Wafer processing method

Abstract

To provide a wafer processing method capable of easily processing a planned dividing line even in the case of a wafer having a metal layer laminated on the back side.SOLUTION: A wafer processing method for a wafer. The wafer has: on a front side, a plurality of intersecting planned division lines and a plurality of devices respectively formed in areas partitioned by the planned division lines; and a metal layer laminated on the back side. The wafer processing method includes: a mark forming step 1002 of forming marks indicating the positions of the planned division lines of the wafer, on the back side; and a dicing step 1003 of dicing the wafer from the back side on the basis of the marks formed in the mark forming step 1002 to divide it into individual chips.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for processing a wafer having a plurality of devices formed on its front surface and a metal layer laminated on its back surface. [Background technology]

[0002] In order to prevent foreign matter from adhering to devices during dicing, it is common to affix tape to the front side of the wafer before dicing (see, for example, Patent Document 1).

[0003] In the dicing method described in Patent Document 1, when dicing from the back side of the wafer, an infrared camera is used to detect the pattern on the front side, the positions of the intended division lines are identified based on the pattern, and the wafer is diced along the intended division lines with a cutting blade. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-232255 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of wafers that have a metal layer laminated on the back side, it is difficult to identify the position of the intended dividing line using an infrared camera, and improvement is urgently needed.

[0006] An object of the present invention is to provide a wafer processing method capable of easily processing a dividing line even in a wafer having a metal layer laminated on the back surface side. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems and achieve the object, the wafer processing method of the present invention is a method for processing a wafer having, on its front side, a plurality of intersecting planned dividing lines and a plurality of devices formed in each area partitioned by the planned dividing lines, and having a metal layer laminated on its back side, and is characterized in comprising a mark forming step of forming marks on the back side of the wafer indicating the positions of the planned dividing lines, and a dicing step of dicing the wafer from the back side of the wafer based on the marks formed in the mark forming step to divide it into individual chips.

[0008] In the wafer processing method, the mark forming step may include holding the front side of the wafer with a holding table including a holding surface at least a portion of which is made of a transparent material, imaging the front side of the wafer through the holding surface to detect the planned division line, and forming the mark based on the detected planned division line.

[0009] In the wafer processing method, the marks may be formed in areas that correspond to the intended dividing lines and that are to be removed in the dicing step.

[0010] In the wafer processing method, the mark may be formed in a cross shape, and may be formed in an area that corresponds to an intersection of the planned dividing lines and is to be removed in the dicing step.

[0011] In the above-described wafer processing method, the wafer may be made of SiC. Effect of the Invention

[0012] The present invention has an effect of easily processing the dividing lines even in a wafer having a metal layer laminated on the back surface side. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view that illustrates a wafer to be processed by the wafer processing method according to the first embodiment. [Diagram 2]FIG. 2 is a flowchart showing the flow of the wafer processing method according to the first embodiment. [Diagram 3] FIG. 3 is a perspective view showing the wafer after the tape disposing step of the wafer processing method shown in FIG. [Figure 4] FIG. 4 is a perspective view showing an example of the configuration of a processing apparatus that performs the mark forming step of the wafer processing method shown in FIG. [Diagram 5] FIG. 5 is a plan view of the wafer after the mark forming step of the wafer processing method shown in FIG. 2, viewed from the back surface side. [Figure 6] FIG. 6 is a plan view of another example of the wafer shown in FIG. 5 as viewed from the back surface side. [Figure 7] FIG. 7 is a perspective view that illustrates a dicing step of the wafer processing method illustrated in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The form (embodiment) 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 embodiment. Furthermore, the components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the gist of the present invention.

[0015] [Embodiment 1] The wafer processing method according to the first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a typical example of a wafer to be processed by the wafer processing method according to the first embodiment. Fig. 2 is a flow chart showing the flow of the wafer processing method according to the first embodiment.

[0016] (Wafer) The wafer processing method according to the first embodiment is a method of dicing (corresponding to processing) a wafer 1. The wafer 1 shown in Fig. 1, which is the processing target of the wafer processing method according to the first embodiment, is a disk-shaped semiconductor device wafer or optical device wafer, etc., with the substrate 2 being made of silicon, sapphire, gallium arsenide, SiC (silicon carbide), etc. In the first embodiment, the substrate 2 of the wafer 1 is made of SiC.

[0017] 1, the wafer 1 includes a device region 4 on a surface 3 of a substrate 2, and a peripheral excess region 5 surrounding the device region 4. The device region 4 includes, on the surface 3 side, a plurality of intersecting division lines 6 and devices 7 formed in each of the regions partitioned by the division lines 6.

[0018] The device 7 is, for example, an integrated circuit such as an IC (Integrated Circuit) or an LSI (Large Scale Integration), an image sensor such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), an optical element such as an LED (Light-Emitting Diode), or a memory (semiconductor memory device). The peripheral excess region 5 surrounds the entire device region 4 and is a region on the front surface 3 of the substrate 2 where no device 7 is formed.

[0019] In the first embodiment, the wafer 1 has a metal layer 9 laminated on a back surface 8 behind the front surface 3 of the substrate 2. Since the wafer 1 has the metal layer 9 formed on the back surface 8, even if the wafer 1 is imaged from the back surface 8 side with an infrared camera, the intended dividing lines 6 cannot be detected.

[0020] (Wafer processing method) Next, a wafer processing method according to the first embodiment will be described. The wafer processing method according to the first embodiment is a method of dicing the wafer 1 and dividing it into individual chips 10. The chips 10 include a part of the substrate 2 and the chips 10 formed on the surface 3 of the substrate 2. The wafer processing method according to the first embodiment includes a tape disposing step 1001, a mark forming step 1002, and a dicing step 1003, as shown in FIG. 2.

[0021] (Tape placement step) Fig. 3 is a perspective view showing a wafer after a tape application step of the wafer processing method shown in Fig. 2. The tape application step 1001 is a step of applying a tape 11 to the front surface 3 of the wafer 1. In the first embodiment, in the tape application step 1001, as shown in Fig. 3, the center of a disk-shaped tape 11 having a diameter larger than that of the wafer 1 is adhered to the front surface 3 of the wafer 1, and an annular frame 12 having an inner diameter larger than the outer diameter of the wafer 1 is adhered to the outer edge of the tape 11.

[0022] In the first embodiment, the tape 11 is an adhesive tape that includes a base layer made of a non-adhesive and flexible resin and a glue layer that is laminated on the base layer and made of an adhesive and flexible resin, and the glue layer is attached to the wafer 1 and the frame 12. However, in the present invention, the tape 11 may be a sheet that does not include a glue layer and is made of a thermoplastic resin, and that is composed only of a base layer that develops adhesive strength when heated and is thermocompressed to the wafer 1 and the frame 12.

[0023] In embodiment 1, in the tape placement step 1001, the front surface 3 of the wafer 1 is adhered to a tape 11 having a frame 12 attached to its outer edge, and the wafer 1 is supported by the frame 12, exposing the metal layer 9 on the back surface 8 side of the wafer 1.

[0024] (Processing equipment) The mark forming step 1002 of the wafer processing method shown in Fig. 2 is performed by a processing apparatus 30 shown in Fig. 4. Next, the processing apparatus 30 will be described. Fig. 4 is a perspective view showing a configuration example of a processing apparatus that performs the mark forming step of the wafer processing method shown in Fig. 2.

[0025] 4 is a laser processing apparatus that holds the wafer 1 on a holding table 42 of a holding unit 40 and forms marks 13 indicating the positions of the planned dividing lines 6 of the wafer 1 in a metal layer 9 laminated on the back surface 8 side. As shown in FIG. 4, the processing apparatus 30 includes the holding unit 40, a laser beam irradiation unit 50, a moving unit 60, an upper imaging unit 70, a lower imaging unit 80, and a control unit 100.

[0026] As shown in FIG. 4, the holding unit 40 includes a table base 41 that is moved by a moving unit 60 in an X-axis direction that is parallel to the horizontal direction and a Y-axis direction that is parallel to the horizontal direction and perpendicular to the X-axis direction, and a holding table 42 that is rotatably mounted on the table base 41 around an axis that is parallel to the Z-axis direction that is aligned vertically.

[0027] In embodiment 1, the table base 41 comprises a lower plate 411 which is moved in the X-axis and Y-axis directions by the moving unit 60 and is parallel to the horizontal direction, a side plate 412 standing upright from the outer edge of the lower plate 411, and an upper plate 413 whose outer edge is connected to the upper end of the side plate 412, which is parallel to the lower plate 411, and which has a circular hole in the center having the same diameter as the holding portion 44 described later.

[0028] The holding table 42 holds the wafer 1 on a holding surface 441, and is supported rotatably about its axis by the upper plate 413. As shown in Fig. 6, the holding table 42 includes an annular base 43 having an opening at the center and supported rotatably about an axis parallel to the Z-axis direction by the upper plate 413, and a disk-shaped holding part 44 attached within the opening of the annular base 43 and made of a transparent material.

[0029] The holding unit 44 is made of a transparent material such as quartz glass, borosilicate glass, sapphire, calcium fluoride, lithium fluoride, or magnesium fluoride, and its upper surface is a holding surface 441 that holds the wafer 1. That is, the holding table 42 includes the holding surface 441. In the first embodiment, the holding unit 44 has the front surface 3 side of the wafer 1 placed on the holding surface 441 via the tape 11. The holding unit 44 has a suction groove formed on the holding surface 441 that is connected to a vacuum suction source.

[0030] The holding surface 441 of the holding table 42 is sucked by a vacuum suction source, so that the wafer 1 placed on the holding surface 441 is sucked and held on the holding surface 441 via the tape 11. In the first embodiment, the holding portion 44 of the holding table 42 is made of a transparent material, so that at least a portion of the holding surface 441 is made of a transparent material.

[0031] The moving unit 60 includes an X-axis moving unit 61 which is a processing feed unit, a Y-axis moving unit 62 which is an indexing feed unit, and a rotational moving unit 63 which rotates the holding table 42 about an axis parallel to the Z-axis direction.

[0032] The X-axis moving unit 61 is installed on the apparatus body 31. The X-axis moving unit 61 moves the moving table 32, on which the Y-axis moving unit 62 is installed, in the X-axis direction, thereby relatively moving the holding table 42 and the laser beam irradiation unit 50 in the X-axis direction. The X-axis moving unit 61 moves the holding table 42 in the X-axis direction across a carry-in / out area where the wafer 1 is carried in and out of the holding table 42, and a processing area where the wafer 1 held by the wafer 1 is laser processed.

[0033] The Y-axis moving unit 62 is installed on the moving table 32 which is moved in the X-axis direction by the X-axis moving unit 61. The Y-axis moving unit 62 moves the lower plate 411 of the table base 41 of the holding unit 40 in the Y-axis direction, thereby relatively moving the holding table 42 and the laser beam irradiation unit 50 in the Y-axis direction.

[0034] The X-axis moving unit 61 and the Y-axis moving unit 62 each include a well-known ball screw that is rotatable around its axis, a well-known motor that rotates the ball screw around its axis, and a well-known guide rail that supports the moving table 32 or the table base 41 so that it can move freely in the X-axis direction or the Y-axis direction.

[0035] The rotary movement unit 63 rotates the holding table 42 around an axis parallel to the Z-axis direction. The rotary movement unit 63 rotates the holding table 42 around the axis within a range of more than 180 degrees and less than 360 degrees. The rotary movement unit 63 includes a motor 631 fixed to the side plate 412 of the table base 41, a pulley 632 connected to an output shaft of the motor 631, and a belt 633 attached by being wound around the outer periphery of the annular base 43 of the holding table 42 and rotated around the axis by the pulley 632.

[0036] When the motor 631 is rotated, the rotary transfer unit 63 rotates the holding table 42 about its axis via the pulley 632 and the belt 633. In the first embodiment, the rotary transfer unit 63 can rotate the holding table 42 by 220 degrees in both one direction about the axis and the other direction opposite to the one direction.

[0037] The laser beam irradiation unit 50 is a processing unit that focuses and irradiates a pulsed laser beam onto the wafer 1 held on the holding surface 441 of the holding table 42, thereby performing laser processing on the metal layer 9 of the wafer 1. In the first embodiment, a part of the laser beam irradiation unit 50 is disposed at the tip of a support column 34, the base end of which is supported by an upright column 33 standing upright from the apparatus body 31, as shown in FIG.

[0038] The laser beam irradiation unit 50 includes an oscillator that emits a laser beam having a wavelength that is absorbed by the metal layer 9, and a condenser lens that condenses the laser beam emitted from the oscillator and irradiates the wafer 1 with the laser beam.

[0039] The upper imaging unit 70 is fixed to the tip of the support column 34. In the first embodiment, the upper imaging unit 70 is disposed at a position aligned with the condenser lens of the laser beam irradiation unit 50 in the X-axis direction. The upper imaging unit 70 includes a plurality of imaging elements that image the wafer 1 held on the holding table 42 from above. The imaging elements are, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element. The upper imaging unit 70 images the wafer 1 held on the holding portion 44 of the holding table 42, and outputs the obtained image to the control unit 100.

[0040] The lower imaging unit 80 images the front surface 3 of the wafer 1 held on the holding table 42 through the holding portion 44 of the holding table 42. The lower imaging unit 80 images the front surface 3 side of the wafer 1 held on the holding portion 44 of the holding table 42 from below the wafer 1 through the holding portion 44.

[0041] The lower imaging unit 80 is disposed adjacent to the moving table 32 in the Y-axis direction and adjacent to the erected column 33 in the X-axis direction. The lower imaging unit 80 is disposed so as to be movable in the Z-axis direction by a Z-axis moving unit 64 provided on an erected column 35 erected from the apparatus body 31. In the first embodiment, the lower imaging unit 80 is attached to the tip of a horizontally extending member 65 whose base end is movable in the Z-axis direction by the Z-axis moving unit 64.

[0042] The Z-axis moving unit 64 includes a well-known ball screw that is rotatable around its axis, a well-known motor that rotates the ball screw around its axis, and a well-known guide rail that supports the lower imaging unit 80 so that it can move in the Z-axis direction.

[0043] The lower imaging unit 80 is disposed below the holding portion 44 of the holding table 42, by entering between the lower plate 411 and the upper plate 413 of the table base 41 moved by the Y-axis moving unit 62. The lower imaging unit 80 includes an imaging element that images the wafer 1 held on the holding table 42 from below through the holding portion 44. The imaging element is, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element. The lower imaging unit 80 images the wafer 1 held on the holding table 42, and outputs the obtained image to the control unit 100.

[0044] The processing device 30 also includes an X-axis position detection unit (not shown) for detecting the position of the holding table 42 in the X-axis direction, and a Y-axis position detection unit (not shown) for detecting the position of the holding table 42 in the Y-axis direction. 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 direction or the Y-axis direction, and a reading head. The X-axis position detection unit and the Y-axis position detection unit output the positions of the holding table 42 in the X-axis direction and the Y-axis direction to the control unit 100.

[0045] The positions of the holding table 42 in each axial direction detected by each position detection unit are determined based on a predetermined reference position of the processing device 30. That is, in the processing device 30 according to the first embodiment, each position is determined based on a predetermined reference position.

[0046] The control unit 100 controls each of the above-mentioned components of the processing apparatus 30, and causes the processing apparatus 30 to perform processing operations on the wafer 1. The control unit 100 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 a RAM (random access memory), and an input / output interface device. The arithmetic processing device of the control unit 100 performs arithmetic processing according to a computer program stored in the storage device, and outputs control signals for controlling the processing apparatus 30 to the above-mentioned components of the processing apparatus 30 via the input / output interface device.

[0047] The machining device 30 is also connected to a display unit (not shown) that is connected to the control unit 100 and is configured with a liquid crystal display device or the like for displaying the state of the machining operation, images, etc., and an input unit that is connected to the control unit 100 and is used by an operator to register machining content information, etc. In the first embodiment, 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.

[0048] (Mark formation step) Fig. 5 is a plan view of the wafer after the mark forming step of the wafer processing method shown in Fig. 2, as viewed from the back surface side. Fig. 6 is a plan view of another example of the wafer shown in Fig. 5, as viewed from the back surface side. The mark forming step 1002 is a step of forming marks 13 on the back surface 8, which indicate the positions of the planned dividing lines 6 of the wafer 1.

[0049] In the first embodiment, in the mark forming step 1002, the processing conditions of the processing device 30 are registered in the control unit 100 by the operator, and the front surface 3 side of the wafer 1 after the tape disposing step 1001 and before cutting is placed via the tape 11 on the holding surface 441 of the holding table 42 positioned in the carry-in / out area. In the first embodiment, in the mark forming step 1002, when the control unit 100 receives an instruction to start the processing operation from the operator, the processing device 30 starts the processing operation, i.e., the mark forming step 1002.

[0050] In the first embodiment, in the mark forming step 1002, when the processing device 30 starts the processing operation, the control unit 100 suction-holds the front surface 3 side of the wafer 1 on the holding surface 441 via the tape 11, and exposes the back surface 8 of the wafer 1 upward. In the first embodiment, in the mark forming step 1002, the control unit 100 of the processing device 30 controls the X-axis moving unit 61 and the Y-axis moving unit 62 to position the lower imaging unit 80 below the wafer 1 held by the holding portion 44 of the holding table 42.

[0051] In the first embodiment, in the mark forming step 1002, the control unit 100 of the processing device 30 images the wafer 1 from below through the holder 44 and the tape 11 with the lower imaging unit 80, acquires the captured image, and detects the planned division lines 6 from the acquired image. In the first embodiment, in the mark forming step 1002, the control unit 100 of the processing device 30 controls the X-axis moving unit 61 and the Y-axis moving unit 62 to align the condenser lens of the laser beam irradiation unit 50 with the position on the back surface 8 where the mark 13 defined in the processing conditions is to be formed based on the position of the detected planned division lines 6 in the Z-axis direction.

[0052] In the first embodiment, in the mark forming step 1002, the control unit 100 of the processing device 30 controls the X-axis moving unit 61 to move the holding table 42 in the X-axis direction, while irradiating the laser beam from the laser beam irradiation unit 50 toward a position on the back surface 8 where the mark 13 defined in the processing conditions is to be formed. Then, the metal layer 9 at the position on the back surface 8 of the wafer 1 where the laser beam is irradiated is subjected to an ablation process, and the mark 13, which is a groove, is formed. Thus, in the first embodiment, in the mark forming step 1002, the processing device 30 forms the mark 13 based on the planned division line 6 imaged and detected by the lower imaging unit 80.

[0053] In the first embodiment, in the mark forming step 1002, the processing device 30 forms marks 13 in the peripheral excess area 5 on the back surface 8 of the wafer 1 and on the extensions of the centers in the width direction of the dividing lines 6, as shown in Fig. 5. Also, in the first embodiment, in the mark forming step 1002, the processing device 30 forms marks 13 on the extensions of the centers in the width direction of the dividing lines 6 for every predetermined number of the dividing lines 6. Also, in the present invention, in the mark forming step 1002, the processing device 30 may form marks 13 on the extensions of the centers in the width direction of all the dividing lines 6 in the peripheral excess area 5 on the back surface 8 of the wafer 1.

[0054] Also, in the present invention, in the mark forming step 1002, the processing device 30 may form a cross-shaped mark 13 at an intersection between the planned dividing lines 6 in the device region 4 on the back surface 8 of the wafer 1, as shown in Fig. 6. Thus, in the present invention, in the mark forming step 1002, the mark 13 may be formed in a cross shape at a position corresponding to the intersection between the planned dividing lines 6.

[0055] Furthermore, in the present invention, in the mark formation step 1002, marks 13 are formed on the extensions of the widthwise center of every predetermined number of the planned division lines 6 within the peripheral excess area 5 on the back surface 8 of the wafer 1, or at positions corresponding to the intersections of the planned division lines 6, so that the marks 13 are formed at positions corresponding to the planned division lines 6 and in the areas to be removed in the dicing step 1003.

[0056] (Dicing step) Fig. 7 is a perspective view that shows a schematic diagram of a dicing step of the wafer processing method shown in Fig. 2. The dicing step 1003 is a step of dicing the wafer 1 from the back surface 8 side based on the marks 13 formed in the mark forming step 1002, and dividing the wafer 1 into individual chips 10.

[0057] 7 suction-holds the front surface 3 side of the wafer 1 on a holding surface of a holding table (not shown) via the tape 11, and clamps the frame 12 with clamps (not shown) around the holding table. In the first embodiment, in the dicing step 1003, the cutting device 90 captures an image of the back surface 8 side of the wafer 1 held on the holding surface of the holding table with an imaging unit (not shown) and detects the mark 13 from the captured image.

[0058] In the first embodiment, in the dicing step 1003, the cutting device 90 performs alignment to align the cutting blade 92 of the cutting unit 91 with the division lines 6 of the wafer 1 based on the position of the detected mark 13, the interval between the division lines 6, and the like. In the first embodiment, in the dicing step 1003, the cutting device 90 cuts the cutting blade 92, which rotates around its axis, into the division lines 6 of the wafer 1 until it reaches the tape 11 while relatively moving the cutting blade 92 of the cutting unit 91 and the wafer 1 along the division lines 6, as shown in FIG. 7, to cut the wafer 1 along the division lines 6 and divide the wafer 1 into individual chips 10.

[0059] In the dicing step 1003 of the first embodiment, when the cutting device 90 cuts all the planned dividing lines 6 of the wafer 1, it retreats the cutting unit 91 from the wafer 1 and moves the holding table to the carry-in / out area. In the dicing step 1003 of the first embodiment, the cutting device 90 stops the suction holding of the holding table positioned in the carry-in / out area and releases the clamping of the frame 12 of the clamping unit, thereby completing the processing operation, i.e., the dicing step 1003.

[0060] In the wafer processing method according to the first embodiment described above, marks 13 indicating the intended division lines 6 are formed in the metal layer 9 laminated on the rear surface 8 of the wafer 1 before the dicing step 1003 .

[0061] For this reason, in the wafer processing method of embodiment 1, the front surface 3 side of the wafer 1 is attached to tape 11 to prevent foreign matter from adhering to the device 7, and the position of the planned division line 6 can be identified even if a metal layer 9 is formed on the back surface 8 side of the wafer 1.

[0062] As a result, the wafer processing method according to embodiment 1 can easily cut the intended division lines 6 even in the case of a wafer 1 in which the front surface 3 side of the wafer 1 is attached to tape 11 to prevent foreign matter from adhering to the device 7 and a metal layer is laminated on the back surface 8 side.

[0063] It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. [Explanation of symbols]

[0064] 1 wafer 3 surface 6. Planned division line 7 Devices 8 Back side 9 metal layer 10 Chips 13 Mark 42 Holding Table 441 Holding surface 1002 Mark formation step 1003 Dicing Step

Claims

1. A method for processing a wafer having a front surface side with a plurality of intersecting division lines and a plurality of devices formed in each area partitioned by the division lines, and a metal layer laminated on a back surface side, comprising the steps of: a mark forming step of forming marks on the back surface of the wafer, the marks indicating the positions of the planned dividing lines; a dicing step of dicing the wafer from the back surface side thereof using the marks formed in the mark forming step as a reference to divide the wafer into individual chips.

2. In the mark forming step, holding the front surface side of the wafer with a holding table including a holding surface at least a portion of which is made of a transparent material; 2. The wafer processing method according to claim 1, further comprising the steps of: detecting the dividing lines by imaging the front surface side of the wafer through the holding surface; and forming the marks based on the detected dividing lines.

3. 2. The wafer processing method according to claim 1, wherein the marks are formed in areas that correspond to the intended dividing lines and are to be removed in the dicing step.

4. 4. The wafer processing method according to claim 3, wherein the mark is formed in a cross shape, and is formed in an area that corresponds to an intersection of the intended dividing lines and is to be removed in the dicing step.

5. 5. The wafer processing method according to claim 1, wherein the wafer is made of SiC.

Images