KR200188365Y1 - Apparatus for inspecting the defects on the wafer periphery - Google Patents

Abstract

The present invention is to inspect the defect of the wafer edge. The inspection apparatus inspects the defect by processing the image information of the edge of the semiconductor wafer. The inspection device includes a wafer moving device and an image information acquisition device. An apparatus for moving a wafer accommodates the semiconductor wafer and can move or rotate the wafer. The image information acquisition device is installed to face the wafer edge in order to scan the wafer edge to acquire image information. The wafer moving device linearly moves the wafer in a direction parallel to the plane of the wafer surface when the image information obtaining device obtains image information on the straight portion of the wafer edge, and the image information obtaining device. Rotates the wafer along the circumferential direction when is obtaining image information on the curved portion of the wafer edge.

Description

Wafer Edge Defect Inspection System {APPARATUS FOR INSPECTING THE DEFECTS ON THE WAFER PERIPHERY}

The present invention relates to an apparatus for inspecting wafer edge defects in a semiconductor device manufacturing plant. In particular, an apparatus for inspecting edge defects by processing an image signal obtained by scanning a wafer edge with a line scanning camera while rotating or linearly moving a wafer It is about.

Generally, wafers, which are widely used in semiconductor device manufacturing, are subjected to thermal or physical stress during a plurality of processes. At this time, defects such as cracks in the wafer edge are likely to cause serious wafer loss. In other words, if there are even small cracks on the edges, new cracks may be generated or cracks may propagate to other parts of the wafer due to thermal or physical stress during the process. In severe cases, the wafer may break during the heat treatment process. In general, in a clean room, the process is performed in a state where a plurality of wafers (for example, about 50) are mounted in a container containing a wafer such as a carrier. Therefore, if one wafer is broken, it is likely to cause very serious economic and time loss due to the contamination of particles generated from the broken wafers, and the loss of all other wafers mounted together or other wafers in the same clean room.

Nevertheless, no device or proper inspection method for inspecting wafer edge defects in advance has yet been proposed. Visual inspection does not find small defects in microns. In addition, the edge inspection method is required to be automated according to the shape of the wafer. This is because it is necessary to harmonize with other processes of the semiconductor factory Fab.

The object of the present invention is to provide a device that can effectively inspect the defects of the wafer edge, overcoming the limitations and problems of the prior art as described above.

It is another object of the present invention to provide an automated wafer edge defect inspection apparatus that is in harmony with other semiconductor device fabrication processes.

1 is a front view of a wafer edge defect inspection apparatus according to an embodiment of the present invention.

2 is a system configuration diagram of the inspection device of FIG.

3 is a front view of a wafer moving device constituting the inspection device of FIG.

4 is a plan view of a linear movement mechanism for linearly moving a wafer among the wafer moving apparatuses of the inspection apparatus of FIG.

5A and 5B are right and front views of the image information acquisition device constituting the inspection device of FIG. 1, respectively.

6 is a flow chart of the wafer edge inspection method according to an embodiment of the present invention.

7 is a view showing one of the screen output to the wafer edge inspection result display unit according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

8: Wafer edge defect inspection device 10: Image information acquisition device

19: wafer moving device 20: flat aligner

30: linear movement mechanism 50: system control unit

60: data storage device 70: data processing device

80: display unit 90: input unit

In the present invention, a reference position is preset on a wafer edge, and image information is acquired by scanning from the reference position with an image information acquisition device. At this time, the angle between the light incident on the image information acquisition device and the tangent of the edge from the position on the wafer edge to acquire the image information is kept constant during scanning. After acquiring the image information, the acquired image information is appropriately processed to determine a defect. Defective locations are also identified.

As an example, in the case where the edge of the wafer has a straight portion and a curved portion, the wafer is linearly moved when scanning the straight portion, and the wafer is rotated when the curved portion of the wafer is scanned.

According to one aspect of the present invention, an apparatus for inspecting a defect by processing the image information of the edge of the wafer,

A wafer holding device;

And an image information acquisition device installed to face the wafer edge so as to scan the wafer edge to acquire image information.

A wafer edge defect inspection apparatus is provided between a wafer accommodated in the wafer accommodation device and the image information acquisition device such that relative movement is performed to scan the entire wafer edge.

Referring to the drawings, the structure of the wafer edge inspection apparatus according to an embodiment of the present invention, the wafer edge inspection method will be described in detail.

<Structure of Wafer Rim Inspection System>

1 is a front view of a wafer edge defect inspection apparatus according to an embodiment of the present invention, Figure 2 is an overall system configuration of the inspection apparatus. 1 and 2, the wafer edge defect inspection apparatus 8 according to an embodiment of the present invention includes an image information acquisition device 10, a flat aligner 20, and a linear movement mechanism 30. It may be composed of a wafer moving device 19 and a data storage device 60, a data processing device 70, a display unit 80, an input unit 90, and a system control unit 50 for controlling all of them. . The image information acquisition device 10 captures an image of a wafer edge. The flat aligner 20 can hold a plurality of wafers and rotate the wafers. The linear movement mechanism 30 has a flat aligner 20 mounted thereon, and linearly moves the flat aligner 20 to linearly move the wafer. The system controller 50 is connected to the image information acquisition device 10, the flat aligner 20, and the linear movement mechanism 30, respectively, to control them so as to capture a wafer edge image, and to store the captured image data, Control the entire system, including processing and display.

FIG. 5A illustrates a front view of the image information acquisition device 10, and FIG. 5B illustrates a side view of the image information acquisition device 10. 1 and 5, the image information acquisition device 10 includes a camera 11 and an illumination device 15 including an illumination lamp or a lamp. The camera 11 and the illumination device 15 are respectively installed on the horizontal support 14 and the vertical support 18 provided in the inspection apparatus main body. The camera 11 includes a lens portion 12 and a body portion 13, and the body portion 13 is fixed to the horizontal horizontal support 14 so that the lens faces downward (wafer).

As one type of image scanner, the camera 11 used in this embodiment preferably uses a digital line scanning camera. In particular, when the wafer edge defect size is 0.5 mm or less and high resolution scanning is required, it is preferable to use a CCD line scanning camera. CCD line-scanning cameras with pixel counts of 2048 or higher enable high-resolution image scanning, effectively inspecting wafer edge defects. An example of a CCD line scanning camera that can be used in one embodiment of the present invention is a DALSA CL-CB 2048 line scanning camera sold by DALSA INC. (Www.dalsa.com).

The lighting device 15 includes a lamp 17 and a socket 16, and two lamps 17 are preferably provided on the left and right of the lens part 12 of the camera 11. One example of the lamp 17 of the lighting device 15 is a three-wavelength fluorescent light bulb. As shown in Figure 1, it is preferable to install the illumination lamp such that the longitudinal direction of the illumination lamp is parallel to the plane of the wafer surface. In addition, it is preferable to position the light emitted from the lighting device 15 so as not to directly shine into the camera lens. The output of the lamp 17 of the lighting device 15 depends on the sensitivity of the camera 11 and the distance between the lamp 17 and the wafer 40 and the distance between the camera lens and the wafer 40. The socket portion 16 of the lighting device 15 is supported and fixed by the vertical support 18. This vertical support 18 is fixed to the frame 10a of the inspection apparatus 10. In the embodiment shown in FIG. 5, the relative positions of the lighting device 15 and the camera 11 remain the same.

3 is a front view of a wafer moving device 19 composed of a linear movement mechanism 30 and a flat aligner 20 placed thereon. The wafer 40 shown in FIG. 3 has a general shape in the form of a circular disk, but one portion constitutes a border of a straight string. Thus, the edge of the wafer 40 is divided into a straight portion 41 and a curved portion 42 forming a circumferential edge. When the camera 11 scans the edge of the wafer 40 to acquire image information, the straight portion 41 and the curved portion 42 are incident on the camera lens by reflecting the light of the lamp 17. The angle and amount of light are different. Therefore, there is a need for an apparatus that allows the wafer 40 to move linearly when scanning the straight portion 41 and allows the wafer 40 to rotate when scanning the curved portion 42. In one embodiment of the wafer moving device 19 for realizing this, there is provided a table which linearly moves with a flat aligner 20 for rotating the wafer about an axis perpendicular to the plane formed by the wafer surface. The linear movement mechanism 30 is comprised.

However, unlike the above embodiment, in another embodiment of the present invention to move any one of the camera 11 or the lighting device 15 while only rotating the wafer 40, the relative position within a certain range It can be configured to be adjusted in, or may be configured to move the camera 11 and the lighting device 15 together.

Referring again to FIG. 3, the flat aligner 20 includes a cassette 21 and a frame 25 containing a wafer 40. The cassette 21 is configured to contain a plurality of wafers 40 (for example 25 or 50), and side supports 22 are provided on both sides of the cassette 21. The frame 25 includes a vertical support 24, and a roller 23 is installed on the support 24. The roller 23 is installed in the frame 25 so as to pass through the lower portion of the cassette 21 in the shape of a long cylindrical bar, and contacts the edge of the plurality of wafers 40 contained in the cassette 21 from the bottom. Therefore, when the roller 23 rotates in contact with the edge curve of the wafer 40, the wafer 40 also rotates. The cassette 21 and the frame 25 may be separately configured to be assembled in such a manner that the cassette 21 is placed on the frame 25, or the cassette 21 and the frame 25 may be integrally formed. . The flat aligner 20 can also use a well-known thing. An example of the flat aligner 20 used in one embodiment of the present invention may be an EZ Guide flat finder sold by H-Square.

4 shows a plan view of the linear movement mechanism 30. 3 and 4, the linear movement mechanism 30 includes two tables 38 and 39, a guide device, and a driving device.

The upper and lower two tables 38 and 39 have a rectangular shape and the upper linear slide table 39 is mounted on the lower support table 38. On the upper table 39, a flat aligner holder 35 for supporting and fixing the flat aligner 20 is installed. The flat aligner holder 35 is formed on the upper table 39 in the form of a quadrilateral, but the present invention is not limited to this configuration. The lower table 38 is provided with stoppers 37 for limiting the distance that the upper table 39 goes, and two are provided on both sides of the lower table 38.

The guide device is a device for guiding a relative motion between the upper and lower tables 38 and 39, and includes a guide rail 33 and a linear bearing 36. Two guide rails 33 are fixed and installed on the lower table 38 so as to extend in a direction aligned with the straight portions 41 of the wafer 40 to be installed. The linear bearing 36 is fixed and installed under the upper table 39 so as to interact with the guide rail 33. The linear bearing 36 is coupled to the guide rail 33 to allow the upper table 39 to linearly move. . It is preferable that four linear bearings 36 are provided, two for each guide rail 33, but are not necessarily limited thereto.

The drive device is a device for driving the linear motion of the upper table 39. The drive device includes a step motor 31, a ball screw 32, and a sensor device 34, and is installed in the lower table 38. The step motor 31 is driven by the drive signal of the system controller 50, and provides power to the upper table 39 to linearly move on the lower table 38. The ball screw 32 is a device that transfers the circular motion of the stepper motor 31 into the linear motion of the upper table 39. The ball screw 32 is connected to the upper table 39 and transfers the power of the stepper motor 31 to the upper table 39. To pass on. The sensor device 34 detects the position of the upper table 39 and transmits the detected position to the system controller 50 to control linear motion such as stopping or changing the moving direction of the upper table 39.

The data storage device 60 is connected to the system controller 50 to store image information of the edge of the wafer 40 input by the camera 11. In addition, the result processed by the data processing apparatus 70 described later is also stored. As an embodiment of the data storage device 60, a hard disk drive or other information recording device may be used.

The data processing apparatus 70 is connected to the system controller 50 to process the image information of the edge of the wafer 40 collected by the camera 11 and stored in the storage device 60 to determine whether there is a defect or the like. 40) Analyze and organize information about the border. The result is transmitted to the display unit 80. As an example of the data processing apparatus 70, a microprocessor can be used.

The display unit 80 is connected to the system control unit 50 (or may be directly connected to the data processing unit), and is connected to the image information or the data processing unit 70 of the edge of the wafer 40 stored in the data storage unit 60. The information processed by is displayed to be visible. As the display unit 80, a general monitor may be used, and a touch screen device integrated with the input unit 90 described later may be used.

The input unit 90 is connected to the system control unit 50 to drive the image information acquisition device 10 or the wafer moving device 19, or input a command for storing or processing image information data. As an example of the input unit 90, a general keyboard (keyboard), a touch screen, a mouse, or the like can be used.

The system control unit 50 is connected to all other parts of the wafer edge defect inspection apparatus of the present invention and controls the driving and information processing thereof. As an embodiment of the system controller 50, the system controller 50 may be connected to a computer processing unit (CPU) or may be implemented as a separate device having a separate microprocessor or the like.

In the above embodiment, the wafer moving device 19 is described as being composed of the flat aligner 20 and the linear movement mechanism 30, but the present invention is not limited thereto. Any other device capable of rotating or linearly moving the wafer 40 may be used as the wafer moving device 19. Other parts may also be modified appropriately to meet the purposes of the present invention to form other embodiments, it will be readily apparent to those skilled in the art that such modified embodiments are also within the scope of the present invention.

<Wafer Edging Inspection Process>

6 is a flowchart illustrating a wafer edge inspection method according to an embodiment of the present invention. Referring to Figures 1 to 6 the wafer edge inspection method will be described in detail.

First, the wafers 40 are placed in the cassette 21 of the flat aligner 20. The flat aligner 20 on which the cassette 21 is mounted is attached to the linear movement mechanism 30. In this case, as can be seen from the figure, the linear movement mechanism 30 moves in parallel (ie, the X axis of FIG. 3) with the plane forming the surface of the wafer 40 or in parallel with the straight portion ( It will be appreciated that the wafer is placed so that the extension direction of 41) coincides.

After mounting the wafer, the lot number of the wafer contained in one cassette is input through the input unit 90. The wafers 40 that make up a lot consist of as many wafers 40 as one cassette. The lot number is generally a suitable number and symbol that combines the type of wafer, manufacturer, inspection date, and serial number. Consists of.

After entering the lot number, the wafers 40 are aligned. In other words, in order to know where the defects found in the scanning process exist at the edge of the wafer 40, the reference position is first determined when the wafer 40 is rotated or linearly moved. One end of the straight portion 41 of the wafer 40 may be set to such a reference position. As shown in Fig. 3, when the X-Y axis coordinate plane (this plane is a plane parallel to the wafer surface) is set, the preset reference positions on each wafer edge are aligned so as to have the same X coordinate value and Y coordinate value. In other words, the preset reference positions of each wafer are aligned such that they are located on a straight line perpendicular to the plane of the wafer's surface.

After wafer alignment, the wafer edge is scanned by moving the wafer 40 to the camera 11. Preferably, the straight portion 41 of the edge of the wafer 40 is first scanned. When the inspection of the wafer is commanded through the input unit 90, the system control unit 50 drives the linear movement mechanism 30 of the wafer moving device 19 to linearly move. That is, when the upper table 39 is linearly moved in the X-axis direction while the upper table 39 is guided on the lower table 38 by rotating the step motor 31, the flat ear mounted on the upper table 39 is rotated. Since the liner 20 also makes a linear motion, the image of the straight portion 41 of the edge of the wafer 40 is photographed (taken) by the camera 11. Since the camera 11 scans two-dimensional images at a time instead of scanning them line by line, when scanning while linearly moving the wafer 40 at a constant speed, all the images of the straight portions 41 of the edge of the wafer 40 are all scanned. Is entered. The position of the upper table 39 is sensed by the sensor device 34 mounted on the lower table 38, and the linear motion of the wafer 40 is controlled by the system controller 50 so that the edge straight portion 41 is formed. Scanning is performed without exception.

After the scanning of the straight portion 41 is finished, the curved portion 42 is scanned. First, the wafer 40 is linearly moved so that the center axis of the camera 11 passes through the center point of the wafer curved portion 42. Thereafter, a preset reference position (for example, one of the points forming the boundary between the straight portion 41 and the curved portion 42 of the edge) is placed near the center of the scanning by the camera 11. . The roller 23 of the flat aligner 20 is then driven by the system control unit 50 to rotate. Since the wafer 40 in contact with the roller 23 is also rotated by the rotation of the roller 23, the curved portion 42 of the edge is also scanned to capture an image. At this time, the image captured by the camera 11 is converted into digital data and output to the outside. After the rotational motion is controlled so that the edge curve portion 42 is scanned without missing, the roller 23 stops by a signal from the system controller 50.

After both the edge portion 41 and the curved portion 42 of the wafer 40 are scanned and these images are taken, these image data are stored in the storage device 60. The data processing apparatus 70 takes out this data and processes it, and analyzes whether there exists a defect, such as a crack, on an edge. Typically, the edge image information of a wafer corresponding to one lot consists of several frames. In order to work efficiently, it is desirable to store and process data of already completed frames while completing one frame.

For example, an image data processing method may be used in a data processing process for detecting a defect of an edge. As an example of the defect retrieval method, the data processing apparatus 70 may determine whether the edge is defective by comparing the image of the edge of the wafer 40 with no defect previously inputted with the image information of the edge of the scanned wafer 40. Or, if there is a defect in the edge of the light reflected from the portion or the amount of light, such as the irregular changes will be seen by those skilled in the art will be able to understand that the defects and their size may be calculated by calculating them.

When the data has been processed, the output is printed and stored on the other hand. Data that has been searched for defects in the wafer 40 by the data processing device 70 is stored in the data storage device 60, and is output through the display unit 80. In addition, the result displayed on the display unit 80 may be output and printed by a printer. In addition, the image information data of the edge of the wafer 40 stored in the data storage device 60 may be displayed or output printed at any time thereafter, according to the needs of the user. That is, when the lot number is input through the input unit 90, the data corresponding to the lot is displayed on the display unit 80 so that the result can be checked again or printed at any time.

7 illustrates one of the screens output to the wafer edge inspection result display unit 80 according to an embodiment of the present invention. In the case of 25 wafers constituting a lot, for example, data processing results of defects in the edges of the 5th wafer and the 23rd wafer are displayed. On the left side of the screen of the display unit 80, 25 edge wafers are output. For example, if there is no defect, 'OK' is displayed next to the serial number of the wafer, and if there is a defect, 'R' is displayed next to the serial number of the wafer, and the number is displayed in a different color. At this time, if the number of the defective wafer or 'R' is selected, the lot number and the serial number of the defective wafer are displayed on the upper right side of the screen, and the position of the defect with respect to the designated defective wafer below. And size, number, etc. are displayed. As shown in the example of the figure, if the defects present in the edges are displayed at different sizes (for example, different colors are displayed), it is easy to see the result. If the serial number of the defective wafer is selected as another in the previous screen, the defect position, size, and number of the corresponding wafer may be displayed again (for example, to 5 in FIG. 7).

In the embodiment of the present invention described above as a method of scanning the straight portion 41 and the curved portion 42 of the edge of the wafer 40 differently, first scanning the straight portion 41 while linearly moving the wafer 40 Then, the method of scanning the curved portion 42 while rotating the wafer 40 has been described. However, alternative embodiments may be implemented. That is, when the reflection angle of the light is changed by the difference between the straight portion 41 and the curved portion 42 by rotating only the wafer 40 without the linear movement, the lighting device 15 or the camera 11 is moved. It may be configured so that the reflected light can enter the lens of the camera (11). In this case, when scanning the straight portion 41 of the wafer 40, it is best to move the illumination device 15 and the camera 11 together so that the reflected light is always incident at a constant angle with respect to the camera 11. Preferably, only one of the lighting device 15 and the camera 11 may be configured to move. Inspection apparatus and method for implementing these embodiments also fall within the spirit and scope of the present invention.

In the above embodiment of the present invention, the wafer has been described as having a straight portion and a curved portion. In contrast, in the case of a 12-inch wafer, the entire edge is formed in a circular shape and one notch is provided at the circular edge. When inspecting the edge of such a wafer, the wafer is mounted on the cassette 21 of the flat aligner 20, and then the linear movement mechanism 30 is moved so that the center point of the circular edge of the wafer and the center axis of the camera 11 Match. The flat aligner 20 is then driven to align a preset reference position (eg notch) of each wafer. Thereafter, the image of the edge is scanned while rotating the wafer to obtain image information. As such, the wafer inspection apparatus according to the present invention can inspect the defects of the wafer edge corresponding to the shapes of the various wafers.

According to the apparatus for inspecting the defects of the wafer edge of the present invention, first, since wafers with defects in the edge can be identified before proceeding with the overall process of the wafer, the wafer is broken due to the wafer edge defect in the subsequent heat treatment process. There is an effect that the loss of the wafer can be prevented in advance. In addition, uniform image information can be scanned at all times by linearly or curvedly moving the wafer. In addition, by providing an automated inspection apparatus that can effectively inspect defects on the wafer edge, it can be suitably matched with other semiconductor device manufacturing processes.

Claims (8)

For processing defects on the wafer edge by processing the image information of the wafer edge, A wafer holding device; And an image information acquisition device installed to face the wafer edge so as to scan the wafer edge to acquire image information. Wafer edge defect inspection apparatus characterized in that the relative movement between the wafer accommodated in the wafer containing device and the image information acquisition device to scan the entire wafer edge. The apparatus of claim 1, wherein the image information acquisition device comprises a camera and an illumination device, and scans while moving the camera and the illumination device. The device of claim 1, wherein the wafer receiving device comprises a wafer moving device; The wafer moving device is a plane in which the surface of the wafer forms the wafer when the image information acquisition device has a straight portion formed on the edge of the wafer, and the image information acquisition device obtains image information about the straight portion. Along the direction parallel to And the wafer is rotated in the circumferential direction when the image information acquisition device is acquiring the image information on the curved portion of the wafer edge. The method of claim 3, The wafer moving device includes a linear movement mechanism having a linear movement table capable of linear movement; A plurality of wafers mounted in parallel on the linear movement table and accommodating a plurality of wafers of the same shape having a preset reference position on an edge in parallel, and aligning the plurality of wafers so that the reference positions of the respective wafers are in line; In order to rotate the plurality of wafers along the circumferential direction, provided with a flat aligner mounted on the linear movement table, And the flat aligner is placed on the linear movement table such that the linear movement direction of the linear movement table is parallel to the plane of the surface of the wafer. 5. The wafer edge defect inspection apparatus according to any one of claims 1, 3, and 4, wherein the image information acquisition device is a CCD line scanning camera. The method according to any one of claims 1 to 4, A data processing device which processes the image information of the wafer edge acquired by the image information obtaining device and determines whether there is a defect; A data storage device for storing image information of the wafer edges acquired by the image information acquisition device and data processed by the data processing device; An output device for outputting a processing result of the data processing device; And a system control unit for controlling the image information acquisition device, data storage device, data processing device, and output device. 5. The apparatus of claim 4, wherein the linear movement mechanism comprises: a lower support table; An upper linear moving table placed on the support table and having a flat aligner holder supporting the flat aligner; A linear guide interposed between the linear movement table and the support table; And a driving device for linearly moving the linear movement table. The device of claim 1, wherein the image information acquisition device includes an illumination device, and the lamp provided in the illumination device is installed such that its length direction is parallel to the plane of the wafer surface. Wafer edging characterized in that Lee defect inspection device.