Grinding apparatus, method of grinding workpiece, method of manufacturing ground workpiece, and method of manufacturing chip

Abstract

To highly accurately and uniformly grind a workpiece to a predetermined thickness while adjusting machining conditions.SOLUTION: A grinding device for grinding a workpiece comprises a chuck table rotatable around a table rotating shaft, a grinding unit provided with a spindle having a grinding wheel mounted on the lower end thereof and having a grinding stone annularly arranged on the lower surface thereof, a tilt adjusting unit for adjusting the tilt of one or both of the table rotating shaft and the spindle, a thickness measuring device for measuring the thickness of the workpiece, and a controller, and the controller comprises a required adjustment amount calculating section for acquiring thickness information of the workpiece being ground by the grinding unit by using the thickness measuring unit and calculating, as a required adjustment amount, an adjustment amount required for adjustment of the tilt performed by the tilt adjusting unit on the basis of the thickness information, an actual adjustment amount calculating section for calculating an actual adjustment amount by multiplying the required adjustment amount by an adjustment rate, and an adjustment control section for controlling the tilt adjusting unit to adjust the tilt by the actual adjustment amount.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a grinding device that holds a workpiece such as a semiconductor wafer on a chuck table and grinds the workpiece held on the chuck table to thin it, a grinding method for grinding the workpiece with the grinding device, a method for manufacturing the ground workpiece, and a method for manufacturing chips by grinding and dividing the workpiece. [Background technology]

[0002] Device chips equipped with ICs (Integrated circuits), LSIs (Large Scale Integration), and other devices are manufactured from disk-shaped wafers. Multiple devices are formed on the front surface of the wafer, which is then thinned by grinding from the backside and divided into individual device chips.

[0003] Grinding of workpieces such as wafers is performed by a grinding device (see Patent Document 1). The grinding device has a chuck table that holds the workpiece, and a grinding unit that grinds the workpiece held by the chuck table. The grinding unit includes a grinding wheel to which grinding stones are fixed and arranged in a ring shape in a plane approximately parallel to the holding surface of the chuck table, and a spindle that serves as the rotation axis when rotating the grinding wheel.

[0004] The grinding device can rotate the chuck table around a table rotation axis that passes through the center of the holding surface, and can rotate the grinding wheel around the spindle to rotate the grinding stone on a circular orbit. When the chuck table and grinding wheel (spindle) are rotated and the grinding unit is lowered to bring the rotating grinding stone into contact with the workpiece, the workpiece is ground.

[0005] To obtain a workpiece that is thinned to a predetermined thickness with high precision and has a uniform thickness at each point, the grinding machine uses a thickness gauge to monitor the thickness of each point of the workpiece being ground (see Patent Document 2).Then, based on information about the thickness of each point of the workpiece, the tilt of the table rotation axis, spindle, etc. are adjusted. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-141176 [Patent Document 2] Japanese Patent Publication No. 2022-133006 Summary of the Invention [Problem to be solved by the invention]

[0007] It takes a certain amount of time for the effect of an adjustment, such as an adjustment of the tilt of the table rotation axis, to be reflected in the thickness distribution of the workpiece. If the tilt of the table rotation axis is readjusted during this transitional period, the adjustment amount is likely to be excessive, making it difficult to achieve a uniform thickness distribution of the workpiece. Furthermore, excessive adjustments and excessive corrections of the excessive adjustments are repeated, resulting in repeated rapid and slow decreases in the thickness of the workpiece during grinding. When the processing conditions and processing become unstable in this way, it is difficult to obtain stable processing results.

[0008] On the other hand, if the next adjustment is delayed until the effect of each adjustment is reflected in the thickness distribution of the workpiece, the number of adjustments that can be made during grinding of the workpiece will decrease, making it impossible to make adjustments that correspond to the constantly changing machining conditions, resulting in greater variability in the machining results.

[0009] The present invention has been made in consideration of such problems, and its object is to provide a grinding device that can grind a workpiece to a predetermined thickness with high precision and uniformity by appropriately adjusting the processing conditions while grinding the workpiece, a method for grinding a workpiece, a method for manufacturing a ground workpiece, and a method for manufacturing chips by grinding and dividing the workpiece. [Means for solving the problem]

[0010] According to one aspect of the present invention, a grinding device for grinding a workpiece includes a chuck table having a holding surface capable of holding the workpiece and rotatable about a table rotation axis passing through the center of the holding surface, and a spindle having a grinding wheel with annularly arranged grinding stones on its underside attached to its lower end so that the underside of the grinding wheel faces the holding surface of the chuck table, the grinding device further includes a grinding unit for grinding the workpiece held by the chuck table with the grinding stones of the grinding wheel, an elevation mechanism for relatively raising and lowering the spindle and the chuck table, an inclination adjustment unit for adjusting the inclination of one or both of the table rotation axis and the spindle, a thickness gauge for measuring the thickness of the workpiece held by the chuck table, and a controller, wherein the controller controls the chuck table for holding the workpiece, a grinding control unit that rotates a grinding wheel of the grinding unit around the spindle while using the lifting mechanism to bring the spindle and the chuck table closer to each other and bring the grinding stone into contact with the workpiece held by the chuck table, thereby causing the grinding unit to grind the workpiece; a required adjustment amount calculation unit that uses the thickness measuring device to obtain thickness information of the workpiece being ground by the grinding unit and calculates, based on the thickness information, an adjustment amount required for adjusting the inclination to be performed by the inclination adjustment unit as a required adjustment amount; an actual adjustment amount calculation unit that multiplies the required adjustment amount calculated by the required adjustment amount calculation unit by an adjustment rate to calculate an actual adjustment amount; and an adjustment control unit that controls the inclination adjustment unit to adjust the inclination by the actual adjustment amount calculated by the actual adjustment amount calculation unit.

[0011] Preferably, the necessary adjustment amount calculation unit calculates the necessary adjustment amount so as to PID control the slope based on the thickness information.

[0012] Alternatively, preferably, the necessary adjustment amount calculation section calculates the necessary adjustment amount based on the thickness information so as to P-control the inclination.

[0013] Preferably, the actual adjustment amount calculation section determines the adjustment rate based on the thickness information or the required adjustment amount.

[0014] More preferably, the actual adjustment amount calculation unit sets the adjustment rate to a first adjustment rate when the thickness information or the value indicating the required adjustment amount is higher than a selection threshold, and sets the adjustment rate to a second adjustment rate smaller than the first adjustment rate when the value is equal to or lower than the selection threshold.

[0015] According to another aspect of the present invention, there is provided a grinding method for grinding a workpiece in a grinding apparatus including a chuck table having a holding surface capable of holding a workpiece and rotatable about a table rotation axis passing through the center of the holding surface, and a grinding unit including a spindle having a grinding wheel attached to its lower end, the grinding wheel having grinding stones arranged in an annular pattern on its lower surface, the method comprising the steps of: placing the workpiece on the holding surface of the chuck table and holding the workpiece with the chuck table; and rotating the chuck table about the table rotation axis after the holding step. and a grinding step of rotating the spindle together with the table rotation axis and moving the chuck table and the spindle relatively in directions in which they approach each other, thereby bringing the grinding wheel into contact with the workpiece and grinding the workpiece, wherein in the grinding step, thickness information of the workpiece being ground is obtained, an adjustment amount required to adjust the inclination of one or both of the table rotation axis and the spindle is calculated as a required adjustment amount based on the thickness information, an actual adjustment amount is calculated by multiplying the required adjustment amount by an adjustment rate, and the inclination is adjusted using the actual adjustment amount.

[0016] Preferably, in the grinding step, the necessary adjustment amount is calculated based on the thickness information so that the inclination can be PID controlled.

[0017] Alternatively, preferably, in the grinding step, the necessary adjustment amount is calculated based on the thickness information so that the tilt can be P-controlled.

[0018] Also preferably, in the grinding step, the adjustment rate is determined based on the thickness information or the required adjustment amount.

[0019] More preferably, in the grinding step, if the thickness information or the value indicating the required adjustment amount is higher than a selected threshold, the adjustment rate is set to a first adjustment rate, and if the value is equal to or lower than the selected threshold, the adjustment rate is set to a second adjustment rate smaller than the first adjustment rate.

[0020] According to yet another aspect of the present invention, there is provided a method for manufacturing a ground workpiece by grinding a workpiece in a grinding device including a chuck table having a holding surface capable of holding a workpiece and rotatable about a table rotation axis passing through the center of the holding surface, and a grinding unit including a spindle having a grinding wheel attached to its lower end, the grinding wheel having a circularly arranged grinding stone on its lower surface, the method including placing the workpiece on the holding surface of the chuck table and holding the workpiece with the chuck table, rotating the chuck table around the table rotation axis and rotating the spindle, and grinding the workpiece with the chuck table. and manufacturing a ground workpiece by relatively moving the table and the spindle in directions in which they approach each other and bringing the grinding wheel into contact with the workpiece to grind it, wherein when bringing the grinding wheel into contact with the workpiece to grind it, thickness information of the workpiece being ground is obtained, and an adjustment amount required to adjust the inclination of one or both of the table rotation axis and the spindle is calculated based on the thickness information, and an actual adjustment amount is calculated by multiplying the required adjustment amount by an adjustment rate, and the inclination is adjusted using the actual adjustment amount.

[0021] According to yet another aspect of the present invention, there is provided a method for manufacturing chips by grinding a workpiece in a grinding device including a chuck table having a holding surface capable of holding a workpiece and rotatable about a table rotation axis passing through the center of the holding surface, and a grinding unit including a spindle having a grinding wheel attached to its lower end, the grinding wheel having grinding stones arranged in an annular pattern on its lower surface, and dividing the workpiece to manufacture chips, the method comprising the steps of: placing the workpiece on the holding surface of the chuck table and holding it with the chuck table; rotating the chuck table around the table rotation axis and rotating the spindle; and moving the spindles relatively in directions in which they approach each other, bringing the grinding wheel into contact with the workpiece to grind it; and removing the ground workpiece from the grinding device and dividing it into individual chips, wherein when bringing the grinding wheel into contact with the workpiece to grind it, thickness information of the workpiece being ground is obtained, and an adjustment amount required to adjust the inclination of one or both of the table rotation axis and the spindle is calculated as a required adjustment amount based on the thickness information, and an actual adjustment amount is calculated by multiplying the required adjustment amount by an adjustment rate, and the inclination is adjusted using the actual adjustment amount. [Effects of the Invention]

[0022] In a grinding apparatus and a method for grinding a workpiece according to one aspect of the present invention, the inclination of one or both of a table rotation axis, which is the rotation axis of the chuck table, and a spindle to which a grinding wheel is connected, is adjusted while the workpiece is being ground with a grinding wheel. At this time, thickness information of the workpiece being ground is acquired, and the adjustment amount required to adjust this inclination is calculated as a required adjustment amount based on the thickness information. The required adjustment amount is multiplied by an adjustment rate to calculate an actual adjustment amount. The inclination is then adjusted using the actual adjustment amount.

[0023] That is, when the necessary adjustment amount for tilt adjustment is calculated, the tilt is not immediately adjusted by the necessary adjustment amount. Instead, the necessary adjustment amount is multiplied by a predetermined adjustment rate to calculate the actual adjustment amount, and the tilt is adjusted by the actual adjustment amount. In this case, an appropriate adjustment rate is selected so that the tilt can be adjusted at an appropriate speed and so that adjustment and correction are not repeated. This reduces variations in the machining results due to tilt adjustment.

[0024] Therefore, one aspect of the present invention provides a grinding device that can grind a workpiece to a predetermined thickness with high precision and uniformity by appropriately adjusting the processing conditions while grinding the workpiece, a method for grinding a workpiece, a method for manufacturing a ground workpiece, and a method for manufacturing chips that grind and divide the workpiece to manufacture chips. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 2 is a perspective view schematically showing a grinding device and a workpiece. [Figure 2] FIG. 2 is a cross-sectional view schematically showing a grinding unit and a chuck table. [Figure 3] FIG. 2 is a plan view schematically showing the positional relationship between a chuck table and a grinding wheel. [Figure 4] FIG. 4(A) is a graph that schematically shows one element of the thickness information of the workpiece, and FIG. 4(B) is a graph that schematically shows another element of the thickness information of the workpiece. [Figure 5] FIG. 5(A) is a graph showing the change in the amount of V when the adjustment rate Kp is set to 0.0, and FIG. 5(B) is a graph showing the change in the amount of V when the adjustment rate Kp is set to 0.2. [Figure 6] FIG. 6(A) is a graph showing the change in the amount of V when the adjustment rate Kp is set to 0.3, and FIG. 6(B) is a graph showing the change in the amount of V when the adjustment rate Kp is set to 0.4. [Figure 7] FIG. 7(A) is a graph showing the change in the amount of V when the adjustment rate Kp is set to 0.5, and FIG. 7(B) is a graph showing the change in the amount of V when the adjustment rate Kp is set to 1.0. [Figure 8] 10 is a graph showing the transition of the amount of V when the adjustment rate Kp is determined under comparative conditions. [Figure 9] Figure 9(A) is a graph showing the change in the amount of V when the adjustment rate Kp is determined under the first condition, and Figure 9(B) is a graph showing the change in the amount of V when the adjustment rate Kp is determined under the second condition. [Figure 10] 3 is a flowchart showing the flow of each step of a method for grinding a workpiece. [Figure 11] 1 is a flowchart showing the flow of each step of a manufacturing method for manufacturing a ground workpiece. [Figure 12] 1 is a flowchart showing the flow of each step in a chip manufacturing method. [Figure 13] FIG. 1 is a perspective view schematically showing how a workpiece is divided to produce chips. DETAILED DESCRIPTION OF THE INVENTION

[0026] An embodiment of the present invention will be described with reference to the drawings. A grinding device according to this embodiment grinds a workpiece to thin it. First, the workpiece will be described. FIG. 1 includes a perspective view schematically showing a workpiece 1.

[0027] The workpiece 1 is, for example, a substantially disk-shaped wafer made of Si, SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor material, etc. However, the workpiece 1 is not limited to these.

[0028] When a plurality of devices are arranged in a matrix on the front surface 1a of a workpiece 1 such as a disk-shaped wafer, and the workpiece 1 is divided into individual devices, individual device chips are obtained. At this time, if the workpiece 1 is previously ground from the back surface 1b side using a grinding device 2 to thin the workpiece 1, thin device chips are ultimately obtained. A tape-like protective member 3 is attached to the front surface 1a of the workpiece 1 that is ground by the grinding device 2 to protect the devices and the like formed on this front surface 1a.

[0029] Next, the grinding apparatus 2 according to this embodiment will be described in detail. The grinding apparatus 2 includes a base 4 that supports each of the components. Cassette mounts 26a and 26b are fixed to the front end of the base 4. Cassettes 28a and 28b, each containing a plurality of workpieces 1, are placed on the cassette mounts 26a and 26b. In the grinding apparatus 2, the workpieces 1 are successively drawn out of the cassettes 28a and 28b, the workpieces 1 are ground, and the ground workpieces 1 are returned to the cassettes 28a and 28b.

[0030] A wafer transfer robot 30 is installed at a position adjacent to the cassette mounting tables 26a and 26b on the base 4. The wafer transfer robot 30 takes out the workpiece 1 from the cassettes 28a and 28b placed on the cassette mounting tables 26a and 26b, and transfers the workpiece 1 to a positioning table 32 provided at a position adjacent to the wafer transfer robot 30 on the base 4.

[0031] The positioning table 32 has a plurality of positioning pins arranged in a ring shape. When the workpiece 1 is placed in the central placement area, the positioning table 32 moves each of the positioning pins radially inward in unison to position the workpiece 1 at a predetermined position.

[0032] A loading arm 34 and an unloading arm 36 are provided at positions adjacent to the positioning table 32 on the upper surface of the base 4. The workpiece 1 positioned at a predetermined position by the positioning table 32 is transported by the loading arm 34.

[0033] A disk-shaped turntable 6 is provided rotatably in a horizontal plane on the central upper surface of the base 4. Three chuck tables 8 are provided on the upper surface of the turntable 6, spaced 120 degrees apart from one another in the circumferential direction. When the turntable 6 is rotated, each chuck table 8 that holds the workpiece 1 can be moved.

[0034] 2 includes a cross-sectional view that schematically shows the chuck table 8. The chuck table 8 includes a disk-shaped porous member 8c having the same diameter as the workpiece 1, and a stainless steel frame 8b having an exposed recess on the top to accommodate the porous member 8c. The frame 8b of the chuck table 8 is provided with a suction path, one end of which reaches the bottom of the recess, and the other end of which is connected to a suction source (not shown).

[0035] When the workpiece 1 is placed on the porous member 8c of the chuck table 8 and the suction source is activated, negative pressure acts on the workpiece 1 through the suction path and the porous member 8c, and the workpiece 1 is sucked and held on the chuck table 8. In other words, the upper surface of the chuck table 8 serves as a holding surface 8a that holds the workpiece 1. As will be described later, this holding surface 8a has a very gently sloping conical surface shape.

[0036] A rotary drive source 56 such as a motor is connected to the bottom of the chuck table 8, and the chuck table 8 can rotate around a table rotation axis 58 that is set to pass through the center of the holding surface 8a.

[0037] Furthermore, the bottom 54 of the chuck table 8 is supported by multiple support shafts in a manner that does not hinder rotation, and one or more of the support shafts are extendable. For example, in the grinding device 2 according to this embodiment, the bottom 54 is supported by one fixed shaft 60 and two extendable adjustment shafts 62, 64. Adjusting the lengths of these adjustment shafts 62, 64 allows the inclination of the holding surface 8a (the inclination of the table rotation shaft 58) to be changed. In other words, the adjustment shafts 62, 64 function as an inclination adjustment unit that adjusts the inclination of the table rotation shaft 58.

[0038] 1, the explanation will be continued. The workpiece 1 is loaded onto and unloaded from the chuck table 8 in the wafer loading / unloading area of ​​the turntable 6. In the wafer loading / unloading area, the workpiece 1 can be loaded onto the chuck table 8 by a loading arm 34, and the workpiece 1 can be unloaded from the chuck table 8 by an unloading arm 36.

[0039] After the workpiece 1 is loaded by the loading arm 34 onto the chuck table 8 positioned in the wafer loading / unloading area, the turntable 6 is rotated to move the chuck table 8 to the next rough grinding area.

[0040] A first grinding unit 10a that roughly grinds the back surface 1b of the workpiece 1 held by a chuck table 8 positioned in the rough grinding area is arranged outside the turntable 6 on the upper rear surface of the base 4. After the first grinding unit 10a has performed rough grinding of the workpiece 1, the turntable 6 is rotated to move the chuck table 8 to a finish grinding area adjacent to the rough grinding area.

[0041] A second grinding unit 10b is disposed outside the turntable 6 on the upper rear surface of the base 4, and performs finish grinding on the back surface 1b of the workpiece 1 held on the chuck table 8 positioned in the finish grinding area. After the second grinding unit 10b has performed finish grinding on the workpiece 1, the turntable 6 is rotated to return the chuck table 8 to the wafer load / unload area, and the workpiece 1 is unloaded from the chuck table 8 by the unloading arm 36.

[0042] A spinner cleaning device 38 that cleans and spin-dries the ground workpiece 1 is disposed near the unloading arm 36 on the upper surface of the base 4 and the wafer transfer robot 30. The workpiece 1 that has been cleaned and dried by the spinner cleaning device 38 is then transported from the spinner cleaning device 38 by the wafer transfer robot 30 and stored in cassettes 28a and 28b placed on cassette mounting tables 26a and 26b.

[0043] Columns 22a and 22b are erected at the rear of the base 4. A first grinding unit 10a is arranged in front of the column 22a so as to be able to rise and fall, and a second grinding unit 10b is arranged in front of the column 22b so as to be able to rise and fall.

[0044] The first grinding unit 10a includes a first spindle 14a extending generally vertically and a spindle motor 12a connected to the upper end of the first spindle 14a, while the second grinding unit 10b includes a second spindle 14b extending generally vertically and a spindle motor 12b connected to the upper end of the second spindle 14b.

[0045] The first grinding unit 10a includes a first lifting mechanism 24a that supports components of the first grinding unit 10a, including the first spindle 14a, so that they can move generally vertically. The second grinding unit 10b includes a second lifting mechanism 24b that supports components of the second grinding unit 10b, including the second spindle 14b, so that they can move generally vertically.

[0046] In the grinding device 2, the orientation of each of the spindles 14a, 14b may be adjustable instead of the table rotation shaft 58. Alternatively, the orientation of each of the spindles 14a, 14b may be adjustable in addition to the table rotation shaft 58. In other words, the grinding device 2 includes an inclination adjustment unit that adjusts the inclination of one or both of the table rotation shaft 58 and the spindles 14a, 14b.

[0047] 1 and 2 show the second lifting mechanism 24b. The second lifting mechanism 24b includes a pair of guide rails 24c provided vertically in front of the column 22b, a lifting plate 50 slidably supported on the guide rails 24c, and a ball screw 44 parallel to the pair of guide rails 24c. The components of the second grinding unit 10b are supported on the front surface of the lifting plate 50.

[0048] A nut portion 46 is provided on the back side of the lifting plate 50, and this nut portion 46 is threadedly engaged with a ball screw 44. A pulse motor 48 is connected to the upper end of the ball screw 44. When this pulse motor 48 is operated, the ball screw 44 rotates, and the lifting plate 50 moves up and down. The first lifting mechanism 24a is configured similarly to the second lifting mechanism 24b.

[0049] The lifting mechanism of the grinding device 2 may lift the chuck table 8 instead of the spindles 14a, 14b, or may lift the chuck table 8 in addition to the spindles 14a, 14b. In other words, the grinding device 2 includes a lifting mechanism that lifts the spindles 14a, 14b and the chuck table 8 relatively.

[0050] A disk-shaped wheel mount 16a is disposed at the lower end of the first spindle 14a, and a first grinding wheel 18a is fixed to the lower surface of the wheel mount 16a. That is, the first grinding wheel 18a is fixed to the lower end of the first spindle 14a. A plurality of first grinding stones 20a arranged in an annular shape are attached to the surface (lower surface) of the first grinding wheel 18a that faces the holding surface 8a of the chuck table 8 positioned in the rough grinding region.

[0051] A disk-shaped wheel mount 16b is disposed at the lower end of the second spindle 14b, and a second grinding wheel 18b is fixed to the lower surface of the wheel mount 16b. That is, the second grinding wheel 18b is fixed to the lower end of the second spindle 14b. A plurality of second grinding stones 20b arranged in an annular shape are attached to the surface (lower surface) of the second grinding wheel 18b that faces the holding surface 8a of the chuck table 8 positioned in the finish grinding region.

[0052] When the spindle motor 12a is operated to rotate the first spindle 14a, the first grinding wheel 18a rotates and the first grinding stone 20a moves on the first circular track. Then, the lifting mechanism 24a is operated to lower the first spindle 14a, and the first grinding stone 20a is brought into contact with the back surface 1b (upper surface) of the workpiece 1 held on the chuck table 8, whereby the workpiece 1 is ground.

[0053] When the spindle motor 12b is operated to rotate the spindle 14b, the second grinding wheel 18b rotates and the second grinding stone 20b moves on the second circular track. Then, the lifting mechanism 24b is operated to lower the second spindle 14b, and the second grinding stone 20b is brought into contact with the back surface 1b (upper surface) of the workpiece 1 held on the chuck table 8, whereby the workpiece 1 is ground.

[0054] In the first grinding unit 10a, the workpiece 1 is roughly ground by the lifting mechanism 24a, which moves the grinding feed at a relatively high speed. In the rough grinding by the first grinding unit 10a, most of the total grinding amount is removed until the workpiece 1 reaches the finishing thickness. In the second grinding unit 10b, the workpiece 1 is finish ground by the lifting mechanism 24b, which moves the grinding feed at a relatively low speed. In the finish grinding by the second grinding unit 10b, the workpiece 1 is ground until it reaches the finishing thickness, and roughness on the back surface 1b side is removed.

[0055] The first grinding wheel 20a and the second grinding wheel 20b contain abrasive grains made of diamond or the like and a binder that disperses and fixes the abrasive grains. The second grinding wheel 20b used for finish grinding preferably contains abrasive grains with a smaller particle size than the abrasive grains contained in the first grinding wheel 20a used for rough grinding. In this case, the first grinding wheel 20a can quickly rough-grind the workpiece 1, while the second grinding wheel 20b can finish-grind the workpiece 1 with high quality.

[0056] A first thickness gauge 40 for measuring the thickness of the workpiece 1 to be rough ground by the first grinding unit 10a is disposed on the upper surface of the base 4 near the first grinding unit 10a. A second thickness gauge 42 for measuring the thickness of the workpiece 1 to be finish ground by the second grinding unit 10b is disposed on the upper surface of the base 4 near the second grinding unit 10b.

[0057] The first thickness measuring device 40 is, for example, a contact-type thickness measuring device that comes into contact with the back surface 1b of the workpiece 1. The contact-type thickness measuring device includes, for example, two probes that extend above the chuck table 8.

[0058] Each probe has a contact part extending downward from the tip of an arm extending horizontally. One probe measures the height of the back surface 1b of the workpiece 1 by bringing the bottom end of the contact part into contact with the back surface 1b of the workpiece 1. The other probe measures the height of the holding surface 8a of the chuck table 8 by bringing the bottom end of the contact part into contact with the holding surface 8a.

[0059] The workpiece 1 is placed and held on the holding surface 8a of the chuck table 8 via the protective member 3. Therefore, the contact-type thickness gauge can calculate the total thickness of the workpiece 1 and the protective member 3 from the difference between the measured height of the back surface 1b of the workpiece 1 and the height of the holding surface 8a of the chuck table 8.

[0060] Furthermore, the second thickness measuring device 42 is, for example, a non-contact type thickness measuring device that does not physically come into contact with the back surface 1b of the workpiece 1. The non-contact type thickness measuring device measures the height of the back surface 1b of the workpiece 1 by, for example, sending ultrasonic waves or probe light from a measuring unit 42a disposed directly above the back surface 1b of the workpiece 1 to the back surface 1b, receiving the reflected ultrasonic waves or the like at the measuring unit 42a, and analyzing the ultrasonic waves or the like. In this way, the measuring unit 42a is a non-contact type sensor.

[0061] The non-contact second thickness gauge 42 has, for example, a rotatable shaft 42b erected on the upper surface of the base 4 of the grinding device 2, and an arm 42c extending horizontally from the upper end of the shaft 42b, with the measuring unit 42a fixed to the tip of the arm 42c. A rotation mechanism (not shown) composed of a piston, a motor, or the like is connected to the lower end of the shaft 42b, and the rotation mechanism rotates the shaft 42b.

[0062] When the shaft 42b is rotated, the measuring unit 42a moves on an arc-shaped measurement orbit centered on the shaft 42b. That is, the grinding device 2 is provided with a measuring unit moving mechanism that moves the measuring unit 42a back and forth on the measurement orbit above the workpiece 1 held by the chuck table 8. The measuring unit 42a is movable above the back surface 1b of the workpiece 1 while the back surface 1b is being ground by the second grinding unit 10b, and can measure the thickness of various points on the back surface 1b of the workpiece 1.

[0063] However, the measuring unit 42a cannot enter a position where it will interfere with the second grinding unit 10b that grinds the workpiece 1. While the workpiece 1 is being ground, the second grinding wheel 20b is constantly in contact with the center of the workpiece 1, so there is no time when the measuring unit 42a can enter above the center of the workpiece 1. In other words, the measuring unit moving mechanism moves the measuring unit 42a back and forth on the measurement orbit between above the outer periphery of the workpiece 1 held by the chuck table 8 and above the workpiece where it does not interfere with the grinding units 10a and 10b.

[0064] The grinding apparatus 2 further includes a controller (control unit) 90 that controls each of the components. The controller 90 controls, for example, the turntable 6, the chuck table 8, the grinding units 10a and 10b, the wafer transfer robot 30, the positioning table 32, the loading arm 34, the unloading arm 36, the spinner cleaning device 38, and the like.

[0065] The controller 90 is configured by a computer including, for example, a processing device such as a CPU (Central Processing Unit) or a microprocessor, and a storage device such as a flash memory or a hard disk drive. The controller 90 operates the processing device in accordance with software such as a program stored in the storage device, thereby functioning as a concrete means in which the software and the processing device (hardware resource) work together.

[0066] The controller 90 stores in a storage device various information and the like, as well as processing conditions for grinding various types of workpieces 1 with the grinding units 10a, 10b. The processing conditions stored in the storage device include information such as the type and size of the workpiece 1 to be processed, the finishing thickness in rough grinding and finish grinding, and the rotation speed of the spindles 14a, 14b.

[0067] For example, the controller 90 includes a grinding control unit 92 that controls each component to grind the workpiece 1. When the workpiece 1 is ground, the grinding control unit 92 rotates the chuck table 8 that holds the workpiece 1 about the table rotation axis 58 and rotates the grinding wheels 18a, 18b of the grinding units 10a, 10b about the spindles 14a, 14b. The spindles 14a, 14b are then lowered by the lifting mechanisms 24a, 24b to bring the spindles 14a, 14b and the chuck table 8 closer to each other, and the grinding wheels 20a, 20b are brought into contact with the workpiece 1 held by the chuck table 8 to grind the workpiece 1.

[0068] The grinding control unit 92 controls each component in accordance with the grinding conditions stored in the controller 90. While the grinding of the workpiece 1 progresses, the grinding control unit 92 monitors the thickness of the workpiece 1 using the thickness measuring devices 40, 42, and when the workpiece 1 reaches a predetermined thickness, stops the descent of the spindles 14a, 14b and stops grinding of the workpiece 1.

[0069] As shown in Figure 2 and other figures, the holding surface 8a of the chuck table 8 is configured as an extremely gently sloping cone with its apex at the center. If the holding surface 8a is a cone, when the workpiece 1 is held by suction on the chuck table 8, the workpiece 1 will deform slightly in accordance with the holding surface 8a. Note that the shapes of the workpiece 1, chuck table 8, and the like shown in each figure are exaggerated for ease of explanation. The following explanation will be given using as an example the finish grinding performed by the second grinding unit 10b shown in Figure 2.

[0070] When grinding the workpiece 1, in this state, the chuck table 8 is rotated around the table rotation axis 58, and the second spindle 14b is lowered while rotating, so that the second grinding wheel 20b comes into contact with the back surface 1b of the workpiece 1. Then, the workpiece 1 placed on the chuck table 8 rotates while grinding progresses in an arc-shaped region from the center to the outer periphery of the workpiece 1, and the entire area of ​​the workpiece 1 is ground.

[0071] The inclination of the table rotation axis 58 is adjusted so that the generatrix constituting the holding surface 8a, which is formed by a conical surface, that is closest to the plane of rotation including the annular orbit of the second grinding wheel 20b is parallel to this plane of rotation, so that the front surface 1a and the back surface 1b of the ground workpiece 1 are parallel to this plane of rotation.Then, the thickness of the workpiece 1 is monitored by the second thickness measuring device 42, and when the workpiece 1 reaches a predetermined thickness, the lowering of the second spindle 14b by the lifting mechanism 24b is stopped, and grinding of the workpiece 1 is completed.

[0072] If the relative inclination of the table rotation axis 58 and the second spindle 14b is not appropriate, the thickness distribution of the workpiece 1 will not be uniform, resulting in thickness deviations and preventing the front surface 1a and back surface 1b of the workpiece 1 from being parallel after grinding. Therefore, while the workpiece 1 is being ground, the measuring unit 42a of the second thickness gauge 42 is moved to measure the thickness of each point of the workpiece 1. Then, the thickness distribution of the workpiece 1 is monitored, and if a problem occurs with the thickness distribution, the inclination of the table rotation axis 58, etc. can be adjusted using the inclination adjustment unit.

[0073] For example, the controller 90 includes a required adjustment amount calculation unit 94. The required adjustment amount calculation unit 94 acquires thickness information of the workpiece 1 being ground by the grinding units 10a and 10b using the thickness measuring device 42, and calculates, as the required adjustment amount, the adjustment amount required for the tilt adjustment performed by the tilt adjustment unit based on this thickness information.

[0074] The thickness information of the workpiece 1 acquired by the necessary adjustment amount calculation unit 94 using the thickness measuring device 42 is, for example, a collection of thickness values ​​at various locations on the workpiece 1. When the workpiece 1 is ground by the grinding units 10a and 10b, the thickness of the workpiece 1 is the same at each point that is the same distance from the center of the workpiece 1. Therefore, the thickness information of the workpiece 1 may be expressed by the relationship between the distance from the center of the workpiece 1 and the thickness of the workpiece 1 at a position that is that distance away from the center of the workpiece 1. Further configuration examples of the thickness information of the workpiece 1 will be described in detail below.

[0075] Here, we will explain in detail the relationship between the deviation in thickness distribution of the workpiece 1 during grinding and the tilt of the table rotation axis 58. Below, we will explain an example in which the workpiece 1 is finish-ground by the second grinding unit 10b, but this relationship also applies when the workpiece is rough-ground by the first grinding unit 10a.

[0076] Fig. 3 is a plan view schematically showing the planar positional relationship between the holding surface 8a of the chuck table 8 and the annular orbit 20c on which the second grinding wheel 20b moves. In Fig. 3, the outline of the conical holding surface 8a of the chuck table 8 and the annular orbit 20c are shown in a circular form. The diameter of the circular annular orbit 20c is equal to the diameter of the holding surface 8a of the chuck table 8. The table rotation axis 58 of the chuck table 8 passes through the center 68 of the holding surface 8a.

[0077] 3 also shows the positions of the fixed shaft 60 that supports the chuck table 8 from below, and the two adjustment shafts 62 and 64. The fixed shaft 60 is located below approximately the center of the second grinding wheel 18b, and the fixed shaft 60 and the two adjustment shafts 62 and 64 are arranged to form the vertices of an equilateral triangle. The chuck table 8 is supported by the fixed shaft 60 and the adjustment shafts 62 and 64, and the adjustment shafts 62 and 64 function as an inclination adjustment unit.

[0078] For example, when the adjustment shaft 64 is extended or retracted without extending or retracting the adjustment shaft 62, the inclination of the chuck table 8 changes so that it rotates around a first axis 74 connecting the fixed shaft 60 and the adjustment shaft 62. On the other hand, when the adjustment shaft 62 is extended or retracted without extending or retracting the adjustment shaft 64, the inclination of the chuck table 8 changes so that it rotates around a second axis 76 connecting the fixed shaft 60 and the adjustment shaft 64. In other words, when the adjustment shaft 62 and the adjustment shaft 64 are extended or retracted, the inclination of the table rotation axis 58 can be changed.

[0079] When grinding the workpiece 1, the tilt of the table rotation axis 58 is adjusted by the tilt adjustment unit so that the generatrix connecting the center 68 and outer periphery 66 of the holding surface 8a, which overlaps with the annular orbit 20c, is parallel to the annular orbit 20c.

[0080] Then, the second grinding wheel 20b moving along the annular track 20c comes into contact with the back surface 1b of the workpiece 1 in a grinding region 72 between above the center 68 of the holding surface 8a and above the outer periphery 66, thereby grinding the workpiece 1. Note that the second grinding wheel 20b does not come into contact with the workpiece 1 in the region between above the center 68 of the holding surface 8a and above another outer periphery 70.

[0081] 4(A) and 4(B) are graphs illustrating the thickness distribution that appears in the workpiece 1 when grinding is performed on the workpiece 1 when the relative inclination of the table rotation axis 58 and the second spindle 14b is inappropriate. In each graph, the horizontal axis represents the distance from the center of the workpiece 1, and the vertical axis represents the magnitude of the thickness deviation of the workpiece 1.

[0082] When grinding the workpiece 1, the chuck table 8 is rotated around the table rotation axis 58, and the second grinding wheel 18b is rotated around the second spindle 14b. At this time, a circular region at a given distance from the center of the workpiece 1 is ground in the same manner, so the thickness distribution of the workpiece 1 is approximately constant in this circular region. Therefore, as shown in the graphs of Figures 4(A) and 4(B), the thickness distribution of the workpiece 1 can be evaluated from the relationship between the distance from the center of the workpiece 1 and the amount of thickness deviation of the workpiece 1.

[0083] The thickness distribution shown in the graph of Fig. 4(B) is an example of a thickness distribution that appears in the workpiece 1 when there is a gradient across the entire grinding region 72 between the center and outer periphery of the workpiece 1. This thickness distribution appears in the workpiece 1 when the annular orbit 20c of the second grinding wheel 20b is not parallel to the generatrix connecting the center 68 and outer periphery 66 of the holding surface 8a.

[0084] More specifically, the thickness distribution shown in the graph of Fig. 4(B) is the thickness distribution when the distance between the holding surface 8a and the annular orbit 20c is greater at the center 68 of the holding surface 8a than at the outer periphery 66. The difference between the thickness at the center of the workpiece 1 and the thickness at the outer periphery of the workpiece 1 is shown in Fig. 4(B) as thickness deviation V. Note that when the distance between the holding surface 8a and the annular orbit 20c is greater at the outer periphery 66 of the holding surface 8a than at the center 68 of the holding surface 8a, deviation V takes a negative value.

[0085] Note that this deviation V can also be called the "protrusion amount" or "V amount" due to the cross-sectional shape that appears on the workpiece 1 due to this deviation V. In order to eliminate the deviation in thickness distribution shown in the graph of FIG. 4(B), it is sufficient to adjust mainly the length of the adjustment shaft 64 so that the holding surface 8a and the annular orbit 20c become parallel.

[0086] As shown in Figure 4(B), this thickness deviation can be expressed by a linear function of the distance from the center of the workpiece 1 (horizontal axis) and the amount of deviation in the thickness of the workpiece 1 (vertical axis). When the horizontal axis of this linear function is zero, the vertical axis becomes V, and when the horizontal axis becomes R, which is the radius of the workpiece 1, the vertical axis becomes zero.

[0087] 4(A) is an example of the thickness distribution that appears on the workpiece 1 when the grinding depth of the second grinding wheel 20b becomes shallow or deep in the central part of the grinding region 72 between the center and the outer periphery of the workpiece 1. In order to eliminate the bias in the thickness distribution shown in FIG. 4(A), it is advisable to adjust the adjusting shaft 64 mainly while adjusting the adjusting shaft 62 so as to correspond to the change in the inclination across the entire grinding region 72 that changes due to the adjustment of the adjusting shaft 62.

[0088] More specifically, the thickness distribution shown in the graph of Fig. 4(A) is the thickness distribution when the grinding depth of the second grinding wheel 20b is shallow in the center of the grinding region 72 between the center and the periphery of the workpiece 1. The difference between the thickness in the center of the grinding region 72 of the workpiece 1 and the thickness at the center and the periphery is shown in Fig. 4(A) as the thickness deviation W. When the center of the grinding region 72 of the workpiece 1 is ground deeper than the periphery, W becomes a negative value.

[0089] Note that this deviation W can also be called the "seagull amount" or "W amount" due to the cross-sectional shape that appears on the workpiece 1 due to this deviation W. The adjustment amounts of the adjustment shafts 62, 64 are preferably determined so that this deviation W becomes zero.

[0090] As shown in Figure 4(A), this thickness deviation W can be expressed by a quadratic function of the distance from the center of the workpiece 1 (horizontal axis) and the amount of thickness deviation (vertical axis) of the workpiece 1. In this quadratic function, the vertical axis is zero when the horizontal axis is zero, the vertical axis is W when the horizontal axis is 0.5R, and the vertical axis is zero when the horizontal axis is R.

[0091] The thickness information of the workpiece 1 obtained using the thickness measuring devices 40, 42 may be composed of the V amount and the W amount. When the lengths of the adjustment axes 62, 64 are both appropriate, that is, when the relative inclination between the table rotation axis 58 and the spindles 14a, 14b is appropriate, the thickness of the workpiece 1 will be uniform throughout, and the V amount and the W amount will be zero.

[0092] Furthermore, when the relative inclination between the table rotation axis 58 and the spindles 14a, 14b is inappropriate, a thickness distribution that is the sum of the thickness distribution represented by the graph shown in Fig. 4(A) and the thickness distribution represented by the graph shown in Fig. 4(B) appears on the workpiece 1. Conversely, when the relative inclination between the table rotation axis 58 and the spindles 14a, 14b is inappropriate, the thickness distribution that appears on the workpiece 1 can be separated into the thickness distribution represented by the graph shown in Fig. 4(A) and the thickness distribution represented by the graph shown in Fig. 4(B).

[0093] The controller 90 calculates the adjustment amount so that the deviation W in the graph shown in Fig. 4(A) becomes zero and the deviation V in the graph shown in Fig. 4(B) becomes zero. Then, the relative tilt between the table rotation axis 58 and the spindles 14a, 14b is adjusted by the tilt adjustment unit.

[0094] In other words, the controller 90 includes a required adjustment amount calculation unit 94. The required adjustment amount calculation unit 94 acquires thickness information (e.g., thickness distribution at various locations on the workpiece 1 and the cross-sectional shape of the workpiece 1) of the workpiece 1 being ground by the grinding units 10a and 10b using the thickness measuring devices 40 and 42. Then, based on the thickness information, the required adjustment amount is calculated as the required adjustment amount for the tilt adjustment to be performed by the tilt adjustment unit. The controller 90 performs grinding of the workpiece 1 using the grinding control unit 92 while adjusting the relative tilt between the table rotation axis 58 and the spindles 14a and 14b using the calculated required adjustment amount.

[0095] However, it takes a certain amount of time from when adjustments such as the tilt of the table rotation axis 58 are made until the effects of the adjustments are reflected in the thickness distribution of the workpiece 1. In other words, at the point when adjustments such as the tilt of the table rotation axis 58 are completed, the thickness distribution of the workpiece 1 is not significantly corrected. After that, grinding of the workpiece 1 progresses to a certain extent, and grinding progresses more in the parts of the workpiece 1 that are thicker than expected than in the surrounding areas, thereby optimizing the thickness distribution of the workpiece 1.

[0096] That is, it takes a certain amount of time to optimize the thickness distribution of the workpiece 1. Therefore, control methods for feedback control of general actuators, etc., cannot be simply applied to grinding progress management in the grinding device 2. This can be explained by the fact that the relationship between the object to be corrected and the object of progress management is different between grinding progress management and feedback control of the drive source.

[0097] In grinding, the inclination of the table rotation axis 58, which is the object of operation correction, has no direct relationship to the thickness distribution of the workpiece 1, which is the object of progress management. In other words, the inclination adjustment unit in the grinding device 2 adjusts the inclination of the table rotation axis 58, etc., but does not adjust the shape of the workpiece 1.

[0098] In contrast, with a typical actuator, the motion of the movable part changes immediately when the operation mode of the drive source such as a motor is changed. In other words, the operation of the drive source, which is the object of operation correction in feedback control, directly affects the motion mode of the movable part, which is the object of progress management. Therefore, the control method of the actuator, etc. cannot be simply applied to the progress management of grinding in the grinding device 2.

[0099] For example, it is conceivable to operate the tilt adjustment unit to adjust the tilt of the table rotation axis 58 while grinding the workpiece 1, and then readjust the tilt of the table rotation axis 58 during the transitional period when the effect of the adjustment is reflected in the thickness distribution of the workpiece 1. In this case, the tilt of the table rotation axis 58, which has already been adjusted, is further changed, and the adjustment amount is likely to be excessive. As a result, it is difficult to achieve the thickness distribution of the workpiece 1 as expected.

[0100] Moreover, excessive adjustment and excessive correction of the excessive adjustment are repeated, resulting in repeated rapid and slow decreases in the thickness of the workpiece 1 during grinding. When the processing conditions and processing process become unstable in this way, it is difficult to obtain stable processing results.

[0101] On the other hand, if the next adjustment is to be made on an ongoing basis until the effect of the adjustment is reflected in the thickness distribution of the workpiece 1, the number of adjustments that can be made during grinding of the workpiece 1 will decrease. As a result, adjustments that correspond to the constantly changing machining conditions will not be possible, and the machining results will vary more.

[0102] Incidentally, a method called PID control (Proportional-Integral-Differential Controller, PID Controller) is known as a feedback control method for actuators, etc. This is a method of adjusting the input value in response to the deviation between the output value and the target value using three elements: a proportional term, an integral term, and a derivative term.

[0103] Of these, the basic feedback control that uses only a term proportional to the deviation is called P control. In P control, the input value is adjusted by increasing the adjustment amount when the deviation is large and decreasing the adjustment amount when the deviation is small. Feedback control that uses a term proportional to the deviation and an integral term is called PI control. The integral term serves the purpose of increasing the change in the input value to bring it closer to the target value if a state of deviation continues for a long time. However, this has the effect of delaying control, which can easily make the output value unstable.

[0104] The term proportional to the derivative of the deviation serves to suppress oscillatory behavior of the output value and smoothly guide the output value to the target value. This type of control, which combines proportional action, integral action, and derivative action, is called PID control.

[0105] It is conceivable to apply the above-mentioned PID control or P control as a control method for actuators, etc., to manage the progress of grinding in the grinding device 2. For example, the necessary adjustment amount calculation unit 94 of the controller 90 calculates the necessary adjustment amount so as to PID control the tilt based on the thickness information of the workpiece 1 acquired by the thickness measuring devices 40 and 42. Alternatively, the necessary adjustment amount calculation unit 94 of the controller 90 calculates the necessary adjustment amount so as to P control the tilt based on the thickness information of the workpiece 1 acquired by the thickness measuring devices 40 and 42.

[0106] However, simple PID control or P control is not capable of responding to changes in shape due to changes in the processing conditions in the grinding device 2 (changes in the inclination of the processing point due to changes in the processing load, effects of thermal expansion of the component, etc.) As will be described in detail later, it has been confirmed that simply applying these control methods to the management of the progress of grinding in the grinding device 2 results in variations in the finished shape of the workpiece 1.

[0107] So far, it has been explained that when the controller 90 of the grinding apparatus 2 adjusts the relative tilt between the table rotation axis 58 and the spindles 14a, 14b with or without using a control method such as an actuator, the adjustment cannot be simply performed using the calculated required adjustment amount. Therefore, in the grinding apparatus 2 according to this embodiment, the controller 90 multiplies the required adjustment amount calculated by the required adjustment amount calculation unit 94 by a predetermined adjustment rate to calculate an actual adjustment amount, and adjusts the tilt using the actual adjustment amount.

[0108] In other words, the controller 90 of the grinding machine 2 according to this embodiment further includes an actual adjustment amount calculation unit 96 that calculates an actual adjustment amount by multiplying the required adjustment amount calculated by the required adjustment amount calculation unit 94 by an adjustment rate, and an adjustment control unit 98 that adjusts the tilt using the actual adjustment amount. The adjustment control unit 98 controls the tilt adjustment unit to appropriately adjust the tilt using the actual adjustment amount calculated by the actual adjustment amount calculation unit 96. This adjustment is performed taking into account circumstances specific to grinding of the workpiece 1 in the grinding machine 2.

[0109] Here, the relationship between the adjustment rate by which the adjustment control unit 98 multiplies the required adjustment amount when calculating the actual adjustment amount and the change in thickness of the workpiece 1 being ground by the grinding units 10a and 10b will be described. In particular, the description will be based on an experiment in which the V amount described in Fig. 4(B) was acquired as thickness information of the workpiece 1, the required adjustment amount was calculated from the V amount, and the required adjustment amount was multiplied by various adjustment rates to calculate the actual adjustment amount, and the tilt of the spindles 14a and 14b was adjusted.

[0110] An experiment in which the workpiece 1 was ground while adjusting the inclination of the spindles 14a and 14b was carried out as follows. First, a plurality of Si wafers with a diameter of 12 inches were prepared as the workpieces 1, and grinding wheels 18a and 18b suitable for grinding Si wafers were attached to the lower ends of the spindles 14a and 14b. Next, one workpiece 1 was placed on the holding surface 8a of the chuck table 8, and the workpiece 1 was held by suction on the chuck table 8. After that, the chuck table 8 was moved to a predetermined position below the grinding wheels 18a and 18b.

[0111] Then, rotation of spindles 14a, 14b was started to raise the rotational speed to 3400 rpm, rotation of chuck table 8 was started to raise the rotational speed to 300 rpm, and grinding wheels 18a, 18b began to lower. While grinding wheels 20a, 20b came into contact with the upper surface (rear surface 1b) of workpiece 1 to grind and thin it, the thickness of workpiece 1 was monitored by thickness measuring devices 40, 42, and the V amount was acquired as thickness information of workpiece 1.

[0112] At this time, while referring to the acquired V amount, the necessary adjustment amount for adjusting the tilt of the spindles 14a, 14b was repeatedly calculated so that P control would be performed on the V amount so that the V amount would ultimately become zero. Then, each time the necessary adjustment amount was calculated, it was multiplied by a predetermined adjustment rate to calculate an actual adjustment amount, and the tilt of the spindles 14a, 14b was adjusted using the actual adjustment amount. In this way, the transition of the V amount was observed while grinding of the workpiece 1 progressed.

[0113] Here, different adjustment rates were used to calculate the actual adjustment amounts in the experiments performed on each of the multiple workpieces 1. More specifically, when the adjustment amount required to perform adjustment by P control is Δy(t), the adjustment rate Kp by which Δy(t) is multiplied is set to 0, 0.2, 0.3, 0.4, 0.5, or 1.0, and the actual adjustment amounts are calculated based on the respective adjustment rates, and the inclinations of the spindles 14a and 14b are adjusted based on the actual adjustment amounts.

[0114] The results of the experiment will be explained. Fig. 5(A) is a graph showing the change in the amount of V when the adjustment rate Kp is 0.0, Fig. 5(B) is a graph showing the change in the amount of V when the adjustment rate Kp is 0.2, Fig. 6(A) is a graph showing the change in the amount of V when the adjustment rate Kp is 0.3, Fig. 6(B) is a graph showing the change in the amount of V when the adjustment rate Kp is 0.4, Fig. 7(A) is a graph showing the change in the amount of V when the adjustment rate Kp is 0.5, and Fig. 7(B) is a graph showing the change in the amount of V when the adjustment rate Kp is 1.0.

[0115] In each graph, grinding wheels 20a, 20b come into contact with workpiece 1 around the time elapsed reaching 20 s (20 seconds), grinding of workpiece 1 begins, thickness information of workpiece 1 is acquired, and adjustment of the inclination of spindles 14a, 14b, etc. begins. Then, around the time elapsed reaching 100 s (100 seconds), the descent of grinding wheels 18a, 18b is stopped, and grinding of workpiece 1 is completed.

[0116] Each graph will be evaluated individually below. First, when the adjustment rate Kp was set to 0.0, i.e., when the actual adjustment amount was zero and essentially no adjustment was performed, the V amount remained at a constant deviation from zero, as shown in Figure 5(A). From this result, it can be seen that if the inclination of the spindles 14a, 14b, etc. is not adjusted, the workpiece 1 of the desired shape cannot be obtained.

[0117] Next, when the adjustment rate Kp is set to 1.0, that is, when the required adjustment amount is simply used as the actual adjustment amount and adjustment is performed by P control, it was confirmed that the V amount oscillates around zero, as shown in Figure 7(B). The oscillation of the V amount means that the adjustment of the inclination of the spindles 14a and 14b and the correction of the adjustment are repeated.

[0118] In the experimental results shown in Figure 7(B), when the amount of V approached zero, the grinding wheels 18a, 18b stopped descending and grinding of the workpiece 1 was completed, but this can be considered to be a coincidence. Depending on the progress of grinding, it is possible that grinding will end when the amount of V is significantly different from zero.

[0119] That is, from this result, it can be seen that when the tilt of the spindles 14a, 14b is adjusted simply by P control, vibrations are observed in the V amount, and it is difficult for the V amount to remain constant at the time when grinding is completed. In other words, it can be seen that stable grinding results cannot be obtained by simple P control. It is thought that the same applies when PID control is performed instead of P control.

[0120] In this regard, even when the adjustment rate Kp was set to 0.5, similar oscillations were observed in the V amount, as shown in Figure 7(A). However, compared to when Kp was set to 1.0, the oscillation period was longer when Kp was 0.5. This shows that the oscillation pattern of the V amount changes depending on Kp.

[0121] When the adjustment rate Kp was set to 0.4, as shown in Figure 6(B), the V amount was hardly observed to fluctuate, and it was confirmed that the V amount converged to a value close to zero. Similarly, when the adjustment rate Kp was set to 0.3, as shown in Figure 6(A), it was confirmed that the V amount converged to a value close to zero. As shown in Figure 5(B), a similar tendency was confirmed when the adjustment rate Kp was set to 0.2.

[0122] Therefore, in the environment in which this experiment was conducted, it is understood that if the actual adjustment amount is calculated with the adjustment rate Kp set to 0.2 or more and 0.4 or less, and the inclination of the spindles 14a, 14b is adjusted using the calculated actual adjustment amount, good grinding results can be obtained.

[0123] However, when Kp was 0.4, as shown in Figure 6(B), a relatively large overshoot of the V amount was confirmed before the elapsed time was 60 seconds. On the other hand, when Kp was 0.2, as shown in Figure 5(B), it was confirmed that the time it took for the V amount to approach zero was relatively long, and that the V amount converged at a value lower than zero. Therefore, it is understood that an adjustment ratio Kp of 0.3 is most preferable.

[0124] The above experiments have confirmed that good grinding results can be obtained by acquiring thickness information of the workpiece 1, calculating the required adjustment amount based on the thickness information, and multiplying this required adjustment amount by a predetermined adjustment rate Kp to calculate the actual adjustment amount and adjusting the inclination of the spindles 14a, 14b, etc. It has also been found that when grinding the workpiece 1 under the same processing conditions as in the above experiments, good grinding results can be obtained by setting the adjustment rate Kp to 0.2 or more and 0.4 or less.

[0125] That is, by multiplying the required adjustment amount by a predetermined adjustment rate Kp to calculate the actual adjustment amount, and adjusting the tilt using the actual adjustment amount, the tilt is adjusted at an appropriate speed and adjustment and correction are not repeated. This reduces variations in the machining results that accompany tilt adjustment. Therefore, with the grinding device 2 according to this embodiment, by appropriately adjusting the machining conditions while grinding the workpiece 1, the workpiece 1 can be ground accurately and uniformly to a predetermined thickness.

[0126] When grinding is performed under new grinding conditions in the grinding device 2, it is advisable to carry out tests in advance in which the workpiece 1 is ground while changing the adjustment rate, and derive an adjustment rate that will give good and stable processing results. In this case, grinding is performed using the derived adjustment rate, so that good processing results can be obtained stably.

[0127] However, the adjustment ratio used when grinding the workpiece 1 does not need to be derived by an experimental method. When the conditions for grinding to be performed by the grinding apparatus 2 are input, the controller 90 of the grinding apparatus 2 may read out the adjustment ratio used when grinding was previously performed under similar conditions by the grinding apparatus 2. In this case, when grinding is performed using the read-out adjustment ratio, good processing results can be obtained.

[0128] The adjustment rate by which the required adjustment amount can be multiplied to calculate the actual adjustment amount does not need to be determined in advance. The actual adjustment amount calculation unit 96 may calculate the adjustment rate under predetermined conditions each time grinding of the workpiece 1 is performed, and calculate the actual adjustment amount using the calculated adjustment rate. In this case, for example, the actual adjustment amount calculation unit 96 may determine the adjustment rate based on thickness information of the workpiece 1 acquired by the thickness measuring devices 40, 42, or the required production amount calculated by the required adjustment amount calculation unit 94.

[0129] For example, if the shape of the workpiece 1 indicated by the thickness information deviates significantly from the ideal state and the required production volume calculated by the required adjustment amount calculation unit 94 is relatively large, the adjustment rate is increased to greatly adjust the relative inclination between the table rotation axis 58 and the spindles 14a, 14b. In this case, it is possible to avoid a situation where the adjustment is not completed in time before grinding is completed and sufficient adjustment is not performed.

[0130] On the other hand, for example, if the deviation from the ideal state of the shape of the workpiece 1 indicated by the thickness information is small and the required production amount calculated by the required adjustment amount calculation unit 94 is relatively small, the adjustment rate is reduced to finely adjust the relative tilt of the table rotation axis 58 and the spindles 14a, 14b. In this case, it is possible to avoid a situation in which adjustment and excessive correction of excessive adjustment are repeated, making it easier to obtain stable processing results.

[0131] Furthermore, the value of the adjustment rate used by the actual adjustment amount calculation unit 96 while grinding of the workpiece 1 is being performed does not have to be one. In other words, the adjustment rate used by the actual adjustment amount calculation unit 96 may change while grinding of one workpiece 1 progresses.

[0132] For example, the actual adjustment amount calculation unit 96 adjusts the tilt at a relatively high adjustment rate while the shape of the workpiece 1 indicated by the thickness information is significantly deviated from the ideal state, i.e., while the required adjustment amount is calculated to be high. On the other hand, when the shape of the workpiece 1 indicated by the thickness information is less deviated from the ideal state, i.e., when the required adjustment amount is calculated to be low, the actual adjustment amount calculation unit 96 adjusts the tilt at a relatively low adjustment rate. In this way, the actual adjustment amount calculation unit 96 may switch the adjustment rate.

[0133] Here, the value indicated by the thickness information of the workpiece 1, which is the condition for switching the adjustment rate, or the threshold value of the required adjustment amount, is referred to as the selection threshold. For example, the actual adjustment amount calculation unit 96 sets the adjustment rate to the first adjustment rate when the value indicated by the thickness information or the required adjustment amount calculated by the required adjustment amount calculation unit 94 is higher than the selection threshold. On the other hand, when the value indicated by the thickness information or the required adjustment amount is equal to or lower than the selection threshold, the actual adjustment amount calculation unit 96 sets the adjustment rate to the second adjustment rate, which is smaller than the first adjustment rate.

[0134] Next, we will explain an experiment in which the adjustment rate by which the actual adjustment amount calculation unit 96 multiplies the required adjustment amount when calculating the actual adjustment amount is changed while grinding of the workpiece 1 is in progress, and the adjustment control unit 98 adjusts the inclination of the spindles 14a, 14b, etc. based on the calculated actual adjustment amount.

[0135] In this experiment, as in the above-mentioned experiment, the V amount described in FIG. 4(B) was obtained as thickness information of the workpiece 1, and the adjustment rate was calculated from the V amount. Then, the inclination of the spindles 14a and 14b was adjusted so that the V amount approached zero. Note that in this experiment, the adjustment rate was calculated using a different method while grinding each of the three workpieces 1. Here, the grinding conditions for the workpieces 1 performed in this experiment were the same as those for the above-mentioned experiment, so a description of the grinding conditions for this experiment will be omitted.

[0136] In this experiment, when the adjustment amount required to perform adjustment by P control is Δy(t), the adjustment rate Kp by which this Δy(t) is multiplied was selected under the following conditions: First, the actual adjustment amount was calculated under the condition that the adjustment rate Kp was set to 0.5 when the absolute value of the V amount indicated by the thickness information exceeded 0.5 μm, and the adjustment rate Kp was set to 0.1 when the absolute value of the V amount was 0.5 μm or less, and the workpiece 1 was ground while adjusting the inclination of the spindles 14a and 14b. This is the first condition.

[0137] Furthermore, the actual adjustment amount was calculated under the condition that when the absolute value of the V amount, which is the value indicated by the thickness information, exceeds 0.5 μm, the adjustment rate Kp is set to 0.3, and when the absolute value of the V amount is 0.5 μm or less, the adjustment rate Kp is set to 0.1, and the workpiece 1 was ground while adjusting the inclination of the spindles 14a and 14b. This is defined as the second condition.

[0138] That is, under the first and second conditions, the absolute value of the V amount, which is the value indicated by the thickness information, is 0.5 μm, which is the selected threshold value. Furthermore, for comparison, the actual adjustment amount was calculated with the adjustment rate set to 0.1 regardless of the V amount, and the workpiece 1 was ground while adjusting the inclination of the spindles 14a and 14b. This is the comparison condition.

[0139] The results of the experiment will be explained below. Fig. 8 is a graph showing the change in the amount of V when the adjustment rate Kp is determined under the comparative conditions, Fig. 9(A) is a graph showing the change in the amount of V when the adjustment rate Kp is determined under the first conditions, and Fig. 9(B) is a graph showing the change in the amount of V when the adjustment rate Kp is determined under the second conditions.

[0140] In each graph, when the elapsed time was between 0 and 10 seconds (0 to 10 seconds), grinding wheels 20a and 20b came into contact with workpiece 1, grinding of workpiece 1 began, thickness information of workpiece 1 was acquired, and adjustment of the inclination of spindles 14a and 14b began. Then, when the elapsed time was between 90 and 100 seconds (90 to 100 seconds), the descent of grinding wheels 18a and 18b was stopped, and grinding of workpiece 1 was completed.

[0141] Each graph will be evaluated individually below. First, when the adjustment rate Kp was set to 0.1 from the start to the end of grinding, that is, when the tilt of the spindles 14a and 14b was adjusted under the comparative conditions, it was confirmed that the V amount gradually approached zero, as shown in Figure 8. However, the progress of the V amount adjustment was too slow.

[0142] Next, when the tilt of the spindles 14a and 14b was adjusted under the first condition, the amount of V changed as shown in Figure 9(A). First, the tilt of the spindles 14a and 14b was adjusted relatively quickly with an adjustment rate Kp of 0.5, and it was confirmed that the amount of V, which had been negative, rapidly approached zero between 20 and 40 seconds. However, the amount of V increased rapidly, and even after the absolute value of the amount of V became 0.5 μm or less and the adjustment rate Kp was switched to 0.1, the rapid increase in the amount of V did not stop, and it was confirmed that the amount of V overshot.

[0143] When the tilt of the spindles 14a and 14b was adjusted under the second condition, the amount of V changed as shown in Fig. 9(B). First, the tilt of the spindles 14a and 14b was adjusted with an adjustment rate Kp of 0.3, and it was confirmed that the amount of V, which had been negative, approached zero between 20 seconds and 50 seconds.

[0144] When the tilt of the spindles 14a and 14b was adjusted under the second condition, the increase in the V amount was more gradual than when adjusting under the first condition, and it took a relatively long time to correct the V amount. On the other hand, no overshoot of the V amount was observed after the absolute value of the V amount became 0.5 μm or less and the adjustment rate Kp was switched to 0.1.

[0145] Whether the tilt of the spindles 14a, 14b was adjusted under the first or second condition, the V amount could be brought significantly closer to zero in a relatively short time. On the other hand, after the V amount approached zero, adjustment could be carried out carefully. In this way, when grinding the workpiece 1 while adjusting the tilt of the spindles 14a, 14b, etc. by switching the adjustment rate Kp depending on the V amount, adjustment can be carried out quickly and precisely, and good machining results can be obtained stably.

[0146] Here, the selection threshold referenced when switching the adjustment rate Kp should be set so that the tilt of the spindles 14a, 14b, etc. can be adjusted quickly and precisely. In other words, if the selection threshold is too small, the tilt adjustment is performed at a large adjustment rate Kp even if the V amount is significantly reduced, which makes it easier for overshoot to occur in indicators related to the thickness of the workpiece 1, such as the V amount. On the other hand, if the selection threshold is too large, the tilt adjustment starts at a small adjustment rate Kp when the V amount is large, and it takes a long time to adjust the tilt.

[0147] Also, up to this point, we have explained a case where adjustment is performed by switching the adjustment rate Kp depending on whether the V amount exceeds the selection threshold or is equal to or less than the selection threshold. That is, we have explained a case where two stages of adjustment are performed with the selection threshold as the boundary. However, two or more selection thresholds may be used, and three or more stages of adjustment may be performed.

[0148] Next, as a method of using the grinding device 2 according to this embodiment, a method of grinding the workpiece 1 performed by the grinding device 2 will be described. The method of grinding the workpiece 1 described below is performed, for example, by the grinding device 2 shown in Fig. 1. Fig. 10 is a flowchart showing the flow of each step of the method of grinding the workpiece 1.

[0149] In the grinding method for workpiece 1 shown in FIG. 10, first, workpiece 1 is placed on holding surface 8a of chuck table 8, and holding step S10 is performed in which workpiece 1 is held by chuck table 8.

[0150] In the holding step S10, the back surface 1b of the workpiece 1, which will be the surface to be ground, is faced upward, and the front surface 1a is faced toward the holding surface 8a, and the workpiece 1 is placed on the holding surface 8a. Next, the suction source of the chuck table 8 is activated, and the workpiece 1 is held by suction on the chuck table 8. Thereafter, the chuck table 8, which holds the workpiece 1 by suction, is moved below the grinding units 10a and 10b, completing preparations for grinding the workpiece 1.

[0151] In the grinding method for the workpiece 1 shown in Fig. 10, a grinding step S20 is performed after a holding step S10. Fig. 2 is a cross-sectional view schematically showing how the workpiece 1 is ground by the second grinding unit 10b.

[0152] In the grinding step S20, the chuck table 8 is rotated around the table rotation axis 58, and the spindles 14a, 14b are also rotated, causing the chuck table 8 and the spindles 14a, 14b to move relatively toward each other. This brings the grinding wheels 20a, 20b into contact with the workpiece 1, thereby grinding the workpiece 1.

[0153] Here, in the grinding step S20, thickness information of the workpiece 1 being ground is obtained using the thickness measuring devices 40, 42. Then, based on the obtained thickness information, the adjustment amount required to adjust the tilt of one or both of the table rotation axis 58 and the spindles 14a, 14b is calculated as the required adjustment amount. In particular, in the grinding method for the workpiece 1 shown in Fig. 10, the required adjustment amount is multiplied by the adjustment rate to calculate the actual adjustment amount, and the tilt is adjusted using this actual adjustment amount.

[0154] In the grinding step S20, the required adjustment amount may be calculated so that the tilt of the adjustment target can be PID controlled based on the thickness information acquired for the workpiece 1. Alternatively, in the grinding step S20, the required adjustment amount may be calculated so that the tilt can be P-controlled based on the thickness information. However, the method of calculating the required adjustment amount is not limited to these.

[0155] In addition, in the grinding step S20, the adjustment rate by which the required adjustment amount is multiplied is preferably determined based on the thickness information or the required adjustment amount. For example, in the grinding step S20, when the value indicating the thickness information or the required adjustment amount is higher than a selection threshold, the adjustment rate may be set to a first adjustment rate, and when the value is equal to or lower than the selection threshold, the adjustment rate may be set to a second adjustment rate smaller than the first adjustment rate.

[0156] As described above, the grinding apparatus 2 according to this embodiment adjusts the inclination of one or both of the table rotation axis 58 and the spindles 14a and 14b while grinding the workpiece 1 with the grinding wheels 18a and 18b. More specifically, thickness information of the workpiece 1 being ground is acquired, and the adjustment amount required to adjust this inclination is calculated as the required adjustment amount based on the thickness information. The required adjustment amount is then multiplied by the adjustment rate to calculate the actual adjustment amount. The inclination is then adjusted using the actual adjustment amount.

[0157] In this case, by selecting an appropriate adjustment rate so that the tilt can be adjusted at an appropriate speed and so that adjustment and correction of the adjustment do not occur repeatedly, variations in the processing results associated with tilt adjustment can be reduced.

[0158] The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, in the above-described embodiment, attention is focused on the V amount as thickness information of the workpiece 1, and the necessary adjustment amount is calculated so that the V amount becomes zero during grinding of the workpiece 1, and the inclination of the table rotation axis 58, etc. is adjusted to achieve the situation where the V amount becomes zero. However, one aspect of the present invention is not limited to this.

[0159] That is, in the grinding apparatus 2 and grinding method according to one embodiment of the present invention, the W amount described in Fig. 4(A) may be used instead of the V amount as thickness information of the workpiece 1 that serves as an index for adjustment. In this case, the required adjustment amount may be calculated with the aim of making the W amount zero during grinding of the workpiece 1. Furthermore, the required adjustment amount may be calculated with reference to information about the thickness of the workpiece 1 that is separate from the V amount and W amount.

[0160] Furthermore, in the above embodiment, experimental results were shown, and a case where the adjustment rate by which the required adjustment amount is multiplied was mainly described, while referring to the V amount as thickness information of the workpiece 1. However, one aspect of the present invention is not limited to this. That is, in the grinding apparatus 2 and grinding method according to one aspect of the present invention, the adjustment rate by which the required adjustment amount is multiplied may be determined while referring to the W amount instead of the V amount as thickness information of the workpiece 1. Alternatively, the adjustment rate may be determined while referring to an index other than the V amount or the W amount as thickness information of the workpiece 1.

[0161] Furthermore, the actual adjustment amount calculation unit 96 of the grinding machine 2 according to one aspect of the present invention may determine the adjustment rate based on the required adjustment amount calculated by the required adjustment amount calculation unit 94 instead of the thickness information of the workpiece 1. The actual adjustment amount calculation unit 96 may set the adjustment rate to a first adjustment rate when a value indicating the required adjustment amount instead of the thickness information is higher than a selection threshold, and may set the adjustment rate to a second adjustment rate smaller than the first adjustment rate when this value is equal to or smaller than the selection threshold. In other words, the selection threshold may be set for the required adjustment amount instead of the thickness information.

[0162] The thickness information of the workpiece 1 during grinding indicates the deviation of the shape of the workpiece 1 from the ideal state when grinding proceeds ideally. Furthermore, the required adjustment amount for the tilt of the table rotation axis 58, etc. is the adjustment amount required to bring the shape of the workpiece 1 into the ideal state, and is influenced by the deviation of the shape of the workpiece 1 from the ideal state.

[0163] That is, whether the adjustment rate is determined based on the thickness information of the workpiece 1 or the required adjustment amount, the adjustment amount is determined based on the deviation of the shape of the workpiece 1 from the ideal state. Therefore, even when the adjustment rate is determined based on the required adjustment amount calculated by the required adjustment amount calculation unit 94, the inclination of the table rotation axis 58, etc. can be appropriately adjusted, just like when the adjustment rate is determined based on the thickness information of the workpiece 1.

[0164] As described above, the workpiece 1 can be ground using the grinding device 2 and grinding method according to one aspect of the present invention. From another perspective, when the grinding method according to one aspect of the present invention is carried out, the ground workpiece 1 is obtained. In other words, the ground workpiece 1 is manufactured. In particular, a high-quality workpiece 1 is manufactured that is not affected by variations in the processing results that occur when adjusting the inclination of the table rotation axis 58 and / or the spindles 14a, 14b.

[0165] The ground workpiece 1 is then divided and used to manufacture chips. High-quality chips can be obtained by dividing the high-quality workpiece 1 that has been ground using the grinding device 2 and grinding method.

[0166] The procedure of the manufacturing method for manufacturing the ground workpiece 1 by grinding the workpiece 1 with the grinding device 2 is no different from the procedure of the grinding method according to the above-mentioned embodiment of the present invention. Therefore, the explanation of the manufacturing method for manufacturing the ground workpiece 1 is substantially complete. Below, the procedure of the manufacturing method for manufacturing the ground workpiece 1 will be explained for confirmation, but the explanation of the above-mentioned method for grinding the workpiece 1 should be taken into consideration as appropriate. Figure 11 is a flowchart showing the flow of each step of the manufacturing method for manufacturing the ground workpiece 1.

[0167] In the manufacturing method of the ground workpiece 1 shown in Figure 11, first, the workpiece 1 is placed on the holding surface 8a of the chuck table 8 and the workpiece 1 is held by the chuck table 8 (S10, holding step).

[0168] Next, the chuck table 8 is rotated around the table rotation axis 58, and the spindles 14a, 14b are rotated, and the chuck table 8 and the spindles 14a, 14b are moved relatively in a direction approaching each other, and the grinding wheels 20a, 20b are brought into contact with the workpiece 1 to grind the workpiece 1, thereby producing a ground workpiece 1 (S20, grinding step).

[0169] Here, when grinding wheels 20a, 20b are brought into contact with workpiece 1 to grind the workpiece 1, thickness information of the workpiece 1 being ground is obtained. Then, based on the obtained thickness information, the adjustment amount required to adjust the tilt of one or both of table rotation axis 58 and spindles 14a, 14b is calculated as the required adjustment amount. In particular, in the manufacturing method of a ground workpiece shown in Figure 11, the required adjustment amount is multiplied by the adjustment rate to calculate the actual adjustment amount, and the tilt is adjusted using this actual adjustment amount.

[0170] When grinding the workpiece 1, the required adjustment amount may be calculated so that the tilt of the adjustment target can be PID controlled based on the thickness information acquired for the workpiece 1. Alternatively, the required adjustment amount may be calculated so that the tilt can be P-controlled based on the thickness information. However, the method for calculating the required adjustment amount is not limited to these.

[0171] Furthermore, it is preferable that the adjustment rate by which the required adjustment amount is multiplied is determined based on the thickness information or the required adjustment amount when grinding the workpiece 1. For example, when the value indicating the thickness information or the required adjustment amount is higher than a selected threshold, the adjustment rate may be set to a first adjustment rate, and when the value is equal to or lower than the selected threshold, the adjustment rate may be set to a second adjustment rate smaller than the first adjustment rate.

[0172] By selecting an appropriate adjustment rate so that the tilt can be adjusted at an appropriate speed during grinding and so that repeated adjustment and correction of the adjustment does not occur, it is possible to reduce variations in the machining results that accompany tilt adjustment, and therefore a high-quality ground workpiece 1 can be obtained.

[0173] The ground workpiece 1 is carried out of the grinding machine 2 and divided into chips. The steps of the chip manufacturing method will be described below, but the above-mentioned explanations of the grinding method for the workpiece 1 and the manufacturing method for the ground workpiece 1 should be referred to as appropriate. Figure 12 is a flowchart showing the flow of each step in the chip manufacturing method.

[0174] In the method for manufacturing a chip shown in FIG. 12, first, the workpiece 1 is placed on the holding surface 8a of the chuck table 8, and the workpiece 1 is held by the chuck table 8 (S10, holding step).

[0175] Next, the chuck table 8 is rotated around the table rotation axis 58, and the spindles 14a, 14b are rotated, and the chuck table 8 and the spindles 14a, 14b are moved relatively in a direction approaching each other, and the grinding wheels 20a, 20b are brought into contact with the workpiece 1 to grind the workpiece 1, thereby producing a ground workpiece 1 (S20, grinding step).

[0176] Here, when grinding wheels 20a, 20b are brought into contact with workpiece 1 to grind workpiece 1, thickness information of the workpiece 1 being ground is obtained. Then, based on the obtained thickness information, the adjustment amount required to adjust the tilt of one or both of table rotation axis 58 and spindles 14a, 14b is calculated as the required adjustment amount. In particular, in the tip manufacturing method shown in Figure 12, the required adjustment amount is multiplied by the adjustment rate to calculate the actual adjustment amount, and the tilt is adjusted using this actual adjustment amount.

[0177] When grinding the workpiece 1, the required adjustment amount may be calculated so that the tilt of the adjustment target can be PID controlled based on the thickness information acquired for the workpiece 1. Alternatively, the required adjustment amount may be calculated so that the tilt can be P-controlled based on the thickness information. However, the method for calculating the required adjustment amount is not limited to these.

[0178] Furthermore, it is preferable that the adjustment rate by which the required adjustment amount is multiplied is determined based on the thickness information or the required adjustment amount when grinding the workpiece 1. For example, when the value indicating the thickness information or the required adjustment amount is higher than a selected threshold, the adjustment rate may be set to a first adjustment rate, and when the value is equal to or lower than the selected threshold, the adjustment rate may be set to a second adjustment rate smaller than the first adjustment rate.

[0179] After grinding of the workpiece 1 in the grinding device 2 is completed, the ground workpiece 1 is removed from the grinding device 2 and transported to a processing device that divides the workpiece 1. Before the workpiece 1 is transported into the processing device, the workpiece 1 is integrated with a sheet (adhesive tape) called dicing tape and an annular frame made of a material such as metal. In other words, a work unit is formed in which the workpiece 1, the sheet, and the annular frame are integrated.

[0180] For example, a work unit is formed by fixing a sheet to the back surface 1b side of the workpiece 1. Fig. 13 is a perspective view showing a schematic view of a work unit 11 formed by integrating the workpiece 1, the annular frame 7, and the sheet 9.

[0181] The annular frame 7 is made of a metal material such as aluminum or stainless steel. An opening is provided in the center of the annular frame 7. The opening penetrates the annular frame 7 from the front to the back, and has a diameter larger than the diameter of the workpiece 1.

[0182] The sheet 9 is fixed to the annular frame 7 so as to cover the opening of the annular frame 7. The sheet 9 has a diameter larger than the diameter of the opening of the annular frame 7. The sheet 9 is, for example, an adhesive tape including a base layer formed of a resin film or the like and an adhesive layer formed on one side of the base layer. For example, the adhesive layer is preferably made of an ultraviolet-curable resin or a thermosetting resin. In this case, the fixing force of the sheet 9, which is caused by the adhesive force of the adhesive layer, can be reduced by irradiating the sheet 9 with ultraviolet light or by heating the sheet 9.

[0183] When the sheet 9 is attached to the annular frame 7 so as to close the opening, the adhesive layer of the sheet 9 is exposed in the opening. Then, the workpiece 1 is attached to the sheet 9 from the back surface 1b side in the opening.

[0184] The sheet 9 does not necessarily have to include an adhesive layer. A sheet 9 that does not include an adhesive layer is fixed to the back surface 1b of the workpiece 1 by, for example, thermocompression bonding, rather than being fixed to the back surface 1b by the adhesive force of an adhesive layer. Therefore, a sheet that does not include an adhesive layer and is fixed to the workpiece 1 by thermocompression bonding can also be called a thermocompression sheet.

[0185] After the work units 11 are formed, the protective member 3 attached to the surface 1a of the workpiece 1 is peeled off. Fig. 13 schematically shows the workpiece 1 with the protective member 3 peeled off and the surface 1a side exposed upward. As shown in Fig. 13, for example, a plurality of mutually intersecting planned division lines 13 are set on the surface 1a of the workpiece 1, and devices 5 are formed in each area partitioned by the planned division lines 13.

[0186] The workpiece 1 on which multiple devices 5 are formed is ground from the back surface 1b side to thin it, and then the workpiece 1 is divided along the planned division lines 13 to produce multiple thin device chips (chips), each of which has a device 5. The division of the workpiece 1 is performed, for example, by a cutting device equipped with an annular cutting blade. A work unit 11 including the workpiece 1 is transported to the cutting device.

[0187] 13 is a perspective view that schematically illustrates how a workpiece 1 is cut by a cutting device 102 to produce chips. The cutting device 102 includes a cutting unit 104 that cuts the workpiece 1 and a chuck table (not shown) that holds the workpiece 1. The cutting unit 104 includes a cutting blade 108 that has an annular grinding wheel portion, and a spindle (not shown) that has its tip inserted into a central through-hole of the cutting blade 108 and rotates the cutting blade 108. The cutting blade 108 includes, for example, an annular base that has a through-hole in the center, and an annular grinding wheel portion disposed on the outer periphery of the annular base.

[0188] The base end of the spindle is connected to a spindle motor (not shown) housed inside the spindle housing 106, and when the spindle motor is operated, the cutting blade 108 can be rotated.

[0189] When the workpiece 1 is cut by the cutting blade 108, heat is generated due to friction between the cutting blade 108 and the workpiece 1. Furthermore, when the workpiece 1 is cut, cutting chips are generated from the workpiece 1. Therefore, in order to remove the heat and cutting chips generated by cutting, cutting water such as pure water is supplied to the cutting blade 108 and the workpiece 1 while the workpiece 1 is being cut. The cutting unit 104 is provided, for example, with a cutting water supply nozzle 110 on the side of the cutting blade 108, which supplies cutting water to the cutting blade 108, etc.

[0190] 12, after the ground workpiece 1 is carried out from the grinding device 2, the workpiece 1 is divided to produce individual chips (S30, dividing step). For example, the workpiece 1 is divided by being cut by a cutting device 102.

[0191] When cutting the workpiece 1, the work unit 11 is placed on a chuck table (not shown), and the workpiece 1 is held on the chuck table via a sheet 9. The chuck table is then rotated to align the planned dividing line 13 of the workpiece 1 with the processing feed direction of the cutting device 102. The relative positions of the chuck table and the cutting unit 104 are also adjusted so that the cutting blade 108 is disposed above the extension of the planned dividing line 13.

[0192] Next, the spindle is rotated to rotate the cutting blade 108. Then, the cutting unit 104 is lowered to a predetermined height, and the chuck table and the cutting unit 104 are moved relative to each other in a direction parallel to the upper surface of the chuck table. As a result, the grinding wheel portion of the rotating cutting blade 108 comes into contact with the workpiece 1, cutting the workpiece 1 and forming division grooves 13a in the workpiece 1 along the intended division lines 13.

[0193] After cutting has been performed along one planned dividing line 13, the chuck table and cutting unit 104 are moved in an indexing feed direction perpendicular to the processing feed direction, and cutting of the workpiece 1 is performed similarly along the other planned dividing lines 13. After cutting has been performed along all of the planned dividing lines 13 along one direction, the chuck table is rotated around an axis perpendicular to the holding surface, and cutting of the workpiece 1 is similarly performed along the planned dividing lines 13 along the other directions. When the workpiece 1 has been cut along all of the planned dividing lines 13 along the workpiece 1, the division of the workpiece 1 is complete.

[0194] The workpiece 1 is divided into a plurality of chips, which are subsequently fixed to the sheet 9. This makes the chips easy to handle. The individual chips are then peeled off from the sheet 9. In the chip manufacturing method shown in FIG. 12, the workpiece 1 that has been ground to high quality is divided into chips, and the manufactured chips are therefore of high quality.

[0195] The structures, methods, etc. according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0196] 1 Workpiece 1a surface 1b back side 3 Protective materials 5 Devices 7 Annular Frame 9 sheets 11 Work Units 13 Planned division line 13a split groove 2 Grinding equipment 4 Foundation 6. Turntable 8 Chuck table 8a Holding surface 8b Frame 8c Porous material 10a, 10b Grinding unit 12a, 12b Spindle motor 14a, 14b Spindle 16a, 16b Wheel mount 18a, 18b Grinding wheels 20a, 20b Grinding wheel 20c circular orbit 22a, 22b Column 24a, 24b Lifting mechanism 24c: Guide rail 26a, 26b Cassette placing table 28a, 28b cassette 30 Wafer transport robot 32 Positioning table 34 Loading Arm 36 Unloading Arm 38 Spinner cleaning device 40,42 Thickness measuring instrument 42a Measuring part 42b Shaft 42c arm 44 Ball screw 46 Nut part 48 Pulse motor 50 Lifting Plate 54 Bottom 56 Rotational drive source 58 Table rotation axis 60 Fixed axis 62 Adjustment axis 64 Adjustment axis 66 Outer circumference 68 center 70 perimeter 72 Grinding Area 74 1st axis 76 2nd axis 90 Controller 92 Grinding control section 94 Necessary adjustment amount calculation section 96 Actual adjustment amount calculation section 98 Adjustment control section 102 Cutting equipment 104 Cutting unit 106 Spindle housing 108 Cutting Blade 110 Cutting water supply nozzle

Claims

1. A grinding device for grinding a workpiece, comprising: a chuck table having a holding surface capable of holding the workpiece and rotatable about a table rotation axis passing through the center of the holding surface; a grinding unit including: a spindle having a grinding wheel, the grinding wheel having grinding stones arranged annularly on its underside, attached to its lower end so that the underside of the grinding wheel faces the holding surface of the chuck table; and a lifting mechanism for relatively raising and lowering the spindle and the chuck table; an inclination adjustment unit that adjusts the inclination of one or both of the table rotation axis and the spindle; a thickness measuring device for measuring the thickness of the workpiece held by the chuck table; a controller; The controller a grinding control unit that rotates the chuck table that holds the workpiece around the table rotation axis and rotates the grinding wheel of the grinding unit around the spindle while bringing the spindle and the chuck table closer together using the lifting mechanism, and brings the grinding stone into contact with the workpiece held by the chuck table to cause the grinding unit to grind the workpiece; a required adjustment amount calculation unit that uses the thickness measuring device to acquire thickness information of the workpiece being ground by the grinding unit, and calculates, based on the thickness information, an adjustment amount required for adjusting the inclination to be performed by the inclination adjustment unit as a required adjustment amount; an actual adjustment amount calculation unit that calculates an actual adjustment amount by multiplying the required adjustment amount calculated by the required adjustment amount calculation unit by an adjustment rate; an adjustment control unit that controls the inclination adjustment unit to adjust the inclination using the actual adjustment amount calculated by the actual adjustment amount calculation unit.

2. 2. The grinding device according to claim 1, wherein the necessary adjustment amount calculation unit calculates the necessary adjustment amount so as to perform PID control of the inclination based on the thickness information.

3. 2. The grinding device according to claim 1, wherein the necessary adjustment amount calculation unit calculates the necessary adjustment amount based on the thickness information so as to P-control the inclination.

4. 4. The grinding device according to claim 1, wherein the actual adjustment amount calculation unit determines the adjustment rate based on the thickness information or the required adjustment amount.

5. 4. The grinding device according to claim 1, wherein the actual adjustment amount calculation unit sets the adjustment rate to a first adjustment rate when the thickness information or a value indicating the required adjustment amount is higher than a selected threshold, and sets the adjustment rate to a second adjustment rate smaller than the first adjustment rate when the value is equal to or lower than the selected threshold.

6. A grinding method for grinding a workpiece in a grinding device including: a chuck table having a holding surface capable of holding a workpiece and rotatable about a table rotation axis passing through the center of the holding surface; and a grinding unit including a spindle having a grinding wheel attached to its lower end, the grinding wheel having grinding stones arranged annularly on its lower surface, the method comprising: a holding step of placing the workpiece on the holding surface of the chuck table and holding the workpiece on the chuck table; a grinding step in which, after the holding step, the chuck table is rotated around the table rotation axis, the spindle is rotated, the chuck table and the spindle are moved relatively in directions in which they approach each other, and the grinding wheel is brought into contact with the workpiece to grind the workpiece, In the grinding step, thickness information of the workpiece being ground is acquired, an adjustment amount required to adjust the inclination of one or both of the table rotation axis and the spindle is calculated as a required adjustment amount based on the thickness information, an actual adjustment amount is calculated by multiplying the required adjustment amount by an adjustment rate, and the inclination is adjusted using the actual adjustment amount.

7. 7. The grinding method according to claim 6, wherein in the grinding step, the necessary adjustment amount is calculated so that the inclination can be PID controlled based on the thickness information.

8. 7. The grinding method according to claim 6, wherein in the grinding step, the necessary adjustment amount is calculated so that the tilt can be P-controlled based on the thickness information.

9. 9. The grinding method according to claim 6, wherein in the grinding step, the adjustment rate is determined based on the thickness information or the required adjustment amount.

10. 9. The grinding method according to claim 6, wherein in the grinding step, when the thickness information or a value indicating the required adjustment amount is higher than a selected threshold, the adjustment rate is set to a first adjustment rate, and when the value is equal to or lower than the selected threshold, the adjustment rate is set to a second adjustment rate smaller than the first adjustment rate.

11. A method for manufacturing a ground workpiece by grinding the workpiece in a grinding device including: a chuck table having a holding surface capable of holding the workpiece and rotatable about a table rotation axis passing through the center of the holding surface; and a grinding unit having a spindle to the lower end of which is mounted a grinding wheel having grinding stones arranged in an annular pattern on its lower surface, placing the workpiece on the holding surface of the chuck table and holding the workpiece with the chuck table; rotating the chuck table around the table rotation axis, rotating the spindle, and relatively moving the chuck table and the spindle in directions in which they approach each other, and bringing the grinding wheel into contact with the workpiece to grind the workpiece, thereby producing a ground workpiece; When the grinding wheel is brought into contact with the workpiece to grind the workpiece, thickness information of the workpiece being ground is obtained, an adjustment amount required to adjust the inclination of one or both of the table rotation axis and the spindle is calculated based on the thickness information as a required adjustment amount, the required adjustment amount is multiplied by an adjustment rate to calculate an actual adjustment amount, and the inclination is adjusted using the actual adjustment amount.

12. A method for manufacturing chips by grinding a workpiece in a grinding device including a chuck table having a holding surface capable of holding a workpiece and rotatable about a table rotation axis passing through the center of the holding surface, and a grinding unit including a spindle having a grinding wheel attached to its lower end, the grinding wheel having grinding stones arranged in an annular pattern on its lower surface, the method comprising: placing the workpiece on the holding surface of the chuck table and holding the workpiece with the chuck table; rotating the chuck table around the table rotation axis and rotating the spindle, and relatively moving the chuck table and the spindle in directions in which they approach each other, thereby bringing the grinding wheel into contact with the workpiece and grinding the workpiece; removing the ground workpiece from the grinding device and dividing it into individual chips; When the grinding wheel is brought into contact with the workpiece to grind the workpiece, thickness information of the workpiece being ground is obtained, an adjustment amount required to adjust the inclination of one or both of the table rotation axis and the spindle is calculated based on the thickness information as a required adjustment amount, the required adjustment amount is multiplied by an adjustment rate to calculate an actual adjustment amount, and the inclination is adjusted using the actual adjustment amount.

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