Processing method of the workpiece

Abstract

To cut a workpiece so that the centers of processed grooves in a width direction on a back surface side and a front side of the workpiece are aligned with each other.SOLUTION: A method of processing a workpiece includes a holding step of holding a front surface side of the workpiece with a holding table having a region formed of a transparent material, and a processed groove forming step of forming a processed groove in the workpiece. The processed groove forming step includes a first imaging step of imaging a processed groove on a back surface side of the workpiece, a second imaging step of imaging the processed groove on the front surface side of the workpiece via the holding table, and a detection step of detecting whether the position of a first center line of the processed groove imaged in the first imaging step and the position of a second center line of the processed groove imaged in the second imaging step match each other within a predetermined plane. In the detection step, when the positions of the first and second center lines do not match each other within the predetermined plane, the processed groove forming step further includes a correcting step of correcting the position of the center of a cutting blade so that the positions of the first and second center lines match each other.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a method for processing a workpiece, in which the workpiece is processed while the front side of the workpiece is held by a holding table having an area formed of a material that is transparent to visible light. [Background technology]

[0002] Device chips are used in electronic devices such as mobile phones and personal computers. Device chips are manufactured by dividing a workpiece such as a silicon wafer on which multiple devices such as ICs (Integrated Circuits), LSIs (Large Scale Integration), and MEMS (Micro Electro Mechanical Systems) are formed on the surface.

[0003] For example, the back side of the workpiece is ground with a grinding device to thin the workpiece to a predetermined thickness, and then the workpiece is cut along each planned division line using a cutting device having a cutting unit and a chuck table, thereby dividing the workpiece into individual device chips.

[0004] However, in recent years, with the diversification of devices, a cutting method has become known in which the surface side on which the device is formed faces downward and is held by suction on a chuck table, and the workpiece is cut along the intended division line (see, for example, Patent Document 1).

[0005] Normally, alignment marks used to detect the positions of the planned dividing lines are formed on the front side of the workpiece. Therefore, when the front side is suction-held by a chuck table and the back side is exposed upward, it is necessary to place a camera unit capable of imaging the workpiece with infrared light above the workpiece and image the front side of the workpiece from the back side.

[0006] In response to this, a cutting machine is known that has a chuck table made of a material that is transparent to visible light and has a camera unit disposed below the chuck table that can capture an image of the workpiece using visible light (see, for example, Patent Document 2).

[0007] By using this cutting device, even when the front surface is held by suction on the chuck table, the front surface of the workpiece can be imaged through the chuck table using visible light, making it possible to align the workpiece without using a camera unit for infrared light.

[0008] By the way, when the workpiece is made of a hard material or is relatively thick, there is a cutting method called step cut, in which the workpiece is cut in stages by making multiple cuts along one planned division line.

[0009] In a typical step cut, first, a chuck table made of porous ceramics or the like is used to suction-hold the back side of the workpiece so that the front side of the workpiece is exposed upward. Next, alignment is performed with a visible light camera unit placed above the workpiece, and the planned division line is positioned approximately parallel to the processing feed direction.

[0010] Then, the workpiece is cut along the planned division line with the first cutting blade to form a first groove of a predetermined depth that does not divide the workpiece, and then, the bottom of the first groove is further cut with a second cutting blade having a blade thickness thinner than the first cutting blade to form a second groove that is narrower than the first groove and reaches the back surface of the workpiece.

[0011] In this way, in step cutting, the workpiece is divided by a first machined groove on the front side and a second machined groove on the back side. However, even if the machined groove is imaged from above the workpiece with a camera unit, the second machined groove located on the back side cannot be imaged, and there is a problem in that it is not possible to confirm whether the center line in the width direction of the first machined groove and the center line in the width direction of the second machined groove coincide with each other. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2006-140341 ​​A [Patent Document 2] JP 2010-87141 A Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in consideration of these problems, and aims to cut a workpiece so that the center line of the width direction of the machined groove on the back side of the workpiece coincides with the center line of the width direction of the machined groove on the front side of the workpiece. [Means for solving the problem]

[0014] According to one aspect of the present invention, there is provided a method for processing a workpiece, the method comprising: a holding step of holding a front side of the workpiece with a holding table having an area formed of a transparent material while exposing a back side of the workpiece; and a machining groove forming step of cutting the workpiece held by the holding table with a cutting blade to form a machining groove in the workpiece, the machining groove forming step comprising: a first cutting groove forming step of forming a first cutting groove having a predetermined depth not reaching the surface with a first cutting blade having a first thickness; a second cutting groove forming step of positioning a second cutting blade having a second thickness in the first cutting groove and forming a second cutting groove along the first cutting groove reaching the surface, thereby dividing the workpiece; and The back side of the workpiece 1. Machining groove In visible light a first imaging step of imaging; Using a second imaging unit positioned below the workpiece The surface side of the workpiece Second The machining groove is formed through the holding table. In visible light a second imaging step of imaging the object captured in the first imaging step; 1. The position of the first center line of the processed groove and the corresponding imaged in the second imaging step Secondand a detection step of detecting whether the position of the first center line and the position of the second center line of the machined groove coincide within a predetermined plane. If the detection step determines that the position of the first center line and the position of the second center line do not coincide within the predetermined plane, the machined groove forming step further includes a correction step of correcting the position of the center of the cutting blade so that the position of the first center line and the position of the second center line coincide.

[0015] According to another aspect of the present invention, there is provided a method for processing a workpiece, the method comprising: a holding step of holding a front side of the workpiece with a holding table having an area formed of a transparent material while exposing a back side of the workpiece; and a machining groove forming step of cutting the workpiece held on the holding table with a cutting blade to form a machining groove in the workpiece, the machining groove forming step including a first machining groove forming step of forming a first machining groove having a predetermined depth that does not reach the front surface with a first cutting blade having a first thickness; a second machining groove forming step of positioning a second cutting blade having a second thickness at the first machining groove to form a second machining groove along the first machining groove that reaches the front surface, thereby dividing the workpiece; and an imaging unit for imaging the workpiece using a third imaging unit arranged below the workpiece. a first imaging step of imaging the first machining groove on the back side of the workpiece with infrared light via the holding table, a second imaging step of imaging the second machining groove on the front side of the workpiece with infrared light via the holding table using the third imaging unit, and a detection step of detecting whether or not the position of the first center line of the first machining groove imaged in the first imaging step and the position of the second center line of the second machining groove imaged in the second imaging step match within a predetermined plane, and if the position of the first center line and the position of the second center line do not match within the predetermined plane in the detection step, the machining groove forming step further includes a correction step of correcting the position of the center of the cutting blade so that the position of the first center line and the position of the second center line match.

[0016] Preferably, the second cutting blade has a thickness less than the thickness of the first cutting blade. Effect of the Invention

[0018] In a method for processing a workpiece according to one embodiment of the present invention, the processed groove on the back side of the workpiece is imaged (first imaging process), and the processed groove on the front side of the workpiece is imaged via a holding table (second imaging process).

[0019] Then, it is detected whether the position of the first center line of the processed groove on the back side imaged in the first imaging process and the position of the second center line of the processed groove on the front side imaged in the second imaging process coincide within a specified plane (detection process).

[0020] If the position of the first center line and the position of the second center line do not coincide within a predetermined plane, the position of the center of the cutting blade is corrected so that the position of the first center line coincides with the position of the second center line (correction step). Therefore, in the subsequent cutting, the center of the width direction of the machined groove on the back side of the workpiece can be made to coincide with the center of the width direction of the machined groove on the front side of the workpiece. [Brief description of the drawings]

[0021] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4]FIG. 2 is a partial cross-sectional side view of the chuck table. [Diagram 5] FIG. 5 is an enlarged view of area A in FIG. [Figure 6] FIG. 2 is an enlarged perspective view of a lower imaging unit. [Figure 7] FIG. [Figure 8] FIG. 11 is a diagram showing a first groove forming step. [Figure 9] FIG. 13 is a diagram showing a first imaging step. [Figure 10] FIG. 10(A) is an example of an image including a first processing groove, and FIG. 10(B) is another example of an image including a first processing groove. [Figure 11] FIG. 13 is a diagram showing an additional first groove forming step. [Figure 12] 11A to 11C are diagrams showing a second groove forming step. [Figure 13] FIG. 11 is a diagram showing a second imaging step. [Figure 14] FIG. 14(A) is an example of an image including a second processing groove, and FIG. 14(B) is another example of an image including a second processing groove. [Figure 15] FIG. 11 is a cross-sectional view of the workpiece after an additional second groove forming step. [Figure 16] FIG. 16(A) is a diagram showing the first imaging step, and FIG. 16(B) is a diagram showing the second imaging step. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of a cutting device 2 according to a first embodiment. In Fig. 1, some of the components are shown in a functional block diagram.

[0023] 1, the X-axis direction (machining feed direction), the Y-axis direction (indexing feed direction), and the Z-axis direction (vertical direction) are mutually perpendicular. The X-axis direction is parallel to the +X and -X directions. Similarly, the Y-axis direction is parallel to the +Y and -Y directions, and the Z-axis direction is parallel to the +Z and -Z directions.

[0024] The cutting device 2 includes a base 4 that supports each of the components. An opening 4a is formed in the front (+Y direction) corner of the base 4, and a cassette elevator (not shown) is provided within the opening 4a. A cassette 6 for storing a plurality of workpieces 11 (see FIG. 2) is placed on the upper surface of the cassette elevator.

[0025] The workpiece 11 is, for example, a disk-shaped wafer made of a semiconductor material such as silicon. However, there are no limitations on the material, shape, structure, size, etc. of the workpiece 11. The workpiece 11 may be made of other materials such as semiconductors, ceramics, resins, and metals.

[0026] 2, a plurality of mutually intersecting division lines (streets) 13 are set on the front surface 11a side of the workpiece 11. Each of the plurality of sections partitioned by the plurality of division lines 13 has a device 15 such as an IC, an alignment mark (not shown), and the like formed thereon.

[0027] A tape (dicing tape) 17 having a diameter larger than that of the workpiece 11 is attached to the front surface 11a. The tape 17 has a laminated structure of a base layer and an adhesive layer (glue layer), and is made of a transparent material that is capable of transmitting light of a predetermined wavelength band, such as visible light and infrared light.

[0028] The base layer is made of, for example, polyolefin (PO) etc. The adhesive layer is made of, for example, an adhesive resin such as an ultraviolet (UV) curable acrylic resin etc. The adhesive layer side of the tape 17 is attached to the front surface 11a side.

[0029] A metal annular frame 19 is attached to the outer periphery of the tape 17, and the workpiece 11 is accommodated in the cassette 6 as a workpiece unit 21 supported by the frame 19 via the tape 17. Figure 2 is a perspective view of the workpiece unit 21.

[0030] 1, a rectangular opening 4b is formed behind the opening 4a (in the -Y direction). A disk-shaped chuck table (holding table) 10 is disposed in the opening 4b. An annular frame suction plate (not shown) having a plurality of suction ports formed along the circumferential direction is provided on the outer periphery of the chuck table 10.

[0031] Here, the chuck table 10 and the like will be described in more detail with reference to Fig. 3 to Fig. 6. Fig. 3 is a perspective view of the chuck table 10, and Fig. 4 is a partially sectional side view of the chuck table 10. However, hatching has been omitted in Fig. 4 for the sake of convenience.

[0032] Fig. 5 is an enlarged view of region A in Fig. 4. Fig. 5 shows some of the components in a functional block diagram. The chuck table 10 has a disk-shaped holding member 12. The holding member 12 includes a substantially flat surface 12a and a substantially flat other surface 12b located opposite to the surface 12a.

[0033] The holding member 12 is formed of a transparent material that transmits visible light and infrared light (for example, near-infrared light). The holding member 12 is formed of, for example, quartz glass, borosilicate glass, or soda glass, but may also be formed of calcium fluoride, lithium fluoride, or magnesium fluoride.

[0034] A linear first suction path 12c1 is formed inside the holding member 12 so as to cross the central axis of the disk when the holding member 12 is viewed from above. In addition, a linear second suction path 12c2 is formed so as to intersect at right angles with the first suction path 12c1 in a plane substantially parallel to the one surface 12a.

[0035] The first suction passage 12c1 and the second suction passage 12c2 are connected to each other at a point 12c3 located on the central axis of the disk. A plurality of openings 12d are formed on the outer periphery of the one surface 12a. Each opening 12d is formed from the one surface 12a to a predetermined depth not reaching the other surface 12b.

[0036] An opening 12d is formed at each end of the first suction passage 12c1 and each end of the second suction passage 12c2. The openings 12d are connected to each other by an outer circumferential suction passage 12e that is formed at a predetermined depth on the outer circumferential portion of the holding member 12.

[0037] A suction passage 12f extending in the radial direction is formed on the outer periphery of the opening 12d, and a suction source 14 such as an ejector is connected to the suction passage 12f (see FIG. 5). When the suction source 14 is operated to generate negative pressure, negative pressure is generated in the opening 12d. Therefore, the one surface 12a functions as a holding surface that sucks and holds the workpiece unit 21 (workpiece 11).

[0038] A part of the incident light is scattered or reflected in the flow paths such as the first suction path 12c1, the second suction path 12c2, the opening 12d, the outer peripheral suction path 12e, the suction path 12f, etc. Therefore, the flow paths of the holding member 12 are not completely transparent when viewed from the one surface 12a or the other surface 12b, and may be translucent or opaque.

[0039] However, a predetermined region of the holding member 12 excluding these flow paths is transparent from the one surface 12a to the other surface 12b. For example, a region divided into four by the first suction path 12c1 and the second suction path 12c2 and located radially inward of the outer circumferential suction path 12e of the holding member 12 is transparent from the one surface 12a to the other surface 12b.

[0040] A cylindrical frame 16 made of a metal material such as stainless steel is provided on the outer periphery of the holding member 12. An opening 16a is formed in the upper part of the frame 16 (see FIG. 5), and the holding member 12 is disposed so as to close this opening 16a.

[0041] 3 and 4, the frame 16 is supported by an X-axis moving table 18. The X-axis moving table 18 includes a rectangular bottom plate 18a. The lower end of a rectangular side plate 18b is connected to the front end (+Y direction) of the bottom plate 18a.

[0042] The front end of a top plate 18c, which has the same rectangular shape as the bottom plate 18a, is connected to the upper end of the side plate 18b. The bottom plate 18a, the side plate 18b, and the top plate 18c form a space 18d that is open on both the rear (-Y direction) side and the X-axis direction.

[0043] The lower part (-Z direction) of the bottom plate 18a is slidably attached to a pair of X-axis guide rails 20 fixed to the upper surface of a stationary base (not shown). In the vicinity of the X-axis guide rails 20, an X-axis linear scale 20a is provided.

[0044] A reading head (not shown) is provided on the underside of the X-axis moving table 18. The reading head is used to detect the scale of the X-axis linear scale 20a, thereby calculating the position (coordinate) of the X-axis moving table 18 in the X-axis direction and the amount of movement in the X-axis direction.

[0045] A nut portion (not shown) is provided on the lower surface side of the bottom plate 18a, and an X-axis ball screw 22 arranged approximately parallel to the X-axis direction is rotatably connected to this nut portion. An X-axis pulse motor 24 is connected to one end of the X-axis ball screw 22.

[0046] When the X-axis pulse motor 24 is operated, the X-axis ball screw 22 rotates, and the X-axis moving table 18 moves in the X-axis direction. The X-axis moving table 18, the pair of X-axis guide rails 20, the X-axis ball screw 22, the X-axis pulse motor 24, etc. constitute an X-axis moving mechanism 26.

[0047] On the upper surface side of the top plate 18c, the frame body 16 is supported rotatably about a rotation axis that is approximately parallel to the Z-axis direction. A side surface of the frame body 16 located above the top plate 18c functions as a pulley portion 16b.

[0048] A rotary drive source 30 such as a motor is provided on the outer side surface of the side plate 18b. A pulley 30a is provided on the rotary shaft of the rotary drive source 30. A belt 28 is wound around the pulley 30a and the pulley portion 16b.

[0049] When the rotary drive source 30 is operated, the frame 16 rotates around a rotation axis that is approximately parallel to the Z-axis direction. By controlling the rotation of the pulley 30a, the chuck table 10 rotates around the rotation axis by an arbitrary angle.

[0050] A Y-axis movement mechanism 32 that moves a lower imaging unit 54 (described later) in the Y-axis direction is provided on an extension line in the X-axis direction of the X-axis movement mechanism 26. The Y-axis movement mechanism 32 includes a pair of Y-axis guide rails 34 that are fixed to the upper surface of a stationary base (not shown) and are substantially parallel to the Y-axis direction.

[0051] A Y-axis moving table 36 is slidably mounted on the Y-axis guide rail 34. A nut portion (not shown) is provided on the underside of the Y-axis moving table 36, and a Y-axis ball screw 38 arranged substantially parallel to the Y-axis direction is rotatably connected to this nut portion.

[0052] A Y-axis pulse motor 40 is connected to one end of the Y-axis ball screw 38. When the Y-axis pulse motor 40 rotates the Y-axis ball screw 38, the Y-axis moving table 36 moves in the Y-axis direction.

[0053] A Y-axis linear scale (not shown) is provided near the Y-axis guide rail 34. Moreover, by detecting the graduations of the Y-axis linear scale with a reading head (not shown) provided on the underside of the Y-axis moving table 36, the position (coordinate) of the Y-axis moving table 36 in the Y-axis direction and the amount of movement in the Y-axis direction are calculated.

[0054] A Z-axis movement mechanism 42 is provided on the upper surface of the Y-axis movement table 36. The Z-axis movement mechanism 42 has a support structure 42a fixed to the upper surface of the Y-axis movement table 36. A pair of Z-axis guide rails 44 arranged approximately parallel to the Z-axis direction are fixed to one surface of the support structure 42a.

[0055] A Z-axis moving plate 46 is slidably attached to the Z-axis guide rail 44. A nut portion (not shown) is provided on the support structure 42a side of the Z-axis moving plate 46, and a Z-axis ball screw 48 arranged substantially parallel to the Z-axis direction is rotatably connected to this nut portion.

[0056] A Z-axis pulse motor 50 is connected to the upper end of the Z-axis ball screw 48. When the Z-axis ball screw 48 is rotated by the Z-axis pulse motor 50, the Z-axis moving plate 46 moves in the Z-axis direction.

[0057] A Z-axis linear scale (not shown) is provided near the Z-axis guide rail 44, and a reading head (not shown) is provided on the Z-axis moving plate 46. By detecting the graduations of the Z-axis linear scale with the reading head, the position (coordinates) of the Z-axis moving plate 46 in the Z-axis direction, etc. are calculated.

[0058] A lower imaging unit 54 is fixed to the Z-axis moving plate 46 via a support arm 52 whose longitudinal portion is disposed along the X-axis direction. Fig. 6 is an enlarged perspective view of the lower imaging unit 54. The lower imaging unit 54 is a so-called microscope camera unit that includes a low-magnification camera 56 and a high-magnification camera 58.

[0059] Each of the low-magnification camera 56 and the high-magnification camera 58 has a predetermined optical system such as a condenser lens, and an imaging element such as a charge-coupled device (CCD) image sensor or a complementary metal-oxide-semiconductor (CMOS) image sensor.

[0060] In this example, an imaging element capable of photoelectric conversion of visible light is used. The lower imaging unit 54 is disposed below the chuck table 10, and the optical axis of each condenser lens is disposed substantially perpendicular to the other surface 12b of the holding member 12.

[0061] An illumination device 56a for irradiating visible light onto the workpiece 11 and the like disposed above is provided on the side of the low-magnification camera 56. Similarly, an illumination device 58a is provided on the side of the high-magnification camera 58.

[0062] When imaging the workpiece 11 with the lower imaging unit 54, the X-axis moving table 18 is moved to place the lower imaging unit 54 in the space 18d. Then, by imaging the workpiece 11 from below via the holding member 12, an image of the front surface 11a side can be obtained.

[0063] Returning to Fig. 1, other components of the cutting device 2 will now be described. On both sides in the X-axis direction of the top plate 18c, a stretchable bellows-like cover is attached in a manner to cover the opening 4b. In addition, a gate-shaped support structure 4c is provided above the opening 4b so as to straddle the opening 4b in the Y-axis direction.

[0064] One side surface of the support structure 4c in the -X direction is provided with two processing unit movement mechanisms (indexing feed unit, cutting feed unit) 60. Each processing unit movement mechanism 60 shares a pair of Y-axis guide rails 62 fixed to one side surface of the support structure 4c.

[0065] The pair of Y-axis guide rails 62 are disposed substantially parallel to the Y-axis direction. Two Y-axis moving plates 64 are attached to the pair of Y-axis guide rails 62 in a manner that allows them to slide independently of each other.

[0066] A nut portion (not shown) is provided on one surface of the Y-axis moving plate 64, and a Y-axis ball screw 66 arranged approximately parallel to the Y-axis direction is rotatably connected to this nut portion. The nut portion of each Y-axis moving plate 64 is connected to a different Y-axis ball screw 66.

[0067] A Y-axis pulse motor 68 is connected to one end of each Y-axis ball screw 66. When the Y-axis ball screw 66 is rotated by the Y-axis pulse motor 68, the Y-axis moving plate 64 moves in the Y-axis direction.

[0068] One surface of Z-axis moving plate 70a is slidably attached to a pair of Z-axis guide rails 72 provided on the other surface of rear (-Y direction) Y-axis moving plate 64. Similarly, one surface of Z-axis moving plate 70b is slidably attached to a pair of Z-axis guide rails 72 provided on the other surface of front (+Y direction) Y-axis moving plate 64.

[0069] A nut portion (not shown) is provided on one surface of each of the Z-axis moving plates 70a and 70b, and a Z-axis ball screw 74 is rotatably connected to the nut portion. Each Z-axis ball screw 74 is disposed parallel to the Z-axis direction.

[0070] A Z-axis pulse motor 76 is connected to the upper end of the Z-axis ball screw 74. When the Z-axis pulse motor 76 rotates the Z-axis ball screw 74, the Z-axis moving plates 70a and 70b each move in the Z-axis direction.

[0071] A first cutting unit 78a is provided under the Z-axis moving plate 70a disposed on the rear (-Y direction) side. The first cutting unit 78a includes a cylindrical spindle housing 80a.

[0072] A cylindrical spindle 82a (see FIG. 8) is partially rotatably housed within the spindle housing 80a. A rotation drive mechanism (not shown), such as a motor, is provided at one end of the spindle 82a.

[0073] A first cutting blade 84a having an annular cutting edge is attached to the other end of the spindle 82a. The first cutting blade 84a in this example is a washer type (hubless type), but may be a hub type.

[0074] An upper imaging unit (first imaging unit) 86a is fixed to the lower part of the Z-axis moving plate 70a. Therefore, the position of the upper imaging unit 86a is fixed with respect to the first cutting unit 78a.

[0075] The upper imaging unit 86a is disposed above the chuck table 10. The upper imaging unit 86a is a so-called microscope camera unit, and has a predetermined optical system such as a condenser lens and an imaging element capable of photoelectrically converting visible light. The optical axis of the condenser lens of the upper imaging unit 86a is disposed substantially perpendicular to one surface 12a of the holding member 12.

[0076] Similarly, a second cutting unit 78b is provided on the lower part of the Z-axis moving plate 70b on the front (+Y direction) side. The second cutting unit 78b also includes a spindle housing 80b, and a part of a cylindrical spindle 82b (see FIG. 12) is rotatably accommodated in the spindle housing 80b.

[0077] A rotation drive mechanism (not shown) is provided at one end of the spindle 82b, and a second cutting blade 84b is attached to the other end of the spindle 82b. The second cutting blade 84b in this example is a washer type (hubless type), but may be a hub type.

[0078] However, the blade thickness (second thickness) 84b1 (see FIG. 12) of the second cutting blade 84b is thinner than the blade thickness (first thickness) 84a1 (see FIG. 8) of the first cutting blade 84a.

[0079] Therefore, the width 13b1 of the second machining groove (cutting groove) 13b formed when the workpiece 11 is cut by the second cutting blade 84b is smaller than the width 13a1 of the first machining groove (cutting groove) 13a formed by the first cutting blade 84a (see Figures 12 and 13).

[0080] An upper imaging unit (second imaging unit) 86b, whose position is fixed relative to the second cutting unit 78b, is provided below the Z-axis moving plate 70b. The structure of the upper imaging unit 86b is substantially the same as that of the upper imaging unit 86a.

[0081] 1 again, a circular opening 4d is provided behind the opening 4b (in the -Y direction). A cleaning unit 90 is provided in the opening 4d to clean the workpiece 11 and the like after cutting with cleaning water such as pure water.

[0082] A housing (not shown) is provided on the base 4, and a touch panel 92 serving as both an input unit and a display unit is provided on the front (+Y direction) side of the housing. Images captured by the upper imaging units 86a, 86b and the lower imaging unit 54 are displayed on the touch panel 92.

[0083] On the touch panel 92, a reference line 92a of the upper imaging unit 86a is displayed by image processing together with an image 88a captured by the upper imaging unit 86a (see FIGS. 10(A) and 10(B)). The reference line 92a is a straight line that crosses the center of the imaging area of ​​the upper imaging unit 86a and is approximately parallel to the X-axis direction.

[0084] The upper imaging unit 86a functions as an eye to check the area that will actually be cut by the first cutting unit 78a, and the reference line 92a corresponds to a line indicating the target position where the first center line 13a2 (see Figure 8) of the first cutting groove 13a will be formed.

[0085] Similarly, a reference line 92b is displayed on the touch panel 92 by image processing together with the image 88b captured by the lower imaging unit 54 (see FIGS. 14(A) and 14(B)). Similar to the reference line 92a, the reference line 92b is a straight line that crosses the center of the imaging area of ​​the lower imaging unit 54 and is approximately parallel to the X-axis direction.

[0086] Like the upper imaging unit 86a, the lower imaging unit 54 also functions as an eye for identifying the area that will actually be cut by the second cutting unit 78b, and the reference line 92b corresponds to a line indicating the target position where the second center line 13b2 (see Figure 12) of the second cutting groove 13b will be formed.

[0087] The origin positions of the upper imaging unit 86a and the lower imaging unit 54 are preset to coincide with each other. Therefore, the Y coordinates of the reference lines 92a and 92b are also preset to coincide with each other and will not shift from each other.

[0088] In addition to images captured by the lower imaging unit 54 and the upper imaging units 86a, 86b, processing conditions, a GUI (Graphical User Interface), etc. are displayed on the touch panel 92. The cutting device 2 includes a control unit 94 that controls the touch panel 92 and the like.

[0089] The control unit 94 also controls the suction source 14, the X-axis moving mechanism 26, the rotational drive source 30, the Y-axis moving mechanism 32, the Z-axis moving mechanism 42, the lower imaging unit 54, the processing unit moving mechanism 60, the first cutting unit 78a, the second cutting unit 78b, the upper imaging units 86a, 86b, etc.

[0090] The control unit 94 is configured by a computer including a processing device such as a processor represented by a CPU (Central Processing Unit), and a storage device 96. The storage device 96 has a main storage device such as a DRAM (Dynamic Random Access Memory), an SRAM (Static Random Access Memory), or a ROM (Read Only Memory), and an auxiliary storage device such as a flash memory, a hard disk drive, or a solid state drive.

[0091] The auxiliary storage device stores software including a predetermined program. The function of the control unit 94 is realized by operating the processing device according to this software. Next, a cutting method (machining method) for cutting the workpiece 11 by step cutting using the cutting device 2 will be described.

[0092] 7 is a flow diagram of the cutting method according to the first embodiment. In order to cut the workpiece 11, first, with the back surface 11b side exposed upward, the front surface 11a side is suction-held on the chuck table 10 via the tape 17 (holding step S10).

[0093] After the holding step S10, if cutting of all of the planned division lines 13 along the first direction has not been completed (NO in S20), the first cutting blade 84a and the second cutting blade 84b are used in sequence to sequentially form grooves (first groove 13a, second groove 13b) in the workpiece 11 (groove forming step).

[0094] The groove forming process of this embodiment includes steps S30 to S39, which will be described later. In the groove forming process, first, the lower imaging unit 54 captures an image of the front surface 11a side and performs alignment. Next, the rotary drive source 30 is operated to make the division line 13 approximately parallel to the X-axis direction (so-called θ alignment is performed).

[0095] Thereafter, a first groove forming step S30 is performed. Fig. 8 is a diagram showing the first groove forming step S30. In the first groove forming step S30, a first cutting position is specified to place the first cutting blade 84a on an extension line of one of the planned division lines 13, and the lower end of the first cutting blade 84a rotating at high speed is positioned at a predetermined depth 23 between the front surface 11a and the back surface 11b.

[0096] In this state, the X-axis moving table 18 is fed for processing to form one first processed groove 13a (so-called half-cut groove) having a predetermined depth 23 that does not reach the surface 11a. Note that the depth 23 is not limited to half the depth of the thickness of the workpiece 11, and can be adjusted to various depths depending on the workpiece 11.

[0097] After forming one first groove 13a, the upper imaging unit 86a is used to capture an image of the first groove 13a exposed on the back surface 11b with visible light (first imaging step S31). Fig. 9 is a diagram showing the first imaging step S31.

[0098] After the first imaging step S31, the control unit 94 detects the deviation of the first center line 13a2 of the first processed groove 13a from the reference line 92a (first kerf check step S32).

[0099] The first center line 13a2 is located at the center in the width direction of the first machined groove 13a and is approximately parallel to the X-axis direction. The first center line 13a2 approximately corresponds to the center 84a2 (see FIG. 8) in the thickness direction of the cutting edge of the first cutting blade 84a during cutting.

[0100] Fig. 10(A) is an example of an image including the first groove 13a. In Fig. 10(A), the position of the first center line 13a2 and the position of the reference line 92a coincide with each other in the Y-axis direction. In this case (i.e., YES in S32), the process proceeds to the additional first groove forming step S34.

[0101] Incidentally, before cutting the workpiece 11, an operation of aligning the first center line 13a2 and the reference line 92a (i.e., hairline alignment) is performed using a mirror wafer or the like. Therefore, the first center line 13a2 and the reference line 92a usually coincide with each other.

[0102] However, when the workpiece 11 is made of a hard material, when the workpiece 11 is relatively thick, when the cutting direction is oblique to the tangent direction of a point on the outer peripheral edge of the workpiece 11, etc., the first center line 13a2 may deviate from the reference line 92a.

[0103] Fig. 10B is another example of an image including the first processed groove 13a. In Fig. 10B, the deviation amount and deviation direction of the first center line 13a2 from the reference line 92a in the Y-axis direction are indicated by vector B1.

[0104] In the first kerf check process S32, if the amount of deviation is greater than a predetermined threshold (for example, 5 μm), the control unit 94 prompts the worker to align the hairlines by sounding from a speaker (not shown) or by displaying an alarm on the touch panel 92.

[0105] While looking at the image 88a, the worker operates the touch panel 92 to move the processing unit moving mechanism 60 and move the upper imaging unit 86a in the Y-axis direction, thereby aligning the reference line 92a with the first center line 13a2 (first hairline alignment process S33).

[0106] In addition, for example, in order to realize high-precision cutting processing, regardless of whether an alarm is issued in the first kerf check process S32, an operator may check the image 88a and perform the first hairline alignment process S33 as necessary.

[0107] Based on the movement direction and movement distance of the upper imaging unit 86a in the first hairline alignment process S33, the control unit 94 detects the amount and direction of deviation of the upper imaging unit 86a (vector B1 shown in Figure 10 (B)) and stores this in the memory device 96.

[0108] During cutting with the first cutting blade 84a after the first hairline alignment step S33, the control unit 94 corrects the position of the center 84a2 of the first cutting blade 84a so as to cancel out the amount and direction of this deviation.

[0109] In the subsequent additional first groove forming step S34, the first cutting unit 78a is indexed and fed by a predetermined street pitch, whereby the first cutting blade 84a is positioned on the adjacent intended division line 13, and the first groove 13a is formed in the same manner.

[0110] In the additional first groove forming step S34, a plurality of grooves (specifically, four first grooves 13a) are formed. Fig. 11 is a diagram showing the additional first groove forming step S34. In this manner, a total of five first grooves 13a are formed from S30 to S34.

[0111] After the additional first machining groove forming process S34, a second cutting position corresponding to the first cutting position is specified, so that the second cutting blade 84b is positioned on the extension line of the first machining groove 13a formed in the first machining groove forming process S30, and the lower end of the second cutting blade 84b rotating at high speed is positioned between the surface 11a and the first face 12a.

[0112] Then, the X-axis moving table 18 is fed for machining. This forms a second groove 13b that reaches the surface 11a (second groove forming step S35). Figure 12 is a diagram showing the second groove forming step S35. In the second groove forming step S35, the workpiece 11 is divided at the boundary between one first groove 13a and one second groove 13b.

[0113] After the second machining groove forming process S35, the lower imaging unit 54 (e.g., a high-magnification camera 58 and a lighting device 58a) is used to image the second machining groove 13b formed in the surface 11a with visible light through the chuck table 10 (second imaging process S36).

[0114] 13 is a diagram showing the second imaging step S36. In this embodiment, the second machining groove 13b is imaged by the lower imaging unit 54, not the upper imaging units 86a and 86b, so that the second machining groove 13b can be imaged without any problems.

[0115] After the second imaging step S36, the control unit 94 detects the deviation of the second center line 13b2 of the second processed groove 13b from the reference line 92b (second kerf check step S37).

[0116] The second center line 13b2 is located at the center of the width of the second cutting groove 13b and is approximately parallel to the X-axis direction, and approximately corresponds to the center 84b2 (see Figure 12) in the thickness direction of the cutting edge of the second cutting blade 84b during cutting.

[0117] Fig. 14(A) is an example of an image including the second groove 13b. In Fig. 14(A), the position of the second center line 13b2 and the position of the reference line 92b coincide with each other in the Y-axis direction. In this case (i.e., YES in S37), the process proceeds to the additional second groove forming step S39.

[0118] Normally, the second center line 13b2 and the reference line 92b coincide with each other. However, as described above, when the workpiece 11 is made of a hard material, the second center line 13b2 may deviate from the reference line 92b.

[0119] Fig. 14B is another example of an image including the second processed groove 13b. In Fig. 14B, the deviation amount and deviation direction of the second center line 13b2 from the reference line 92b in the Y-axis direction are indicated by vector B2.

[0120] In the second kerf check step S37, if the amount of deviation is greater than a predetermined threshold (for example, 5 μm), the control unit 94 issues an alarm to prompt the worker to align the hairline.

[0121] While looking at image 88b, the worker operates touch panel 92 to move Y-axis moving mechanism 32 and move lower imaging unit 54 in the Y-axis direction, thereby aligning reference line 92b with second center line 13b2 (second hairline alignment process S38).

[0122] In addition, for example, in order to realize high-precision cutting processing, regardless of whether an alarm is issued in the second kerf check process S37, the worker may check the image 88b and perform the second hairline alignment process S38 as necessary.

[0123] Based on the movement direction and movement distance of the lower imaging unit 54 in the second hairline alignment process S38, the control unit 94 detects the amount and direction of deviation of the lower imaging unit 54 (vector B2 shown in Figure 14 (B)) and stores this in the memory device 96.

[0124] During cutting with the second cutting blade 84b after the second hairline alignment step S38, the control unit 94 corrects the position of the center 84b2 of the second cutting blade 84b so as to cancel out the amount and direction of deviation.

[0125] In this embodiment, the first kerf check process S32 and the second kerf check process S37 are collectively referred to as a detection process. In the detection process, it is possible to detect whether the position of the first center line 13a2 obtained in the first imaging process S31 and the position of the second center line 13b2 obtained in the second imaging process S36 match within the XY plane (a predetermined plane).

[0126] When at least one of the first hairline alignment step S33 and the second hairline alignment step S38 has been performed, it is determined in the detection step that the first center line 13a2 and the second center line 13b2 do not coincide with each other.

[0127] In this embodiment, the first hairline alignment step S33 and the second hairline alignment step S38, which are performed as necessary, are collectively referred to as a correction step. Through the correction step, the center 84a2 of the blade thickness 84a1 of the first cutting blade 84a and the center 84b2 of the blade thickness 84b1 of the second cutting blade 84b coincide with each other.

[0128] After S37, or after S37 and S38, the remaining four first grooves 13a are similarly formed with second grooves 13b, respectively (additional second groove forming step S39). Fig. 15 is a cross-sectional view of the workpiece 11 after the additional second groove forming step S39.

[0129] Next, the process returns to S20, and if the result is NO in S20, the first groove forming step S30 to the additional second groove forming step S39 are performed again. After all the division lines 13 along the first direction are cut in this manner, the chuck table 10 is rotated 90 degrees.

[0130] Then, cutting is performed similarly on all the division lines 13 along the second direction perpendicular to the first direction. After all the division lines 13 along the first direction and the second direction have been cut (YES in S20), cutting is terminated.

[0131] In the first embodiment, if the position of the first center line 13a2 and the position of the second center line 13b2 do not coincide in the XY plane, in a correction process (S33, S38), at least one of the position of the center 84a2 of the first cutting blade 84a and the position of the center 84b2 of the second cutting blade 84b is corrected so that the position of the first center line 13a2 and the position of the second center line 13b2 coincide.

[0132] Therefore, in the cutting after the correction process, the first center line 13a2 of the first machined groove 13a on the back surface 11b side and the second center line 13b2 of the second machined groove 13b on the front surface 11a side can be made to coincide with each other. This cutting method is particularly effective when the workpiece 11 is step-cut.

[0133] (First Modification) In the first groove forming step S30, only one first groove 13a may be formed instead of multiple grooves. Also, the first groove 13a may be formed in a peripheral surplus area existing around the device area, not in the device area where the device 15 is formed.

[0134] (Second Modification) In the first embodiment, the blade thickness 84b1 of the second cutting blade 84b is smaller than the blade thickness 84a1 of the first cutting blade 84a, but the blade thickness 84b1 and the blade thickness 84a1 may be the same thickness.

[0135] Second Embodiment Next, a second embodiment will be described. However, the cutting device 2 of the second embodiment includes a lower imaging unit (third imaging unit) 100 capable of imaging the workpiece 11 with infrared rays, instead of the lower imaging unit 54.

[0136] The lower imaging unit 100 is also a so-called microscope camera unit that includes a low-magnification camera and a high-magnification camera. However, each camera has an imaging element capable of photoelectrically converting infrared light, and an illumination device attached to each camera can irradiate infrared light (e.g., near-infrared light).

[0137] In the second embodiment, the workpiece 11 is also cut according to the flow of Fig. 7. However, in the second embodiment, both the first imaging step S31 and the second imaging step S36 are performed using the lower imaging unit 100. This is different from the first embodiment.

[0138] 16A is a diagram showing a first imaging step S31 according to the second embodiment. In the first imaging step S31, the focus of a high-magnification camera is adjusted to the back surface 11b via the chuck table 10, and an image of the first processing groove 13a formed on the back surface 11b is captured with infrared light.

[0139] 16B is a diagram showing a second imaging step S36 according to the second embodiment. In the second imaging step S36, the focus of the high-magnification camera is adjusted to the surface 11a via the chuck table 10, and an image of the second processing groove 13b formed in the surface 11a is captured with infrared light.

[0140] In the second embodiment, as in the first embodiment, even if the first center line 13a2 and the second center line 13b2 are misaligned, the first center line 13a2 in the first machining groove 13a on the back surface 11b side and the second center line 13b2 in the second machining groove 13b on the front surface 11a side can be made to coincide with each other in the cutting after the correction process.

[0141] In addition, the structures, methods, and the like according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. A modified example of the first embodiment may be applied to the second embodiment. [Explanation of symbols]

[0142] 2: Cutting device, 4: Base, 4a, 4b: Opening, 4c: Support structure, 4d: Opening 6: Cassette, 10: Chuck table 11: Workpiece, 11a: Front surface, 11b: Back surface 12: holding member, 12a: one surface, 12b: other surface 12c1: 1st suction path, 12c2: 2nd suction path, 12c3: Point, 12d: Opening 12e: Peripheral suction path, 12f: Suction path 13: Planned division line 13a: first processing groove, 13a1: width, 13a2: first center line 13b: second machining groove, 13b1: width, 13b2: second center line 14: suction source, 16: frame, 16a: opening, 16b: pulley 15: device, 17: tape, 19: frame, 21: workpiece unit, 23: depth 18: X-axis moving table, 18a: bottom plate, 18b: side plate, 18c: top plate, 18d: space 20: X-axis guide rail, 20a: X-axis linear scale, 22: X-axis ball screw 24: X-axis pulse motor, 26: X-axis movement mechanism 28: belt, 30: rotary drive source, 30a: pulley 32: Y-axis movement mechanism, 34: Y-axis guide rail, 36: Y-axis movement table 38: Y-axis ball screw, 40: Y-axis pulse motor 42: Z-axis movement mechanism, 42a: support structure, 44: Z-axis guide rail 46: Z-axis moving plate, 48: Z-axis ball screw, 50: Z-axis pulse motor 52: Support arm, 54,100: Lower imaging unit 56: low magnification camera, 56a: lighting device 58: High-magnification camera, 58a: Lighting device 60: Processing unit moving mechanism, 62: Y-axis guide rail, 64: Y-axis moving plate 66: Y-axis ball screw, 68: Y-axis pulse motor 70a, 70b: Z-axis moving plate 72: Z-axis guide rail, 74: Z-axis ball screw, 76: Z-axis pulse motor 78a: first cutting unit, 78b: second cutting unit 80a, 80b: Spindle housing 82a, 82b: Spindle 84a: first cutting blade, 84a1: blade thickness, 84a2: center 84b: second cutting blade, 84b1: blade thickness, 84b2: center 86a: upper imaging unit, 86b: upper imaging unit, 88a, 88b: images 90: cleaning unit, 92: touch panel, 92a, 92b: reference lines 94: control unit, 96: storage device, A: area, B1, B2: vector

Claims

1. A method for processing a workpiece, comprising the steps of: a holding step of holding a front side of the workpiece with a holding table having an area formed of a transparent material while exposing a back side of the workpiece; a groove forming step of cutting the workpiece held by the holding table with a cutting blade to form a groove in the workpiece, The processing groove forming step is a first groove forming step of forming a first groove having a predetermined depth not reaching the surface with a first cutting blade having a first thickness; a second groove forming step of dividing the workpiece by positioning a second cutting blade having a second thickness in the first groove and forming a second groove along the first groove and reaching the surface; a first imaging step of imaging the first processed groove on the back side of the workpiece with visible light using a first imaging unit arranged above the workpiece; a second imaging step of imaging the second processed groove on the front surface side of the workpiece with visible light through the holding table by using a second imaging unit arranged below the workpiece; a detection step of detecting whether or not a position of a first center line of the first processed groove imaged in the first imaging step and a position of a second center line of the second processed groove imaged in the second imaging step coincide with each other within a predetermined plane; having A method for processing a workpiece, characterized in that, if, in the detection process, the position of the first center line and the position of the second center line do not coincide within the specified plane, the processing groove forming process further includes a correction process for correcting the position of the center of the cutting blade so that the position of the first center line and the position of the second center line coincide.

2. A method for processing a workpiece, comprising: a holding step of holding a front side of the workpiece with a holding table having an area formed of a transparent material while exposing a back side of the workpiece; a groove forming step of cutting the workpiece held by the holding table with a cutting blade to form a groove in the workpiece, The processing groove forming step is a first groove forming step of forming a first groove having a predetermined depth not reaching the surface with a first cutting blade having a first thickness; a second groove forming step of dividing the workpiece by positioning a second cutting blade having a second thickness in the first groove and forming a second groove along the first groove and reaching the surface; a first imaging step of imaging the first machining groove on the back side of the workpiece with infrared light through the holding table by using a third imaging unit arranged below the workpiece; a second imaging step of imaging the second processed groove on the front surface side of the workpiece with infrared light through the holding table by using the third imaging unit; a detection step of detecting whether or not a position of a first center line of the first processed groove imaged in the first imaging step and a position of a second center line of the second processed groove imaged in the second imaging step coincide with each other within a predetermined plane; having A method for processing a workpiece, characterized in that, if, in the detection process, the position of the first center line and the position of the second center line do not coincide within the specified plane, the processing groove forming process further includes a correction process for correcting the position of the center of the cutting blade so that the position of the first center line and the position of the second center line coincide.

3. 3. The method for machining a workpiece according to claim 1, wherein the second cutting blade has a thickness thinner than that of the first cutting blade.

Images