Wafer manufacturing method and grinding device

Abstract

To manufacture a wafer having a predetermined thickness from works even when a work having a residual peeling layer and a work having no residual peeling layer are mixed.SOLUTION: Even when a work is a normal work 800 having a first residual peel layer 900 on one side, and even when the work is an adjustment work 700 not having a first residual peeling layer 900, both sides of the work are ground to produce a wafer with a predetermined thickness. That is, in the present embodiment, since both sides of the work are ground, wafers can be manufactured from two types of works regardless of whether the first residual peeling layer 900 is present on one side. Therefore, even when two kinds of works are mixed in a first cassette 112, wafers with a predetermined thickness can be easily manufactured from these works.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a wafer manufacturing method and a grinding apparatus. [Background technology]

[0002] In the technology disclosed in Patent Document 1, a laser beam having a wavelength that is transparent to SiC is irradiated onto the top surface of a cylindrical SiC ingot, and the focal point, which is focused at a predetermined depth, is moved parallel to the top surface. This forms a peeling layer that includes a modified layer and cracks extending from the modified layer, and a disk-shaped workpiece is peeled off from the peeling layer. Wafers are produced from the ingot by grinding this workpiece.

[0003] When manufacturing wafers using this technology, once multiple workpieces have been obtained from an ingot, a new ingot is irradiated with a laser beam to obtain a new workpiece. In this case, if the output of the laser beam irradiated onto the new ingot is the same as the output of the laser beam irradiated onto the previous ingot, the peeled layer may become thinner or thicker.

[0004] If the peeling layer is thin, it becomes difficult to peel the workpiece because adjacent cracks are not connected when viewed from the top surface of the ingot. On the other hand, if the peeling layer is thick, the workpiece obtained by peeling will be thin, and the number of workpieces that can be obtained from the ingot will be reduced.

[0005] To solve this problem, the output of the laser beam is adjusted so that the peeled layer has a predetermined thickness. In other words, the thickness of the peeled layer is measured every time the ingot is changed.

[0006] In measuring the thickness of this peeling layer, a peeling layer is formed on an ingot, and the workpiece is peeled from the peeling layer. The peeling layer remaining on the peeling surface of the ingot is then ground and removed, and the peeling layer remaining on the peeling surface of the workpiece is also ground and removed. The thickness of the ingot after the peeling layer has been removed and the thickness of the workpiece after the peeling layer have been removed are subtracted from the thickness (length) of the ingot before the peeling layer was formed. This yields the thickness of the peeling layer. The output of the laser beam is then adjusted so that the thickness of the peeling layer thus determined falls within a predetermined range (tolerance). In other words, the following steps are repeated until the thickness of the peeling layer falls within the predetermined range: forming the peeling layer, peeling the workpiece from the ingot, removing the peeling layer from the ingot and the workpiece, measuring the thickness of the peeling layer, and adjusting the output of the laser beam.

[0007] Once the laser beam output adjustment is complete, the process of forming a peeling layer, peeling the workpiece from the ingot, and removing the peeling layer remaining on the top surface of the ingot is repeated. The resulting workpiece, with the peeling layer still attached, is placed in a cassette. The cassette is then placed on a cassette stage of a grinding device equipped with two grinding mechanisms. One grinding mechanism removes the peeling layer from the workpiece, and the other grinding mechanism removes grinding marks on both sides of the workpiece and grinds the workpiece to a uniform thickness. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-111143 Summary of the Invention [Problem to be solved by the invention]

[0009] The thickness and surface condition of the workpiece from which the peeled layer obtained during laser beam output adjustment has been removed differs from that of the workpiece obtained after laser beam output adjustment has been completed, with the peeled layer remaining. For this reason, these workpieces have traditionally been ground separately to produce wafers. As a result, it takes a long time to grind all of the workpieces that can be extracted from the ingot into wafers.

[0010] Therefore, the object of the present invention is to grind workpieces having a peeling layer and workpieces having no peeling layer even if they are mixed in a cassette, and to produce wafers of a predetermined thickness. [Means for solving the problem]

[0011] The wafer manufacturing method of the present invention (this manufacturing method) is a wafer manufacturing method in which a laser beam that is transparent to the ingot is irradiated from one side of the ingot, the focal point focused at a predetermined depth is moved parallel to the one side to form a peeling layer, and the plate-shaped workpiece obtained by peeling from the peeling layer is ground with a grinding wheel to manufacture a wafer.The method includes an output adjustment step of forming an adjustment peeling layer on the ingot and removing a first remaining peeling layer, which is the peeling layer remaining on the adjustment workpiece peeled from the adjustment peeling layer as a starting point, and adjusting the output of the laser beam to be irradiated to the ingot; a workpiece obtaining step of irradiating the ingot with the output-adjusted laser beam to form a peeling layer and peeling the workpiece from the ingot from the peeling layer as a starting point, to obtain a workpiece having the first remaining peeling layer on one side; and a grinding step of grinding both sides of the adjustment workpiece from which the first remaining peeling layer has been removed and the workpiece having the first remaining peeling layer to manufacture a wafer of a predetermined thickness. In this manufacturing method, the output adjusting step includes a first thickness measuring step of measuring a first thickness, which is the thickness of the ingot before the adjusting release layer is formed; a first separation layer forming step of forming the adjusting release layer on the ingot; a first separation step of separating an adjusting workpiece from the ingot starting from the adjusting release layer; a first ingot grinding step of grinding and removing a second remaining separation layer, which is the separation layer remaining on the ingot, with a separation layer grinding stone; and a second thickness measuring step of measuring a second thickness, which is the thickness of the ingot after the second remaining separation layer has been ground and removed. The method may include a workpiece grinding step in which the first remaining peeling layer of the adjustment workpiece peeled from the ingot is ground off with the peeling layer grinding stone; a third thickness measuring step in which a third thickness is measured, which is the thickness of the adjustment workpiece from which the first remaining peeling layer has been ground off; an adjustment peeling layer thickness measuring step in which the thickness of the adjustment peeling layer is measured by subtracting the second thickness and the third thickness from the first thickness; and an adjustment step in which the output of the laser beam is adjusted so that the thickness of the adjustment peeling layer measured in the adjustment peeling layer thickness measuring step becomes a predetermined thickness. In this manufacturing method, the workpiece obtaining process may include a second peeling layer forming process in which the output-adjusted laser beam is irradiated onto an ingot to form a peeling layer; a second peeling process in which a workpiece having a first remaining peeling layer peeled starting from the peeling layer is obtained, and an ingot having a second remaining peeling layer remaining after the workpiece is peeled; a second ingot grinding process in which, after the second peeling process, the second remaining peeling layer of the ingot is ground off; and a repeating process in which the second peeling layer forming process, the second peeling process, and the second ingot grinding process are repeated to obtain a workpiece having the first remaining peeling layer. In this manufacturing method, the work acquisition process may include mixing the work having the first remaining peeling layer acquired by the repeating process and the adjustment work from which the first remaining peeling layer has been removed acquired in the output adjustment process in a cassette. In this manufacturing method, the grinding process may include a holding process in which the other surface of a workpiece having the first remaining peeling layer on one surface is held on a holding surface of a chuck table, a peeling layer grinding process in which the first remaining peeling layer of the workpiece held on the holding surface is ground away with a peeling layer grinding stone, and a finish grinding process in which grinding marks formed on both surfaces of the workpiece ground with the peeling layer grinding stone are ground away with a finishing grinding stone. In this manufacturing method, the grinding process may include a peeling layer presence / absence determination process for determining whether or not a first remaining peeling layer is present on one side of the workpiece. When it is determined that the first remaining peeling layer is present, the first remaining peeling layer of the workpiece is ground off with a peeling layer grinding stone, and then both sides of the workpiece are ground with a finishing grinding stone. On the other hand, when it is determined that the first remaining peeling layer is not present, grinding with the peeling layer grinding stone is not performed, and both sides of the workpiece may be ground with a finishing grinding stone. In this manufacturing method, the peeling layer presence / absence determination process may include a fourth thickness measurement process for measuring the thickness of the work held on the holding surface, and a thickness determination process for determining that the work has the first remaining peeling layer when the thickness of the work measured in the fourth thickness measurement process is equal to or greater than a predetermined thickness, and determining that the work does not have the first remaining peeling layer when the thickness of the work is thinner than the predetermined thickness. In this manufacturing method, the peeling layer presence / absence determination process may include an imaging process of imaging one side of the workpiece, and an image determination process of determining that the first remaining peeling layer is present in the workpiece when the brightness difference between adjacent pixels in the image obtained by the imaging is greater than or equal to a predetermined difference, and determining that the first remaining peeling layer is not present in the workpiece when the brightness difference between the pixels is less than the predetermined difference. In this manufacturing method, the grinding process may include a first judgment process for determining that the wafer cannot be manufactured when the thickness of the workpiece measured in the fourth thickness measurement process is smaller than at least the sum of the predetermined grinding amount to be ground by the finishing grindstone and the predetermined thickness of the wafer. In this manufacturing method, the grinding process may include a peeling layer presence / absence determination process for determining whether or not a first remaining peeling layer is present on one side of the workpiece. When it is determined that the first remaining peeling layer is present, the first remaining peeling layer of the workpiece is ground away with a peeling layer grindstone, and then both sides of the workpiece are ground with a finishing grindstone. When it is determined that the first remaining peeling layer is absent, the following may be carried out: an additional thickness measurement process for measuring the thickness of the workpiece; and a thickness adjustment grinding process for grinding the workpiece to the reference thickness using the peeling layer grindstone when the thickness measured in the additional thickness measurement process is greater than a reference value, which is the sum of the amount of grinding performed with the finishing grindstone and a predetermined thickness of the wafer. After the thickness adjustment grinding process, a finish grinding process for grinding both sides of the workpiece with a finishing grindstone may be carried out. The grinding device used in this manufacturing method (this grinding device) includes a cassette stage for placing a cassette containing a workpiece thereon, a chuck table for holding the workpiece by a holding surface, a peeling layer grinding mechanism for grinding the first remaining peeling layer of the workpiece held on the holding surface with a peeling layer grindstone, a finish grinding mechanism for grinding the workpiece held on the holding surface with a finish grindstone, a transport mechanism for transporting the workpiece between the cassette stage and the chuck table, an inversion mechanism for inverting the top and bottom surfaces of the workpiece, and a thickness grinding mechanism for grinding the workpiece held on the holding surface with a finish grindstone. The workpiece is provided with a thickness measuring device that measures the thickness of the workpiece, a peeling layer presence / absence detection unit that detects whether the first remaining peeling layer is present on one side of the workpiece, and a control unit. When the peeling layer presence / absence detection unit determines that the first remaining peeling layer is present, the control unit controls to grind the first remaining peeling layer of the workpiece with a peeling layer grindstone and then grind both sides of the workpiece with a finishing grindstone, but when the peeling layer presence / absence detection unit determines that the first remaining peeling layer is not present, the control unit controls to grind both sides of the workpiece with a finishing grindstone without performing grinding with the peeling layer grindstone. In this grinding device, the peeling layer presence / absence detection unit may be provided with a thickness determination section that measures the thickness of the workpiece held on the holding surface using the thickness measuring device, and determines that the workpiece has the first remaining peeling layer when the thickness of the workpiece is equal to or greater than a predetermined thickness, and determines that the workpiece does not have the first remaining peeling layer when the thickness of the workpiece does not reach the predetermined thickness. In this grinding device, the peeling layer presence / absence detection unit may include a camera that captures an image of one side of the workpiece, and an image judgment unit that determines that the first remaining peeling layer is present on the workpiece when the brightness difference between adjacent pixels in the image captured by the camera is greater than or equal to a predetermined difference, and that the first remaining peeling layer is not present on the workpiece when the brightness difference between the pixels is less than the predetermined difference. [Effects of the Invention]

[0012] In this manufacturing method, both sides of the workpiece are ground to produce wafers of a predetermined thickness, whether the workpiece has a first remaining peeling layer on one side or is an adjustment workpiece that does not have a first remaining peeling layer. In other words, in this manufacturing method, because both sides of the workpiece are ground, similar wafers can be produced from two types of workpieces regardless of whether one side has a first remaining peeling layer. Therefore, even if two types of workpieces are mixed, wafers of a predetermined thickness can be easily produced from these workpieces. Therefore, the overall processing time can be shortened compared to grinding two types of workpieces separately. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a perspective view showing the configuration of the laser processing device. [Figure 2] FIG. 2 is an explanatory diagram showing a grinding unit. [Figure 3] FIG. 2 is a perspective view showing a cassette stage and a cassette. [Figure 4] FIG. 2 is a perspective view showing a first robot. [Figure 5] FIG. 10 is a perspective view showing a first release layer forming step and a second release layer forming step. [Figure 6] FIG. 2 is an explanatory diagram showing a peeling layer formed on an ingot. [Figure 7] FIG. 2 is a perspective view showing a first peeling step and a second peeling step. [Figure 8] FIG. 2 is a perspective view showing a first peeling step and a second peeling step. [Figure 9] FIG. 2 is a perspective view showing a workpiece obtained in the first peeling step and the second peeling step. [Figure 10] FIG. 2 is a perspective view showing an ingot obtained in the first peeling step and the second peeling step. [Figure 11] FIG. 2 is an explanatory diagram showing the configuration of a grinding device. [Figure 12] FIG. 10 is an explanatory diagram showing an example of a captured image of the first remaining peeling layer. [Figure 13] 10 is a flowchart showing an example of a grinding process. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1, and then grinding the plate-like workpiece (described later) obtained by peeling from this peeling layer with a grinding wheel to produce a wafer. To form the peeling layer, a laser beam that is transparent to the ingot 86 is irradiated from the first end face 88 side of the ingot 86, and the focal point focused at a predetermined depth is moved parallel to the first end face 88 to form a planar peeling layer parallel to the first end face 88.

[0015] This manufacturing method includes a power adjustment step, a workpiece obtaining step, and a grinding step. In the power adjustment step, the power of the laser beam irradiated onto the ingot 86 is adjusted. In the workpiece obtaining step, the ingot 86 is irradiated with the power-adjusted laser beam to form a peeling layer, and the workpiece is obtained by peeling it from the ingot 86 starting from this peeling layer. In the grinding step, both sides of the workpiece are ground to produce a wafer of a predetermined thickness.

[0016] 1 is an apparatus for performing the above-described output adjustment process and workpiece acquisition process. The laser processing apparatus 1 includes a holding unit 4 for holding an ingot 86, a laser beam application unit 8 having a condenser 6 and using a laser beam to form a strip-shaped peeling layer on the ingot 86, an X-axis feed unit 10 for relatively feeding the holding unit 4 and the condenser 6 in the X-axis direction, a Y-axis feed unit 12 for relatively indexing and feeding the holding unit 4 and the condenser 6 in the Y-axis direction, and a first control unit 16.

[0017] The laser processing apparatus 1 processes a cylindrical ingot 86 made of, for example, SiC. The ingot 86 has a circular first end face 88, a circular second end face 90 opposite the first end face 88, and an outer peripheral surface 92. In addition, a rectangular first orientation flat 96 and a second orientation flat 98, both of which indicate crystal orientation, are formed on the outer peripheral surface 92 of the ingot 86.

[0018] As shown in FIG. 6, the ingot 86 is aligned along the c-axis 511 ( <0001> The c-axis 511 extends from the first end face 88 to the second end face 90 and is tilted at an off angle α with respect to a normal 513 to the first end face 88. The off angle α can be set freely within a range of, for example, 1° to 6°. The off angle α shown in FIG. 6 is 4°. The first orientation flat 96 is parallel to the direction in which the off angle α is formed. The second orientation flat 98 is perpendicular to the direction in which the off angle α is formed.

[0019] 1 is configured to hold such an ingot 86. Holding unit 4 includes an X-axis movable plate 20 mounted on base 18 so as to be movable in the X-axis direction, guide rails 21 on X-axis movable plate 20, a Y-axis movable plate 22 mounted on X-axis movable plate 20 so as to be movable in the Y-axis direction, a circular holding table 24 rotatably mounted on the upper surface of Y-axis movable plate 22, and a holding table motor (not shown) that rotates holding table 24.

[0020] X-axis feed unit 10 has a ball screw 38 that extends in the X-axis direction along the upper surface of base 18, and a motor 40 that rotates ball screw 38. A nut portion (not shown) of ball screw 38 is connected to X-axis movable plate 20 of holding unit 4. In X-axis feed unit 10, ball screw 38 is rotated by motor 40, whereby X-axis movable plate 20 is moved in the X-axis direction along guide rails 19 on base 18.

[0021] Y-axis feed unit 12 has a ball screw 42 that extends in the Y-axis direction along the upper surface of X-axis movable plate 20, and a motor 44 that rotates ball screw 42. A nut portion (not shown) of ball screw 42 is connected to Y-axis movable plate 22 of holding unit 4. In Y-axis feed unit 12, motor 44 rotates ball screw 42, thereby moving Y-axis movable plate 22 in the Y-axis direction along guide rails 21 on X-axis movable plate 20.

[0022] The laser beam application unit 8 forms a peeling layer by using a laser beam on the ingot 86 held by the holding unit 4. The laser beam application unit 8 includes a housing 26 provided on the base 18 and a condenser 6 provided in the housing 26.

[0023] The housing 26 contains an oscillator that emits a laser beam of a wavelength that is transparent to the ingot 86, an attenuator that adjusts the output of the laser beam, and a mirror that reflects the laser beam and directs it to the collector 6 (all not shown).

[0024] The condenser 6 positions the focal point of the laser beam at a depth in the ingot 86 that corresponds to the thickness of the workpiece to be produced, and irradiates the ingot 86 with the laser beam.

[0025] An imaging unit 34 for capturing an image of the ingot 86 held in the holding unit 4 is attached to the lower surface at the tip of the housing 26. A display device 36 for displaying an image captured by the imaging unit 34 is also disposed on the upper surface of the housing 26.

[0026] Further, in the vicinity of the imaging unit 34 in the housing 26, a thickness measuring device 37 for measuring the thickness of the ingot 86 or workpiece held on the holding table 24 of the holding unit 4 is provided.

[0027] The thickness measuring device 37 is, for example, a laser-type thickness measuring device that measures the thickness of the ingot 86 or workpiece being measured in a non-contact manner. In this case, the thickness measuring device 37 irradiates the object with a laser beam having a wavelength that penetrates the object, receives light reflected from the bottom surface and the top surface of the object, and measures the thickness of the object based on the optical path difference between the reflected light. Alternatively, the thickness measuring device 37 may be a spectroscopic interference wafer thickness measuring device that measures the thickness of the object by analyzing the interference light between the light reflected from the bottom surface and the light reflected from the top surface of the object. Note that the measuring light may be in the visible to infrared wavelength range. The thickness measuring device 37 may also include an SLD (Super Luminescent Diode) as a light source that emits the measuring light. The thickness measuring device 37 may be a non-contact top surface measuring device using a white light confocal method, a non-contact top surface height measuring device using a triangulation method, or a contact top surface height measuring device that reads the height position of a probe that is brought into contact with the top surface of the workpiece, and may measure the thickness of the workpiece by calculating the difference between the holding surface and the top surface height.

[0028] The laser processing apparatus 1 further includes a peeling unit 50 that peels the wafer from the ingot 86 starting from the peeling layer, and a grinding unit 52 that grinds the first end surface 88 of the ingot 86 to form a flat surface.

[0029] The peeling unit 50 includes a casing 54 disposed at the terminal end of the guide rail 19 on the base 18, an arm 56 extending in the X-axis direction from a base end supported on the casing 54 so as to be freely raised and lowered, and an arm lifting unit (not shown) for raising and lowering the arm 56. The arm lifting unit has, for example, a ball screw connected to the arm 56 and extending in the vertical direction, and a motor for rotating the ball screw.

[0030] A motor 58 is attached to the tip of the arm 56, and a suction piece 60 is connected to the underside of the motor 58 so as to be rotatable about an axis extending in the vertical direction. A plurality of suction holes (not shown) are formed in the underside of the suction piece 60, and the suction piece 60 is connected to a suction unit 61 (see FIG. 7). The suction piece 60 also has a built-in ultrasonic vibration imparting unit (not shown) that imparts ultrasonic vibrations to the underside of the suction piece 60.

[0031] The grinding unit 52 includes a column 62, a lifting plate 64 attached to one side of the column 62 so as to be able to move up and down, and a lifting unit 66 that raises and lowers the lifting plate 64. The lifting unit 66 has a ball screw 68 that extends in the vertical direction along one side of the column 62, and a motor 70 that rotates the ball screw 68. A nut portion (not shown) of the ball screw 68 is connected to the lifting plate 64. In the lifting unit 66, the ball screw 68 is rotated by the motor 70, thereby raising and lowering the lifting plate 64 along a guide rail 63 attached to one side of the column 62.

[0032] A support wall 72 protruding in the Y-axis direction is fixed to one surface of the lifting plate 64. A spindle 74 is supported on the support wall 72 so as to be rotatable about an axis extending in the vertical direction. A spindle motor 76 that rotates the spindle 74 is mounted on the upper surface of the support wall 72.

[0033] 1 and 2, a disk-shaped wheel mount 78 is fixed to the lower end of the spindle 74, and an annular grinding wheel 82 is fixed to the underside of the wheel mount 78 by bolts 80. A plurality of exfoliation layer grinding stones 84 are fixed to the outer peripheral edge of the underside of the grinding wheel 82, and are arranged annularly and spaced apart in the circumferential direction. In this embodiment, the exfoliation layer grinding stones 84 are grinding stones that remove the remaining exfoliation layer remaining on the ingot 86 or workpiece.

[0034] On the front side (-Y direction side) of the base 18 of the laser processing device 1, a cassette unit 110 and a first robot 115 are provided.

[0035] 3, the cassette unit 110 includes a cassette stage 111 and a first cassette 112 placed on the cassette stage 111. The first cassette 112 includes multiple shelves therein, and each shelf can accommodate one workpiece.

[0036] An opening (not shown) of the first cassette 112 faces the -X direction. A first robot 115 is disposed on the -X side of this opening. As shown in FIG. 3 , the first robot 115 includes a robot hand 116 having a holding surface 118 that holds a workpiece, and a movement mechanism 117 that moves the robot hand 116. The first robot 115 is configured to store the workpiece obtained by the laser processing apparatus 1 in the first cassette 112 of the cassette unit 110.

[0037] The first control unit 16 includes a CPU that performs calculations according to a control program, a storage medium such as a memory, etc. The first control unit 16 controls the above-mentioned components of the laser processing apparatus 1 to perform processing on the ingot 86.

[0038] Next, the output adjustment step and workpiece acquisition step of this manufacturing method, which are carried out by the laser processing device 1, will be described.

[0039] [1. Output adjustment process] First, the output adjustment process will be described. In the output adjustment step, an adjustment peeling layer is formed on the ingot 86, and a first remaining peeling layer, which is a peeling layer remaining on the adjustment workpiece peeled from this adjustment peeling layer as a starting point, and a second remaining peeling layer, which is a peeling layer remaining on the ingot 86, are removed to adjust the output of the laser beam irradiated onto the ingot 86. The output adjustment step will be specifically described below.

[0040] (1-1. First thickness measurement process) First, an operator uses an appropriate adhesive to fix the ingot 86 to the upper surface of the holding table 24 of the holding unit 4 so that the first end surface 88 faces upward. This causes the ingot 86 to be held on the holding table 24. Note that a plurality of suction holes may be formed in the upper surface of the holding table 24, and the ingot 86 may be held by suction using the upper surface of the holding table 24.

[0041] Next, first control unit 16 uses X-axis feed unit 10 and Y-axis feed unit 12 to position holding table 24, which holds ingot 86, below thickness measuring device 37. Then, first control unit 16 uses thickness measuring device 37 to measure the first thickness, which is the thickness of ingot 86 held on holding table 24. The thickness gauge 37 that measures the thickness of the ingot 86 calculates the difference between the height of the upper surface of the holding table 24 and the height of the upper surface of the ingot 86 held on the holding table 24 as the first thickness.

[0042] In this embodiment, the first end surface 88 is flattened in advance by the peeling layer grindstone 84 of the grinding unit 52. If the first end surface 88 is not flattened, the first control unit 16 flattens the first end surface 88 using the peeling layer grindstone 84 of the grinding unit 52 before measurement by the thickness measuring device 37. This flattening of the first end surface 88 makes it possible to form a first peeling layer in the next step.

[0043] (1-2. First release layer forming step) Next, the first control unit 16 carries out a first separation layer forming step of forming an adjustment separation layer on the ingot 86.

[0044] In the first peeling layer forming step, first, the first control unit 16 uses the X-axis feed unit 10 and the Y-axis feed unit 12 to position the holding table 24 holding the ingot 86 below the imaging unit 34. Then, the first control unit 16 causes the imaging unit 34 to capture an image of the ingot 86 from above the ingot 86.

[0045] Next, based on the image of the ingot 86 captured by the imaging unit 34, the first control unit 16 adjusts the orientation of the ingot 86 to a predetermined orientation and adjusts the positions of the ingot 86 and the collector 6 in the XY plane by moving and rotating the holding table 24 using the X-axis feed unit 10, the Y-axis feed unit 12, and the holding table motor. When adjusting the orientation of the ingot 86 to a predetermined orientation, as shown in FIG. 5, by aligning the second orientation flat 98 with the X-axis direction, the direction perpendicular to the direction 501 in which the off angle α (see FIG. 6) is formed is aligned with the X-axis direction, and the direction 501 in which the off angle α is formed is aligned with the Y-axis direction.

[0046] Next, the first control unit 16 raises and lowers the condenser 6 using the condenser position adjustment unit, thereby positioning the condenser 602 (see FIG. 6 ) of the laser beam 601 at a depth (first depth) from the first end face 88 of the ingot 86 that corresponds to the thickness of the workpiece to be produced. The depth (first depth) from the first end face 88 at which the condenser 602 is positioned can be found using the value of the height of the upper surface of the ingot 86 measured by the thickness measuring device 37. Next, the first control unit 16 irradiates the ingot 86 with the laser beam 601, which has a wavelength that is transparent to the ingot 86, from the condenser 6 while feeding the holding table 24 in the X-axis direction at a predetermined processing feed rate.

[0047] 5 and 6, modified portion 515 is formed in a portion of ingot 86 from first end face 88 to a first depth. Modified portion 515 is formed when SiC in ingot 86 is separated into Si (silicon) and C (carbon) by irradiation with laser beam 601, and the next laser beam 601 is absorbed by the previously formed C, resulting in a chain reaction of separation of SiC into Si and C.

[0048] In this way, modified regions 515 are continuously formed in the X-axis direction, which is perpendicular to the direction 501 in which the off angle α is formed. Furthermore, cracks 516 are generated that extend isotropically along the c-plane from modified regions 515. As a result, peeling layer 517, which includes modified regions 515 and cracks 516, is continuously formed along the X-axis direction.

[0049] Following this peeling layer formation process, the first control unit 16 uses the Y-axis feed unit 12 to relatively index and feed the ingot 86 and the focal point 602 in the Y-axis direction by a predetermined indexing feed amount 620 within a range that does not exceed the width of the crack 516.

[0050] The first control unit 16 then alternately repeats the peeling layer forming process and the indexing feed, thereby forming a plurality of peeling layers 517 that extend continuously in the X-axis direction at intervals of a predetermined indexing feed amount 620 in the Y-axis direction.

[0051] In this way, a plurality of peeling layers 517 can be sequentially formed along the X-axis direction in the portion from the first end surface 88 of the ingot 86 to the first depth. The peeling layers 517 are portions whose strength has been reduced due to the modified portions 515 and the cracks 516, and serve as interfaces for peeling the workpiece from the ingot 86. In this embodiment, the release layer 517 formed in the first release layer forming step is used as an adjustment release layer.

[0052] (1-3. First peeling process) Next, the first control unit 16 carries out a first peeling step of peeling the workpiece for adjustment from the ingot 86 starting from the peeling layer for adjustment.

[0053] In the first peeling process, the first control unit 16 first uses the X-axis feed unit 10 and the Y-axis feed unit 12 to position the holding table 24 holding the ingot 86 below the suction piece 60 of the peeling unit 50, as shown in Figure 7.

[0054] Next, the first control unit 16 lowers the arm 56 using the arm lifting unit, and as shown in FIG. 8, the lower surface of the chucking piece 60 is brought into close contact with the first end surface 88 of the ingot 86. Next, the first control unit 16 activates the suction unit 61, and causes the lower surface of the chucking piece 60 to be chucking-contacted with the first end surface 88 of the ingot 86. Next, the first control unit 16 activates the ultrasonic vibration imparting unit to impart ultrasonic vibration to the lower surface of the chucking piece 60, and also rotates the chucking piece 60 using the motor 58. This allows the adjustment workpiece 700 to be peeled off from the ingot 86 starting from the adjustment peeling layer, as shown in FIG.

[0055] 9, a first remaining peeling layer 900, which is a part of the adjustment peeling layer, remains on a peeling surface 701, which is one surface of the adjustment workpiece 700. Furthermore, as shown in FIG. 10, a second remaining peeling layer 89, which is a part of the adjustment peeling layer, also remains on a first end surface 88 of the ingot 86 after the adjustment workpiece 700 has been peeled off. The other surface of the adjustment workpiece 700 corresponds to the first end surface 88 of the ingot 86 before the first separation step, and is flattened.

[0056] (1-4. First ingot grinding process) Next, the first control unit 16 carries out a first ingot grinding step in which a second remaining peeled layer 89, which is a remaining peeled layer of the ingot 86, is ground and removed by the peeled layer grindstone .

[0057] In the first ingot grinding step, first, first, the first control unit 16 positions the holding table 24 below the grinding wheel 82 of the grinding unit 52, as shown in FIG. 2, using the X-axis feed unit 10 and the Y-axis feed unit 12 (see FIG. 1). Next, the first control unit 16 rotates the holding table 24 counterclockwise as viewed from above using the holding table motor of the holding unit 4. The first control unit 16 also rotates the spindle 74 counterclockwise as viewed from above using the spindle motor 76 of the grinding unit 52 (see FIG. 1).

[0058] Next, the first control unit 16 uses the lifting unit 66 of the grinding unit 52 to lower the spindle 74, bringing the exfoliation layer grinding wheel 84 into contact with the first end surface 88 of the ingot 86. Thereafter, the first control unit 16 lowers the spindle 74 at a predetermined grinding feed rate, thereby grinding the first end surface 88 of the ingot 86 with the exfoliation layer grinding wheel 84. This allows the second remaining exfoliation layer 89 formed on the first end surface 88 of the ingot 86 to be ground and removed. Note that, by this grinding, the second remaining exfoliation layer 89 is removed and the first end surface 88 is flattened, leaving grinding marks 87 made by the exfoliation layer grinding wheel 84.

[0059] (1-5. Second thickness measurement process) Next, the first control unit 16 measures the second thickness, which is the thickness of the ingot 86 from which the second remaining peeling layer 89 has been ground away, using the thickness gauge 37 in the same manner as in the first thickness measurement step.

[0060] (1-6. Workpiece grinding process) Next, the first control unit 16 carries out a workpiece grinding step in which a first remaining peeled layer 900, which is a remaining peeled layer of the adjustment workpiece 700 peeled from the ingot 86, is ground and removed by the peeled layer grindstone .

[0061] That is, first, the worker removes the ingot 86 from the holding table 24 of the holding unit 4, and holds the adjustment workpiece 700 on the holding table 24 so that the peeled surface 701 on which the first remaining peeled layer 900 is formed faces upward. A transport mechanism for transporting the adjustment workpiece 700 separated from the ingot 86 to the holding table 24 may be provided.

[0062] Thereafter, the first control unit 16 uses the peeling layer grinding stone 84 to grind the first remaining peeling layer 900 of the workpiece for adjustment 700 held on the holding table 24 of the holding unit 4 from the peeled surface 701, in the same manner as in the first ingot grinding process described above. This makes it possible to grind and remove the first remaining peeling layer 900 formed on the workpiece for adjustment 700. Note that this grinding turns the workpiece for adjustment 700 into a workpiece with both surfaces flattened. Also, grinding marks (not shown) caused by the peeling layer grinding stone 84 are formed on both surfaces of the workpiece for adjustment 700.

[0063] (1-7. Third thickness measurement process) Next, the first control unit 16 measures the third thickness, which is the thickness of the work for adjustment 700 from which the first remaining peeling layer 900 has been ground away, using the thickness gauge 37, as in the first thickness measurement step. After this third thickness measurement step, the work for adjustment 700 is stored in the first cassette 112 of the cassette unit 110 shown in Fig. 3 by the first robot 115 shown in Fig. 4.

[0064] (1-8. Adjustment release layer thickness measurement process) Next, the first control unit 16 measures the thickness of the adjustment peeling layer formed on the ingot 86 in the first peeling layer formation process by subtracting the second thickness, which is the thickness of the ingot 86 after the adjustment work 700 is peeled and the second remaining peeling layer 89 is removed, and the third thickness, which is the thickness of the adjustment work 700 after the first remaining peeling layer 900 is removed, from the first thickness, which is the thickness of the ingot 86 before the adjustment work 700 is peeled.

[0065] (1-9. Output adjustment process) Next, the first control unit 16 adjusts the output of the laser beam irradiated from the condenser 6 by controlling the attenuator of the laser beam irradiation unit 8, etc., so that the thickness of the adjustment release layer measured in the adjustment release layer thickness measurement process becomes the predetermined thickness.

[0066] [2. Workpiece acquisition process] Next, the workpiece acquisition process will be described. In the workpiece obtaining process, the laser beam whose output has been adjusted in the output adjustment process is irradiated onto the ingot 86 to form a peeling layer, and the workpiece is peeled from the ingot starting from this peeling layer, thereby obtaining a workpiece having a first remaining peeling layer 900.

[0067] (2-1. Second release layer forming step) In the second peeling layer forming process, an operator holds the ingot 86 on the holding table 24 of the holding unit 4 with the first end face 88 facing upward (see FIG. 5). Then, the first control unit 16 irradiates the ingot 86 from the first end face 88 side with a laser beam whose output has been adjusted to form a peeling layer 517. That is, similar to the first peeling layer forming process described above, the first control unit 16 positions the focal point 602 (see FIG. 6) of the laser beam 601 whose output has been adjusted at a depth (first depth) from the first end face 88 of the ingot 86 that corresponds to the thickness of the workpiece to be produced, and forms the peeling layer 517 at this position.

[0068] (2-2. Second peeling process) Next, the first control unit 16 performs a second peeling process to obtain a workpiece having a first remaining peeling layer 900 peeled starting from the peeling layer 517, and an ingot 86 having a second remaining peeling layer 89 remaining after the workpiece is peeled.

[0069] In the second peeling step, the first control unit 16 uses the peeling unit 50 to peel the workpiece from the ingot 86 held on the holding table 24, in the same manner as in the first peeling step described above. Hereinafter, the workpiece obtained in the second peeling step will be referred to as a normal workpiece 800 (see FIG. 9).

[0070] 9, a first remaining peeled layer 900, which is a part of the peeled layer, remains on a peeled surface 801, which is one surface of the normal workpiece 800. The other surface of the normal workpiece 800 has been flattened by a second ingot grinding process, which will be described later.

[0071] 10, a second remaining peeling layer 89, which is part of the peeling layer, also remains on the first end surface 88 of the ingot 86 after the workpiece 800 has been peeled off. In this way, the first control unit 16 obtains the workpiece having the first remaining peeling layer 900 on one surface and the ingot 86 having the second remaining peeling layer 89 on the first end surface 88.

[0072] (2-2. Second ingot grinding process) After the second peeling step, the first control unit 16 grinds and removes the second remaining peeling layer 89 of the ingot 86. That is, similar to the first ingot grinding step described above, the first control unit 16 grinds the first end surface 88 of the ingot 86 held on the holding table 24 of the holding unit 4 using the peeling layer grindstone 84 (see FIG. 2). This grinds and removes the second remaining peeling layer 89 formed on the first end surface 88 of the ingot 86, thereby flattening the first end surface 88. Note that this grinding leaves grinding marks 87 on the first end surface 88 of the ingot 86.

[0073] (2-3. Repeat process) Then, the first control unit 16 repeats the above-mentioned second peeling layer forming process, second peeling process, and second ingot grinding process to obtain multiple normal workpieces 800 having a first remaining peeling layer 900 on one side.

[0074] The normal workpiece 800 is stored in the first cassette 112 of the cassette unit 110 shown in Fig. 3 by the first robot 115 shown in Fig. 4. That is, the workpiece obtaining step includes mixing, in the first cassette 112, the normal workpiece 800 having the first remaining peeling layer 900 obtained by the repeating step and the adjustment workpiece 700 from which the first remaining peeling layer 900 has been removed, obtained in the output adjustment step.

[0075] In this way, the first cassette 112 can accommodate the normal workpiece 800, which has the first remaining release layer 900 on one side and the other side that is flattened, and the adjustment workpiece 700, which has both one side and the other side that is flattened and does not have the first remaining release layer 900. The first robot 115 accommodates the adjustment workpiece 700 and the normal workpiece 800 in the first cassette 112 so that one side of each of them faces upward. Therefore, the normal workpiece 800 is accommodated in the first cassette 112 so that the side on which the first remaining release layer 900 is formed faces upward.

[0076] In this embodiment, the normal workpiece 800 and the adjustment workpiece 700 are ground into wafers of a predetermined thickness in the grinding step of this manufacturing method. The grinding step is performed by a grinding device 120 shown in FIG.

[0077] First, the configuration of the grinding device 120 will be described. The grinding device 120 includes a peeling layer grinding mechanism 132 and a finish grinding mechanism 133, and grinds the workpiece held on the chuck table 140 using the peeling layer grinding mechanism 132 and the finish grinding mechanism 133. The expression "workpiece to be processed" refers to the workpiece to be ground by the grinding device 120, that is, either the adjustment workpiece 700 or the normal workpiece 800.

[0078] The grinding device 120 has a first device base 122 and a second device base 123 disposed behind the first device base 122 (on the +Y direction side).

[0079] On the front side (-Y direction side) of the first device base 122, a first cassette stage 160 and a second cassette stage 162 are provided for placing cassettes containing workpieces to be machined.

[0080] The first cassette 112 described above, which contains workpieces to be machined before machining, is placed on the first cassette stage 160. The second cassette stage 162 is placed on the second cassette 163, which contains workpieces to be machined after machining.

[0081] The openings (not shown) of the first cassette 112 and the second cassette 163 face the +Y direction side. The second robot 155 is disposed on the +Y direction side of these openings. The second robot 155 and a carry-in mechanism 170 and a carry-out mechanism 172 (described later) function as a transfer mechanism that transfers the workpiece or wafer between the cassette stages 160 and 162 and the chuck table 140 .

[0082] The second robot 155 has the same configuration as the first robot 115. That is, as shown in Fig. 3, the second robot 155 includes a robot hand 116 having a holding surface 118 that holds a workpiece, and a movement mechanism 117 that moves the robot hand 116.

[0083] The second robot 155 carries in (stores) the processed workpiece into the second cassette 163. The second robot 155 also takes out the unprocessed workpiece from the first cassette 112 and places it on the temporary placement table 154 with one surface facing upward. As described above, one surface of the adjustment workpiece 700 is flat, and one surface of the normal workpiece 800 has the first remaining peeling layer 900 formed thereon.

[0084] The second robot 155 is also capable of inverting the workpiece it holds. That is, the second robot 155 also functions as an inversion mechanism that inverts the top and bottom surfaces of the workpiece.

[0085] A camera 152 is provided near the temporary placement table 154. The camera 152 captures an image of one surface of the workpiece placed on the temporary placement table 154. The camera 152 is connected to an image determination unit 153, which will be described later.

[0086] Furthermore, a carry-in mechanism 170 is provided at a position adjacent to the temporary placement table 154. The carry-in mechanism 170 suction-holds the workpiece temporarily placed on the temporary placement table 154 with a suction pad 171, and places the workpiece on the holding surface 142 of the chuck table 140 with one surface facing upward.

[0087] The holding surface 142 of the chuck table 140 is connected to a suction source (not shown) and is capable of suction-holding the workpiece. With the holding surface 142 holding the workpiece by suction, the chuck table 140 is rotatable about a central axis that passes through the center of the holding surface 142 and extends in the Z-axis direction.

[0088] In this embodiment, three chuck tables 140 are disposed at equal intervals on the upper surface of a turntable 145 disposed on the second apparatus base 123 on a circle centered at the center of the turntable 145. A rotation shaft (not shown) for rotating the turntable 145 is disposed at the center of the turntable 145. This rotation shaft allows the turntable 145 to rotate about an axis extending in the Z-axis direction. The rotation of the turntable 145 causes the three chuck tables 140 to revolve. This allows the chuck tables 140 to be positioned sequentially near the temporary placement table 154, below the peeling layer grinding mechanism 132, and below the finish grinding mechanism 133.

[0089] A first column 124 is erected at the rear (+Y direction side) of the second device base 123. A peeling layer grinding mechanism 132 and a peeling layer grinding feed mechanism 130 that feeds the peeling layer grinding mechanism 132 for grinding are disposed in front of the first column 124.

[0090] The peeling layer grinding feed mechanism 130 includes a pair of guide rails 201 parallel to the Z-axis direction, a lifting table 203 that slides on the guide rails 201, a ball screw 200 parallel to the guide rails 201, a motor 202 that rotates and drives the ball screw 200, and a holder 204 attached to the lifting table 203. The holder 204 holds the peeling layer grinding mechanism 132.

[0091] The lift table 203 is slidably installed on the guide rail 201. A nut portion (not shown) is fixed to the lift table 203. A ball screw 200 is threadedly engaged with this nut portion. The motor 202 is connected to one end of the ball screw 200.

[0092] In the peeling layer grinding feed mechanism 130, the motor 202 rotates the ball screw 200, causing the lifting table 203 to move in the Z-axis direction along the guide rail 201. As a result, the holder 204 attached to the lifting table 203 and the peeling layer grinding mechanism 132 held by the holder 204 also move in the Z-axis direction together with the lifting table 203. In this way, the peeling layer grinding feed mechanism 130 grinds and feeds the peeling layer grinding mechanism 132 along the Z-axis direction.

[0093] The peeling layer grinding mechanism 132 grinds the first remaining peeling layer 900 of the normal workpiece 800 held on the holding surface 142 of the chuck table 140 using a peeling layer grindstone 306. The peeling layer grinding mechanism 132 includes a spindle housing 301 fixed to the holder 204, a spindle 300 rotatably held by the spindle housing 301, a motor 302 that rotates and drives the spindle 300, a wheel mount 303 attached to the lower end of the spindle 300, and a grinding wheel 304 detachably connected to the lower surface of the wheel mount 303.

[0094] The spindle housing 301 is held by the holder 204 so as to extend in the Z-axis direction. The spindle 300 extends in the Z-axis direction so as to be perpendicular to the holding surface 142 of the chuck table 140, and is rotatably supported by the spindle housing 301.

[0095] The motor 302 is connected to the upper end side of the spindle 300. The motor 302 causes the spindle 300 to rotate about a rotation axis extending in the Z-axis direction.

[0096] The wheel mount 303 is formed in a disk shape, is fixed to the lower end (tip) of the spindle 300, and rotates in accordance with the rotation of the spindle 300. The wheel mount 303 supports the grinding wheel 304.

[0097] The grinding wheel 304 is formed so that its outer diameter is approximately the same as the outer diameter of the wheel mount 303. The grinding wheel 304 includes an annular wheel base 305 made of, for example, a metal material. A plurality of approximately rectangular parallelepiped exfoliation grinding stones 306 are fixed to the underside of the wheel base 305 in an annular arrangement around the entire circumference. The exfoliation grinding stones 306 are rotated by the rotation of the spindle 300 and grind the workpiece held on the chuck table 140. The exfoliation grinding stones 306 are, for example, grinding stones containing relatively large abrasive grains.

[0098] A first height gauge 143 is disposed adjacent to the chuck table 140, which is disposed below the peeling layer grinding mechanism 132. The first height gauge 143 and a second height gauge 144, which will be described later, are thickness measuring devices that measure the thickness of the workpiece held on the holding surface 142. The first height gauge 143 measures the thickness of the workpiece by contact or non-contact. A thickness determination unit 141, which will be described later, is connected to the first height gauge 143.

[0099] Furthermore, a second column 125 is erected at the rear of the second device base 123 so as to be adjacent to the first column 124 along the X-axis direction. A finish grinding mechanism 133 that finish-grinds the workpiece to be processed, and a finish grinding feed mechanism 131 that feeds the finish grinding mechanism 133 for grinding are disposed in front of the second column 125. The finish grinding mechanism 133 is an example of a processing mechanism that processes the workpiece held by suction on the holding surface 142.

[0100] The finish grinding feed mechanism 131 has a configuration similar to that of the exfoliation layer grinding feed mechanism 130, and can feed the finish grinding mechanism 133 along the Z-axis direction for grinding. The finish grinding mechanism 133 grinds the workpiece held on the holding surface 142 of the chuck table 140 with a finishing grindstone 307. The finish grinding mechanism 133 has a configuration similar to that of the exfoliation layer grinding mechanism 132, except that it is equipped with a finishing grindstone 307 instead of the exfoliation layer grindstone 306. The finishing grindstone 307 is, for example, a grindstone containing relatively small abrasive grains.

[0101] A second height gauge 144 is disposed adjacent to the chuck table 140 disposed below the finish grinding mechanism 133. The second height gauge 144 measures the thickness of the workpiece by contact or non-contact.

[0102] After finish grinding, the workpiece becomes a wafer of a predetermined thickness and is carried out by the carry-out mechanism 172. The carry-out mechanism 172 suction-holds the wafer held on the chuck table 140 with a suction pad 173 and transports it to the spinner cleaning mechanism 156.

[0103] The spinner cleaning mechanism 156 is a spinner cleaning unit that cleans the wafer. The spinner cleaning mechanism 156 includes a spinner table 157 that holds the wafer, and a nozzle 158 that sprays cleaning water and dry air toward the spinner table 157.

[0104] The wafer cleaned by the spinner cleaning mechanism 156 is carried into a second cassette 163 on a second cassette stage 162 by a second robot 155 .

[0105] The grinding device 120 also includes a housing 135 that covers the first device base 122 and the second device base 123. A touch panel 136 is provided on the side of the housing 135.

[0106] The touch panel 136 displays various types of information related to grinding by the grinding device 120. The touch panel 136 is also used to input various types of information such as device data. In this way, the touch panel 136 functions as a display member for displaying information and also as an input member for inputting information.

[0107] The grinding device 120 also includes a second control unit 180 for controlling the grinding device 120. The second control unit 180 includes a CPU that performs calculations according to a control program, a storage medium such as a memory, etc. The second control unit 180 controls the above-mentioned components of the grinding device 120 to perform the grinding process on the workpiece.

[0108] The grinding step of this manufacturing method, which is carried out by the grinding device 120 having the above-described configuration, will be described below.

[0109] [3. Grinding process] In the grinding step, both surfaces of the adjustment workpiece 700 from which the first remaining peeling layer 900 has been removed and the normal workpiece 800 having the first remaining peeling layer 900 are ground to produce wafers of a predetermined thickness.

[0110] (3-1. Holding process) First, the second control unit 180 causes the second robot 155 to take out the workpiece from the first cassette 112 and place it on the temporary placement table 154 with one surface facing upward. Furthermore, the second control unit 180 causes the carry-in mechanism 170 to place the workpiece temporarily placed on the temporary placement table 154 on the holding surface 142 of the chuck table 140 with one surface facing upward, and causes the other surface of the workpiece to be held on the holding surface 142 (holding step).

[0111] Then, the second control unit 180 rotates the turntable 145 on its axis, thereby positioning the chuck table 140 holding the workpiece below the peeling layer grinding mechanism 132 .

[0112] (3-2. Peel layer presence determination process) In this step, the thickness determination unit 141 determines whether or not the first remaining peeled layer 900 is present on one surface of the workpiece.

[0113] Specifically, the thickness determination unit 141 uses the first height gauge 143 to measure the thickness of the workpiece held on the holding surface 142 of the chuck table 140 (fourth thickness measurement step).

[0114] The thickness determination unit 141 determines that the workpiece has a first remaining peeling layer 900 when the thickness of the workpiece is equal to or greater than a predetermined thickness, and determines that the workpiece does not have a first remaining peeling layer 900 when the thickness of the workpiece does not reach the predetermined thickness (when the thickness is thinner than the predetermined thickness) (thickness determination process).

[0115] In this way, in this peeling layer presence / absence determination process, the first height gauge 143 and thickness determination unit 141 function as a peeling layer presence / absence detection unit that detects whether or not the first remaining peeling layer 900 is present on one side of the workpiece to be processed.

[0116] When the thickness determination unit 141 determines that there is a first remaining peeling layer 900, the second control unit 180 determines that the workpiece to be processed is a normal workpiece 800, and performs the peeling layer grinding process and finish grinding process described below.

[0117] (3-3. Peeling layer grinding process) In the peeling layer grinding step, the second control unit 180 grinds and removes the first remaining peeling layer 900 of the normal workpiece 800 with the peeling layer grindstone 306 .

[0118] Specifically, the second control unit 180 rotates the chuck table 140 holding the normal workpiece 800, and while rotating the peeling layer grinding wheel 306 of the peeling layer grinding mechanism 132, causes the peeling layer grinding feed mechanism 130 to lower the peeling layer grinding mechanism 132 along the Z-axis direction. This causes the peeling layer grinding wheel 306 to come into contact with one side of the normal workpiece 800, and the first remaining peeling layer 900 formed on this side is removed by the peeling layer grinding wheel 306. After this peeling layer grinding process, a finish grinding process is carried out.

[0119] In this peeling layer grinding step, the workpiece 800 is usually ground to a thickness that allows the amount of grinding by the finishing grindstone 307 to remain, that is, to a thickness that allows the portion ground by the finishing grindstone 307 to remain.

[0120] (3-4. Finish grinding process) In the finish grinding step, the second control unit 180 grinds both surfaces of the normal workpiece 800 with the finish grindstone 307 so that the normal workpiece 800 has a predetermined thickness.

[0121] Specifically, the second control unit 180 rotates the turntable 145, thereby positioning the chuck table 140 holding the normal workpiece 800 after the peeling layer grinding process below the finish grinding mechanism 133. Then, the second control unit 180 rotates the chuck table 140 and, while rotating the finishing grindstone 307 of the finish grinding mechanism 133, lowers the finish grinding mechanism 133 along the Z-axis direction using the finish grinding feed mechanism 131. As a result, the finishing grindstone 307 comes into contact with one side of the normal workpiece 800, and finish-grinds this side by a predetermined grinding amount.

[0122] Next, the second control unit 180 inverts the normal workpiece 800 on the chuck table 140 (inverting step). That is, the second control unit 180 rotates the turntable 145, thereby positioning the chuck table 140, which holds the normal workpiece 800 whose one surface has been finish-ground, near the temporary placement table 154. Then, the second control unit 180 transfers the normal workpiece 800 held on the chuck table 140 to the second robot 155 using the carry-out mechanism 172. Then, the second control unit 180 controls the second robot 155 to invert the normal workpiece 800 and place it on the temporary placement table 154 so that the other surface faces upward. Furthermore, the second control unit 180 places the normal workpiece 800 temporarily placed on the temporary placement table 154 on the holding surface 142 of the chuck table 140 using the carry-in mechanism 170 so that the other surface faces upward, and holds the normal workpiece 800 on the holding surface 142.

[0123] Thereafter, the second control unit 180 rotates the turntable 145, and positions the chuck table 140 holding the normal workpiece 800 below the finish grinding mechanism 133. The finish grinding mechanism 133 finish-grinds the other surface of the normal workpiece 800 by a predetermined grinding amount so that the normal workpiece 800 has a predetermined thickness. In this way, a wafer having a predetermined thickness is manufactured from the normal workpiece 800.

[0124] In this finish grinding step, grinding marks formed on one side of the normal workpiece 800 by the peeling layer grindstone 306 and grinding marks formed on the other side of the normal workpiece 800 by the peeling layer grindstone 84 (see FIG. 2) of the laser processing device 1 are ground away by the finishing grindstone 307. In the finish grinding step, for example, both sides of the normal workpiece 800 are ground away by the same amount (for example, 5 μm or 10 μm).

[0125] On the other hand, when the thickness determination unit 141 determines that the workpiece to be processed does not have the first remaining peeling layer 900, the second control unit 180 determines that the workpiece to be processed is the adjustment workpiece 700, and grinds both sides of the adjustment workpiece 700 with the finishing grinding wheel 307 so that the adjustment workpiece 700 has a predetermined thickness without performing grinding with the peeling layer grinding wheel 306.

[0126] That is, the second control unit 180 performs only the above-mentioned finish grinding step without performing the above-mentioned peeling layer grinding step, thereby grinding both surfaces of the workpiece for adjustment 700 with the finishing grindstone 307 so that the workpiece for adjustment 700 has a predetermined thickness. In this finish grinding step, grinding marks formed on the workpiece for adjustment 700 by the peeling layer grindstone 84 (see FIG. 2) of the laser processing device 1 are ground away by the finishing grindstone 307. In this way, a wafer having a predetermined thickness is manufactured from the workpiece for adjustment 700.

[0127] Wafers of a predetermined thickness manufactured from the adjustment workpiece 700 and the normal workpiece 800 are transported by the unloading mechanism 172 to the spinner cleaning mechanism 156 for cleaning, and then transported by the second robot 155 into the second cassette 163 on the second cassette stage 162.

[0128] As described above, in this embodiment, both sides of the workpiece are ground to produce wafers of a predetermined thickness, whether the workpiece is a normal workpiece 800 having the first remaining peeling layer 900 on one side or an adjustment workpiece 700 not having the first remaining peeling layer 900. That is, in this embodiment, because both sides of the workpiece are ground, wafers can be produced from two types of workpieces, regardless of whether one side has the first remaining peeling layer 900. Therefore, even if two types of workpieces are mixed in the first cassette 112, wafers of a predetermined thickness can be easily produced from these workpieces. Therefore, the overall processing time can be shortened compared to grinding the adjustment workpiece 700 and the normal workpiece 800 separately.

[0129] In this embodiment, the thickness determination unit 141 detects whether or not the first remaining peeling layer 900 is present, and based on the detection result, it is determined whether or not to perform the peeling layer grinding process. Therefore, it is possible to perform appropriate grinding processing on the adjustment workpiece 700 and the normal workpiece 800 depending on whether or not the first remaining peeling layer 900 is present.

[0130] The grinding step may include the following first determination step. In this first determination step, the second control unit 180 determines that wafers cannot be manufactured when the thickness of the workpiece measured in the fourth thickness measurement step in the peeling layer presence / absence determination step is smaller than at least the sum of the preset grinding amount to be ground by the finishing grindstone 307 and the preset predetermined thickness of the wafer. Then, the second control unit 180 stops the grinding step without performing the above-mentioned peeling layer grinding step and finish grinding step, and notifies the operator via the touch panel 136 that wafers cannot be manufactured.

[0131] In this embodiment, the peeling layer presence / absence determining step may be performed using the camera 152 and the image determining unit 153. In this case, the peeling layer presence / absence determining step includes the following imaging step and image determining step.

[0132] In the imaging process, the second control unit 180 uses the camera 152 to capture an image of one side of the workpiece placed on the temporary placement table 154 with one side facing upward, thereby obtaining an image (imaging process).

[0133] When the first remaining peeling layer 900 is present on one side of the workpiece, an image of the first remaining peeling layer 900 is obtained as an image of that side. As shown in Fig. 12, in the image of the first remaining peeling layer 900, gray and black areas are arranged adjacent to each other in a mixed manner. On the other hand, when the first remaining peeling layer 900 is not present on one side of the workpiece, an image (not shown) of a flat ground surface ground by the peeling layer grinding wheel 84 (see Fig. 2) of the laser processing apparatus 1 is obtained as an image of that side. In the image of the ground surface, only a substantially uniform gray area is displayed.

[0134] Next, the image determination unit 153 determines whether the difference in brightness between adjacent pixels in the image captured by the camera 152 is equal to or greater than a preset difference.

[0135] As described above, in the captured image of the first remaining peeling layer 900, gray and black portions are arranged adjacent to each other, so the brightness difference between adjacent pixels in the captured image is relatively large. Therefore, the image determination unit 153 determines that the first remaining peeling layer 900 is present in the workpiece when the brightness difference between the pixels is equal to or greater than a preset difference.

[0136] On the other hand, in an image of the grinding surface acquired when there is no first remaining peeling layer 900, only a substantially uniform gray portion is displayed, and therefore the brightness difference between adjacent pixels in the image is relatively small. Therefore, when the brightness difference between pixels is smaller than a preset difference, the image determination unit 153 determines that there is no first remaining peeling layer 900 in the workpiece (image determination step).

[0137] When the image judgment unit 153 determines that the workpiece has a first remaining peeling layer 900, the second control unit 180 determines that the workpiece is a normal workpiece 800 and carries out the above-mentioned peeling layer grinding process and finish grinding process.

[0138] On the other hand, when the image judgment unit 153 determines that the workpiece to be processed does not have the first remaining peeling layer 900, the second control unit 180 determines that the workpiece to be processed is an adjustment workpiece 700, and performs only the finish grinding process without performing the above-mentioned peeling layer grinding process.

[0139] In this way, in this peeling layer presence / absence determination process, the camera 152 and the image determination unit 153 function as a peeling layer presence / absence detection unit that detects whether or not the first remaining peeling layer 900 is present on one side of the workpiece to be processed.

[0140] The second control unit 180 may also carry out the grinding process according to the flowchart shown in FIG. First, the second control unit 180 performs the holding step described above to position the chuck table 140 holding the workpiece below the peeling layer grinding mechanism 132 (S1).

[0141] Next, the second control unit 180 performs a step of determining the presence or absence of a peeled layer based on the thickness of the workpiece using the first height gauge 143 and the thickness determination unit 141 (S2). The second control unit 180 may perform the peeling layer presence / absence determination step based on a captured image of the workpiece using the camera 152 and the image determination unit 153.

[0142] Then, when the second control unit 180 determines in the peeling layer presence / absence determining step that the first remaining peeling layer 900 is present in the workpiece to be machined (S3; YES), it determines that the workpiece to be machined is the normal workpiece 800. Then, the second control unit 180 performs the above-mentioned peeling layer grinding step (S4) to grind and remove the first remaining peeling layer 900 from the normal workpiece 800 by the peeling layer grindstone 306. Furthermore, the second control unit 180 carries out the above-mentioned finish grinding process (S5) to grind both sides of the normal workpiece 800 with the finishing grindstone 307 so that the normal workpiece 800 has a predetermined thickness, thereby producing a wafer of a predetermined thickness and completing the grinding process.

[0143] On the other hand, when the second control unit 180 determines in the peeling layer presence / absence determination step that the workpiece to be processed does not have the first remaining peeling layer 900 (S3; NO), it determines that the workpiece to be processed is the adjustment workpiece 700. Then, the second control unit 180 performs an additional thickness measurement step (S6) in which the first height gauge 143 (see FIG. 11) is used to measure the thickness of the adjustment workpiece 700 held on the holding surface 142 of the chuck table 140.

[0144] Then, the second control unit 180 determines whether the thickness of the adjustment workpiece 700 measured in the additional thickness measurement step is thicker than a reference value (S7). This reference value is the sum of a preset grinding amount to be ground by the finishing grindstone 307 and a preset predetermined thickness of the wafer (thickness of the wafer obtained by the finish grinding step).

[0145] If the thickness of the adjustment workpiece 700 measured in the additional thickness measurement step is greater than the reference value (S7; YES), the second control unit 180 carries out a thickness adjustment grinding step (S8).

[0146] As described above, grinding marks made by the peeling layer grindstone 84 (see FIG. 2) of the laser processing apparatus 1 are formed on the workpiece for adjustment 700. Then, in this thickness adjustment grinding step, the second control unit 180 causes the peeling layer grindstone 306 of the grinding apparatus 120 to form grinding marks that intersect with the grinding marks made by the peeling layer grindstone 84 made on the workpiece for adjustment 700, while grinding the workpiece for adjustment 700 to a thickness (i.e., a reference value) obtained by adding the grinding amount made by the finishing grindstone 307 and a predetermined thickness of the wafer that has been set in advance.

[0147] Specifically, when one surface of the workpiece for adjustment 700 held on the rotating chuck table 140 is ground by the rotating exfoliation layer grindstone 306, the second control unit 180 appropriately adjusts at least one of the tilt of the chuck table 140, the rotation direction of the chuck table 140, and the rotation direction of the exfoliation layer grindstone 306. In this way, the second control unit 180 can grind one surface of the workpiece for adjustment 700 by the exfoliation layer grindstone 306 so as to form grinding marks that intersect with the grinding marks formed by the exfoliation layer grindstone 84 on one surface of the workpiece for adjustment 700.

[0148] The second control unit 180 performs such grinding using the peeling layer grindstone 306 until the thickness of the adjustment workpiece 700 reaches the reference value.

[0149] The second control unit 180 may grind one surface of the workpiece for adjustment 700 by a predetermined amount with the peeling layer grindstone 306, and then perform the above-described inversion step to hold the workpiece for adjustment 700 on the chuck table 140 so that the other surface faces upward. Then, the second control unit 180 may grind the other surface of the workpiece for adjustment 700 with the peeling layer grindstone 306 so as to form grinding marks that intersect with the grinding marks formed on this surface by the peeling layer grindstone 84, and set the thickness of the workpiece for adjustment 700 to the reference thickness.

[0150] Thereafter, the second control unit 180 carries out the above-mentioned finish grinding process (S5) to grind both sides of the adjustment workpiece 700 with the finishing grindstone 307 so that the adjustment workpiece 700 has a predetermined thickness, thereby producing a wafer of a predetermined thickness and completing the grinding process.

[0151] On the other hand, if the thickness of the adjustment work 700 measured in the additional thickness measurement step is equal to or less than the reference value (S7; NO), the second control unit 180 performs the first judgment step described above and determines that wafers cannot be manufactured. Then, the second control unit 180 stops the grinding step without performing the peeling layer grinding step and the finish grinding step described above, and notifies the operator, using the touch panel 136, that wafers cannot be manufactured.

[0152] In this grinding process, the workpiece for adjustment 700 is ground by the peeling layer grindstone 306, and then ground by the finishing grindstone 307. Therefore, wear on the finishing grindstone 307 can be suppressed compared to a configuration in which the workpiece for adjustment 700 is ground only by the finishing grindstone 307. [Explanation of symbols]

[0153] 1: laser processing device, 4: holding unit, 6: condenser, 8: Laser beam irradiation unit, 10: X-axis feed unit, 12: Y-axis feed unit, 16: first control unit, 18: base, 19: guide rail, 20: X-axis movable plate, 21: guide rail, 22: Y-axis movable plate, 24: holding table, 26: Housing, 34: Imaging unit, 36: Display device, 37: Thickness measuring device, 38: Ball screw, 40: Motor, 42: Ball screw, 44: Motor, 50: peeling unit, 52: grinding unit, 54: casing, 56: arm, 58: motor, 60: suction piece, 61: suction unit, 62: column, 63: Guide rail, 64: Lifting plate, 66: Lifting unit, 68: Ball screw, 70: motor, 72: support wall, 74: spindle, 76: spindle motor, 78: Wheel mount, 80: Bolt, 82: Grinding wheel, 84: Peeling layer grinding stone, 86: ingot, 87: grinding marks, 88: first end face, 89: second remaining peeled layer, 90: second end surface, 92: outer peripheral surface, 96: first orientation flat, 98: Second orientation flat, 110: Cassette unit, 111: cassette stage, 112: first cassette, 115: first robot, 116: Robot hand, 117: Moving mechanism, 120: Grinding device, 122: first device base, 123: second device base, 124: first column, 125: second column, 130: peeling layer grinding feed mechanism, 131: finish grinding feed mechanism, 132: peeling layer grinding mechanism, 133: finish grinding mechanism, 135: Housing, 136: Touch panel, 140: Chuck table, 141: thickness determination unit, 142: holding surface, 143: first height gauge, 144: Second height gauge, 145: Turntable, 152: Camera, 153: Image judgment unit, 154: Temporary placement table, 155: Second robot, 156: Spinner cleaning mechanism, 157: Spinner table, 158: Nozzle, 160: first cassette stage, 162: second cassette stage, 163: Second cassette, 170: Loading mechanism, 171: Suction pad, 172: Loading mechanism, 173: suction pad, 180: second control unit, 200: ball screw, 201: guide rail, 202: motor, 203: lift table, 204: holder, 300: spindle, 301: spindle housing, 302: motor, 303: wheel mount, 304: grinding wheel, 305: Wheel base, 306: Peeling layer grinding stone, 307: Finishing grinding stone, 501: direction, 511: c-axis, 512: c-plane, 513: perpendicular line, 515: modified portion, 516: crack, 517: peeling layer, 601: laser beam, 602: focusing point, 620: Indexing feed amount, 700: Adjustment workpiece, 701: Peeling surface, 800: Normal workpiece, 801: Peeling surface, 900: First remaining peeling layer

Claims

1. A method for manufacturing a wafer, comprising: irradiating one surface of an ingot with a laser beam that is transparent to the ingot; moving a focal point of the laser beam focused at a predetermined depth parallel to the one surface to form a peeling layer; peeling the workpiece from the peeling layer as a starting point to obtain a plate-like workpiece; and grinding the workpiece with a grinding wheel to manufacture a wafer; an output adjustment step of forming an adjustment release layer on the ingot, removing a first remaining release layer, which is a release layer remaining on the adjustment workpiece peeled from the adjustment release layer as a starting point, and adjusting the output of the laser beam irradiated onto the ingot; a workpiece obtaining step of irradiating the ingot with the output-adjusted laser beam to form a peeling layer, and peeling the workpiece from the ingot starting from the peeling layer to obtain a workpiece having a first remaining peeling layer on one surface; a grinding step of grinding both surfaces of the adjustment work from which the first remaining peeling layer has been removed and the work having the first remaining peeling layer to produce a wafer of a predetermined thickness.

2. The output adjustment step includes: a first thickness measurement step of measuring a first thickness, which is the thickness of the ingot before forming the adjusting separation layer; a first separation layer forming step of forming the adjustment separation layer on the ingot; a first peeling step of peeling the workpiece for adjustment from the ingot starting from the peeling layer for adjustment; a first ingot grinding step of grinding and removing a second remaining peeling layer, which is a peeling layer remaining on the ingot, with a peeling layer grindstone; a second thickness measuring step of measuring a second thickness, which is the thickness of the ingot after the second remaining peeling layer has been ground away; a workpiece grinding step of grinding and removing the first remaining peeled layer of the adjustment workpiece peeled from the ingot with the peeled layer grindstone; a third thickness measuring step of measuring a third thickness, which is the thickness of the adjustment workpiece from which the first remaining peeling layer has been ground and removed; a thickness measurement step of measuring the thickness of the adjusting release layer by subtracting the second thickness and the third thickness from the first thickness; and an adjusting step of adjusting the output of the laser beam so that the thickness of the adjustment release layer measured in the adjusting release layer thickness measuring step becomes a preset thickness.

2. A method for manufacturing a wafer according to claim 1.

3. The workpiece acquisition step includes: a second separation layer forming step of irradiating the ingot with the output-adjusted laser beam to form a separation layer; a second peeling step of obtaining a workpiece having a first remaining peeled layer peeled from the peeled layer as a starting point, and an ingot having a second remaining peeled layer remaining after the workpiece is peeled; a second ingot grinding step of grinding and removing the second remaining peeled layer of the ingot after the second peeling step; a repeating step of repeating the second peeling layer forming step, the second peeling step, and the second ingot grinding step to obtain a workpiece having the first remaining peeling layer, 2. A method for manufacturing a wafer according to claim 1.

4. The workpiece acquisition step includes: The method includes mixing the workpiece having the first remaining peeling layer obtained by the repeating step and the workpiece for adjustment from which the first remaining peeling layer has been removed obtained in the output adjusting step in a cassette. The method for manufacturing a wafer according to claim 3.

5. The grinding step includes: a holding step of holding the other surface of the workpiece having the first remaining peeling layer on one surface by a holding surface of a chuck table; a peeling layer grinding step of grinding and removing the first remaining peeling layer of the workpiece held on the holding surface with a peeling layer grindstone; and a finish grinding process in which grinding marks formed on both surfaces of the workpiece ground with the peeling layer grindstone are ground off with a finishing grindstone.

2. A method for manufacturing a wafer according to claim 1.

6. The grinding step includes: a peeling layer presence / absence determination step for determining whether or not a first remaining peeling layer is present on one surface of the workpiece; When it is determined that the first remaining peeling layer is present, the first remaining peeling layer of the workpiece is ground and removed with a peeling layer grindstone, and then both surfaces of the workpiece are ground with a finishing grindstone. When it is determined that the first remaining peeled layer does not exist, grinding of the peeled layer with the grindstone is not performed, and both surfaces of the workpiece are ground with the finishing grindstone.

2. A method for manufacturing a wafer according to claim 1.

7. The step of determining whether or not a peeling layer is present includes: a fourth thickness measurement step of measuring the thickness of the workpiece held on the holding surface; and a thickness determination step of determining that the first remaining peeling layer is present in the workpiece when the thickness of the workpiece measured in the fourth thickness measurement step is equal to or greater than a predetermined thickness, and determining that the first remaining peeling layer is not present in the workpiece when the thickness of the workpiece is thinner than the predetermined thickness. The method for manufacturing a wafer according to claim 6.

8. The step of determining whether or not a peeling layer is present includes: an imaging step of imaging one surface of the workpiece; and an image determination step of determining that the first remaining peeling layer is present in the workpiece when the brightness difference between adjacent pixels in the captured image obtained by the imaging is equal to or greater than a preset difference, and determining that the first remaining peeling layer is not present in the workpiece when the brightness difference between the pixels is smaller than the preset difference. The method for manufacturing a wafer according to claim 6.

9. The grinding step includes: a first determination step of determining that wafers cannot be manufactured when the thickness of the workpiece measured in the fourth thickness measurement step is smaller than at least a value obtained by adding a preset grinding amount to be ground by the finishing grindstone and a preset predetermined thickness of the wafer; The method for manufacturing a wafer according to claim 7.

10. The grinding step includes: a peeling layer presence / absence determination step for determining whether or not a first remaining peeling layer is present on one surface of the workpiece; When it is determined that the first remaining peeling layer is present, the first remaining peeling layer of the workpiece is ground and removed with a peeling layer grindstone, and then both surfaces of the workpiece are ground with a finishing grindstone. When it is determined that the first remaining release layer does not exist, an additional thickness measurement step of measuring the thickness of the workpiece; a thickness adjustment grinding step in which, when the thickness measured in the additional thickness measurement step is greater than a reference value which is the sum of the amount of grinding by the finishing grindstone and a predetermined thickness of the wafer that has been set in advance, the workpiece is ground to the thickness of the reference value while forming grinding marks by the peeling layer grindstone that intersect with the grinding marks formed on the workpiece; After the thickness adjustment grinding step, a finish grinding step is carried out in which both surfaces of the workpiece are ground with a finishing grindstone.

2. A method for manufacturing a wafer according to claim 1.

11. 2. A grinding apparatus used in the wafer manufacturing method according to claim 1, a cassette stage for placing a cassette containing the workpiece; a chuck table that holds the workpiece by a holding surface; a peeling layer grinding mechanism that grinds the first remaining peeling layer of the workpiece held on the holding surface with a peeling layer grindstone; a finish grinding mechanism that grinds the workpiece held on the holding surface with a finish grindstone; a transport mechanism that transports a workpiece between the cassette stage and the chuck table; An inversion mechanism that inverts the top and bottom surfaces of the workpiece; a thickness measuring device for measuring the thickness of the workpiece held on the holding surface; a peeled layer presence / absence detection unit that detects whether or not the first remaining peeled layer is present on one surface of the workpiece; a control unit, The control unit When the peeling layer presence / absence detection unit determines that the first remaining peeling layer is present, the first remaining peeling layer of the workpiece is ground and removed with a peeling layer grindstone, and then both surfaces of the workpiece are ground with a finishing grindstone; When the peeling layer presence / absence detection unit determines that the first remaining peeling layer does not exist, control is performed to not perform grinding with the peeling layer grindstone, but to grind both surfaces of the workpiece with finishing grindstones. Grinding equipment.

12. The peeling layer presence detection unit comprises: a thickness determination unit that measures the thickness of the workpiece held on the holding surface by the thickness measuring device, and determines that the first remaining peeling layer is present on the workpiece when the thickness of the workpiece is equal to or greater than a predetermined thickness, and determines that the first remaining peeling layer is not present on the workpiece when the thickness of the workpiece does not reach the predetermined thickness; The grinding device according to claim 11.

13. The peeling layer presence detection unit comprises: a camera that captures an image of one surface of the workpiece; and an image determination unit that determines that the first remaining peeling layer is present on the workpiece when the brightness difference between adjacent pixels in the image captured by the camera is equal to or greater than a preset difference, and that the first remaining peeling layer is not present on the workpiece when the brightness difference between the pixels is smaller than the preset difference. The grinding device according to claim 11.

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