Cutting apparatus and cutting method

Abstract

To stably form a step part with a sufficient width at an outer peripheral end of a wafer.SOLUTION: According to an aspect of the present invention, there is provided a cutting apparatus for cutting an outer circumferential end of a wafer, the cutting apparatus including a chuck table rotatable about a first axis of rotation, a spindle extending along a second axis of rotation that does not intersect the first axis of rotation, a measuring unit for measuring a width of a stepped portion of the wafer, a first moving mechanism for moving the cutting unit and the chuck table relative to each other in a first direction, a second moving mechanism for moving the cutting unit and the chuck table relative to each other in a second direction, and a controller. The controller includes a target storage section that stores a target value of the width of the step portion, a calculation section that calculates a correction value on the basis of a measured value of the width of the step portion and the target value, and an adjustment section that operates the first movement mechanism and the second movement mechanism on the basis of the calculated correction value to adjust the relative position between the cutting unit and the chuck table.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a cutting device and a cutting method for forming a step portion (trim portion) on the outer peripheral edge of a wafer that includes a chamfered portion on the outer peripheral edge. [Background technology]

[0002] A disk-shaped wafer made of a semiconductor material such as silicon usually has a chamfered portion (also called a beveled portion) formed at its outer periphery. The chamfered portion has its corners rounded off. Therefore, when the wafer is thinned by grinding it from the backside, a so-called knife edge (also called a sharp edge) is formed at the outer periphery.

[0003] If a knife edge is formed on the outer peripheral edge, the outer peripheral edge is likely to crack, chip, etc. during transportation of the wafer after grinding. Therefore, a processing method called edge trimming has been proposed in which a cutting device is used to remove at least a portion of the chamfer on the front surface side of the wafer before grinding the wafer (see, for example, Patent Document 1).

[0004] When edge trimming is performed, a cutting device equipped with a cutting unit and a chuck table is used. The cutting unit has a spindle and an annular cutting blade attached to the tip of the spindle. The cutting blade has an annular cutting edge portion. The cutting edge portion has an annular first side surface, an annular second side surface opposite the first side surface, and a third side surface between the first side surface and the second side surface. The cutting blade is attached to the spindle so as to be rotatable around the centerline of the cutting edge portion passing through the center of the first side surface and the center of the second side surface. The upper surface of the chuck table serves as a holding surface for holding a wafer, and the chuck table can rotate around a rotation center passing through the center of the holding surface.

[0005] Typically, the edge trimming procedure begins by first suction-holding the wafer on the chuck table. At this time, the wafer is suction-held on the chuck table so that the rotation center of the chuck table and the radial center of the wafer are approximately aligned. Then, the spindle of the cutting unit is rotated, and the cutting blade begins to rotate around the centerline of the cutting edge.

[0006] Then, with the cutting blade and chuck table positioned so that the first side of the cutting edge of the cutting blade is positioned closer to the wafer than the second side, and the center line of the cutting edge (second rotation axis) is perpendicular to the rotation center of the chuck table (first rotation axis), the cutting blade is caused to cut into the peripheral portion of the surface of the wafer.

[0007] After the cutting blade cuts into the peripheral edge of the wafer surface, the chuck table is slowly rotated while the spatial position of the cutting blade, which is rotating at high speed, is kept substantially fixed. Therefore, during cutting, the wafer comes into contact with not only the third side surface of the cutting blade but also the first side surface. This has led to problems such as chipping occurring easily in the area of ​​the wafer that comes into contact with the side surface of the cutting blade.

[0008] Therefore, an edge trimming method known as angle trimming is implemented (see Patent Document 2). In angle trimming, the cutting blade is positioned so that the center of rotation of the cutting blade (second rotation axis) does not intersect with the center of rotation of the chuck table (first rotation axis). With angle trimming, the side of the cutting edge of the cutting blade is less likely to come into contact with the wafer, making it less likely that problems such as wafer chipping caused by contact with the side of the cutting edge will occur. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-173961 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-3216 Summary of the Invention [Problem to be solved by the invention]

[0010] Unlike edge trimming without angle trimming, the width of the step (trimmed portion) formed on the outer edge of a wafer by angle trimming depends not only on the width of the outer peripheral surface (third side surface) of the cutting blade but also on the diameter of the cutting blade's cutting edge. Furthermore, when angle trimming is performed on multiple wafers sequentially, the cutting blade's cutting edge wears out and its diameter gradually decreases. Therefore, with angle trimming, the width of the step formed on the wafer gradually decreases as the cutting edge wears out, making it impossible to consistently form step portions of the intended width on multiple wafers. If a sufficiently wide step is not formed on the wafer, the chamfer cannot be sufficiently removed from the wafer.

[0011] The present invention has been made in consideration of the above problems, and has as its object to provide a cutting device and cutting method that can stably form a step portion of sufficient width at the outer peripheral edge of a wafer in edge trimming performed by angle trimming. [Means for solving the problem]

[0012] According to one aspect of the present invention, a cutting device for cutting a peripheral edge of a wafer having a chamfered portion at the peripheral edge to form a step portion includes a chuck table capable of holding a wafer placed on a holding surface and rotatable about a first rotation axis that intersects with the holding surface, a cutting unit having a spindle aligned along a second rotation axis that does not intersect with the first rotation axis, a cutting blade attached to the tip of the spindle, and capable of rotating the spindle with the cutting blade attached to the tip about the second rotation axis, a measuring unit that is held on the chuck table and measures the width of the step portion of the wafer that has been cut by the cutting unit to form the step portion, and a measuring unit that moves the cutting unit and the chuck table relatively in a first direction parallel to the second rotation axis. a first moving mechanism that moves the cutting unit and the chuck table relative to each other in a second direction that is parallel to the holding surface and perpendicular to the first direction, a second moving mechanism that moves the cutting unit and the chuck table relatively in a second direction that is parallel to the holding surface and perpendicular to the first direction, and a controller, wherein the controller includes: a target memory unit that stores a target value for the width of the step portion to be formed on the wafer by the cutting unit; a calculation unit that calculates correction values ​​for the first moving mechanism and the second moving mechanism based on the target value and a measurement value obtained by measuring the width of the step portion of the wafer with the measurement unit; and an adjustment unit that operates the first moving mechanism and the second moving mechanism based on the correction value calculated by the calculation unit to adjust the relative position of the cutting unit and the chuck table.

[0013] Preferably, the calculation unit of the controller can calculate, in a plane parallel to the holding surface of the chuck table, the angle formed by a first line connecting a reference point on the second rotation axis that represents the position of the cutting edge portion of the cutting blade and the first rotation axis, as the cutting angle, calculate an angle correction value for correcting the cutting angle based on the cutting angle, the measurement value, and the target value, and calculate the correction values ​​for each of the first moving mechanism and the second moving mechanism based on the angle correction value.

[0014] According to another aspect of the present invention, there is provided a cutting method for cutting a peripheral edge of a wafer having a chamfered portion at the peripheral edge to form a step portion at the peripheral edge, the method comprising: a first cutting step in which the wafer is placed on a holding surface of a chuck table rotatable about a first rotation axis that penetrates a central region of the holding surface, the wafer is held by the chuck table, a cutting unit has a spindle aligned along a second rotation axis that does not intersect with the first rotation axis, and the cutting blade is attached to the tip of the spindle, and the cutting blade is rotated about the second rotation axis to cut into the chamfered portion of the wafer, and the chuck table is rotated about the first rotation axis, thereby cutting the peripheral edge of the wafer to form a first step portion; a measuring step in which, simultaneously with or after the first cutting step, the width of the first step portion formed on the wafer is measured to obtain a measurement value; and the measurement value obtained in the measuring step. and a target width; and a second cutting step, after the correction step, of cutting the first stepped portion of the outer peripheral edge of the wafer by rotating the cutting blade about the second rotation axis while causing the cutting blade to cut into the chamfered portion of the wafer and rotating the chuck table about the first rotation axis, thereby cutting the first stepped portion of the outer peripheral edge of the wafer to form a second stepped portion, wherein in the correction step, both a first correction value for correcting a first movement mechanism that moves the spindle and the chuck table relatively in a direction parallel to the second rotation axis and a second correction value for correcting a second movement mechanism that moves the spindle and the chuck table relatively in a direction parallel to the holding surface and perpendicular to the second rotation axis are calculated based on the measurement value and the target value, and the first movement mechanism is corrected with the first correction value and the second movement mechanism is corrected with the second correction value.

[0015] Alternatively, according to another aspect of the present invention, there is provided a cutting method for cutting the outer peripheral edges of a first wafer and a second wafer, each having a chamfered portion at the outer peripheral edge, to form a step portion at each of the outer peripheral edges, the method comprising: a first cutting step in which the first wafer is placed on a holding surface of a chuck table rotatable about a first rotation axis that penetrates a central region of the holding surface, the first wafer is held by the chuck table, a cutting unit has a spindle aligned with a second rotation axis that does not intersect with the first rotation axis, and the cutting blade is attached to the tip of the spindle, and the cutting blade is rotated about the second rotation axis to cut into the chamfered portion of the first wafer, and the chuck table is rotated about the first rotation axis, thereby cutting the outer peripheral edges of the first wafer to form a first step portion; a measuring step, simultaneous with or after the first cutting step, of measuring the width of the first step portion formed in the first wafer to obtain a measurement value; and a measuring step in which the width of the first step portion formed in the first wafer is measured based on the measurement value obtained in the measuring step and a target width. a correcting step of correcting the relative positions of the chuck table and the cutting blade based on the corrected position; and a second cutting step of, after the correcting step, placing the second wafer on the holding surface of the chuck table and holding the second wafer with the chuck table, rotating the cutting blade around the second rotation axis to cut into the chamfered portion of the second wafer, and rotating the chuck table around the first rotation axis to cut the outer circumferential edge of the second wafer and form a second step portion, In the correction step, a first correction value for correcting a first moving mechanism that moves the spindle and the chuck table relatively in a direction parallel to the second rotation axis, and a second correction value for correcting a second moving mechanism that moves the spindle and the chuck table relatively in a direction parallel to the holding surface and perpendicular to the second rotation axis are both calculated based on the measured value and the target value, and the first moving mechanism is corrected with the first correction value and the second moving mechanism is corrected with the second correction value.

[0016] Preferably, in the correction step, in a plane parallel to the holding surface of the chuck table, the angle formed by a first line connecting a reference point on the second rotation axis that represents the position of the cutting edge portion of the cutting blade and the first rotation axis, and the second rotation axis, is calculated as the cutting angle; an angle correction value for correcting the cutting angle is calculated based on the cutting angle, the measurement value, and the target value; and the first correction value and the second correction value are calculated based on the angle correction value. [Effects of the Invention]

[0017] A cutting device (cutting method) according to one aspect of the present invention uses a first movement mechanism that moves the cutting unit and the chuck table relatively in a first direction, and a second movement mechanism that moves them in a second direction perpendicular to the first direction. The width of a step portion formed on a wafer by the cutting unit is measured by a measurement unit, and correction values ​​for the first movement mechanism and the second movement mechanism are calculated based on the obtained measurement value and a target cutting width. The first movement mechanism and the second movement mechanism are then operated based on the calculated correction values ​​to adjust the relative positions of the cutting unit and the chuck table.

[0018] In this case, when the width of the step formed on the wafer becomes smaller due to wear of the cutting blade in the angle trim, the measured value of the width of the step measured by the measurement unit becomes smaller, and a correction value is calculated to adjust the relative positions of the cutting unit and the chuck table, so that the step can be stably formed on the wafer with the expected width.

[0019] Therefore, the present invention provides a cutting device and cutting method that can stably form a step portion with a sufficient width at the outer peripheral edge of a wafer in edge trimming performed by angle trimming. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1(A) is a perspective view showing a schematic diagram of a wafer, and FIG. 1(B) is a cross-sectional view taken along line AA in FIG. 1(A). [Figure 2] FIG. 2 is a perspective view schematically showing a cutting device. [Figure 3] FIG. 2 is a plan view schematically showing a chuck table that holds a wafer and a cutting unit. [Figure 4] Figure 4(A) is a plan view of the first cutting step, Figure 4(B) is a cross-sectional view of the first cutting step as viewed in the direction of arrow A1 in Figure 4(A), and Figure 4(C) is a side view of the first cutting step as viewed in the direction of arrow A2 in Figure 4(A). [Figure 5] Figure 5(A) is a side view that shows a schematic diagram of the cutting edge of the cutting blade before it is worn down, cutting the outer peripheral edge of the wafer to form a step portion (trim portion), and Figure 5(B) is a side view that shows a schematic diagram of the cutting edge of the cutting blade that has worn down to a certain extent, cutting the outer peripheral edge of the wafer to form a step portion (trim portion). [Figure 6] FIG. 6(A) is a plan view showing a schematic diagram of a cutting edge portion before it is worn out, cutting a wafer to form a step portion, and FIG. 6(B) is a plan view showing a schematic diagram of a cutting edge portion after it is worn out, cutting a wafer to form a step portion. [Figure 7] FIG. 7(A) is a cross-sectional view that schematically shows how the vicinity of a step portion of a wafer is imaged with a camera unit, and FIG. 7(B) is a cross-sectional view that schematically shows how the width of the step portion is determined with a laser displacement meter. [Figure 8] FIG. 8 is a plan view schematically showing how the relative positions of the cutting unit and the chuck table are adjusted by operating the first moving mechanism and the second moving mechanism based on the correction value. [Figure 9] 3 is a flowchart showing the flow of each step of the cutting method according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. First, a wafer to be cut by a cutting device and a cutting method according to this embodiment will be described. Fig. 1(A) is a perspective view of a wafer 11, and Fig. 1(B) is a cross-sectional view taken along line AA in Fig. 1(A).

[0022] The wafer 11 is a disk-shaped wafer made of a semiconductor material such as silicon. It has a circular first surface (first face, front face) 11a and a circular second surface (second face, back face) 11b opposite to the first surface 11a. However, the material and shape of the wafer 11 are not limited to these.

[0023] A notch 11c is formed in a portion of the peripheral edge (outer peripheral end) of the wafer 11 to indicate the crystal orientation of the wafer 11. Note that the wafer 11 may have an orientation flat formed thereon instead of the notch 11c. Furthermore, the wafer 11 may not have the notch 11c or the orientation flat formed thereon. The wafer 11 may be a so-called bonded wafer in which two wafers having approximately the same diameter are bonded together with an adhesive or the like.

[0024] As shown in FIG. 1(A), planned dividing lines 13 are set in a grid pattern on the first surface 11a. The first surface 11a is divided into a plurality of regions by the planned dividing lines 13, and devices 15 such as ICs (Integrated Circuits) are formed in each of the plurality of regions. When the wafer 11 is ground from the second surface 11b side to be thinned, and then divided along the planned dividing lines 13, individual thin device chips are obtained. However, the planned dividing lines 13 do not necessarily have to be set on the wafer 11. Furthermore, the devices 15 do not necessarily have to be formed on the wafer 11.

[0025] 1(B), the peripheral edge of the wafer 11 is formed with a rounded chamfered portion 11d by removing the corners of the peripheral edge in order to increase the mechanical strength of the wafer 11. When the wafer 11 with the chamfered portion 11d formed thereon is ground from the second surface 11b side to thin it, the remaining portion of the chamfered portion 11d becomes a knife edge.

[0026] If a knife edge is formed on the outer peripheral edge, the outer peripheral edge is likely to crack, chip, etc. during transportation of the wafer after grinding. Therefore, before grinding the wafer 11, a processing method called edge trimming is performed in which at least a part of the chamfered portion 11d on the first surface 11a side of the wafer 11 is removed using a cutting device.

[0027] The cutting device according to this embodiment is used for edge trimming processing of a wafer 11. The cutting device will be described below. The cutting device processes a wafer 11 as a workpiece. FIG. 2 is a perspective view showing a schematic view of the cutting device 2. The X1 axis direction (second direction, horizontal direction), Y1 axis direction (first direction, horizontal direction), and Z1 axis direction (vertical direction, up-down direction) shown in FIG. 2 are perpendicular to each other.

[0028] The cutting device 2 has a base 4 that supports or houses each of the components. A plurality of exterior panels 6 that cover the base 4 are provided above the base 4. A space is formed inside the box defined by the plurality of exterior panels 6.

[0029] This space is provided with a chuck table (holding table) 20 that suction-holds the wafer 11. Fig. 4(B) is a cross-sectional view that schematically shows the chuck table 20. The chuck table 20 has a disk-shaped frame 22 made of metal.

[0030] A disk-shaped recess 22b is formed on the upper surface of the frame 22. A disk-shaped porous plate 24 having approximately the same diameter as the recess 22b is fixed to the recess 22b. The porous plate 24 is made of, for example, porous ceramics.

[0031] A suction path 22c is formed inside the frame 22, one end of which is exposed to the recess 22b and the other end of which is exposed to the outer surface of the frame 22. A suction source (not shown), such as a vacuum pump, is connected to the other end of the suction path 22c via piping and a valve.

[0032] The negative pressure generated by the suction source can be transmitted to the upper surface 24a of the porous plate 24 via the suction path 22c and the holes in the porous plate 24. The upper surface 22a of the frame 22 and the upper surface 24a of the porous plate 24 are substantially flush with each other, and form a substantially flat holding surface (upper surface) 20a along the X1Y1 plane.

[0033] A rotation drive mechanism (not shown), such as a motor, is connected to the bottom of the chuck table 20. By operating this rotation drive mechanism, the chuck table 20 rotates around a first rotation axis (table rotation axis) 24c that passes through the center (central region) of the holding surface 20a of the chuck table 20. The first rotation axis 24c is disposed approximately parallel to the Z1 axis. In other words, the first rotation axis 24c is disposed so as to be perpendicular to the holding surface 20a.

[0034] The wafer 11 to be cut by the cutting device 2 is placed on the holding surface 20a of the chuck table 20. At this time, the position of the wafer 11 is adjusted so that a wafer center line 17 (see FIG. 1(B)) connecting the center 11e of the first surface 11a and the center 11f of the second surface 11b of the wafer 11 coincides with a first rotation axis 24c of the chuck table 20. Then, when a negative pressure generated by a suction source is applied to the wafer 11, the wafer 11 is suction-held by the chuck table 20. In this way, the chuck table 20 can hold the wafer 11 placed on the holding surface 20a and can rotate around the first rotation axis 24c that intersects with the holding surface 20a.

[0035] The rotary drive mechanism and the chuck table 20 are supported by an X1-axis moving plate (not shown). The X1-axis moving plate is configured to be movable along the X1-axis direction by an X1-axis moving mechanism (not shown) having a ball screw.

[0036] A cutting unit 8 for cutting the wafer 11 held by the chuck table 20 is disposed in the space inside the exterior panel 6. The cutting device 2 of this embodiment has one cutting unit 8. However, the cutting device 2 may have a parallel dual structure including two cutting units 8 arranged in mirror symmetry with respect to the X1Z1 plane, like a left and right hand.

[0037] 3 is a plan view schematically showing the chuck table 20 that holds the wafer 11 and the cutting unit 8. The cutting unit 8 has a spindle housing 10 whose longitudinal direction is arranged substantially parallel to the Y1 axis direction. A portion of a cylindrical spindle 12 is rotatably accommodated within the spindle housing 10.

[0038] The longitudinal direction of the spindle 12 is arranged along the Y1-axis direction. That is, the spindle 12 is arranged along the X1Y1 plane. A rotation drive source such as a motor (not shown) is connected to the vicinity of the base end of the spindle 12.

[0039] 3, a cutting blade 14 having an annular cutting edge portion 16 is attached to the tip of the spindle 12. The cutting edge portion 16 has an annular first side surface 16a, an annular second side surface 16b opposite the first side surface 16a, and a third side surface 16c between the first side surface 16a and the second side surface 16b. The cutting edge portion 16 is a member in which abrasive grains made of, for example, diamond or the like are dispersed and fixed by a binder such as metal, resin, or ceramic.

[0040] When the spindle 12 is rotated by a rotary drive source such as a motor, the cutting blade 14 also rotates integrally. The straight line that serves as the center of rotation at this time is defined as the second rotation axis 28. That is, the cutting unit 8 has the spindle 12 aligned along the second rotation axis 28, and the cutting blade 14 can be attached to the tip of the spindle 12, and the spindle 12 with the cutting blade 14 attached to the tip can rotate around the second rotation axis 28.

[0041] 1, a camera unit 34 is fixed to one side of the spindle housing 10. The camera unit 34 has a light source (not shown) such as an LED (Light Emitting Diode), an optical system (not shown) including a condenser lens, and a solid-state image sensor (not shown). The image obtained by the camera unit 34 capturing an image of the wafer 11 is used for alignment, kerf checking, and the like. The camera unit 34 can also function as a measurement unit, as will be described in detail later.

[0042] The spindle housing 10 and the camera unit 34 are fixed to the lower end of a Z1-axis moving plate 18. The Z1-axis moving plate 18 can be moved along the Z1-axis direction by a Z1-axis moving mechanism (not shown) having a ball screw. The Z1-axis moving mechanism is fixed to a Y1-axis moving plate (not shown).

[0043] The Y1-axis moving plate can be moved along the Y1-axis direction by a Y1-axis moving mechanism (not shown) having a ball screw. The positions of the cutting blade 14 and the camera unit 34 in the Y1-axis and Z1-axis directions are adjusted by the Y1-axis moving mechanism and the Z1-axis moving mechanism.

[0044] The position in the Z1-axis direction of the lower end of the cutting edge portion 16 of the cutting blade 14, which rotates at high speed around the spindle 12, is also adjusted by the Z1-axis movement mechanism, and the position in the Y1-axis direction of the lower end of this cutting edge portion 16 is also adjusted by the Y1-axis movement mechanism.

[0045] That is, the relative positions of the cutting unit 8 (cutting blade 14, cutting edge portion 16) and the chuck table 20 (wafer 11) in the X1-axis direction are adjusted by the X1-axis movement mechanism described above. The relative positions of the cutting unit 8 (cutting blade 14, cutting edge portion 16) and the chuck table 20 (wafer 11) in the Y1-axis direction are adjusted by the Y1-axis movement mechanism. The relative positions of the cutting unit 8 (cutting blade 14, cutting edge portion 16) and the chuck table 20 (wafer 11) in the Z1-axis direction are adjusted by the Z1-axis movement mechanism.

[0046] In other words, the cutting device 2 includes a first movement mechanism (Y1-axis movement mechanism) that moves the cutting unit 8 and the chuck table 20 relatively in a first direction (Y1-axis direction) that is parallel to the second rotation axis 28. Furthermore, the cutting device 2 includes a second movement mechanism (X1-axis movement mechanism) that moves the cutting unit 8 and the chuck table 20 relatively in a second direction (X1-axis direction) that is parallel to the holding surface 20a of the chuck table 20 and perpendicular to the first direction (Y1-axis direction).

[0047] A touch panel display 32 is provided on the front surface 6a of the exterior panel 6 of the cutting device 2. The touch panel display 32 serves as both an input device for an operator to input instructions to a controller (described later) and a display device for displaying images acquired by the camera unit 34, a display window that displays processing conditions, a GUI (Graphical User Interface), etc.

[0048] A cassette mounting table 6b is provided near the front surface 6a. A cassette (not shown) containing one or more wafers 11 is mounted on the cassette mounting table 6b. The cassette mounting table 6b can be moved along the Z1-axis direction by an elevator (not shown). The elevator adjusts the height of the cassette mounting table 6b, thereby adjusting the height of the wafers 11 being carried in and out of the cutting device 2 by the transport mechanism.

[0049] The cutting device 2 also has one or more transport mechanisms (not shown) that can transport the wafer 11 to the chuck table 20, etc. The wafer 11 may be transported to the chuck table 20 manually by an operator. In this case, the transport mechanism that transports the wafer 11 can be omitted.

[0050] The cutting device 2 includes a controller (control unit) 50 that controls each of the components. The cutting unit 8, the X1-axis movement mechanism (second movement mechanism), the Y1-axis movement mechanism (first movement mechanism), the Z1-axis movement mechanism, the camera unit (measurement unit) 34, the chuck table 20, the touch panel display 32, etc. are controlled by the controller 50.

[0051] The controller 50 is configured by a computer including, for example, a processor represented by a CPU (Central Processing Unit) and a memory. The memory includes a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a flash memory, an HDD (Hard Disk Drive), or an SSD (Solid State Drive).

[0052] The auxiliary storage device stores software including a predetermined program. The functions of the controller 50 are realized by operating a processor or the like in accordance with this program. Further details of the configuration, functions, etc. of the controller 50 will be described later.

[0053] The procedure for edge trimming the wafer 11 using the cutting device 2 begins by suction-holding the wafer 11 on the chuck table 20. Then, the spindle 12 of the cutting unit 8 is rotated to start rotating the cutting blade 14 around the center line of the cutting edge (second rotation axis 28). Here, the first side surface 16a of the cutting edge portion 16 of the cutting blade 14 is positioned closer to the wafer 11 than the second side surface 16b.

[0054] In general edge trimming processing, the cutting blade 14 and the chuck table 20 are positioned so that the center line of the cutting edge (second rotation axis 28) is perpendicular to the rotation center of the chuck table 20 (first rotation axis 24c), and the cutting blade 14 is then cut into the peripheral edge of the wafer 11.

[0055] After the cutting blade 14 cuts into the peripheral edge of the wafer 11, the chuck table 20 is slowly rotated while the spatial position of the cutting blade 14, which is rotating at high speed, is kept substantially fixed. Therefore, during cutting, the wafer 11 comes into contact with not only the third side surface 16c of the cutting edge portion 16 but also the first side surface 16a. This has caused problems such as chipping being likely to occur in the portion of the wafer 11 that comes into contact with the side surface of the cutting edge portion 16.

[0056] Therefore, angle trimming is performed. In angle trimming, the cutting blade 14 is positioned so that the center line of the cutting portion of the cutting blade 14 (second rotation axis 28) does not intersect with the rotation center of the chuck table 20 (first rotation axis 24c). In angle trimming, the side surface (first side surface 16a) of the cutting edge portion 16 of the cutting blade 14 is less likely to come into contact with the wafer 11, making it less likely that problems such as chipping of the wafer 11 will occur due to contact with the side surface of the cutting edge portion 16.

[0057] Unlike edge trimming that is not angle trimming, the width of the step portion (trim portion) 11g formed at the outer edge of the wafer 11 by angle trimming depends not only on the width of the outer surface (third side surface 16c) of the cutting blade 14 but also on the diameter of the cutting edge portion 16 of the cutting blade 14.

[0058] As angle trimming is performed sequentially on multiple wafers 11 using the cutting device 2, the cutting edge 16 of the cutting blade 14 wears down, gradually reducing its diameter. Therefore, during angle trimming, the width of the step 11g formed on the wafer 11 gradually decreases as the cutting edge 16 wears down, making it impossible to stably form step 11g of the intended width on multiple wafers 11. If step 11g with a sufficient width is not formed on the wafer 11, the chamfered portion 11d cannot be sufficiently removed from the wafer 11.

[0059] This point will be further explained. Fig. 5(A) is a side view schematically showing how the cutting edge portion 16d of the cutting blade 14 before it is worn cuts the outer peripheral edge of the wafer 11 to form a step portion (trim portion) 11g. Fig. 5(B) is a side view schematically showing how the cutting edge portion 16e of the cutting blade 14 that has worn to a certain extent cuts the outer peripheral edge of the wafer 11 to form a step portion (trim portion) 11g.

[0060] In each figure, for ease of explanation, only the outlines of the cutting edges 16d and 16e are drawn. Also, for ease of explanation, in FIG. 5(B), the outline of the cutting edge 16d before it is worn is shown by a dashed line. To form the step portion (trim portion) 11g at the same height position before and after the cutting edges 16d and 16e are worn, the height (position in the Z1-axis direction) of the cutting unit 8 is adjusted in accordance with the wear of the cutting edges 16d and 16e. As a result, the cutting edges 16d and 16e cut into the wafer 11 to the same height position.

[0061] In angle trimming, the wafer 11 is cut primarily by the outer peripheral side surfaces (third side surfaces 16c) of the cutting edges 16d and 16e as the chuck table 20 rotates. The worn cutting edge 16e has a smaller diameter, a larger curvature in its outer shape, and a smaller radius of curvature than the original cutting edge 16d. Therefore, the width of a step portion (trimmed portion) 11g formed on the wafer 11 decreases as the cutting edges 16d and 16e wear.

[0062] Further explanation will be given using plan views. Fig. 6(A) is a plan view schematically showing how the wafer 11 is cut by the cutting edge portion 16d before it is worn to form the step portion 11g, and Fig. 6(B) is a plan view schematically showing how the wafer 11 is cut by the worn cutting edge portion 16e to form the step portion 11g.

[0063] FIG. 6(A) illustrates an inner peripheral edge 11h of a step portion 11g formed by the cutting edge portion 16d before it is worn. Meanwhile, FIG. 6(B) illustrates an inner peripheral edge 11i of the step portion 11g formed by the worn cutting edge portion 16e. For ease of explanation, FIG. 6(B) also illustrates the inner peripheral edge 11h in the case where the step portion 11g is formed by the cutting edge portion 16d before it is worn by a dashed line. As can be seen from FIG. 6(B), when the step portion 11g is formed by the cutting edge portion 16e that has been worn down and reduced in diameter, the width of the step portion 11g becomes smaller.

[0064] Therefore, in the cutting device 2 and cutting method according to this embodiment, angle trimming of the wafer 11 is performed according to the procedure described below so that a step portion 11g is formed with sufficient width while accommodating wear of the cutting edge portion 16 of the cutting blade 14.

[0065] That is, the width of the step portion 11g formed on the wafer 11 by the cutting blade 14 is detected, and the position of the cutting blade 14 and the like is adjusted based on the measured width value. After that, the angle trimming of the wafer 11 may be resumed by the cutting blade 14 whose position has been adjusted, or angle trimming may be performed on another wafer 11. Such angle trimming is mainly realized by the function of the controller 50.

[0066] The cutting device 2 according to this embodiment will be further described, focusing on the configuration, function, and operation of the cutting device 2 that address wear of the cutting edge portion 16 of the cutting blade 14. As shown in FIG. 1, the controller 50 includes a target memory unit 52 that stores a target value for the width of the step portion 11g to be formed on the wafer 11 by the cutting unit 8. The target value for the width of the step portion 11g may be registered in the target memory unit 52, for example, before the wafer 11 is loaded into the cutting device 2.

[0067] The target value stored in the target storage unit 52 is determined to be, for example, a value that prevents a knife-edge shape due to the chamfered portion 11d from occurring when the wafer 11 on which the step portion 11g has been formed by edge trimming is ground by a grinding device. The target storage unit 52 may store an ideal value for the width of the step portion 11g as the target value, or may store a numerical range that is acceptable for the width of the step portion 11g as the target value. When edge trimming is performed on multiple wafers 11 of the same type in the cutting device 2, the target value only needs to be registered once.

[0068] The controller 50 includes a calculation unit 54 that calculates correction values ​​for the first moving mechanism and the second moving mechanism based on the measurement value obtained by measuring the width of the step portion 11g of the wafer 11 with the measurement unit and the target value stored in the target memory unit 52.

[0069] After the cutting unit 8 forms the step portion 11g at the outer peripheral edge of the wafer 11, the controller 50 (calculation unit 54) uses the measurement unit to measure the width of the step portion 11g of the wafer 11. For example, the controller 50 (calculation unit 54) controls the camera unit 34 as the measurement unit to capture an image of the vicinity of the step portion 11g of the wafer 11, and measures the width of the step portion 11g that appears in the captured image.

[0070] 7A is a cross-sectional view that schematically shows how the vicinity of the step portion 11g of the wafer 11 is imaged by the camera unit 34. The camera unit (measurement unit) 34 is moved above the step portion 11g of the wafer 11, and while the camera unit 34 is imaging the wafer 11, the chuck table 20 is rotated around the first rotation axis 24c. This allows a plurality of captured images that capture the step portion 11g.

[0071] Then, the controller 50 (calculation unit 54) detects the inner peripheral edge of the step portion 11g and the outer peripheral edge of the wafer 11 that appear in each captured image. For example, an area in the captured image where the contrast changes significantly is detected as the inner peripheral edge of the step portion 11g or the outer peripheral edge of the wafer 11. Then, the distance between the inner peripheral edge of the step portion 11g and the outer peripheral edge of the wafer 11 is identified as the width of the step portion 11g.

[0072] The measuring unit used by the calculation unit 54 to determine the width of the step portion 11g is not limited to the camera unit 34. The cutting device 2 may be provided with a measuring unit for determining the width of the step portion 11g in addition to the camera unit 34. The measuring unit may be, for example, a laser displacement meter, a back pressure sensor, or the like. The measuring unit may be supported by the spindle housing 10, for example, in the same manner as the camera unit 34.

[0073] 7(B) is a cross-sectional view that schematically shows how the width of the step portion 11g is determined by a laser displacement meter 36 that functions as a measurement unit. The laser displacement meter 36 includes a laser oscillator 38 and a measurement head 40 that irradiates the wafer 11 with a laser beam 42 that originates from the laser oscillator 38 and travels through a light-guiding member such as an optical fiber.

[0074] The measurement head 40 is formed with a downward-facing projection window, and the laser beam 42 is emitted from this projection window toward the wafer 11. The laser displacement meter 36 irradiates the laser beam 42 from the measurement head 40 to each point on the upper surface (first surface 11a) of the wafer 11.

[0075] The laser displacement meter 36 receives the laser beam 42 reflected by the wafer 11. A light-receiving window is formed in the measurement head 40, aligned with the light-projecting window. The reflected laser beam 42 is received by the measurement head 40 at this light-receiving window. The laser beam 42 received by the measurement head 40 travels through a light-guiding member such as an optical fiber, and is converted into an electrical signal by a light-receiving element (such as a CCD sensor or a CMOS sensor) provided in the laser oscillator 38.

[0076] The characteristics of the received laser beam 42 change depending on the height of each point on the top surface of the wafer 11 that reflected the laser beam 42, and so the height position of each point can be identified from this electrical signal. Then, the controller 50 (calculation unit 54) identifies the shape of the step portion 11g from the height distribution on the top surface of the wafer 11 obtained by the laser displacement meter 36, and identifies the width of the step portion 11g.

[0077] Thereafter, the calculation unit 54 calculates correction values ​​for each of the first moving mechanism and the second moving mechanism based on the measurement value obtained by measuring the width of the step portion 11g of the wafer 11 with the measurement unit and the target value stored in the target storage unit 52. For example, the calculation unit 54 calculates the difference between the measured width and the target value, and calculates the correction value so that this difference approaches zero.

[0078] The controller 50 further includes an adjustment unit 56. The adjustment unit 56 operates the first movement mechanism and the second movement mechanism based on the correction value calculated by the calculation unit 54, and adjusts the relative position between the cutting unit 8 and the chuck table 20. That is, the adjustment unit 56 adjusts the relative positional relationship between the wafer 11 and the cutting edge portion 16 of the cutting blade 14 that constitutes the cutting unit 8, in order to cut the peripheral edge portion of the wafer 11.

[0079] Here, an example of calculation of the correction value performed by the controller 50 (calculation unit 54) will be described. The calculation of the correction value may be performed, for example, based on an angle (cutting angle) that characterizes the angle trim. This angle will be described using FIG. 3. This angle is the angle formed by the first line 30 connecting the first rotation axis 24c and a reference point on the second rotation axis 28 that represents the position of the cutting edge portion 16 of the cutting blade 14, on a plane (X1Y1 plane) parallel to the holding surface 20a of the chuck table 20, and the second rotation axis 28.

[0080] This angle (cutting angle) will be described in further detail. The reference point representing the position of the cutting edge portion 16 of the cutting blade 14 is a point imagined on the second rotation axis 28. For example, it is the center 18a of the first side surface 16a of the cutting edge portion 16. However, the reference point is not limited to this, and it may also be the center 18b of the second side surface 16b of the cutting edge portion 16.

[0081] Alternatively, the reference point may be a point on the second rotation axis 28 that is closest to the first rotation axis 24c among the components of the cutting unit 8. In this case, the reference point is the outermost point of the flange member that fixes the cutting blade 14 to the tip of the spindle 12. In this way, the reference point may be set at a point away from the cutting edge portion 16.

[0082] In addition, in a plane parallel to the first surface 11a of the wafer 11 and including the second rotation axis 28, a line connecting the wafer center line 17 (first rotation axis 24c) and a reference point (the center 18a of the first side surface 16a of the cutting edge portion 16) is defined as a first line 30. In this case, the angle formed by the first line 30 and the second rotation axis 28 (cutting portion center line) is defined as the cutting angle.

[0083] In angle trimming, the cutting angle is set to a value other than zero. For example, before the cutting edge 16 of the cutting blade 14 is worn, the magnitude of the cutting angle is set to α, as shown in Figure 3. The width of the step 11g formed on the outer periphery of the wafer 11 varies depending on the cutting angle, and when the cutting angle is relatively large, a step 11g with a larger width is formed on the wafer 11 compared to when the cutting angle is relatively small.

[0084] Then, the controller 50 (calculation unit 54) calculates an angle correction value for correcting the cutting angle based on the cutting angle, the measurement value of the width of the step portion 11g obtained by the measurement unit, and the target value stored in the target memory unit 52.

[0085] For example, the memory unit of the controller 50 may store relationships between, for example, the cutting angle, cutting depth, the diameter of the cutting edge portion 16 of the cutting blade 14, and the width of the step portion 11g formed on the wafer 11, and these relationships may be referenced when calculating the angle correction value. In order to deal with the decrease in the width of the step portion 11g due to wear of the cutting edge portion 16 of the cutting blade 14, it is possible to increase the cutting angle to increase the width of the step portion 11g. The calculation unit 54 calculates an angle correction value that can offset the decrease in the width of the step portion 11g to a certain extent.

[0086] Here, when actually changing the cutting angle in the cutting device 2, the first movement mechanism (Y1-axis movement mechanism) and the second movement mechanism (X1-axis movement mechanism) are operated to change the relative positions of the cutting unit 8 and the chuck table 20. Based on the angle correction value, the calculation unit 54 calculates a correction value for each of the first movement mechanism (Y1-axis movement mechanism) that moves them relatively in the first direction (Y1-axis direction) and the second movement mechanism (X1-axis movement mechanism) that moves them relatively in the second direction (X1-axis direction).

[0087] The procedure for calculating the correction value by the calculation unit 54 described above will be summarized below. The calculation unit 54 calculates the difference between the measured value of the width of the step portion 11g and the target value stored in the target storage unit 52, and evaluates the magnitude of this difference. Then, the calculation unit 54 calculates an angle correction value to reduce this difference so that the difference falls within an allowable range. The calculation unit 54 calculates the correction values ​​for the first and second moving mechanisms based on the angle correction value. However, the calculation unit 54 may also calculate the correction values ​​for the first and second moving mechanisms so that the width of the step portion 11g approaches the target value without calculating the angle correction value.

[0088] In the procedure for calculating the correction value described above, a point that overlaps with the second rotation axis 28 is used as a reference point that indicates the position of the cutting edge portion 16 of the cutting blade 14, and the cutting angle is derived from this reference point. However, the method for defining the cutting angle is not limited to this. For example, a point that does not overlap with the second rotation axis 28 may be used as the reference point, and the cutting angle may be derived from such a reference point to calculate the correction value.

[0089] Regardless of where the reference point is defined and the cutting angle is specified, the cutting angle can be adjusted in the same way as long as the position of the reference point can be used as information indicating the position of the cutting edge portion 16 of the cutting blade 14. Even when the cutting angle is specified and a correction value is calculated using a point that does not overlap with the second rotation axis 28 as the reference point, the correction value is calculated in the same way as when the cutting angle is specified and a point that overlaps with the second rotation axis 28 as the reference point.

[0090] Therefore, there is no difference in the final calculated correction value between a case where a point that does not overlap with the second rotation axis 28 is used as the reference point, a cutting angle is specified, and a case where a correction value is calculated, a point that overlaps with the second rotation axis 28 is used as the reference point, a cutting angle is specified, and a correction value is calculated. Therefore, even when a point that does not overlap with the second rotation axis 28 is used as the reference point, a cutting angle is specified, and a correction value is calculated, the point that overlaps with the second rotation axis 28 is used as the reference point.

[0091] Furthermore, the calculation unit 54 may calculate the correction values ​​for each of the first and second moving mechanisms so that the width of the step portion 11g approaches the target value, without calculating the angle correction value. For example, the memory unit of the controller 50 stores the relationship between the relative positions of the cutting unit 8 and the chuck table 20 in the first direction (Y1-axis direction), the relative positions in the second direction (X1-axis direction), and the width of the step portion 11g formed on the wafer 11. In this case, the calculation unit 54 may derive the correction values ​​for each of the first and second moving mechanisms from the measured value of the width of the step portion 11g measured by the measurement unit and this relationship.

[0092] 8 is a plan view schematically showing how the first moving mechanism and the second moving mechanism are operated based on the correction value to adjust the relative position between the cutting unit 8 and the chuck table 20. This adjustment of the relative position is performed by the adjustment unit 56 of the controller 50.

[0093] For example, the calculation unit 54 calculates an angle correction value to change the cutting angle from α shown in Fig. 3 to β shown in Fig. 8, and calculates correction values ​​for each of the first and second moving mechanisms. The adjustment unit 56 of the controller 50 operates the first and second moving mechanisms based on the calculated correction values ​​for each of the first and second moving mechanisms.

[0094] 8, the adjustment unit 56 adjusts the relative position between the cutting unit 8 and the chuck table 20 in the second direction (X1-axis direction) according to the correction value of the second moving mechanism. Next, the adjustment unit 56 adjusts the relative position between the cutting unit 8 and the chuck table 20 in the first direction (Y1-axis direction) according to the correction value of the first moving mechanism. However, the relative position in the first direction may be adjusted first, and then the relative position in the second direction may be adjusted. Alternatively, the relative positions in the first direction and the second direction may be adjusted simultaneously.

[0095] The cutting device 2 according to this embodiment performs adjustment according to the procedure described above. If the width of the step portion 11g formed on the wafer 11 is insufficient, angle trimming may be performed again on the wafer 11 after the adjustment is completed in the cutting device 2. In this case, a step portion 11g of an appropriate width is re-formed on the outer periphery of the wafer 11. Alternatively, angle trimming may be performed on a new wafer 11 after the adjustment is completed in the cutting device 2. In this case, step portions 11g of an appropriate width will be formed on this new wafer 11 and on wafers 11 to be processed thereafter.

[0096] Therefore, with the cutting device 2 according to this embodiment, a step 11g with a sufficient width can be stably formed on the outer peripheral edge of the wafer 11 in edge trimming performed by angle trimming.

[0097] Next, a cutting method according to this embodiment, which is carried out by the cutting device 2, will be described. In this cutting method, the outer peripheral edge of the wafer 11, which has a chamfered portion 11d at its outer peripheral edge, is cut to form a step portion 11g at the outer peripheral edge. The following description can also be referred to as appropriate for an explanation of the functions, operation procedures, and usage of the cutting device 2. Similarly, the above-mentioned explanation of the cutting device 2 can also be referred to as appropriate for an explanation of the cutting method according to this embodiment. Figure 9 is a flowchart showing the flow of each step of the cutting method according to this embodiment. Each step will be described in detail below.

[0098] In the cutting method according to this embodiment, a first cutting step S10 is first performed. Fig. 4(A) is a plan view of the first cutting step S10. Fig. 4(B) is a cross-sectional view of the first cutting step S10 as viewed in the direction of arrow A1 in Fig. 4(A), and Fig. 4(C) is a side view of the first cutting step S10 as viewed in the direction of arrow A2 in Fig. 4(A).

[0099] 4(A) and 4(B), the second rotation axis 28, which is the rotation center of the spindle 12, is indicated by a two-dot chain line parallel to the Y1 axis direction. Also, the first rotation axis 24c, which is the rotation center of the chuck table 20, is indicated by a dot in FIG. 4(A) and by a two-dot chain line parallel to the Z1 axis direction in FIG. 4(B).

[0100] In the first cutting step S10, the wafer 11 is placed on the holding surface 20a of the chuck table 20, which is rotatable around a first rotation axis 24c that passes through the central region of the holding surface 20a, and the wafer 11 is held by the chuck table 20. Here, the cutting unit 8 has a spindle 12 along a second rotation axis 28 that is positioned so as not to intersect with the first rotation axis 24c, as described above, and is equipped with a cutting blade 14 attached to the tip of the spindle 12.

[0101] Then, in the first cutting step S10, the cutting blade 14 of the cutting unit 8 is rotated around the second rotation shaft 28 to cut into the chamfered portion 11d of the wafer 11, and the chuck table 20 is rotated around the first rotation shaft 24c. This cuts the outer peripheral edge of the wafer 11 to form a step portion 11g (first step portion). Figures 4(A), 4(B), and 4(C) show the step portion 11g formed in the wafer 11.

[0102] In the cutting method according to this embodiment, a measuring step S20 is performed simultaneously with or after the first cutting step S10 to measure the width of the step portion 11g (first step portion) formed on the wafer 11 to obtain a measurement value. In the measuring step S20, a measuring unit provided in the cutting device 2 is used.

[0103] 7(A) is a cross-sectional view schematically showing the measuring step S20 according to the first example. When the measuring step S20 is performed using the camera unit 34 as the measuring unit, first, the camera unit 34 is positioned above the step portion 11g formed on the wafer 11 by the Y1-axis movement mechanism and the Z1-axis movement mechanism. Then, rotation of the chuck table 20 around the first rotation axis 24c is started.

[0104] Thereafter, the camera unit 34 sequentially captures images of the wafer 11, and acquires captured images showing the step portion 11g. The controller 50 of the cutting device 2 detects the step portion 11g from the captured images, and detects the width of the step portion 11g. This allows the measurement value of the width of the step portion 11g to be obtained.

[0105] 7(B) is a cross-sectional view schematically showing the measurement step S20 according to the second example. When the laser displacement meter 36 is used as the measurement unit, the measurement head 40 is positioned above the step portion 11g formed on the wafer 11. Then, rotation of the chuck table 20 around the first rotation axis 24c is started.

[0106] Thereafter, the laser displacement meter 36 sequentially measures the height of each point on the top surface of the wafer 11 to obtain the height distribution of the top surface of the wafer 11. The controller 50 of the cutting device 2 identifies the position of the step portion 11g from the obtained height distribution and detects the width of the step portion 11g. This provides a measured value of the width of the step portion 11g.

[0107] After the measurement step S20 is performed, a correction step S30 is performed in which the relative positions of the chuck table 20 and the cutting blade 14 are corrected based on the measurement value obtained in the measurement step S20 and the target width of the stepped portion.

[0108] Then, after the correction step S30, a second cutting step S40 is performed. FIG. 8 shows a schematic diagram of the second cutting step S40 being performed. In the second cutting step S40, the cutting blade 14 is rotated around the second rotation axis 28 to cut into the chamfered portion 11d of the wafer 11, and the chuck table 20 is rotated around the first rotation axis 24c. This cuts the first step portion at the outer peripheral edge of the wafer 11 to form a second step portion. In other words, the step portion 11g is reformed.

[0109] Here, in the correction step S30, a first correction value is calculated to correct the first movement mechanism (Y1-axis movement mechanism) that relatively moves the spindle 12 (cutting blade 14) and the chuck table 20 in a direction parallel to the second rotation axis 28. Also, a second correction value is calculated to correct the second movement mechanism (X1-axis movement mechanism) that relatively moves the spindle 12 (cutting blade 14) and the chuck table 20 in a direction parallel to the holding surface 20a and perpendicular to the second rotation axis 28 (X1-axis direction).

[0110] Then, both the first correction value and the second correction value are calculated based on the measured value and the target value of the width of the step portion 11g, and then the operation of the first moving mechanism is corrected using the first correction value, and the operation of the second moving mechanism is corrected using the second correction value.

[0111] In the correction step S30, an angle correction value for the cutting angle may be calculated, and the first and second correction values ​​may be calculated based on the angle correction value. As described above, the cutting angle is defined as the angle formed by the first line 30 connecting the first rotation axis 24c and a reference point on the second rotation axis 28 that represents the position of the cutting edge portion 16 of the cutting blade 14, and the second rotation axis 28, in a plane (X1Y1 plane) parallel to the holding surface 20a of the chuck table 20. For example, the reference point is defined as the center 18a of the first side surface 16a of the cutting edge portion 16. Alternatively, the reference point may be defined as the center 18b of the second side surface 16b of the cutting edge portion 16.

[0112] Then, in the correction step S30, an angle correction value for correcting the cutting angle is calculated based on this cutting angle, the measured value of the width of the step portion 11g, and the target value of the width of the step portion 11g, and the first correction value and the second correction value may be calculated based on the angle correction value.

[0113] According to the cutting method of this embodiment described above, when the width of the step portion 11g formed on the wafer 11 becomes smaller due to wear of the cutting edge portion 16 during angle trimming, a correction is made to increase the width of the step portion 11g. Therefore, step portions 11g can be stably formed on multiple wafers 11 with the planned width.

[0114] The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the cutting method according to the above-described embodiment, a first step portion is formed on one wafer 11, and then adjustment is made based on the width of the first step portion. The wafer 11 is then cut again to form a second step portion of an appropriate width. However, the cutting method according to one aspect of the present invention is not limited to this.

[0115] That is, the cutting method according to one aspect of the present invention is not limited to the case where the wafer 11 on which the first step portion is formed and the wafer 11 on which the second step portion is formed are the same wafer 11. The wafer 11 on which the first step portion is formed and the wafer 11 on which the second step portion is formed may be different wafers 11. In this case, it is preferable to form the first step portion on a dummy wafer dedicated to adjustment, and after adjustment, form the second step portion on the wafer 11 that is the target of actual processing.

[0116] The flow of each step of the cutting method according to one aspect of the present invention in this case will be described below. That is, this cutting method is a cutting method for cutting the outer peripheral edges of a first wafer and a second wafer, each of which has a chamfered portion at its outer peripheral edge, to form a step portion at each outer peripheral edge.

[0117] In the first cutting step S10, the first wafer is held by the chuck table 20, and the cutting blade 14 is caused to cut into the chamfered portion of the first wafer while being rotated about the second rotation shaft 28. At the same time, the chuck table 20 is rotated about the first rotation shaft 24c to cut the outer peripheral edge of the first wafer and form a first step portion.

[0118] Simultaneously with or after the first cutting step S10, a measuring step S20 is performed in which the width of the first step portion formed on the first wafer is measured to obtain a measurement value. Then, a correction step S30 is performed in which the relative positions of the chuck table 20 and the cutting blade 14 are corrected based on the measurement value obtained in the measuring step S20 and the target width of the step portion 11g.

[0119] After the correction step S30, the second cutting step S40 is performed. In the second cutting step S40, the first wafer is removed from the chuck table 20, and the second wafer is placed on the holding surface 20a of the chuck table 20 and held by the chuck table 20. Then, the cutting blade 14 is rotated around the second rotation axis 28 to cut into the chamfered portion of the second wafer, and the chuck table 20 is rotated around the first rotation axis 24c. This cuts the outer peripheral edge of the second wafer and forms a second step portion.

[0120] In the correction step S30, a first correction value for correcting the first movement mechanism and a second correction value for correcting the second movement mechanism are both calculated based on the measured values ​​and the target values. Then, the first movement mechanism is corrected using the first correction value, and the second movement mechanism is corrected using the second correction value.

[0121] When the second wafer is cut using this procedure, a step portion 11g of an appropriate width is formed on the second wafer with the relative position of the chuck table 20 and the cutting blade 14 adjusted. In this way, if a wafer 11 different from the wafer 11 to be actually processed is used to calculate the correction value for adjustment, there is no need to re-process the wafer 11 to be actually processed after adjusting it based on the correction value.

[0122] The structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0123] 11 wafers 11a 1st surface 11b 2nd surface 11c notch 11d Chamfered part 11e center 11f center 11g Step 11h inner edge 11i inner rim 13 Planned division line 15 devices 17 Wafer Centerline 2 Cutting equipment 4 Base 6 Exterior Panels 6a front 6b Cassette stand 8 Cutting Unit 10 Spindle housing 12 spindles 14 Cutting blade 16 Cutting edge 16a 1st side 16b Second side 16c 3rd side 16d cutting edge 16e Cutting edge 18 Z1 axis moving plate 18a center 18b center 20 Chuck table 20a Holding surface 22 Frame 22a Top side 22b Recess 22c Suction path 24 Porous plate 24a Top side 24c First rotation axis 28 Second rotation axis 30 1st straight line 32 Touch panel display 34 Camera Unit 36 Laser displacement meter 38 Laser Oscillator 40 Measuring Head 42 Laser Beam 50 Controllers 52 Target memory section 54 Calculation section 56 Adjustment section

Claims

1. A cutting device for cutting a peripheral edge of a wafer having a chamfered portion at the peripheral edge to form a step portion, a chuck table capable of holding a wafer placed on a holding surface and rotatable about a first rotation axis intersecting the holding surface; a cutting unit having a spindle along a second rotation axis that does not intersect with the first rotation axis, a cutting blade that can be attached to a tip of the spindle, and the spindle with the cutting blade attached to the tip can be rotated around the second rotation axis; a measuring unit for measuring the width of a step portion of the wafer that is held on the chuck table and has been cut by the cutting unit to form the step portion; a first moving mechanism that moves the cutting unit and the chuck table relatively in a first direction parallel to the second rotation axis; a second moving mechanism that relatively moves the cutting unit and the chuck table in a second direction that is parallel to the holding surface and perpendicular to the first direction; a controller; The controller a target storage unit that stores a target value of the width of the step portion to be formed on the wafer by the cutting unit; a calculation unit that calculates correction values ​​for the first movement mechanism and the second movement mechanism based on the measurement value obtained by measuring the width of the step portion of the wafer with the measurement unit and the target value; and an adjustment unit that operates the first movement mechanism and the second movement mechanism based on the correction value calculated by the calculation unit, and adjusts the relative positions of the cutting unit and the chuck table.

2. The calculation unit of the controller In a plane parallel to the holding surface of the chuck table, a reference point which is a point on the second rotation axis and indicates the position of the cutting edge portion of the cutting blade, and a first line connecting the first rotation axis and the second rotation axis can be calculated as a cutting angle, 2. The cutting device according to claim 1, wherein an angle correction value for correcting the cutting angle is calculated based on the cutting angle, the measurement value, and the target value, and the correction values ​​of the first moving mechanism and the second moving mechanism are calculated based on the angle correction value.

3. A cutting method for cutting an outer circumferential edge of a wafer having a chamfered portion at the outer circumferential edge to form a step portion at the outer circumferential edge, comprising: a first cutting step in which the wafer is placed on a holding surface of a chuck table rotatable about a first rotation axis passing through a central region of the holding surface, the wafer is held by the chuck table, and a cutting unit has a spindle along a second rotation axis that does not intersect with the first rotation axis, and the cutting blade is attached to the tip of the spindle, and the cutting blade is rotated about the second rotation axis to cut into the chamfered portion of the wafer, and the chuck table is rotated about the first rotation axis to cut the outer peripheral edge of the wafer and form a first step portion; a measuring step of measuring a width of the first step portion formed on the wafer simultaneously with or after the first cutting step to obtain a measurement value; a correcting step of correcting the relative position of the chuck table and the cutting blade based on the measurement value obtained in the measuring step and a target width; a second cutting step, after the correction step, of cutting the first step portion at the outer peripheral edge of the wafer to form a second step portion by rotating the cutting blade about the second rotation axis while cutting into the chamfered portion of the wafer and rotating the chuck table about the first rotation axis, In the correction step, a first correction value for correcting a first moving mechanism that relatively moves the spindle and the chuck table in a direction parallel to the second rotation axis, and a second correction value for correcting a second moving mechanism that relatively moves the spindle and the chuck table in a direction parallel to the holding surface and perpendicular to the second rotation axis are both calculated based on the measurement value and the target value, and the first moving mechanism is corrected with the first correction value and the second moving mechanism is corrected with the second correction value.

4. A cutting method for forming a step portion at each of the outer peripheral edges of a first wafer and a second wafer, the outer peripheral edges of which have chamfered portions, by cutting the outer peripheral edges, the step portion being formed at each of the outer peripheral edges, the method comprising: a first cutting step in which the first wafer is placed on a holding surface of a chuck table rotatable about a first rotation axis passing through a central region of the holding surface, the first wafer is held by the chuck table, and a cutting unit has a spindle along a second rotation axis that does not intersect with the first rotation axis, and the cutting blade is attached to the tip of the spindle, and the cutting blade is rotated about the second rotation axis to cut into the chamfered portion of the first wafer, and the chuck table is rotated about the first rotation axis to cut the outer peripheral edge of the first wafer and form a first step portion; a measuring step of measuring a width of the first step portion formed on the first wafer simultaneously with or after the first cutting step to obtain a measurement value; a correcting step of correcting the relative position of the chuck table and the cutting blade based on the measurement value obtained in the measuring step and a target width; a second cutting step of, after the correction step, placing the second wafer on the holding surface of the chuck table, holding the second wafer with the chuck table, and cutting the outer peripheral edge of the second wafer to form a second step portion by rotating the cutting blade about the second rotation axis while causing it to cut into the chamfered portion of the second wafer and rotating the chuck table about the first rotation axis, In the correction step, a first correction value for correcting a first moving mechanism that relatively moves the spindle and the chuck table in a direction parallel to the second rotation axis, and a second correction value for correcting a second moving mechanism that relatively moves the spindle and the chuck table in a direction parallel to the holding surface and perpendicular to the second rotation axis are both calculated based on the measurement value and the target value, and the first moving mechanism is corrected with the first correction value and the second moving mechanism is corrected with the second correction value.

5. In the correction step, In a plane parallel to the holding surface of the chuck table, a reference point that is a point on the second rotation axis and indicates the position of the cutting edge portion of the cutting blade is connected to the first rotation axis, and the angle formed by the second rotation axis is calculated as a cutting angle; 5. The cutting method according to claim 3, further comprising: calculating an angle correction value for correcting the cutting angle based on the cutting angle, the measurement value, and the target value; and calculating the first correction value and the second correction value based on the angle correction value.

Images