JP2011027974A - Imaging optical system and processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging optical system that appropriately obtains the outline of an object to be imaged, which is a transparent body with respect to visible light, such as a sapphire substrate, and to provide a processing apparatus by which an object to be processed, such as a sapphire substrate, is aligned using the imaging optical system. <P>SOLUTION: The imaging optical system 110 includes first and second cylindrical lenses 111 and 112 whose light refracting directions intersect each other; a mask 113 that permits the passage of only reflection light from a predetermined area where reflection light passed through the second cylindrical lens 112 form an imaging line L; an imaging lens 114 that forms an image from reflection light passed through the mask 113 from an object M to be imaged; and an imaging element 115 provided in the image forming position of the image forming lens 114. The aperture size NA1 of the first cylindrical lens 111 is greater than the aperture size NA2 of the second cylindrical lens 112. The object M to be imaged is imaged while the condensing point of the first cylindrical lens 111 is aligned to the height of the surface of the object M. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging optical system for imaging an imaging object such as a semiconductor wafer and a processing apparatus including the imaging optical system.

  In a semiconductor device manufacturing process, there is a demand for cutting an optical device wafer in which a gallium nitride compound semiconductor is stacked on the surface of a sapphire substrate, along a planned division line called street. Optical devices (light emitting diodes, laser diodes, etc.) obtained by cutting an optical device wafer along a street are widely used in electrical equipment.

  In general, as a cutting device for cutting a semiconductor wafer, a device using a cutting blade or a laser is known. In such a cutting apparatus, a workpiece is stuck on the surface of a protective tape (transparent or translucent tape) mounted on an annular support frame having an opening in the center, and the support frame is attached to the chuck table in this state. Retained. The workpiece held on the chuck table is cut along the street after the street is detected by the alignment means.

  However, if the work piece is placed at a position deviated from the center of the annular support frame, or the work piece has an irregular shape, the alignment means and the work piece held on the chuck table are appropriate. Therefore, there is a possibility that an alignment error may occur, and the machining may not be performed with an appropriate cutting stroke.

  In order to solve the above problem, a processing apparatus having a function of recognizing the outline of a flat workpiece such as a semiconductor wafer has been proposed (for example, see Patent Document 1). In such a processing apparatus, prior to cutting the semiconductor wafer, the contour of the semiconductor wafer fixed to the support frame is imaged by the imaging unit, and the contour of the semiconductor wafer is recognized based on the image information captured by the imaging unit. Then, the X and Y coordinates of the outline of the semiconductor wafer are obtained with the center of the support frame as the origin, the X direction length and the Y direction length of the street formed on the semiconductor wafer are obtained, and the support frame and the semiconductor wafer Find the center deviation. Alignment corresponding to the center deviation of the support frame and the semiconductor wafer is performed, and an appropriate machining stroke corresponding to the X-direction length and the Y-direction length of the street is calculated, and a machining process is performed based on the calculated stroke.

JP 2006-12901 A

  However, if the imaging object is an optical device wafer that is transparent and thin with respect to visible light such as a sapphire substrate, it is difficult to recognize the contour of the imaging object (wafer) with the existing imaging optical system. However, there is a problem that the outline of the imaging object cannot be grasped.

  The present invention has been made in view of these facts, and the main technical problem thereof is to appropriately grasp the contour even if the object is a transparent object with respect to visible light such as a sapphire substrate. An imaging optical system capable of achieving the above will be provided. It is another object of the present invention to provide a processing apparatus capable of aligning a workpiece such as a sapphire substrate using an imaging optical system.

  The imaging optical system of the present invention includes a first cylindrical lens that is disposed opposite to an imaging object and refracts reflected light incident from the imaging object in the X direction, and a Y direction in which the light refraction direction is orthogonal to the X direction. A second cylindrical lens on which the reflected light that has passed through the first cylindrical lens is incident, and a predetermined region that becomes an imaging line of the reflected light that has passed through the second cylindrical lens. A mask that allows only reflected light of the image to pass through, an imaging lens that forms an image of reflected light from the imaging object that has passed through the mask, and the imaging that is provided and imaged at an imaging position of the imaging lens A first numerical aperture of the first cylindrical lens is equal to a second numerical aperture of the second cylindrical lens. And moving the imaging object and the first cylindrical lens relatively in the X direction in a state where the focal point of the first cylindrical lens is adjusted to the surface height of the imaging object. It is characterized by.

  With such a configuration, the condensing point of the first cylindrical lens is imaged in accordance with the surface of the imaging object, and the reflection surface is deviated from the focusing point in the optical axis direction outside the edge of the imaging object. The amount of light changes greatly with the edge of the imaging object as a boundary, and even if the imaging object is a workpiece such as a sapphire substrate that is transparent to visible light, edge detection can be reliably performed.

  A machining apparatus according to the present invention includes a chuck table that holds a workpiece having a flat plate shape, and moves the chuck table from a holding place where the workpiece is held by the chuck table to a machining area. A moving mechanism for moving the chuck table and the processing unit relative to each other, a processing unit for processing the workpiece held on the chuck table, and the workpiece held on the chuck table as the imaging target An imaging optical system, and recognizes the shape of the workpiece from a captured image of the workpiece captured via the imaging optical system, and holds the workpiece held on the chuck table based on the shape recognition result. The workpiece and the processing unit are aligned.

  According to the present invention, since the shape of the workpiece is recognized from the captured image of the workpiece captured via the imaging optical system, the workpiece can be a workpiece such as a sapphire substrate that is transparent to visible light. Even if it exists, edge detection can be performed reliably. Therefore, by using the shape recognition result of the work piece held on the chuck table, the work piece held on the chuck table and the processing unit can be accurately aligned even with a workpiece such as a sapphire substrate. can do.

  The processing apparatus according to the present invention is characterized in that the imaging optical system is disposed on a path through which the moving mechanism transports the chuck table from the holding place to a processing region.

  According to the present invention, it is possible to recognize the shape of the workpiece while the moving mechanism moves the chuck table from the holding place to the machining area, and after the workpiece has moved to the machining area, the workpiece is moved. Compared with the case of starting the shape recognition work, the machining start time can be shortened.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging optical system which can grasp | ascertain the outline of the imaging target object which is a transparent body with respect to visible lights, such as a sapphire board | substrate, can be provided. Moreover, according to this invention, the processing apparatus which can position workpieces, such as a sapphire board | substrate, using an imaging optical system can be provided.

It is a block diagram of the imaging optical system which concerns on embodiment of this invention. (A) The figure which shows the optical system seen from the X direction shown in FIG. 1, (b) The figure which shows the optical system seen from the Y direction shown in FIG. It is a figure which shows embodiment of the cutting device which concerns on this invention, and is an external appearance perspective view of a cutting device. It is the external appearance perspective view which looked at the processing apparatus shown in FIG. 3 from the opposite side to the state shown in FIG. It is a block diagram of the moving mechanism of the chuck table of a processing apparatus, and a laser beam irradiation unit (processing unit) main body. It is a partial perspective view of the processing apparatus for demonstrating the installation place of a shape recognition mechanism. It is the schematic diagram which looked at the processing apparatus for demonstrating the positional relationship of a holding | maintenance place, a shape recognition mechanism, and a process area | region from the upper side. 3 is a perspective view of a workpiece assembly H in which a plurality of sapphire workpieces are fixed to an annular frame. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a perspective view showing the overall configuration of the imaging optical system according to the present embodiment. 2A is a side view of the imaging optical system viewed from the X direction shown in FIG. 1, and FIG. 2B is a side view of the imaging optical system viewed from the Y direction shown in FIG.

  The imaging optical system 110 according to the present embodiment includes a first cylindrical lens 111 that refracts light only in one direction, and a first cylindrical lens 111 that is arranged so that the light refraction direction is orthogonal to the first cylindrical lens 111. A second cylindrical lens 112, a mask 113 having an opening that defines an imaging range, an imaging lens 114 that forms an image of reflected light from an imaging target that has passed through the opening 113 a of the mask 113, and an imaging lens 114 And an image sensor 115 arranged at the image forming position. Moreover, although not shown in figure, the measurement light source which irradiates illumination light from the upper surface side of an imaging target object and illuminates an imaging target object uniformly is provided.

In the present embodiment, a sapphire substrate (sapphire work) that is thin plate-like and is transparent with respect to visible light will be described as an example of an imaging object. However, a glass substrate (quartz: SiO ₂ ), an LT substrate (tantalic acid) The present invention can also be applied to other plate-like transparent substrates such as lithium: LiTaO ₃ , transparent wavelength region 270 to 5,500 nm). Further, not only a transparent body but also a semiconductor wafer made of a non-transparent body can be used as an imaging object.

  As shown in FIG. 2B, the first cylindrical lens 111 is a plano-convex cylindrical lens that refracts light only in the X direction shown in FIG. 1, and has a first numerical aperture NA1. . As the first numerical aperture NA1 of the first cylindrical lens 111 is higher, the resolution in the thickness direction of the imaging target M (the Z direction orthogonal to the X and Y directions) is higher, so the edge position of the thinner workpiece is also increased. Can be detected. For example, by setting the first numerical aperture NA1 to about 0.3 to 0.4, the edge of a workpiece having a thickness of several tens of μm can be detected.

  The second cylindrical lens 112 is constituted by a plano-convex cylindrical lens that refracts light only in the Y direction orthogonal to the X direction shown in FIG. 1, and has a first numerical aperture NA1 as shown in FIG. Has a small second numerical aperture NA2. When the first numerical aperture NA1 is 0.3 to 0.4, the second numerical aperture NA2 of the second cylindrical lens 12 can be set to 0.02 to 0.03. Increasing the numerical aperture of the second cylindrical lens 112 increases the resolution, and decreasing it increases the imaging range (Y direction). When the second numerical aperture NA2 is set to 0.02 to 0.03, the second cylindrical lens 112 has a Y-direction resolution of about 50 to 100 μm.

  The first numerical aperture NA1 needs to be increased to some extent in order to narrow the depth of focus in the Z direction, and the second numerical aperture NA2 needs to be decreased to some extent in order to widen the imaging range in the Y direction. There is. Therefore, by making the second numerical aperture NA2 smaller than the first numerical aperture NA1, the depth of focus in the Z direction can be narrowed to increase the edge determination accuracy, and a sufficiently long imaging range is ensured in the Y direction. it can.

  The mask 113 is disposed between the convex surface of the second cylindrical lens 112 and the imaging lens 114. As shown in FIG. 2A, the reflected light emitted from the convex surface of the second cylindrical lens 112 intersects at a position away from the convex surface of the second cylindrical lens 112 by a predetermined distance. A mask 113 is disposed in this intersecting region. The numerical aperture is determined by the aperture range of the mask 113 and the focal lengths of the first and second cylindrical lenses 111 and 112. The mask 113 limits the reflected light from the imaging object M. In FIG. 1, only the opening 113a of the mask 113 is shown.

  The imaging lens 114 images the reflected light from the imaging line L that has passed through the mask 113 on the imaging element 115. The arrangement and aperture of the imaging lens 114 are set so that long reflected light in the Y direction from the imaging line L that has passed through the mask 113 is incident. As the imaging lens 114, it is desirable to use a combination lens in which various aberrations are corrected. However, when the aberration does not become a problem, it may be configured as a single lens.

  The imaging element 115 converts the light quantity at each position on the line to the imaging line L imaged by the imaging lens 114 into an electrical signal and outputs it. An electrical signal representing the light amount at each position on the imaging line L output from the imaging element 115 is output to a control unit (not shown).

  The control unit captures the captured image of the imaging line L from the imaging element 115, compares the light amount (luminance) at each position in the line shape with a reference value, and performs edge determination (also referred to as shape recognition) based on the comparison result. I do.

  Imaging is performed in a state where the condensing point of the first cylindrical lens 111 is aligned with the surface of the imaging target M (FIG. 2B) and the imaging line L is on the imaging target M (not including an edge). The line L is imaged on the image sensor 115 and imaged. The light amount (luminance) of the captured image at an arbitrary position on the imaging line L obtained at this time can be used as a reference value. Alternatively, since the light amount (luminance) at each position on the imaging line L is substantially the same, the average luminance can be used as a reference. In any case, the reference value is determined based on the amount of light (brightness) of the image captured in a state where the condensing point of the first cylindrical lens 111 is aligned with the surface of the imaging target M.

  On the other hand, when a part of the imaging line L is outside the edge of the imaging object M (outside the edge), the imaging object M does not exist at the condensing point of the first cylindrical lens 111 outside the edge. For this reason, in a state where the condensing point of the first cylindrical lens 111 is aligned with the surface of the imaging target M, the reflected light from outside the edge included in the imaging line L is out of focus on the imaging element 115. It becomes an image. Under an imaging environment in which the image sensor 115 is irradiated with uniform illumination light, the light amount (luminance) of the blurred image is significantly lower than that of the focused image. In particular, since the first cylindrical lens 111 has a first numerical aperture NA1 that is a high numerical aperture, if the first cylindrical lens 111 slightly deviates in the optical axis direction from the condensing point of the first cylindrical lens 111, the first cylindrical lens 111 is coupled to the image sensor 115. The image to be imaged is an image out of focus. Therefore, if the control unit detects an image whose light amount (luminance) is lower than the reference value by a predetermined value or more from the captured image of the imaging line L, the corresponding portion of the imaging line L corresponding to the pixel position constituting the image is an edge. It can be determined that it is outside.

  In the imaging optical system 110 according to the present embodiment configured as described above, the surface of the imaging object M and the plane of the first cylindrical lens 111 are opposed to each other, and the condensing point of the first cylindrical lens 111 is imaged. An image of the imaging line L is imaged on the imaging element 115 in a state of matching the surface of the object M, and the imaging is performed. A range in which the imaging object M and the imaging optical system 110 are relatively moved in the X direction while maintaining the position of the first cylindrical lens 111 in the optical axis direction, and the imaging object M is reliably included up to the outer periphery in the X direction. Scan with. When scanning for one line in the X direction is completed, the line is shifted by one line in the Y direction and similarly scanned in the X direction. Scanning in the Y direction is performed within a range that reliably includes the outer periphery of the imaging target M in the Y direction.

  In the present embodiment, the first cylindrical lens 111 having sufficient resolution (first numerical aperture NA1) with respect to the thickness of the thin plate-like imaging object M is used. For this reason, as illustrated in FIG. 2B, in the state where the condensing point of the first cylindrical lens 111 is aligned with the surface of the imaging target M, the captured image luminance becomes a reference value, but the imaging target When the surface is slightly deviated from the condensing point of the first cylindrical lens 111 in the thickness direction of the imaging target M, which is the optical axis direction, the captured image corresponding to the imaging position is blurred and the luminance is predetermined from the reference value. Lower than the value.

  Therefore, the captured image obtained as described above has the edge of the imaging object M as a boundary, the captured image is blurred outside the edge, and the luminance is uniformly lower than the reference value by a predetermined value or more. The controller can reliably detect the edge region by determining the luminance of each pixel in the line direction for each line of the captured image of the imaging line L.

  Further, according to the present embodiment, the condensing point of the first cylindrical lens 111 is imaged in accordance with the surface of the imaging object M, and the reflection surface from the focusing point to the optical axis outside the edge of the imaging object M. Since edge detection is performed using the fact that the image is shifted in the direction, edge detection can be reliably performed even if the imaging object M is highly transparent with respect to the wavelength of the measurement light source.

  Next, an embodiment of a processing apparatus including the imaging optical system 110 configured as described above will be described in detail with reference to the accompanying drawings. In the following description, a laser processing apparatus is exemplified, but the present invention can also be applied to a processing apparatus that cuts a workpiece using a cutting blade.

First, a sapphire workpiece W (workpiece) will be briefly described as an example of a thin plate-type transparent workpiece that is generally difficult to image.
FIG. 8 is a perspective view of a workpiece assembly H in which a plurality of sapphire workpieces are fixed to an annular frame. The sapphire workpiece W is formed in a substantially disc shape, and is partitioned into a plurality of regions by division lines arranged in a lattice pattern on the surface of the sapphire substrate, and the optical device 63 is formed in the partitioned regions. Yes. Further, the sapphire workpiece W is supported by the annular frame 65 via the sticking tape 64 and is placed on the placement plate 11 of the processing apparatus 1 while being accommodated in a cassette (not shown) as a workpiece assembly H. The

Hereinafter, the configuration and operation of the processing apparatus according to the present embodiment will be described.
3 is an external perspective view of the processing apparatus according to the embodiment of the present invention, and FIG. 4 is an external perspective view of the processing apparatus shown in FIG. 3 viewed from the side opposite to the state shown in FIG.

  As shown in FIG. 3, the processing apparatus 1 includes a housing 2 that forms a processing space therein, and a laser beam irradiation unit 15 (processing unit) is accommodated in the housing 2 (FIG. 4). 5). The processing apparatus 1 is provided with a chuck table 13 for taking the sapphire workpiece W into the housing 2. FIG. 3 shows a state in which the chuck table 13 is moved to the outside of the housing 2 and waited in front of the housing 2. In this embodiment, the position where the chuck table 13 shown in FIG. This is a holding place for holding the workpiece assembly H (sapphire workpiece W) on the table 13. In front of the housing 2, a placement plate 11 on which a cassette storing sapphire workpieces W is placed adjacent to the chuck table 13 moved to the outside of the housing 2, and the placement plate 11 is moved up and down. Thus, the mounting plate elevating mechanism 4 for adjusting the position of the workpiece assembly H in the height direction is provided.

  In addition, a push-pull arm 6 for delivering the workpiece assembly H between the cassette placed on the placement plate 11 and the pair of guide rails 16 is provided on the front surface portion 2 a of the housing 2. Yes. A pair of guide rails 16 provided on the upper side of the chuck table 13 positioned at the holding place so as to face each other are configured to be separated from each other and accessible. Further, a delivery mechanism 17 that delivers the workpiece assembly H between the pair of guide rails 16 and the chuck table 13 is provided above the pair of guide rails 16. The delivery mechanism 17 is provided with a holding portion 18 that holds the annular frame 65 of the workpiece assembly H at the tip, and has a holding portion lifting mechanism 19 that lifts and lowers the holding portion 18. Furthermore, a touch panel monitor 9 for setting various processing conditions for controlling the processing apparatus 1 is provided on one side surface 2 b of the housing 2.

  FIG. 5 is a view showing a state in which the machining head of the laser beam irradiation unit 15 and the moving mechanism for moving the chuck table 13 in the X direction and the Y direction are extracted. The moving mechanism 20 includes a pair of Y-axis guide rails 22a and 22b arranged in the Y-axis direction, and a Y-axis table 23 provided so as to be movable in the Y-axis direction along the Y-axis guide rails 22a and 22b. Prepare. A nut portion (not shown) is formed on the back side of the Y-axis table 23, and a ball screw 24 is screwed into the nut portion. A drive motor 25 is connected to the end of the ball screw 24, and the ball screw 24 is rotationally driven by the drive motor 25.

  Further, the moving mechanism 20 includes a pair of X-axis guide rails 26a and 26b formed on the Y-axis table 23 in the X-axis direction orthogonal to the Y-axis direction, and the X-axis direction along the X-axis guide rails 26a and 26b. And an X-axis table 27 movably provided. A nut portion (not shown) is formed on the back side of the X-axis table 27, and a ball screw 28 is screwed into the nut portion. A drive motor 29 is connected to the end of the ball screw 28, and the ball screw 28 is rotationally driven by the drive motor 29.

  A chuck table 13 is installed on the X-axis table 27. The chuck table 13 includes a table support unit 31, a wafer holding unit 32 that sucks and holds a workpiece W having a street that is a processing scheduled line provided on the table support unit 31, and a frame holding unit that holds an annular frame 65. 33. Inside the table support portion 31, a suction source for attracting and holding the workpiece W by the wafer holding portion 32 is provided.

  Further, the laser processing head 34 of the laser beam irradiation unit 15 is disposed in the housing 2 at a position above the chuck table 13. The laser beam irradiation unit 15 includes a Z axis adjustment mechanism for a machining head that adjusts the position of the laser machining head 34 in the Z axis direction. The processing apparatus 1 is configured such that the moving mechanism 20 relatively moves the laser beam irradiation unit 15 and the chuck table 13 holding the workpiece assembly H to cut the sapphire workpiece W.

  FIG. 6 is a diagram illustrating an installation place of the shape recognition mechanism 51 that performs imaging and shape recognition of the sapphire workpiece W. The shape recognition mechanism 51 includes the imaging optical system 110 described above. As shown in FIG. 7, the workpiece assembly H fixed to the chuck table 13 is disposed on a path for transporting the workpiece assembly H from the holding place to a processing region for laser processing by the laser beam irradiation unit 15. That is, the shape recognition mechanism 51 is arranged at a position that does not hinder laser processing and before the workpiece assembly H reaches the processing region from the holding place. Thereby, in the process in which the moving mechanism 20 transports the sapphire workpiece W from the holding location to the machining area, it is possible to acquire the contour information of the sapphire workpiece W in the workpiece assembly H fixed to the chuck table 13. When the workpiece W is conveyed to the processing region of the laser beam irradiation unit 15, the shape recognition of the sapphire workpiece W can be finished.

Next, the machining operation by the machining apparatus configured as described above will be described.
A workpiece assembly H loaded on the mounting plate 11 is loaded with a cassette loaded with the workpiece assembly H, and is accommodated at a predetermined position of the cassette placed on the mounting plate 11. It is positioned at a predetermined height by the mounting plate lifting mechanism 4. The workpiece assembly H positioned at a predetermined height is pulled out on the pair of guide rails 16 by the push-pull arm 6 and transferred onto the chuck table 13 by the transfer mechanism 17. If the workpiece assembly H is placed on the chuck table 13, a part of the outer peripheral edge of the annular frame 65 is fixed by the frame holding portion 33, and a suction source (not shown) is activated to operate the sapphire workpiece W. Is sucked and held on the chuck table 13 via the adhesive tape 64. The chuck table 13 holding the workpiece assembly H is moved by the moving mechanism 20 from the holding position where the sapphire workpiece W is held on the chuck table 13 toward the machining area (FIG. 7) inside the housing 2.

  The sapphire workpiece W passes directly under the shape recognition mechanism 51 while moving to the machining area in the housing 2. At this time, the entire sapphire workpiece W is imaged by the imaging optical system 110 provided in the shape recognition mechanism 51.

  An imaging Z-axis adjusting mechanism (not shown) moves the laser processing head 34 in the Z direction so that the condensing point of the first cylindrical lens 111 matches the surface of the sapphire workpiece W. Whether or not the condensing point of the first cylindrical lens 111 is aligned with the surface of the sapphire workpiece W is determined by the control unit based on the luminance of the image formed on the image sensor 115 and controls the imaging Z-axis adjustment mechanism. Then, it may be set in a focused state.

  In this example, the imaging line L that is the imaging range in the Y direction of the imaging optical system 110 is set to be longer than the diameter of the chuck table 13 (FIGS. 6 and 7). Therefore, the imaging of the plurality of sapphire workpieces W is completed only by moving the sapphire workpieces W in the X direction.

  When the chuck table 13 (sapphire workpiece W) passes below the shape recognition mechanism 51, the control unit (not shown) takes an image before the top of the chuck table 13 in the X direction crosses the first cylindrical lens 111. An imaging start instruction is given to the optical system 110. In addition, after the rear end portion of the chuck table 13 in the X direction completely passes through the first cylindrical lens 111, an imaging end instruction is given to the imaging optical system 110. The control unit captures captured images of the plurality of sapphire workpieces W held on the chuck table 13 from the image sensor 115, detects the edge of each sapphire workpiece W, and recognizes the shape of each sapphire workpiece W.

  As described above, the imaging optical system 110 captures an image by matching the condensing point of the first cylindrical lens 111 with the surface of the imaging object M, and the reflection surface is light from the condensing point outside the edge of the imaging object M. Since it shifts in the axial direction, even for a thin plate-shaped workpiece made of a transparent body, the control unit can reliably detect the edge of each sapphire workpiece W simply by comparing the amount of captured image with a reference value. it can.

  The control unit obtains the X and Y coordinates of the outline of each sapphire workpiece W based on the shape recognition result of each sapphire workpiece W, and the X-direction length and Y-direction length of each street formed on the sapphire workpiece W. I ask for it.

  If the chuck table 13 holding the sapphire workpiece W is moved to the machining area (FIG. 7), the control unit drives and controls the moving mechanism 20 based on the shape recognition information of the sapphire workpiece W to adjust the X direction and Perform precise alignment in the Y direction. The optical axis of the laser processing head 34 of the laser beam irradiation unit 15 is precisely aligned with the end of the street that is the processing start point of the sapphire workpiece W to be processed. The machining head 34 of the laser beam irradiation unit 15 is brought close to the sapphire workpiece W to a predetermined distance by a Z axis adjustment mechanism for a machining head (not shown), and the chuck table 3 is moved in the laser machining direction at a predetermined feed speed, thereby The sapphire workpiece W to be processed held on the table 13 is processed along a predetermined street by the laser processing head 34. After machining along a predetermined street, the chuck table 13 is indexed and fed by the street interval, and the above machining operation is performed. Then, if the machining operation is performed along all the streets extending in a predetermined direction of the sapphire workpiece W to be processed, the sapphire workpiece W adjacent in the X direction or the Y direction is set to the same position as the next processing target. Align. When the processing in the X direction or the Y direction is completed for all the sapphire workpieces W, the chuck table 13 is rotated by 90 degrees, and the sapphire workpieces W to be processed first extend in a direction orthogonal to the previously processed direction. Perform machining operations along the street. As a result, all streets formed in the sapphire workpiece W in a lattice shape are processed. The remaining sapphire workpieces W are similarly processed along the street.

  The processing includes groove processing, cutting processing, and the like, but even if the chip is cut, the chip does not fall apart by the action of the adhesive tape 64, and the state of the sapphire work W supported by the annular frame 65 Is maintained.

  When the machining operation is completed along the street formed on the sapphire workpiece W as described above, the chuck table 13 is first returned to the holding place where the workpiece assembly H is sucked and held. The workpiece assembly H sucked and held on the chuck table 13 is again accommodated in the cassette by the delivery mechanism 17, the pair of guide rails 16, and the push-pull arm 6.

  According to the present embodiment, the condensing point of the first cylindrical lens 111 having a high numerical aperture is imaged in accordance with the surface of the workpiece, and the edge is detected from the change in luminance of the captured image. Even if it is a transparent body that transmits light, edge detection can be reliably performed, and the processing unit and the workpiece can be aligned with high accuracy.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  INDUSTRIAL APPLICABILITY The present invention is applicable to an imaging optical system that uses a workpiece such as a sapphire substrate that is transparent and thin with respect to visible light as an imaging target, and a processing apparatus that recognizes the shape of the imaging target and aligns it.

DESCRIPTION OF SYMBOLS 1 Processing apparatus 2 Housing | casing 4 Mounting plate raising / lowering mechanism 6 Push pull arm 11 Mounting plate 13 Chuck table 15 Laser beam irradiation unit (processing unit)
16 Guide rail 17 Delivery mechanism 18 Holding part 19 Holding part raising / lowering mechanism 20 Moving mechanism 22a, 22b Y-axis guide rail 23 Y-axis table 24 Ball screw 25 Drive motor 26a, 26b X-axis guide rail 27 X-axis table 28 Ball screw 29 Drive motor 31 Table support part 32 Wafer holding part 33 Frame holding part 65 Annular frame

Claims (3)

A first cylindrical lens disposed opposite to the imaging object and refracting reflected light incident on the imaging object after being reflected in the X direction;
A second cylindrical lens that is arranged so that a light refraction direction is a Y direction orthogonal to the X direction, and the reflected light that has passed through the first cylindrical lens enters;
A mask that allows only reflected light from a predetermined region to be an imaging line among the reflected light transmitted through the second cylindrical lens, and
An imaging lens that forms an image of reflected light from the imaging object that has passed through the mask;
An imaging element provided at an imaging position of the imaging lens and imaging the imaged imaging line;
The first numerical aperture of the first cylindrical lens is larger than the second numerical aperture of the second cylindrical lens, and the condensing point of the first cylindrical lens is set to the surface height of the imaging object. In this state, the imaging optical system moves the imaging object and the first cylindrical lens relatively in the X direction. A chuck table for holding a flat workpiece,
A moving mechanism for moving the chuck table from a holding place where the workpiece is held by the chuck table to a machining area, and relatively moving the chuck table and the machining unit in the machining area;
A processing unit for processing a workpiece held on the chuck table;
The imaging optical system according to claim 1, wherein the workpiece held on the chuck table is an imaging object.
The shape of the workpiece is recognized from the captured image of the workpiece taken in via the imaging optical system, and the workpiece held on the chuck table and the processing unit are positioned based on the shape recognition result. A processing apparatus characterized by combining. The processing apparatus according to claim 2, wherein the imaging optical system is disposed on a path through which the moving mechanism moves the chuck table from the holding place to a processing region.

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