Method for cutting a workpiece, method for manufacturing a semiconductor device, and cutting apparatus

Abstract

The present invention provides a method for cutting a workpiece, a method for manufacturing a semiconductor device, and a cutting apparatus that can reduce variations in cutting depth caused by differences in cutting volume when a recess is formed on the planned cutting line of the workpiece. [Solution] The method includes a holding step of holding the wafer (100) on the holding surface (11) of the chuck table (10), and a cutting step of cutting the annular region (109) of the wafer (100) by moving the chuck table (10) and the cutting blade (21) relative to each other while the cutting blade (21) is set to cut into the annular region (109), which is the cutting line of the wafer (100). If the wafer (100) has a notch (110) which is a recess that overlaps the annular region (109), the load on the cutting blade (21) is changed in the cutting step between the region corresponding to the notch (110) and the other regions.

Description

Technical Field

[0001] The present invention relates to a method for cutting a workpiece, a method for manufacturing a semiconductor device, and a cutting apparatus.

Background Art

[0002] In the manufacturing process of semiconductor devices and electronic components, a plate-shaped workpiece made of various materials such as a semiconductor wafer (hereinafter, may be simply referred to as a wafer) or a ceramic substrate is ground by a grinding wheel mounted on a spindle of a grinding apparatus to form a predetermined thickness (for example, see Patent Document 1). Thereafter, it is divided into individual device chips by a cutting blade mounted on a spindle of a cutting apparatus.

[0003] In such a manufacturing process, half-cut cutting for forming a groove having a predetermined depth may be performed. At that time, if a recess that becomes a recess is formed in the cutting planned line, the cutting depth becomes deeper due to a decrease in the cutting load at the recess position.

[0004] In addition, in a method of removing a chamfer portion from an outer peripheral edge portion by edge trimming a wafer having a chamfer portion (also referred to as a bevel portion), it is desired to cut at a uniform depth at the outer peripheral portion of the wafer (for example, see Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the notches indicating the crystal orientation have a smaller cutting volume, resulting in lower load and a deeper cut depth, which hinders uniform depth cutting. In such cases, the material may get caught during depth inspection, or the trim portion may be removed at different timings during grinding. Furthermore, if the workpiece is a bonded wafer, there is a possibility of cutting into the lower wafer.

[0007] Therefore, when forming grooves in a workpiece where recesses are formed along the planned cutting line, there is a problem to be solved: establishing a method for forming uniform cutting grooves even in the recesses.

[0008] The present invention has been made in view of the above, and aims to provide a method for cutting a workpiece, a method for manufacturing a semiconductor device, and a cutting apparatus that can reduce variations in cutting depth caused by differences in cutting volume when a recess is formed in the planned cutting line of the workpiece. [Means for solving the problem]

[0009] A cutting method for a workpiece according to one aspect of the present invention is a method for cutting a workpiece in which a cutting blade is driven into the workpiece to a predetermined depth and the workpiece is cut with the cutting blade along a predetermined cutting line set on the workpiece to form a cutting groove of the predetermined depth. The cutting method includes a holding step in which the workpiece is held on the holding surface of a chuck table. It also includes a cutting step in which, with a cutting blade having a cutting edge on its outer circumference mounted on the tip of a spindle driven into the predetermined cutting line of the workpiece, the chuck table and the cutting blade are moved relative to each other to cut the predetermined cutting line. The workpiece has a recess that overlaps the predetermined cutting line, and in the cutting step, the load on the cutting blade is changed between the region corresponding to the recess and other regions.

[0010] A method for manufacturing a semiconductor device chip according to one aspect of the present invention comprises a cutting step of cutting a semiconductor wafer in which a semiconductor device is formed in each region demarcated by a plurality of intersecting division lines on the surface and a notch is formed on the outer periphery, and the cutting line is set along the outer edge of the wafer. The method further comprises a grinding step of grinding the wafer after the cutting step, and a division step of dividing the wafer along the division line to manufacture a semiconductor device chip after the grinding step. The notch overlaps the cutting line, and in the cutting step, the load of the cutting blade is changed between the region in which the notch is formed and the other regions.

[0011] A cutting apparatus according to one aspect of the present invention is a cutting apparatus for cutting the outer edge of a disc-shaped wafer and removing the chamfered portion. The cutting apparatus comprises a chuck table having a rotation axis in a direction intersecting the holding surface and including a holding surface for holding the wafer, and a cutting unit comprising a spindle on which a cutting blade having a cutting edge on its outer circumference can be mounted. It also comprises a moving unit for moving the chuck table and the cutting unit relative to each other in a direction intersecting the holding surface, and a notch detection mechanism for detecting a notch position indicating the crystal orientation formed on the outer edge of the wafer held by the holding surface. Furthermore, it comprises a controller having memory and a processor for controlling the operation of the chuck table, the cutting unit, and the moving unit. The controller includes a correction command unit that changes the load on the cutting blade in the notch position region detected by the notch detection mechanism and other regions when cutting the wafer. [Effects of the Invention]

[0012] According to the present invention, when a recess is formed in the workpiece, it is possible to reduce variations in the depth of cut caused by differences in cutting volume. [Brief explanation of the drawing]

[0013] [Figure 1]This is a perspective view illustrating the workpiece (wafer) according to the first embodiment. [Figure 2] This is a perspective view illustrating an example of a cutting apparatus according to the first embodiment. [Figure 3] This figure illustrates an example of a detailed configuration of a cutting apparatus according to the first embodiment. [Figure 4] This is a diagram illustrating the holding step according to the first embodiment. [Figure 5] This is a diagram illustrating the cutting step according to the first embodiment. [Figure 6] This is a perspective view illustrating the cutting step according to the first embodiment. [Figure 7] This is a diagram illustrating the cutting step according to the first embodiment. [Figure 8] This is a perspective view illustrating another workpiece (bonded wafer) according to the first embodiment. [Figure 9] This figure illustrates the cutting step according to the second embodiment. [Figure 10] This is a perspective view illustrating the cutting step according to the second embodiment. [Modes for carrying out the invention]

[0014] The embodiments will be described below with reference to the drawings. (First Embodiment)

[0015] First, the configuration of the workpiece 2 to be machined will be described. In the present embodiment, the wafer 100 shown in FIG. 1 is used as the workpiece 2. FIG. 1 is a perspective view for explaining the workpiece (wafer) according to the first embodiment. As shown in FIG. 1, the wafer 100 as the workpiece 2 is a disk-shaped semiconductor wafer having a substrate such as silicon, sapphire, gallium arsenide, or SiC (silicon carbide). It has a device layer 103 on the surface 101 side of the substrate 104. The device layer 103 has a central region 105 and an outer peripheral surplus region 106 surrounding the central region 105. In the central region 105, semiconductor devices (hereinafter referred to as devices) 108 are formed in each region partitioned by a plurality of division planned lines 107 intersecting each other. The device 108 is an integrated circuit such as an IC (Integrated Circuit) or LSI (Large Scale Integration). Note that the outer peripheral surplus region 106 is a region that surrounds the central region 105 of the device layer 103 and in which the device 108 is not formed.

[0016] An annular region 109 is set in the outer peripheral surplus region 106. The annular region 109 is a region having a predetermined width in the central direction from the outer peripheral edge of the wafer 100 and is a target region for outer peripheral trimming. Note that the annular region 109 may coincide with the outer peripheral surplus region 106. Further, a notch 110, which is a V-shaped groove, is formed in the outer edge of the wafer 100. The notch 110 is a notch indicating the crystal orientation of the substrate 104. (In the following description, the notch 110 is referred to as the notch 110.) Note that the outer edge of the wafer 100 may be chamfered so that the center in the thickness direction protrudes most to the outer peripheral side and has a cross-sectional arc shape extending from the surface 101 to the back surface 102 of the substrate 104.

[0017] Next, a cutting device for grinding the workpiece 2 configured as described above will be described. FIG. 2 is a perspective view for explaining an example of a cutting device according to the first embodiment. Further, FIG. 3 is a diagram for explaining an example of a detailed configuration of the cutting device according to the first embodiment. As shown in FIG. 2, the cutting device 1 includes a chuck table 10 that sucks and holds the wafer 100, which is the workpiece 2, on the holding surface 11, a cutting unit 20 that is a processing unit for cutting the wafer 100 held by the chuck table 10 with a cutting blade 21, an imaging unit 26 (see FIG. 3) that images the wafer 100 held by the chuck table 10, and a controller 300.

[0018] Also, as shown in FIG. 3, the cutting device 1 includes a moving unit 40 that relatively moves the chuck table 10 with respect to the cutting unit 20. The moving unit 40 includes an X-axis moving unit 41 that feeds the chuck table 10 in the machining feed direction, which is the X-axis direction parallel to the horizontal direction, a Y-axis moving unit 42 that indexes and feeds the cutting unit 20 in the Y-axis direction parallel to the horizontal direction and orthogonal to the X-axis direction, a Z-axis moving unit 43 that feeds the cutting unit 20 in the cutting feed direction, which is the Z-axis direction parallel to the vertical direction and orthogonal to both the X-axis direction and the Y-axis direction, and a rotational moving unit 44 that rotates the chuck table 10 around an axis parallel to the Z-axis direction.

[0019] The X-axis moving unit 41 relatively feeds the chuck table 10 and the cutting unit 20 along the X-axis direction by moving the chuck table 10 in the X-axis direction, which is the machining feed direction. The Y-axis moving unit 42 relatively indexes and feeds the chuck table 10 and the cutting unit 20 along the Y-axis direction by moving the cutting unit 20 in the Y-axis direction, which is the indexing feed direction. The Z-axis moving unit 43 relatively feeds the chuck table 10 and the cutting unit 20 along the Z-axis direction by moving the cutting unit 20 in the Z-axis direction, which is the cutting feed direction. The rotational moving unit 44 is moved in the X-axis direction together with the chuck table 10 by the X-axis moving unit 41.

[0020] The X-axis moving unit 41, Y-axis moving unit 42, and Z-axis moving unit 43 each include a well-known ball screw rotatably mounted around its axis, a well-known motor that rotates the ball screw around its axis to move the chuck table 10 or cutting unit 20 in the X-axis, Y-axis, or Z-axis direction, and a well-known guide rail that supports the chuck table 10 or cutting unit 20 so that it can move in the X-axis, Y-axis, or Z-axis direction. The rotary moving unit 44 includes a well-known motor, etc., that rotates the chuck table 10 around its axis.

[0021] The chuck table 10 is disc-shaped, and its holding surface 11 for holding the wafer 100 is made of porous ceramic or the like. The chuck table 10 is also provided to move freely in the X-axis direction by an X-axis movement unit 41 across the processing area below the cutting unit 20 and the loading / unloading area where the wafer 100 is loaded and unloaded, separated from below the cutting unit 20, and is also provided to rotate freely around an axis parallel to the Z-axis direction by a rotation movement unit 44.

[0022] The chuck table 10 has a holding surface 11 connected to a vacuum suction source (not shown), and the wafer 100 placed on the holding surface 11 is held in place by suction from the vacuum suction source. In the first embodiment, the chuck table 10 holds the back side of the wafer 100 by suction. Multiple clamping parts 12 are provided around the chuck table 10 to clamp the frame unit when holding the frame unit including the wafer 100. The frame unit is, for example, composed of a frame formed in an annular shape with an inner diameter of the opening larger than the outer diameter of the wafer 100, a sheet made of thermoplastic resin or the like, and the wafer 100, with the wafer 100 held in the opening of the frame by the sheet.

[0023] The cutting unit 20 is a processing unit to which a cutting blade 21 for cutting a wafer 100 held by a chuck table 10 is detachably attached. The cutting unit 20 is provided to move in the Y-axis direction by a Y-axis movement unit 42 and is also provided to move in the Z-axis direction by a Z-axis movement unit 43 relative to the wafer 100 held by the chuck table 10. The cutting unit 20 allows the cutting blade 21 to be positioned at any position on the holding surface 11 of the chuck table 10 by the X-axis movement unit 41, the Y-axis movement unit 42 and the Z-axis movement unit 43.

[0024] As shown in Figures 2 and 3, the cutting unit 20 includes a cutting blade 21, a spindle housing 22 that is movable in the Y-axis direction and the Z-axis direction by a Y-axis movement unit 42 and a Z-axis movement unit 43, a spindle 23 that is rotatably mounted on the spindle housing 22 around its axis and to which the cutting blade 21 can be attached at its tip, and a spindle motor (not shown) that rotates the spindle 23 around its axis.

[0025] The cutting blade 21 is a cutting wheel having a substantially ring shape. The cutting blade 21 comprises an annular cutting edge 24 for cutting the wafer 100 and an annular base 25 that supports the cutting edge 24 at its outer edge and is detachably mounted on the spindle 23 (see Figure 6). The cutting edge 24 contains at least abrasive grains such as diamond or CBN (Cubic Boron Nitride) and a binder that binds the abrasive grains, and is formed to a predetermined thickness. In the first embodiment, the blade width of the cutting blade 21 is preferably greater than or equal to the width of the annular region 109 on the wafer 100 where outer peripheral trimming is applied (see Figure 5). The cutting blade 21 may also be a so-called washer blade consisting only of the cutting edge 24, for example.

[0026] The spindle housing 22 is supported so as to be movable in the Z-axis direction by the Z-axis movement unit 43, and is also supported so as to be movable in the Y-axis direction by the Y-axis movement unit 42 via the Z-axis movement unit 43. The spindle housing 22 houses the portion of the spindle 23 excluding the tip and a spindle motor (not shown), and supports the spindle 23 so as to be rotatable around its axis.

[0027] The spindle 23 has a cutting blade 21 mounted at its tip. The spindle 23 is rotated by a spindle motor (not shown), and its tip protrudes from the tip surface of the spindle housing 22. The cutting blade 21 is mounted on the tip of the spindle 23. The axes of the spindle 23 and the cutting blade 21 of the cutting unit 20 are parallel to the Y-axis direction.

[0028] The imaging unit 26 images the workpiece 2 held by the chuck table 10 and acquires the image. The imaging unit 26 is fixed to the cutting unit 20 so as to move integrally with the cutting unit 20. The imaging unit 26 is equipped with multiple image sensors that image the surface 101 of the wafer 100 held by the chuck table 10. The image sensors are, for example, CCD (Charge-Coupled Device) image sensors or CMOS (Complementary MOS) image sensors. The imaging unit 26 images the wafer 100 held on the holding surface 11 of the chuck table 10 and outputs the obtained image to the controller 300.

[0029] Furthermore, the cutting apparatus 1 includes an X-axis position detection unit (not shown) for detecting the X-axis position of the chuck table 10, a Y-axis position detection unit (not shown) for detecting the Y-axis position of the cutting unit 20, a Z-axis position detection unit for detecting the Z-axis position of the cutting unit 20, and an angle detection unit for detecting an angle around the axis of the chuck table 10. The X-axis position detection unit and the Y-axis position detection unit can be configured with a linear scale parallel to the X-axis or Y-axis and a reading head. The Z-axis position detection unit detects the Z-axis position of the cutting unit 20 using motor pulses. The angle detection unit is configured with a well-known rotary encoder or the like.

[0030] The X-axis position detection unit, Y-axis position detection unit, and Z-axis position detection unit output the position of the chuck table 10 in the X-axis direction and the position of the cutting unit 20 in the Y-axis direction or Z-axis direction to the controller 300. The angle detection unit outputs the angle of the chuck table 10 around its axis from a reference position to the controller 300. The positions of each component of the cutting device 1 in the X-axis, Y-axis, and Z-axis directions are determined based on a predetermined reference position (not shown).

[0031] The cutting apparatus 1 also includes a cassette elevator 50 on which a cassette (not shown) for housing wafers 100 before and after cutting is placed and which moves the cassette in the Z-axis direction, a cleaning unit (not shown) for cleaning the wafers 100 after cutting, and a transport unit (not shown) for transporting the workpiece 2 between the cassette, the chuck table 10, and the cleaning unit. The cassette elevator 50 is positioned next to one side in the Y-axis direction of the chuck table 10 located in the loading / unloading area.

[0032] Furthermore, the cutting apparatus 1 includes a processing water supply unit 60 that supplies processing water to the area where the wafer 100 and the cutting blade 21 come into contact. The processing water supply nozzle 61 includes a processing water supply nozzle 61 that supplies processing water to the lower end of the cutting blade 21, and a processing water supply source (not shown) that supplies processing water to the processing water supply nozzle 61.

[0033] The controller 300 controls each component of the cutting device 1 to cause the cutting device 1 to perform machining operations on the wafer 100. More specifically, the controller 300 controls the operation of the chuck table 10, the cutting unit 20, and the moving unit 40. The controller 300 is a computer having a processing unit with a microprocessor such as a CPU (central processing unit), a storage device with memory such as ROM (read-only memory) or RAM (random access memory), and an input / output interface device. The processing unit of the controller 300 performs calculations according to the computer program stored in the storage device and outputs control signals for controlling the cutting device 1 to each component of the cutting device 1 via the input / output interface device.

[0034] The controller 300 includes a correction command unit 310. The correction command unit 310 instructs the cutting unit 20 and the like to perform actions in order to adjust the load applied to the cutting blade 21. The correction command unit 310 includes a bottom position storage unit 311, a correction amount storage unit 312, and a rotation angle storage unit 313. The bottom position storage unit 311 stores the position of the lower end of the cutting blade 21 (bottom position) when the cutting blade 21 is made to cut into the wafer 100. The bottom position storage unit 311 may also store the amount of cutting and the amount left uncut by the cutting blade 21. The correction amount storage unit 312 stores the correction amount when correcting the bottom position of the cutting blade 21. The rotation angle storage unit 313 stores the rotation angle of the chuck table 10 when a recess (e.g., a notch 110) formed in the wafer 100 contacts the lower end of the cutting blade 21 during cutting.

[0035] The controller 300 is connected to a display unit 201, which consists of a liquid crystal display device that displays the status of the machining operation and captured images, an input unit 202 used by the operator to register machining conditions, and a notification unit 203. The input unit 202 consists of at least one of a touch panel provided on the display unit 201 and an external input device such as a keyboard. The notification unit 203 notifies the operator by emitting at least one of sound and light.

[0036] Next, a cutting method using the cutting apparatus 1 configured as described above will be explained. In the first embodiment, a cutting method will be described for cutting an annular region 109 on the surface of a wafer 100 to a predetermined depth and trimming the outer circumference. The cutting method of the first embodiment includes three steps: a holding step, a detection step, and a cutting step. Each of these steps will be described in detail below.

[0037] First, in the holding step, the wafer 100 is held by suction on the holding surface 11 of the chuck table 10. Figure 4 is a diagram illustrating the holding step according to the first embodiment. In the holding step, first, as shown in Figure 4, the wafer 100 is transported above the chuck table 10 with its surface 101 facing upwards using a transport unit (not shown). Then, the back surface 102 of the wafer 100 is held by suction on the holding surface 11 of the chuck table 10 (see Figure 3).

[0038] Next, the wafer 100 and the cutting blade 21 are aligned. Specifically, the X-axis movement unit 41 moves the chuck table 10 to the processing area below the cutting blade 21. Then, the imaging unit 26 photographs the wafer 100 and aligns it to position the cutting blade 21 above the annular region 109 of the wafer 100.

[0039] Next, in the detection step, recesses that overlap the planned cutting line are detected. When trimming the outer circumference of wafer 100 as shown in Figure 1, the annular region 109 corresponds to the planned cutting line, and the notch 110 corresponds to the recess. If recesses other than the notch 110 are formed in the annular region 109, these recesses are also to be detected. In the detection step, the wafer 100 is imaged using the imaging unit 26, and the position of the notch 110 that overlaps the annular region 109 is detected. The detected position of the notch 110 is output to the correction command unit 310 of the controller 300. The position of the notch 110 may be detected using X and Y coordinates, or by the rotation angle of the chuck table 10, or by a combination of both. If recesses other than the notch 110 are formed in the annular region 109, these recesses are also to be detected, and the detected position of the recess is output to the correction command unit 310 of the controller 300. If a rotation angle is output, it is stored in the rotation angle storage unit 313.

[0040] Finally, in the cutting step, with the cutting blade 21 embedded in the annular region 109, the chuck table 10 and the cutting blade 21 are moved relative to each other to cut the annular region 109. Figure 5 is a diagram illustrating the cutting step according to the first embodiment. Figure 6 is a perspective view illustrating the cutting step according to the first embodiment. As shown in Figures 5 and 6, the Z-axis movement unit 43 brings the cutting blade 21 into contact with the annular region 109 on the surface of the wafer 100. Then, the spindle 23 is rotated to rotate the cutting blade 21 around its axis, and the rotational movement unit 44 rotates the chuck table 10 around an axis parallel to the Z-axis direction. In this state, the Z-axis movement unit 43 cuts the cutting blade 21 from the surface 101 side of the wafer 100 to a predetermined thickness, cutting and removing the annular region 109 to the predetermined thickness. The predetermined thickness is set in the bottom position memory unit 311 of the controller 300 prior to the cutting process, and is, for example, about 150 μm.

[0041] As shown in Figure 1, when a recess (notch 110) is formed in the annular region 109 of the wafer 100, the load on the cutting blade 21 differs between the region where the cutting blade 21 contacts the notch 110 and the other regions. That is, the region where the cutting blade 21 contacts the notch 110 has a smaller cutting volume compared to the other regions, resulting in a lower load on the cutting blade 21. Therefore, in the first embodiment, the load on the cutting blade 21 is made different in the cutting step between the region where the cutting blade 21 contacts the notch 110 and the other regions.

[0042] Figure 7 illustrates the cutting step according to the first embodiment. Figure 7 shows the relationship between the shape of the wafer 100 and the cutting depth of the cutting blade 21 (the height of the cutting blade 21 in the Z direction) in the planned cutting line. The load on the cutting blade 21 is reduced while the position of the cutting blade 21 overlaps with the position of the recess (notch 110) detected in the detection step. Therefore, if cutting is continued in the same state as in a position where no recess is formed, the amount of cutting will increase. To this end, the correction command unit 310 of the controller 300 controls the cutting unit 20 while the position of the cutting blade 21 overlaps with the position of the recess (notch 110) detected in the detection step. Specifically, the cutting depth of the cutting blade 21 is reduced to prevent an increase in the amount of cutting in the recess. The correction amount ΔDb is set in the correction amount storage unit 312 of the controller 300 prior to the cutting process, and is, for example, about 2 μm.

[0043] Furthermore, as shown in Figure 7, it is desirable to start correcting the cutting depth of the cutting blade 21 slightly before the detection position of the recess. This is mainly because it takes a predetermined amount of time (so-called rise time / fall time) for the cutting blade 21 to change from its current cutting depth to the corrected cutting depth. It is also desirable to control the cutting so that the correction amount set in the correction amount storage unit 312 is reached at approximately the center position of the recess.

[0044] As described above, according to this embodiment, if a notch 110 (recess) exists on the annular region 109, which is the cutting line, the detection step stores its position (the position of the notch 110 on the cutting line). Then, in the cutting step, the load on the cutting blade 21 is adjusted based on the stored position of the notch 110. More specifically, the cutting depth of the cutting blade 21 is changed so that the load on the cutting blade 21 is reduced at the position where the notch 110 exists. Therefore, when a recess is formed on the cutting line, variations in cutting depth caused by differences in cutting volume can be reduced.

[0045] In the above description, the detection step is performed prior to the cutting step, and the cutting line is cut with the position for changing the cutting depth of the cutting blade 21 predetermined. However, the detection step may also be performed while the cutting step is being executed. That is, the direction of travel of the cutting blade 21 may be monitored by the imaging unit 26 while cutting is being performed, and if a recess is detected in the direction of travel, the cutting depth of the cutting blade 21 may be changed.

[0046] Furthermore, when the detection step is performed while the cutting step is being executed, the method for detecting recesses is not limited to detection based on the image captured by the imaging unit 26. For example, recesses may be detected by monitoring the load current value of the spindle 23 or the cutting load of the cutting blade 21. Multiple detection methods may also be used in combination. For example, if the amount of change in the load current value or the amount of change in the cutting load exceeds a preset threshold, it may be determined that a recess exists in the area where the cutting blade 21 contacts the wafer 100, and the load on the cutting blade 21 may be adjusted. Moreover, the method for reducing the load applied to the cutting blade 21 is not limited to reducing the cutting depth of the cutting blade 21. Alternatively, instead of reducing the load applied to the cutting blade 21, the load on the cutting blade 21 may be increased. For example, methods such as reducing the rotation speed of the spindle 23 or increasing the rotation speed of the chuck table 10 may be used.

[0047] Furthermore, the workpiece 2 is not limited to the wafer 100 shown in Figure 1. For example, it may be a bonded wafer as shown in Figure 8. Figure 8 is a perspective view illustrating another workpiece (bonded wafer) according to the first embodiment. As shown in Figure 8, a bonded wafer 500, which is another example of the workpiece 2, is constructed by stacking the wafer 100 shown in Figure 1 and a carrier wafer 400.

[0048] The carrier wafer 400 is formed in a disc shape with the same diameter as the wafer 100, and its material is not particularly limited; it may be formed from an inorganic material substrate such as glass or ceramics, a semiconductor substrate such as silicon, or a metal substrate such as stainless steel. The bonded wafer 500 is formed by bonding the surface 101 of the wafer 100 to the entire upper surface of the carrier wafer 400 via an adhesive layer. The carrier wafer 400 is a carrier substrate that temporarily holds the wafer 100 during trimming to remove the chamfered portion, or during trimming and subsequent grinding.

[0049] When wafer 100, shown in Figure 1, is used as the workpiece 2, in the cutting step, a so-called half-cut is performed, in which the cutting blade 21 cuts into the annular region 109 of wafer 100 from the surface 101 side to a predetermined thickness. In contrast, when a bonded wafer 500, as shown in Figure 8, is used as the workpiece 2, in the cutting step, the cutting blade 21 cuts into the annular region 109 of wafer 100 from the back surface 102 side to the thickness of wafer 100. That is, in the case of a bonded wafer 500, the cutting blade 21 is made to cut up to the bonding surface between wafer 100 and carrier wafer 400. At this time, if a notch 110 is formed in wafer 100, the area in which the cutting blade 21 contacts the notch 110 has a low load on the cutting blade 21, which can result in a deeper cut, potentially cutting all the way into the carrier wafer 400.

[0050] In contrast, by cutting the bonded wafer 500 using the cutting method of the first embodiment, variations in cutting depth caused by differences in cutting volume can be reduced. Therefore, even if a recess such as a notch 110 is formed on the planned cutting line, it is possible to suppress the carrier wafer 400 from being cut. (Second embodiment)

[0051] In the first embodiment, a cutting method was described in which a wide cutting blade 21 is attached to the cutting unit 20 and the annular region 109 of the wafer 100 is designated as the cutting line, in order to perform so-called edge trimming. In contrast, in the second embodiment, a cutting method was described in which an ultra-thin cutting blade 211 is attached to the cutting unit 20 and the division line 107 of the wafer 100 is designated as the cutting line, in order to perform so-called dicing. The differences from the first embodiment will be described below.

[0052] In the second embodiment, the workpiece 2 may be the wafer 100 shown in Figure 1, or it may be a frame unit including the wafer 100 (a unit configured to be supported by an annular frame via a support member, which is a tape, attached to the back surface 102 side of the wafer 100). In the following description, the wafer 100 will be referred to as the workpiece 2.

[0053] First, in the holding step, the back surface 102 of the wafer 100 is held by suction against the holding surface 11 of the chuck table 10 (see Figures 3 and 4). Next, the wafer 100 and the cutting blade 211 are aligned. Specifically, the chuck table 10 is moved by the X-axis movement unit 41 to the processing area below the cutting blade 211. Then, the wafer 100 is photographed by the imaging unit 26 and aligned to position the cutting blade 211 above the starting point of the planned division line 107 extending in the X-axis direction.

[0054] Next, in the detection step, recesses that overlap the planned cutting line are detected. In the second embodiment, the planned division line 107 corresponds to the planned cutting line, and the notch 110 corresponds to the recess. If recesses other than the notch 110 are formed on the planned division line 107, these recesses are also to be detected. The positions of the detected recesses, such as the notch 110, are output to the correction command unit 310 of the controller 300.

[0055] Next, the cutting step is performed. Figure 9 is a diagram illustrating the cutting step according to the second embodiment. Figure 10 is a perspective view illustrating the cutting step according to the second embodiment. As shown in Figure 9, while rotating the cutting blade 211 around its axis, the cutting unit 20 is moved downward by the Z-axis moving unit 43, causing the cutting blade 211 to cut into the starting point of the division line 107 to a predetermined depth. Subsequently, the chuck table 10 and the cutting unit 20 are moved relative to each other in the X-axis direction, allowing the cutting blade 211 to reach the end point of the division line 107. In this way, a division groove 111 is formed along a single division line 107 extending in the X-axis direction. During the machining of the division groove 111, similar to the first embodiment, the cutting unit 20 is controlled to reduce the load on the cutting blade 211 while the position of the cutting blade 211 coincides with the position of the recess (notch 110) detected in the detection step. This reduces variations in the cutting depth of the division groove 111.

[0056] Once a dividing groove 111 is formed along one dividing line 107, the Y-axis movement unit 42 moves the chuck table 10 and the cutting unit 20 relative to each other in the Y-axis direction, positioning the cutting blade 211 above the starting point of the next dividing line 107 extending in the X-axis direction. Then, the rotating cutting blade 211 is made to cut into the starting point of the dividing line 107, and the chuck table 10 and the cutting unit 20 are moved relative to each other in the X-axis direction to bring the cutting blade 211 to the end point of the dividing line 107. In this way, while adjusting the load on the cutting blade 211, a dividing groove 111 is formed along the next dividing line 107 extending in the X-axis direction (see Figure 9).

[0057] Once the division grooves 111 have been formed along all division lines 107 extending in the X-axis direction, the chuck table 10 is rotated 90°. This leaves multiple undivided division lines 107 extending in the X-axis direction (spaced apart in the Y-axis direction). Using the same procedure as above, cutting is performed along each division line 107 extending in the X-axis direction with the cutting blade 211 to form the division grooves 111.

[0058] At this point, the already formed dividing groove 111 exists as a recess on the dividing line 107. Therefore, after rotating the chuck table 10 by 90°, the cutting step is performed while executing the detection step. That is, when a recess is detected in the area where the cutting blade 211 contacts the wafer 100, the load applied to the cutting blade 211 is reduced, similar to the first embodiment.

[0059] In this way, by performing the cutting method described above, even when cutting the planned division line 107 as the planned cutting line and performing so-called dicing, it is possible to reduce the variation in the cutting depth of the division groove 111. (Third embodiment)

[0060] The third embodiment is a method for manufacturing a semiconductor device chip, wherein some of the steps included in the manufacturing method utilize the cutting method of the first embodiment and the cutting method of the second embodiment described above. The method for manufacturing a semiconductor device chip according to the third embodiment includes three steps: a cutting step, a grinding step, and a splitting step.

[0061] The cutting step is a step in which cutting is performed on an annular region 109 along the outer edge of the wafer 100, which is designated as the cutting line, and is a so-called edge trimming step. The cutting step is performed using the cutting method described in the first embodiment.

[0062] The grinding step involves grinding the back surface 102 of the wafer 100, from which the annular region 109 has been removed by a predetermined thickness in the cutting step, using a grinding device or the like, to thin the wafer 100.

[0063] The splitting step involves cutting the wafer 100, which has been thinned by the grinding step, along the planned splitting line 107 to form a splitting groove 111. The splitting groove 111 is formed using the cutting method described in the second embodiment. Then, the device 108 is split into individual pieces along the splitting groove 111 to obtain a semiconductor device chip. Alternatively, after forming the splitting groove 111, tension may be applied to the wafer 100 (or the sheet bonded to the wafer 100) in the radial expansion direction to expand the width of the splitting groove 111, thereby splitting the device 108 into individual pieces.

[0064] Thus, by using the processing method of the first embodiment and the processing method of the second embodiment at appropriate steps when manufacturing semiconductor device chips, variations in the cutting depth during cutting can be reduced. Therefore, this can contribute to improving the yield of semiconductor device chips.

[0065] While several embodiments of the present invention have been described, these embodiments are provided as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Industrial applicability]

[0066] As described above, the workpiece cutting method of the present invention is useful in the process of cutting a predetermined line using a cutting blade in the manufacturing of semiconductor device chips, and is particularly useful when trimming the edges of wafers that have a chamfered portion formed on their outer edge. It also has the effect of reducing variations in the cutting depth even when a recess is formed on the planned cutting line. [Explanation of symbols]

[0067] 1 Cutting equipment 2 Workpiece 10 Chuck Table 11 Holding surface 12 Clamp section 20 cutting units 21, 211 Cutting Blades 22 Spindle Housing 23 spindles 24 cutting blades 25 Ring base 26 Imaging Unit 40 Mobile Units 41 X-axis movement unit 42 Y-axis movement unit 43 Z-axis movement unit 44 Rotational Movement Unit 50 Cassette Elevators 60 Processing water supply unit 61 Processing water supply nozzle 100 wafers 101 Surface 102 Back side 103 Device Layer 104 circuit board 105 Central area 106 Peripheral surplus area 107 planned division lines 108 devices 109 Circular Region 110 Notches 111 Dividing groove 201 Display Unit 202 Input Unit 203 Hochi Unit 300 controllers 310 Correction Command 311 Bottom position memory section 312 Correction amount storage section 313 Rotation Angle Memory Unit 400 carrier wafers 500 bonded wafers

Claims

1. A method for cutting a workpiece, comprising inserting a cutting blade into the workpiece to a predetermined depth and cutting the workpiece with the cutting blade along a predetermined cutting line set on the workpiece to form a cutting groove of the predetermined depth, A holding step in which the workpiece is held on the holding surface of the chuck table, The cutting step includes moving the chuck table and the cutting blade relative to each other while the cutting blade, which has cutting edges on its outer circumference and is mounted on the tip of a spindle, is inserted into the planned cutting line of the workpiece, thereby cutting the planned cutting line, The workpiece has a recess that overlaps the planned cutting line, A method for cutting a workpiece, wherein the load on the cutting blade is changed in the region corresponding to the recess and in other regions during the cutting step.

2. The system further comprises a detection step for detecting the position of the recess, The cutting step is, The method for cutting a workpiece according to claim 1, characterized in that the load on the cutting blade is changed at the recess position detected in the detection step.

3. The workpiece is a wafer, and the recess is a notch formed on the outer circumference of the wafer indicating the crystal orientation. The planned cutting line is annular along the outer edge of the wafer. The cutting method for a workpiece according to claim 2, wherein the depth of the cutting blade into the wafer is shallower in the region corresponding to the notch than in the other regions.

4. The cutting method for a workpiece according to claim 3, wherein the cutting groove is formed on the wafer while it is bonded to a carrier wafer.

5. The detection step is, The position of the notch is detected from the image captured by the imaging unit. The cutting step is, A method for cutting a workpiece according to claim 3 or claim 4, which is performed after or simultaneously with the detection step.

6. A method for manufacturing semiconductor device chips, A cutting step in which a cutting blade is used to cut a wafer in which a semiconductor device is formed in each region partitioned by multiple intersecting division lines on the surface, a notch is formed on the outer edge, and a cutting line is set along the outer edge of the wafer. A grinding step is performed after the cutting step, The grinding step is followed by a splitting step of splitting the wafer along the planned splitting line to manufacture a semiconductor device chip, and the process is as follows: The notch overlaps the planned cutting line, A method for manufacturing a semiconductor device, comprising changing the load on the cutting blade in the region where the notch is formed and in other regions during the cutting step.

7. A cutting apparatus for cutting the outer edge of a disc-shaped wafer and removing the chamfered portion, A chuck table having a holding surface for holding the wafer and a rotation axis in a direction intersecting the holding surface, A cutting unit comprising a spindle to which a cutting blade having a cutting edge on its outer circumference can be attached, A moving unit that moves the chuck table and the cutting unit relative to each other in a direction intersecting the holding surface, A notch detection mechanism for detecting the position of a notch indicating the crystal orientation formed on the outer edge of the wafer held by the holding surface, A controller comprising memory and a processor, which controls the operation of the chuck table, the cutting unit and the moving unit, The controller is, A cutting apparatus comprising: a notch detection mechanism and a correction command unit that changes the load on the cutting blade in the notch location region and other regions when cutting the wafer.

8. The Correction Command Headquarters, A bottom position storage unit that stores the bottom position of the cutting blade (cutting depth or remaining depth) when the cutting blade is inserted into the outer edge of the wafer, The device includes a correction amount storage unit that stores a correction amount used to correct the bottom surface position of the cutting blade by the moving unit at the notch position detected by the notch detection mechanism, The cutting apparatus according to claim 7, wherein the bottom surface position of the cutting blade at the notch position is corrected by a correction amount stored in the correction amount storage unit.

9. The notch detection mechanism is an imaging unit that images the wafer held on the chuck table, and detects the notch position from the image captured by the imaging unit. The controller is, The cutting apparatus according to claim 7 or claim 8, further comprising a rotation angle storage unit that stores the detected notch position and the rotation angle of the chuck table at the notch position.

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