Cutting method and method of manufacturing chip

Abstract

To provide a novel cutting method by which a workpiece can be cut along a predetermined cutting plane.SOLUTION: A cutting method for cutting a workpiece including a crystal structure having a c axis which is inclined with respect to a perpendicular of a surface and a c face which is vertical to the c axis includes: a holding step of holding the workpiece; and a cutting step of cutting in the workpiece by a tip of an annular cutting edge by rotating a cutting blade comprising the cutting edge, thereby cutting the workpiece along a predetermined cutting plane which is vertical to the surface and inclined with respect to the c face. In the cutting step, the workpiece is cut in by the tip in a state where a force in a direction in which an angle which is formed by the predetermined cutting plane and the tip when the workpiece is cut in by the tip is made close to 0° acts from the workpiece onto the cutting edge.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a cutting method for cutting a workpiece containing a crystalline structure. [Background technology]

[0002] Chips (device chips) equipped with power devices suitable for controlling electric power are incorporated into power electronics equipment such as inverters. In recent years, many of these power devices have been manufactured using silicon carbide (SiC) wafers containing single crystals of SiC, which are advantageous for achieving high voltage resistance and low loss (see, for example, Patent Document 1).

[0003] The crystal structure of SiC is a hexagonal system with six-fold symmetry, and has a c-axis as a six-fold rotation axis and a c-plane perpendicular to this c-axis. In SiC wafers, due to the manufacturing method of these SiC wafers, the c-axis is generally tilted with respect to the normal to the surface of the SiC wafer, which is the surface on which power devices and the like will be formed.

[0004] When dividing a SiC wafer into multiple chips, for example, a cutting device is used, which has a processing tool called a cutting blade with an annular cutting edge attached to a spindle. The cutting blade is rotated at high speed and cuts along a cutting plane (cutting line, street) set perpendicular to the surface of the SiC wafer, cutting the SiC wafer along the cutting plane and dividing it into multiple chips. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-140341 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a cutting blade cuts into a workpiece that mainly contains a material such as SiC with a trigonal or hexagonal crystal structure, the workpiece may be cut along a plane that is tilted from the intended cutting plane, making it impossible to obtain a chip with the desired shape.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a new cutting method that is capable of cutting a workpiece along a plane to be cut. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a cutting method for cutting a workpiece having a crystal structure with a c-axis tilted relative to a normal to the surface and a c-plane perpendicular to the c-axis, the method comprising: a holding step for holding the workpiece; and a cutting step for rotating a cutting blade having an annular cutting edge to cut the workpiece with the tip of the cutting edge into the workpiece, thereby cutting the workpiece along a planned cutting plane that is perpendicular to the surface and tilted relative to the c-plane, wherein in the cutting step, a force is applied from the workpiece to the cutting edge in a direction that causes the angle between the planned cutting plane and the tip to approach 0° when the tip is cut into the workpiece.

[0009] In one aspect of the present invention, the cutting blade is configured so that the tip end is not inclined relative to the base end of the cutting blade opposite the tip end when the cutting edge is stationary without cutting into the workpiece, and the cutting step may involve cutting the tip end into the workpiece with the base end inclined from the intended cutting plane. In this case, in the cutting step, it is preferable that the base end is inclined from the intended cutting plane so that the base end forms an angle with respect to the intended cutting plane that is greater than 0° and smaller than the angle between the perpendicular line and the c-axis.

[0010] In one aspect of the present invention, the cutting blade may be configured such that the tip end is inclined relative to the base end opposite the tip end of the cutting blade when the cutting blade is stationary and not cutting into the workpiece. In this case, the cutting blade is preferably configured such that the tip end forms an angle with the base end that is greater than 0° and smaller than the angle between the perpendicular and the c-axis when the cutting blade is stationary and not cutting into the workpiece.

[0011] In one aspect of the present invention, the cutting blade is configured so that when the cutting edge is stationary without cutting into the workpiece, the tip does not tilt relative to the base end opposite the tip of the cutting edge, and when the cutting edge is rotated without cutting into the workpiece, the tip tilts relative to the base end due to the force generated by the rotation of the cutting edge, and during the cutting process, the tip may be caused to cut into the workpiece in a state adjusted so that at least a portion of the force acting on the cutting edge from the workpiece and the force generated by the rotation of the cutting edge cancel each other out. [Effects of the Invention]

[0012] In a cutting method according to one aspect of the present invention, the tip is caused to cut into the workpiece in a state in which a force acts from the workpiece on the cutting edge in a direction that causes the angle between the tip and the planned cutting plane to approach 0° when the tip is caused to cut into the workpiece. Thus, according to the cutting method according to one aspect of the present invention, even if the workpiece includes a crystal structure having a c-axis that is tilted with respect to the normal to the surface, it is possible to cut the workpiece along the planned cutting plane that is perpendicular to the surface. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing a cutting device. [Figure 2] FIG. 2 is a perspective view showing the workpiece. [Figure 3] FIG. 3 is a side view showing the workpiece. [Figure 4] FIG. 4 is a cross-sectional view showing how the workpiece is cut. [Figure 5] FIG. 5 is a cross-sectional view showing how the workpiece is cut along a plane inclined from the intended cutting plane. [Figure 6] FIG. 6 is a cross-sectional view showing how a workpiece is cut in the cutting method according to this embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing how a workpiece is cut in the cutting method according to the first modified example. [Figure 8] FIG. 8 is a front view showing the state in which a cutting blade used in a cutting method according to a second modified example is rotated. [Figure 9] FIG. 9 is a cross-sectional view showing how a workpiece is cut in the cutting method according to the second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a perspective view showing a cutting device 2 used in a cutting method according to this embodiment. In Fig. 1, some components of the cutting device 2 are expressed as functional blocks. In addition, the X-axis, Y-axis, and Z-axis used in the following description are perpendicular to one another.

[0015] As shown in Fig. 1, the cutting device 2 includes a base 4 that supports various components. An opening 4a is formed in a corner of the top surface of the base 4, and a cassette table 6 that is raised and lowered by a lifting mechanism (not shown) is disposed within this opening 4a. A cassette 8 that can accommodate a plate-shaped workpiece 11 is placed on the top surface of the cassette table 6. For ease of explanation, only the outline of the cassette 8 is shown in Fig. 1.

[0016] Fig. 2 is a perspective view showing a workpiece 11 to be cut by the cutting method according to this embodiment, and Fig. 3 is a side view showing the workpiece 11. The workpiece 11 is a disk-shaped semiconductor wafer (SiC wafer) mainly containing single crystals of SiC (silicon carbide) having a hexagonal crystal structure, and is typically obtained by slicing a semiconductor ingot (SiC ingot) produced by a sublimation recrystallization method.

[0017] 2 and 3, the workpiece 11 has a first surface 11a that is generally flat and circular, and a second surface 11b that is generally flat and circular and located opposite the first surface 11a and generally parallel to the first surface 11a. The first surface 11a and the second surface 11b are connected to each other by a side surface 11c. A generally flat first orientation flat 11d and a generally flat second orientation flat 11e that is generally perpendicular to the first orientation flat 11d are formed on a portion of the side surface 11c.

[0018] The first orientation flat 11d and the second orientation flat 11e are aligned with the crystal orientation of SiC constituting the workpiece 11, and are both linear when viewed from a direction perpendicular to the first surface 11a and the second surface 11b. The length of the first orientation flat 11d when viewed from a direction perpendicular to the first surface 11a and the second surface 11b is longer than the length of the second orientation flat 11e when viewed from the same direction.

[0019] Generally, in the process of growing a SiC crystal to manufacture the workpiece 11, the c-axis 11f of the SiC single crystal constituting the workpiece 11 is tilted with respect to the perpendicular 11g to the first surface 11a and the second surface 11b. Specifically, the c-axis 11f is tilted at an angle α (also called an off-angle) from the perpendicular 11g toward the second orientation flat 11e. Therefore, the c-plane 11h perpendicular to the c-axis 11f also forms an angle α with respect to the first surface 11a and the second surface 11b.

[0020] The c-plane 11h is a crystal plane or lattice plane in a hexagonal (or trigonal) crystal structure, and is expressed as {0001} using Miller indices. When the workpiece 11 is a semiconductor wafer mainly containing single crystal SiC, α is typically 4°. However, α in this case can be freely set within the range of 1° to 6°.

[0021] The first surface 11a side of the workpiece 11 is partitioned into a plurality of small areas by cutting planes (cutting lines, streets) 13a and 13b perpendicular to the first surface 11a, and devices 15 such as power devices are formed in each small area. When the workpiece 11 configured in this manner is stored in the cassette 8, for example, as shown in Fig. 1, tape 17 is attached to the second surface 11b side of the workpiece 11, and an annular frame 19 is fixed to the outer edge of the tape 17.

[0022] In this embodiment, a semiconductor wafer primarily containing SiC single crystals is used as the workpiece 11, but the workpiece 11 may be made of other materials having a trigonal or hexagonal crystal structure. A typical example of a trigonal material is lithium tantalate (LT), and another example of a hexagonal material is gallium nitride (GaN). When the workpiece 11 primarily contains LT single crystals, α is, for example, 9°, and when the workpiece 11 primarily contains GaN single crystals, α is, for example, 0.5°.

[0023] Furthermore, the first orientation flat 11d and the second orientation flat 11e do not necessarily have to be formed on the side surface 11c of the workpiece 11. Furthermore, instead of or in addition to the first orientation flat 11d and the second orientation flat 11e, another orientation flat or notch (cutout) or the like according to the crystal orientation may be provided on the workpiece 11.

[0024] The type, number, shape, structure, size, arrangement, etc. of the device 15 are not limited to the above-mentioned embodiment. The device 15 does not have to be formed on the workpiece 11. Furthermore, the tape 17 does not necessarily have to be attached to the workpiece 11. In other words, the workpiece 11 does not necessarily have to be supported by the annular frame 19 via the tape 17.

[0025] 1, an opening 4b that is long in the direction along the X-axis is formed at a position adjacent to cassette table 6 along the Y-axis. A ball screw type chuck table moving mechanism (processing feed mechanism) 10 is disposed within opening 4b. Chuck table moving mechanism 10 includes a rotational drive source (not shown) such as a motor connected to the end of a ball screw, and an X-axis moving table (not shown) having a nut portion coupled to the ball screw, and moves the X-axis moving table along the X-axis.

[0026] The top of the X-axis moving table is covered by a table cover 10a. In addition, accordion-shaped dustproof and drip-proof covers 10b that expand and contract in accordance with the movement of the X-axis moving table and table cover 10a are attached to both ends of the table cover 10a in the direction along the X-axis. A chuck table (holding table) 12 for holding a workpiece 11 is arranged above the X-axis moving table in a manner that it is exposed from the table cover 10a.

[0027] The chuck table 12 is connected to a rotary drive source (not shown), such as a motor, fixed to the X-axis moving table, and rotates around a rotation axis that is roughly parallel to the Z-axis. The chuck table 12 is moved along the X-axis together with the X-axis moving table by the chuck table moving mechanism 10 described above (processing feed).

[0028] The chuck table 12 includes a disk-shaped frame 14 made of a metal such as stainless steel. A recess 14a (see FIG. 4) with a circular opening at the top end is formed on the top surface of the frame 14. A disk-shaped holding plate 16 that matches the shape of the recess 14a is fitted into the recess 14a of the frame 14. Four clamps 18 are arranged around the periphery of the frame 14 to secure an annular frame 19 that supports the workpiece 11.

[0029] The holding plate 16 is made of a porous plate-like material such as ceramics, and its upper surface (holding surface) 16a holds the workpiece 11. The upper surface 16a of the holding plate 16 is configured to be generally parallel to the X-axis and Y-axis when the holding plate 16 is fitted into the recess 14a. In other words, the chuck table 12 rotates around a rotation axis that is generally perpendicular to the upper surface 16a of the holding plate 16.

[0030] A suction source (not shown) is connected to the bottom of the recess 14a of the frame 14 via a flow path 14b, a valve (not shown), etc. Therefore, when the valve is opened, negative pressure from the suction source acts on the upper surface 16a of the holding plate 16 through the flow path 14b, etc. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, other pumps operating on different principles may also be used as the suction source.

[0031] Above the opening 4b, one or more transport mechanisms (not shown) are arranged that can transport the above-mentioned workpiece 11 (frame 19) to the chuck table 12, etc. The workpiece 11 transported by the transport mechanism is placed on the upper surface 16a of the chuck table 12 so that the first surface 11a side is exposed upward, for example.

[0032] A cantilevered support structure 20 is provided at a position adjacent to the opening 4b along the Y axis. A cutting unit movement mechanism (indexing feed mechanism, cutting feed mechanism) 22 is disposed on top of the support structure 20. This cutting unit movement mechanism 22 has a pair of Y-axis guide rails 24 that are fixed to the front (surface) of the support structure 20 and are generally parallel to the Y axis.

[0033] A Y-axis moving plate 26 that constitutes the cutting unit moving mechanism 22 is attached to the Y-axis guide rail 24 in a manner that allows it to slide along the Y-axis. A nut portion (not shown) that constitutes a ball screw is provided on the rear side (back surface side) of the Y-axis moving plate 26, and a screw shaft 28 that is generally parallel to the Y-axis guide rail 24 is rotatably connected to the nut portion.

[0034] A rotary drive source (not shown), such as a motor, is connected to one end of the screw shaft 28. By rotating the screw shaft 28 with the rotary drive source, the Y-axis moving plate 26 moves along the Y-axis guide rail 24. A pair of Z-axis guide rails 30, which are generally parallel to the Z-axis, are fixed to the front (surface) of the Y-axis moving plate 26. A Z-axis moving plate 32 is attached to the pair of Z-axis guide rails 30 in a manner that allows it to slide along the Z-axis.

[0035] A nut portion (not shown) constituting a ball screw is provided on the rear side (back surface side) of Z-axis moving plate 32, and a screw shaft 34 that is generally parallel to Z-axis guide rail 30 is rotatably connected to the nut portion. A rotation drive source 36 such as a motor is connected to one end of screw shaft 34. By rotating screw shaft 34 with rotation drive source 36, Z-axis moving plate 32 moves along Z-axis guide rail 30.

[0036] A cutting unit 38 is provided below the Z-axis moving plate 32. The cutting unit 38 has a cylindrical spindle housing 40. Inside the spindle housing 40, a cylindrical spindle 42 (see FIG. 4, etc.) except for its tip is housed, which serves as a rotation axis parallel to or slightly tilted from the Y-axis.

[0037] A disk-shaped cutting blade 44 is attached to the tip of the spindle 42, which is exposed to the outside of the spindle housing 40. A rotational drive source (not shown), such as a motor, is connected to the base end of the spindle 42. The cutting blade 44 is a so-called hub-type cutting blade that integrally includes a disk-shaped blade base 46 (see FIG. 4, etc.) made of metal or the like, and an annular cutting edge 48 (see FIG. 4, etc.) provided along the outer periphery of the blade base 46. The cutting edge 48 is obtained by fixing abrasive grains, such as diamond, with a binder, such as resin.

[0038] A camera (imaging unit) 50 for capturing images of the workpiece 11 held by the chuck table 12 is fixed to a position adjacent to the cutting unit 38 below the Z-axis moving plate 32. Therefore, when the Y-axis moving plate 26 is moved along the Y-axis by the cutting unit moving mechanism 22, the cutting unit 38 and camera 50 also move along the Y-axis (indexing feed). Also, when the Z-axis moving plate 32 is moved along the Z-axis by the cutting unit moving mechanism 22, the cutting unit 38 and camera 50 also move along the Z-axis (cutting feed).

[0039] An opening 4c is formed at a position opposite to opening 4a with respect to opening 4b. A cleaning unit 52 for cleaning the workpiece 11 and the like after cutting is disposed within opening 4c. A controller (control unit) 54 is connected to elements such as the chuck table moving mechanism 10, the transport mechanism, the cutting unit moving mechanism 22, the cutting unit 38, the camera 50, and the cleaning unit 52.

[0040] The controller 54 is configured by, for example, a computer including a processing device 56 and a storage device 58, and controls the operation of each element of the above-mentioned cutting device 2 so as to properly cut the workpiece 11. The processing device 56 is typically a CPU (Central Processing Unit) and performs various processes required to control the above-mentioned elements.

[0041] The storage device 58 includes, for example, a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a hard disk drive, a flash memory, etc. The functions of the controller 54 are realized, for example, by the processing device 56 operating in accordance with software (programs, etc.) stored in the storage device 58.

[0042] An input / output device (input device, output device) 60 that serves as a user interface is connected to this controller 54. The input / output device 60 is, for example, a touch screen, and inputs commands from an operator to the controller 54. Furthermore, the input / output device 60 outputs (displays in the case of a touch screen) information about the cutting device 2 based on commands from the controller 54 in a format that can be recognized by the operator.

[0043] In this embodiment, the input / output device 60 has both an input function and an output function, but an input device having an input function and an output device having an output function may each be connected to the controller 54. Examples of input devices that can be used include a keyboard and a mouse. Examples of output devices that can be used include a display device such as a liquid crystal display, a speaker that can communicate information by sound, and an indicator light that can communicate information by the color of light or the state of light emission (on, blinking, off, etc.).

[0044] FIG. 4 is a cross-sectional view showing how the workpiece 11 is cut. For ease of explanation, hatching and the like of the workpiece 11 are omitted in FIG. 4. In the cutting method according to this embodiment, first, the workpiece 11 is held by the chuck table 12 (holding step). Specifically, the workpiece 11 is carried out of the cassette 8 by a transport mechanism or the like of the cutting device 2 and placed on the chuck table 12. In this embodiment, the workpiece 11 is placed on the chuck table 12 so that the second surface 11b faces the upper surface 16a of the chuck table 12.

[0045] Next, the valve is opened to apply negative pressure from the suction source to the upper surface 16a of the chuck table 12. As a result, the second surface 11b side of the workpiece 11 (the tape 17 in this embodiment) is sucked by the upper surface 16a of the chuck table 12, and the workpiece 11 is held by the chuck table 12 with the first surface 11a facing upward. Note that the frame 19 is fixed by a clamp 18, as shown in FIG.

[0046] After the workpiece 11 is held by the chuck table 12, the cutting blade 44 is rotated to cut a part of the cutting edge 48 into the workpiece 11, thereby cutting the workpiece 11 (cutting step). Specifically, a rotation drive source connected to the chuck table 12 adjusts the orientation of the chuck table 12 around the Z axis so that the intended cutting planes 13a, 13b, etc., which are to be cut, are approximately parallel to the X axis.

[0047] Furthermore, the chuck table moving mechanism 10 adjusts the position of the chuck table 12 along the X-axis so that, when viewed from above, at least a portion including the lowest point of the cutting edge 48 of the cutting blade 44 does not overlap the workpiece 11. Furthermore, the cutting unit moving mechanism 22 adjusts the position of the cutting unit 38 along the Y-axis so that at least a portion of the cutting edge 48 of the cutting blade 44 is positioned within a plane including the target intended cutting planes 13a, 13b, etc.

[0048] Thereafter, the cutting unit moving mechanism 22 adjusts the position of the cutting unit 38 along the Z axis so that the height (position along the Z axis) of the lowest point of the cutting edge 48 of the cutting blade 44 is slightly lower than the second surface 11b of the workpiece 11. In addition, the rotation drive source of the cutting unit 38 rotates the cutting blade 44 together with the spindle 42 at a rotation speed (rotational frequency) of about 10,000 rpm to 50,000 rpm.

[0049] Then, the chuck table moving mechanism 10 moves the chuck table 12 at a speed (processing feed rate) of about 20 mm / s to 200 mm / s so that the cutting blade 44 traverses the workpiece 11 along the X-axis. At the same time, a cutting liquid, typically pure water, is supplied to the workpiece 11 and the cutting blade 44. As a result, the workpiece 11 is cut and sliced ​​by the cutting blade 44 along the target planned cutting planes 13a, 13b, etc.

[0050] However, when attempting to cut the above-described workpiece 11 along the cutting plane 13a inclined relative to the c-face 11h (the cutting plane 13a not perpendicular to the c-face 11h), the workpiece 11 may end up being cut along a plane inclined relative to the cutting plane 13a. Figure 5 is a cross-sectional view showing how the workpiece 11 is cut along a plane inclined relative to the cutting plane 13a. Note that hatching and the like of the workpiece 11 have been omitted in Figure 5 for ease of explanation.

[0051] 5, the base end 48a (portion close to the blade base 46) of the cutting edge 48 of the cutting blade 44 is parallel to the intended cutting plane 13a, and the tip end 48b (portion farther from the blade base 46) of the cutting edge 48 located on the opposite side of the base end 48a cuts into the workpiece 11. In other words, the tip end 48b of the cutting edge 48 cuts into the workpiece 11 so that the direction along the side surface 48c of the base end 48a of the cutting edge 48 (the direction in which the base end 48a extends) is parallel to the intended cutting plane 13a.

[0052] 5, the cutting edge 48 may be deformed so that the tip end 48b forms a predetermined angle with respect to the base end 48a, and the workpiece 11 may be cut along a surface that is inclined from the intended cutting plane 13a. Specifically, the cutting edge 48 may be deformed so that the side surface 48d of the tip end 48b forms an angle of about 0.5° to 1.0° with respect to the side surface 48c of the base end 48a (when α is 4°).

[0053] After extensive research into this phenomenon, the inventor discovered that when the cutting edge 48 of the cutting blade 44 is inserted into the workpiece 11 in a direction inclined relative to the c-face 11h, a force F1 in a direction along the c-face 11h acts from the workpiece 11 on the cutting edge 48, deforming the cutting edge 48. Based on this discovery, the inventor also considered that if a force F1 could be applied from the workpiece 11 to the cutting edge 48, which would deform the cutting edge 48 in a direction such that the angle between the intended cutting plane 13a and the tip 48b approaches 0°, the workpiece 11 could be cut along the intended cutting plane 13a.

[0054] That is, if a force F1 acts from the workpiece 11 on the cutting edge 48 in a direction that brings the angle between the intended cutting plane 13a and the tip 48b closer to 0°, it becomes possible to cut the workpiece 11 along the intended cutting plane 13a. The present inventors have completed the present inventions based on these findings.

[0055] Fig. 6 is a cross-sectional view showing how the workpiece 11 is cut in the cutting method of this embodiment. For ease of explanation, hatching and the like of the workpiece 11 are omitted in Fig. 6. Fig. 6 also shows a cross section that is parallel to the YZ plane and passes through the lowest point and center of rotation (not shown) of the cutting edge 48 (cutting blade 44).

[0056] 6, in this embodiment, a cutting blade 44 is used in which the tip end 48b is not substantially inclined with respect to the base end 48a located between the blade base 46 and the tip end 48b when the cutting edge 48 is stationary and not cutting into the workpiece 11. In other words, the side surface 48c of the base end 48a and the side surface 48d of the tip end 48b are generally parallel when not cutting into the workpiece 11.

[0057] 6, in this embodiment, the tip end 48b cuts into the workpiece 11 with the base end 48a (side surface 48c) tilted from the planned cutting plane 13a. β, which is the angle formed between the base end 48a (side surface 48c) and the planned cutting plane 13a, is typically greater than 0° and smaller than α (the angle between the perpendicular line 11g and the c-axis 11f), and is preferably about 0.4° to 1.0° when α is 4°, for example.

[0058] As a result, a force F1 in the direction shown in Fig. 6 (a force F1 in the direction that brings the angle between the plane to be cut 13a and the tip end 48b closer to 0°) acts on the cutting edge 48, and the cutting edge 48 is deformed as shown by the solid line in Fig. 6. As a result, in the cross section shown in Fig. 6, the angle between the plane to be cut 13a and the tip end 48b (side surface 48d) becomes sufficiently small, and the workpiece 11 is cut along the plane to be cut 13a.

[0059] In this embodiment, the spindle 42 is tilted in the YZ plane with respect to the Y axis to tilt the base end 48a (side surface 48c) from the intended cutting plane 13a. Specifically, the cutting unit 38 is tilted with respect to the Z-axis moving plate 32 so that the center line of the spindle 42 forms an angle β with respect to the Y axis in the YZ plane. To easily adjust the tilt of the cutting unit 38 with respect to the Z-axis moving plate 32, the cutting device 2 preferably includes a tilt adjustment mechanism.

[0060] As the cutting edge 48 is deformed as described above, the position of the tip 48b relative to the workpiece 11 is displaced along the Y-axis, so it is desirable to have the cutting edge 48 cut into the workpiece 11 at a position that takes this displacement into consideration. In other words, it is desirable to adjust the position of the cutting blade 44 relative to the chuck table 12 in consideration of the displacement that occurs due to the deformation of the cutting edge 48. For example, when α is 4°, the displacement that occurs due to the deformation of the cutting edge 48 is approximately 3 μm to 20 μm along the Y-axis.

[0061] Incidentally, immediately after the cutting edge 48 cuts into the workpiece 11, the cutting edge 48 may not be sufficiently deformed by the force F1, and may not be able to cut the workpiece 11 along the intended cutting plane 13a. On the other hand, when the workpiece 11 is cut under the conditions described above, the cutting edge 48 is sufficiently deformed when it reaches a region about 3 mm inward from the outer periphery of the workpiece 11, and is able to cut the workpiece 11 along the intended cutting plane 13a.

[0062] Therefore, when cutting workpiece 11 using the cutting method of this embodiment to manufacture chips including devices 15, it is desirable to use an inner region at least 3 mm away from the outer periphery of workpiece 11 as the device region where devices 15 are formed. This makes it possible to more reliably achieve the shape required for chips including devices 15.

[0063] As described above, in the cutting method according to this embodiment, the tip 48b is caused to cut into the workpiece 11 in a state in which a force F1 acts from the workpiece 11 on the cutting blade 48 in a direction that causes the angle between the planned cutting plane 13a and the tip 48b to approach 0° when the tip 48b is caused to cut into the workpiece 11. Therefore, even if the workpiece 11 includes a hexagonal (or trigonal) crystal structure having a c-axis 11f tilted with respect to the normal 11g of the first surface 11a, it is possible to cut the workpiece 11 along the planned cutting plane 13a that is perpendicular to the first surface 11a.

[0064] The present invention is not limited to the above-described embodiment and can be practiced with various modifications. For example, in the above-described embodiment, the cutting blade 44 is used in which the tip end 48b is not substantially inclined relative to the base end 48a when the cutting edge 48 is stationary and not cutting into the workpiece 11. However, the cutting blade 44 may be configured so that the tip end 48b is inclined relative to the base end 48a.

[0065] Fig. 7 is a cross-sectional view showing how the workpiece 11 is cut in the cutting method according to the first modified example. For ease of explanation, hatching and the like of the workpiece 11 are omitted in Fig. 7. Fig. 7 also shows a cross section that is parallel to the YZ plane and passes through the lowest point and center of rotation (not shown) of the cutting edge 48 (cutting blade 44).

[0066] 7, in this modification, a cutting blade 44 is used in which the tip end 48b is inclined with respect to the base end 48a located between the blade base 46 and the tip end 48b when the cutting edge 48 is stationary and not cutting into the workpiece 11. In other words, the side surface 48c of the base end 48a and the side surface 48d of the tip end 48b are inclined when not cutting into the workpiece 11.

[0067] The angle γ formed between the base end 48a (side surface 48c) and the tip end 48b (side surface 48d) is typically greater than 0° and smaller than α (the angle between the perpendicular line 11g and the c-axis 11f), and is preferably about 0.4° to 1.0° when α is 4°. In this modification, as shown in FIG. 7, the tip end 48b cuts into the workpiece 11 without tilting the base end 48a (side surface 48c) from the plane to be cut 13a.

[0068] As a result, a force F1 in the direction shown in Fig. 7 (a force F1 in the direction that brings the angle between the intended cutting plane 13a and the tip 48b closer to 0°) acts on the cutting edge 48, and the cutting edge 48 is deformed as shown by the solid line in Fig. 7. As a result, in the cross section shown in Fig. 7, the angle between the intended cutting plane 13a and the tip 48b (side surface 48d) becomes sufficiently small, and the workpiece 11 is cut along the intended cutting plane 13a. Other details are the same as those of the above-mentioned embodiment.

[0069] In the cutting method according to this modified example, the tip 48b is caused to cut into the workpiece 11 in a state in which a force F1 acts from the workpiece 11 on the cutting edge 48 in a direction that causes the angle between the planned cutting plane 13a and the tip 48b to approach 0° when the tip 48b is caused to cut into the workpiece 11. Therefore, even if the workpiece 11 includes a hexagonal (or trigonal) crystal structure having a c-axis 11f tilted with respect to the normal 11g of the first surface 11a, it is possible to cut the workpiece 11 along the planned cutting plane 13a that is perpendicular to the first surface 11a.

[0070] In this modification, the tip end 48b cuts into the workpiece 11 with the base end 48a not tilted from the intended cutting plane 13a, but the base end 48a may be tilted from the intended cutting plane 13a. That is, the cutting blade 44 according to this modification, in which the tip end 48b is tilted with respect to the base end 48a, and the method according to the embodiment in which the spindle 42 is tilted with respect to the Y-axis may be appropriately combined.

[0071] Fig. 8 is a front view showing the rotation of a cutting blade 44 used in a cutting method according to the second modified example, and Fig. 9 is a cross-sectional view showing the cutting of a workpiece 11 in the cutting method according to the second modified example. For ease of explanation, hatching and the like of the workpiece 11 are omitted in Fig. 9. Fig. 9 also shows a cross section parallel to the YZ plane and passing through the lowest point of the cutting edge 48 (cutting blade 44) and the center of rotation (not shown).

[0072] In this second modified example, as shown in Fig. 8, a cutting blade 44 is used that is configured so that when the cutting edge 48 is rotated without cutting into the workpiece 11, the cutting edge 48 is deformed by a force F2 that is generated by this rotation. Specifically, the cutting blade 44 used in the second modified example is configured so that the tip end 48b is not substantially inclined relative to the base end 48a when the cutting edge 48 is stationary (not rotating) without cutting into the workpiece 11, as shown by the solid line in Fig. 8.

[0073] 8, the cutting blade 44 used in the second modified example is configured so that the tip end 48b of the cutting blade 48 is tilted relative to the base end 48a of the cutting blade 48 due to a force F2 generated by the rotation of the cutting blade 48 (cutting blade 44) when the cutting blade 48 is rotated without cutting into the workpiece 11. Note that one possible cause of deformation of the cutting blade 48 due to the rotation of the cutting blade 48 (cutting blade 44) is asymmetric expansion (deformation) of the blade base 46 due to centrifugal force.

[0074] 9, in this second modified example, the tip portion 48b cuts into the workpiece 11 in a state adjusted so that part or all of the force F1 acting on the cutting blade 48 from the workpiece 11 and the force F2 generated by rotation are oriented to cancel each other out. More specifically, the orientation of the workpiece 11 (chuck table 12) relative to the cutting blade 44 (spindle 42) is adjusted so that part or all of the force F1 and the force F2 are oriented to cancel each other out.

[0075] As a result, as shown by the dashed line in Fig. 9, the tip end 48b, which has been deformed so as to be inclined relative to the base end 48a due to the force F2 generated by the rotation, is deformed in the opposite direction by the force F1, as shown by the solid line in Fig. 9. Then, the angle formed between the intended cutting plane 13a and the tip end 48b approaches 0°.

[0076] In other words, part or all of the force F1 and the force F2 cancel each other out, and the angle between the cutting plane 13a and the tip 48b (side surface 48d) becomes sufficiently small. As a result, the workpiece 11 is cut along the cutting plane 13a. Other details are the same as those of the above-described embodiment.

[0077] In the cutting method according to this modified example, the tip 48b is caused to cut into the workpiece 11 in a state in which a force F1 acts from the workpiece 11 on the cutting edge 48 in a direction that causes the angle between the planned cutting plane 13a and the tip 48b to approach 0° when the tip 48b is caused to cut into the workpiece 11. Therefore, even if the workpiece 11 includes a hexagonal (or trigonal) crystal structure having a c-axis 11f tilted with respect to the normal 11g of the first surface 11a, it is possible to cut the workpiece 11 along the planned cutting plane 13a that is perpendicular to the first surface 11a.

[0078] Incidentally, the force F2 utilized in the second modification may also occur in the cutting method according to the above-described embodiment or modification 1. In that case, it is desirable to adjust β, which is the angle of the spindle 42 with respect to the Y axis, or γ, which is the angle between the base end 48a and the tip end 48b, in consideration of the force F2, also in the cutting method according to the embodiment or modification 1.

[0079] In the above-described embodiment and each modified example, the workpiece 11 is cut by causing the cutting blade 48 to cut into the workpiece 11 so that the height of the lowest point of the cutting blade 48 is lower than the second surface 11b of the workpiece 11, but the cutting method of the present invention can also be applied to cases where the workpiece 11 is not cut. For example, a groove may be formed in the workpiece 11 by causing the cutting blade 48 to cut into the workpiece 11 so that the height of the lowest point of the cutting blade 48 is higher than the second surface 11b of the workpiece 11.

[0080] In addition, the structures, methods, etc. according to the above-described embodiments and modifications may be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0081] 11: Workpiece 11a: 1st surface 11b: 2nd surface 11c: Side surface 11d: First Orientation Flat 11e: 2nd Orientation Flat 11f:c axis 11g: Perpendicular 11h:c side 13a: Planned cutting plane (planned cutting line, street) 13b: Planned cutting plane (planned cutting line, street) 15: Device 17: Tape 19: Frame 2:Cutting device 4: Base 4a: Opening 4b: Opening 4c: opening 6: Cassette table 8: Cassette 10: Chuck table moving mechanism (processing feed mechanism) 10a: Table cover 10b: Dustproof and water-resistant cover 12: Chuck table (holding table) 14:Frame body 14a: recess 14b: Flow path 16: Holding plate 16a:Top surface (holding surface) 18: Clamp 20:Support structure 22: Cutting unit movement mechanism (indexing feed mechanism, cutting feed mechanism) 24: Y-axis guide rail 26: Y-axis moving plate 28: Screw shaft 30: Z-axis guide rail 32: Z-axis moving plate 34: Screw shaft 36: Rotation drive source 38: Cutting unit 40: Spindle housing 42: Spindle 44: Cutting blade 46: Blade base 48: Cutting edge 48a: Proximal end 48b: Tip 48c: Side surface 48d: Side surface 50: Camera (imaging unit) 52: Cleaning unit 54: Controller (control unit) 56: Processing equipment 58:Storage device 60: Input / output device (input device, output device)

Claims

1. A cutting method for cutting a workpiece including a crystal structure having a c-axis tilted with respect to a normal to the surface and a c-plane perpendicular to the c-axis, comprising: a holding step of holding the workpiece; a cutting step of rotating a cutting blade having an annular cutting edge to cut a tip of the cutting edge into the workpiece so as to cut the workpiece along a planned cutting plane that is perpendicular to the surface and inclined with respect to the c-plane, In the cutting step, the tip portion is caused to cut into the workpiece in a state in which a force acts from the workpiece on the cutting blade in a direction that causes the angle between the intended cutting plane and the tip portion to approach 0° when the tip portion is caused to cut into the workpiece.

2. The cutting blade is configured so that the tip end portion of the cutting blade is not inclined relative to the base end portion opposite to the tip end portion of the cutting blade when the cutting blade is stationary without cutting into the workpiece, The cutting method according to claim 1 , wherein in the cutting step, the tip end is caused to cut into the workpiece with the base end inclined from the intended cutting plane.

3. 3. The cutting method according to claim 2, wherein in the cutting step, the base end is inclined from the planned cutting plane so that the base end forms an angle with respect to the planned cutting plane that is greater than 0° and smaller than the angle between the perpendicular line and the c-axis.

4. The cutting method according to claim 1, wherein the cutting blade is configured such that the tip end of the cutting blade is inclined relative to the base end opposite the tip end of the cutting blade when the cutting blade is stationary and not cutting into the workpiece.

5. The cutting method according to claim 4, wherein the cutting blade is configured such that, when the cutting edge is stationary and not cutting into the workpiece, the tip end forms an angle with respect to the base end that is greater than 0° and smaller than the angle between the perpendicular line and the c-axis.

6. The cutting blade is configured such that, when the cutting blade is stationary without cutting into the workpiece, the tip portion is not inclined relative to the base end opposite to the tip portion of the cutting blade, and when the cutting blade is rotated without cutting into the workpiece, the tip portion is inclined relative to the base end due to a force generated by the rotation of the cutting blade, 2. The cutting method according to claim 1, wherein in the cutting step, the tip portion is caused to cut into the workpiece in a state adjusted so that at least a portion of the force acting on the cutting blade from the workpiece and a force generated by rotation of the cutting blade are directed to cancel each other out.

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