KR100952694B1 - Apparatus for optically recognizing wafer indentification code - Google Patents

Abstract

The present invention relates to a wafer identification code recognition device. The apparatus for recognizing a wafer identification code may include a camera unit for photographing a predetermined area of a wafer on which a wafer identification code is printed, an illumination unit for providing illumination when the camera unit is captured, a motor and a motor driving unit connected to the illumination unit to rotate or move the whole unit; A control unit for controlling the operation, a diffuser plate which is surface-treated to diffuse light from the surface, and a reflector plate which reflects light provided through the diffuser plate to be provided to an imaging area of the wafer; . The controller adjusts an illumination angle and a position of the lighting unit to provide illumination of uniform brightness to the imaging area.

The apparatus for recognizing a wafer identification code according to the present invention can acquire a plurality of images under different lighting environments, synthesize the obtained plurality of images, and process and analyze the images to accurately recognize the identification code of the wafer.

Wafer Identification Code, OCR, CCD, Imaging, Diffuser, Reflector

Description

Apparatus for optically recognizing wafer indentification code

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer identification code recognition device of a wafer prober, and more particularly, to accurately control a wafer identification code from a wafer image by controlling a lighting angle of a lighting unit and providing scattered illumination to capture a clear image of a wafer. The present invention relates to a wafer identification code recognition device that enables recognition.

In general, a semiconductor wafer prober station is used for inspection of dies in a semiconductor wafer to electrically test whether the dies in wafer state operate normally before packaging the semiconductor chips made on the semiconductor wafer. It is one of the EDS inspection equipments in the semiconductor manufacturing process of contacting the probes, applying electrical signals to test them, and determining whether the defect is good or bad. The wafer prober described above is a process equipment for reducing raw materials, time and other losses to be used in subsequent packaging and packaging test processes by early contacting and testing the pads of the die of the wafer to eliminate defective die early.

1 is a front view of the wafer prober station as a whole. Referring to FIG. 1, the wafer prober station is a wafer loader that transfers a semiconductor wafer onto a chuck or position where it can be tested in a FOUP or cassette. And a tester for inspecting a wafer placed on a chuck on the stage. A probe card is mounted on a header of the tester, and an electrical signal is applied to a chip on a wafer using the probe card and the result is measured to check whether there is an abnormality or a defect of each chip. do.

Meanwhile, the wafer prober station needs to recognize the type of the wafer to be tested, the lot number, and the wafer identification codes. For this purpose, a unique identification code is assigned to each wafer, and each identification code is displayed using an etching or printing technique at a flat surface of the wafer or at a predetermined position which is preset based on the flat surface. Recognizing such a wafer identification code using a camera is called optical character recognition (hereinafter referred to as 'OCR').

2 is a schematic cross-sectional view of an OCR device of a wafer prober station according to the prior art. Referring to FIG. 1, a conventional OCR device is combined with a camera module and a lighting unit. A process of identifying the wafer identification code ID using the OCR device having the above-described configuration will be briefly described. First, the wafer located in the wafer seating table is moved or rotated by controlling the motor and the motor driving unit to recognize the flat / notch of the wafer as the light sensor and the centering camera. Next, the CCD camera for identifying the wafer ID captures the area where the wafer ID is printed, and processes and analyzes the captured image to recognize the ID of the wafer.

By the way, in recognizing the wafer identification code, the angle or amount of light on which the wafer surface reflects illumination differs depending on the surface treatment method, the wafer identification code printing method, or the like for the area where the wafer identification code is printed. As a result, in the conventional OCR apparatus in which the same illumination position and angle are always provided, the wafer identification code cannot be properly recognized as the type of the wafer is changed.

An object of the present invention for solving the above-described problems is to provide a wafer identification code recognition apparatus that can accurately recognize the identification code by adjusting the angle and the amount of light provided to the surface of the wafer.

Another object of the present invention is to acquire a plurality of images by using lighting having different characteristics, to synthesize a plurality of images obtained under different lighting and to process the image, so that the identification ID of the wafer can be accurately recognized It is to provide a wafer identification code recognition device.

A first aspect of the present invention for achieving the above technical problem relates to a wafer identification code recognition device for recognizing a wafer identification code displayed on the surface of the wafer, the wafer identification code recognition device,

A camera unit for capturing an image of a predetermined position of the wafer;

A plurality of lighting unit for providing a predetermined illumination to the surface of the wafer to be inspected when photographing the camera unit,

A plurality of motors connected to each of the lighting units to rotate or move the lighting units;

A motor driver connected to the motors to drive the motors;

And a control unit for controlling the operation of the motor driving unit, the camera unit, and the lighting unit, and the control unit transmits a driving signal for the motor to the motor driving unit to control an illumination angle of the lighting unit, thereby to capture the camera unit. The illumination can be accurately provided to the imaging area of the wafer. The controller analyzes an image of a wafer provided from the camera unit after image processing to recognize a wafer identification code.

A wafer identification code recognition device according to a second aspect of the present invention,

A camera unit for capturing an image of a predetermined position of the wafer;

A plurality of lighting unit for providing a predetermined illumination to the surface of the wafer to be inspected when photographing the camera unit,

Control unit for controlling the operation of the camera unit and the lighting unit,

A diffuser plate which is surface-treated to diffuse light and is disposed in front of the lighting unit;

And a reflecting plate for reflecting the light of the lighting unit provided through the diffusion plate to the imaging area of the wafer, and the light provided from the lighting unit is scattered by the diffusion plate and the reflecting plate to provide illumination of uniform brightness to the imaging area. Be sure to

The control unit of the apparatus for recognizing a wafer identification code according to the above-mentioned features obtains a plurality of images of the wafer by adjusting the illumination unit and the camera unit, synthesizes the obtained images, and generates one composite image. An image is used to recognize a wafer identification number of the wafer, and the plurality of images are captured under different lighting environments.

In particular, the controller compares the image data of each pixel of the composite image with a preset reference value and sets the image data of the pixel to '1' if the image data of the pixel is larger than the reference value. If the image data is smaller than the reference value, it is preferable to set the image data of the corresponding pixel to '0', change the synthesized image into a binary image represented by binary data, and recognize a wafer identification number using the changed binary image. Do.

FIG. 5 is a view comparing images captured by adjusting a lighting angle of a lighting unit by a wafer identification code recognition device according to an exemplary embodiment of the present invention and captured images without adjusting the lighting angle. 5 (a) is an image captured without adjusting the illumination angle of the lighting unit 312 of Figure 3, Figure 5 (b) and (c) is an image captured after adjusting the illumination angle of the lighting unit 312 admit. 5, by adjusting the illumination angle of the lighting unit according to the present invention, the captured image is more clear and as a result the identification code of the wafer can be easily recognized.

6 to 9 are views comparing images captured by using conventional basic lighting and images captured using a diffusion plate and a reflecting plate according to the present invention. 6 to 9 (a) is an image according to the prior art, (b) is an image according to the present invention. 6 to 9, it can be seen that according to the present invention the image captured in the light scattering state using the diffuser plate and the reflector plate is clearer, so that the identification code of the wafer can be more easily recognized. do.

Figure 6 (a) is an image of a state that can not recognize the identification code of the wafer due to damage such as scratches on the identification code of the wafer, Figure 6 (b) is a diffusion plate and a reflecting plate according to the present invention It is an image that captures the identification code of the wafer by penetrating the scratch.

FIG. 7 (a) is an image capturing a state in which the identification code of the wafer overlaps the pattern of the wafer so that the identification code cannot be recognized due to the wafer pattern, and FIG. 7 (b) is diffused according to the present invention. This image captures the state that only the identification code of the wafer is highlighted using the plate and the reflecting plate without being greatly influenced by the surrounding pattern.

8 (a) is an image capturing a state in which a strip engraved on the surface of the wafer is superimposed on the identification code of the wafer and because of the strip engraved on the surface, characters of the identification code of the wafer may be confused and recognized by other characters. Figure 8 (b) is an image capturing the state of killing the effect of the band engraved on the surface using a diffusion plate and a reflecting plate in accordance with the present invention to highlight only the identification code of the wafer.

9 (a) is an image capturing a state in which the identification code of the wafer cannot be easily recognized due to the fingerprint when the fingerprint of the person is buried in the identification code of the wafer, and FIG. 9 (b) shows the present invention. Accordingly, the image of the identification code of the wafer is captured by transmitting a fingerprint embedded in the identification code of the wafer using a diffusion plate and a reflection plate.

First Example

Hereinafter, a wafer identification code recognition device according to a first embodiment of the present invention will be described in detail with reference to the accompanying drawings. 3 is a block diagram schematically showing the configuration of the wafer identification code recognition device 30 according to the present invention, and FIG. 4 is a sectional view schematically showing only essential components of the wafer identification code recognition device 30. Hereinafter, the configuration and operation of the wafer identification code recognition device 30 according to the present invention will be described in detail with reference to FIGS. 3 and 4.

3 and 4, the wafer identification code recognizing apparatus 30 according to the first embodiment of the present invention is an apparatus for recognizing a wafer identification code displayed at a predetermined position on the surface of a wafer, and includes a camera unit 300, At least one lighting unit (310, 312), motors 320 and 324 connected to each of the lighting unit, the motor driving unit 330, a control unit 340 for controlling the overall operation, the reflecting plate 350 and the diffusion plate 360 is provided. .

The camera unit 300 captures an image of a predetermined position of the wafer and provides it to the controller 340.

The illumination units 310 and 312 are illumination lamps that provide illumination to the surface of the wafer as an inspection object when the camera unit is photographed, and includes a plurality of illumination units in the wafer identification code recognition device. The motors 320 and 324 are connected to each of the lighting units 310 and 312 to rotate or move the lighting unit, and are driven by the motor driving unit 330. Meanwhile, the motors 320 and 324 according to the present invention may use a step motor. The motor driver 330 drives the motors 320 and 324 according to a drive signal transmitted from the controller 340. Accordingly, the lighting units 310 and 312 are rotated or moved by a motor driven according to a driving signal provided from the control unit 340, whereby the angle and position of the lighting are adjusted by the control unit.

The control unit 340 controls the operation of each component module of the wafer identification code recognition device as a whole, and controls the operation of the motor driving unit, the camera unit, and the lighting unit. In addition, the controller 340 recognizes a wafer identification code by analyzing and analyzing images of the wafer provided from the camera unit.

In particular, the control unit 340 according to the present invention transmits a drive signal for the motor to the motor driving unit to control the angle and position of each lighting unit, so that the illumination is accurately provided to the imaging area of the wafer to be captured by the camera unit To help.

The diffusion plate 350 is surface-treated to diffuse light incident on the surface, and is disposed in front of the lighting unit. Therefore, the light provided from the lighting unit is diffused by the diffusion plate 350.

The reflective plate 360 reflects the light of the lighting unit provided through the diffusion plate 350 to the imaging area of the wafer, and the surface of the reflective plate is formed to have a curved surface having a predetermined curvature.

The light provided from the lighting unit is scattered by the diffusion plate 350 and the reflecting plate 360 to remove noise such as scratches or fingerprints that may be included in the image captured by the camera unit.

2nd Example

Hereinafter, a wafer identification code recognition device according to a second embodiment of the present invention will be described in detail with reference to the accompanying drawings. The apparatus for recognizing a wafer identification code according to the second embodiment acquires a plurality of images in an illumination environment having different characteristics, synthesizes the obtained plurality of images, and analyzes the same, thereby accurately recognizing the wafer identification code. The configuration of the wafer identification code recognizing apparatus according to the present embodiment is the same as that of the first embodiment, except that only the operation of the controller is partially different. Therefore, the second embodiment only describes the control unit of the wafer identification code recognition apparatus, and descriptions of other components are overlapped with those of the first embodiment, and thus description thereof will be omitted.

10 are images captured in an environment in which the angles and positions of illumination are different with respect to the same wafer using the wafer identification code recognition device according to the present invention. 10, it can be seen that the states of the wafer identification codes of the captured image are different from each other according to the position and angle of illumination. (A) of FIG. 10 is an image in which the vertical scratches exist in the wafer identification code, and FIG. 10 (b) is an image in which the horizontal scratches exist in the wafer identification code, and FIG. It is an image in which both scratches in the direction and the horizontal direction are minute.

The controller of the apparatus for recognizing a wafer identification code according to the present embodiment provides a first driving signal for adjusting the angle and position of each lighting unit to the motor driving unit, and the motor driving unit provides a motor connected to each lighting unit according to the first driving signal. Drive it. After the position and angle of the lighting unit are adjusted, the camera unit photographs the first image of the wafer and transmits the captured first image to the controller.

The control unit provides a second driving signal to the motor driving unit for changing the angle and position of the lighting unit, and the motor driving unit drives the motors connected to the respective lighting units according to the second driving signal to readjust the position and angle of the lighting unit. . Next, the camera unit captures a second image of the wafer and transmits the captured second image to the controller.

The controller repeatedly performs the above-described process several times to obtain a plurality of images of the wafer, and then synthesizes the obtained images to generate a composite image. In the present invention, as a method of synthesizing the obtained plurality of images, a method of obtaining an average value after combining image data of pixels corresponding to each other of all images is used. However, other image synthesis methods widely used in the art may be used.

Next, the controller generates a new image to remove noise and to clearly display only a wafer identification code by applying a preset algorithm to the composite image. Hereinafter, the algorithm used to generate the new image in the present invention will be described. First, after setting the reference value, the image data of each pixel of the composite image is compared with the reference value, and if the image data of the pixel is larger than the reference value, the image data of the pixel is changed to '1', and if the corresponding pixel If the image data is smaller than the reference value, it is changed to '0'. By performing the above-described process for all the pixels, the composite image is changed to a binary image represented by binary data. If it is difficult to accurately recognize the wafer identification code from the binary image, after correcting the reference value, a binary image is generated again from the synthesized image using the modified reference value, and the wafer identification code is recognized from the binary image.

FIG. 11 is an image illustrating an example in which the controller of the apparatus for recognizing a wafer identification code according to the present embodiment changes the synthesized image into a new binary image displayed in black and white. The controller recognizes the wafer identification code by analyzing the newly generated binary image.

Although the present invention has been described above with reference to preferred embodiments thereof, this is merely an example and is not intended to limit the present invention, and those skilled in the art do not depart from the essential characteristics of the present invention. It will be appreciated that various modifications and applications which are not illustrated above in the scope are possible. And differences relating to such modifications and applications should be construed as being included in the scope of the invention as defined in the appended claims.

The apparatus for recognizing a wafer identification code according to the present invention can be widely used for equipment that needs to recognize a wafer identification code engraved on a wafer, such as a wafer prober.

1 is a block diagram showing a general wafer prober station as a whole.

2 is a block diagram schematically showing a wafer identification code recognition device according to the prior art.

3 is a block diagram schematically illustrating an apparatus for recognizing a wafer identification code according to a first embodiment of the present invention.

4 is a configuration diagram schematically showing a wafer identification code recognition device according to a first embodiment of the present invention.

5 is a view comparing images captured by controlling the lighting angle of the lighting unit according to the present invention and images captured without controlling the lighting angle of the lighting unit according to the prior art.

6 to 9 are views comparing images captured using a diffusion plate and a reflecting plate according to the present invention and images captured according to the prior art.

10 are images captured in an environment in which the angles and positions of illumination are different with respect to the same wafer using the wafer identification code recognition device according to the present invention.

FIG. 11 is an image exemplarily illustrating a state in which the controller of the apparatus for recognizing a wafer identification code according to the second embodiment of the present invention changes the synthesized image into a new binary image displayed in black and white.

<Description of the symbols for the main parts of the drawings>

30: wafer identification code recognition device

300: camera unit

310, 312: lighting unit

320, 324 motor

330: motor drive unit

340: control unit

350: reflector

360: diffuser plate

Claims (7)

In the wafer identification code recognition device for recognizing a wafer identification code displayed on the surface of the wafer, A camera unit for capturing an image of a predetermined position of the wafer; A plurality of illumination units providing predetermined illumination to a surface of a wafer to be inspected when the camera unit is photographed; A plurality of motors connected to each of the lighting units to rotate or move the lighting units; A plurality of motor driving units connected to each of the motors to drive the corresponding motors; A control unit controlling the operation of the motor driving unit, the camera unit, and the lighting unit, and recognizing a wafer identification code of a wafer using images provided from the camera unit; And the control unit transmits a driving signal for the motor to the motor driving unit to control the illumination angle of the lighting unit, so that the illumination can be accurately provided to the imaging area of the wafer to be photographed by the camera unit. The control unit controls the operation of the lighting unit and the camera unit to obtain a plurality of images of the wafer, synthesizes the obtained images to generate one composite image, and sets image data of each pixel of the synthesized image in advance. If the image data of the pixel is larger than the reference value, the image data of the pixel is set to '1'. If the image data of the pixel is smaller than the reference value, the image data of the pixel is set to '0'. Set to change the composite image into a binary image represented by binary data, and recognize a wafer identification number using the changed binary image. And a plurality of images are captured under different lighting conditions. delete The wafer identification code recognition apparatus of claim 1, further comprising a diffusion plate surface-treated so that the irradiated light is diffused, and a reflection plate reflecting the light passing through the diffusion plate to the imaging area of the wafer, wherein the wafer identification code recognition device is provided from the illumination unit. Wafer identification code recognition device characterized in that to be provided to the imaging area of the wafer after scattering the light. 4. The apparatus of claim 3, wherein the reflective plate has a curved surface. The wafer identification code recognition according to claim 3, wherein the diffuser plate is disposed in front of the illumination unit, and the reflector plate is disposed at a position at which light passing through the diffuser plate is reflected to an imaging area of the wafer. Device. The wafer identification code recognition apparatus according to claim 1, wherein the wafer identification code recognition apparatus arranges a diffusion plate in front of the illumination unit, and the diffusion plate is surface-treated to diffuse light provided from the illumination unit. The wafer identification code recognition apparatus according to claim 1, wherein the wafer identification code recognition apparatus further comprises a reflector for reflecting light provided from the illumination unit to an imaging area of the wafer.

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