Processing equipment

Abstract

To provide an optical system which can be used for holding tables with different diameters.SOLUTION: A processing device which is used when calculating the center position of one surface of a disc-like wafer and performs prescribed processing on the outer peripheral part of the wafer comprises: a holding unit; a processing unit; and an imaging unit which is arranged above the holding unit and images the outer peripheral part of the wafer. The imaging unit comprises: a camera part; a light-emitting unit which includes a light source; and at least three reflecting units which can radiate light from the light source upward. The processing device images at least three spots of the outer peripheral part of the wafer with the imaging unit by sequentially irradiating the outer peripheral part of the wafer that has the larger diameter than the holding table and protrudes to the outer side in the radial direction of the holding table when being suction-held by the holding table with light from the light source from each reflecting unit by adjusting the position of each reflecting unit in the imaging unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a processing apparatus that is used when calculating the center position of one surface of a disk-shaped wafer and performs predetermined processing on the outer peripheral portion of the wafer.

Background Art

[0002] In a disk-shaped wafer having a device region in which a plurality of devices are formed and an outer peripheral surplus region surrounding the device region on the front surface side, a region on the back surface side corresponding to the device region is ground to form a circular recess, and after leaving a ring-shaped reinforcing portion in the region corresponding to the outer peripheral surplus region, a processing method of dividing the wafer into device units is known (see, for example, Patent Document 1).

[0003] When dividing a wafer into device units according to this processing method, usually, first, it is necessary to remove the ring-shaped reinforcing portion. Therefore, a processing apparatus has been proposed that specifies the center position of the surface of the wafer and accurately cuts and removes the ring-shaped reinforcing portion based on this center position (see, for example, Patent Documents 2 and 3).

[0004] In the processing apparatus described in Patent Document 3, in order to specify the center position of the surface of the wafer, a truncated cone is provided on the bottom side rather than the holding surface, and a holding table having a smaller diameter than the wafer is used. The truncated cone is inclined 45 degrees with respect to the horizontal plane and has an annular inclined surface that functions as a mirror surface on the side surface.

[0005] A light source such as an LED (Light Emitting Diode) is provided on the side of the truncated cone. Above the inclined surface, a camera capable of imaging reflected light is provided, and the light irradiated from the light source is reflected upward by the inclined surface and imaged by the camera.

[0006] To calculate the center position of the wafer surface using this frustocone, first, a recess corresponding to the device area formed by grinding is fitted into the holding table, and the wafer is held in place by suction on the holding table. At this time, the outer edge of the wafer extends beyond the outside of the holding table.

[0007] Next, light is shone from the side onto the side of the frustum, and reflected light from the inclined surface is shone onto the outer edge of the wafer, and the outer edge is imaged using a camera. In particular, by rotating the chuck table, three different locations on the outer edge of the wafer are imaged with the camera.

[0008] Since the center position (coordinates) on the holding surface of the holding table is known, the center position (center coordinates) of the wafer surface can be calculated based on the positions (coordinates) of three points on the edge obtained by imaging three locations on the outer periphery.

[0009] However, wafers come in various outer diameters, such as 6 inches (approximately 150 mm), 8 inches (approximately 200 mm), and 12 inches (approximately 300 mm), and the diameter of the circular recess formed on the back side of the wafer varies depending on the wafer diameter. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Publication No. 2007-19461 [Patent Document 2] Japanese Patent Publication No. 2014-60224 [Patent Document 3] Japanese Patent Publication No. 2020-43186 [Overview of the project] [Problems that the invention aims to solve]

[0011] Therefore, in order to hold the recesses of wafers of various diameters by suction, a holding table with a diameter corresponding to the wafer diameter is required. Consequently, in optical systems using frustocones, different sized frustocones are required depending on the outer diameter of the holding table, which creates the problem of increased replacement effort.

[0012] This invention has been made in view of the aforementioned problems, and aims to provide an optical system that can irradiate the outer periphery of a wafer held by a holding table with light, and that can be used with holding tables of different diameters. [Means for solving the problem]

[0013] According to one aspect of the present invention, a processing apparatus used to calculate the center position of one face of a disc-shaped wafer and to perform a predetermined processing on the outer periphery of the wafer comprises a holding unit for holding the wafer, a processing unit for processing the wafer, and an imaging unit for imaging the outer periphery of the wafer held by the holding unit, wherein the holding unit has a disc-shaped holding table for suction holding the wafer, a rotating shaft connected to the holding table for rotating the holding table, and a drive unit for rotating the rotating shaft, and the imaging unit has a camera unit, a light-emitting unit provided below the camera unit and including a light source, and The present invention provides a processing apparatus comprising: at least three reflective units fixed to the rotation axis and positioned on the outer periphery of the holding table so as to be separated from each other along the circumferential direction of the holding table, each having a pair of opposing inclined surfaces, and capable of irradiating light from the light source upward through the pair of inclined surfaces; wherein by adjusting the position of each reflective unit in the imaging unit, light from the light source is sequentially irradiated from each reflective unit onto the outer periphery of the wafer, which has a larger diameter than the holding table and protrudes radially outward from the holding table when held by the holding table, thereby imaging at least three locations on the outer periphery of the wafer with the imaging unit.

[0014] Preferably, the at least three reflective units include, when a first holding table having a first diameter is used as the holding table in the holding unit, at least three first reflective units capable of irradiating light from the light source onto the outer periphery of a first wafer that protrudes radially outward from the first holding table when held by the first holding table and has a diameter larger than the first diameter, and when a second holding table having a second diameter larger than the first diameter is used as the holding table in place of the first holding table in the holding unit, at least three second reflective units capable of irradiating light from the light source onto the outer periphery of a second wafer that protrudes radially outward from the second holding table when held by the second holding table and has a diameter larger than the second diameter.

[0015] Preferably, the holding unit further includes an annular auxiliary table provided on the outer periphery of the holding table, the auxiliary table including through holes for irradiating the outer periphery of the wafer with light reflected by each reflection unit.

[0016] Preferably, the pair of inclined surfaces of each reflective unit include a first mirror surface and a second mirror surface that are inclined at 45 degrees with respect to a plane perpendicular to the longitudinal direction of the reflective unit on which the pair of inclined surfaces are provided, so as to irradiate light from the light source upward. Furthermore, preferably, the light-emitting unit is positioned directly below the annular trajectory traced by the outer of the pair of inclined surfaces by rotating the axis of rotation. [Effects of the Invention]

[0017] A holding unit of a processing apparatus according to one aspect of the present invention has at least three reflective units, each fixed to the rotation axis of the holding table and arranged on the outer periphery of the holding table so as to be separated from each other along the circumferential direction of the holding table. Each reflective unit has a pair of opposing inclined surfaces, and light incident on each reflective unit from a light source can be irradiated upward through this pair of inclined surfaces.

[0018] The outer peripheral portion of the wafer held by the holding unit is imaged by the imaging unit. For example, when a first holding table having a first diameter is attached to the holding unit and the first wafer is sucked and held by the first holding table, the outer peripheral portion of the first wafer is imaged using three reflection units to specify the coordinates of three points on the edge of the first wafer.

[0019] On the other hand, when a holding table having a diameter larger than the first diameter is attached to the holding unit and a wafer having a diameter larger than the first wafer is sucked and held by the holding table, the coordinates of three points on the edge of the large-diameter wafer are specified without using a reflection unit.

[0020] In this way, when using holding tables of different sizes, it is possible to specify the coordinates of the outer peripheral edges of wafers of different diameters simply by selecting whether or not to use at least three reflection units. Therefore, an optical system that can be used for holding tables of different diameters can be provided.

[0021] Furthermore, compared to the case where a dedicated truncated cone corresponding to the diameter of the holding table is attached for each holding table of different sizes, the labor required for replacing the truncated cone can be eliminated.

Brief Description of the Drawings

[0022] [Figure 1] It is a perspective view of a laser processing apparatus. [Figure 2] FIG. 2(A) is a perspective view of the front side of the wafer unit, and FIG. 2(B) is a perspective view of the back side of the wafer. [Figure 3] It is an enlarged perspective view of the holding unit. [Figure 4] It is a partial cross-sectional side view of the holding unit. [Figure 5] It is a partial cross-sectional side view showing a state of imaging the outer peripheral portion of the wafer. [Figure 6] It is a partial cross-sectional side view showing a state of imaging the outer peripheral portion of a large-diameter wafer. [Figure 7]Figure 7(A) is a top view of a holding unit, etc., equipped with a chuck table having a first diameter, and Figure 7(B) is a top view of a holding unit, etc., equipped with a chuck table having a second diameter. [Figure 8] This is a partial cross-sectional side view showing a reflective unit according to the third embodiment. [Figure 9] This is an enlarged view of the retaining unit in a modified example. [Figure 10] This is a partial cross-sectional side view showing the imaging process of the outer edge of a wafer. [Figure 11] This is a partial cross-sectional side view showing the imaging of the outer edge of a large-diameter wafer. [Modes for carrying out the invention]

[0023] An embodiment of one aspect of the present invention will be described with reference to the attached drawings. Figure 1 is a perspective view showing an example of the configuration of a laser processing apparatus (processing apparatus) 2. The laser processing apparatus 2 includes a base 4 that supports each structure.

[0024] The base 4 includes a rectangular parallelepiped base 6 and a wall portion 8 extending upward at the rear end of the base 6. A disc-shaped chuck table (first holding table) 10 is positioned above the base 6. The chuck table 10 holds the disc-shaped wafer (first wafer) 11 to be processed by suction.

[0025] Here, the wafer 11 will be described with reference to Figures 2(A) and 2(B). The wafer 11 has a single-crystal substrate formed of a semiconductor material such as silicon. However, the single-crystal substrate is not limited to silicon, and may be formed of compound semiconductors such as silicon carbide (SiC) or gallium nitride (GaN), or of other materials.

[0026] As shown in Figure 2(A), multiple division lines 13 are set in a grid pattern on the surface (one side) 11a of the wafer 11. A device 15 is formed in each rectangular region demarcated by the multiple division lines 13.

[0027] Device 15 may be, for example, an IC (Integrated Circuit), MEMS (Micro Electro Mechanical Systems), or an LED (Light Emitting Diode), but there are no particular restrictions on the type, size, number, or arrangement of device 15.

[0028] In the radial direction of the wafer 11, an annular outer peripheral surplus region 19 exists outside the device region 17 where multiple devices 15 are formed. The outer peripheral surplus region 19 is a substantially flat region where no devices 15 are formed.

[0029] In Figure 2(A), for convenience, the boundary 17a between the device region 17 and the outer peripheral excess region 19 is shown with a dashed line; however, the boundary 17a is not actually displayed on the wafer 11. Furthermore, a notch 11c indicating the crystal orientation of the single-crystal substrate is formed on the outer periphery of the wafer 11.

[0030] As shown in Figure 2(B), a circular recess 21 is formed on the back surface 11b side of the wafer 11 by grinding a circular region corresponding to the device region 17. For example, the wafer 11 in the device region 17 is thinned to a thickness of approximately 50 μm.

[0031] An annular projection 23 is formed on the outside of the circular recess 21, surrounding the periphery of the circular recess 21. The annular projection 23 is the area that remained without being ground down during the formation of the circular recess 21, and is an annular region corresponding to the outer peripheral excess region 19.

[0032] The diameter of the wafer 11 is, for example, 8 inches (approximately 200 mm). The thickness of the annular protrusion 23 is the same as the thickness of the wafer 11 before grinding, for example, approximately 725 μm, but the thickness of the annular protrusion 23 is appropriately determined according to the diameter of the wafer 11. The width of the annular protrusion 23 in the radial direction of the wafer 11 is, for example, approximately 3.0 mm.

[0033] The annular projection 23 functions as a reinforcing portion of the wafer 11 on which the circular recess 21 is formed. By providing the annular projection 23, damage to the wafer 11 during transport can be prevented compared to the case where the back surface 11b is uniformly thinned without the annular projection 23.

[0034] After forming a circular recess 21 on the back surface 11b side, a circular tape 25 with a larger diameter than the wafer 11 is attached to the back surface 11b side of the wafer 11. The tape 25 is made of a resin that is substantially transparent to light in the visible light band at least.

[0035] The tape 25 has a laminated structure consisting of an adhesive layer (glue layer) made of an adhesive resin such as an ultraviolet-curing resin, and a base material layer made of resin. The back surface 11b of the wafer 11 is attached to the center of the tape 25 in a manner that conforms to the shape of the circular recess 21.

[0036] One side of a metal annular frame 27 is attached to the outer periphery of the tape 25. In this way, a wafer unit 29 is formed in which the wafer 11 is supported by the annular frame 27 via the tape 25.

[0037] Figure 2(A) is a perspective view of the front surface 11a side of the wafer unit 29, and Figure 2(B) is a perspective view of the back surface 11b side of the wafer 11 with the tape 25 and annular frame 27 omitted. The wafer unit 29 is held in place by suction on the chuck table 10 via the tape 25.

[0038] Figure 3 is an enlarged perspective view of the holding unit 12 of the first embodiment, including the chuck table 10, and Figure 4 is a partial cross-sectional side view of the holding unit 12. As shown in Figure 4, the chuck table 10 has a disc-shaped frame 14a made of non-porous ceramics.

[0039] A disc-shaped recess is formed on the upper surface of the frame 14a. A porous plate 14b made of porous ceramics is fixed to this recess. Grooves and holes are formed at the bottom of the recess to transmit negative pressure to the porous plate 14b.

[0040] When negative pressure is applied from a suction source 16 such as an ejector, negative pressure is generated on the upper surface of the porous plate 14b through the grooves and holes of the frame 14a. The upper surfaces of the frame 14a and the porous plate 14b function as holding surfaces 10a that suction and hold the wafer unit 29.

[0041] The wafer 11 is positioned on the chuck table 10 such that its circular recess 21 fits onto the upper part of the chuck table 10, which includes the holding surface 10a, via the tape 25. The lower part of the chuck table 10 is detachably fixed to a disc-shaped table base 18.

[0042] The chuck table 10 is selected to be of an appropriate size according to the size of the wafer 11 to be held by suction (more specifically, the diameter of the circular recess 21 of the wafer 11), and is mounted on the table base 18. The upper part of a cylindrical rotating shaft 20 is connected to the lower part of the table base 18.

[0043] A portion of the rotating shaft 20 corresponds to the rotor of an electrically driven motor and is supported by a X-axis moving plate 40 (described later) via a bearing (not shown). A cylindrical drive unit 22 for rotating the rotating shaft 20 is provided around the rotating shaft 20.

[0044] The drive unit 22 corresponds to the stator of an electrically driven motor. The rotating shaft 20 and the drive unit 22 constitute a DC motor. However, the rotating shaft 20 and the drive unit 22 may be other types of motors, such as an AC motor.

[0045] When power is supplied to the drive unit 22, the chuck table 10, which is connected to the rotating shaft 20 via the table base 18, rotates around the center 20a of the rotating shaft 20. The drive unit 22 is equipped with a rotation angle sensor (not shown), such as a rotary encoder, for detecting the rotation angle of the chuck table 10.

[0046] Multiple clamping units 24, each gripping an annular frame 27, are arranged at approximately equal intervals along the circumferential direction of the chuck table 10 on its outer circumference. The base end of each clamping unit 24 is fixed to the table base 18.

[0047] The chuck table 10, table base 18, rotating shaft 20, drive unit 22, and four clamp units 24 constitute the holding unit 12. The chuck table 10 is replaced as appropriate depending on the diameter of the wafer 11 to be held by suction.

[0048] Four reflective units (first reflective units) 26 are arranged on the outer circumference of the table base 18 at approximately equal intervals, spaced apart from each other along the circumferential direction of the chuck table 10. The base end of each reflective unit 26 is fixed to the rotation axis 20 via the table base 18 at a position different from that of the clamp unit 24.

[0049] Now, with reference to Figure 5, the reflective unit 26 will be described in detail. The reflective unit 26 has metal arms 28 whose longitudinal direction 28a protrudes along the radial direction of the table base 18. Each arm 28 is positioned on the outer periphery of the chuck table 10 in such a manner that it protrudes outward beyond the outer periphery of the chuck table 10.

[0050] A first metal reflective block 30, which has a thickness in the Z-axis direction greater than that of the arm 28, is provided at the tip of the arm 28 in the longitudinal direction 28a. The outer surface of the first reflective block 30 in the longitudinal direction 28a is a vertical plane (plane perpendicular to the longitudinal direction 28a) 30a that is perpendicular to the longitudinal direction 28a.

[0051] In contrast, the inner surface of the first reflective block 30 in the longitudinal direction 28a is a plane (inclined surface 30b) that is inclined at a predetermined angle with respect to the vertical plane 30a. In this embodiment, the inclined surface 30b is inclined at 45 degrees with respect to the vertical plane 30a such that its lower end is located further out than its upper end in the longitudinal direction 28a.

[0052] The inclined surface 30b includes a first mirror surface 30c formed by mirror finishing. Alternatively, the first mirror surface 30c may be provided by fixing a mirror to the inclined surface 30b instead of performing mirror finishing.

[0053] An inverted pyramidal through-hole 28b is formed at the base end of the arm portion 28. At least a portion of the through-hole 28b is located outside the outer circumference of the holding surface 10a in the longitudinal direction 28a, and is located directly below the outer circumference 11d of the wafer 11 that is held by suction on the holding surface 10a.

[0054] A second metal reflective block 34, which has a thickness in the Z-axis direction greater than that of the arm 28, is provided on the lower surface side of the base end of the arm 28. An opening 34a is formed at the tip of the second reflective block 34 in the longitudinal direction 28a.

[0055] On the table base 18 side of the opening 34a of the second reflective block 34, there is a plane (inclined surface 34b) located directly below the through hole 28b and positioned to face the inclined surface 30b in the longitudinal direction 28a.

[0056] The inclined surface 34b is tilted in the same direction as the inclined surface 30b, by a predetermined angle with respect to the vertical plane 30a. In this embodiment, the inclined surface 34b is tilted 45 degrees with respect to the vertical plane 30a in the same direction as the inclined surface 30b.

[0057] Furthermore, the inclined surface 34b includes a second mirror surface 34c formed by mirror finishing. Alternatively, the second mirror surface 34c may be provided by fixing a mirror to the inclined surface 34b instead of mirror finishing.

[0058] When the rotation axis 20 is rotated, the chuck table 10, table base 18, arm 28, etc., rotate together as a single unit. A light-emitting unit 32, including a light source 32a such as an LED, is provided directly below a region corresponding to one point in the annular region formed by the trajectory of the inclined surface 30b of the first reflective block 30.

[0059] Light 32b emitted from the light-emitting unit 32 passes sequentially through the first mirror surface 30c and the second mirror surface 34c (i.e., a pair of inclined surfaces 30b and 34b) and the through hole 28b, and is emitted upward from the through hole 28b. This light 32b is used when the outer periphery 11d (particularly the outer edge 11e) of the wafer 11 held by the holding surface 10a is imaged by the camera unit 64, which will be described later.

[0060] In this embodiment, the case in which four reflection units 26 are provided on the holding unit 12 has been described. However, in order to image at least three locations on the outer peripheral portion 11d of the wafer 11, it is sufficient to provide at least three reflection units 26 on the holding unit 12.

[0061] The four (at least three) reflective units 26, the light-emitting unit 32, the camera unit 64, etc., constitute the imaging unit 36 ​​(i.e., the optical system). Now, returning to Figure 1, the other components of the laser processing apparatus 2 will be described.

[0062] The aforementioned drive unit 22 is supported by a rectangular X-axis movable plate 40. The aforementioned light-emitting unit 32 is fixed to one of the four corners of the X-axis movable plate 40. The X-axis movable plate 40 is slidably supported by a pair of X-axis guide rails 42 that are arranged substantially parallel to the X-axis direction.

[0063] A nut portion (not shown) is provided on the lower surface of the X-axis moving plate 40, and a screw shaft 44, whose longitudinal portion is arranged along the X-axis direction, is rotatably connected to this nut portion via a ball (not shown). A drive source 46, such as a stepping motor, is connected to one end of the screw shaft 44.

[0064] When the screw shaft 44 is rotated by the drive source 46, the X-axis moving plate 40 moves along the X-axis direction. The X-axis moving plate 40, a pair of X-axis guide rails 42, a nut, a screw shaft 44, a drive source 46, etc. constitute a ball screw type X-axis moving unit 48.

[0065] A pair of X-axis guide rails 42 are fixed to the upper surface of the Y-axis movable plate 50. The Y-axis movable plate 50 is slidably supported by a pair of Y-axis guide rails 52 fixed to the upper surface of the base 6 in a direction substantially parallel to the Y-axis direction.

[0066] A nut portion (not shown) is provided on the lower surface of the Y-axis movable plate 50, and a screw shaft 54, whose longitudinal portion is arranged along the Y-axis, is rotatably connected to this nut portion via a ball (not shown). A drive source 56, such as a stepping motor, is connected to one end of the screw shaft 54.

[0067] When the screw shaft 54 ​​is rotated by the drive source 56, the Y-axis moving plate 50 moves along the Y-axis direction. The Y-axis moving plate 50, a pair of Y-axis guide rails 52, a nut, a screw shaft 54, a drive source 56, etc. constitute a ball screw type Y-axis moving unit 58.

[0068] The base end of a cantilevered arm 60 is fixed to the front side surface of the wall 8 in a manner that protrudes above the holding unit 12. Part of a laser processing unit (processing unit) 62 for processing wafers 11, etc., is provided on the arm 60.

[0069] The laser processing unit 62 includes a laser oscillator (not shown) containing a rod-shaped laser medium made of Nd:YAG, Nd:YVO4, etc. The pulsed laser beam emitted from the laser oscillator is irradiated toward the holding surface 10a via a substantially cylindrical light concentrator 62a located at the tip of the arm 60 and above the holding unit 12.

[0070] The laser beam emitted from the light concentrator 62a has a wavelength (for example, 355 nm) that is absorbed by the wafer 11. By rotating the chuck table 10 with the focal point of the laser beam focused by the light concentrator 62a positioned at the boundary 17a, the annular protrusion 23 can be separated from the wafer 11 by ablation.

[0071] As described above, the laser processing unit 62 is used when performing laser processing (a predetermined process) on the outer periphery 11d of the wafer 11. In addition to the laser processing unit 62, the arm 60 is equipped with a camera unit 64.

[0072] The camera unit 64 includes a substantially cylindrical head portion 64a located at the tip of the arm 60 and above the holding unit 12. The head portion 64a is provided with a light-gathering lens (not shown) and the like. The light-emitting unit 32 described above is provided below the head portion 64a.

[0073] The head unit 64a can either capture the light 32b that has been emitted from the light-emitting unit 32 and then reflected by the reflection unit 26, or it can directly capture the light 32b emitted from the light-emitting unit 32 without passing through the reflection unit 26.

[0074] The camera unit 64 includes an image sensor (not shown) such as a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor or a CCD (Charge-Coupled Device) image sensor. The light 32b captured from the head unit 64a is photoelectrically converted by the image sensor and stored as image information in the memory device (not shown) of the laser processing apparatus 2.

[0075] Image information is displayed as an image on, for example, a touch panel 68 located on the front of the housing 66 of the laser processing device 2. The touch panel 68 functions as a display device for displaying images to the operator, and also functions as an input device for the operator to perform predetermined operations and inputs.

[0076] The operation of the holding unit 12, suction source 16, imaging unit 36, X-axis movement unit 48, Y-axis movement unit 58, laser processing unit 62, touch panel 68, etc., is controlled by the control unit 70.

[0077] The control unit 70 is composed of a computer that includes, for example, a processor (processing unit) represented by a CPU (Central Processing Unit), main memory such as DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), and ROM (Read Only Memory), and auxiliary memory such as flash memory, a hard disk drive, and a solid-state drive.

[0078] The auxiliary storage device stores software, including a predetermined program. The functions of the control unit 70 are realized by operating the processing unit and other components according to this software.

[0079] Next, referring to Figure 5, the procedure for calculating the center position 11a1 (see Figure 2(A)) of the surface 11a of the wafer 11 will be described. Figure 5 is a partial cross-sectional side view showing the imaging of the outer periphery 11d of the wafer 11.

[0080] In order to hold the back surface 11b of the wafer 11 by suction, a chuck table 10 is used which has a first diameter 10b that is smaller than the diameter of the wafer 11 and corresponds to the diameter of the circular recess 21 of the wafer 11.

[0081] First, the circular recess 21 of the wafer 11 is fitted onto the upper part of the chuck table 10 via the tape 25. Next, the annular frame 27 (not shown in Figure 5) is clamped by the clamp unit 24, and the back surface 11b of the circular recess 21 is held in place by the holding surface 10a using negative pressure.

[0082] Since the wafer 11 has a diameter larger than the first diameter 10b, the outer periphery 11d of the wafer 11, which is held by suction on the holding surface 10a, protrudes radially outward from the chuck table 10. In this way, the wafer 11 is held by the holding unit 12.

[0083] Subsequently, the X-axis movement unit 48, the Y-axis movement unit 58, and the drive unit 22 are operated to adjust the position of one reflective unit 26 relative to the head unit 64a and the light-emitting unit 32.

[0084] Specifically, the rotation angle of one reflective unit 26 and the positions of the X-axis movable plate 40 and the Y-axis movable plate 50 are adjusted so that the head portion 64a is positioned directly above the through hole 28b of one reflective unit 26, and the light-emitting unit 32 is positioned directly below the inclined surface 30b of the one reflective unit 26.

[0085] Then, by irradiating the outer periphery 11d of the wafer 11 with light 32b from the first reflection unit 26 and imaging the outer periphery 11d with the camera unit 64, a first image is obtained that includes the region obscured by the wafer 11 and the region not obscured by the wafer 11.

[0086] Next, the rotation axis 20 is rotated by approximately 90 degrees, and light 32b is irradiated onto the outer periphery 11d of the wafer 11 from the second reflection unit 26, while the outer periphery 11d is imaged by the camera unit 64 to obtain a second image.

[0087] Next, the rotation axis 20 is rotated approximately 90 degrees further, and light 32b is irradiated onto the outer periphery 11d of the wafer 11 from the third reflection unit 26, while the outer periphery 11d is imaged by the camera unit 64, thereby obtaining a third image.

[0088] In this embodiment, light 32b is sequentially irradiated from each reflection unit 26 to image three different locations on the outer periphery 11d of the wafer 11, and then predetermined image processing such as edge detection is performed by the first program stored in the control unit 70.

[0089] The first program, for example, performs binarization on the first to third images and then performs edge detection to obtain one coordinate point corresponding to the outer edge 11e in each of the first to third images, i.e., a total of three points.

[0090] The coordinates of the three points are defined with the center position (coordinate) 10c (see Figure 4) of the holding surface 10a as the origin. Note that the center position 10c of the holding surface 10a and the center position 11a1 of the surface 11a of the wafer 11 do not usually coincide perfectly, but are offset.

[0091] By utilizing known methods described in Patent Document 3, etc., the center position 11a1 of the surface 11a can be calculated based on the center position 10c of the holding surface 10a and the coordinates of three points corresponding to the outer edge 11e.

[0092] A second program for calculating the center position 11a1 of the surface 11a is stored in the control unit 70. Although the above description described an example of imaging three locations on the outer periphery 11d, imaging at least three locations on the outer periphery 11d is sufficient.

[0093] For example, by capturing images from four or more locations and selectively using appropriate images after excluding those that could not be captured properly for some reason, it is possible to obtain the coordinates of three points corresponding to the outer edge 11e and calculate the center position 11a1.

[0094] The imaging unit 36, excluding the four reflection units 26, is also used when imaging the outer periphery 31d of a wafer (second wafer) 31 that is larger in diameter than wafer 11. Figure 6 is a partial cross-sectional side view showing the imaging of the outer periphery 31d of wafer 31, which is larger in diameter than wafer 11.

[0095] The diameter of wafer 31 is, for example, 12 inches (approximately 300 mm), which is larger than the diameter of wafer 11 (8 inches). Like wafer 11, wafer 31 also has a circular recess 41 formed on its back surface 31b.

[0096] When holding the back surface 31b of the wafer 31 by suction, a chuck table (second holding table) 80 having a second diameter 80b corresponding to the diameter of the circular recess 41 of the wafer 31 is mounted on the table base 18 instead of the chuck table 10. Note that the second diameter 80b is larger than the first diameter 10b of the chuck table 10.

[0097] The chuck table 80, table base 18, rotating shaft 20, drive unit 22, and four clamping units 24 also constitute the holding unit 12. The structure of the chuck table 80 is substantially the same as that of the chuck table 10, so a detailed explanation is omitted.

[0098] To image the outer periphery 31d of the wafer 31, first, the circular recess 41 of the wafer 31 is fitted onto the upper part of the chuck table 80 via the tape 25. Next, the annular frame 27 (not shown in Figure 6) is clamped with the clamp unit 24, and the back surface 31b of the circular recess 41 is held in place by suction from the holding surface 80a using negative pressure.

[0099] Since the wafer 31 has a larger diameter than the second diameter 80b, when it is held by suction on the holding surface 80a, the outer periphery 31d of the wafer 31 protrudes radially outward from the chuck table 80.

[0100] After the holding unit 12 holds the wafer 31, the X-axis movement unit 48 and the Y-axis movement unit 58 are operated to position the light-emitting unit 32 directly below the head unit 64a. Then, when the outer periphery 31d is imaged with the camera unit 64, a fourth image is obtained that includes the area obscured by the wafer 31 and the area not obscured by the wafer 31.

[0101] As shown in Figure 6, when imaging the outer periphery 31d of the wafer 31, the light 32b is directly irradiated onto the outer periphery 31d of the wafer 31 without using the reflection unit 26. Next, the rotation axis 20 is rotated by approximately 90 degrees to directly irradiate the outer periphery 31d with the light 32b, and the camera unit 64 images the outer periphery 31d to obtain a fifth image.

[0102] Next, the rotation axis 20 is rotated approximately 90 degrees further to directly irradiate the outer periphery 31d of the wafer 31 with light 32b, and the outer periphery 31d is imaged with the camera unit 64 to obtain a sixth image. Of course, more than four locations on the outer periphery 31d may also be imaged.

[0103] In this manner, light 32b is sequentially irradiated onto the outer periphery 31d of the wafer 31 without passing through each reflection unit 26, and images are taken of three different locations on the outer periphery 31d. After image processing and other steps, the center position (not shown) of the surface 31a is calculated.

[0104] Thus, in this embodiment, when using chuck tables 10 and 80 of different sizes, the coordinates of the outer edges 11e and 31e of wafers 11 and 31 of different diameters can be determined simply by selecting whether or not to use at least three reflection units 26.

[0105] Therefore, it is possible to provide an optical system that can be used with chuck tables 10 and 80 of different diameters. Furthermore, compared to attaching a dedicated frustum of cone corresponding to the diameter of each chuck table 10 and 80 of different sizes, the effort required to change the frustum of cone can be reduced.

[0106] In the first embodiment, when the chuck table 10 is viewed from above, the through hole 28b is located inward from the light-emitting unit 32 in the radial direction of the table base 18.

[0107] However, if the inclined surfaces 30b and 34b are tilted 45 degrees in the opposite direction to the example in Figure 5, a through hole 28b is formed directly above the inclined surface 34b, and the light-emitting unit 32 is positioned radially inward from the through hole 28b in the table base 18.

[0108] (Second Embodiment) Next, a second embodiment will be described with reference to Figures 7(A) and 7(B). Figure 7(A) is a top view of a holding unit 12, etc., to which a chuck table 10 having a first diameter 10b is attached.

[0109] In Figure 7(A), the outer edge 11e of the wafer 11, which is held by suction on the back surface 11b at the holding surface 10a, is shown by a dashed line. As shown in Figure 7(A), the outer edge 11e is located directly above the through holes 28b of the four reflection units 26.

[0110] In the example shown in Figure 7(A), four clamp units 24 are arranged at approximately equal intervals along the circumferential direction of the table base 18, four reflective units 26 are arranged at approximately equal intervals, and furthermore, four reflective units (second reflective units) 86 are arranged at approximately equal intervals.

[0111] The base end of the reflective unit 86 is fixed to the rotation axis 20 via a table base 18, similar to the reflective unit 26. The reflective unit 86 also includes an arm 28, a first reflective block 30, and a second reflective block 34, similar to the reflective unit 26.

[0112] In other words, the reflective unit 86 also has an inclined surface 30b including a first mirror surface 30c and an inclined surface 34b including a second mirror surface 34c, and the first mirror surface 30c and the second mirror surface 34c enable light 32b to be irradiated from the light-emitting unit 32 to the head portion 64a.

[0113] However, in the longitudinal direction 28a, the distance A2 from the center position 10c of the holding surface 10a (i.e., the center 20a of the rotation axis 20 (see Figure 4)) to the through hole 88 of the reflective unit 86 is longer than the distance A1 from the center position 10c to the through hole 28b of the reflective unit 26 in the longitudinal direction 28a.

[0114] Figure 7(B) is a top view of a holding unit 12, etc., in which a chuck table 80 having a second diameter 80b is attached in place of the chuck table 10. In Figure 7(B), the outer edge 31e of the wafer 31, which is held by suction on the back surface 31b side of the holding surface 80a, is shown by a dashed line.

[0115] As shown in Figure 7(B), the outer edge 31e of the wafer 31 is located directly above the through-holes 88 of the four reflection units 86. Therefore, the light 32b emitted from the light-emitting unit 32 passes through a pair of inclined surfaces (inclined surfaces 30b, 34b) in each reflection unit 86 and irradiates the outer edge 31d of the wafer 31.

[0116] The coordinates of three points on the outer edge 31e of the wafer 31 are defined with the center position (coordinate) 80c of the holding surface 80a as the origin. The center position (not shown) of the surface 11a of the wafer 31 is calculated based on the center position 80c and the coordinates of the three points corresponding to the outer edge 11e.

[0117] In order to calculate the respective center positions of surfaces 11a and 31a, the imaging unit 36 ​​only needs to have at least three reflection units 26 and at least three reflection units 86.

[0118] In the second embodiment, when using chuck tables 10 and 80 of different sizes, the coordinates of the outer edges 11e and 31e of wafers 11 and 31 of different diameters can be determined by using at least three reflective units 26 and at least three reflective units 86, respectively.

[0119] By the way, in the second embodiment, we described a case in which a wafer 11 with a diameter of 8 inches is imaged using the reflection unit 26 and a wafer 31 with a diameter of 12 inches is imaged using the reflection unit 86. However, the diameters of wafers 11 and 31 are not limited to this example.

[0120] Furthermore, the outer periphery of the smallest diameter wafer can be imaged using the reflection unit 26, the outer periphery of wafers of intermediate diameters can be imaged using the reflection unit 86, and the outer periphery of the largest diameter wafer can be imaged without using the reflection units 26 and 86.

[0121] For example, the imaging unit 36 ​​may be configured to image a wafer 11 with a diameter of 6 inches using the reflection unit 26, image a wafer 31 with a diameter of 8 inches using the reflection unit 86, and image the outer periphery of a wafer with a diameter of 12 inches without using the reflection units 26 and 86.

[0122] (Third Embodiment) Next, a third embodiment will be described with reference to Figure 8. Figure 8 is a partial cross-sectional side view showing a reflective unit 90 according to the third embodiment. One reflective unit 90 has both through holes 28b and 88.

[0123] The second reflective block 34 is slidably connected to the arm portion 28 along the longitudinal direction 28a. The second reflective block 34 is positioned such that the second mirror surface 34c is located directly below the through hole 28b or the through hole 88.

[0124] The second reflective block 34 may be moved manually by an operator, or it may be moved automatically by a control unit 70 controlling a ball screw type moving mechanism to move it to a predetermined position.

[0125] By providing at least three reflective units 90 at different positions along the circumferential direction of the table base 18, the functions of both reflective units 26 and 86 can be implemented in a single reflective unit 90.

[0126] (Modifications) Next, modifications will be described using Figures 9 to 11. Although Figures 9 to 11 show modifications to the first embodiment, these modifications are also applicable to the second and third embodiments.

[0127] Figure 9 is an enlarged view of the holding unit 12 according to a modified example. Figure 10 is a partial cross-sectional side view showing the imaging of the outer periphery 11d of the wafer 11. Figure 11 is a partial cross-sectional side view showing the imaging of the outer periphery 31d of a wafer 31 which has a larger diameter than the wafer 11.

[0128] In the modified version of the chuck table 10, an annular auxiliary table 14c, having a larger outer diameter than the chuck table 10, is integrally provided with the frame 14a on its outer circumference.

[0129] The upper surface of the auxiliary table 14c includes a substantially flat, annular outer upper surface 14c1 that is substantially parallel to the X-Y plane. The outer upper surface 14c1 is located lower than the holding surface 10a. In this embodiment, the outer upper surface 14c1 is located lower than the holding surface 10a by a length corresponding to the depth of the circular recess 21 of the wafer 11.

[0130] Therefore, as shown in Figure 11, even when a wafer 31 with a larger diameter than wafer 11 is placed on the chuck table 10, the outer peripheral portion 31d of the wafer 31 is supported by the outer upper surface 14c1, thereby preventing the wafer 31 from bending and allowing the wafer 31 to be held in place by suction.

[0131] The annular inner upper surface 14c2, located inside the outer upper surface 14c1, is inclined such that it becomes lower as it moves from the radial outside to the inside of the frame 14a. A cylindrical through hole 14d is formed in the region including the boundary 14c3 between the outer upper surface 14c1 and the inner upper surface 14c2.

[0132] As shown in Figure 10, the through-hole 14d is located above the through-hole 28b of the reflection unit 26, and the light 32b reflected by the reflection unit 26 passes through the through-hole 14d and is irradiated onto the outer periphery 11d of the wafer 11 which is held by attraction on the holding surface 10a.

[0133] In contrast, when imaging the outer periphery 31d of the wafer 31, as shown in Figure 11, the light 32b is directly irradiated onto the outer periphery 31d of the wafer 31 without using the reflection unit 26.

[0134] In this way, by using a chuck table 10 having an auxiliary table 14c, the wafer 11 can be held by suction with the chuck table 10, and furthermore, a wafer 31 with a larger diameter than the wafer 11 can be held by suction without having to replace it with a chuck table 80 which has a larger diameter than the chuck table 10.

[0135] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the object of the present invention. For example, the outer peripheral portion 11d of the wafer 11, which does not have a circular recess 21 formed thereon, can be processed in the same manner using the laser processing apparatus 2.

[0136] Incidentally, the same functionality as described above can also be achieved in a cutting device (processing device) (not shown) that removes the annular protrusions 23, etc., by performing edge trimming (i.e., predetermined processing such as cutting) on ​​the outer peripheral portions 11d, 31d of the wafers 11, 31.

[0137] The cutting device has a cutting unit (processing unit) instead of the laser processing unit 62. The cutting unit includes a cylindrical spindle housing whose longitudinal portion is arranged parallel to the Y-axis direction. A portion of a cylindrical spindle is rotatably housed in the spindle housing.

[0138] A rotational drive source, such as a motor, is provided at the base end of the spindle. The tip of the spindle protrudes from the spindle housing. A cutting blade having an annular cutting edge is mounted on the tip of the spindle.

[0139] Furthermore, a head portion 64a of the camera unit 64 is provided at a position adjacent to the tip of the spindle in the X-axis direction. This head portion 64a is fixed to the spindle housing.

[0140] The cutting apparatus has a ball screw type cutting feed unit that moves the spindle housing along the Z-axis. The cutting feed unit is connected to an indexing feed unit that moves the spindle housing along the Y-axis.

[0141] Below the cutting unit, a table base 18, a rotating shaft 20, and a drive unit 22 are provided. A clamp unit 24 and a reflection unit 26 are provided on the table base 18 in the same manner as in the embodiment described above. One of the chuck tables 10 or 80 is mounted on the table base 18 in an interchangeable manner.

[0142] The drive unit 22 is supported by the X-axis moving plate 40. The X-axis moving plate 40 and the like constitute a ball screw type X-axis moving unit (machining feed unit) 48. A light-emitting unit 32 is provided on the upper surface of the X-axis moving plate 40. At least three reflective units 26, the light-emitting unit 32, the camera unit 64, and the like constitute an imaging unit 36.

[0143] Even in cutting equipment, when using chuck tables 10 and 80 of different sizes, the coordinates of the outer periphery 11d and 31d of wafers 11 and 31 of different diameters can be determined simply by selecting whether or not to use at least three reflection units 26, etc.

[0144] Therefore, an optical system can be provided that can be used for chuck tables 10 and 80 of different diameters. Furthermore, compared to attaching a dedicated frustum of cone corresponding to the diameter of each chuck table 10 and 80 of different sizes, the effort required to change the frustum of cone can be reduced. The second and third embodiments, as well as their variations, can also be applied to cutting devices. [Explanation of symbols]

[0145] 2: Laser processing equipment (processing equipment) 4: Base, 6: Base, 8: Wall 10: Chuck table (first holding table) 10a: Holding surface, 10b: First diameter, 10c: Center position 11: Wafer (First wafer) 11a: Front side (one side), 11a1: Center position, 11b: Back side 11c: Notch, 11d: Outer perimeter, 11e: Outer edge 12: Holding Unit 13: Planned division line, 15: Device, 17: Device area, 17a: Boundary 14a: Frame, 14b: Porous board 14c: Auxiliary table, 14c1: Outside top surface, 14c2: Inside top surface, 14c3: Boundary 14d: Through hole 16: Suction source 18: Table base 20: axis of rotation, 20a: center 22: Drive unit 19: Outer peripheral excess area, 21: Circular recess, 23: Annular protrusion 24: Clamp Unit 25: Tape, 27: Ring frame, 29: Wafer unit 26: Reflection unit (first reflection unit) 28: Arm portion, 28a: Longitudinal direction, 28b: Through hole 30: First reflective block, 30a: Vertical plane, 30b: Inclined surface, 30c: First mirror surface 31: Wafer (Second wafer) 31a: Front surface (one side), 31b: Back surface, 31d: Outer periphery, 31e: Outer edge 32: Light-emitting unit, 32a: Light source, 32b: Light 34: Second reflecting block, 34a: Aperture, 34b: Inclined surface, 34c: Second mirror surface 36: Imaging Unit 40:X-axis direction moving plate 41: Circular recess 42: X-axis guide rail, 44: Screw shaft, 46: Drive source 48: X-axis movement unit 50: Y-axis moving plate 52: Y-axis guide rail, 54: Screw shaft, 56: Drive source 58: Y-axis movement unit 60: Arm 62: Laser processing unit (processing unit), 62a: Focuser 64: Camera unit, 64a: Head unit 66: Cabinet 68: Touch panel 70: Control Unit 80: Chuck table (second holding table) 80a: Holding surface, 80b: Second diameter, 80c: Center position 86: Reflection unit (second reflection unit), 88: Through hole 90: Reflective Unit A1,A2:Distance

Claims

1. A processing apparatus used to calculate the center position of one side of a disc-shaped wafer, and which performs a predetermined processing on the outer periphery of the wafer, A holding unit for holding the wafer, A processing unit for processing the wafer, An imaging unit for imaging the outer periphery of the wafer held by the holding unit, Equipped with, The holding unit is, A disc-shaped holding table for suction holding the wafer, A rotating shaft connected to the holding table for rotating the holding table, A drive unit that rotates the rotating shaft, It has, The imaging unit is, Camera section, A light-emitting unit including a light source is provided below the camera unit, Each of the following reflecting units is fixed to the rotation axis and positioned on the outer circumference of the holding table so as to be separated from each other along the circumferential direction of the holding table, and each has a pair of opposing inclined surfaces, and is capable of irradiating light from the light source upward through the pair of inclined surfaces, It has, A processing apparatus characterized by adjusting the position of each reflection unit in the imaging unit so that light from the light source is sequentially irradiated from each reflection unit onto the outer periphery of the wafer, which has a larger diameter than the holding table and extends radially outward from the holding table when held by the holding table, and imaging at least three locations on the outer periphery of the wafer with the imaging unit.

2. The at least three reflective units are, When a first holding table having a first diameter is used as the holding table in the holding unit, at least three first reflective units are provided, each capable of irradiating light from the light source onto the outer periphery of a first wafer that protrudes radially outward from the first holding table when held by the first holding table and has a diameter larger than the first diameter, When a second holding table having a second diameter larger than the first diameter is used in the holding unit instead of the first holding table, at least three second reflective units are provided, each capable of irradiating light from the light source onto the outer periphery of the second wafer, which protrudes radially outward from the second holding table when held by the second holding table and has a diameter larger than the second diameter. The processing apparatus according to claim 1, characterized by including the following:

3. The holding unit further includes an annular auxiliary table provided on the outer periphery of the holding table, The processing apparatus according to claim 1 or 2, characterized in that the auxiliary table includes through holes for irradiating the outer periphery of the wafer with light reflected by each reflection unit.

4. The processing apparatus according to any one of claims 1 to 3, characterized in that the pair of inclined surfaces of each reflective unit include a first mirror surface and a second mirror surface that are inclined at 45 degrees with respect to a plane perpendicular to the longitudinal direction of the reflective unit on which the pair of inclined surfaces are provided, so as to irradiate light from the light source upward.

5. The processing apparatus according to any one of claims 1 to 4, characterized in that the light-emitting unit is provided directly below the annular trajectory traced by the outer of the pair of inclined surfaces by rotating the rotation axis.

Images