatically focuses on the wafer to be inspected to obtain its surface image and internal image. The self-inspection area is a self-defined self-inspection area, which is used for detection outside the inspection area.

In one embodiment, the focusing camera is integrated with a CCD camera for capturing images of the wafer surface and an IR camera for capturing images inside the wafer.

In one embodiment, as shown in FIG. 3 , when the area of the surface image at the same position is larger than the area of the internal image, and the definition is higher than that of the internal image, it is determined to be a surface defect.

In one embodiment, as shown in FIG. 5 , when there is only an internal image defect area and no external image defect area, it is determined as an internal defect.

In one embodiment, as shown in FIG. 4 , when there is only an external image defect area and no internal image defect area, it is determined as an external defect.

In one embodiment, as shown in FIG. 6 , when the area of the surface image at the same position is equal to the area of the internal image, it is determined as a surface defect and an internal defect.

In one embodiment, as shown in Figure 7, when there are different defect areas in the surface image and the internal image, it is determined as a surface defect and an internal defect

In one embodiment, when it is determined to be a surface defect and the defect area is granular, a blowing system is used to perform dust blowing treatment on the defect area of the wafer. The wafer after dust blowing treatment is re-inspected. If there is still a granular surface defect area, it is judged as unqualified. If there is no granular surface defect area, it is judged as qualified.

In one embodiment, when it is determined to be a surface defect and the area of the defect is strip-shaped, rectangular, or other polygonal shapes with a large area, it is directly determined as unqualified without re-inspection.

In one embodiment, when there is an internal image defect area, it is directly determined as unqualified.

In one embodiment, the application judges that the detection is qualified includes one or more of the following: there is no surface defect and internal defect, or there is no internal defect and there is a surface defect, and the area of the surface defect does not exist after dust blowing treatment.

In Fig. 2, a kind of wafer defect inspection system provided by the present application includes a CCD camera for acquiring wafer surface images; an IR camera for acquiring wafer internal images; a focusing camera for integrating the CCD camera and IR camera, and automatically focus on the wafer to be inspected in the self-inspection area to obtain its surface image and internal image.

In one embodiment, the CCD camera focuses the image of the wafer to be inspected onto the CCD wafer through the lens, and accumulates a corresponding proportion of charge according to the intensity of light, and the charge accumulated by each pixel Under the control of the video sequence, it moves outward point by point, and after filtering and amplification processing, the image signal output identical to the image of the wafer to be inspected is formed.

In one embodiment, the CCD chip is made of a high-sensitivity semiconductor material, which can convert light into electric charge, and convert it into a digital signal through an analog-to-digital converter chip, and the digital signal is compressed by the flash memory inside the camera. Or built-in hard disk storage.

In one embodiment, the CCD chip is composed of many photosensitive units. When the surface of the CCD is irradiated by light, each photosensitive unit will reflect the charge on the component, and the signals generated by all photosensitive units are added together to form a picture. complete picture.

In one embodiment, an array of mos (metal-oxide-semiconductor) capacitors arranged according to certain rules is formed, and a thin layer (about 120nm) of silicon dioxide is grown on a p-type or n-type silicon substrate, and then Metal or doped polysilicon electrodes (gates) are sequentially deposited on the silicon dioxide thin layer to form a regular MOS capacitor array, and the input and output diodes at both ends constitute the CCD chip.

In one embodiment, the focus camera is provided with electronic contacts for exchanging various parameters with the body, and a ROM chip for storing lens focal length, maximum and minimum aperture or minimum focus distance parameters is set in the lens, and by setting parameters Set the corresponding working mode.

In one embodiment, the focusing camera utilizes the principle of object light reflection, and the reflected light is received by a sensor on the camera, and processed by a computer to drive an electric focusing device to focus.

In one embodiment, the focus camera is amplified by a pre-amplification circuit, and then processed and adjusted by various circuits, and the final standard signal can be sent to a recording medium such as a video recorder for recording, or transmitted through a communication system or sent to a monitoring displayed on the device.

To sum up, this application uses the focus camera integrated with the CCD camera and the IR camera respectively or the surface and internal images of the wafer, and further confirms the defect area and clarity by comparing the images. Surface defects and internal defects are determined, and the second judgment of the defect shape is carried out for the surface defects. With the help of re-inspection, the defect judgment can be obtained more accurately, and the accurate wafer qualified or unqualified structure can be obtained, which greatly improves the production quality of the wafer. Rate.

The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still apply to the foregoing embodiments Modifications are made to the recorded technical solutions, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims (15)

A wafer defect detection method, the steps comprising: Obtain the surface image and internal image of the wafer to be inspected in the self-inspection area; Compare the defect areas of the two sets of images; And when the surface image area at the same position is larger than the internal image area, it is determined as a surface defect; when there is only an internal or external image defect area, it is determined as a single defect; when there are different position defect areas in the surface image and internal image For surface defects and internal defects. A wafer defect inspection method according to claim 1, wherein a focusing camera is provided on the self-inspection area, wherein the focusing camera automatically focuses on the wafer to be inspected to obtain its surface image and internal image. A wafer defect detection method according to claim 2, wherein the focus camera is integrated with a CCD camera for acquiring images of the wafer surface and an IR camera for acquiring images inside the wafer. A wafer defect detection method according to Claim 1, wherein, at the same position, when the area of the surface image is larger than the area of the internal image, and the definition is higher than that of the internal image, it is determined to be a surface defect. A wafer defect detection method according to Claim 1, wherein, when there is only an internal image defect area and no external image defect area, it is determined to be an internal defect. A wafer defect detection method according to claim 1, wherein, when there is only an external image defect area and no internal image defect area, it is determined as an external defect. A wafer defect detection method according to Claim 1, wherein, when the area of the surface image at the same position is equal to the area of the internal image, it is determined as a surface defect and an internal defect. A wafer defect detection method as described in Claim 1, wherein, when it is determined to be a surface defect and the defect area is granular, a blowing system is used to perform dust blowing treatment on the defect area of the wafer. A wafer defect detection method as described in claim item 8, wherein the wafer after dust blowing treatment is re-inspected, if there is still a granular surface defect area, it is judged as unqualified, if there is no granular surface defect area When the surface defect area is smaller, it is judged as qualified. A wafer defect detection method as described in Claim 1, wherein, when it is determined to be a surface defect and the defect area is strip-shaped, rectangular, or other polygonal shapes with a larger area, it is directly determined to be failed. A wafer defect detection method according to claim 1, wherein, when there is an internal image defect area, it is directly judged as unqualified. A wafer defect detection method as described in Claim 1, wherein the conditions of the method judging that the detection is qualified include one or more of the following: there is no surface defect and internal defect or there is no internal defect and there is surface defect and blown This surface defect area does not exist after dust treatment. A wafer defect detection system, including CCD camera for acquiring wafer surface images; IR camera for obtaining images inside the wafer; The focusing camera is used to integrate the CCD camera and the IR camera, and automatically focus on the wafer to be inspected in the self-inspection area to obtain its surface image and internal image. A wafer defect detection system as described in Claim 13, wherein the CCD camera focuses the image of the wafer to be detected onto the CCD wafer through the lens, and accumulates phases according to the intensity of light. According to the proportional charge, the charge accumulated by each pixel is moved out point by point under the control of video timing, and after filtering and amplification processing, the image signal output that is the same as the image of the wafer to be inspected is formed. A wafer defect detection system as described in claim 13, wherein the focusing camera is provided with electronic contacts for exchanging various parameters with the camera body, and is set in the lens for storing lens focal length, maximum and minimum aperture or The ROM chip with the closest focus distance parameter, and set the corresponding working mode by setting the parameters.

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