Wafer processing device

Abstract

To provide a wafer processing device capable of precisely controlling the cutting depth when removing a chamfered part.SOLUTION: A cutting device 1 comprises height measurement means 11 which measures the upper surface height of a wafer 20 suction-held on a chuck table 7, and control means 100. The control means 100 includes: a cutting depth storage unit which stores a target cutting depth in a Z-axis direction of a chamfered part 26c to be removed from a surface of a wafer 20 that is suction-held on the chuck table 7; a surface coordinate storage unit which operates the height measurement means 11 to measure and store Z-axis coordinates of the surface of the wafer 20; and a chamfered part removal operation unit which operates Z-axis feeding means on the basis of the target cutting depth stored in the cutting depth storage unit and the Z-axis coordinates stored in the surface coordinate storage unit to move cutting means 8 in the Z-axis direction for cutting to remove the chamfered part 26c.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus for processing a wafer having a peripheral excess area formed on its surface, the peripheral excess area including a device area in which a plurality of devices are partitioned by planned division lines and a chamfered portion surrounding the device area. [Background technology]

[0002] A wafer has a plurality of devices such as ICs and LSIs formed on its front surface, which are divided along planned dividing lines. The back surface is ground to a specified thickness, and then the wafer is divided into individual device chips by a cutting machine for use in electrical equipment such as mobile phones and personal computers.

[0003] The grinding device includes a chuck table for holding a wafer, a grinding means having a rotatable grinding wheel with grinding stones arranged in a ring shape for grinding the wafer held on the chuck table, a feeding means for feeding the grinding means for grinding, and a measuring means for measuring the thickness of the wafer, and can grind the back surface of the wafer to the desired thickness.

[0004] However, because a chamfer is formed on the outer periphery of the wafer, when the back surface of the wafer is ground to thin it, the chamfer on the outer periphery of the wafer becomes a sharp knife edge, which causes cracks to form from the outer periphery and progress into the device region, damaging the device and posing a risk of injury to the operator.

[0005] Therefore, the applicant has proposed a technique for removing the chamfered portion formed on the outer circumferential edge before grinding the back surface of the wafer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-96295 A Summary of the Invention [Problem to be solved by the invention]

[0007] In particular, in the case of a two-layer wafer in which two wafers are stacked, before stacking the wafers, the chamfered portion on the outer periphery of one of the wafers whose back surface is ground is removed by a cutting blade, and then the front surface of one of the wafers from which the chamfered portion has been removed is stacked on the other wafer. In this case, if the entire chamfered portion of one of the wafers is removed, it is not possible to align the wafers based on the shape of the outer periphery, and it is difficult to perform accurate alignment when stacking the wafers, so it is necessary to leave more than half of the chamfered portion of one of the wafers. Furthermore, when removing the chamfered portion with a cutting blade, it is also necessary to remove the chamfered portion by grinding the back surface of one of the wafers with a cutting depth slightly exceeding the finished thickness, so it is required to remove the chamfered portion with high precision.

[0008] However, there is a problem in that it becomes difficult to precisely remove the chamfered portion on the outer periphery of the wafer to the desired cutting depth due to wear of the cutting blade and distortion caused by heat generated by the cutting blade during cutting.

[0009] The present invention has been made in consideration of the above-mentioned facts, and its main technical object is to provide a wafer processing device that can control the cutting depth when removing a chamfered portion with high precision, even if the cutting blade is worn or distorted due to heat generation of the cutting blade. [Means for solving the problem]

[0010] In order to solve the above-mentioned main technical problem, according to the present invention, there is provided a processing apparatus for a wafer having a surface formed with a device area in which a plurality of devices are partitioned by planned division lines, and an outer peripheral excess area having a chamfered portion surrounding the device area, the apparatus comprising: a holding surface defined by an X-axis and a Y-axis for suction-holding a wafer, a rotatable chuck table; cutting means for rotatably supporting a cutting blade for removing the chamfered portion of the wafer held by suction on the chuck table and having a rotation axis in the Y-axis direction; positioning means for positioning the cutting means so that the extension direction of the rotation axis passes through the rotation center of the chuck table; and a Z-axis feed means for processing and feeding the cutting means in the Z-axis direction perpendicular to the holding surface. There is provided a wafer processing apparatus including: a feeding means; a height measuring means for measuring the height of an upper surface of a wafer held by suction on the chuck table; and a control means, wherein the control means includes a cutting depth memory unit for storing a target cutting depth in the Z-axis direction of a chamfer to be removed from the surface of the wafer held by suction on the chuck table; a surface coordinate memory unit for operating the height measuring means to measure and store the Z-axis coordinate of the surface of the wafer; and a chamfer removal operation unit for operating the Z-axis feeding means based on the target cutting depth stored in the cutting depth memory unit and the Z-axis coordinate stored in the surface coordinate memory unit to feed the cutting means in the Z-axis direction to remove the chamfer.

[0011] The control means preferably includes a removal surface height storage unit that operates the height measurement means after the chamfer removing unit removes the chamfer from the outer periphery of the wafer to measure and store the Z-axis coordinate of the removal surface of the outer periphery of the wafer after the chamfer is removed, and a correction unit that calculates an actual cutting depth based on the difference between the Z-axis coordinate of the wafer surface stored in the surface coordinate storage unit and the Z-axis coordinate of the removal surface stored in the removal surface height storage unit, and if the actual cutting depth matches the target cutting depth stored in the cutting depth storage unit, maintains the target cutting depth, and if they do not match, calculates the difference between the target cutting depth and the actual cutting depth to set it as a correction value for the cutting depth, and preferably adds the correction value to the target cutting depth in the chamfer removing unit to operate the Z-axis feed means and feed the cutting means in the Z-axis direction. Also, the control means preferably operates the correction unit periodically to update the correction value. Effect of the Invention

[0012] The wafer processing apparatus of the present invention includes a rotatable chuck table having a holding surface defined by an X-axis and a Y-axis for suction-holding a wafer, cutting means for rotatably supporting a cutting blade for removing a chamfered portion of a wafer held on the chuck table and having a rotation axis in the Y-axis direction, positioning means for positioning the cutting means so that the extension direction of the rotation axis passes through the rotation center of the chuck table, Z-axis feeding means for processing and feeding the cutting means in the Z-axis direction perpendicular to the holding surface, height measuring means for measuring the height of an upper surface of a wafer held on the chuck table by suction, and control means, and the control means is configured to control the chuck table. Since the system is configured to include a cutting depth memory unit which stores a target cutting depth in the Z-axis direction of the chamfer to be removed from the front surface of the wafer held by suction, a surface coordinate memory unit which operates the height measuring means to measure and store the Z-axis coordinate of the front surface of the wafer, and a chamfer removal operation unit which operates the Z-axis feed means based on the target cutting depth stored in the cutting depth memory unit and the Z-axis coordinate stored in the surface coordinate memory unit, and feeds the cutting means in the Z-axis direction to remove the chamfer, it becomes possible to accurately cut the chamfer from the front surface of the wafer to a thickness slightly exceeding the finished thickness obtained by grinding the back surface of the wafer. [Brief description of the drawings]

[0013] [Figure 1] 1 is an overall perspective view of a cutting device according to an embodiment of the present invention; [Diagram 2] 2 is a conceptual diagram showing a configuration of a control means disposed in the cutting device shown in FIG. 1. [Diagram 3] FIG. 2 is a perspective view showing a manner in which a wafer is placed on a chuck table of a cutting machine. [Figure 4] FIG. 2 is a perspective view showing a mode in which the height of the surface of the wafer is measured by a height measuring means. [Diagram 5] 5 is a side view showing a mode of measuring the height of the surface of the wafer by the measuring means shown in FIG. 4. [Figure 6] 1 is a perspective view showing a mode of positioning a cutting means on the outer periphery of a wafer held on a chuck table. FIG. [Figure 7]FIG. 2 is a perspective view showing an aspect of cutting for removing a chamfered portion of a wafer. [Figure 8] 8(a) is an enlarged side view of a part of the cutting process shown in FIG. 7, and FIG. 8(b) is a side view showing an aspect in which a removed surface is formed by removing the chamfered portion through the cutting process shown in (a). [Figure 9] 9 is a side view showing a manner of measuring the height of the removed surface on the outer periphery of the wafer shown in FIG. 8. FIG. [Figure 10] 3 is a flowchart of a control program executed by a correction unit of the control means shown in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a wafer processing apparatus constructed based on the present invention will be described in detail with reference to the accompanying drawings.

[0015] 1 shows a cutting device 1, which is an example of the wafer processing device of the present invention. The cutting device 1 includes a housing 2 having a substantially rectangular parallelepiped shape, a cassette 4 (shown by a two-dot chain line) placed on a cassette table 4a of the housing 2, a carry-in / out means 3 for carrying out a wafer 20 from the cassette 4 to a temporary placement table 5, a transport means 6 having a rotating arm for transporting the wafer 20 carried out to the temporary placement table 5 to a chuck table 7, a cutting means 8 to which a cutting blade 9 for processing the wafer 20 held on the chuck table 7 is rotatably attached, and an imaging device for imaging the wafer 20 held on the chuck table 7 and detecting the wafer 20 by the cutting means. 8, alignment means 10 for detecting the region to be machined, height detection means 11 arranged adjacent to the alignment means 10 in the Y-axis direction and for detecting the height of the upper surface of the wafer 20 held on the chuck table 7, cleaning and unloading means 13 for transporting the wafer 20 from the loading / unloading position where the chuck table 7 is positioned in Fig. 1 to the cleaning device 12, display means 14 constituting a touch panel arranged on the upper part of the housing 2, input means 15, and control means 100 for controlling each operating part of the cutting device 1. Note that although the control means 100 is shown outside the housing 2 for convenience of explanation, it is actually accommodated inside the housing 2.

[0016] The chuck table 7 is configured to be rotatable and includes an adsorption chuck 71 formed of an air-permeable porous member and constituting a holding surface defined by an X-axis indicated by an arrow X in the figure and a Y-axis indicated by an arrow Y perpendicular to the X-axis, and a frame 72 surrounding the adsorption chuck 71, and is connected to suction means (not shown) via the frame 72. By operating the suction means, a negative pressure is generated on the upper surface of the adsorption chuck 71, so that the wafer 20 can be sucked and held.

[0017] The cutting means 8 includes a rotating shaft 83 extending in the Y-axis direction and rotatably supporting a cutting blade 9 for removing the chamfered portion 26c formed on the outer peripheral end of the wafer 20 held by suction on the above-mentioned chuck table 7, and includes a rotating shaft housing 82 for rotatably supporting the rotating shaft 83, and a blade cover 81 for covering the cutting blade 9 arranged at the tip of the rotating shaft housing 82.

[0018] Inside the housing 2, there are disposed an X-axis feed means for feeding the chuck table 7 in the X-axis direction for processing, a Y-axis feed means for indexing and feeding the cutting means 8 in the Y-axis direction perpendicular to the X-axis direction, a Z-axis feed means for moving and feeding the cutting means 8 in the Z-axis direction (vertical direction) perpendicular to the suction chuck 71 forming the holding surface of the chuck table 7, which is perpendicular to the X-axis and Y-axis directions, and a rotary drive means for rotating the chuck table 7 (none of which are shown). The X-axis feed means, Y-axis feed means, Z-axis feed means, and rotary drive means described above are controlled by a control means 100. The X-axis feed means in this embodiment functions as a positioning means for positioning the extension direction of the rotation axis 83 of the cutting means 8 so as to pass through the rotation center of the chuck table 7.

[0019] The control means 100 is configured by a computer, and includes a central processing unit (CPU) that performs calculations according to a control program, a read-only memory (ROM) that stores the control program, etc., a readable / writable random access memory (RAM) for temporarily storing detected values, calculation results, etc., an input interface, and an output interface (details are not shown in the drawings). The control means 100 is connected to each operating unit of the cutting device 1, as well as to the above-mentioned display means 14 and input means 15, and an operator can operate the display means 14 and input means 15 to instruct the start and end of processing, input processing conditions, etc.

[0020] 2, the control means 100 includes a cutting depth storage unit 110 for storing a target cutting depth DZ in the Z-axis direction of the chamfered portion to be removed from the front surface of the wafer 20 held by suction on the chuck table 7, a surface coordinate storage unit 120 for operating the height measurement means 11 to measure and store the Z-axis coordinate Z1 of the front surface of the wafer 20, and a chamfered portion removing operation unit 130 for sending an operation signal to the Z-axis feed means described above based on the target cutting depth DZ stored in the cutting depth storage unit 110 and the Z-axis coordinate Z1 stored in the surface coordinate storage unit 120 to feed the cutting means 8 in the Z-axis direction to remove the chamfered portion 26c of the wafer 20. In the chamfered portion removing operation unit 130 shown in the figure, the Z-axis feed means is controlled by adding a correction value ΔZ, which will be described later, to the target cutting depth DZ, but in the initial state when the cutting blade 9 is new, the correction value ΔZ is 0.

[0021] Furthermore, the control means 100 of this embodiment is equipped with a removal surface height memory unit 140 that operates the cutting means 8 by the chamfer removal operation unit 130 to remove the chamfered portion 26c of the wafer 20, and then operates the height measurement means 11 to measure and store the height (Z-axis coordinate Z2) of the removed surface of the chamfered portion 26c of the wafer 20 after the chamfered portion 26c has been removed, and a correction unit 150 that calculates an actual cutting depth SZ based on the difference between the Z-axis coordinate Z1 of the surface stored in the surface coordinate memory unit 120 and the Z-axis coordinate Z2 stored in the removal surface height memory unit 140, and if the actual cutting depth SZ matches the target cutting depth DZ stored in the cutting depth memory unit 110, maintains the target cutting depth DZ, and if they do not match, calculates the difference ΔZ between the target cutting depth DZ when the chamfered portion 26c is removed and the actual cutting depth SZ, and sets the calculated difference ΔZ as a correction value for the cutting depth.

[0022] The cutting device 1 of this embodiment has substantially the configuration as described above, and the functions and effects of the cutting device 1, particularly the control means 100, will be described below.

[0023] FIG. 3 shows a wafer 20 before being processed in this embodiment. The illustrated wafer 20 is a semiconductor (e.g., silicon) wafer having a diameter of 300 mm and a thickness of 700 μm, with a plurality of devices 22 formed on the surface 20a partitioned by the division lines 24, and a plurality of wafers are stored in a cassette 4. As shown in the figure, the wafer 20 includes a device region 26a in which the devices 22 are formed, a peripheral surplus region 26b surrounding the device region 26a, and a chamfered portion 26c in which the peripheral end of the peripheral surplus region 26b is chamfered. In FIG. 3, a ring-shaped virtual line 28 (shown by a broken line) is shown dividing the device region 26a and the peripheral surplus region 26b, but this virtual line 28 is added for convenience of explanation and is not actually formed on the surface 20a of the wafer 20. The length L of the chamfered portion 26c of the wafer 20 in the radial direction from the outer circumferential end to be removed is 3.0 mm, and is stored in advance in the control means 100. In addition, a target cutting depth DZ (e.g., 300 μm) in the Z-axis direction of the chamfered portion 26c to be removed from the front surface 20a of the wafer 20 held by suction on the chuck table 7 is input in advance by an operator using the display means 14 or input means 15 described above, and is stored in the cutting depth storage unit 110.

[0024] In this embodiment, as described above, the radial length L from the outer peripheral end to be removed in the chamfered portion 26c is 3.0 mm, while the width (thickness) of the cutting blade 9 is 3.3 mm, which is larger than the radial length L from the outer peripheral end to be removed. The cutting blade 9 is, for example, made by solidifying and sintering diamond abrasive grains with a bond material, and the bond material is preferably selected from, for example, a resin bond, a bidrified bond, and a metal bond.

[0025] When performing processing to remove the chamfered portion 26c of the wafer 20 shown in Fig. 3 by the cutting device 1 shown in Fig. 1, the wafer 20 is carried out from the cassette 4 of the cutting device 1 described based on Fig. 1 by the carry-in / out means 3 and temporarily placed on the temporary placement table 5, and the conveying means 6 is operated to suck the wafer 20 from the temporary placement table 5, and conveys and places it on the chuck table 7. At this time, the wafer 20 is placed on the chuck table 7 with the back surface 20b facing downward as shown in Fig. 3, and a suction means (not shown) is operated to generate a negative pressure in the suction chuck 71 to hold the wafer by suction.

[0026] As described above, when the wafer 20 is held by suction on the chuck table 7, the X-axis feed means is operated to position the wafer 20 together with the chuck table 7 directly under the alignment means 10, an image of the wafer 20 is taken, and alignment is performed to detect the center of the wafer 20 and the position of an area having a radial length L (3.0 mm) from the outer peripheral end of the chamfered portion 26c to be removed in the outer peripheral excess area 26b, and the position information is stored in a predetermined storage unit of the control means 100. Furthermore, the X-axis feed means is operated to position the height detection means 11 on the surface 20a of the area of ​​the chamfered portion 26c to be removed of the wafer 20, as shown in Figures 4 and 5, and a Z-axis coordinate Z1 indicating the height of the surface 20a based on the surface height Z0 of the chuck table 7 (measured in advance and stored in the control means 100) serving as a reference is measured, and stored in the surface coordinate storage unit 120 of the control means 100. The difference between the surface height Z0 of the chuck table 7 and the Z-axis coordinate Z1 of the surface 20a in the region of the chamfered portion 26c is the thickness of the wafer 20.

[0027] Next, based on the position information of the processing area detected by the above-mentioned alignment, the X-axis feed means of the above-mentioned cutting device 1 is operated to position the cutting means 8 so that the extension direction of the rotation axis 83 of the cutting means 8 passes through the rotation center of the chuck table 7 (which is also the center of the wafer 20) as shown in Fig. 6. Then, the above-mentioned Y-axis feed means is operated to position the area to be removed of the chamfered portion 26c of the wafer 20 directly below the cutting blade 9 attached to the cutting means 8. At this time, the cutting blade 9 is positioned at a position that coincides with the radial length L (3.0 mm) from the outer circumferential end of the chamfered portion 26c to be removed.

[0028] Then, the cutting blade 9 is rotated in the direction indicated by the arrow R1 at a predetermined rotational speed (e.g., 30,000 rpm), and the chamfer removal operation unit 130 is executed based on the target cutting depth DZ stored in the cutting depth memory unit 110 and the Z-axis coordinate Z1 of the surface 20a in the area of ​​the chamfered portion 26c stored in the surface coordinate memory unit 120, and the Z-axis feed means described above is operated to lower the cutting means 8 in the direction indicated by the arrow R2 in Figure 6, and the cutting blade 9 is fed for processing toward the chamfered portion 26c of the wafer 20.

[0029] As shown in Fig. 7, together with the above-mentioned machining feed of the cutting blade 9, the chuck table 7 is rotated at least once in the direction indicated by the arrow R3 at a predetermined rotation speed (for example, 0.8 to 3 rpm). At this time, the cutting blade 9 is operated according to the target cutting depth DZ (300 µm) in the region of the radial length L (3.0 mm) from the outer peripheral end as shown in Fig. 8(a). As a result, as shown in Fig. 8(b), the chamfered portion 26c formed at the outer peripheral end of the outer peripheral excess region 26b of the wafer 20 is removed in an annular shape to form a chamfer-removed portion 26d. The above target cutting depth DZ is set according to the thickness of the wafer 20 that will be finished by grinding from the back surface 20b side in the back surface grinding process (details will be omitted) performed in a subsequent process. In this embodiment, since the back surface 20b of the wafer 20 will be ground to a thickness of 250 μm in the back surface grinding process performed later, the target cutting depth DZ for removing the chamfered portion is set to 300 μm.

[0030] In the embodiment described above, the chamfer removal operation unit 130 is executed based on the target cutting depth DZ stored in the cutting depth memory unit 110 and the Z-axis coordinate Z1 of the front surface 20a of the area of ​​the chamfered portion 26c stored in the front surface coordinate memory unit 120, so that it is possible to accurately cut the chamfered portion 26c from the front surface 20a of the wafer 20 to a thickness that slightly exceeds the finished thickness obtained by grinding the back surface of the wafer 20.

[0031] In the above embodiment, the cutting blade 9 attached to the cutting means 8 is prepared to have a thickness of 3.3 mm, which is larger than the radial length L (3.0 mm) from the outer peripheral end to be removed, but the present invention is not limited to this, and a cutting blade having a thickness of less than 3.0 mm may be used. In this case, by performing cutting while changing the cutting position in multiple steps according to the thickness of the cutting blade 9, the chamfered portion 26c forming the outer peripheral end of the outer peripheral excess region 26b of the wafer 20 can be removed in a ring shape with a width of the radial length L, as described above.

[0032] In the cutting device 1 of the present embodiment, since the above-described removed surface height storage unit 140 and the correction unit 150 are provided, the processing accuracy when removing the chamfered portion 26c can be further improved.

[0033] As described above, after the chamfered portion 26c forming the outer peripheral end of the outer peripheral excess region 26b of the wafer 20 has been removed in an annular shape with a width of the radial length L from the outer peripheral end in accordance with the target cutting depth DZ, the X-axis feed means described above is operated to move the wafer 20, and the chamfer-removed portion 26d after the chamfered portion 26c has been removed is positioned directly below the height measurement means 11, as shown in Fig. 9. Next, the height measurement means 11 is operated to measure the Z-axis coordinate Z2 of the removal surface 26e, which is the upper surface of the chamfer-removed portion 26d, and the Z-axis coordinate Z2 is stored in the removal surface height storage unit 140.

[0034] As described above, after the Z-axis coordinate Z2 of removal surface 26e is measured and stored in removal surface height storage unit 140, a control program shown in the flowchart of Fig. 10 executed by correction unit 150 is executed to calculate a correction value ΔZ for the cut depth. The procedure for calculating the correction value ΔZ for the cut depth will be described below with reference to Fig. 10.

[0035] First, when the control program shown in the flowchart of FIG. 10 is started (START), the actual cutting depth SZ is calculated from the difference between the Z-axis coordinate Z1 of the surface of the wafer 20 stored in the surface coordinate memory unit 120 and the Z-axis coordinate Z2 of the removal surface 26e (step S1).

[0036] Next, proceed to step S2, and judge whether the actual cutting depth SZ matches the above-mentioned target cutting depth DZ (step S2). The judgment of whether the actual cutting depth SZ matches the target cutting depth DZ is not limited to judging whether they match completely, and it is preferable to judge with a certain margin. For example, when performing step S2, DZ-SZ=ΔZ is calculated, and the judgment condition of whether the actual cutting depth SZ matches the target cutting depth DZ can be whether the value of ΔZ is equal to or less than a predetermined value. The predetermined value can be set to, for example, 20 μm. If the value of ΔZ is equal to or less than 20 μm, the cutting depth is machined at approximately the desired cutting depth, and the cutting depth exceeding the finished thickness formed by the grinding process performed in the subsequent process is ensured. Therefore, if the answer is yes in step S2, proceed to step S3, and without using ΔZ as a correction value, the cutting depth when the cutting blade 9 is cut in by the chamfer removal operation unit 130 is maintained at the target cutting depth DZ, and the flowchart ends (END).

[0037] On the other hand, if the result of the determination in step S2 is no, the process proceeds to step S4. It is assumed that the actual cutting depth SZ and the target cutting depth DZ do not match, and the result of the determination in step S2 is no, due to the cutting blade 9 being worn or due to the cutting blade 9 being distorted due to heat generation during cutting, but the present invention is not limited to this.

[0038] In step S4, ΔZ obtained by calculating the difference (DZ-SZ) between the target cutting depth DZ and the actual cutting depth SZ is used as the correction value. If DZ-SZ=ΔZ has already been calculated in step S2, the ΔZ calculated in step S2 can be used as the correction value as is. If the correction value ΔZ has already been calculated and stored in the control means 100 before executing this flowchart, the ΔZ obtained by executing this flowchart is updated as the new correction value ΔZ.

[0039] As described above, after performing step S4, the process proceeds to step S5, where the above-mentioned correction value ΔZ is transmitted to the chamfer removing operation unit 130, and the flow chart is ended (END). As shown in FIG. 2, when the correction value ΔZ calculated by the correction unit 150 is transmitted to the chamfer removing operation unit 130, the cutting depth of the next cutting process performed by the operation of the chamfer removing operation unit 130 becomes the target cutting depth DZ+correction value ΔZ based on the Z-axis coordinate Z1 stored in the surface coordinate storage unit 120, and the cutting depth is corrected based on the correction value ΔZ. Note that, for the wafer 20 that caused the need for correction of the cutting depth, since the cutting was not actually performed at the target cutting depth DZ, it is desirable to perform cutting again to remove the chamfer 26c based on the cutting depth (DZ+ΔZ) to which the correction value ΔZ is added. In addition, when the cutting process for removing the chamfered portion 26c of the wafer 20 is performed based on the above-mentioned cutting depth DZ+correction value ΔZ, it is preferable to execute the control program shown in the flowchart of Fig. 10 to confirm the difference between the actual cutting depth SZ and the target cutting depth DZ. As described above, after the target cutting depth DZ is corrected by the correction value ΔZ and the chamfered portion 26c of the wafer 20 held on the chuck table 7 is removed, the wafer 20 on the chuck table 7 is carried out by the cleaning and carrying out means 13 and transported to the cleaning device 12, where the wafer 20 is cleaned and dried, and the transport means 6 and the carry-in / out means 3 are operated to store the wafer 20 in a predetermined position in the cassette 4.

[0040] The above-mentioned update of the correction value ΔZ performed by operating the correction unit 150 can be performed at any timing, but is preferably performed periodically. The periodic update may be performed, for example, every time the processing of one wafer 20 is completed, every time all the wafers 20 contained in one cassette 4 are completed, or every time the processing of one day is completed, as described above.

[0041] As described above, the target cutting depth DZ of the cutting process performed by the chamfer removal operation unit 130 is corrected by the above-mentioned correction value ΔZ, so that the chamfer 26c of the wafer 20 can be removed with high precision to form the chamfer removed portion 26d, even if there are influences such as wear of the cutting blade 9 and distortion due to heat. [Explanation of symbols]

[0042] 1:Cutting device 2: Housing 3: Carrying in / out means 4: Cassette 5: Temporary table 6: Means of transportation 7: Chuck table 8: Cutting means 81: Blade cover 82: Rotating shaft housing 83: Rotation axis 9: Cutting blade 10: Alignment means 11: Height measurement means 12: Cleaning equipment 13: Cleaning and carrying out means 14:Display means 15: Input method 20: Wafer 20a: Surface 20b: Back side 22: Device 24: Planned division line 26a: Device area 26b: Surplus outer area 26c: Chamfered part 26d: Chamfer removal section 26e: Removal surface 28: Virtual line 100: Control means 110: Cutting depth memory section 120: Surface coordinate storage unit 130: Chamfer removal operation unit 140: Removal surface height memory unit 150: Correction section DZ: Target cutting depth SZ: Actual cutting depth

Claims

1. A processing apparatus for a wafer having a peripheral excess area formed on a surface thereof, the peripheral excess area including a device area in which a plurality of devices are partitioned by a division line and a chamfered portion surrounding the device area, comprising: the wafer holding apparatus includes a rotatable chuck table having a holding surface defined by an X-axis and a Y-axis for holding a wafer by suction; cutting means for rotatably supporting a cutting blade for removing a chamfered portion of the wafer held by suction on the chuck table and having a rotation axis in the Y-axis direction; positioning means for positioning the cutting means so that the extension direction of the rotation axis passes through the rotation center of the chuck table; Z-axis feeding means for feeding the cutting means for processing in the Z-axis direction perpendicular to the holding surface; height measuring means for measuring the height of an upper surface of the wafer held by suction on the chuck table; and control means, The control means a cutting depth storage unit that stores a target cutting depth in a Z-axis direction of a chamfered portion to be removed from the front surface of the wafer held by suction on the chuck table; a surface coordinate storage unit that operates the height measuring means to measure and store the Z-axis coordinate of the surface of the wafer; and a chamfer removal operation unit that operates the Z-axis feed means based on the target cut depth stored in the cut depth memory unit and the Z-axis coordinates stored in the surface coordinate memory unit, and feeds the cutting means in the Z-axis direction to remove the chamfer.

2. the control means includes a removed surface height storage unit that operates the height measurement means after the chamfer removing operation unit removes the chamfer from the outer periphery of the wafer to measure and store the Z-axis coordinate of the removed surface on the outer periphery of the wafer after the chamfer is removed; a correction unit that calculates an actual cutting depth based on a difference between a Z-axis coordinate of the surface of the wafer stored in the surface coordinate storage unit and a Z-axis coordinate of the removal surface stored in the removal surface height storage unit, and if the actual cutting depth matches the target cutting depth stored in the cutting depth storage unit, maintains the target cutting depth, and if they do not match, calculates a difference between the target cutting depth and the actual cutting depth to set the difference as a cutting depth correction value, 2. The wafer processing apparatus according to claim 1, wherein the Z-axis feed means is actuated by adding the correction value to a target cutting depth in the chamfer removing operation portion, thereby feeding the cutting means in the Z-axis direction.

3. The control means 3. The wafer processing apparatus according to claim 2, wherein the correction unit is operated periodically to update the correction value.

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