Cutting method

Abstract

To provide a cutting method capable of suppressing deterioration in processing quality of a wafer with a cutting blade.SOLUTION: A cutting method that cuts a wafer with a scheduled cutting line using a cutting blade includes a facet area identification step 1001 of identifying a facet area by irradiating a wafer with excitation light from above the wafer and detecting the intensity of fluorescence generated from the wafer, and a cutting step 1002 of cutting the wafer along the planned cutting line with a cutting blade after performing the facet area identification step 1001. In the cutting step 1002, the facet area is cut under a different cutting condition than the other areas.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cutting method for cutting a wafer having a predetermined cutting line with a cutting blade. [Background technology]

[0002] For example, in the power device manufacturing process, multiple power devices are formed on a SiC wafer that has been cut from an ingot and made into a wafer, and then multiple power devices are manufactured by dividing this wafer.

[0003] SiC wafers with an outer diameter of 6 inches are widely distributed on the market, but device manufacturing equipment that can only handle SiC wafers up to 5 inches in diameter is also widely used. Therefore, the outer periphery of 6-inch SiC wafers is cut off with a cutting blade to reduce the diameter to 5 inches (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-054461 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the quality of processing with the cutting blade varies greatly depending on the wafer, with some wafers experiencing frequent chipping and cracking, or abnormal wear and meandering of the cutting blade.

[0006] An object of the present invention is to provide a cutting method capable of suppressing a decrease in the processing quality of a wafer with a cutting blade. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the cutting method of the present invention is a cutting method for cutting a wafer on which a planned cutting line has been set using a cutting blade, and comprises a facet region identifying step of irradiating the wafer with excitation light from above the wafer to detect the intensity of fluorescence generated from the wafer and identifying a facet region, and a cutting step of cutting the wafer along the planned cutting line with the cutting blade after performing the facet region identifying step, characterized in that in the cutting step, the facet region is cut under cutting conditions different from those for other regions.

[0008] In the cutting method, the cutting line may be set in a ring shape centered on the center of the wafer, and in the cutting step, the cutting blade may cut the wafer into a ring shape to reduce the diameter of the wafer.

[0009] In the cutting method, the wafer may be made of SiC. [Effects of the Invention]

[0010] The present invention has an effect of suppressing deterioration in the processing quality of a wafer with a cutting blade. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing a wafer to be processed by the cutting method according to the first embodiment. [Figure 2] FIG. 2 is a plan view of the wafer shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the flow of the cutting method according to the first embodiment. [Figure 4] FIG. 4 is a perspective view schematically showing a facet region specifying step of the cutting method shown in FIG. [Figure 5] FIG. 5 is a diagram schematically illustrating the configuration of the facet detection unit shown in FIG. [Figure 6] FIG. 6 is a plan view showing an example of a facet region detected by the facet detection unit shown in FIG. [Figure 7] FIG. 7 is a perspective view showing a cutting step of the cutting method shown in FIG. [Figure 8] FIG. 8 is a perspective view showing a wafer to be processed by the cutting method according to the second embodiment. [Figure 9] FIG. 9 is a plan view showing an example of a facet region detected by the facet detection unit in the facet region specifying step of the cutting method according to the second embodiment. [Figure 10] FIG. 10 is a perspective view showing a cutting step of the cutting method according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0013] [Embodiment 1] A cutting method according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a wafer to be processed by the cutting method according to the first embodiment. Fig. 2 is a plan view of the wafer shown in Fig. 1. Fig. 3 is a flowchart showing the flow of the cutting method according to the first embodiment.

[0014] (wafer) The cutting method according to the first embodiment is a method for cutting a wafer 1 shown in Figures 1 and 2. In the first embodiment, the wafer 1 shown in Figures 1 and 2, which is the processing target of the cutting method according to the first embodiment, is made of SiC (silicon carbide) and is formed in a disk shape as a whole. The wafer 1 has a linear orientation flat 2 indicating a crystal orientation and a linear sub-orientation flat 3 formed on its outer edge. In the first embodiment, the longitudinal directions of the orientation flats 2 and 3 are perpendicular to each other, and the length of the orientation flat 2 is longer than the length of the sub-orientation flat 3.

[0015] The wafer 1 has cutting lines 4 (shown by dashed lines in FIGS. 1 and 2 ) set on its outer edge. In the first embodiment, the cutting lines 4 have a circular planar shape, an outer diameter 4-1 that is smaller than the outer diameter 1-1 of the wafer 1, and are arranged coaxially with the wafer 1. That is, in the first embodiment, the cutting lines 4 are set in an annular shape centered on the center of the wafer 1. In the first embodiment, the outer diameter 1-1 of the wafer 1 is 6 inches, and the outer diameter 4-1 of the cutting lines 4 is 5 inches. After the wafer 1 is cut along the cutting lines 4, devices are formed on the surface 7. In the first embodiment, the devices are MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), MEMS (Micro Electro Mechanical Systems), or SBDs (Schottky Barrier Diodes), but the devices of the present invention are not limited to MOSFETs, MEMS, and SBDs.

[0016] Furthermore, in the first embodiment, the wafer 1 is made of SiC, but in the present invention, the material constituting the wafer 1 is not limited to SiC and may be, for example, LiTaO3 (lithium tantalate: LT) or GaN (gallium nitride). Note that in Fig. 1, the cutting lines 4 are shown by dashed lines on the back surface 8 behind the front surface 7 of the wafer 1, but in reality, the cutting lines 4 shown in Fig. 1 are imaginary lines and do not exist on the back surface 8 of the wafer 1.

[0017] In the first embodiment, the wafer 1 is formed by cutting from an ingot made of a single crystal of SiC. The ingot is generally doped with impurities such as nitrogen to impart conductivity. For this reason, the ingot is not uniformly doped with such impurities, and regions 10 with different crystal structures called facets (hereinafter referred to as facet regions and shown with hatched lines in FIGS. 1 and 2 ) may be formed during the growth process of the single crystal of SiC. The impurity concentration in the facet regions 10 is higher than that in other regions 11 (hereinafter referred to as non-facet regions and shown with white backgrounds in FIGS. 1 and 2 ). Thus, the impurity concentration in the facet regions 10 differs from that in the non-facet regions 11. The facet regions 10 have a higher refractive index and a higher energy absorption rate than the non-facet regions 11. Thus, the wafer 1 may include the facet regions 10. In the first embodiment, the wafer 1 includes the facet regions 10.

[0018] (Cutting method) The cutting method according to the first embodiment is a cutting method in which the above-described wafer 1 is cut by a cutting blade 81 (shown in FIG. 7) along the cutting line 4. As shown in FIG. 3, the cutting method includes a facet region specifying step 1001 and a cutting step 1002.

[0019] (Facet area identification step) Fig. 4 is a perspective view schematically showing a facet region specifying step of the cutting method shown in Fig. 3. Fig. 5 is a diagram schematically showing the configuration of the facet detection unit shown in Fig. 4. Fig. 6 is a plan view showing an example of a facet region detected by the facet detection unit shown in Fig. 5.

[0020] 4 irradiates the wafer 1 with excitation light 261 from a facet detection unit 21 above the wafer 1, detects the intensity of fluorescence 262 emitted from the wafer 1, and identifies the facet region 10. In the facet region identifying step 1001, the facet region identifying device 20 shown in FIG. 4 suction-holds the front surface 7 side of the wafer 1 onto the holding table 22.

[0021] The facet detection unit 21 of the facet region identifying device 20 is disposed opposite the back surface 8 of the wafer 1 held by suction on the holding table 22, and irradiates the back surface 8 of the wafer 1 with excitation light 261 of a predetermined wavelength to detect the intensity of fluorescence 262 specific to SiC. As shown in Fig. 5, the facet detection unit 21 includes a case 23 disposed opposite the wafer 1 held by suction on the holding table 22, an excitation light irradiator 24, and a light receiver 25. The case 23 is formed in a box shape with an opening at the bottom facing the wafer 1 held by suction on the holding table 22.

[0022] The excitation light irradiation unit 24 irradiates the back surface 8 of the wafer 1 held on the holding table 22 with excitation light 261. The excitation light irradiation unit 24 includes a light source 26 that oscillates excitation light 261 in a wavelength range (e.g., 365 nm to 375 nm) that is absorbed by the wafer 1 and has a low output (e.g., 0.1 W) that does not cause laser processing on the wafer 1, a mirror 27 that reflects the excitation light 261 oscillated from the light source 26, and a condenser lens 28 that collects the excitation light 261 reflected by the mirror 27 and irradiates the wafer 1 with the light.

[0023] Light source 26, mirror 27, and condenser lens 28 are disposed within case 23. Light source 26 has, for example, a GaN-based light-emitting element, and irradiates mirror 27 with excitation light 261 including light of a wavelength (for example, 365 nm) that is absorbed by SiC ingot 200. Mirror 27 reflects excitation light 261, which is light of a wavelength of, for example, 365 nm to 375 nm, and transmits light of wavelengths other than, for example, 365 nm to 375 nm.

[0024] When the wafer 1 is irradiated with the excitation light 261, the wafer 1 absorbs the excitation light 261 and is excited by the excitation light 261 to generate fluorescence 262. For example, if the wavelength of the excitation light 261 is 365 nm, the excitation light 261 penetrates to a depth of about 10 μm from the rear surface 8 of the wafer 1. Then, fluorescence 262 is generated from a plate-shaped region with a thickness of about 10 μm on the rear surface 8 side of the wafer 1.

[0025] The light receiving unit 25 collects and receives fluorescence 262 generated when the wafer 1 is excited by the excitation light 261. The light receiving unit 25 is disposed within the case 23 and includes an annular elliptical mirror 31 having a reflecting surface 30 on the inside, a filter 32, and a light receiving unit 33. The elliptical mirror 31 is disposed closer to the holding table 22 than the condensing lens 28, and the reflecting surface 30 corresponds to a part of the curved surface of a spheroid obtained by rotating an ellipse 34 having a major axis extending in the vertical direction and a minor axis extending in the horizontal direction around the major axis.

[0026] The elliptical mirror 31 has two focal points 35, 36, and condenses light emitted from one of the focal points (for example, the focal point 35) at the other focal point (for example, the focal point 36). One focal point 35 of the elliptical mirror 31 is designed to approximately coincide with the focus of the condenser lens 28. The other focal point 36 of the elliptical mirror 31 is set at the light-receiving unit 33. The elliptical mirror 31 reflects the fluorescence 262 emitted by the wafer 1 held on the holding table 22 at the reflecting surface 30, passes the fluorescence 262 through the filter 32, and then receives it at the light-receiving unit 33.

[0027] The filter 32 is disposed between the mirror 27 and the light receiving unit 33, and is equipped with an IR filter that transmits light 263 with a wavelength of 750 nm or more from the fluorescence 262 generated by the wafer 1 and transmitted through the focusing lens 28, and blocks light with a wavelength of less than 750 nm.

[0028] The light receiving unit 33 receives light 263 that is transmitted by the filter 32 and is part of the fluorescence 262 generated from the wafer 1 and transmitted through the condenser lens 28, generates a signal indicating the intensity of the received light 263, and outputs the generated signal to the control unit 70 of the facet region identifying device 20. Here, the intensity is weaker in regions of the wafer 1 where the excitation light 261 irradiates and where the impurity concentration is higher. In other words, the intensity of the light 263 from the facet region 10 is less than the intensity of the light 263 from the non-facet region 11.

[0029] Furthermore, although not shown, the facet detection unit 21 includes a focal point position adjustment means that raises and lowers the case 23 to adjust the position of the focal point of the excitation light 261 in the Z-axis direction, and this focal point position adjustment means includes, for example, a ball screw connected to the case 23 and extending in the Z-axis direction, and a motor that rotates this ball screw.

[0030] The control unit 70 controls each of the components of the facet region identifying device 20 to cause the facet region identifying device 20 to perform an operation to identify the facet region 10 of the wafer 1. The control unit 70 is a computer having an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or RAM (random access memory), and an input / output interface device. The arithmetic processing device of the control unit 70 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs control signals for controlling the facet region identifying device 20 to the above-mentioned components of the facet region identifying device 20 via the input / output interface device, thereby realizing the functions of the control unit 70.

[0031] The control unit 70 is also connected to a display unit configured with a liquid crystal display device or the like that displays the status of the machining operation, images, etc., and an input unit (not shown) that the operator uses to register machining content information, etc. The input unit is configured with at least one of a touch panel provided on the display unit and an external input device such as a keyboard.

[0032] In facet region identifying step 1001, control unit 70 of facet region identifying device 20 irradiates excitation light 261 onto back surface 8 of wafer 1 held on holding table 22 at predetermined intervals while moving facet detection unit 21 and holding table 22 relatively, and detects the intensity of light 263 that has passed through filter 32 out of fluorescence 262 from back surface 8 of wafer 1 at predetermined intervals with light receiving unit 33. At this time, excitation light 261 emitted from light source 26 is reflected by mirror 27 and guided to condenser lens 28, where it is condensed and irradiated onto back surface 8 of wafer 1.

[0033] In embodiment 1, in the facet region identification step 1001, the control unit 70 of the facet region identification device 20 rotates the holding table 22 around an axis parallel to the vertical direction (also called the Z-axis direction), and irradiates the excitation light 261 while moving the holding table 22 and the facet detection unit 21 relatively along the radial direction of the holding table 22 so that the distance from the axis of the holding table 22 to the position where the facet detection unit 21 faces the outer edge of the wafer 1 along the Z-axis direction gradually becomes shorter.

[0034] When the back surface 8 of the wafer 1 is irradiated with the excitation light 261, the wafer 1 generates fluorescence 262 having a wavelength different from that of the excitation light 261 (for example, a wavelength of 750 nm or more), and the fluorescence 262 is emitted from the wafer 1. After the fluorescence 262 passes through the condenser lens 28 and the mirror 27, only light 263 having a wavelength of 750 nm or more passes through the filter 32. The light 263 that has passed through the filter 32 is received by the light receiving unit 33, and the intensity of the light 263 is detected by the light receiving unit 33. The light receiving unit 33 outputs a signal corresponding to the intensity of the received light 263 to the control unit 70.

[0035] Furthermore, facet region identifying device 20 includes an X-axis position detection unit that detects the X-axis position of wafer 1 held on holding table 22 at a position opposite facet detection unit 21 along the Z-axis, and a Y-axis position detection unit that detects the Y-axis position of wafer 1 held on holding table 22 at a position opposite facet detection unit 21 along the Z-axis. The X-axis position detection unit and Y-axis position detection unit output the detection results to control unit 70. The X-axis and Y-axis directions are parallel to the horizontal direction and perpendicular to each other.

[0036] The control unit 70 calculates the X-axis and Y-axis positions of the wafer 1 held on the holding table 22 at which the excitation light 261 is irradiated, i.e., the XY coordinates, based on the detection result of the X-axis position detection unit and the detection result of the Y-axis position detection unit that detects the position in the Y-axis direction. The control unit 70 of the facet region identifying device 20 stores the calculated XY coordinates of the position of the wafer 1 held on the holding table 22 at which the excitation light 261 is irradiated and the intensity of the light 263 in association with each other in the storage device.

[0037] The control unit 70 calculates the XY coordinates of the position where the excitation light 261 is irradiated on the SiC ingot 200 held on the holding table 22, and the intensity of the light 263, stored in the storage device, and calculates the XY coordinates of each position on the outer edge of the facet region 10, where the intensity of the light 263 is equal to or less than a predetermined value. The control unit 70 temporarily stores the calculated XY coordinates of each position on the outer edge of the facet region 10 in the storage device.

[0038] In the first embodiment, the X-axis and Y-axis positions of the wafer 1 held on the holding table 22 of the facet region identifying device 20, where the excitation light 261 is irradiated, are determined based on a predetermined reference position 100 (an example of which is shown in FIG. 6 ). In the first embodiment, the X-axis and Y-axis positions are determined by the distances from the reference position 100 in the X-axis and Y-axis directions. In the first embodiment, the XY coordinates represented by the X-axis and Y-axis directions of the facet region identifying device 20 (the coordinates indicated by the distance in the X-axis direction from the reference position 100 indicating the position in the X-axis direction and the distance in the Y-axis direction from the reference position 100 indicating the position in the Y-axis direction) can indicate any positions in the X-axis and Y-axis directions of the wafer 1 held on the holding table 22. In FIG. 6 , the reference position 100 is set to a position that halves the length of the orientation flat 2, the X-axis direction is set to a direction parallel to the orientation flat 2, and the Y-axis direction is set to a direction parallel to the sub-orientation flat 3.

[0039] (Cutting step) Fig. 7 is a perspective view showing the cutting step of the cutting method shown in Fig. 2. In the cutting step 1002, the wafer 1 is cut along the planned cutting line 4 with the cutting blade 81 after the facet region specifying step 1001 is performed.

[0040] In the first embodiment, in the cutting step 1002, the cutting device 80 suction-holds the front surface 7 side of the wafer 1 on a chuck table (not shown). Also, in the cutting step 1002, the control unit (not shown) of the cutting device 80 determines whether the line to cut 4 passes through the facet region 10 identified in the facet region identifying step 1001, and identifies the XY coordinates of the position where the line to cut 4 passes through the facet region 10 while passing through the facet region 10.

[0041] In embodiment 1, in the cutting step 1002, as shown in FIG. 7, the control unit of the cutting device 80 causes the cutting blade 81, which is rotated around its axis by the spindle 82 based on predetermined cutting conditions, to cut into the outer edge of the wafer, and also rotates the chuck table, i.e., the wafer 1, around its axis, so that the cutting blade 81 cuts the wafer 1 into a ring shape along the intended cutting line 4, thereby reducing the diameter of the wafer 1.

[0042] In the first embodiment, in the cutting step 1002, the cutting conditions when the cutting blade 81 cuts the facet region 10 are different from the cutting conditions when the non-facet region 11 is cut. That is, in the cutting step 1002, the facet region 10 is cut under different cutting conditions from the non-facet region 11. In the first embodiment, in the cutting step 1002, the cutting conditions when the cutting blade 81 cuts the facet region 10 are set to cutting conditions in which the load (hereinafter referred to as the cutting load) applied to the cutting blade 81 and the wafer 1 during cutting is smaller than the cutting conditions when the non-facet region 11 is cut.

[0043] In the first embodiment, in the cutting step 1002, the rotational speed of the chuck table about its axis, which is a cutting condition when the cutting blade 81 cuts the facet region 10, is set to be slower than the rotational speed of the chuck table about its axis, which is a cutting condition when the cutting blade 81 cuts the non-facet region 11. However, the present invention is not limited to this, and in the cutting step 1002, the rotational speed of the spindle 82, which is a cutting condition when the cutting blade 81 cuts the facet region 10, may be set to be slower than the rotational speed of the spindle 82, which is a cutting condition when the cutting blade 81 cuts the non-facet region 11, or in the cutting step 1002, the cutting depth of the cutting blade 81 when cutting the facet region 10 may be set shallower than the cutting depth of the cutting blade 81, which is a cutting condition when the cutting blade 81 cuts the non-facet region 11, and the height of the cutting blade 81 in the Z-axis direction only in the facet region 10 may be gradually lowered to cut only the facet region 10 with the cutting blade 81 multiple times (so-called multi-stage cutting). In the present invention, more than one of the rotation speed of the chuck table, the rotation number of the spindle 82, and multi-stage cutting may be combined.

[0044] The cutting method according to the first embodiment ends in cutting step 1002, in which the cutting blade 81 cuts the entire circumference of the cutting line 4 to reduce the diameter of the wafer 1. After devices are formed on the front surface 7 of the reduced-diameter wafer 1, the reduced-diameter wafer 1 is divided into individual devices.

[0045] In an ingot made of SiC, a region called a facet region 10 is formed during the growth process. The facet region 10 remains in a wafer 1 cut from the ingot, and the facet region 10 has a higher refractive index and different physical properties such as resistivity and defect density than the other non-facet region 11. As a result of extensive research, the applicant of the present application has found that the facet region 10 of the wafer 1 deteriorates processing quality (frequent chipping and cracking) and causes abnormalities in the cutting blade 81 (abnormal wear, meandering, etc.).

[0046] Therefore, as described above, the cutting method of embodiment 1 identifies the facet region 10 in a facet region identification step 1001 before cutting the wafer 1, and then cuts the facet region 10 in a cutting step 1002 under cutting conditions that result in a smaller cutting load than the other non-facet regions 11.

[0047] For this reason, the cutting method according to the first embodiment can cut the facet region 10 under cutting conditions that reduce the risk of deterioration in processing quality and abnormalities occurring in the cutting blade 81, and can suppress chipping and cracks when cutting the facet region 10, and can suppress abnormal wear and meandering of the cutting blade 81. As a result, the cutting method according to the first embodiment has the effect of suppressing deterioration in the processing quality of the wafer 1 by the cutting blade 81.

[0048] [Embodiment 2] A cutting method according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 8 is a perspective view showing a wafer to be processed by the cutting method according to the second embodiment. Fig. 9 is a plan view showing an example of a facet region detected by a facet detection unit in the facet region specifying step of the cutting method according to the second embodiment. Fig. 10 is a perspective view showing the cutting step of the cutting method according to the second embodiment. In Figs. 8, 9, and 10, the same parts as those in the first embodiment are designated by the same reference numerals, and their description will be omitted.

[0049] 8, a wafer 1-2 to be processed by the cutting method according to the second embodiment has a plurality of cutting lines 6 formed in a grid pattern on a surface 7, and devices 5 formed in areas defined by the cutting lines 6 on the surface 7. In the second embodiment as well, the wafer 1 includes a facet region 10.

[0050] In the cutting method according to the second embodiment, in a facet region specifying step 1001, the front surface 7 side of the wafer 1 on which the devices 5 are formed is suction-held on a holding table 22, and excitation light 261 is irradiated onto the back surface 8 on which the devices 5 are not formed, thereby specifying facet regions 10 as shown in Fig. 9, as in the first embodiment. In addition, in the cutting method according to the second embodiment, in a cutting step 1002, after the cutting device 80 suction-holds the back surface 8 side of the wafer 1 on a chuck table (not shown), a control unit (not shown) determines whether each of the lines to cut 4 passes through the facet regions 10 obtained in the facet region specifying step 1001, and specifies a line to cut 6 (shown by a dashed line in Fig. 9, hereinafter denoted by reference numeral 6-1) that passes through the facet region 10.

[0051] In embodiment 2, in the cutting step 1002, as shown in FIG. 10, the control unit of the cutting device 80 causes the cutting blade 81, which is rotated around its axis by the spindle 82 based on predetermined cutting conditions, to cut into each of the intended cutting lines 6, 6-1, and moves the chuck table and the cutting blade 81 relatively along the intended cutting lines 6, 6-1, so that the cutting blade 81 cuts the intended cutting lines 6, 6-1 of the wafer 1, dividing the wafer 1 into individual devices 5.

[0052] In the second embodiment, in the cutting step 1002, the cutting conditions when the cutting blade 81 cuts the line to cut 6-1 that passes through the facet region 10 are different from the cutting conditions when cutting the line to cut 6 that passes only through the non-facet region 11. That is, in the cutting step 1002, the facet region 10 is cut under different cutting conditions than the non-facet region 11. In the second embodiment, in the cutting step 1002, the cutting conditions when the cutting blade 81 cuts the line to cut 6-1 that passes through the facet region 10 are set to cutting conditions that result in a smaller cutting load on the cutting blade 81 and the wafer 1 than the cutting conditions when cutting the line to cut 6 that passes only through the non-facet region 11.

[0053] In the second embodiment, as in the first embodiment, in the cutting step 1002, the movement speed of the chuck table, which is a cutting condition when the cutting blade 81 cuts the line to be cut 6-1 passing through the facet region 10, is set to be slower than the movement speed of the chuck table, which is a cutting condition when the cutting blade 81 cuts the line to be cut 6-1 passing through the facet region 10, is set to be slower than the movement speed of the chuck table, which is a cutting condition when the cutting blade 81 cuts the line to be cut 6-1 passing through the facet region 10, is set to be slower than the rotation speed of the spindle 82, which is a cutting condition when the cutting blade 81 cuts the line to be cut 6-1 passing through the facet region 10, is set to be slower than the rotation speed of the spindle 82, which is a cutting condition when the cutting blade 81 cuts the line to be cut 6-1 passing through the facet region 10, is set to be

[0054] The cutting method according to the second embodiment ends after cutting step 1002 in which cutting blade 81 cuts each of the cutting lines 6, 6-1 to divide the wafer 1 into individual devices 5. In cutting step 1002, a circular dicing tape 12 having a larger diameter than the wafer 1 is attached to the back surface 8 of the wafer 1, an annular frame 13 is attached to the outer edge of the dicing tape 12, and the cutting blade 81 is caused to cut into the wafer 1 until it reaches the dicing tape 12.

[0055] The cutting method of embodiment 2 identifies the facet region 10 in a facet region identification step 1001 before cutting the wafer 1, and cuts the facet region 10 in a cutting step 1002 under cutting conditions that result in a smaller cutting load than the other non-facet regions 11.As a result, similar to embodiment 1, it has the effect of suppressing a decrease in the processing quality of the wafer 1 by the cutting blade 81.

[0056] The present invention is not limited to the above-described embodiment, and can be implemented in various modifications without departing from the gist of the present invention. [Explanation of symbols]

[0057] 1 wafer 4,6,6-1 Planned cutting line 10 Facet Area 11 Non-faceted area (other areas) 81 Cutting blade 261 Excitation Light 262 Fluorescence 1001 Facet Area Identification Step 1002 Cutting Step

Claims

1. A cutting method for cutting a wafer having a predetermined cutting line with a cutting blade, comprising: a facet region identifying step of irradiating the wafer with excitation light from above the wafer, detecting the intensity of fluorescence emitted from the wafer, and identifying a facet region; a cutting step of cutting the wafer along the planned cutting line with the cutting blade after the facet region specifying step is performed; In the cutting step, the facet region is cut under cutting conditions different from those for other regions.

2. the planned cutting line is set in a ring shape centered on the center of the wafer, The cutting method according to claim 1 , wherein the cutting step cuts the wafer into a ring shape with the cutting blade to reduce the diameter of the wafer.

3. 3. The cutting method according to claim 1, wherein the wafer is made of SiC.

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