Grinding apparatus, method for adjusting grinding conditions, and method for grinding a workpiece

Abstract

The present invention provides a grinding apparatus, a method for adjusting grinding conditions, and a grinding method that can appropriately grind a workpiece by controlling the shape of the workpiece after rough grinding based on the state of finish grinding. [Solution] The grinding apparatus comprises a plurality of chuck tables, a first grinding unit having a first spindle with a first grinding wheel for rough grinding attached to its tip, a second grinding unit having a second spindle with a second grinding wheel for finish grinding attached to its tip, a first adjustment mechanism for adjusting the first angle between the rotation axis of the chuck table that holds the workpiece during rough grinding and the first spindle, a first measuring unit for measuring the first state when grinding a workpiece held on the chuck table that holds the workpiece during finish grinding, and a controller, the controller including an adjustment command unit that adjusts the first angle by the first adjustment mechanism based on the first state measured by the first measuring unit.

Description

Technical Field

[0001] The present invention relates to a grinding device, a method for adjusting grinding conditions, and a method for grinding a workpiece.

Background Art

[0002] A device chip used in electrical devices such as mobile phones and PCs (Personal Computers) is manufactured by subjecting a wafer made of a semiconductor material such as silicon to various processes. Specifically, for example, a planned division line is set on the surface of a workpiece such as a wafer, and devices such as ICs (Integrated Circuits) are formed in each of a plurality of regions delimited by this planned division line.

[0003] Then, the workpiece on which the device is formed is ground from the back side by a grinding device or the like to be processed to a predetermined thickness, and then divided along the planned division line by a dividing device (such as a cutting device and a laser processing device). As a result, a plurality of device chips each having a device are manufactured.

[0004] A grinding device for grinding a workpiece has, for example, a chuck table having a holding surface for holding the workpiece and rotatable around a rotation axis intersecting the holding surface, and a grinding unit having a spindle to which a grinding wheel for grinding the workpiece is attached at its tip. The grinding wheel has a grinding stone containing abrasive grains and a binder. By rotating the chuck table and the spindle and bringing the chuck table and the grinding wheel relatively closer to contact the workpiece held by the chuck table and the grinding stone, the workpiece can be ground.

[0005] Furthermore, Patent Document 1 describes a grinding apparatus comprising an adjustment mechanism for adjusting the angle between the rotation axis of the chuck table and the spindle, and a measuring unit for measuring the thickness of a workpiece held by the chuck table. In this grinding apparatus, the thickness of the workpiece is measured at two or more locations by the measuring unit during grinding, and based on these thicknesses, the angle between the rotation axis of the chuck table and the spindle is adjusted by the adjustment mechanism so that the workpiece is ground to a desired shape. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-119123 [Overview of the project] [Problems that the invention aims to solve]

[0007] Grinding of a workpiece using a grinding machine is sometimes performed in two stages: rough grinding and finish grinding. In rough grinding, a grinding wheel containing relatively large abrasive grains is used to grind the workpiece until it is slightly thicker than the finished thickness. In finish grinding, which is performed after rough grinding, a grinding wheel containing relatively small abrasive grains is used to grind the workpiece until it reaches the finished thickness.

[0008] The damage remaining on the workpiece after grinding is greater in rough grinding than in finish grinding, where the abrasive grains in the grinding wheel are smaller. On the other hand, in finish grinding, the amount of material removed per unit time (the volume removed from the workpiece by grinding) is smaller than in rough grinding. Therefore, by grinding the workpiece in two stages, rough grinding and finish grinding, which have these characteristics, it is possible to reduce the damage remaining on the workpiece after grinding while also reducing the time required for grinding.

[0009] As mentioned above, when performing a two-stage grinding process consisting of rough grinding and finish grinding, the shape of the workpiece after rough grinding can affect the finish grinding. For example, as the difference between the thickness at the center and the thickness at the outer edge of the workpiece after rough grinding increases, the amount of material removed during finish grinding will also increase when attempting to flatten it. Therefore, if the difference between the thickness at the center and the thickness at the outer edge of the workpiece is too large, the grinding time will also increase significantly.

[0010] On the other hand, as the difference between the thickness of the central and outer edges of the workpiece after rough grinding decreases, the contact area between the grinding wheel and the workpiece increases during the initial stages of finish grinding. Therefore, if the difference between the thickness of the central and outer edges of the workpiece is too small, especially when the workpiece is made of difficult-to-machine materials such as sapphire, the grinding wheel will not grip the workpiece well, and the workpiece will not be ground properly.

[0011] For these reasons, it was desirable to be able to control the shape of the workpiece after rough grinding, taking into account the state of the finish grinding.

[0012] Therefore, the object of the present invention is to provide a grinding apparatus, a method for adjusting grinding conditions, and a grinding method that can control the shape of a workpiece after rough grinding based on the state of finish grinding, and grind the workpiece appropriately. [Means for solving the problem]

[0013] According to one aspect of the present invention, a grinding apparatus for grinding a workpiece is provided, comprising: a plurality of chuck tables, each having a holding surface for holding the workpiece and rotatable about a rotation axis intersecting the holding surfaces; a first grinding unit having a first spindle with a first grinding wheel mounted at its tip for rough grinding the workpiece; a second grinding unit having a second spindle with a second grinding wheel mounted at its tip for finish grinding the workpiece; a first adjustment mechanism for adjusting a first angle between the rotation axis of the chuck table holding the workpiece and the first spindle during rough grinding; a first measuring unit for measuring a first state when the workpiece held on the chuck table is being ground by the second grinding unit during finish grinding; and a controller for controlling at least the first adjustment mechanism and the first measuring unit, wherein the controller includes an adjustment command unit for adjusting the first angle by the first adjustment mechanism based on the first state measured by the first measuring unit.

[0014] Preferably, the first measuring unit is a first thickness measuring instrument that measures the thickness of the workpiece held by a chuck table that holds the workpiece during finish grinding, and the adjustment command unit adjusts the first angle using the first adjustment mechanism based on the thickness of two or more points on the workpiece measured by the first thickness measuring instrument.

[0015] Preferably, the first measuring unit is a first load measuring instrument that measures the load applied to the chuck table or the second spindle that holds the workpiece during finish grinding, and the adjustment command unit adjusts the first angle using the first adjustment mechanism based on the load measured by the first load measuring instrument.

[0016] Preferably, the controller further includes a first threshold memory unit that stores a first threshold value which is the allowable upper limit of the load, and the adjustment command unit increases the first angle by the first adjustment mechanism when the load measured by the first load measuring instrument is greater than the first threshold value.

[0017] Preferably, the controller further includes a second threshold memory unit that stores a second threshold value which is the allowable lower limit of the load, and the adjustment command unit reduces the first angle by the first adjustment mechanism when the load measured by the first load measuring instrument is less than the second threshold value.

[0018] Preferably, the adjustment command unit further includes a second adjustment mechanism for adjusting the second angle between the rotation axis of the chuck table that holds the workpiece and the second spindle during finish grinding, and a second measuring unit for measuring the second state when the workpiece held on the chuck table that holds the workpiece is being ground by the second grinding unit during finish grinding, wherein the adjustment command unit operates one or both of the first adjustment mechanism and the second adjustment mechanism to adjust one or both of the first angle and the second angle based on one or both of the first state measured by the first measuring unit and the second state measured by the second measuring unit.

[0019] Preferably, the second measuring unit is a second thickness measuring instrument that measures the thickness of the workpiece held by a chuck table that holds the workpiece during rough grinding.

[0020] Preferably, the second measuring unit is a second load measuring instrument that measures the load applied to the chuck table or the first spindle that holds the workpiece during rough grinding.

[0021] According to another aspect of the present invention, there is provided a grinding apparatus for grinding a workpiece, comprising: a chuck table having a holding surface for holding the workpiece and rotatable about a rotation axis intersecting the holding surface; a first grinding unit having a first spindle with a first grinding wheel for rough grinding the workpiece mounted at its tip; a second grinding unit having a second spindle with a second grinding wheel for finish grinding the workpiece mounted at its tip; an adjustment mechanism for adjusting the angle formed by the rotation axis and the first spindle; a measurement unit for measuring the state when the workpiece held by the chuck table is being ground by the second grinding unit; and a controller for controlling at least the adjustment mechanism and the measurement unit. The controller includes an adjustment command for adjusting the angle by the adjustment mechanism based on the state measured by the measurement unit.

[0022] Preferably, the measurement unit is a thickness measuring device for measuring the thickness of the workpiece held by the chuck table, and the adjustment command adjusts the angle by the adjustment mechanism based on the thicknesses of two or more points of the workpiece measured by the thickness measuring device.

[0023] Preferably, the measurement unit is a load measuring device for measuring the load applied to the chuck table or the second spindle, and the adjustment command adjusts the angle by the adjustment mechanism based on the load measured by the load measuring device.

[0024] Preferably, the controller further includes a first threshold value storage unit for storing a first threshold value which is the allowable upper limit of the load, and when the load measured by the measurement unit is greater than the first threshold value, the adjustment command increases the angle by the adjustment mechanism.

[0025] Preferably, the controller further includes a second threshold value storage unit for storing a second threshold value which is the allowable lower limit of the load, and when the load measured by the measurement unit is less than the second threshold value, the adjustment command decreases the angle by the adjustment mechanism.

[0026] According to still another aspect of the present invention, there is provided a method for adjusting grinding conditions for adjusting conditions when grinding a workpiece, the method comprising: a first grinding step of using a first grinding unit having a first spindle with a first grinding wheel mounted at its tip for rough grinding the workpiece, and rough grinding a first workpiece held by a rotating chuck table; after the first grinding step, a second grinding step of using a second grinding unit having a second spindle with a second grinding wheel mounted at its tip for finish grinding the workpiece, and finish grinding the first workpiece held by the rotating chuck table or another rotating chuck table different from the chuck table; and an angle adjustment step of adjusting an angle formed between a rotation axis of the chuck table holding the second workpiece and the first spindle when rough grinding a second workpiece different from the first workpiece later, based on a state measured in the second grinding step.

[0027] Preferably, the state measured in the second grinding step is a thickness of two or more points of the workpiece at the end of the second grinding step, a load applied to the second spindle in the second grinding step, or a load applied to the chuck table holding the first workpiece in the second grinding step.

[0028] According to still another aspect of the present invention, there is provided a method for grinding a workpiece using the above-described method for adjusting grinding conditions, the method further comprising: a third grinding step of using the first grinding unit to rough grind the second workpiece, which is the object of the angle adjustment step and is held by a rotating chuck table, after the angle adjustment step.

Advantages of the Invention

[0029] In the grinding apparatus, grinding apparatus adjustment method, and grinding method according to each aspect of the present invention, the state of the workpiece during finish grinding is measured, and based on this state, the angle between the rotation axis of the chuck table and the spindle during rough grinding of the workpiece is adjusted. Therefore, according to each aspect of the present invention, the shape of the workpiece after rough grinding can be controlled based on the state of finish grinding, and the workpiece can be ground appropriately. [Brief explanation of the drawing]

[0030] [Figure 1] Figure 1 is a perspective view of the grinding machine. [Figure 2] Figure 2 is a cross-sectional view of the chuck table and its surrounding structure. [Figure 3] Figure 3 is an enlarged perspective view of a portion of the chuck table and its surrounding structure. [Figure 4] Figure 4 is a top view of the chuck table support plate. [Figure 5] Figure 5 is a block diagram showing the functional structure of the controller. [Figure 6] Figure 6 is a flowchart showing the flow of the grinding method, including the method for adjusting the grinding conditions. [Figure 7] Figure 7 is a cross-sectional view of the workpiece and chuck table, etc., during the execution of the first grinding step. [Figure 8] Figure 8 is a cross-sectional view of the workpiece and chuck table, etc., during the execution of the second grinding step. [Figure 9] Figures 9(A), 9(B), and 9(C) are cross-sectional views showing examples of workpiece thickness profiles. [Modes for carrying out the invention]

[0031] The configuration example of the grinding apparatus according to this embodiment will be described below with reference to the attached drawings. Figure 1 is a perspective view of the grinding apparatus 2. Note that in Figure 1, some of the components of the grinding apparatus 2 are represented as functional blocks.

[0032] Furthermore, in Figure 1, the direction along the X-axis (X-axis direction, left-right direction of the grinding device 2) and the direction along the Y-axis (Y-axis direction, front-back direction of the grinding device 2) are perpendicular to each other. Also, the direction along the Z-axis (Z-axis direction, up-down direction of the grinding device 2, processing feed direction) is perpendicular to the directions along the X-axis and the Y-axis.

[0033] The configuration example of the grinding apparatus according to this embodiment will be described below with reference to the attached drawings. Figure 1 is a perspective view of the grinding apparatus 2. Note that in Figure 1, some of the components of the grinding apparatus 2 are represented as functional blocks.

[0034] Furthermore, in Figure 1, the direction along the X-axis (X-axis direction, left-right direction of the grinding device 2) and the direction along the Y-axis (Y-axis direction, front-back direction of the grinding device 2) are perpendicular to each other. Also, the direction along the Z-axis (Z-axis direction, up-down direction of the grinding device 2, processing feed direction) is perpendicular to the directions along the X-axis and the Y-axis.

[0035] The grinding device 2 includes a base 4 that supports or accommodates each component that makes up the grinding device 2. An opening 4a is provided on the upper side of the front end of the base 4, and a transport unit (transport mechanism) 6 for transporting the workpiece 11 is provided inside the opening 4a. For example, a transport robot equipped with a robot hand (end effector) capable of holding the workpiece 11 is used as the transport unit 6.

[0036] Cassette installation areas 8a and 8b are provided on both sides of the transport unit 6. Cassettes 10a and 10b, each capable of accommodating multiple workpieces 11, are placed on the cassette installation areas 8a and 8b, respectively. Cassettes 10a and 10b can each accommodate workpieces 11 that are to be processed by the grinding device 2 (workpieces 11 before processing) and / or workpieces 11 after processing (workpieces 11 after processing).

[0037] The workpiece 11 is a disc-shaped wafer (substrate) made of a semiconductor material such as single-crystal silicon, and has a surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other. The workpiece 11 is divided into multiple rectangular regions by multiple streets (planned division lines) arranged in a grid pattern so as to intersect each other. Furthermore, a device (not shown), such as an IC, is formed in each region divided by the streets on the surface 11a side of the workpiece 11.

[0038] For example, by dividing the workpiece 11 along a street using processing equipment such as a cutting device and a laser processing device, multiple device chips, each equipped with a device, can be manufactured. Alternatively, by grinding the workpiece 11 with a grinding device 2 before or after dividing it, a thin device chip can be obtained.

[0039] However, there are no restrictions on the type, material, size, shape, and structure of the workpiece 11. For example, the workpiece 11 may be a wafer made of semiconductors other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. There are also no restrictions on the type, quantity, shape, structure, size, and arrangement of devices formed on the workpiece 11. Furthermore, the workpiece 11 does not need to have streets or devices formed on it.

[0040] An alignment mechanism 12 is provided diagonally behind the opening 4a. The workpieces 11 housed in cassettes 10a and 10b are transported to the alignment mechanism 12 by the transport unit 6. The alignment mechanism 12 then moves a plurality of concentrically arranged pins radially to clamp the workpieces 11 with the pins and position them in a predetermined location.

[0041] A transport unit (transport mechanism, loading arm) 14 for transporting the workpiece 11 is provided adjacent to the alignment mechanism 12. For example, the transport unit 14 is equipped with a suction pad that holds the upper surface of the workpiece 11 by suction. After the workpiece 11, which has been aligned by the alignment mechanism 12, is held by the suction pad, the transport unit 14 rotates the suction pad to transport the workpiece 11 backward.

[0042] A disc-shaped turntable 16 is provided behind the transport unit 14. A rotational drive source (not shown), such as a motor, is connected to the turntable 16 to rotate the turntable 16 around a rotation axis that is substantially parallel to the direction along the Z-axis.

[0043] The turntable 16 is provided with multiple chuck tables 18 capable of holding the workpiece 11, exposed to the upper side. Figure 1 shows an example in which three chuck tables 18 are arranged at approximately equal intervals (120° intervals) along the circumferential direction of the turntable 16. However, there is no limit to the number of chuck tables 18.

[0044] The turntable 16 shown in Figure 1 rotates clockwise and counterclockwise in a plan view. As a result, each chuck table 18 is positioned back at the transport position A, after passing through the transport position A, grinding position (first grinding position, rough grinding position) B, grinding position (second grinding position, finish grinding position) C.

[0045] Figure 2 is a cross-sectional view of the chuck table 18 and its surrounding structure, and Figure 3 is an enlarged perspective view of a part of the chuck table 18 and its surrounding structure. Note that some structures have been omitted or simplified in each figure for the sake of explanation.

[0046] As shown in Figures 2 and 3, each chuck table 18 is supported on the turntable 16 in a rotatable manner via an adjustment mechanism (tilt adjustment mechanism) 90 for adjusting the tilt relative to the turntable 16. The turntable 16 includes a disc-shaped base 16a and a cover 16b positioned above the base 16a, and the adjustment mechanism (tilt adjustment mechanism) 90 is fixed to the base 16a side.

[0047] A spindle 26 for rotating the chuck table 18 is connected to the lower part of each chuck table 18. A predetermined gap (space) is provided between the base 16a and the cover 16b, and the spindle 26 and part of the adjustment mechanism (tilt adjustment mechanism) 90 are housed in this gap.

[0048] A rotational drive source 110, such as a motor, fixed to the base 16a, is connected to the spindle 26. Specifically, as shown in Figure 3, an endless belt 114 is wrapped around the lower part of the spindle 26 and the rotating shaft 112 of the rotational drive source 110, and the spindle 26 is connected to the rotational drive source 110 via the belt 114. When the rotational drive source 110 is driven and the rotating shaft 112 rotates, the rotational force is transmitted to the spindle 26 via the belt 114, causing the chuck table 18 to rotate.

[0049] As shown in Figures 2 and 3, the chuck table 18 includes a disc-shaped frame 20 made of ceramics or metal. A recess 20b with a circular opening at its upper end is formed on the upper surface 20a side of the frame 20. A disc-shaped retaining plate 22 that matches the shape of the recess 20b is fitted into the recess 20b. The retaining plate 22 is made of a porous plate made of a material such as ceramics. A part of the upper surface 20a of the frame 20 and the upper surface 22a of the retaining plate 22 constitute a retaining surface (first retaining surface, second retaining surface) 18a for holding the workpiece 11.

[0050] A suction source (not shown) is connected to the bottom of the recess 20b of the frame 20 via a flow path (not shown) provided inside the frame 20 or a valve (not shown) located outside the frame 20. Therefore, when the valve is opened, negative pressure from the suction source acts on the upper surface 22a of the retaining plate 22 through the flow path, etc. As the suction source, for example, a vacuum pump combining an air supply source and an ejector is used. However, a rotary pump or the like may also be used as the suction source.

[0051] As shown in Figures 2 and 3, the adjustment mechanism 90 has a disc-shaped chuck table support plate 92. A load sensor (first measuring unit, second measuring unit) 120 for detecting loads acting from above is provided on the upper part of the chuck table support plate 92.

[0052] Furthermore, a chuck table 18 is positioned above the load sensor 120 via a thrust bearing 94. In other words, the chuck table support plate 92 of the adjustment mechanism 90 rotatably supports the chuck table 18 via the load sensor 120 and the thrust bearing 94.

[0053] Figure 4 is a top view of the chuck table support plate 92. As shown in Figures 2 and 4, two sets of height adjustment mechanisms 96, which constitute the adjustment mechanism 90, are connected to the lower part of the chuck table support plate 92. Also, as shown in Figure 4, one set of support mechanisms 118 is connected to the lower part of the chuck table support plate 92. The two sets of height adjustment mechanisms 96 and the one set of support mechanisms 118 are arranged, for example, at approximately equal intervals (equal angular intervals). However, the number and arrangement of the height adjustment mechanisms 96 and support mechanisms 118 are not limited to these.

[0054] As shown in Figure 3, each height adjustment mechanism 96 has a cylindrical tube portion 102 inserted into a hole that penetrates the base 16a of the turntable 16. The tube portion 102 is fixed to the base 16a of the turntable 16 by screws 104. A portion of a shaft 100, which is longer than the tube portion 102, is housed in the space inside the tube portion 102. One end (upper end) of the shaft 100 that is exposed from the tube portion 102 is a male thread (not shown). That is, a thread is formed on the side surface of one end of the shaft 100.

[0055] The chuck table support plate 92 has a hole formed through it in the direction of its thickness, and a female threaded nut 106 is fixed to the inside of this hole. The inner side surface of the nut 106 has threads that correspond to the threads on one end of the shaft 100.

[0056] One end of the shaft 100 is inserted inside the nut 106 so that the threads of the nut 106 engage with the threads of the shaft 100, and so that the shaft 100 can rotate relative to the nut 106. In other words, the chuck table support plate 92 is connected to the shaft 100 via the nut 106.

[0057] The other end (lower end) of the shaft 100, exposed from the cylindrical portion 102, is connected to the output shaft of a drive unit 98 for rotating the shaft 100. The drive unit 98 includes a motor 98a that generates rotational force to rotate the shaft 100, and a reduction gear 98b that connects the rotating shaft of the motor 98a to the shaft 100, and is fixed to the cylindrical portion 102 (or base 12b) so as not to rotate. The reduction gear 98b is configured such that the torque of its output shaft is greater than the torque of the rotating shaft of the motor 98a.

[0058] As the motor 98a rotates, the output shaft rotates at a speed corresponding to the reduction ratio of the gearbox 98b, and the shaft 100 rotates together with this output shaft. As the shaft 100 rotates with the threads of the nut 106 engaged with the threads of the shaft 100, the nut 106 moves along the Z-axis relative to the shaft 100. As a result, the chuck table support plate 92 moves along the Z-axis at the position of each height adjustment mechanism 96.

[0059] On the other hand, the support mechanism 118 is configured to support the chuck table support plate 92 without substantially changing the height of the chuck table support plate 92 at that position. Specifically, the support mechanism 118 includes a swivel component that can freely change the orientation of the neck portion relative to the base, and supports the chuck table support plate 92 in such a way that the angle (tilt) of the chuck table support plate 92 is changed in conjunction with the operation of each height adjustment mechanism 96.

[0060] While the height of the chuck table support plate 92 is maintained at the position of the support mechanism 118, the inclination of the chuck table support plate 92 is adjusted by changing the height of the chuck table support plate 92 at the positions of the two sets of height adjustment mechanisms 96. In other words, the angle between the rotation axis 24 of each chuck table 18 and the spindles 44a and 44b of the grinding units 40a and 40b (see Figures 7 and 8) is adjusted.

[0061] As shown in Figure 1, a thickness measuring device (second measuring unit) 80a is provided near grinding position B to measure the thickness of the workpiece 11 held by the chuck table 18 in a non-contact manner. In addition, a thickness measuring device (first measuring unit) 80b is provided near grinding position C to measure the thickness of the workpiece 11 held by the chuck table 18 in a non-contact manner.

[0062] The thickness measuring instruments 80a and 80b each have a shaft portion 82 configured to rotate around a rotation axis (not shown) substantially parallel to the Z axis. The base end of an arm portion 84 extending in a direction substantially parallel to the X and Y axes is fixed to each shaft portion 82. The tip of the arm portion 84 is provided with an irradiation portion (not shown) that irradiates measuring light onto the workpiece 11 held by the chuck table 18, and a light receiving portion (not shown) that receives light reflected by the workpiece 11.

[0063] The light irradiated from the irradiation unit onto the workpiece 11 is, for example, a laser beam and has a wavelength that penetrates the workpiece 11. In this case, the light irradiated from the irradiation unit onto the workpiece 11 is reflected from both the front surface 11a and the back surface 11b of the workpiece 11 held by the chuck table 18 and incident on the light receiving unit. The thickness measuring instruments 80a and 80b can calculate the thickness of the workpiece 11 based on the light reflected from both the front surface 11a and the back surface 11b and incident on the light receiving unit, and output the result to the outside.

[0064] Behind grinding positions B and C, columnar support structures 28 are positioned. A moving unit (moving mechanism) 30 is provided on the front side of each support structure 28. Each moving unit 30 includes a pair of guide rails 32 arranged along the Z-axis. A flat moving plate 34 is mounted on the pair of guide rails 32 so as to be slidable along the guide rails 32.

[0065] A nut portion (not shown) is provided on the rear (back) side of each movable plate 34. A ball screw 36, positioned between a pair of guide rails 32 along the Z-axis, is screwed into this nut portion. A pulse motor 38 for rotating the ball screw 36 is connected to the end of each ball screw 36. When the ball screw 36 is rotated by each pulse motor 38, the corresponding movable plate 34 moves along the Z-axis.

[0066] A grinding unit (first grinding unit, rough grinding unit) 40a is mounted on the movable plate 34 of the movable unit 30a for rough grinding of the workpiece 11. The grinding unit 40a grinds the workpiece 11 which is held by the chuck table 18 positioned at grinding position B.

[0067] The grinding unit 40a includes a hollow, cylindrical housing 42a. The housing 42a is fixed to the front side (surface side) of the movable plate 34 that constitutes the movable unit 30a. The housing 42a houses a cylindrical spindle (first spindle) 44a (see Figure 9) arranged along the Z-axis.

[0068] The tip (lower end) of the spindle 44a is exposed from the housing 42a. A disc-shaped wheel mount 48a made of metal or the like is fixed to the tip of the spindle 44a. A motor 46a that rotates the spindle 44a is connected to the base (upper end) of the spindle 44a. An ammeter (second load measuring instrument, second measuring unit) 56a is connected to the motor 46a. This ammeter 56a measures the current value (load current value) of the current flowing through the motor 46a.

[0069] On the other hand, a grinding unit (second grinding unit, finish grinding unit) 40b is mounted on the movable plate 34 of the movable unit 30b to perform finish grinding on the workpiece 11. The grinding unit 40b grinds the workpiece 11 which is held by the chuck table 18 positioned at grinding position C.

[0070] The structure of the grinding unit 40b is the same as that of the grinding unit 40a. Specifically, the grinding unit 40b includes a hollow, cylindrical housing 42b. The housing 42b is fixed to the front side (surface side) of the movable plate 34. The housing 42b houses a cylindrical spindle (second spindle) 44b (see Figure 10) arranged along the Z-axis.

[0071] The tip (lower end) of the spindle 44b is exposed from the housing 42b. A disc-shaped wheel mount 48b made of metal or the like is fixed to the tip of the spindle 44b. A motor 46b that rotates the spindle 44b is connected to the base (upper end) of the spindle 44b. An ammeter (first load measuring instrument, first measuring unit) 56b is connected to the motor 46b. This ammeter 56b measures the current value (load current value) of the current flowing through the motor 46b.

[0072] A grinding wheel (first grinding wheel, rough grinding wheel) 50a for rough grinding is mounted on the underside of the wheel mount 48a of the grinding unit 40a. On the other hand, a grinding wheel (finishing grinding wheel, second grinding wheel) 50b for finish grinding is mounted on the underside of the wheel mount 48b of the grinding unit 40b.

[0073] The grinding wheels 50a and 50b are machining tools that can be attached to and removed from the wheel mounts 48a and 48b. For example, they are fixed to the wheel mounts 48a and 48b by fasteners such as fastening bolts and are used for grinding the workpiece 11. Thus, the grinding wheels 50a and 50b are mounted on the tips of the spindles 44a and 44b.

[0074] The grinding wheel 50a has an annular wheel base 52a (see Figure 7) and a plurality of grinding wheels 54a (see Figure 7) fixed to the lower surface of the wheel base 52a. Similarly, the grinding wheel 50b has an annular wheel base 52b (see Figure 8) and a plurality of grinding wheels 54b (see Figure 8) fixed to the lower surface of the wheel base 52b.

[0075] The grinding wheels 54a and 54b include abrasive grains, such as diamond or cBN (cubic boron nitride), and a binder (bonding material) such as a metal bond, resin bond, or vitrified bond to fix the abrasive grains. Generally, the average particle size of the abrasive grains contained in the grinding wheel 54a for rough grinding is smaller than the average particle size of the abrasive grains contained in the grinding wheel 54b for finish grinding.

[0076] However, the materials of the abrasive grains and binders constituting the grinding wheels 54a and 54b, the particle size of the abrasive grains, etc., are not limited to these and are selected so as to enable proper grinding of the workpiece 11. Furthermore, there are no restrictions on the shape, structure, size, quantity, arrangement, etc., of the grinding wheels 54a and 54b.

[0077] The moving unit 30a shown in Figure 1 raises and lowers the grinding unit 40a along the Z-axis, thereby bringing the chuck table 18 and the grinding wheel 50a, which are positioned at grinding position B, closer together and further apart along the Z-axis. With the chuck table 18 and the grinding wheel 50a rotating, the grinding wheel 54a comes into contact with the workpiece 11 on the chuck table 18, causing the workpiece 11 to be roughly ground.

[0078] Similarly, the moving unit 30b raises and lowers the grinding unit 40b along the Z-axis, thereby bringing the chuck table 18 and the grinding wheel 50b, which are positioned at the grinding position C, closer together and further apart along the Z-axis. With the chuck table 18 and the grinding wheel 50b rotating, the grinding wheel 54b comes into contact with the workpiece 11 on the chuck table 18, thereby performing finish grinding on the workpiece 11.

[0079] As shown in Figure 1, a transport unit (transport mechanism, unloading arm) 72 for transporting the workpiece 11 is provided at a position adjacent to the transport unit 14 in the X-axis direction. For example, the transport unit 72 is equipped with a suction pad that holds the upper surface of the workpiece 11 by suction. The transport unit 72 holds the ground workpiece 11, which is held by the chuck table 18 located at transport position A, with the suction pad, and then rotates the suction pad to transport the workpiece 11 forward.

[0080] A cleaning unit (cleaning mechanism) 74 for cleaning the workpiece 11 is provided on the front side of the transport unit 72. The cleaning unit 74 cleans the workpiece 11 after grinding, which has been transported from the chuck table 18 by the transport unit 72. For example, the cleaning unit 74 includes a spinner table that holds and rotates the workpiece 11, and a nozzle that supplies a cleaning liquid (such as pure water) to the workpiece 11 held by the spinner table.

[0081] Furthermore, the grinding apparatus 2 includes a controller (control unit, control unit, control device) 60 connected to each component that constitutes the grinding apparatus 2 (transport unit 6, alignment mechanism 12, transport unit 14, turntable 16, chuck table 18, thickness measuring instruments 80a, 80b, adjustment mechanism 90, load detector 120, moving units 30a, 30b, grinding units 40a, 40b, transport unit 72, and cleaning unit 74, etc.). The controller 60 controls the operation of the grinding apparatus 2 by outputting control signals to each component of the grinding apparatus 2.

[0082] For example, the controller 60 is composed of a computer and includes a processing unit 62 that performs calculations necessary for the operation of the grinding machine 2, and a storage device 64 that stores various information (data, programs, etc.) used for the operation of the grinding machine 2. The processing unit 62 is typically a CPU (Central Processing Unit) and performs various processes necessary to control the elements described above.

[0083] The storage device 64 includes, for example, a main memory such as DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a hard disk drive or flash memory. The functions of the controller 60 are realized, for example, by the operation of the processing unit 62 according to a program (software) stored in the storage device 64. However, the controller 60 may be implemented by hardware alone.

[0084] Figure 5 is a block diagram showing the functional structure of the controller 60. The controller 60 includes an adjustment command unit 66 that controls the operation of the adjustment mechanism 90 described above, a first threshold value storage unit 68 that stores a first threshold value, and a second threshold value storage unit 70 that stores a second threshold value.

[0085] The adjustment command unit 66 can control the operation of the adjustment mechanism 90 connected to the chuck table 18 positioned at the grinding position B on the rough grinding side, based on the thickness of two or more points on the workpiece 11 at the time when finish grinding is started (before or after finish grinding is started), as measured by the thickness measuring instrument (first measuring unit) 80b on the finish grinding side.

[0086] For example, if the workpiece 11 at the start of finish grinding is deemed to have a thickness profile characterized by the difference between the thickness on the outer circumference and the thickness on the center being greater than the upper limit of what is permissible, the adjustment command unit 66 controls the adjustment mechanism 90 so that the angle (first angle) between the rotation axis 24 of the chuck table 18 positioned at grinding position B and the spindle (first spindle) 40a of the grinding unit 40a becomes smaller.

[0087] On the other hand, if the workpiece 11 at the time the finish grinding is started is deemed to have a thickness profile characterized by the difference between the thickness on the outer circumference and the thickness on the center being smaller than the lower limit of what is permissible, the adjustment command unit 66 controls the adjustment mechanism 90 so that the angle (first angle) between the rotation axis 24 of the chuck table 18 positioned at grinding position B and the spindle (first spindle) 40a of the grinding unit 40a becomes larger.

[0088] Furthermore, the adjustment command unit 66 can control the operation of the adjustment mechanism 90 connected to the chuck table 18 located at the grinding position B on the rough grinding side, based, for example, the current value measured by the ammeter (first measuring unit) 56b on the finish grinding side, or the load measured by the load detector (first measuring unit) 120 located at the grinding position C on the finish grinding side. In this case, the adjustment command unit 66 controls the operation of the adjustment mechanism 90 using the first threshold and / or second threshold described above.

[0089] The first threshold value stored in the first threshold value storage unit 68 is, for example, the upper limit of the allowable range of the current value measured by the ammeter 56b, or the upper limit of the allowable range of the load (the load applied to the chuck table (second chuck table) 18 at grinding position C) measured by the load detector 120 located at grinding position C.

[0090] The second threshold value stored in the second threshold value storage unit 70 is, for example, the lower limit of the allowable range of the current value measured by the ammeter 56b, or the lower limit of the allowable range of the load (the load applied to the chuck table (second chuck table) 18 at the grinding position C) measured by the load detector 120 located at the grinding position C.

[0091] When the "upper limit of the allowable range of current values" is adopted as the first threshold, the adjustment command unit 66 compares the current value measured by the ammeter 56b with the first threshold stored in the first threshold storage unit 68. Similarly, when the "lower limit of the allowable range of current values" is adopted as the second threshold, the adjustment command unit 66 compares the current value measured by the ammeter 56b with the second threshold stored in the second threshold storage unit 70.

[0092] Furthermore, if the "upper limit of the allowable range of load" is adopted as the first threshold, the adjustment command unit 66 compares the load measured by the load detector 120 located at grinding position C (the load applied to the chuck table (second chuck table) 18 at grinding position C) with the first threshold stored in the first threshold storage unit 68.

[0093] Similarly, when the "lower limit of the allowable load range" is adopted as the second threshold, the adjustment command unit 66 compares the load measured by the load detector 120 located at grinding position C (the load applied to the chuck table (second chuck table) 18 at grinding position C) with the second threshold stored in the second threshold storage unit 70.

[0094] If the current value measured by the ammeter 56a or the load measured by the load detector 120 exceeds the first threshold, the adjustment command unit 66 controls the adjustment mechanism 90 so that, for example, the angle (first angle) between the rotation axis 24 of the chuck table 18 positioned at grinding position B and the spindle (first spindle) 40a of the grinding unit 40a increases.

[0095] On the other hand, if the current value measured by the ammeter 56a or the load measured by the load detector 120 falls below the first threshold, the adjustment command unit 66 controls the adjustment mechanism 90 so that, for example, the angle (first angle) between the rotation axis 24 of the chuck table 18 positioned at grinding position B and the spindle (first spindle) 40a of the grinding unit 40a becomes smaller.

[0096] In this way, the adjustment command unit 66 can adjust the angle (first angle) between the rotation axis 24 of the chuck table 18 positioned at the grinding position B on the rough grinding side and the spindle (first spindle) 40a of the grinding unit 40a on the rough grinding side, based on the condition on the finish grinding side (the thickness of two or more points of the workpiece 11 at the time of finish grinding as measured by the thickness measuring instrument 80b, the current value measured by the ammeter 56b, or the load measured by the load detector 120 on the finish grinding side).

[0097] However, the adjustment command unit 66 may be configured to adjust the angle (first angle) between the rotation axis 24 of the chuck table 18 positioned at the grinding position B on the rough grinding side and the spindle (first spindle) 44a of the grinding unit 40a on the rough grinding side, based on the condition on the rough grinding side (the thickness of two or more points on the workpiece 11 before or after rough grinding as measured by the thickness measuring instrument 80a, the current value measured by the ammeter 56a, or the load measured by the load detector 120 on the rough grinding side).

[0098] Furthermore, the adjustment command unit 66 may be configured to control an adjustment mechanism 90 connected to a chuck table (second chuck table) 18 positioned at the grinding position C on the finish grinding side. In other words, the adjustment command unit 66 may be configured to adjust the angle (first angle) between the rotation axis 24 of the chuck table 18 positioned at the grinding position C on the finish grinding side and the spindle (second spindle) 44b of the grinding unit 40b on the finish grinding side.

[0099] In this case, the adjustment command unit 66 may be configured to adjust the angle (second angle) between the rotation axis 24 of the chuck table 18 positioned at the grinding position C on the finish grinding side and the spindle (second spindle) 44b of the grinding unit 40b on the finish grinding side, based on the condition on the rough grinding side (the thickness of two or more points on the workpiece 11 before or after rough grinding as measured by the thickness measuring instrument 80a, the current value measured by the ammeter 56a, or the load measured by the load detector 120 on the rough grinding side).

[0100] Furthermore, the adjustment command unit 66 may be configured to adjust the angle (second angle) between the rotation axis 24 of the chuck table 18 positioned at the grinding position C on the finish grinding side and the spindle (second spindle) 44b of the grinding unit 40b on the finish grinding side, based on the condition on the finish grinding side (the thickness of two or more points of the workpiece 11 at the time of finish grinding as measured by the thickness measuring instrument 80b, the current value measured by the ammeter 56b, or the load measured by the load detector 120 on the finish grinding side).

[0101] In any case, it is desirable that "criteria for judgment according to the thickness profile of the workpiece 11" and "threshold values ​​(such as "upper limit of the allowable range of current value", "lower limit of the allowable range of current value", "upper limit of the allowable range of load", "lower limit of the allowable range of load")" be set so that the adjustment command unit 66 can appropriately control the operation of each adjustment mechanism 90.

[0102] Using the grinding apparatus 2 described above, the grinding condition adjustment method and grinding method according to this embodiment are performed. Next, the grinding condition adjustment method and grinding method according to this embodiment will be explained. Figure 6 is a flowchart showing the flow of the grinding method, including the grinding condition adjustment method.

[0103] As shown in Figure 6, the grinding method according to this embodiment comprises a first grinding step S1, a second grinding step S2, an angle adjustment step S3, a third grinding step S4, and a fourth grinding step S5. The first grinding step S1, the second grinding step S2, and the angle adjustment step S3 constitute the grinding condition adjustment method S10 according to this embodiment. Each step will be described below. In this embodiment, each step constituting the grinding method and the grinding condition adjustment method S10 is performed based on a command from the controller 60.

[0104] First, as preparation for executing the first grinding step S1, the workpiece (first workpiece) 11 is held by the holding surface 18a of the chuck table 18 and positioned at grinding position B. Specifically, a cassette 10a or cassette 10b containing multiple workpieces 11 is placed on the cassette installation area 8a or cassette installation area 8b. Next, the transport unit 6 transports the workpieces 11 from the cassette 10a or cassette 10b to the alignment mechanism 12, where the alignment mechanism 12 aligns the workpieces 11.

[0105] Then, the workpiece 11 is transported by the transport unit 14 to the chuck table 18 located at transport position A, and the workpiece 11 is held by this chuck table 18. Subsequently, the turntable 16 rotates, and the chuck table 18 holding the workpiece 11 moves from transport position A to grinding position B. As a result, the chuck table 18 holding the workpiece 11 is positioned at grinding position B.

[0106] Next, the first grinding step (rough grinding step) S1 is performed. Figure 7 is a cross-sectional view of the workpiece 11 and the chuck table 18, etc., during the execution of the first grinding step S1. As shown in Figure 7, in the first grinding step S1, the grinding wheel 50a for rough grinding is rotated by rotating the spindle (first spindle) 44a of the grinding unit 40a with a rotational drive source. In addition, the chuck table 18 at grinding position B is rotated around the rotation axis 24 by rotating the spindle 26 with the rotational drive source.

[0107] With the grinding wheel 50a and the chuck table 18 rotating in this manner, the controller 60 lowers the moving plate 34 of the moving unit 30a along the guide rail 32. As a result, the lower surface of the grinding wheel 54a comes into contact with the back surface 11b of the workpiece 11, and the workpiece 11 is ground from the back surface 11b side (rough grinding).

[0108] For rough grinding, the grinding conditions are as follows: For example, the rotational speed of the spindle 44a that rotates the grinding wheel 50a is set to 1000 rpm or more and 7000 rpm or less, typically set to 3200 rpm. The rotational speed of the chuck table 18 is set to 100 rpm or more and 700 rpm or less, typically set to 300 rpm. The relative movement speed (feed rate) of the grinding wheel 50a and the chuck table 18 in the direction perpendicular to the back surface 11b of the workpiece 11 is set to 1 μm / s or more and 6 μm / s or less, typically set to 3 μm / s. The first grinding step S1 is completed when the workpiece 11 has been processed to a predetermined thickness.

[0109] In parallel with this first grinding step S1, a workpiece (second workpiece) 11, separate from the workpiece (first workpiece) 11 described above, is transported from cassette 10a or cassette 10b to the alignment mechanism 12 and aligned. The aligned workpiece 11 is then transported to a chuck table 18 located at transport position A, and the workpiece 11 is held by this chuck table 18.

[0110] After the first grinding step S1 is completed, the turntable 16 rotates in preparation for performing the second grinding step (finish grinding step) S2, etc. Specifically, the turntable 16 rotates so that the chuck table 18 located at grinding position B moves to grinding position C, and the chuck table 18 located at transport position A moves to grinding position B. As a result, the chuck table 18 holding the roughly ground workpiece (first workpiece) 11 is placed at grinding position C, and the chuck table 18 holding the unground workpiece (second workpiece) 11 is placed at grinding position B.

[0111] Then, the second grinding step S2 is performed. Figure 8 is a cross-sectional view of the workpiece 11 and the chuck table 18, etc., during the execution of the second grinding step S2. As shown in Figure 8, in the second grinding step S2, the grinding wheel 50b is rotated by rotating the spindle (second spindle) 44b of the grinding unit 40b with a rotational drive source. In addition, the chuck table 18 at grinding position C is rotated around the rotation axis 24 by rotating the spindle 26 with the rotational drive source.

[0112] With the grinding wheel 50b and the chuck table 18 rotating in this manner, the controller 60 lowers the moving plate 34 of the moving unit 30b along the guide rail 32. As a result, the lower surface of the grinding wheel 54b comes into contact with the back surface 11c of the workpiece 11, and the workpiece 11 is ground from the back surface 11c side (finish grinding). The back surface 11c is the surface exposed when the back surface 11b side of the workpiece 11 is ground in the first grinding step S1.

[0113] For the finish grinding conditions, for example, the rotational speed of the spindle 44b that rotates the grinding wheel 50b is set to 1000 rpm or more and 7000 rpm or less, typically 3200 rpm. The rotational speed of the chuck table 18 is set to 100 rpm or more and 700 rpm or less, typically 300 rpm. The relative movement speed (feed rate) of the grinding wheel 50a and the chuck table 18 in the direction perpendicular to the back surface 11c of the workpiece 11 is set to 0.1 μm / s or more and 0.66 μm / s or less, typically 0.1 μm / s. The second grinding step S2 is completed when the workpiece 11 has been processed to a predetermined finish thickness.

[0114] In this embodiment, in the second grinding step S2, the current value corresponding to the load applied to the spindle 44b is measured by the ammeter (first measuring unit) 56b. Alternatively, the load corresponding to the load applied to the chuck table 18 is measured by the load detector (first measuring unit) 120. Alternatively, the thickness of the workpiece 11 at the time when finish grinding is started (immediately before or immediately after finish grinding is started) is measured by the thickness measuring instrument (first measuring unit) 80b.

[0115] In other words, in this embodiment, during the second grinding step S2, the state related to finish grinding (first state) (current value, load, and thickness of the workpiece 11 at the time finish grinding is started) is measured. The measured state information is transmitted to the controller 60.

[0116] Next, the angle adjustment step S3 is performed. In the angle adjustment step S3, the tilt of the chuck table 18, which is positioned at grinding position B, the rough grinding side, is adjusted by the adjustment mechanism (first adjustment mechanism) 90 based on the finish grinding state (first state) measured in the second grinding step S2.

[0117] More specifically, the adjustment command unit 56 of the controller 60 adjusts the inclination of the rough grinding side chuck table 18 using the adjustment mechanism 90 based on at least one of the received current value, load, and thickness of the workpiece 11. This adjusts the angle (first angle) between the rotation axis 24 of the rough grinding side chuck table 18 and the spindle 44a of the rough grinding side grinding unit 40a. By adjusting the first angle, the thickness profile of the workpiece 11 after rough grinding can be changed. Note that if it is not necessary to adjust the first angle, the angle adjustment step S3 may be omitted.

[0118] Figures 9(A), 9(B), and 9(C) are cross-sectional views showing examples of thickness profiles of workpieces after rough grinding. Using the thickness profile of workpiece 11 shown in Figure 9(A) as a reference, the workpiece 11 shown in Figure 9(B) has a large difference between the thickness on the outer circumference and the thickness at the center. Conversely, the workpiece 11 shown in Figure 9(C) has a small difference between the thickness on the outer circumference and the thickness at the center.

[0119] For example, as shown in Figure 9(C), if the difference between the thickness of the outer circumference and the thickness of the center of the workpiece 11 after rough grinding is too small, the contact area between the workpiece 11 and the grinding wheel 54b becomes too large in the initial stages of finish grinding. As a result, the grinding wheel 54b does not grip the workpiece 11 well, making it difficult to proceed with finish grinding of the workpiece 11.

[0120] Therefore, in such cases, the adjustment command unit 66 of the controller 60 activates the adjustment mechanism 90 on the rough grinding side and adjusts the angle (first angle) between the rotation axis 24 of the chuck table 18 on the rough grinding side and the spindle 44a of the grinding unit 40a to be greater than a predetermined value.

[0121] Specifically, the adjustment command unit 66 adjusts the first angle using the rough grinding adjustment mechanism 90 when the contact area between the workpiece 11 and the grinding wheel 54b is too large, that is, when the current value corresponding to the load applied to the spindle 44b or the load corresponding to the load applied to the chuck table 18 is greater than the first threshold value.

[0122] Alternatively, the adjustment command unit 66 adjusts the first angle to be greater than a predetermined value if the workpiece 11 has a thickness profile that deviates from the standard as shown in Figure 9(C) at the time when finish grinding is started. In other words, the adjustment command unit 66 adjusts the first angle using the rough grinding side adjustment mechanism 90 based on the thickness of two or more points on the workpiece 11 measured by the thickness measuring instrument (first measuring unit) 80b.

[0123] This makes it possible to achieve a thickness profile in the rough grinding of the next workpiece (second workpiece) 11, where the difference between the thickness on the outer circumference and the thickness on the center is sufficiently large, as shown in Figure 9(A). In other words, it is possible to improve the grip of the grinding wheel 54b on the workpiece 11 and facilitate the finish grinding of the workpiece 11.

[0124] On the other hand, if the difference between the thickness of the outer circumference and the thickness of the center of the workpiece 11 after rough grinding is too large, as shown in Figure 9(B), the contact area between the workpiece 11 and the grinding wheel 54b becomes too small in the initial stages of finish grinding. In this case, the grinding wheel 54b grips the workpiece 11 well, so the finish grinding of the workpiece 11 proceeds appropriately.

[0125] However, if the difference between the thickness of the outer circumference and the thickness of the center of the workpiece 11 is too large, the grinding volume will increase when trying to make the thickness of the workpiece 11 equal on both the outer circumference and the center during finish grinding, resulting in an excessively long grinding time. In other words, the processing efficiency will decrease.

[0126] Therefore, in such cases, the adjustment command unit 66 of the controller 60 activates the adjustment mechanism 90 on the rough grinding side and adjusts the angle (first angle) between the rotation axis 24 of the chuck table 18 on the rough grinding side and the spindle 44a of the grinding unit 40a to be smaller than a predetermined value.

[0127] Specifically, the adjustment command unit 66 adjusts the first angle using the rough grinding adjustment mechanism 90 when the contact area between the workpiece 11 and the grinding wheel 54b is too small, that is, when the current value corresponding to the load applied to the spindle 44b or the load corresponding to the load applied to the chuck table 18 is smaller than the second threshold value.

[0128] Alternatively, the adjustment command unit 66 adjusts the first angle to a value smaller than a predetermined value if the workpiece 11 has a thickness profile that deviates from the standard as shown in Figure 9(B) at the time when finish grinding is started. In other words, the adjustment command unit 66 adjusts the first angle using the rough grinding adjustment mechanism 90 based on the thickness of two or more points on the workpiece 11 measured by the thickness measuring instrument (first measuring unit) 80b.

[0129] This makes it possible to achieve a thickness profile in the rough grinding of the next workpiece (second workpiece) 11 where the difference between the thickness on the outer circumference and the thickness on the center side is sufficiently small, as shown in Figure 9(A). In other words, it is possible to reduce the grinding volume when trying to make the thickness of the workpiece 11 equal on the outer circumference and the center side during finish grinding, thereby shortening the time required for finish grinding.

[0130] In the angle adjustment step S3, the angle (first angle) between the rotation axis 24 of the chuck table 18 on the rough grinding side and the spindle 44a of the grinding unit 40a on the rough grinding side is adjusted, after which the third grinding step (rough grinding step) S4 is performed to roughly grind the workpiece (second workpiece) 11.

[0131] The grinding method and conditions are the same as when the workpiece (first workpiece) 11 is roughly ground in the first grinding step S1 described above. By performing the angle adjustment step S3 described above, after the third grinding step (rough grinding step) S4, a workpiece (second workpiece) 11 having a shape suitable for finish grinding to be performed in the next fourth grinding step (finish grinding step) S5 is obtained.

[0132] After the third grinding step S4 is completed, the turntable 16 rotates in preparation for performing the fourth grinding step (finish grinding step) S5, etc. Specifically, the turntable 16 rotates so that the chuck table 18 located at grinding position B moves to grinding position C, and the chuck table 18 located at grinding position C moves to transport position A.

[0133] As a result, the chuck table 18 holding the workpiece (second workpiece) 11 after rough grinding is placed at grinding position C, and the chuck table 18 holding the workpiece (first workpiece) 11 after finish grinding is placed at transport position A. After the turntable 16 has rotated, the adjustment command unit 66 of the controller 60 adjusts the angle between the rotation axis 24 of the chuck table 18 located at grinding position C and the spindle 44b of the grinding unit 40b (see Figures 7 and 8) to a state suitable for finish grinding using the adjustment mechanism 90.

[0134] Then, the fourth grinding step S5 is performed. Specifically, finish grinding is performed on the workpiece (second workpiece) 11 held by the chuck table 18 positioned at grinding position C. The grinding method and conditions are the same as those of the second grinding step S2 described above. Since the workpiece (second workpiece) 11 has a thickness profile suitable for performing the fourth grinding step S5, the workpiece (second workpiece) 11 is finish ground quickly and appropriately by the fourth grinding step S5.

[0135] In parallel with this fourth grinding step S5, the workpiece (first workpiece) 11 described above is transported by the transport unit 72 from the chuck table 18 at transport position A to the cleaning unit 74, where it is cleaned. After cleaning, the workpiece 11 is transported by the transport unit 6 and placed back into cassette 10a or cassette 10b.

[0136] In the fourth grinding step S5, once the finish grinding of the workpiece (second workpiece) 11 is complete, the turntable 16 rotates. Specifically, the turntable 16 rotates so that the chuck table 18, which is located at grinding position C, moves to transport position A. As a result, the chuck table 18, which holds the workpiece (second workpiece) 11 after finish grinding, is placed at transport position A.

[0137] The workpiece (second workpiece) 11 is then transported by the transport unit 72 from the chuck table 18 at transport position A to the cleaning unit 74, where it is cleaned. After cleaning, the workpiece 11 is transported by the transport unit 6 and placed back into cassette 10a or cassette 10b. This concludes the flow of the grinding method according to this embodiment.

[0138] In the above-described embodiment, the angle between the rotation axis 24 of the chuck table on the rough grinding side and the spindle (first spindle) 44a of the grinding unit 40a is adjusted based on the state during finish grinding (first state). However, the angle between the rotation axis 24 of the chuck table 18 on the finish grinding side and the spindle (second spindle) 44b of the grinding unit 40b may be adjusted based on the state during rough grinding (second state).

[0139] For example, if the workpiece 11 is made of silicon or the like, and its exposed surface is oxidized to form an oxide film, then rough grinding of the workpiece 11 is performed using a grinding wheel 54a that is not optimized for grinding this oxide film. In such cases, the grinding may not proceed properly, and defects such as clogged or chipped teeth may occur on the grinding wheel 54a.

[0140] When such a malfunction occurs, the grinding wheel 54a acts as if the particle size of its abrasive grains has been substantially reduced, and the surface roughness of the workpiece 11 being ground tends to be lower than the target surface roughness. In other words, the ground surface tends to become flatter. As a result, the grip of the grinding wheel 54b on the workpiece 11 may be poor in the initial stages of finish grinding, and grinding may not proceed properly.

[0141] Therefore, in such cases, the adjustment command unit 66 of the controller 60 activates the adjustment mechanism 90 on the finish grinding side and adjusts the angle (second angle) between the rotation axis 24 of the chuck table 18 on the finish grinding side and the spindle 44b of the grinding unit 40b so that the initial contact area between the workpiece 11 and the grinding wheel 54b during finish grinding is sufficiently small.

[0142] Specifically, the adjustment command unit 66 adjusts the second angle using the adjustment mechanism 90 on the finish rough grinding side when it can be determined that a defect such as clogged or chipped teeth has occurred in the grinding wheel 54a on the rough grinding side, that is, when the current value corresponding to the load applied to the spindle 44a, or the load corresponding to the load applied to the chuck table 18 on the rough grinding side, is greater than an arbitrary threshold. Alternatively, the adjustment command unit 66 adjusts the second angle using the adjustment mechanism 90 on the finish rough grinding side when the variation in the thickness of the workpiece 11 at the completion of rough grinding is smaller than a reference value.

[0143] The current value corresponding to the load applied to the spindle 44a, the load corresponding to the load applied to the chuck table 18 on the rough grinding side, and the thickness of the workpiece 11 when rough grinding is completed are measured by an ammeter (second load measuring device, second measuring unit) 56a, a load detector (second load measuring device, second measuring unit) 120 on the rough grinding side, and a thickness measuring device (second measuring unit) 80a, respectively.

[0144] As a result, in the initial stages of finish grinding of the workpiece 11, the contact area between the workpiece 11 and the grinding wheel 54b becomes sufficiently small, and the grinding wheel 54b grips the workpiece 11 well, so that the finish grinding proceeds appropriately. In this case, it is desirable that the second angle be readjusted at some point during the finish grinding so that the workpiece 11 is processed to a uniform thickness by the finish grinding.

[0145] Similarly, in situations like those described above where defects such as clogged or chipped teeth occur in the grinding wheel 54a, the workpiece 11 after rough grinding tends to exhibit a thickness profile with a large difference between the thickness on the outer circumference and the thickness on the center side, as shown in Figure 9(B). Therefore, the second angle may be adjusted in the adjustment mechanism 90 on the finish rough grinding side in order to eliminate variations in the thickness of the workpiece 11 after finish grinding.

[0146] As described above, in the grinding apparatus, grinding apparatus adjustment method, and grinding method according to the above-described embodiment, the state of the workpiece during finish grinding is measured, and based on this state, the angle between the rotation axis of the chuck table and the spindle during rough grinding of the workpiece is adjusted. This allows the shape of the workpiece after rough grinding to be controlled based on the state during finish grinding, and the workpiece to be ground appropriately.

[0147] It should be noted that the present invention is not limited to the embodiments described above and can be implemented with various modifications. For example, in the embodiments described above, the first angle is adjusted by adjusting the tilt of the chuck table 18 by the adjustment mechanism 90, but the first angle may also be adjusted by adjusting the tilt of the spindle 44a. Similarly, the second angle may be adjusted by adjusting the tilt of the spindle 44b.

[0148] Furthermore, in the above-described embodiment, the method for adjusting grinding conditions and the grinding method are performed using a grinding apparatus 2 equipped with multiple chuck tables 18. However, the method for adjusting grinding conditions and the grinding method according to the present invention may also be performed using a grinding apparatus equipped with only one chuck table.

[0149] In this case, the grinding apparatus comprises a first grinding unit fitted with a first grinding wheel for rough grinding, and a second grinding unit fitted with a second grinding wheel for finish grinding. Ammeters are connected to the motors that rotate the spindles (first spindle and second spindle) of each grinding unit. The grinding apparatus also has at least one thickness measuring instrument and one load sensor.

[0150] In this modified example, the method for adjusting the grinding conditions and the grinding method are performed in the following steps, for example. First, the workpiece (first workpiece) 11 is placed on the chuck table 18 and held by the chuck table 18. Then, a first grinding step (rough grinding step) S1 is performed on the workpiece (first workpiece) 11, and then a second grinding step (finish grinding step) S2 is performed on the workpiece (first workpiece) 11.

[0151] In other words, rough grinding and finish grinding of the workpiece (first workpiece) 11 are performed in this order. In the second grinding step, as in the embodiment described above, the state during finish grinding (first state) (current value, load, and thickness of the workpiece 11 at the start of finish grinding) is measured.

[0152] An angle adjustment step S3 is performed after the second grinding step is completed and before the next unground workpiece (second workpiece) 11 is rough-ground. Specifically, the angle adjustment step S3 is performed before the workpiece (first workpiece) 11 is removed from the chuck table 18, after the workpiece (first workpiece) 11 has been removed from the chuck table 18 but before the workpiece (second workpiece) 11 is loaded into the chuck table, or after the workpiece (second workpiece) 11 has been loaded into the chuck table.

[0153] In the angle adjustment step S3, the angle between the rotation axis of the chuck table and the first spindle of the first grinding unit on the rough grinding side is adjusted based on the first state described above. More specifically, the tilt of the chuck table is adjusted based on the first state. However, the tilt of the first spindle on the rough grinding side may also be adjusted based on the first state. Furthermore, if it is not necessary to adjust the angle between the rotation axis of the chuck table and the first spindle of the first grinding unit on the rough grinding side, the angle adjustment step S3 may be omitted.

[0154] Subsequently, a third grinding step (rough grinding step) S4 is performed on the workpiece (second workpiece) 11. After the third grinding step S4, a fourth grinding step (finish grinding step) S5 is performed on the workpiece (second workpiece) 11. However, if the tilt of the chuck table has been adjusted in the angle adjustment step S3, the tilt of the check table is adjusted again after the third grinding step S4 and before the fourth grinding step S5 to a state suitable for finish grinding.

[0155] In this modified example, the angle between the rotation axis of the chuck table and the first spindle of the first grinding unit on the rough grinding side is adjusted based on the state during finish grinding (first state). However, the angle between the rotation axis of the chuck table and the second spindle of the second grinding unit on the finish grinding side may be adjusted based on the state during rough grinding (second state).

[0156] In each of the above-described modifications, the same effects as those of the grinding apparatus, the method for adjusting the grinding apparatus, and the grinding method according to the above-described embodiment can be obtained.

[0157] Furthermore, the embodiments and structures, methods, etc., related to each of the deformability described above can be modified as appropriate without departing from the scope of the objectives of the present invention. [Explanation of Symbols]

[0158] 11 Workpiece 11a Surface (first side) 11b Back side (2nd side) 2. Grinding device 4 base 4a aperture 6. Transport Unit (Transport Mechanism) 8a,8b Cassette installation area 10a, 10b Cassette 12. Alignment mechanism 14. Transport Unit (Transport Mechanism, Loading Arm) 16 Turntables 16a Base 16b Cover 16c hole 18. Chuck tables (first chuck table, second chuck table) 18a Holding surface 20 Frame 20a top surface 20b recess 22 Porous plate 22a Top side 24 rotation axes 26 spindles 28a,28b Support structure 30a, 30b Mobile unit (mobile mechanism) 32 Guide Rails 34 Mobile Plate 36 Ball screw 38 Pulse motor 40a Grinding Unit (Coarse Grinding Unit) 40b Grinding Unit (Finishing Grinding Unit) 42 Housing 44a spindle 44b Spindle 46a motor 46b Motor 48a Wheel Mount 48b Wheel Mount 50a Grinding Wheel (Coarse Grinding Wheel) 50b Grinding Wheel (Finishing Grinding Wheel) 52a Wheel base 52b Wheel base 54a Grinding Wheel 54b Grinding Wheel 56a Ammeter (Second load measuring instrument, second measuring unit) 56b Ammeter (First load measuring instrument, first measuring unit) 60 Controllers (control units, control units, control devices) 62 Processing Unit 64 Storage device 66 Coordination Headquarters 68 First threshold memory unit 70 Second threshold memory unit 72. Transport Unit (Transport Mechanism, Unloading Arm) 74. Cleaning Unit (Cleaning Mechanism, Cleaning Device) 80a Thickness measuring instrument (2nd measuring unit) 80b Thickness measuring instrument (first measuring unit) 82 Shaft section 84 Arm 90 Adjustment mechanism 92 Chuck Table Support Plate 94 bearings 96 Height adjustment mechanism 98 Drive Unit 98a motor 98b reducer 100 shaft 102 Cylinder part 104 screws 106 Nuts 110 Motor 112 Rotation axis 114 belt 116 Flow channels 118 Support mechanism 120 Load detector (load measuring device, measuring unit)

Claims

1. A grinding device for grinding a workpiece, A plurality of chuck tables, each having a holding surface for holding the workpiece, and rotatable around a rotation axis intersecting the holding surfaces, A first grinding unit having a first spindle with a first grinding wheel mounted at its tip for rough grinding the workpiece, A second grinding unit having a second spindle with a second grinding wheel mounted at its tip for finish grinding the workpiece, A first adjustment mechanism for adjusting the first angle between the rotation axis of the chuck table that holds the workpiece during rough grinding and the first spindle, A first measuring unit measures the first state when the workpiece, held on a chuck table that holds the workpiece during finish grinding, is being ground by the second grinding unit, The system comprises at least the first adjustment mechanism, the first measuring unit, and a controller for controlling the first adjustment mechanism, Grinding apparatus, the controller includes an adjustment command unit that adjusts the first angle by the first adjustment mechanism based on the first state measured by the first measuring unit.

2. The first measuring unit is a first thickness measuring instrument that measures the thickness of a workpiece held by a chuck table that holds the workpiece during finish grinding. The grinding apparatus according to claim 1, wherein the adjustment command unit adjusts the first angle using the first adjustment mechanism based on the thickness of two or more points on the workpiece measured by the first thickness measuring instrument.

3. The first measuring unit is a first load measuring instrument that measures the load applied to the chuck table or the second spindle that holds the workpiece during finish grinding. The grinding apparatus according to claim 1, wherein the adjustment command unit adjusts the first angle using the first adjustment mechanism based on the load measured by the first load measuring instrument.

4. The controller further includes a first threshold storage unit that stores a first threshold value which is the permissible upper limit of the load. The grinding apparatus according to claim 3, wherein the adjustment command unit increases the first angle by the first adjustment mechanism when the load measured by the first load measuring instrument is greater than the first threshold value.

5. The controller further includes a second threshold storage unit that stores a second threshold value which is the allowable lower limit of the load. The grinding apparatus according to claim 3, wherein the adjustment command unit reduces the first angle by the first adjustment mechanism when the load measured by the first load measuring instrument is smaller than the second threshold value.

6. A second adjustment mechanism for adjusting the second angle between the rotation axis of the chuck table that holds the workpiece during finish grinding and the second spindle, The system further comprises a second measuring unit for measuring a second state when grinding a workpiece held on a chuck table that holds the workpiece during finish grinding, using the second grinding unit. The grinding apparatus according to any one of claims 1 to 5, wherein the adjustment command unit operates one or both of the first adjustment mechanism and the second adjustment mechanism based on one or both of the first state measured by the first measuring unit and the second state measured by the second measuring unit to adjust one or both of the first angle and the second angle.

7. The grinding apparatus according to claim 6, wherein the second measuring unit is a second thickness measuring instrument for measuring the thickness of a workpiece held by a chuck table that holds the workpiece during rough grinding.

8. The grinding apparatus according to claim 6, wherein the second measuring unit is a second load measuring instrument that measures the load applied to the chuck table or the first spindle that holds the workpiece during rough grinding.

9. A grinding device for grinding a workpiece, A chuck table having a holding surface for holding the workpiece and rotatable about a rotation axis intersecting the holding surface, A first grinding unit having a first spindle with a first grinding wheel mounted at its tip for rough grinding the workpiece, A second grinding unit having a second spindle with a second grinding wheel mounted at its tip for finish grinding the workpiece, An adjustment mechanism for adjusting the angle between the rotating shaft and the first spindle, A measuring unit for measuring the state of the workpiece held on the chuck table when it is being ground by the second grinding unit, The system comprises at least the adjustment mechanism, the measuring unit, and a controller for controlling the adjustment mechanism, The controller includes an adjustment command unit that adjusts the angle by an adjustment mechanism based on the state measured by the measuring unit, in a grinding apparatus.

10. The measuring unit is a thickness measuring instrument that measures the thickness of the workpiece held by the chuck table. The grinding apparatus according to claim 9, wherein the adjustment command unit adjusts the angle using the adjustment mechanism based on the thickness of the workpiece measured by the thickness measuring instrument at two or more points.

11. The measuring unit is a load measuring instrument that measures the load applied to the chuck table or the second spindle. The grinding apparatus according to claim 9, wherein the adjustment command unit adjusts the angle using the adjustment mechanism based on the load measured by the load measuring instrument.

12. The controller further includes a first threshold storage unit that stores a first threshold value which is the permissible upper limit of the load. The grinding apparatus according to claim 11, wherein the adjustment command unit increases the angle by the adjustment mechanism when the load measured by the measurement unit is greater than the first threshold value.

13. The controller further includes a second threshold value storage unit that stores a second threshold value which is the allowable lower limit of the load. The grinding apparatus according to claim 11, wherein the adjustment command unit reduces the angle by the adjustment mechanism when the load measured by the measurement unit is less than the second threshold value.

14. A method for adjusting grinding conditions, which is used to adjust the conditions for grinding a workpiece. A first grinding step involves using a first grinding unit having a first spindle with a first grinding wheel attached to its tip to roughly grind the first workpiece held by a rotating chuck table, A second grinding step is performed using a second grinding unit having a second spindle with a second grinding wheel attached to its tip for finish grinding the workpiece, thereby finishing grinding the first workpiece held by the rotating chuck table or another rotating chuck table. A method for adjusting grinding conditions, comprising: an angle adjustment step, which adjusts the angle between the rotation axis of the chuck table that holds the second workpiece and the first spindle when rough grinding a second workpiece, which is different from the first workpiece, based on the conditions measured in the second grinding step.

15. The method for adjusting grinding conditions according to claim 14, wherein the state measured in the second grinding step is the thickness of two or more points of the workpiece at the end of the second grinding step, the load applied to the second spindle in the second grinding step, or the load applied to the chuck table holding the first workpiece in the second grinding step.

16. A method for grinding a workpiece using the method for adjusting grinding conditions described in claim 14 or claim 15, A method for grinding a workpiece, further comprising: a third grinding step, after the angle adjustment step, using the first grinding unit to roughly grind the second workpiece, which is the target of the angle adjustment step and is held by a rotating chuck table.

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