Grinding apparatus and plate-shaped object manufacturing method

Abstract

To provide a grinding device capable of efficiently and accurately grinding even in a small amount of grinding, and a plate-like object manufacturing method.SOLUTION: The first thickness measurement unit (70) measures the thickness of the workpiece (90) held on the holding surface (321) of the chuck table (31) positioned at the first processing position. The second thickness measurement unit (71) measures the thickness of the workpiece (90) held on the holding surface (321) of the chuck table (31) positioned at the second processing position. The thickness measurement position of the workpiece (90) is different between the first thickness measurement portion (70) and the second thickness measurement portion (71).SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a grinding device for grinding a plate-shaped workpiece and a method for manufacturing a plate-shaped workpiece. For example, the present invention relates to a small-volume grinding technique of Z1 (rough grinding) / Z2 (finish grinding) using a thickness measuring device (thickness measuring gauge). [Background technology]

[0002] When manufacturing silicon carbide (SiC) or silicon plate-shaped products, wafers (as-sliced ​​wafers) are cut from an ingot using a wire saw or other tool, and then ground (rough grinding and finish grinding) to remove any waviness or irregularities on the surface. The less grinding is done, the more wafers (number of wafers) can be removed from the ingot, so a small amount of grinding is required.

[0003] Furthermore, the grinding apparatus may measure the wafer thickness during grinding to obtain a predetermined grinding amount (removal thickness). For example, Patent Document 1 describes a grinding apparatus having a thickness measurement unit that measures the thickness of a workpiece held on the holding surface of a chuck table. The grinding method using the grinding apparatus includes a grinding amount command step, in which a target thickness of the workpiece, previously registered in a control unit, is subtracted from the thickness of the workpiece to calculate a planned grinding amount, and the control unit commands the calculated planned grinding amount to a servo driver of a grinding feed unit. Furthermore, in the grinding amount command step, the thickness measurement unit repeatedly measures the thickness of the workpiece until it reaches the target thickness, updates the planned grinding amount by the value obtained by subtracting the target thickness from the measured thickness of the workpiece, and repeatedly commands the servo driver of the grinding feed unit to update the planned grinding amount. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-000711 Summary of the Invention [Problem to be solved by the invention]

[0005] However, according to the inventor's extensive research, depending on the accuracy of the thickness measuring device (thickness measuring unit), a certain amount of grinding is required to ensure stable measurement accuracy, making small-scale grinding impossible. When grinding is performed in two stages, rough grinding, which has high processing efficiency, and subsequent finish grinding, to efficiently achieve high finish accuracy, a certain amount of grinding must be performed on each axis to stabilize measurement accuracy in each grinding process, making small-scale grinding more difficult. Thus, prior art, including Patent Document 1, prioritizes the measurement accuracy of the thickness measuring device (thickness measuring unit), and therefore unintentionally or unwillingly requires a larger amount of grinding. Therefore, there is room for improvement, for example, in terms of increasing the yield (number) of plate-shaped objects from an ingot.

[0006] An object of the present invention is to provide a grinding device and a method for manufacturing a plate-shaped object that are capable of grinding even a small amount of material efficiently and accurately. [Means for solving the problem]

[0007] A grinding device according to one aspect of the present invention includes a chuck table having a holding surface for holding a plate-shaped workpiece and rotating about an axis intersecting the holding surface as a rotation axis; a first spindle having a first grinding wheel of a disk shape with a grinding stone attached thereto and rotating the first grinding wheel in a circumferential direction; a second spindle having a second grinding wheel of a disk shape with a grinding stone attached thereto and rotating the second grinding wheel in a circumferential direction; and a grinding device for positioning the chuck table at a first processing position where the first grinding wheel attached to the first spindle can grind the workpiece held on the holding surface, and a second processing position where the second grinding wheel attached to the second spindle can grind the workpiece held on the holding surface. a first grinding feed unit having a first motor for relatively moving the chuck table and the first spindle in directions toward or away from each other; a second grinding feed unit having a second motor for relatively moving the chuck table and the second spindle in directions toward or away from each other; a first thickness measuring unit for measuring the thickness of the workpiece held on the holding surface of the chuck table positioned at the first processing position; and a second thickness measuring unit for measuring the thickness of the workpiece held on the holding surface of the chuck table positioned at the second processing position, wherein the thickness measuring position of the workpiece differs between the first thickness measuring unit and the second thickness measuring unit.

[0008] The angle formed between the rotation axis of the first spindle and the holding surface of the chuck table may be different from the angle formed between the rotation axis of the second spindle and the holding surface of the chuck table.

[0009] The distance between the thickness measurement position of the first thickness measurement unit and the rotation axis of the chuck table positioned at the first processing position may be smaller than the distance between the thickness measurement position of the second thickness measurement unit and the rotation axis of the chuck table positioned at the second processing position.

[0010] The workpiece is formed in an approximately circular plate shape when viewed in a plane, and is ground with different grinding amounts in the radial direction in a rough grinding process as a first process, and is ground with different grinding amounts in the radial direction in a finish grinding process as a second process, the first thickness measuring unit measures the grinding amount both before and after the rough grinding process as the first process at a first radial position of the approximately circular plate-shaped workpiece, and the second thickness measuring unit measures the grinding amount both before and after the finish grinding process as the second process at a second radial position of the approximately circular plate-shaped workpiece, and the first radial position and the second radial position may be different from each other.

[0011] A grinding device according to one embodiment of the present invention comprises a chuck table having a holding surface for holding a plate-shaped workpiece and rotating about an axis intersecting the holding surface as its rotation axis; a spindle having a disk-shaped grinding wheel with a grinding stone attached thereto and rotating the grinding wheel in a circumferential direction; a grinding feed unit that moves the chuck table and the spindle relatively toward or away from each other; a thickness measuring unit that measures the thickness of the workpiece held on the holding surface of the chuck table; and an angle changing unit that changes the relative angle between the holding surface of the chuck table and the grinding wheel attached to the spindle, wherein the thickness measuring unit measures the thickness of the workpiece held on the holding surface of the chuck table at a first measurement position and a second measurement position different from the first measurement position.

[0012] A method for manufacturing a plate-shaped workpiece according to one aspect of the present invention includes a first processing step in which a first grinding feed unit moves a disk-shaped first grinding wheel having a grinding stone toward a plate-shaped workpiece held on a holding surface of a chuck table positioned at a first processing position by a chuck table moving unit while rotating the first grinding wheel in a circumferential direction by a first spindle, and moves the disk-shaped first grinding wheel toward the plate-shaped workpiece held on the holding surface of the chuck table positioned at a second processing position by the chuck table moving unit, and moves the disk-shaped second grinding wheel toward the plate-shaped workpiece held on the holding surface of the chuck table positioned at a second processing position by rotating the second spindle. and a second machining step of bringing the workpiece into contact with the workpiece and machining the workpiece, the first machining step comprising a first grinding step of grinding the workpiece, and a first thickness measuring step of detecting a state of the first grinding step based on a first measurement value obtained by measuring the thickness of the workpiece at a first thickness measurement position with a first thickness measuring unit and a first set value that has been set in advance, and the second machining step comprising a second grinding step of grinding the workpiece, and a second thickness measuring step of detecting a state of the second grinding step based on a second measurement value obtained by measuring the thickness of the workpiece at a second thickness measurement position with a second thickness measuring unit and a second set value that has been set in advance, the first thickness measurement position and the second thickness measurement position being different.

[0013] A method for manufacturing a plate-shaped workpiece according to one aspect of the present invention includes a first processing step of rotating a first grinding wheel having a grinding stone in a circumferential direction by a spindle while bringing the first grinding wheel, which is a disk-shaped grinding wheel, close to the plate-shaped workpiece held on a holding surface of a chuck table by a grinding feed unit, and processing the workpiece; a wheel changing step of replacing the first grinding wheel attached to the spindle with a second grinding wheel having a grinding stone; an angle changing step of changing the relative angle between the holding surface of the chuck table and the rotation axis of the spindle by an angle changing unit; and a second grinding wheel moving the second grinding wheel by the spindle toward the workpiece ground in the first processing step and held on the holding surface of the chuck table. and a second machining step in which the workpiece is machined by rotating it in a circumferential direction and bringing it closer together by the grinding feed unit, wherein the first machining step includes a first grinding step in which the workpiece is grinded, and a first thickness measurement step in which the condition of the workpiece is detected based on a first measurement value obtained by measuring the thickness of the workpiece at a first thickness measurement position by the thickness measurement unit and a first preset value, and the second machining step includes a second grinding step in which the workpiece is grinded, and a second thickness measurement step in which the condition of the workpiece is detected based on a second measurement value obtained by measuring the thickness of the workpiece at a second thickness measurement position by the thickness measurement unit and a second preset value, wherein the first thickness measurement position and the second thickness measurement position are different.

[0014] The thickness change at the first thickness measurement position in the first grinding process may be greater than the measurement accuracy of the thickness measurement unit or the first thickness measurement unit at the first thickness measurement position, and the thickness change at the second thickness measurement position in the second grinding process may be greater than the measurement accuracy of the thickness measurement unit or the second thickness measurement unit at the second thickness measurement position.

[0015] The abrasive grains contained in the grinding stones of the first grinding wheel and the second grinding wheel may have an average grain size of 4.0 μm or less. [Effects of the Invention]

[0016] According to the above aspects, it is possible to provide a grinding device and a method for manufacturing a plate-shaped object that are capable of grinding even a small amount efficiently and accurately. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a perspective view of a grinding device according to an embodiment of the present invention. [Figure 2] FIG. 4 is a cross-sectional view showing the chuck table and the second grinding mechanism. [Figure 3] FIG. 2 is a side view showing the chuck table and the tilt adjustment mechanism. [Figure 4] FIG. 4 is a cross-sectional view showing a part of the chuck table and the tilt adjustment mechanism. [Figure 5] FIG. 10 is a plan view showing an example of the arrangement of the tilt adjustment mechanism. [Figure 6] FIG. 2 is a perspective view showing a chuck table, a tilt adjustment mechanism, and a chuck rotation unit. [Figure 7] FIG. 2 is a block diagram showing a control system of the grinding apparatus. [Figure 8] 1 is a first diagram showing the relationship between the change in shape of the wafer due to the first and second grinding steps and the thickness measurement positions by the first and second thickness measurement units. FIG. [Figure 9] FIG. 2 is a second diagram showing the relationship between the change in shape of the wafer due to the first and second grinding steps and the thickness measurement positions by the first and second thickness measurement units. [Figure 10] FIG. 3 is a third diagram showing the relationship between the change in shape of the wafer due to the first and second grinding steps and the thickness measurement positions by the first and second thickness measurement units. DETAILED DESCRIPTION OF THE INVENTION

[0018] The grinding device and the method for manufacturing a plate-shaped object according to this embodiment will be described below with reference to the accompanying drawings. Fig. 1 is a perspective view of the grinding device according to this embodiment. Note that the grinding device to which the present invention is applied is not limited to the configuration shown in Fig. 1 as long as it performs grinding of a wafer with a first grinding wheel (first grinding wheel) and a second grinding wheel (second grinding wheel).

[0019] The grinding machine to which the present invention is applied can be applied to both a single-spindle machine having one spindle on which a disc-shaped grinding wheel having a grinding wheel (grinding wheel) is attached and which rotates the grinding wheel in the circumferential direction, and a twin-spindle machine having two such spindles. When the grinding machine is a single-spindle machine, a grinding wheel having a grinding wheel for rough grinding is attached to the spindle to perform a rough grinding process (first grinding process), and then a grinding wheel having a grinding wheel for finish grinding is attached to the spindle (wheel exchange) to perform a finish grinding process (second grinding process). When the grinding machine is a twin-spindle machine, a grinding wheel having a grinding wheel for rough grinding is attached to the rough grinding spindle, and a grinding wheel having a grinding wheel for finish grinding is attached to the finish grinding spindle, and the rough grinding process (first grinding process) and the finish grinding process (second grinding process) are performed in order without wheel exchange.

[0020] The grinding device 1 shown in FIG. 1 is a fully automatic type processing device, and is configured to automatically perform a series of operations for a wafer 90, which is a workpiece (plate-like object), including a loading process, a rough grinding process (first grinding process, first processing process), a finish grinding process (second grinding process, second processing process), a cleaning process, and a loading process.

[0021] The wafer 90 is formed in a substantially circular disk shape when viewed from above, and is carried into the grinding apparatus 1 with a protective tape (not shown) attached to its underside. The wafer 90 may be a semiconductor substrate made of silicon carbide (SiC), silicon, gallium arsenide, or the like, or may be an inorganic material substrate made of ceramic, glass, sapphire, or the like, or may even be a package substrate for a semiconductor product. The wafer 90 may also be carried into the grinding apparatus 1 without a protective tape attached to its underside.

[0022] The X-axis, Y-axis, and Z-axis directions of the grinding apparatus 1 are perpendicular to one another. The X-axis and Y-axis directions are approximately horizontal, and the Z-axis direction is an up-down direction (vertical direction). Of the two arrows indicating the X-axis direction, the side marked with the letter X is the front, and the side without the letter X is the rear. Of the two arrows indicating the Y-axis direction, the side marked with the letter Y is the left, and the side without the letter Y is the right. Of the two arrows indicating the Z-axis direction, the side marked with the letter Z is the up, and the side without the letter Z is the down.

[0023] A pair of cassettes 11 containing a plurality of wafers 90 are placed on the front side of a base 10 of the grinding apparatus 1. A robot hand 12 is provided behind the pair of cassettes 11 to put the wafers 90 into and take them out of the cassettes 11. The robot hand 12 is configured by providing a hand unit 14 at the tip of a robot arm 13 made up of a multi-joint link.

[0024] A positioning mechanism 15 for positioning the wafer 90 before grinding is provided diagonally to the rear right of the robot hand 12. The positioning mechanism 15 is configured by arranging a plurality of positioning pins 17 around a temporary placement table 16, the positioning pins 17 being movable forward and backward in the radial direction of the temporary placement table 16. In the positioning mechanism 15, the plurality of positioning pins 17 abut against the outer periphery of the wafer 90 placed on the temporary placement table 16, thereby positioning the wafer 90 so that its center coincides with the center of the temporary placement table 16.

[0025] A cleaning mechanism 18 for cleaning the ground wafer 90 is provided diagonally to the rear left of the robot hand 12. The cleaning mechanism 18 is configured with various nozzles (not shown) that spray cleaning water and dry air toward a spinner table (not shown). In the cleaning mechanism 18, the spinner table holding the wafer 90 is lowered into the base 10, cleaning water is sprayed onto the wafer 90 within the base 10 to spin-clean it, and then dry air is blown onto the wafer 90 to dry it.

[0026] The robot hand 12 transports the wafer 90 before grinding from the cassette 11 to the positioning mechanism 15, and transports the wafer 90 after grinding from the cleaning mechanism 18 to the cassette 11.

[0027] Between the positioning mechanism 15 and the cleaning mechanism 18, there are provided a loading mechanism 20 for loading the wafer 90 before grinding onto the chuck table 31, and an unloading mechanism 23 for unloading the wafer 90 after grinding from the chuck table 31.

[0028] The loading mechanism 20 is configured by providing a holding pad 22 at the tip of a support arm 21 that is rotatable about an axis in the Z-axis direction on the base 10. In the loading mechanism 20, the wafer 90 is suction-held by the holding pad 22, and the wafer 90 is lifted from the temporary placement table 16. The holding pad 22 is then rotated by the support arm 21, whereby the wafer 90 is loaded onto the chuck table 31.

[0029] The unloading mechanism 23 is configured by providing a holding pad 25 at the tip of a support arm 24 that is rotatable about an axis in the Z-axis direction on the base 10. In the unloading mechanism 23, the holding pad 25 suction-holds the wafer 90 and lifts the wafer 90 from the chuck table 31. The holding pad 25 is then rotated by the support arm 24, whereby the wafer 90 is unloaded from the chuck table 31 to the cleaning mechanism 18.

[0030] A turntable 30 having three chuck tables 31 arranged at equal intervals in the circumferential direction is provided behind the carry-in mechanism 20 and the carry-out mechanism 23. The turntable 30 is rotatable about a rotation axis in the Z-axis direction, and is rotationally driven by a table drive mechanism (not shown).

[0031] 2, each chuck table 31 has a porous member 32 on its top, and the porous member 32 is connected to a suction source (not shown). The upper surface of the porous member 32 forms a holding surface 321 that holds the wafer 90 by suction. Each chuck table 31 is supported rotatably about a central axis 311 that passes through the center of the holding surface 321. The structure that supports the chuck table 31 will be described later.

[0032] 2, the holding surface 321 of each chuck table 31 is formed as a conical surface whose apex is located on the central axis 311 and which gradually becomes lower toward the outer periphery of the chuck table 31. The wafer 90 placed on the chuck table 31 is held in a state conforming to the conical shape of the holding surface 321. When a protective tape is attached to the wafer 90 to be suction-held, the holding surface 321 suction-holds the protective tape and suction-holds the wafer 90 via the protective tape. Note that in FIG. 2, the inclination of the holding surface 321 relative to the horizontal direction and the inclination of the central axis 311 relative to the vertical direction are exaggerated, and in reality, the inclination is so slight that it is not discernible with the naked eye.

[0033] 8 to 10, the wafer 90 of this embodiment has a characteristic shape (particularly a shape in a roughly ground state) for efficiently and accurately grinding even a small amount of grinding in cooperation with a thickness measurement gauge (first thickness measurement unit) 70 and a thickness measurement gauge (second thickness measurement unit) 71, which will be described later. In this sense, the shape of the holding surface 321 of the chuck table 31 illustrated in Fig. 2 and the shape of the wafer 90 held by the holding surface are conceptual, and the shape of the wafer 90, which will be described later with reference to Figs. 8 to 10, will be referred to preferentially.

[0034] In this way, each chuck table 31 has a holding surface 321 that holds a wafer (plate-shaped workpiece) 90, and is configured to be able to rotate around a central axis 311 that intersects with the holding surface 321 as the rotation axis.

[0035] The three chuck tables 31 are positioned, in this order, as the turntable 30 rotates intermittently at 120-degree intervals: a load / unload position where the wafer 90 is loaded and unloaded by the load mechanism 20 and the unload mechanism 23; a first grinding position (first processing position) where the first grinding wheel (grinding wheel) 51 of the first grinding mechanism 50 grinds the wafer 90; and a second grinding position (second processing position) where the second grinding wheel (grinding wheel) 61 of the second grinding mechanism 60 grinds the wafer 90. At the first grinding position, the first grinding wheel 51 roughly grinds the wafer 90 on the chuck table 31 to a predetermined thickness and shape. At the second grinding position, the second grinding wheel 61 finish-grinds the wafer 90 on the chuck table 31 to a desired thickness and shape.

[0036] The turntable 30 functions as a "chuck table moving unit" that positions the chuck table 31 at a "first processing position (first grinding position)" where the wafer (plate-shaped workpiece) 90 held on the holding surface 321 of the chuck table 31 can be ground by the first grinding mechanism 50 (where the first grinding wheel 54 attached to the first spindle 52 described later can grind), and at a "second processing position (second grinding position)" where the wafer (plate-shaped workpiece) 90 held on the holding surface 321 of the chuck table 31 can be ground by the second grinding mechanism 60 (where the second grinding wheel 64 attached to the second spindle 62 described later can grind).

[0037] The first grinding mechanism 50 has a disk-shaped mount 53 at the lower end of a first spindle 52 extending in the Z-axis direction, and a grinding wheel (first grinding wheel) 54 is attached to the lower part of the mount 53. A first grinding stone 51 is arranged in an annular shape on the underside of the grinding wheel 54.

[0038] In the first grinding mechanism 50, a disk-shaped grinding wheel (first grinding wheel) 54 having a first grindstone (grinding stone) 51 is attached to a first spindle 52, and the first spindle 52 rotates the grinding wheel (first grinding wheel) 54 in the circumferential direction. This causes the first grinding mechanism 50 to perform a grinding process (processing process) of the wafer 90, i.e., a rough grinding process.

[0039] The second grinding mechanism 60 has a disk-shaped mount 63 at the lower end of a second spindle 62 extending in the Z-axis direction, and a grinding wheel (second grinding wheel) 64 is attached to the lower part of the mount 63. A second grinding stone 61 is arranged in an annular shape on the underside of the grinding wheel 64.

[0040] In the second grinding mechanism 60, a disk-shaped grinding wheel (second grinding wheel) 64 having a second grindstone (grinding stone) 61 is attached to the second spindle 62, and the second spindle 62 rotates the grinding wheel (second grinding wheel) 64 in the circumferential direction. This causes the second grinding mechanism 60 to perform a grinding process (processing process) of the wafer 90, i.e., a finish grinding process.

[0041] The first spindle 52 and the second spindle 62 are, for example, air spindles, and are supported rotatably about an axis in the Z-axis direction via high-pressure air.

[0042] The first grinding wheel 51 and the second grinding wheel 61 are, for example, diamond grinding wheels formed by bonding diamond abrasive grains with a binder such as a metal bond or a resin bond. The second grinding wheel 61 may be formed of abrasive grains having a finer particle size than the first grinding wheel 51. In other words, the particle size or average particle size of the abrasive grains contained in the second grinding wheel (grinding wheel) 61 of the grinding wheel (second grinding wheel) 64 may be set smaller than the particle size or average particle size of the abrasive grains contained in the first grinding wheel (grinding wheel) 51 of the grinding wheel (first grinding wheel) 54.

[0043] Alternatively, the particle size or average particle size of the abrasive grains contained in the first grinding stone (grinding stone) 51 of the grinding wheel (first grinding wheel) 54 and the particle size or average particle size of the abrasive grains contained in the second grinding stone (grinding stone) 61 of the grinding wheel (second grinding wheel) 64 may be the same (approximately the same). In other words, the first and second grinding wheels (first and second grinding stones) may use grinding wheels (grinding stones) of different particle sizes (different grits), or may use grinding wheels (grinding stones) of the same particle size (same grit). As will be described in more detail later, particularly for the small-amount grinding targeted in this embodiment, it is preferable to use finishing stones (grinding stones with relatively small grain sizes) on both shafts of the first and second grinding wheels (first and second grinding stones), and it is preferable to set the grain sizes or average grain sizes of the abrasive grains contained in the first and second grinding wheels (first and second grinding stones) to be the same or different within such a small grain size range.

[0044] Behind the first grinding position and the second grinding position on the turntable 30, a column 101 on which the first grinding mechanism 50 is supported and a column 102 on which the second grinding mechanism 60 is supported are provided in an upright position.

[0045] A first lifting mechanism for moving the first grinding mechanism 50 up and down is provided on the front surface of the column 101. The first lifting mechanism includes a pair of parallel guide rails 55 (only one is shown) extending in the Z-axis direction on the front surface of the column 101, and a ball screw 56 extending in the Z-axis direction between the pair of guide rails 55. A lifting table 57 is supported on the pair of guide rails 55 so as to be slidable in the Z-axis direction. The first grinding mechanism 50 is supported on the front surface of the lifting table 57 via a housing 58. A ball screw 56 is threadedly engaged with the rear surface of the lifting table 57, and one end of the ball screw 56 is connected to a motor (first motor) 59. The ball screw 56 is rotated by the motor 59, thereby moving the first grinding mechanism 50 along the guide rails 55 in the Z-axis direction.

[0046] The first lifting mechanism functions as a "first grinding feed section" (or may be interpreted as such) having a motor (first motor) 59 that moves the chuck table 31 and the first spindle 52 relatively in directions toward or away from each other.

[0047] A second lifting mechanism for moving the second grinding mechanism 60 up and down is provided on the front surface of the column 102. The second lifting mechanism includes a pair of parallel guide rails 65 (only one is shown) extending in the Z-axis direction on the front surface of the column 102, and a ball screw 66 extending in the Z-axis direction between the pair of guide rails 65. A lifting table 67 is supported on the pair of guide rails 65 so as to be slidable in the Z-axis direction. The second grinding mechanism 60 is supported on the front surface of the lifting table 67 via a housing 68. A ball screw 66 is threadedly engaged with the rear surface of the lifting table 67, and one end of the ball screw 66 is connected to a motor (second motor) 69. The ball screw 66 is rotated by the motor 69, thereby moving the second grinding mechanism 60 along the guide rails 65 in the Z-axis direction.

[0048] The second lifting mechanism functions as a "second grinding feed section" (or may be interpreted as such) having a motor (second motor) 69 that moves the chuck table 31 and the second spindle 62 relatively in directions toward or away from each other.

[0049] A thickness measurement gauge (first thickness measurement unit) 70 and a thickness measurement gauge (second thickness measurement unit) 71 are provided near the turntable 30. The thickness measurement gauge (first thickness measurement unit) 70 measures the thickness of the wafer 90 held on the chuck table 31 positioned at the first grinding position below the first grinding mechanism 50. The thickness measurement gauge (second thickness measurement unit) 71 measures the thickness of the wafer 90 held on the chuck table 31 positioned at the second grinding position below the second grinding mechanism 60.

[0050] The thickness measuring gauges 70, 71 each include a reference height gauge 701, 711 that measures the height position of the holding surface 321 of the chuck table 31, and a wafer height gauge 702, 712 that measures the height position of the upper surface of the wafer 90. The reference height gauges 701, 711 are contact-type height gauges that bring a contactor into contact with the holding surface 321 and detect the height position of the holding surface 321 from the height of the contact position. Similarly, the wafer height gauges 702, 712 are contact-type height gauges that bring a contactor into contact with the upper surface of the wafer 90 and detect the height position of the upper surface of the wafer 90 from the height of the contact position. The thickness of the wafer 90 is then measured based on the difference between the measurement values ​​of the reference height gauges 701, 711 and the measurement values ​​of the wafer height gauges 702, 712.

[0051] Here, the reference height gauges 701, 711 may be fixed in order to measure the height position of the holding surface 321 of the chuck table 31, that is, may be installed in a manner that allows them to measure the height position of a predetermined position (the same, common position) of the holding surface 321 of the chuck table 31.

[0052] Alternatively, the wafer height gauges 702 and 712 may be fixedly installed so as to be able to measure the height positions of different positions (for example, different positions in the radial and circumferential directions) on the upper surface of the wafer 90. Alternatively, the wafer height gauges 702 and 712 may be movable, that is, installed so as to be movable in both the radial and circumferential directions relative to the upper surface of the substantially disk-shaped wafer 90, so as to be able to measure the height position of any point on the upper surface of the wafer 90 (so that the measurement position can be changed).

[0053] Furthermore, while Figure 1 illustrates an example in which one wafer height gauge 702, 712 is installed, two or more wafer height gauges 702, 712 may be installed in a manner that allows measurement of height positions at different positions on the top surface of the wafer 90 (for example, positions at different radial and circumferential directions) (any one of the multiple wafer height gauges may be selectively used).

[0054] The thickness measurement gauge (first thickness measurement unit) 70 and the thickness measurement gauge (second thickness measurement unit) 71 are used in the Z1 (rough grinding) / Z2 (finish grinding) small-quantity grinding technology that uses a thickness measurement machine (thickness measurement gauge). The thickness measurement machine (thickness measurement gauge) is an in-process thickness measurement device that measures the thickness of the wafer during processing and controls the grinding wheel spindle, and it constantly monitors the thickness of the wafer during processing, making it possible to minimize thickness variations between multiple wafers.

[0055] In this way, the thickness measurement gauge (first thickness measurement unit) 70 measures the thickness of the wafer (workpiece) 90 held on the holding surface 321 of the chuck table 31 positioned at the first processing position (first grinding position, rough grinding processing position). The thickness measurement gauge (second thickness measurement unit) 71 measures the thickness of the wafer (workpiece) 90 held on the holding surface 321 of the chuck table 31 positioned at the second processing position (second grinding position, finish grinding processing position).

[0056] 1 illustrates contact-type thickness gauges 70 and 71, but a non-contact type thickness gauge can also be used. The non-contact type thickness gauge has, for example, a stand erected on the outer periphery of the turntable 30, a support arm extending from the stand toward above the chuck table 31, and a sensor attached to the support arm. The sensor of the non-contact type thickness gauge measures the thickness of the wafer 90 by irradiating the wafer 90 with laser light from above. The non-contact type thickness gauge measures the thickness of the wafer 90 by receiving, with the sensor, upper surface reflected light of the laser light reflected from the upper surface of the wafer 90 and lower surface reflected light of the laser light reflected from the lower surface of the wafer 90, and measures the thickness of the wafer 90 by a spectral interference method using the principle that the upper surface reflected light and the lower surface reflected light interfere with each other.

[0057] As shown in FIGS. 3 to 6 , each chuck table 31 includes a cylindrical chuck spindle 312 centered on a central axis 311 below the porous member 32. The tilt of the chuck spindle 312 can be adjusted using the tilt adjustment mechanism 33. Specifically, the tilt of the chuck spindle 312 is adjusted using the tilt adjustment mechanism 33 so that the portion of the wafer 90, which is shaped to conform to the conical holding surface 321 and which comes into contact with the first grinding stone 51 or the second grinding stone 61, is parallel to the lower surface of the first grinding stone 51 or the lower surface of the second grinding stone 61 when viewed from the side. Alternatively, the tilt of the chuck spindle 312 is adjusted using the tilt adjustment mechanism 33 so that the portion of the wafer 90, which is shaped to conform to the conical holding surface 321 and which comes into contact with the first grinding stone 51 or the second grinding stone 61, is at a predetermined angle (tilted) relative to the lower surface of the first grinding stone 51 or the lower surface of the second grinding stone 61 when viewed from the side. In this way, by adjusting the inclination of the chuck spindle 312 by the inclination adjustment mechanism 33 before or during processing (before or during grinding), it is possible to achieve changes in the shape of the wafer due to the first and second grinding steps, as will be described later with reference to Figures 8 to 10.

[0058] The tilt adjustment mechanism 33 functions as an "angle changer" that changes the angle between the rotation axis of the first spindle 52 and the holding surface 321 of the chuck table 31 and the angle between the rotation axis of the second spindle 62 and the holding surface 321 of the chuck table 31. The tilt adjustment mechanism 33 (angle changer) changes the relative angle between the holding surface 321 of the chuck table 31 and the grinding wheels (first grinding wheel 54, second grinding wheel 64) attached to the spindles (first spindle 52, second spindle 62). The tilt adjustment mechanism 33 (angle changer) changes the relative angle between the holding surface 321 of the chuck table 31 and the rotation axes of the spindles (first spindle 52, second spindle 62).

[0059] The angle changing operation by the tilt adjustment mechanism 33 (angle changing unit) cooperates with a thickness measurement gauge (first thickness measurement unit) 70 and a thickness measurement gauge (second thickness measurement unit) 71, as will be described later with reference to Figures 8 to 10, to control (create) the shape of the wafer 90 into a characteristic shape (particularly the shape in a roughly ground state) for efficient and accurate grinding even when grinding a small amount.

[0060] The tilt adjustment mechanism 33 includes a support base 34, a position adjustment unit 35 connected to the support base 34, and a fixed support portion 36 (see FIG. 6). The support base 34 includes a cylindrical support tube portion 341 and a disk-shaped flange 342 formed by expanding the diameter of the lower portion of the support tube portion 341. The tilt adjustment mechanism 33 adjusts the tilt of the chuck spindle 312 by operating the position adjustment unit 35 to tilt the flange 342 with the fixed support portion 36 as a fulcrum.

[0061] 4, the chuck spindle 312 is inserted into the support cylinder portion 341 of the support base 34. A bearing 343 disposed inside the support cylinder portion 341 contacts the outer circumferential surface of the chuck spindle 312, and the chuck spindle 312 is rotatably supported via the bearing 343.

[0062] The position adjustment units 35 are provided at two or more locations at different positions in the circumferential direction of the support base 34, and each position adjustment unit 35 is connected to the flange 342. FIG. 5 shows an example of the arrangement of the position adjustment units 35 and the fixed support part 36. In the configuration of FIG. 5, two position adjustment units 35 and one fixed support part 36 are arranged at 120-degree intervals (equidistant intervals) in the circumferential direction. The fixed support part 36 supports the flange 342 at a constant height position. The two position adjustment units 35 can operate independently to change the height position of the flange 342.

[0063] 6, each position adjustment unit 35 includes a cylindrical portion 351 fixed to the turntable 30, a movable shaft 352 penetrating the cylindrical portion 351, a motor 353 connected to the lower end of the movable shaft 352, and a clamping nut 354 that sandwiches the flange 342 from above and below. The cylindrical portion 351 passes through a hole formed in the turntable 30 in the Z-axis direction. A threaded portion (not shown) formed on the upper end side of the movable shaft 352 passes through the flange 342 and is screwed into the clamping nut 354. When the movable shaft 352 is rotated by the motor 353, the clamping nut 354 changes its position along the movable shaft 352, and the height position of the flange 342 clamped by the clamping nut 354 changes in the Z-axis direction.

[0064] The tilt adjustment mechanism 33 is not limited to the above configuration. For example, it may be configured to have three or more position adjustment units 35 instead of two. Also, it may be configured so that the movable shaft 352 does not rotate but slides in the Z-axis direction to change the height of the flange 342.

[0065] The chuck spindle 312 is rotated by a chuck rotation unit 37. The chuck rotation unit 37 includes a motor 371, a belt pulley 372 provided on the output shaft of the motor 371, and a transmission belt 373 wound around the belt pulley 372 and the chuck spindle 312. When the belt pulley 372 is rotationally driven by the motor 371, the rotational force is transmitted to the chuck spindle 312 via the transmission belt 373. Then, the chuck spindle 312, which passes through the center (central axis 311) of the holding surface 321, rotates, causing the chuck table 31 to rotate.

[0066] 3 to 6 described above illustrate an example in which the tilt angle of the holding surface 321 of the chuck table 31 is changed without changing the tilt angle of the spindles (first spindle 52, second spindle 62). However, conversely, the tilt angle of the spindles (first spindle 52, second spindle 62) may be changed without changing the tilt angle of the holding surface 321 of the chuck table 31.

[0067] The grinding apparatus 1 is provided with a control unit 80 that controls each unit of the apparatus (see FIGS. 1 and 7). The control unit 80 is configured with a processor that executes various processes, a memory, and the like. The control unit 80 controls various operations of the grinding apparatus 1, such as transporting the wafer 90 between each unit, rough grinding with the first grinding wheel 51, finish grinding with the second grinding wheel 61, measuring the thickness of the wafer 90, and cleaning the wafer 90, according to a control program stored in the memory. The memory of the control unit 80 temporarily stores processing-related data such as the target finish thickness of the wafer 90, the amount of rough grinding for the wafer 90, the amount of finish grinding for the wafer 90, and a preset thickness tendency of the wafer 90. That is, the control unit 80 controls the grinding apparatus 1 so that the wafer (workpiece) 90 is ground (roughly ground) with the first grinding wheel 54 and then ground (finish ground) with the second grinding wheel 64.

[0068] In the following description of the operation of each part of the grinding device 1, unless a control entity is specified, it is assumed that the operation is controlled by a control signal sent from the control unit 80.

[0069] In the grinding apparatus 1 configured as described above, the tilt of the chuck table 31 is adjusted at each of the first grinding position and the second grinding position during grinding of the wafer 90. That is, the control unit 80 rotates the turntable 30, and the control unit 80 controls the tilt adjustment mechanism 33 via a first tilt control unit 81 (see FIG. 7 ) so that the chuck spindle 312 of the chuck table 31 positioned at the first grinding position is at a preset angle relative to the first spindle 52. Furthermore, the control unit 80 rotates the turntable 30, and the control unit 80 controls the tilt adjustment mechanism 33 via a second tilt control unit 82 (see FIG. 7 ) so that the chuck spindle 312 of the chuck table 31 positioned at the second grinding position is at a preset angle relative to the second spindle 62. Each operation process in the grinding apparatus 1, including the tilt adjustment of the chuck table 31, will be described below. In carrying out the present invention, not all of the work steps described below are essential, and some of the work steps may be omitted, interchanged, or replaced with other work steps.

[0070] [Holding process] The wafer 90 before grinding is taken out of the cassette 11 by the robot hand 12 and transported to the positioning mechanism 15, where the center of the wafer 90 is adjusted. Next, the loading mechanism 20 loads the wafer 90 onto the chuck table 31 at the loading / unloading position, and the wafer 90 is held on the holding surface 321.

[0071] [Thickness measurement process] After the wafer 90 is held by the chuck table 31 at the carry-in / out position, the control unit 80 rotates the turntable 30 to position the chuck table 31 at the first grinding position. Then, the control unit 80 executes a thickness measurement step using the thickness measurement gauge 70 to measure the thickness of the wafer 90 in its initial state (before grinding) at at least three locations in the radial direction.

[0072] As shown in Figures 8A, 9A, and 10A described below, a wafer 90 in its initial state (before grinding) is, for simplicity, formed into a roughly circular plate shape when viewed in a plane, and is depicted to have the same thickness over the entire area of ​​the roughly circular plate (overall area in both the radial and circumferential directions).

[0073] [Thickness trend calculation process] Next, the control unit 80 executes a thickness tendency calculation step of calculating the thickness tendency of the wafer 90 from at least three thickness values ​​measured in the thickness measurement step (performing a shape calculation of the wafer 90). For example, the height positions of the upper surface of the wafer 90 measured by the thickness measurement gauge 70 at three points near the outer periphery of the wafer 90, the middle in the radial direction, and near the center can be coordinated in the Z-axis direction, and the thickness tendency can be expressed as a curved shape that smoothly connects these three points.

[0074] [First grinding process (rough grinding process)] Next, the control unit 80 controls the first grinding process to perform grinding of the wafer 90 held on the chuck table 31 by the first grinding wheel 51 of the first grinding mechanism 50. In the first grinding process, the wafer 90 is roughly ground. In the first grinding process, the first lifting mechanism lowers the first grinding mechanism 50, and the first spindle 52 rotates the grinding wheel 54. The chuck rotation unit 37 also rotates the chuck spindle 312. The top surface of the wafer 90 is then ground by the first grinding wheel 51. When the thickness measurement gauge 70 confirms that the wafer 90 has reached the thickness and shape set for rough grinding, the rotation of the grinding wheel 54 and the rotation of the chuck spindle 312 are stopped, and the first lifting mechanism raises the first grinding mechanism 50, thereby completing the first grinding process. The measurement process using the thickness measuring gauge 70 and its relationship to the shape of the wafer before and after rough grinding will be described in detail later.

[0075] In the first grinding step (rough grinding step), a wafer grinding model for rough grinding (a grinding assist model including the shape and thickness of the wafer before and after rough grinding, a grinding assist recipe) that is set in advance and stored in memory is referenced, and a rough grinding process is performed while performing an inclination adjustment step of adjusting the inclination of the chuck spindle 312 of each chuck table 31 relative to the first spindle 52 at the first grinding position. As a result, the thickness and shape of the wafer 90 ground by the first grinding wheel 51 of the first grinding mechanism 50 are set (follow) to the thickness and shape based on the wafer grinding model for rough grinding (grinding assist model, grinding assist recipe).

[0076] [Second grinding process (finish grinding process)] Subsequently, the control unit 80 controls the second grinding mechanism 60 to perform a second grinding step in which the wafer 90 on the chuck table 31 positioned at the second grinding position is ground by the second grinding wheel 61. In the second grinding step, the wafer 90 is finish-ground.

[0077] In the second grinding step, the second elevating mechanism lowers the second grinding mechanism 60, and the second spindle 62 rotates the grinding wheel 64. Furthermore, the chuck rotator 37 rotates the chuck spindle 312 with the chuck table 31 positioned at the second grinding position. In this manner, the second grinding wheel 61 grinds the top surface of the wafer 90 while rotating the second grinding wheel 61 and the wafer 90 on the chuck table 31. When the thickness measurement gauge 71 confirms that the wafer 90 has reached the thickness and shape required for finish grinding, the rotation of the grinding wheel 64 and the rotation of the chuck spindle 312 are stopped, and the second elevating mechanism raises the second grinding mechanism 60, thereby completing the second grinding step. The relationship between the measurement process using the thickness measurement gauge 71 and the shape of the wafer before and after finish grinding will be described in detail later.

[0078] In the second grinding step (finish grinding step), a wafer grinding model for finish grinding (a grinding assist model including the shape and thickness of the wafer before and after finish grinding, a grinding assist recipe) that is set in advance and stored in memory is referenced, and a tilt adjustment step is performed to adjust the tilt of the chuck spindle 312 of each chuck table 31 relative to the second spindle 62 at the second grinding position while the finish grinding process is performed. As a result, the thickness and shape of the wafer 90 ground by the second grinding wheel 61 of the second grinding mechanism 60 are set (follow) to the thickness and shape based on the wafer grinding model for finish grinding (grinding assist model, grinding assist recipe).

[0079] [Cleaning process, removal process] Next, the control unit 80 rotates the turntable 30 to position the chuck table 31, which holds the wafer 90 ground in the second grinding step, at the carry-in / out position. Then, the carry-out mechanism 23 carries the wafer 90 out of the chuck table 31 to the cleaning mechanism 18, where the ground wafer 90 is cleaned. The cleaned wafer 90 is transported by the robot hand 12 and stored in the cassette 11.

[0080] Through the above steps, a series of operations on the wafer 90 in the grinding apparatus 1 is completed.

[0081] 7 is a block diagram conceptually showing a part of the control system of the grinding apparatus 1, including the control unit 80. The tilt adjustment of the chuck spindle 312 of each chuck table 31 at the first grinding position is controlled by a first tilt control unit 81, which is a functional block of the control unit 80. The tilt adjustment of the chuck spindle 312 of each chuck table 31 at the second grinding position is controlled by a second tilt control unit 82, which is a functional block of the control unit 80.

[0082] The first tilt control unit 81 and the second tilt control unit 82 in the control unit 80 are conceptual functional blocks, and do not mean that these units exist separately. The functions of the units in the control unit 80 are realized by the operations of the processor, memory, and the like that constitute the control unit 80.

[0083] In this embodiment, the thickness measurement gauge (first thickness measurement unit) 70 measures the height position of the wafer 90 at a predetermined position (first position) on the wafer 90 both before and after rough grinding, in other words, the grinding amount (grinding height) of the wafer 90 in rough grinding, and further the thickness of the wafer 90 after rough grinding. The thickness measurement gauge (second thickness measurement unit) 71 measures the height position of the wafer 90 at a predetermined position (second position) on the wafer 90 both before and after finish grinding, in other words, the grinding amount (grinding height) of the wafer 90 in finish grinding, and further the thickness of the wafer 90 after finish grinding. In this embodiment, the thickness measurement positions (the above-mentioned first and second positions) of the wafer 90, which is the workpiece, are different between the thickness measurement gauge (first thickness measurement unit) 70 and the thickness measurement gauge (second thickness measurement unit) 71.

[0084] The wafer 90, which is the workpiece, is formed in a substantially circular disk shape when viewed in a plan view. It is ground with different grinding amounts in the radial direction in a rough grinding process as a first process, and is ground with different grinding amounts in the radial direction in a finish grinding process as a second process. Based on this premise, a thickness measurement gauge (first thickness measurement unit) 70 measures the grinding amount both before and after the rough grinding process as the first process at a first radial position on the substantially circular wafer 90, and a thickness measurement gauge (second thickness measurement unit) 71 measures the grinding amount both before and after the finish grinding process as the second process at a second radial position on the substantially circular wafer 90. The first radial position, which is the measurement position of the thickness measurement gauge (first thickness measurement unit) 70, and the second radial position, which is the measurement position of the thickness measurement gauge (second thickness measurement unit) 71, are different from each other.

[0085] More specifically, the distance between the thickness measurement position of the thickness measurement gauge (first thickness measurement unit) 70 and the rotation axis 311 of the chuck table 31 positioned at the first processing position is set to be smaller than the distance between the thickness measurement position of the thickness measurement gauge (second thickness measurement unit) 71 and the rotation axis 311 of the chuck table 31 positioned at the second processing position. In other words, the thickness measurement gauge (first thickness measurement unit) 70 is responsible for measuring the thickness of the central portion in the radial direction of the wafer 90, which is a workpiece formed in a substantially circular plate shape when viewed in plan, and the thickness measurement gauge (second thickness measurement unit) 71 is responsible for measuring the thickness of the peripheral portion in the radial direction.

[0086] Conversely, the distance between the thickness measurement position of the thickness measurement gauge (first thickness measurement unit) 70 and the rotation axis 311 of the chuck table 31 positioned at the first processing position may be set to be larger than the distance between the thickness measurement position of the thickness measurement gauge (second thickness measurement unit) 71 and the rotation axis 311 of the chuck table 31 positioned at the second processing position. In other words, the thickness measurement gauge (first thickness measurement unit) 70 may be responsible for measuring the thickness of a peripheral portion in the radial direction of the wafer 90, which is a workpiece formed in a substantially circular plate shape when viewed in plan, and the thickness measurement gauge (second thickness measurement unit) 71 may be responsible for measuring the thickness of a central portion in the radial direction.

[0087] Furthermore, the thickness change at the first thickness measurement position in the first grinding process is set to be greater than the measurement accuracy of the thickness measurement gauge (first thickness measurement unit) 70, and the thickness change at the second thickness measurement position in the second grinding process is set to be greater than the measurement accuracy of the thickness measurement gauge (second thickness measurement unit) 71. The thickness measurement gauge (first thickness measurement unit) 70 has a minimum change amount at which a standard (constant) level of measurement accuracy is guaranteed, and the thickness change (grinding amount) at the first thickness measurement position in the first grinding process is set to exceed this minimum change amount. Similarly, the thickness measurement gauge (second thickness measurement unit) 71 has a minimum change amount at which a standard (constant) level of measurement accuracy is guaranteed, and the thickness change (grinding amount) at the second thickness measurement position in the second grinding process is set to exceed this minimum change amount.

[0088] 8A and 8B are first diagrams showing the relationship between the shape change of the wafer 90 due to the first and second grinding steps and the thickness measurement positions by the first and second thickness measuring units 70 and 71. In Fig. 8A, the top surface position of the wafer 90 before the first grinding step (rough grinding step) is depicted by a dashed line, and the top surface position of the wafer 90 after the first grinding step (rough grinding step) is depicted by a solid line. In Fig. 8B, the top surface position of the wafer 90 before the second grinding step (finish grinding step) is depicted by a dashed line, and the top surface position of the wafer 90 after the second grinding step (finish grinding step) is depicted by a solid line.

[0089] As shown in FIG. 8A , the wafer 90 before rough grinding (initial state) is formed in a substantially circular disk shape when viewed from above, and has a uniform thickness throughout the entire disk (the entire radial and circumferential areas). In the rough grinding process, the peripheral portion of the upper surface of the wafer 90 is not ground or is ground only slightly, and then the wafer 90 is ground in a conical shape from the peripheral portion toward the central axis of the wafer 90. More specifically, the angle between the rotation axis of the first spindle 52 and the holding surface 321 of the chuck table 31 is appropriately changed (controlled) by the tilt adjustment mechanism (angle change unit) 33 to match the shape of the wafer 90 after rough grinding. Here, it is advantageous to not grind the peripheral portion of the upper surface of the wafer 90 at all, rather than grinding it slightly, because this ensures the required amount of grinding (the grinding height in the axial and vertical directions).

[0090] Then, the thickness measurement gauge (first thickness measurement unit) 70 sets a first radial position closer to the central axis of the wafer 90, and measures the height position of the wafer 90 before and after rough grinding at the first radial position, in other words, the amount of grinding of the wafer 90 (grinding height) during rough grinding, and further the thickness of the wafer 90 after rough grinding. For example, the thickness measurement gauge (first thickness measurement unit) 70 may contact the wafer height gauge 702 with the top surface position 7021 of the wafer 90 at the first radial position before rough grinding, and with the wafer height gauge 702 with the top surface position 7022 of the wafer 90 at the first radial position after rough grinding, and based on the difference between these, measure the height position of the wafer 90 before and after rough grinding, in other words, the amount of grinding of the wafer 90 (grinding height) during rough grinding, and further the thickness of the wafer 90 after rough grinding.

[0091] Alternatively, the height position of the wafer 90 after rough grinding and the grinding amount (grinding height) of the wafer 90 during rough grinding may be measured (the state of the first grinding process may be detected) based on a first measurement value obtained by measuring the thickness of the wafer 90 at a first radial position (first thickness measurement position) after rough grinding using a thickness measurement gauge (first thickness measurement unit) 70 and a first set value that has been set in advance (for example, the measurement result of a reference height gauge 701 or the set value of a rough grinding auxiliary model).

[0092] 8B, in the finish grinding step, the center of the top surface of the wafer 90 is not ground or is barely ground, and grinding is performed from the center toward the periphery of the wafer 90 to remove and flatten the conical ground portion formed by rough grinding. More specifically, grinding is performed while the angle between the rotation axis of the second spindle 62 and the holding surface 321 of the chuck table 31 is appropriately changed (controlled) by the tilt adjustment mechanism (angle change unit) 33 in accordance with the shape of the wafer 90 after finish grinding.

[0093] Then, the thickness measuring gauge (second thickness measuring unit) 71 sets a second radial position farther from the central axis of the wafer 90, and measures the height position of the wafer 90 before and after finish grinding at the second radial position, in other words, the amount of grinding of the wafer 90 (grinding height) during finish grinding, and further the thickness of the wafer 90 after finish grinding. For example, the thickness measurement gauge (second thickness measurement unit) 71 may contact the wafer height gauge 712 with the top surface position 7121 of the wafer 90 at the second radial position before finish grinding, and with the wafer height gauge 712 with the top surface position 7122 of the wafer 90 at the second radial position after finish grinding, and based on the difference between these, measure the height position of the wafer 90 before and after finish grinding, in other words, the amount of grinding of the wafer 90 (grinding height) during finish grinding, and further the thickness of the wafer 90 after finish grinding.

[0094] Alternatively, the height position of the wafer 90 after finish grinding and the amount of grinding (grinding height) of the wafer 90 in finish grinding may be measured (the state of the second grinding process may be detected) based on a second measurement value obtained by measuring the thickness of the wafer 90 at a second radial position (second thickness measurement position) after finish grinding using a thickness measurement gauge (second thickness measurement unit) 71 and a second set value that has been set in advance (for example, the measurement result of the reference height gauge 711 or the set value of the finish grinding auxiliary model).

[0095] 9A and 9B are second diagrams showing the relationship between the shape change of the wafer 90 due to the first and second grinding steps and the thickness measurement positions by the first and second thickness measuring units 70 and 71. In Fig. 9A, the top surface position of the wafer 90 before the first grinding step (rough grinding step) is depicted by a dashed line, and the top surface position of the wafer 90 after the first grinding step (rough grinding step) is depicted by a solid line. In Fig. 9B, the top surface position of the wafer 90 before the second grinding step (finish grinding step) is depicted by a dashed line, and the top surface position of the wafer 90 after the second grinding step (finish grinding step) is depicted by a solid line.

[0096] As shown in FIG. 9A , the wafer 90 before rough grinding (initial state) is formed in a generally circular disk shape when viewed from above, and has a uniform thickness throughout the generally circular disk shape (the entire area in both the radial and circumferential directions). In the rough grinding process, the center of the top surface of the wafer 90 is not ground or is ground only slightly, and grinding is performed from the center toward the periphery of the wafer 90 so that a conical top surface remains. More specifically, grinding is performed while appropriately changing (controlling) the angle between the rotation axis of the first spindle 52 and the holding surface 321 of the chuck table 31 using the tilt adjustment mechanism (angle change unit) 33 in accordance with the shape of the wafer 90 after rough grinding. Here, it is advantageous to not grind the center of the top surface of the wafer 90 at all rather than grinding it slightly, as this ensures a sufficient amount of grinding (grinding height in the axial and vertical directions).

[0097] The thickness measuring gauge (first thickness measuring unit) 70 sets a first radial position farther from the central axis of the wafer 90, and measures the height position of the wafer 90 before and after rough grinding at the first radial position, in other words, the amount of grinding of the wafer 90 (grinding height) during rough grinding, and further the thickness of the wafer 90 after rough grinding. For example, the thickness measurement gauge (first thickness measurement unit) 70 may contact the wafer height gauge 702 with the top surface position 7023 of the wafer 90 at the first radial position before rough grinding, and with the wafer height gauge 702 with the top surface position 7024 of the wafer 90 at the first radial position after rough grinding, and based on the difference between these, measure the height position of the wafer 90 before and after rough grinding, in other words, the amount of grinding of the wafer 90 (grinding height) during rough grinding, and further the thickness of the wafer 90 after rough grinding.

[0098] Alternatively, the height position of the wafer 90 after rough grinding and the grinding amount (grinding height) of the wafer 90 during rough grinding may be measured (the state of the first grinding process may be detected) based on a first measurement value obtained by measuring the thickness of the wafer 90 at a first radial position (first thickness measurement position) after rough grinding using a thickness measurement gauge (first thickness measurement unit) 70 and a first set value that has been set in advance (for example, the measurement result of a reference height gauge 701 or the set value of a rough grinding auxiliary model).

[0099] 9B, in the finish grinding step, the peripheral edge of the top surface of the wafer 90 is not ground or is barely ground, and grinding is performed from the peripheral edge toward the center of the wafer 90 to remove and flatten the conical remaining portion formed by rough grinding. More specifically, grinding is performed while the angle between the rotation axis of the second spindle 62 and the holding surface 321 of the chuck table 31 is appropriately changed (controlled) by the tilt adjustment mechanism (angle change unit) 33 in accordance with the shape of the wafer 90 after finish grinding.

[0100] Then, the thickness measuring gauge (second thickness measuring unit) 71 sets a second radial position closer to the central axis of the wafer 90, and measures the height position of the wafer 90 before and after finish grinding at the second radial position, in other words, the amount of grinding of the wafer 90 (grinding height) during finish grinding, and further the thickness of the wafer 90 after finish grinding. For example, the thickness measurement gauge (second thickness measurement unit) 71 may contact the wafer height gauge 712 with the top surface position 7123 of the wafer 90 at the second radial position before finish grinding, and with the wafer height gauge 712 with the top surface position 7124 of the wafer 90 at the second radial position after finish grinding, and based on the difference between these, measure the height position of the wafer 90 before and after finish grinding, in other words, the amount of grinding of the wafer 90 (grinding height) during finish grinding, and further the thickness of the wafer 90 after finish grinding.

[0101] Alternatively, the height position of the wafer 90 after finish grinding and the amount of grinding (grinding height) of the wafer 90 in finish grinding may be measured (the state of the second grinding process may be detected) based on a second measurement value obtained by measuring the thickness of the wafer 90 at a second radial position (second thickness measurement position) after finish grinding using a thickness measurement gauge (second thickness measurement unit) 71 and a second set value that has been set in advance (for example, the measurement result of the reference height gauge 711 or the set value of the finish grinding auxiliary model).

[0102] 10A and 10B are third diagrams showing the relationship between the shape change of the wafer 90 due to the first and second grinding steps and the thickness measurement positions by the first and second thickness measuring units 70 and 71. In Fig. 10A, the top surface position of the wafer 90 before the first grinding step (rough grinding step) is depicted by a dashed line, and the top surface position of the wafer 90 after the first grinding step (rough grinding step) is depicted by a solid line. In Fig. 10B, the top surface position of the wafer 90 before the second grinding step (finish grinding step) is depicted by a dashed line, and the top surface position of the wafer 90 after the second grinding step (finish grinding step) is depicted by a solid line.

[0103] As shown in FIG. 10A , the wafer 90 before rough grinding (initial state) is formed in a generally circular disk shape in a plan view, and has a uniform thickness throughout the generally circular disk shape (the entire area in both the radial and circumferential directions). In the rough grinding process, the center and peripheral portions of the upper surface of the wafer 90 are not ground or are barely ground, and the wafer is ground into a shape that forms a thick annular groove between the center and the peripheral portion, in other words, into a generally W-shaped cross section (a shape with two recesses formed between the center and the left and right peripheral portions). More specifically, grinding is performed while appropriately changing (controlling) the angle between the rotation axis of the first spindle 52 and the holding surface 321 of the chuck table 31 using the tilt adjustment mechanism (angle change unit) 33 to match the shape of the wafer 90 after rough grinding.

[0104] The thickness measuring gauge (first thickness measuring unit) 70 sets a first radial position on the side closer to the central axis of the wafer 90 and near the deepest part of the annular groove, and measures the height position of the wafer 90 before and after rough grinding at the first radial position, in other words, the amount of grinding of the wafer 90 (grinding height) during rough grinding, and also the thickness of the wafer 90 after rough grinding. For example, the thickness measurement gauge (first thickness measurement unit) 70 may contact the wafer height gauge 702 with the top surface position 7025 of the wafer 90 at the first radial position before rough grinding, and with the wafer height gauge 702 with the top surface position 7026 of the wafer 90 at the first radial position after rough grinding, and based on the difference between these, measure the height position of the wafer 90 before and after rough grinding, in other words, the amount of grinding of the wafer 90 (grinding height) during rough grinding, and further the thickness of the wafer 90 after rough grinding.

[0105] Alternatively, the height position of the wafer 90 after rough grinding and the grinding amount (grinding height) of the wafer 90 during rough grinding may be measured (the state of the first grinding process may be detected) based on a first measurement value obtained by measuring the thickness of the wafer 90 at a first radial position (first thickness measurement position) after rough grinding using a thickness measurement gauge (first thickness measurement unit) 70 and a first set value that has been set in advance (for example, the measurement result of a reference height gauge 701 or the set value of a rough grinding auxiliary model).

[0106] 10B, in the finish grinding step, grinding is performed starting from the center and peripheral edge of the upper surface of the wafer 90, while removing the annular groove formed in the rough grinding to flatten the surface. More specifically, grinding is performed while appropriately changing (controlling) the angle between the rotation axis of the second spindle 62 and the holding surface 321 of the chuck table 31 using the tilt adjustment mechanism (angle change unit) 33 in accordance with the shape of the wafer 90 after finish grinding.

[0107] The thickness measuring gauge (second thickness measuring unit) 71 sets a second radial position on the side farther from the central axis of the wafer 90 and near the outer periphery of the annular groove, and measures the height position of the wafer 90 before and after finish grinding at the second radial position, in other words, the amount of grinding of the wafer 90 (grinding height) during finish grinding, and further the thickness of the wafer 90 after finish grinding. For example, the thickness measurement gauge (second thickness measurement unit) 71 may contact the wafer height gauge 712 with the top surface position 7125 of the wafer 90 at the second radial position before finish grinding, and with the wafer height gauge 712 with the top surface position 7126 of the wafer 90 at the second radial position after finish grinding, and based on the difference between these, measure the height position of the wafer 90 before and after finish grinding, in other words, the amount of grinding of the wafer 90 (grinding height) during finish grinding, and further the thickness of the wafer 90 after finish grinding.

[0108] 10A and 10B, when grinding is performed in the rough grinding step to grind a wafer into a generally W-shaped cross section (a shape in which two recesses are formed between the center and the left and right peripheral portions) and grinding is performed in the finish grinding step to remove the remaining material from the generally W-shaped cross section, the radial position for measurement in the finish grinding may be closer to the center than in the rough grinding. More specifically, the thickness measurement gauge (second thickness measurement unit) 71 may set a second radial position closer to the central axis of the wafer 90 and near the inner periphery (center) of the annular groove, and measure the height position of the wafer 90 before and after the finish grinding, in other words, the grinding amount (grinding height) of the wafer 90 in the finish grinding, and further the thickness of the wafer 90 after the finish grinding, at the second radial position.

[0109] Furthermore, the height position of the wafer 90 after finish grinding and the grinding amount (grinding height) of the wafer 90 in finish grinding may be measured (the state of the second grinding process may be detected) based on a second measurement value obtained by measuring the thickness of the wafer 90 at a second radial position (second thickness measurement position) after finish grinding using the thickness measurement gauge (second thickness measurement unit) 71 and a second set value that has been set in advance (for example, the measurement result of the reference height gauge 711 or the set value of the finish grinding auxiliary model).

[0110] The recommended position of the measurement point on the first axis (thickness measurement gauge (first thickness measurement unit) 70) in FIG. 8A described above is preferably, for example, approximately 30 mm to 40 mm from the center. This is because it is advantageous to ensure a measurement position close to the center without interfering with the spindle cover, wheel, etc. Furthermore, the recommended position of the measurement point on the second axis (thickness measurement gauge (second thickness measurement unit) 71) in FIG. 8B described above is preferably, for example, approximately 10 mm to 20 mm from the outer periphery. This is because it is advantageous to ensure a measurement position that is inside the porous barrier of the chuck table and as close to the outside as possible. Here, the porous barrier refers to the outer periphery of the base that stores the porous barrier of the chuck table. The porous barrier cannot adsorb the workpiece, and the workpiece is prone to flapping, making thickness measurement difficult. Therefore, it is preferable to ensure an assumed position as close to the outside as possible, avoiding the porous barrier.

[0111] The recommended position of the measurement point on the first axis (thickness measurement gauge (first thickness measurement unit) 70) in the above-mentioned FIG. 9A is preferably, for example, about 10 mm to 20 mm from the outer periphery. This is because it is advantageous to ensure a measurement position that is inside the porous barrier of the chuck table and as close to the outside as possible. Furthermore, the recommended position of the measurement point on the second axis (thickness measurement gauge (second thickness measurement unit) 71) in the above-mentioned FIG. 9B is preferably, for example, about 30 mm to 40 mm from the center. This is because it is advantageous to ensure a measurement position that does not interfere with the spindle cover, wheel, etc. and is close to the center.

[0112] In this way, when grinding extensively near the center of the wafer 90, it is preferable to set the recommended position of the measurement point by the thickness measurement gauge (thickness measurement unit) to a position about 30 mm to 40 mm from the center, and when grinding extensively near the periphery of the wafer 90, it is preferable to set the recommended position of the measurement point by the thickness measurement gauge (thickness measurement unit) to a position about 10 mm to 20 mm from the periphery.

[0113] The recommended position of the measurement point on the first axis (thickness measurement gauge (first thickness measurement unit) 70) in the above-mentioned FIG. 10A is preferably near the radial center (bottom of the recess) of the roughly W-shaped cross section (a shape with two recesses formed between the center and the left and right peripheral parts). Also, the recommended position of the measurement point on the second axis (thickness measurement gauge (second thickness measurement unit) 71) in the above-mentioned FIG. 10B is preferably about 30 mm to 40 mm from the center or about 10 mm to 20 mm from the outer periphery (on the outer periphery away from the bottom of the recesses). Thus, when grinding the two recesses having a generally W-shape cross section toward the center, the recommended position for the measurement point by the thickness measurement gauge (thickness measurement unit) is set near the radial center of the generally W-shape cross section (the bottom of the recesses), and when grinding the two recesses having a generally W-shape cross section toward the periphery, the recommended position for the measurement point by the thickness measurement gauge (thickness measurement unit) is preferably set approximately 30 to 40 mm from the center or approximately 10 to 20 mm from the periphery (the inner or outer periphery far from the bottom of the recesses). This allows for optimal measurements to be made on the first axis (thickness measurement gauge (first thickness measurement unit) 70) and the second axis (thickness measurement gauge (second thickness measurement unit) 71).

[0114] 8A, 9A, and 10A or finish grinding in Figures 8B, 9B, and 10B, grinding is performed while appropriately changing (controlling) the angle between the rotation axis of the first spindle 52 and the holding surface 321 of the chuck table 31 using the tilt adjustment mechanism (angle change unit) 33 in accordance with the shape of the wafer 90 after rough grinding or finish grinding. At this time, the angle change by the tilt adjustment mechanism 33 may be performed appropriately during processing (during grinding) (may be changed dynamically), or may be performed before processing (before grinding) and not performed during processing (during grinding).

[0115] 8A, 9A, and 10A or the finish grinding shown in FIGS. 8B, 9B, and 10B, measurements using the thickness measurement gauge (first thickness measurement unit) 70 and the thickness measurement gauge (second thickness measurement unit) 71 may be performed only before and after processing (before and after grinding), or may be performed continuously during processing (during grinding). If measurements are continued during processing (during grinding), it becomes possible to take measures (flexible responses), such as immediately stopping processing (grinding) when an abnormal value is observed in the measurement value.

[0116] In the above-mentioned Figures 8 to 10, the measurement results by the thickness measurement gauge (first thickness measurement unit) 70 and the thickness measurement gauge (second thickness measurement unit) 71 may be called, for example, the "grinding amount on the gauge locus" or the "grinding amount required to ensure gauge detection accuracy."

[0117] 8B and 10B described above, finish grinding is performed by bringing the second grinding stone 61 of the second grinding wheel 64 of the second grinding mechanism 60 into contact with the upper surface of the wafer 90. At this time, the second grinding stone 61 performs finish grinding while colliding with the edge of the upper surface of the wafer 90 (the remaining surface portion on the outer periphery in FIG. 8B, and the remaining surface portions on the inner and outer periphery in FIG. 10B), so that the second grinding stone 61 does not slip away and is securely in contact with the upper surface of the wafer 90, allowing for efficient finish grinding.

[0118] The plate-shaped workpiece manufacturing method of this embodiment can be expressed as follows. That is, the plate-shaped workpiece manufacturing method of this embodiment has a first processing step and a second processing step. In the first processing step, a disk-shaped first grinding wheel 54 having a grinding stone 51 is rotated in the circumferential direction by the first spindle 52 and brought close by the first grinding feed unit to a plate-shaped workpiece 90 held on the holding surface 321 of the chuck table 31 positioned at a first processing position by the chuck table moving unit 30, thereby processing the workpiece 90. In the second processing step, a disk-shaped second grinding wheel 64 having a grinding stone 61 is rotated in the circumferential direction by the second spindle 62 and brought close by the second grinding feed unit to a workpiece 90 ground in the first processing step and held on the holding surface 321 of the chuck table 31 positioned at a second processing position by the chuck table moving unit 30, thereby processing the workpiece 90. The first processing step includes a first grinding step of grinding the workpiece 90 and a first thickness measurement step of detecting the state of the first grinding step based on a first measurement value obtained by measuring the thickness of the workpiece 90 at a first thickness measurement position by the first thickness measurement unit 70 and a first set value that has been set in advance. The second processing step includes a second grinding step of grinding the workpiece 90 and a second thickness measurement step of detecting the state of the second grinding step based on a second measurement value obtained by measuring the thickness of the workpiece 90 at a second thickness measurement position by the second thickness measurement unit 71 and a second set value that has been set in advance. The first thickness measurement position by the first thickness measurement unit 70 and the second thickness measurement position by the second thickness measurement unit 71 are different from each other.

[0119] As described above, in the grinding apparatus and the method for manufacturing a plate-shaped workpiece according to this embodiment, the thickness measurement position of the wafer 90, which is a plate-shaped workpiece, by the thickness measurement gauge (first thickness measurement unit) 70 in the rough grinding step (first processing step) is different from the thickness measurement position of the thickness measurement gauge (second thickness measurement unit) 71 in the finish grinding step (second processing step). This makes it possible to realize a grinding apparatus and a method for manufacturing a plate-shaped workpiece that can grind efficiently and accurately even in small amounts. For example, the number of wafers that can be extracted from one ingot can be increased compared to conventional methods.

[0120] Here, the term "small amount of grinding" may refer to, for example, grinding in which the total amount of grinding of the wafer in the rough grinding process (first processing process) and the finish grinding process (second processing process) is 10 μm or less. In this case, the amount of change (grinding amount) at which the accuracy of the first and second thickness measuring units (thickness measuring gauges) is achieved may be, for example, about 3 μm or more. Furthermore, assuming that the deflection correction value of the device is measured during grinding, a wafer grinding amount of, for example, about 5 μm or more may be required.

[0121] In this way, if the thickness of the part to be measured (the amount of grinding) is too small, the thickness measuring unit that measures the thickness of the wafer during the wafer grinding process (rough grinding, finish grinding) does not have enough precision to obtain sufficient (satisfactory) measurement results. On the other hand, there is also a limit to the wafer thickness that can be measured with one thickness measuring unit.

[0122] It was common technical knowledge that conventional grinding machines measure the thickness at the same position (common position) on the top surface of the wafer during the rough grinding process (first processing process) and the finish grinding process (second processing process). However, in this case, in addition to the technical issues mentioned above, the rigidity of the grinding machine and the accuracy fluctuations (hysteresis) of the thickness measurement gauge affect the measurement, making it difficult to perform high-precision thickness measurements and ultimately the grinding process.

[0123] In this regard, in this embodiment, the shape of the wafer after rough grinding and before finish grinding is devised (a shape ground with different grinding amounts in the radial direction as illustrated in Figures 8-10 above), and the measurement positions for measuring the thickness change before and after rough grinding and the measurement positions for measuring the thickness change before and after finish grinding are set at different radial positions so that the accuracy of each thickness measurement gauge is optimized. Then, based on the thickness change before and after rough grinding and the thickness change before and after finish grinding measured at different radial positions, grinding control of the wafer, which is the workpiece, is performed. This reduces the effects of the rigidity of the grinding machine and the accuracy fluctuations (hysteresis) of the thickness measurement gauge, making it possible to perform high-precision thickness measurement and ultimately grinding processing.

[0124] The above embodiment is a two-spindle machine having two spindles that are fitted with a disk-shaped grinding wheel having a grinding stone (grinding stone) and rotate the grinding wheel in the circumferential direction. Furthermore, in the small-volume grinding targeted in this embodiment, it is preferable to use finishing stones (grinding stones with a relatively small grain size) on both axes of the first and second grinding wheels (first and second grinding stones), and it is preferable to set the grain sizes or average grain sizes of the abrasive grains contained in the first and second grinding wheels (first and second grinding stones) to be the same or different within this small grain size range.

[0125] More specifically, the particle size of the abrasive grains in the grinding stones used as finishing stones is preferably set as follows: That is, the average particle size of the abrasive grains contained in the grinding stones (first and second grinding stones) of the first and second grinding wheels is preferably 4.0 μm or less, more preferably 2.0 μm or less, and even more preferably 1.0 μm or less. In small-volume grinding, since the amount of grinding is small, it is preferable to use a grinding stone with abrasive grains of an average particle size of 4.0 μm or less to improve the finish of the ground surface.

[0126] Even if the grinding wheels (grinding stones) are of the same size (grain size), using both axes (working together) on a two-spindle machine can improve processing efficiency for the following reasons. For example, if a specified amount of material is ground using each axis of a two-spindle machine (a single axis in that sense), grinding is completed on both axes simultaneously, so if there is only one cleaning mechanism, there will be a wait time for cleaning one workpiece. In contrast, if both axes are used (working together) to grind, the specified amount of material is ground on each axis (for example, grinding half at a time). As a result, processing is completed one workpiece at a time, so even if there is only one cleaning mechanism, there is no wait time for cleaning, making continuous processing possible (reducing takt time).

[0127] The above embodiment has been described by exemplifying a two-spindle machine having two spindles on which a disc-shaped grinding wheel having a grinding stone (grinding wheel) is mounted and which rotates the grinding wheel in a circumferential direction. However, the present invention can also be applied to a single-spindle machine having one spindle on which a disc-shaped grinding wheel having a grinding stone (grinding wheel) is mounted and which rotates the grinding wheel in a circumferential direction.

[0128] The grinding device in the form of a single-spindle machine includes a chuck table 31 having a holding surface 321 for holding a plate-shaped workpiece 90 and rotating around a central axis 311 that intersects with the holding surface 321 as a rotation axis, a spindle (common spindle) to which a disk-shaped grinding wheel (54, 64) having a grinding stone (51, 61) is (selectively) attached and which rotates the grinding wheel (54, 64) in a circumferential direction, a grinding feed unit that moves the chuck table 31 and the spindle (common spindle) relatively in directions toward or away from each other, thickness measurement units (70, 71) that measure the thickness of the workpiece 90 held on the holding surface 321 of the chuck table 31, and an angle change unit 33 that changes the relative angle between the holding surface 321 of the chuck table 31 and the grinding wheel (54, 64) attached to the spindle (common spindle). Then, the thickness measuring unit (70, 71) measures the thickness of the workpiece 90 held on the holding surface 321 of the chuck table 31 at a first measurement position (first radial position) and a second measurement position (second radial position) different from the first measurement position.

[0129] The plate-shaped workpiece manufacturing method in the single-spindle machine embodiment includes a first processing step, a wheel changing step, an angle changing step, and a second processing step. In the first processing step, a disk-shaped first grinding wheel 54 having a grinding stone 51 is rotated in the circumferential direction by a spindle (common spindle) while being brought close by a grinding feed unit to process the plate-shaped workpiece 90 held on a holding surface 321 of a chuck table 31. In the wheel changing step, the first grinding wheel 54 attached to the spindle (common spindle) is replaced with a disk-shaped second grinding wheel 64 having a grinding stone 61. In the angle changing step, the angle changing unit 33 changes the relative angle between the holding surface 321 of the chuck table 31 and the rotation axis of the spindle (common spindle). In the second machining step, the second grinding wheel 64 is rotated in the circumferential direction by a spindle (a common spindle) and brought close by a grinding feed unit to machine the workpiece 90, which is held on the holding surface 321 of the chuck table 31 and ground in the first machining step. The first machining step includes a first grinding step in which the workpiece 90 is ground, and a first thickness measurement step in which the thickness measurement unit 70 measures the thickness of the workpiece 90 at a first thickness measurement position (first radial position) and the condition of the workpiece 90 is detected based on a first measurement value obtained by measuring the thickness of the workpiece 90 at a first thickness measurement position (first radial position) and a first preset value. The second machining step includes a second grinding step in which the workpiece 90 is ground, and a second thickness measurement step in which the thickness measurement unit 71 measures the thickness of the workpiece 90 at a second thickness measurement position (second radial position) and the condition of the workpiece 90 is detected based on a second measurement value obtained by measuring the thickness of the workpiece 90 at a second thickness measurement position (second radial position) and a second preset value. The first thickness measurement position (first radial position) by the thickness measurement unit 70 and the second thickness measurement position (second radial position) by the thickness measurement unit 71 are different from each other.

[0130] The embodiments of the present invention are not limited to the above-described embodiments and modifications, and may be variously changed, substituted, or modified without departing from the spirit of the technical idea of ​​the present invention. Furthermore, if the technical idea of ​​the present invention can be realized in a different way due to technological advances or other derived technologies, it may be implemented using that method. Therefore, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial Applicability]

[0131] As described above, the present invention is applicable to a grinding apparatus and a plate-shaped product manufacturing method in which, for example, plate-shaped wafers (as-sliced ​​wafers) are cut out from an ingot using a wire saw or the like, and then the wafers are ground (rough grinding, finish grinding) to remove waviness and irregularities on the surface. [Explanation of symbols]

[0132] 1: Grinding equipment 30: Turntable (chuck table moving part) 31: Chuck table 311: Central axis (rotation axis) 321: Holding surface 33: Tilt adjustment mechanism (angle change part) 50: First grinding mechanism 51: First grinding wheel (grinding wheel) 52: First spindle 54: Grinding wheel (first grinding wheel) 59: Motor (first motor) 60: Second grinding mechanism 62: Second spindle 61: Second grinding wheel (grinding wheel) 64: Grinding wheel (second grinding wheel) 69: Motor (second motor) 70: Thickness measurement gauge (first thickness measurement section) 701: Reference height gauge 702: Wafer height gauge 71: Thickness measurement gauge (second thickness measurement section) 711: Reference height gauge 712: Wafer height gauge 80: Control unit 90: Wafer (workpiece, plate-shaped object)

Claims

1. a chuck table having a holding surface for holding a plate-shaped workpiece and rotating about an axis intersecting the holding surface; a first spindle on which a disk-shaped first grinding wheel having a grinding stone is mounted and which rotates the first grinding wheel in a circumferential direction; a second spindle on which a disk-shaped second grinding wheel having a grinding stone is mounted and which rotates the second grinding wheel in a circumferential direction; a chuck table moving unit that positions the chuck table at a first processing position where the first grinding wheel attached to the first spindle can grind the workpiece held on the holding surface, and at a second processing position where the second grinding wheel attached to the second spindle can grind the workpiece held on the holding surface; a first grinding feed unit having a first motor that moves the chuck table and the first spindle relatively in directions toward or away from each other; a second grinding feed unit having a second motor that moves the chuck table and the second spindle relatively in directions toward or away from each other; a first thickness measuring unit that measures the thickness of the workpiece held on the holding surface of the chuck table positioned at the first processing position; a second thickness measuring unit that measures the thickness of the workpiece held on the holding surface of the chuck table positioned at the second processing position; Equipped with The thickness measurement position of the workpiece is different between the first thickness measurement unit and the second thickness measurement unit. A grinding device characterized by:

2. an angle formed between the rotation axis of the first spindle and the holding surface of the chuck table is different from an angle formed between the rotation axis of the second spindle and the holding surface of the chuck table; 2. The grinding device according to claim 1.

3. a distance between a thickness measurement position of the first thickness measurement unit and the rotation axis of the chuck table positioned at the first processing position is shorter than a distance between a thickness measurement position of the second thickness measurement unit and the rotation axis of the chuck table positioned at the second processing position; 3. The grinding device according to claim 1 or 2.

4. the workpiece is formed in a substantially circular disk shape when viewed from above, and is ground with different grinding amounts in the radial direction in a rough grinding process as a first process, and is ground with different grinding amounts in the radial direction in a finish grinding process as a second process, the first thickness measuring unit measures the grinding amount at a first radial position of the substantially disk-shaped workpiece before and after the rough grinding process as the first processing; the second thickness measuring unit measures the grinding amount at a second radial position of the substantially disk-shaped workpiece before and after the finish grinding process as the second processing; the first radial position and the second radial position are different from each other; 3. The grinding device according to claim 1 or 2.

5. a chuck table having a holding surface for holding a plate-shaped workpiece and rotating about an axis intersecting the holding surface; a spindle on which a disc-shaped grinding wheel having a grinding stone is mounted and which rotates the grinding wheel in a circumferential direction; a grinding feed unit that moves the chuck table and the spindle relatively in directions toward or away from each other; a thickness measuring unit for measuring the thickness of the workpiece held on the holding surface of the chuck table; an angle changing unit that changes a relative angle between the holding surface of the chuck table and the grinding wheel attached to the spindle; Equipped with the thickness measuring unit measures the thickness of the workpiece held on the holding surface of the chuck table at a first measurement position and a second measurement position different from the first measurement position. A grinding device characterized by:

6. a first processing step in which a disk-shaped first grinding wheel having a grinding stone is brought close to a plate-shaped workpiece held on a holding surface of a chuck table positioned at a first processing position by a chuck table moving unit while being rotated in a circumferential direction by a first spindle, by a first grinding feed unit, thereby processing the workpiece; a second processing step in which a second grinding wheel having a disc shape and a grinding stone is brought close to the workpiece ground in the first processing step, the workpiece being held on the holding surface of the chuck table positioned at a second processing position by the chuck table moving unit, while being rotated in a circumferential direction by a second spindle, by a second grinding feed unit, thereby processing the workpiece; Equipped with The first processing step includes: a first grinding step of grinding the workpiece; a first thickness measurement step of detecting a state of the first grinding step based on a first measurement value obtained by measuring the thickness of the workpiece at a first thickness measurement position by a first thickness measurement unit and a first set value that is set in advance; and The second processing step includes: a second grinding step of grinding the workpiece; a second thickness measuring step of detecting a state of the second grinding step based on a second measurement value obtained by measuring the thickness of the workpiece at a second thickness measurement position by a second thickness measuring unit and a second preset value; and The first thickness measurement position and the second thickness measurement position are different. A method for manufacturing a plate-like object.

7. a first processing step in which a disk-shaped first grinding wheel having a grinding stone is rotated in a circumferential direction by a spindle while being moved close to a plate-shaped workpiece held on a holding surface of a chuck table, thereby processing the workpiece; a wheel changing step of changing the first grinding wheel attached to the spindle with a disk-shaped second grinding wheel having a grinding stone; an angle changing step of changing a relative angle between the holding surface of the chuck table and the rotation axis of the spindle by an angle changing unit; a second processing step in which the second grinding wheel is rotated in a circumferential direction by the spindle while being moved close to the workpiece ground in the first processing step and held on the holding surface of the chuck table, thereby processing the workpiece; Equipped with The first processing step includes: a first grinding step of grinding the workpiece; a first thickness measurement step of detecting a state of the workpiece based on a first measurement value obtained by measuring the thickness of the workpiece at a first thickness measurement position by a thickness measurement unit and a first set value that is set in advance; and The second processing step includes: a second grinding step of grinding the workpiece; a second thickness measurement step of detecting a state of the workpiece based on a second measurement value obtained by measuring the thickness of the workpiece at a second thickness measurement position by the thickness measurement unit and a second preset value; and The first thickness measurement position and the second thickness measurement position are different. A method for manufacturing a plate-like object.

8. a change in thickness at the first thickness measurement position in the first grinding step is greater than the measurement accuracy of the thickness measurement unit or the first thickness measurement unit at the first thickness measurement position; The thickness change at the second thickness measurement position in the second grinding process is greater than the measurement accuracy of the thickness measurement unit or the second thickness measurement unit at the second thickness measurement position.

8. The method for manufacturing a plate-like product according to claim 6 or 7.

9. The average particle size of the abrasive grains contained in the grinding stones of the first grinding wheel and the second grinding wheel is 4.0 μm or less.

8. The method for manufacturing a plate-like product according to claim 6 or 7.

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