Method for registering processing device and street detection conditions

Abstract

To provide a processing device which can properly detect a street set in a workpiece on the basis of a key pattern.SOLUTION: A processing device for processing a workpiece comprises a camera which images the workpiece, and a control unit. The control unit comprises: a street detection condition storage part which stores a street detection condition including a reference image corresponding to a key pattern included in the workpiece and position information indicating a physical relation between the key pattern and the street; an image comparison part which compares a photographed image acquired by photographing the key pattern included in the workpiece by the camera with the reference image to calculate the similarity between the photographed image and the reference image; a threshold change part which lowers a preset threshold by a prescribed value when the similarity is less than the preset threshold; and an overwriting part which overwrites the reference image with the photographed image when the similarity is equal to or greater than the changed threshold.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a processing device that processes a workpiece, and a method for registering street detection conditions for detecting streets set on a workpiece in the processing device. [Background technology]

[0002] In the device chip manufacturing process, a wafer is used in which devices are formed in multiple areas partitioned by multiple streets (planned division lines) arranged in a grid pattern. By dividing this wafer along the streets, multiple device chips, each equipped with a device, are obtained. The device chips are mounted on various electronic devices such as mobile phones and personal computers.

[0003] A cutting device is used to divide the wafers. The cutting device is equipped with a chuck table that holds the workpiece and a cutting unit that performs cutting on the workpiece. The cutting unit has a spindle, and an annular cutting blade that cuts the workpiece is attached to the tip of the spindle. The wafer is held on the chuck table and the rotating cutting blade cuts into the wafer, cutting and dividing the wafer.

[0004] In recent years, development has also been underway for a process of dividing a wafer by laser processing using a laser processing device. The laser processing device includes a chuck table for holding the workpiece and a laser irradiation unit for irradiating the workpiece with a laser beam. For example, a laser processed groove is formed along the street by irradiating a laser beam along the street on a wafer held by the chuck table. After that, when an external force is applied to the wafer, the laser processed groove functions as a dividing starting point, and the wafer is divided along the street.

[0005] When dividing a wafer using a processing device such as a cutting device or a laser processing device, it is necessary to identify the positions of the streets set on the wafer and process the wafer along the streets. Therefore, before dividing the wafer, an image of the wafer is captured by a camera and the streets are detected based on the image obtained by capturing the image.

[0006] For example, the streets are detected by performing pattern matching using a characteristic pattern included in the wafer as a landmark (key pattern) (see Patent Document 1). In this method, first, a reference image including the key pattern and position information indicating the positional relationship between the key pattern and the streets are registered in advance in the processing device. Then, when processing the wafer, the key pattern included in the wafer to be processed is captured by a camera, and the captured image is compared with the reference image. As a result, the position of the key pattern included in the wafer is identified, and the positions of the streets set on the wafer are identified based on the above-mentioned position information. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Special Publication No. 3-27043 Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, when processing a workpiece such as a wafer with a processing device, a reference image including a key pattern and street detection conditions including position information indicating the positional relationship between the key pattern and the street are registered in the processing device. For example, the reference image is acquired by capturing an image of an imaging wafer having the same structure as the workpiece to be processed with a camera mounted on the processing device.

[0009] In addition, multiple processing devices may simultaneously perform the same type of processing on the same type of workpiece. In this case, a reference image can be acquired by one processing device and the reference image can be transferred to the other processing devices. This eliminates the need for a process of capturing an image of an imaging wafer and acquiring a reference image in each of the multiple processing devices, and simplifies the work of registering street detection conditions.

[0010] However, the imaging conditions when the imaging wafer is imaged by a camera to obtain a reference image may differ from the imaging conditions when the workpiece to be processed is imaged by a camera to obtain an image. For example, the camera and light source mounted on the processing device may deteriorate over time between the time when the reference image is obtained and the time when the image is obtained, resulting in a difference in shading and brightness between the reference image and the imaged image. In addition, when a reference image transferred from another processing device is registered in the processing device, an image with the same image quality as the reference image may not be obtained when the workpiece is processed due to the characteristic variations of the camera and light source between the processing devices.

[0011] As described above, when the image quality of the reference image and the captured image differs, even if the reference image and the captured image contain the same key pattern, the similarity between the reference image and the captured image decreases. As a result, the key pattern contained in the workpiece may not be detected correctly, making it difficult to detect the streets set on the workpiece. In this case, it is necessary to take a new image of the imaging wafer with a camera and re-register the reference image, which reduces the operating efficiency of the processing device.

[0012] The present invention has been made in consideration of such problems, and has an object to provide a processing device and a method for registering street detection conditions that are capable of appropriately detecting streets set on a workpiece based on a key pattern. [Means for solving the problem]

[0013] According to one aspect of the present invention, there is provided a processing apparatus for processing a workpiece, the processing apparatus comprising: a chuck table for holding the workpiece; a processing unit for processing the workpiece held by the chuck table along streets set in the workpiece; a camera for photographing the workpiece held by the chuck table; and a control unit, the control unit comprising: a street detection condition storage unit for storing street detection conditions including a reference image corresponding to a key pattern included in the workpiece and position information indicating a positional relationship between the key pattern and the street; an image comparison unit for comparing an image obtained by photographing the key pattern included in the workpiece held by the chuck table with the reference image to calculate a similarity between the image and the reference image; a threshold change unit for lowering the threshold by a predetermined value when the similarity is less than a preset threshold; and an overwrite unit for overwriting the reference image with the image when the similarity is equal to or greater than the changed threshold.

[0014] Preferably, the street detection conditions are street detection conditions imported from another processing device. Also, preferably, the processing device further includes a display unit, and the display unit displays the reference image and the captured image, the similarity of which with respect to the reference image is equal to or greater than the changed threshold, before the reference image is overwritten.

[0015] According to another aspect of the present invention, there is provided a method for registering street detection conditions in a processing device, the processing device including a chuck table that holds the workpiece, a processing unit that processes the workpiece held by the chuck table along the streets, and a camera that photographs the workpiece held by the chuck table, the method including: a street detection condition registration step of registering street detection conditions including a reference image corresponding to a key pattern included in the workpiece and position information indicating a positional relationship between the key pattern and the street; an image comparison step of comparing a captured image obtained by photographing the key pattern included in the workpiece held by the chuck table with the reference image to calculate a similarity between the captured image and the reference image; a threshold changing step of lowering the threshold by a predetermined value when the similarity is less than a preset threshold; and an overwriting step of overwriting the reference image with the captured image when the similarity is equal to or greater than the changed threshold.

[0016] Preferably, in the street detection condition registration step, street detection conditions transferred from another processing device are registered as the street detection conditions. Also, preferably, the method for registering street detection conditions further includes, before the overwriting step, a display step of displaying the reference image and the captured image whose similarity to the reference image is equal to or greater than the changed threshold value. Effect of the Invention

[0017] In a processing device and a method for registering street detection conditions according to an aspect of the present invention, when the similarity between a captured image and a reference image is less than a threshold, the threshold is lowered by a predetermined value. Then, when the similarity between the captured image and the reference image is equal to or greater than the changed threshold, the reference image is overwritten with the captured image. This prevents a decrease in the accuracy of pattern matching caused by changes in the imaging conditions, and makes it possible to properly detect streets set on a workpiece based on a key pattern. [Brief description of the drawings]

[0018] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 4(A) is a plan view showing a part of a workpiece, and FIG. 4(B) is a plan view showing a key pattern. [Diagram 5] FIG. 2 is a block diagram showing a control unit. [Figure 6] 13 is a flowchart showing a method for registering street detection conditions. [Figure 7] FIG. 7(A) is an image diagram showing a reference image, FIG. 7(B) is an image diagram showing a captured image, and FIG. 7(C) is a front view showing a display unit that displays the reference image and the captured image. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the present embodiment will be described with reference to the attached drawings. First, an example of the configuration of a processing device according to the present embodiment will be described. FIG. 1 is a perspective view showing a processing device 2. The processing device 2 is a cutting device that performs cutting processing on a workpiece 11. In FIG. 1, the X-axis direction (processing feed direction, left-right direction, first horizontal direction) and the Y-axis direction (indexing feed direction, front-back direction, second horizontal direction) are perpendicular to each other. Also, the Z-axis direction (vertical direction, up-down direction, height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0020] The processing device 2 includes a base 4 that supports and houses each of the components that make up the processing device 2. A rectangular parallelepiped opening 4a is formed at a corner on the front end side of the base 4. A cassette support table 6 that moves (lifts and lowers) along the Z-axis direction by a lifting mechanism (not shown) is provided inside the opening 4a. A cassette 8 capable of housing a plurality of workpieces 11 to be processed by the processing device 2 is mounted on the cassette support table 6. Note that in FIG. 1, only the outline of the cassette 8 is shown by a two-dot chain line.

[0021] 2 is a perspective view showing a workpiece 11. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and has a front surface 11a and a back surface 11b that are generally parallel to each other. The workpiece 11 is partitioned into a plurality of rectangular regions by a plurality of streets (planned division lines) 13 that are arranged in a lattice pattern so as to intersect with each other.

[0022] Devices 15 such as ICs (Integrated Circuits), LSIs (Large Scale Integration), LEDs (Light Emitting Diodes), MEMS (Micro Electro Mechanical Systems) devices, etc. are formed on the front surface 11a side of the areas partitioned by the streets 13. The workpiece 11 is processed by a processing device 2 (see FIG. 1) and divided along the streets 13, thereby manufacturing a plurality of device chips each including a device 15.

[0023] There are no limitations on the material, shape, structure, size, etc. of the workpiece 11. For example, the workpiece 11 may be a wafer (substrate) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass (quartz glass, borosilicate glass, etc.), resin, ceramics, metal, etc. There are also no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15.

[0024] When the workpiece 11 is processed by the processing device 2, the workpiece 11 is supported by an annular frame 17. The frame 17 is made of a metal such as SUS (stainless steel). A cylindrical opening 17a having a diameter larger than that of the workpiece 11 is provided in the center of the frame 17 so as to penetrate the frame 17 in the thickness direction. The workpiece 11 is placed inside the opening 17a.

[0025] Tape 19 is attached to workpiece 11 and frame 17. Tape 19 includes a film-like substrate formed into a circular shape and an adhesive layer (glue layer) provided on the substrate. For example, the substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy-, acrylic-, or rubber-based adhesive. The adhesive layer may be an ultraviolet-curing resin that is cured by irradiation with ultraviolet light.

[0026] When the center of the tape 19 is attached to the back surface 11b side of the workpiece 11 and the outer periphery of the tape 19 is attached to the frame 17, the workpiece 11 is supported by the frame 17 via the tape 19. Then, the workpiece 11, supported by the frame 17, is housed in the cassette 8 (see FIG. 1).

[0027] 1, a transport unit (transport mechanism) 10 that transports a workpiece 11 is provided behind the opening 4a. The transport unit 10 is configured to be movable along the Y-axis direction, and transports the workpiece 11 out of the cassette 8 and into the cassette 8. A gripper 10a that grips a frame 17 is provided at an end of the transport unit 10 on the opening 4a side (cassette 8 side).

[0028] Between the opening 4a and the transport unit 10, there is provided a temporary placement area 12 in which the workpiece 11 carried out from the cassette 8 and the workpiece 11 carried into the cassette 8 are temporarily placed. A pair of guide rails 14 arranged approximately parallel to each other along the Y-axis direction are provided in the temporary placement area 12. The pair of guide rails 14 move toward and away from each other along the X-axis direction, and align the workpiece 11 by sandwiching a frame 17 therebetween.

[0029] A transport unit (transport mechanism) 16 that transports the workpiece 11 is provided near the temporary placement area 12. For example, the transport unit 16 includes a plurality of suction pads that hold the upper surface side of a frame 17 by suction.

[0030] A rectangular parallelepiped opening 4b is provided on the side of the opening 4a, with its longitudinal direction aligned with the X-axis direction. A moving unit (moving mechanism) 18 including a flat moving table 18a is provided inside the opening 4b. The moving unit 18 is, for example, a ball screw type moving mechanism, and moves the moving table 18a along the X-axis direction. In addition, bellows-shaped dust-proof and drip-proof covers 20 that expand and contract along the X-axis direction are provided on both sides of the moving table 18a so as to cover the components of the moving unit 18.

[0031] A chuck table (holding table) 22 for holding the workpiece 11 is provided on the moving table 18a. The upper surface of the chuck table 22 is a flat surface that is approximately parallel to the horizontal direction (XY plane direction) and constitutes a holding surface 22a for holding the workpiece 11. The holding surface 22a is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), and the like provided inside the chuck table 22. In addition, a plurality of clamps 24 for gripping and fixing the frame 17 are provided around the periphery of the chuck table 22.

[0032] The moving unit 18 moves the chuck table 22 together with the moving table 18a along the X-axis direction. The moving unit 18 positions the chuck table 22 between a transfer area A where the workpiece 11 is transferred and a processing area B where the workpiece 11 is processed. A rotation drive source (not shown) such as a motor is connected to the chuck table 22. The rotation drive source rotates the chuck table 22 around a rotation axis that is approximately parallel to the Z-axis direction.

[0033] In the processing area B, a processing unit (cutting unit) 26 that processes the workpiece 11 is provided. An annular cutting blade 28 is attached to the processing unit 26. The processing unit 26 cuts the workpiece 11 by rotating the cutting blade 28 and cutting into the workpiece 11.

[0034] 3 is a perspective view showing the machining unit 26. The machining unit 26 includes a hollow cylindrical housing 30. A cylindrical spindle 32 arranged along the Y-axis direction is accommodated in the housing 30. A tip end (one end side) of the spindle 32 is exposed from the housing 30. A rotation drive source (not shown) such as a motor that rotates the spindle 32 is coupled to a base end (the other end side) of the spindle 32.

[0035] A mount 34 that supports the cutting blade 28 is fixed to the tip of the spindle 32. The mount 34 includes a disk-shaped flange portion 36 and a cylindrical support shaft (boss portion) 38 that protrudes from the center of a surface 36a of the flange portion 36. On the surface 36a side of the outer periphery of the flange portion 36, an annular protrusion 36b that protrudes from the surface 36a is provided along the outer periphery of the flange portion 36. A tip surface 36c of the protrusion 36b is formed generally parallel to the surface 36a. A screw groove 38a is formed on the outer periphery of the support shaft 38.

[0036] An annular cutting blade 28 for cutting the workpiece 11 is attached to the mount 34. The cutting blade 28 includes an annular base 28a made of a metal such as an aluminum alloy, and an annular cutting edge 28b formed along the outer edge of the base 28a. A cylindrical opening 28c penetrating the cutting blade 28 in the thickness direction is provided in the center of the cutting blade 28.

[0037] The cutting blade 28b is formed so as to protrude from the outer peripheral edge of the base 28a toward the outside in the radial direction of the base 28a. For example, the cutting blade 28b includes abrasive grains made of diamond, cubic boron nitride (cBN), or the like, and a binder such as a nickel plating layer that fixes the abrasive grains. There are no limitations on the material of the abrasive grains, the particle size of the abrasive grains, the material of the binder, or the like, and they are appropriately selected according to the material of the workpiece 11, or the like.

[0038] An annular fixing nut 40 for fixing the cutting blade 28 is fastened to the thread groove 38a of the support shaft 38. A cylindrical opening 40a penetrating the fixing nut 40 in the thickness direction is provided at the center of the fixing nut 40. A thread groove corresponding to the thread groove 38a of the support shaft 38 is formed on the inner peripheral surface of the fixing nut 40 exposed inside the opening 40a.

[0039] The cutting blade 28 is attached to the mount 34 so that the support shaft 38 is inserted into the opening 28c. In this state, when the fixing nut 40 is screwed into the thread groove 38a of the support shaft 38 and tightened, the cutting blade 28 is clamped between the tip surface 36c of the flange portion 36 and the fixing nut 40. In this manner, the cutting blade 28 is attached to the tip of the spindle 32. Then, the cutting blade 28 rotates around a rotation axis that is approximately parallel to the Y-axis direction by power transmitted from the rotation drive source via the spindle 32 and the mount 34.

[0040] A moving unit (moving mechanism, not shown) that moves the processing unit 26 along the Y-axis direction and the Z-axis direction is connected to the processing unit 26. For example, the moving unit is a ball screw type moving mechanism including a Y-axis ball screw arranged along the Y-axis direction and a Z-axis ball screw arranged along the Z-axis direction. The moving unit adjusts the position of the cutting blade 28 attached to the processing unit 26 in the Y-axis direction and the Z-axis direction.

[0041] 1, a camera (imaging unit) 42 is provided at a position overlapping with the movement path (between the transport area A and the processing area B) of the chuck table 22. The camera 42 is equipped with an image sensor such as a CCD (Charged-Coupled Devices) sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor, and captures an image of the workpiece 11 held by the chuck table 22. For example, the camera 42 may be a visible light camera equipped with an imaging element that receives visible light and converts it into an electrical signal, or an infrared camera equipped with an imaging element that receives infrared light and converts it into an electrical signal.

[0042] A cleaning unit (cleaning mechanism) 44 for cleaning the workpiece 11 is provided behind the chuck table 22. For example, the cleaning unit 44 includes a spinner table that holds and rotates the workpiece 11, and a nozzle that supplies a cleaning fluid such as pure water toward the workpiece 11 held by the spinner table.

[0043] A transport unit (transport mechanism) 46 is provided above the cleaning unit 44 to transport the workpiece 11 between the chuck table 22 and the cleaning unit 44. For example, the transport unit 46 includes a plurality of suction pads that hold the upper surface side of the frame 17 by suction.

[0044] A support stand 48 is provided behind the processing area B, and a display unit (display section, display device) 50 is mounted on the support stand 48. In addition, an input unit (input section, input device) 52 for inputting various information to the processing device 2 is provided at the front end of the base 4.

[0045] As the display unit 50, various displays are used. As the input unit 52, an operation panel equipped with a plurality of operation keys, a mouse, a keyboard, or the like is used. The processing device 2 may be equipped with a touch panel display that functions as a user interface. In this case, the touch panel display functions as the display unit 50 and the input unit 52. An operator can input various information (processing conditions, street detection conditions, etc.) to the processing device 2 by touching the touch panel display.

[0046] Each of the components constituting the processing device 2 (the cassette support table 6, the transport unit 10, the guide rails 14, the transport unit 16, the moving unit 18, the chuck table 22, the clamps 24, the processing unit 26, the camera 42, the cleaning unit 44, the transport unit 46, the display unit 50, the input unit 52, etc.) is connected to a control unit (control unit, control device) 54. The control unit 54 controls the operation of the processing device 2 by generating and outputting control signals that control the operation of each component of the processing device 2.

[0047] For example, the control unit 54 is configured by a computer. Specifically, the control unit 54 includes a calculation section that performs calculations necessary for the operation of the processing device 2, and a storage section that stores various information (data, programs, etc.) necessary for the operation of the processing device 2. The calculation section includes a processor such as a CPU (Central Processing Unit). The storage section includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory) that function as a main storage device, an auxiliary storage device, etc.

[0048] The workpiece 11 is processed by the above-mentioned processing device 2. Specifically, first, the transport unit 10 moves toward the cassette 8 and grips the end of the frame 17 housed in the cassette 8 with the gripping portion 10a. Then, the transport unit 10 moves away from the cassette 8 along the Y-axis direction. As a result, the workpiece 11 is pulled out of the cassette 8 and placed on the pair of guide rails 14.

[0049] The pair of guide rails 14 approach each other while supporting the frame 17 from below, and sandwich the frame 17. This aligns the position of the workpiece 11. The workpiece 11 is then sucked and held by the transport unit 16, and transported to the chuck table 22 positioned in the transport area A.

[0050] The workpiece 11 is placed on the holding surface 22a of the chuck table 22 via the tape 19. In addition, the frame 17 is fixed by a plurality of clamps 24. In this state, when the suction force (negative pressure) of the suction source is applied to the holding surface 22a, the workpiece 11 is sucked and held by the chuck table 22 via the tape 19. Then, the chuck table 22 holding the workpiece 11 is positioned in the processing area B by the moving unit 18.

[0051] Next, the workpiece 11 is cut by the cutting blade 28 attached to the processing unit 26. Specifically, with the lower end of the cutting blade 28 positioned below the upper surface of the workpiece 11, the chuck table 22 is moved along the X-axis direction while rotating the cutting blade 28 (processing feed). As a result, the chuck table 22 and the processing unit 26 move relatively along the X-axis direction, and the rotating cutting blade 28 cuts into the workpiece 11. As a result, the workpiece 11 is cut linearly.

[0052] When the processing of the workpiece 11 is completed, the workpiece 11 is transported from the chuck table 22 to the cleaning unit 44 by the transport unit 46, and is cleaned by the cleaning unit 44. Then, the cleaned workpiece 11 is transported onto the pair of guide rails 14 by the transport unit 16, and is then held by the gripping portion 10a of the transport unit 10 and stored in the cassette 8.

[0053] When dividing the workpiece 11 along the streets 13 (see FIG. 2) using the processing device 2, it is necessary to cut the cutting blade 28 into the workpiece 11 along the streets 13. Therefore, before cutting the workpiece 11 with the cutting blade 28, an operation is performed in which the workpiece 11 is imaged by the camera 42 and the streets 13 are detected based on the image acquired by imaging. For example, the streets 13 are detected by pattern matching using a characteristic pattern contained in the workpiece 11 as a landmark (key pattern).

[0054] 4(A) is a plan view showing a part of the workpiece 11. In the pattern matching performed in the processing device 2, a characteristic pattern present on the surface 11a side of the workpiece 11 is set as a key pattern. There is no limitation on the pattern set as the key pattern. For example, a predetermined structure (electrodes, wiring, terminals, etc.) included in the device 15, the outline of the device 15, etc. are used as the key pattern. In addition, when a TEG (Test Element Group) for inspecting the device 15 is provided on the street 13, a predetermined structure (electrodes, wiring, terminals, etc.) included in the TEG can also be used as the key pattern.

[0055] 4(B) is a plan view showing key pattern 21. For example, a cross-shaped pattern included in device 15 is set as key pattern 21. It is preferable that the shape of key pattern 21 does not match the shape of other patterns present in the vicinity. For example, a predetermined pattern included in each device 15 is set as key pattern 21. This makes it less likely that a misrecognition will occur in which another pattern is recognized as key pattern 21.

[0056] Next, the detection of the streets 13 using the key pattern 21 will be described in detail. The detection of the streets 13 is performed using the camera 42 and the control unit 54 (see FIG. 1) mounted on the processing device 2. FIG. 5 is a block diagram showing the control unit 54. In addition to a block showing the functional configuration of the control unit 54, FIG. 5 shows blocks showing the camera 42 and the input unit 52.

[0057] The control unit 54 includes a processing unit 60 and a storage unit 80. The processing unit 60 processes information (signals, data, etc.) input from the outside, and generates and outputs various information (signals, data, etc.) to the outside. The storage unit 80 stores information (data, programs, etc.) used for processing in the processing unit 60.

[0058] The processing unit 60 includes a street detection condition input unit 62 to which street detection conditions are input. The street detection conditions are information necessary for detecting the streets 13 (see FIG. 2) set on the workpiece 11, and are registered in advance in the control unit 54 before the processing device 2 (see FIG. 1) starts processing the workpiece 11.

[0059] Specifically, an image corresponding to the key pattern 21 (see FIGS. 4(A) and 4(B)) included in the workpiece 11 is input to the street detection condition input unit 62 as a reference image. The reference image is an image for comparison used in pattern matching, and includes an image of the key pattern 21. For example, the reference image is acquired by capturing an image of an imaging wafer having the same structure as the workpiece 11 with the camera 42. The method of acquiring the reference image will be described in detail later.

[0060] Furthermore, position information indicating the positional relationship between the key pattern 21 and the street 13 is input to the street detection condition input unit 62. For example, the coordinates of the key pattern 21 and the distance d from the key pattern 21 to the street 13 (see FIG. 4(B)) are input as position information to the street detection condition input unit 62. A method for acquiring the position information will be described later in detail.

[0061] The storage unit 80 includes a street detection condition storage unit 82 that stores street detection conditions. Then, the street detection conditions including a reference image and position information indicating the positional relationship between the key pattern 21 and the street 13 are input from the street detection condition input unit 62 to the street detection condition storage unit 82 and stored in the street detection condition storage unit 82. In this way, the street detection conditions are registered in the control unit 54. Note that, when a plurality of types of workpieces 11 having different shapes and positions of the key patterns 21, widths and intervals of the streets 13, etc. are processed by the processing device 2, street detection conditions are selected for each type of workpiece 11 and stored in the street detection condition storage unit 82.

[0062] The processing unit 60 also includes an image input unit 64 to which an image (captured image) acquired by the camera 42 is input. After the street detection conditions are registered in the control unit 54, when the workpiece 11 is processed by the processing device 2, the workpiece 11 held by the chuck table 22 (see FIG. 1) is imaged by the camera 42. Then, the captured image of the workpiece 11 is input from the camera 42 to the image input unit 64.

[0063] The processing unit 60 also includes an image comparison unit 66 that compares the captured image with a reference image. The image comparison unit 66 compares the captured image input to the image input unit 64 with the reference image stored in the street detection condition storage unit 82, and calculates and quantifies the similarity between the two. There is no limitation on the method of calculating the similarity. For example, the image comparison unit 66 uses the captured image and the reference image to calculate the Sum of Squared Difference (SSD), Sum of Absolute Difference (SAD), Normalized Cross Correlation (NCC), or Zero-means Normalized Cross Correlation (ZNCC).

[0064] Then, the image comparison unit 66 compares the similarity between the captured image and the reference image with a threshold value. Specifically, the storage unit 80 includes a threshold value storage unit 84 that stores a preset threshold value. The image comparison unit 66 compares the similarity between the captured image and the reference image calculated by pattern matching with the threshold value stored in the threshold value storage unit 84 to determine whether the similarity is equal to or greater than the threshold value.

[0065] When the similarity between the captured image and the reference image is equal to or greater than a threshold value, the position of the street 13 is identified based on the street detection conditions stored in the street detection condition storage unit 82. In this way, the street 13 set on the workpiece 11 to be processed by the processing device 2 is detected.

[0066] On the other hand, if the similarity between the captured image and the reference image is less than the threshold, the threshold to be compared with the similarity is changed. Specifically, the processing unit 60 includes a threshold changing unit 68, and the result of the determination by the image comparing unit 66 is input to the threshold changing unit 68. Then, if the similarity between the captured image and the reference image is less than the threshold, the threshold changing unit 68 accesses the threshold storage unit 84 and lowers the threshold stored in the threshold storage unit 84 by a predetermined value.

[0067] When the threshold is changed, the image comparison unit 66 compares the similarity between the captured image and the reference image with the changed threshold. If the similarity is equal to or greater than the changed threshold, the reference image stored in the street detection condition storage unit 82 is overwritten with the captured image. Specifically, the processing unit 60 includes an overwriting unit 70, and a result of the determination by the image comparison unit 66 is input to the overwriting unit 70. If the similarity between the captured image and the reference image is equal to or greater than the changed threshold, the overwriting unit 70 accesses the street detection condition storage unit 82 and rewrites the reference image stored in the street detection condition storage unit 82 with the captured image.

[0068] Next, a specific method for registering the street detection conditions in the processing device 2 will be described. Fig. 6 is a flowchart showing the method for registering the street detection conditions. Hereinafter, a specific example of the operation of the control unit 54 and the like will be described with reference to Figs. 5, 6, and the like.

[0069] First, initial conditions of street detection conditions are registered in the processing device 2 (street detection condition registration step, step S1). In the street detection condition registration step, street detection conditions including a reference image corresponding to the key pattern 21 (see FIGS. 4(A) and 4(B)) included in the workpiece 11 and position information indicating the positional relationship between the key pattern 21 and the street 13 are stored in the street detection condition storage section 82 of the control unit 54.

[0070] Specifically, first, an imaging wafer having the same structure as the workpiece 11 is held by a chuck table 22 (see FIG. 1). The imaging wafer includes streets 13, devices 15, and key patterns 21 (see FIGS. 4(A) and 4(B)) like the workpiece 11. Note that the workpiece 11 can also be used as the imaging wafer.

[0071] Next, the chuck table 22 holding the imaging wafer is positioned directly under the camera 42 (see FIG. 1), and the imaging wafer is imaged by the camera 42. The camera 42 images an object present in a predetermined imaging area (imaging field of view) and generates an image of the object. The imaging area of ​​the camera 42 includes a key pattern setting area 42a (see FIG. 4(B)) in which a predetermined pattern to be set in the key pattern is positioned.

[0072] In the street detection condition registration step, the positional relationship between the chuck table 22 and the camera 42 is adjusted so that a predetermined area including the key pattern 21 of the imaging wafer falls within the imaging area of ​​the camera 42. Also, the position, shape and size of the key pattern setting area 42a are set so that the key pattern 21 falls within the key pattern setting area 42a. For example, the position of the key pattern setting area 42a is adjusted so that the center position of the key pattern setting area 42a coincides with the center position of the key pattern 21. When the imaging wafer is imaged by the camera 42 in this state, an image including the key pattern 21 is acquired.

[0073] 7(A) is an image diagram showing a reference image 90. In the reference image 90, the key pattern 21 is displayed at a position that fits within the key pattern setting area 42a. Then, the reference image 90 including the key pattern 21 is input to the street detection condition input unit 62 as a comparison image used for pattern matching.

[0074] Furthermore, the control unit 54 acquires position information indicating the positional relationship between the key pattern 21 and the street 13. For example, the control unit 54 acquires, as position information, coordinates corresponding to the position of the key pattern 21 included in the imaging wafer and a distance between the key pattern 21 included in the imaging wafer and the street 13.

[0075] Specifically, first, the coordinates of the center position of key pattern setting area 42a (see FIG. 4(B)) are obtained. Note that the center of key pattern setting area 42a and the center of key pattern 21 are positioned so as to coincide with each other. Therefore, the coordinates of the center position of key pattern setting area 42a correspond to the coordinates of the center position of key pattern 21. However, the center of key pattern setting area 42a and the center of key pattern 21 do not necessarily have to coincide completely.

[0076] Next, an image of an area (see FIG. 4(B)) of the imaging wafer including the streets 13 and the key pattern 21 is displayed on the display unit 50 (see FIG. 1). Then, the operator of the processing device 2 operates the input unit 52 while referring to the image displayed on the display unit 50, and inputs the center position of the street 13 in the width direction to the processing device 2.

[0077] Thereafter, the control unit 54 calculates the difference between the Y coordinate of the center position of the key pattern setting area 42a and the Y coordinate of the center position of the street 13 specified by the operator. As a result, the distance d (see FIG. 4(B)) from the center position of the key pattern setting area 42a to the center position of the street 13 is specified. Then, the coordinates of the key pattern setting area 42a and the distance d from the key pattern setting area 42a to the street 13 are input to the street detection condition input unit 62 as position information.

[0078] The street detection condition input unit 62 stores the street detection conditions, including the reference image 90 (see FIG. 7(A)) input from the camera 42 and the position information indicating the positional relationship between the key pattern 21 and the street 13, in the street detection condition storage unit 82. In this way, the street detection conditions are registered in the control unit 54.

[0079] In order to improve the processing efficiency, the same type of processing may be performed simultaneously on the same type of workpiece 11 by a plurality of processing devices. In this case, the street detection conditions acquired by one processing device may be transferred to the other processing devices. Specifically, first, in a processing device other than the processing device 2 (a source processing device), the street detection conditions are registered according to the above procedure. Thereafter, the source processing device transmits the street detection conditions to the processing device 2, which is the destination processing device, and the street detection conditions are stored in the street detection condition storage unit 82 of the processing device 2. This omits the imaging of the inspection wafer in the processing device 2, the calculation of the positional relationship between the key pattern 21 and the street 13, and the like, and simplifies the street detection condition registration step.

[0080] Thereafter, the workpiece 11 (see FIG. 2) is processed by the processing device 2 for which the street detection conditions have been registered. At this time, prior to processing of the workpiece 11, the streets 13 of the workpiece 11 are detected by pattern matching. When detecting the streets 13 of the workpiece 11, first, a captured image obtained by capturing an image of the workpiece 11 with the camera 42 is compared with a reference image to calculate a similarity between the captured image and the reference image (image comparison step, step S2).

[0081] Specifically, the workpiece 11 to be processed by the processing device 2 is held by the chuck table 22 (see FIG. 1), and the chuck table 22 is positioned directly below the camera 42 (see FIG. 1). Then, the workpiece 11 is imaged by the camera 42, and a captured image of the workpiece 11 is obtained. FIG. 7(B) is an image diagram showing the captured image 92.

[0082] The captured image 92 is input from the camera 42 to the image input unit 64. Then, the image comparison unit 66 compares the captured image 92 input from the image input unit 64 with the reference image 90 stored in the street detection condition storage unit 82, and calculates the similarity between them. Furthermore, the image comparison unit 66 compares the calculated similarity with the threshold value stored in the threshold storage unit 84.

[0083] Here, when the position of the key pattern 21 (see FIG. 7(A)) included in the reference image 90 and the position of the key pattern 21 (see FIG. 7(B)) included in the captured image 92 are roughly the same, the similarity between the captured image 92 and the reference image 90 is high and the similarity is equal to or greater than the threshold value. On the other hand, when the captured image 92 does not include the key pattern 21 or when the position of the key pattern 21 included in the captured image 92 is shifted, the similarity between the captured image 92 and the reference image 90 is low and the similarity is less than the threshold value. Therefore, when the similarity between the captured image 92 and the reference image 90 is equal to or greater than the threshold value, it can be determined that the key pattern 21 included in the workpiece 11 is positioned in the key pattern setting area 42a of the camera 42.

[0084] If the similarity between the captured image 92 and the reference image 90 is equal to or greater than the threshold value (YES in step S3), the position of the key pattern 21 included in the workpiece 11 and the distance from the key pattern 21 to the street 13 are identified based on the street detection conditions stored in the street detection condition storage unit 82. As a result, the position of the street 13 set in the workpiece 11 is identified, and the street 13 is detected (step S4). Then, the workpiece 11 is cut along the detected street 13 by the cutting blade 28 (see FIGS. 1 and 3).

[0085] On the other hand, if the similarity between the captured image 92 and the reference image 90 is less than the threshold value (NO in step S3), the positional relationship between the chuck table 22 and the camera 42 is changed, and the workpiece 11 is imaged again, and the captured image 92 is compared with the reference image 90 (NO in step S5, step S2). By repeating this operation, it is confirmed whether or not a region corresponding to the reference image 90 (see FIG. 7(A)) exists in the workpiece 11.

[0086] Here, the imaging conditions when the imaging wafer is imaged by the camera 42 to obtain the reference image 90 (see FIG. 7(A)) may differ from the imaging conditions when the workpiece 11 to be processed is imaged by the camera 42 to obtain the captured image 92 (see FIG. 7(B)). For example, the camera 42 and the light source may deteriorate over time between when the reference image 90 is obtained and when the captured image 92 is obtained, resulting in a difference in shading or brightness between the reference image 90 and the captured image 92. In addition, when the reference image 90 transferred from another processing device is registered in the processing device 2, the captured image 92 may not have the same image quality as the reference image 90 when the workpiece 11 is processed due to the characteristic variations of the camera and light source between the processing devices.

[0087] For example, as shown in Figures 7(A) and 7(B), if there is a difference in shading between the key pattern 21 included in the reference image 90 and the key pattern 21 included in the captured image 92, even if the same key pattern 21 is arranged in the same position in the reference image 90 and the captured image 92, the similarity between the reference image 90 and the captured image 92 decreases. As a result, the key pattern 21 included in the workpiece 11 is not detected correctly, and it may become difficult to detect the street 13 set on the workpiece 11.

[0088] Therefore, in this embodiment, if the similarity between all captured images 92 acquired by the camera 42 and the reference image 90 is less than the threshold (YES in step S5), the threshold is lowered by a predetermined value (threshold changing step, step S6). For example, if the initial value of the threshold is a value corresponding to a similarity of 90%, the threshold changing unit 68 changes the threshold to a value corresponding to a similarity of 80%. Then, the image comparing unit 66 compares the similarity between the captured images 92 and the reference image 90 with the changed threshold.

[0089] When the similarity between the captured image 92 and the reference image 90 is equal to or greater than the changed threshold value (YES in step S7), the control unit 54 outputs a control signal to the display unit 50 (see FIG. 1) to display the reference image 90 and the captured image 92. As a result, the reference image 90 and the captured image 92 are simultaneously displayed side by side on the display unit 50 (display step, step S8).

[0090] Fig. 7(C) is a front view showing the display unit 50 displaying the reference image 90 and the captured image 92. For example, as shown in Fig. 7(C), the display unit 50 simultaneously displays an enlarged image of the key pattern 21 included in the reference image 90 and an enlarged image of the key pattern 21 included in the captured image 92 side by side.

[0091] The operator of the processing device 2 refers to the reference image 90 and the captured image 92 displayed on the display unit 50, and confirms that the key pattern 21 contained in the reference image 90 is also contained in the captured image 92. Then, the operator operates the input unit 52 to instruct the processing device 2 to use the captured image 92 as a new reference image. When this instruction is input to the processing device 2, the overwriting unit 70 outputs the captured image 92 input from the image input unit 64 to the street detection condition storage unit 82, and overwrites the reference image 90 stored in the street detection condition storage unit 82 with the captured image 92 (overwriting step, step S9).

[0092] When the reference image 90 is overwritten with the captured image 92, the captured image 92 most recently acquired by the processing device 2 itself that detects the streets 13 and processes the workpiece 11 is used as a reference image for pattern matching thereafter. This suppresses deterioration of the accuracy of pattern matching caused by deterioration over time of the camera 42 and the light source, variation in the characteristics of the camera 42 and the light source among a plurality of processing devices, and the like.

[0093] Furthermore, before the overwriting step, a reference image 90 corresponding to the reference image before overwriting and a captured image 92 corresponding to the reference image after overwriting are displayed side by side on the display unit 50 (display step), and the operator is asked for permission to overwrite the reference image, thereby preventing the overwriting of the reference image from being performed without the operator's knowledge.

[0094] In the image comparison step (step S2), multiple captured images 92 can be obtained while changing the imaging area of ​​the camera 42, and each of the multiple captured images 92 can be compared with the reference image 90. However, when the camera 42 captures an image of the workpiece 11 over a wide range, two or more captured images 92 having a similarity to the reference image 90 equal to or greater than a threshold value may be obtained. In this case, it is preferable to narrow the imaging area of ​​the workpiece 11 captured by the camera 42 and then perform the image comparison step (step S2) again.

[0095] Furthermore, if the similarity between the captured image 92 and the reference image 90 is less than the changed threshold (NO in step S7), the threshold may be further lowered and then the similarity may be compared with the changed threshold. However, if the threshold is changed to a value less than a predetermined lower limit, overwriting of the reference image may be stopped. In this case, a street detection condition registration step is performed and street detection conditions including the latest reference image are registered in the control unit 54.

[0096] As described above, in the processing device 2 according to this embodiment, when the similarity between the captured image 92 and the reference image 90 is less than the threshold, the threshold is lowered by a predetermined value. Then, when the similarity between the captured image 92 and the reference image 90 is equal to or greater than the changed threshold, the reference image 90 is overwritten with the captured image 92. This suppresses a decrease in the accuracy of pattern matching caused by changes in the imaging conditions, and makes it possible to properly detect the streets 13 set on the workpiece 11 based on the key pattern 21.

[0097] In the above embodiment, the processing device 2 (cutting device) has been described as the processing device that processes the workpiece 11, but there is no limitation on the type of processing device according to the present invention. For example, the processing device according to the present invention may be a laser processing device that processes the workpiece 11 by irradiating it with a laser beam.

[0098] The laser processing apparatus includes a chuck table that holds the workpiece 11, a processing unit (laser irradiation unit) that irradiates the workpiece 11 with a laser beam, a camera that captures the workpiece 11, and a control unit. The configurations of the chuck table, camera, and control unit of the laser processing apparatus are similar to those of the chuck table 22 (see FIG. 1), camera 42 (see FIG. 1), and control unit 54 (see FIGS. 1 and 5), respectively.

[0099] The laser irradiation unit includes a laser oscillator and an optical system that guides the laser beam emitted from the laser oscillator to the workpiece 11 held by the chuck table. The laser beam emitted from the laser irradiation unit is focused on the surface or inside of the workpiece 11 by a focusing lens included in the optical system, and laser processing is performed on the workpiece 11. As a result, for example, laser processed grooves are formed along the streets 13 of the workpiece 11.

[0100] In addition, the structure, method, etc. according to this embodiment can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0101] 11 Workpiece 11a surface 11b Back side 13th Street (Planned division line) 15 Devices 17 Frame 17a aperture 19 Tape 21 Key Pattern 2 Processing equipment 4 Foundation 4a,4b opening 6 Cassette Support Stand 8 Cassettes 10 Transport unit (transport mechanism) 10a Grip part 12 Temporary Storage Area 14 Guide rail 16 Transport unit (transport mechanism) 18 Mobile unit (mobile mechanism) 18a Mobile table 20 Dust-proof / water-proof cover 22 Chuck table (holding table) 22a Holding surface 24 Clamp 26 Processing unit (cutting unit) 28 Cutting blade 28a base 28b cutting blade 28c aperture 30 Housing 32 Spindle 34 Mount 36 Flange section 36a surface 36b Convex part 36c Tip surface 38 Support shaft (boss part) 38a Thread groove 40 Fixing nut 40a opening 42 Camera (imaging unit) 42a Key pattern setting area 44 Cleaning unit (cleaning mechanism) 46 Transport unit (transport mechanism) 48 Support stand 50 Display unit (display unit, display device) 52 Input unit (input section, input device) 54 Control unit (control unit, control device) 60 Processing section 62 Street detection condition input section 64 Image input section 66 Image Comparison Section 68 Threshold change unit 70 Overwrite section 80 Storage section 82 Street detection condition memory section 84 Threshold memory unit 90 Reference Images 92 Captured images

Claims

1. A processing device for processing a workpiece, comprising: A chuck table for holding the workpiece; a machining unit that machines the workpiece held by the chuck table along streets set on the workpiece; a camera for photographing the workpiece held by the chuck table; A control unit, The control unit a street detection condition storage unit that stores a reference image corresponding to a key pattern included in the workpiece and a street detection condition including position information indicating a positional relationship between the key pattern and the street; an image comparison unit that compares a captured image obtained by capturing an image of the key pattern included in the workpiece held by the chuck table with the reference image, and calculates a similarity between the captured image and the reference image; a threshold changing unit that, when the similarity is less than a preset threshold, lowers the threshold by a predetermined value; and an overwriting unit that overwrites the reference image with the captured image when the similarity is equal to or greater than the changed threshold.

2. 2. The processing apparatus according to claim 1, wherein the street detection conditions are street detection conditions imported from another processing apparatus.

3. Further comprising a display unit; The processing device according to claim 1 or 2, characterized in that the display unit displays the reference image and the captured image whose similarity to the reference image is greater than or equal to the changed threshold value before the reference image is overwritten.

4. A method for registering street detection conditions for detecting streets set on a workpiece in a processing device, comprising the steps of: the processing device includes a chuck table that holds the workpiece, a processing unit that processes the workpiece held by the chuck table along the street, and a camera that photographs the workpiece held by the chuck table; a street detection condition registration step of registering street detection conditions including a reference image corresponding to a key pattern included in the workpiece and position information indicating a positional relationship between the key pattern and the street; an image comparison step of comparing a captured image obtained by capturing an image of the key pattern included in the workpiece held by the chuck table with the reference image and calculating a similarity between the captured image and the reference image; a threshold changing step of lowering the threshold by a predetermined value when the similarity is less than a preset threshold; and an overwriting step of overwriting the reference image with the captured image when the similarity is equal to or greater than the changed threshold.

5. 5. The method for registering street detection conditions according to claim 4, wherein in said street detection condition registration step, street detection conditions transferred from another processing device are registered as said street detection conditions.

6. 6. The method for registering street detection conditions according to claim 4, further comprising, before the overwriting step, a display step of displaying the reference image and the captured image whose similarity to the reference image is equal to or greater than the changed threshold value.

Images