KR20050117710A - Method of detecting defect of a wafer - Google Patents

Abstract

The wafer defect detection method for detecting defects in the appearance of the wafer first obtains an image of the entire wafer through a ccd camera of 16 million pixels or more. Next, a defect of the wafer is detected by comparing the image with the reference image of the entire preset wafer. Therefore, the wafer defect detection method detects defects of the entire wafer at once, so that the wafer inspection time can be shortened.

Description

Method of detecting defect of a wafer

The present invention relates to a wafer inspection method for inspecting defects present on a wafer, and more particularly, to a wafer defect detection method for detecting macroscopic defects present in the appearance of a wafer.

In general, a semiconductor device includes a fabrication (FAB) process for forming an electrical circuit on a silicon wafer used as a semiconductor substrate, and an electrical die for inspecting electrical characteristics of the semiconductor devices formed in the fab process. sorting) and a packaging process for encapsulating and individualizing the semiconductor devices with epoxy resin, respectively.

The fab process includes a deposition process for forming a film on a semiconductor substrate, a chemical mechanical polishing process for planarizing the film, a photolithography process for forming a photoresist pattern on the film, and the photoresist pattern. An etching process for forming the film into a pattern having electrical characteristics, an ion implantation process for implanting specific ions into a predetermined region of the semiconductor substrate, a cleaning process for removing impurities on the semiconductor substrate, and the film and pattern Inspection process for detecting a defect of the formed semiconductor substrate, and the like.

Defects in semiconductor substrates, such as foreign matter remaining on the semiconductor substrate, are recognized as an important factor that lowers the reliability and productivity of the semiconductor device due to high integration of the semiconductor device, and the importance of the inspection process for detecting the foreign matter becomes more important. It is becoming.

In order to detect a macro defect of a wafer such as a scratch of a wafer, a defect of a coating film, an environmental contaminant, a worker inspected the wafer using a microscope (5 times the objective lens). However, when using the microscope, there is a disadvantage that the inspection ability for detecting defects of the wafer is low.

In order to solve the above problem, a wafer defect was detected using a CCD camera.

1 is a view for explaining a state of imaging the image of the chip of the wafer using a CCD camera according to the prior art.

Referring to FIG. 1, an image of the chip 10 is captured by using a CCD camera 20. The CCD camera 20 has about 2 million pixels in 1200 pixels horizontally and 1600 pixels vertically. One pixel has a size of 10 mu m.

2 is a diagram showing a reference image of the chip when the chip of the wafer is normal, and FIG. 3 is a diagram showing an image of the chip when the chip of the wafer is defective.

The reference chip image 30 shown in FIG. 2 is an image of a chip in a normal state without a defect using the CCD camera 20. The reference chip image 30 is preset.

The target chip image 40 illustrated in FIG. 3 is an image of a chip of a wafer to be inspected using the CCD camera 20. When the reference chip image 30 is compared with the target chip image 40, it is determined that there is no abnormality in the target chip image 40. When the reference chip image 30 and the target chip image 40 are different from each other, it is determined that the target chip image 40 is defective, and the different portions become the defects 42.

The wafer defect detection method using the CCD camera 20 is superior in defect detection capability compared to the defect detection method using the microscope. However, the wafer defect detection method detects a defect by capturing an image having a size of one pixel of 10 μm. Therefore, in theory, a defect of 10 μm may be regarded as the minimum size of a defect that can be detected. In reality, however, a defect of about 5 μm is often detected. There is an excessive problem.

In addition, the wafer inspection by the wafer defect detection method takes about 40 seconds per wafer. This is a problem that takes about four times longer than wafer inspection using the microscope, which takes about 10 seconds per wafer.

That is, the wafer defect detection method has a problem that the detection sensitivity is excessive and takes a long time compared to the inspection purpose.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems is to provide a wafer defect detection method that has a detection sensitivity suitable for inspection purposes for detecting macroscopic defects of a wafer and can reduce the time required to detect defects of the wafer. To provide.

Another object of the present invention is to provide a wafer defect detection apparatus capable of performing a wafer defect detection method.

According to a preferred embodiment of the present invention for achieving the above object of the present invention, the wafer defect detection method first obtains an image of the entire wafer through a CCD camera. Next, defects of the wafer are detected by comparing the image with the reference image of the entire preset wafer.

An image of the whole wafer is obtained by a CCD camera of 16 million pixels or more, and the size of the pixel is 50 mu m.

A wafer defect detecting apparatus for achieving another object of the present invention detects a defect of the wafer by comparing a CCD camera for capturing the entire image of the wafer at once and an image captured by the CCD camera with a preset wafer image. It includes a detection unit for.

The CCD camera has more than 16 million pixels, and the size of the pixel is 50 mu m.

The wafer defect detection method and apparatus according to the present invention configured as described above can detect defects suitable for inspection purposes for detecting macroscopic defects. In addition, since the detection method and apparatus captures the entire image of the wafer and compares it with the reference image, it is possible to detect defects of many wafers in a short time. Therefore, the efficiency of wafer defect detection can be improved.

Hereinafter, with reference to the accompanying drawings will be described in detail a wafer defect detection apparatus and method according to a preferred embodiment of the present invention.

Methods for measuring defects in semiconductor substrates include laser scattering, optical image comparison, laser signal intensity comparison, and electron beam (E-beam).

The laser scattering method is mainly used in the inspection of non-patterned wafers, and is a method of detecting by a detector that laser beams irradiated at a predetermined angle are scattered by defects. In the optical image comparison method, an optical image of a wafer incident through a microscope is input through a CCD camera sensor, or the like, digitally converted and processed, and then compared with a reference image already stored, and then there is a defect. How to determine. The laser signal intensity comparison method is similar to the laser scattering method, but is mainly used to find macro defects. The method using the electron beam is the same as the optical image comparison method, but is distinguished in that it is a method of inspecting using a technique of a scanning electron microscope (SEM) by an electron beam instead of an optical. That is, defects are detected by imaging the shape of the wafer surface by electron beam scanning.

4 is a schematic configuration diagram illustrating a wafer defect detection apparatus according to an exemplary embodiment of the present invention, and FIG. 5 is a diagram for describing a state of photographing an image of a wafer using a CCD camera illustrated in FIG. 4. Drawing.

Referring to FIG. 4, the wafer defect detection apparatus includes a stage 110, an LED 130, a CCD camera 140, and a detector 150.

The stage 110 is composed of square or circular plates. The stage 110 is provided to have a size larger than the size of the wafer W so as to sufficiently support the wafer 120.

A light emitting diode (LED) 130 irradiates light onto the wafer 120 supported by the stage 110 to help image pickup of the wafer 120.

The CCD camera 140 is provided on the stage 110 to capture an image of the wafer 120. As shown in FIG. 5, the CCD camera 140 has 16 million pixels horizontally and 4000 pixels vertically. By using the 16 million pixel CCD camera 140, an image of the entire wafer 120 can be captured at a time. Since the length of one pixel of the CCD camera 140 is about 50 μm, it is suitable for detecting macroscopic defects such as scratches on the wafer 120, defects in the coating film, and environmental contaminants.

The detector 150 detects a defect of the wafer 120 by comparing the entire image of the wafer 120 captured by the CCD camera 140 with a preset wafer image. The preset wafer image is a wafer image in a steady state without defects.

5 is a flowchart illustrating a method for detecting defects in a wafer using a wafer defect detection apparatus according to a preferred embodiment of the present invention.

Referring to FIG. 5, first, the wafer 120 is loaded onto the stage 110. The illumination is irradiated onto the wafer 120 loaded with the LEDs 130. An optical image of the wafer W is obtained using the CCD camera 140. The optical image is captured by the CCD camera 140 of 16 million pixels at a time as an image of the entire wafer 120 (S100).

An image of the entire wafer 120 captured by the CCD camera 140 is compared with a wafer image preset by the detector 150. The defect of the wafer 120 is detected by comparing the preset wafer image having no defect in the appearance of the wafer with the wafer 120 image captured by the CCD camera 140. Since the size of one pixel of the CCD camera 140 is 50 μm, it is sufficient to detect the macro defect.

Since the entire image of the wafer 120 is compared as described above, the time taken to detect a defect of the wafer 120 may be shortened.

As described above, the wafer defect detection method according to a preferred embodiment of the present invention detects macro defects of the wafer on a wafer basis, not on a chip basis. Therefore, the macro defect of the said wafer can be detected accurately and in a short time.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

1 is a view for explaining a state of imaging the image of the chip of the wafer using a CCD camera according to the prior art.

2 is a diagram showing a reference image of the chip when the chip of the wafer is normal.

3 is a view showing an image of the chip when the chip of the wafer is defective.

4 is a schematic diagram illustrating a wafer defect detection apparatus according to an exemplary embodiment of the present invention.

FIG. 5 is a view for explaining a state of capturing an image of a wafer using the CCD camera shown in FIG. 4.

6 is a flowchart illustrating a method for detecting a defect in a wafer using a wafer defect detection apparatus according to a preferred embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

110: stage 120: wafer

122: chip 130: LED

140: CCD camera 150: detector

Claims (4)

obtaining an image of the entire wafer using a ccd camera; And Wafer defect detection method comprising the step of detecting a defect of the wafer by comparing the image with the reference image of the entire preset wafer. The method of claim 1, wherein the entire image of the wafer is obtained by a CCD camera of 16 million pixels or more. The method of claim 1, wherein the size of one pixel is 50 mu m. A CCD camera for imaging an entire image of the wafer at one time; And And a detection unit for detecting a defect of the wafer by comparing the image picked up by the CCD camera with a preset wafer image.