Grinding device and grinding method

Abstract

To appropriately correct the thickness unevenness of a workpiece caused by a difference between a shape formed on an upper surface of the workpiece by grinding and a shape formed on an upper surface of a chuck table by self-grinding.SOLUTION: A grinding method using a grinding device which comprises a chuck table and a grinding mechanism provided with a rotating grinding wheel, and moves the grinding wheel and the chuck table relatively to each other along a grinding surface, includes: a holding surface grinding step of performing self-grinding of the chuck table; a Z-axis movement setting step of setting a value relating to movement of the chuck table, or an inclination angle setting step of setting either an inclination angle of the grinding wheel or the chuck table; and a workpiece grinding step of grinding the workpiece under the settings made in the inclination angle setting step.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a grinding device and a grinding method for grinding a workpiece by relatively moving a chuck table that holds the workpiece and a grinding unit that has a grinding wheel that grinds the workpiece while rotating a grinding stone. [Background technology]

[0002] Semiconductor chips mounted on electronic devices such as mobile phones are manufactured, for example, by the following procedure: First, a plurality of planned dividing lines (streets) are set in a grid pattern on the surface of a wafer formed from a semiconductor such as silicon, devices are formed in each of the rectangular areas defined by the plurality of streets, and then the wafer is cut along each street.

[0003] In recent years, there has been a demand for thinner wafers in order to reduce the size and weight of semiconductor chips, etc. One technique for thinning wafers is a method called creep feed grinding, as described in Patent Document 1 below.

[0004] Creep feed grinding is performed, for example, as follows: First, the wafer to be ground is held on a chuck table. The chuck table is a base for holding the wafer, and the front side of the wafer is sucked and held on its upper surface. In this state, the wafer is placed above the chuck table with the back side facing up.

[0005] In the initial state before the grinding process begins, a chuck table is positioned away from the grinding wheel. The grinding wheel is a disk-shaped tool with a grinding stone on its underside, and is attached to the lower end of a cylindrical spindle whose axis is aligned vertically. When the spindle rotates around its axis, the disk-shaped grinding wheel attached to the spindle rotates integrally with the spindle.

[0006] In the initial state, the positions of the chuck table and the grinding wheel do not overlap in a plan view, and the lower end of the grinding stone attached to the lower surface of the grinding wheel is positioned slightly lower than the upper end of the wafer held on the chuck table.

[0007] From this state, when the chuck table is moved horizontally relative to the grinding wheel while the grinding wheel is being rotated, the upper surface of the wafer comes into contact with the grinding stone and the wafer is ground.

[0008] However, when performing such creep feed grinding, even if the holding surface of the chuck table is parallel to the rotational surface of the grinding wheel and the chuck table is moved in a direction parallel to the rotational surface, the upper surface of the wafer after grinding may not be completely flat due to wear of the grinding stone during grinding, etc.

[0009] In order to correct this unevenness in wafer thickness that occurs during grinding, it is effective to perform self-grinding prior to grinding the wafer. In self-grinding, the holding surface of the chuck table on which the wafer is held is ground by creep feed grinding similar to that described above. This allows the holding surface of the chuck table to be formed in advance with a shape similar to the shape that will be formed on the upper surface of the wafer during creep feed grinding.

[0010] After the holding surface of the chuck table is ground by self-grinding, a wafer is held on the holding surface of the chuck table and grinding is performed.If the shape of the top surface of the chuck table and the top surface of the wafer after grinding are roughly the same, it can be expected that the thickness of the wafer will be roughly uniform.

[0011] However, even if the wafer grinding and the preceding self-grinding are performed in the same way, the wafer thickness will not necessarily be uniform. This is because if the materials of the chuck table and the wafer (the workpiece) are different, the degree of wear of the grinding stone will differ even if the grinding is performed in the same way, and as a result, the shape formed on the top surface of the wafer by grinding will differ from the shape of the holding surface of the chuck table ground by self-grinding. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2022-142022 Summary of the Invention [Problem to be solved by the invention]

[0013] An object of the present invention is to provide a grinding device and a grinding method that can effectively correct uneven thickness of a workpiece caused by the difference between the shape formed on the top surface of the workpiece by grinding and the shape formed on the top surface of the chuck table by self-grinding. [Means for solving the problem]

[0014] According to one aspect of the present invention, there is provided a grinding mechanism including a chuck table having a holding surface for holding a workpiece, a grinding mechanism equipped with a spindle attached with a grinding wheel having a grinding stone fixed thereto and rotating together with the grinding wheel, a Y-axis movement mechanism for relatively moving the grinding wheel and the chuck table in a direction along the grinding surface formed by the rotating grinding stone, a memory unit for storing data, a Z-axis movement mechanism for relatively moving the grinding wheel and the chuck table along the Z-axis by the Y-axis movement mechanism, with the Y-axis being a direction parallel to the direction in which the grinding mechanism and the chuck table move relatively, the Z-axis being a direction perpendicular to the Y-axis and along the rotation axis of the grinding stone, and the X-axis being a direction perpendicular to the Y-axis and Z-axis, or at least one of a tilt angle adjustment mechanism for adjusting the tilt angle of the grinding wheel or the chuck table about the X-axis, and a controller for controlling the Z-axis movement mechanism or the tilt angle adjustment mechanism, wherein the memory unit stores data for storing data for the grinding mechanism when no workpiece is held on the chuck table. a grinding apparatus configured to: move the chuck table and the grinding wheel relatively along the Y-axis while rotating the grinding wheel, perform self-grinding to grind the holding surface of the chuck table; hold a workpiece to be adjusted on the holding surface of the chuck table; move the chuck table and the grinding wheel relatively along the Y-axis while rotating the grinding wheel to grind the workpiece to be adjusted; and then store data related to the measured thickness of the workpiece to be adjusted; when controlling the Z-axis movement mechanism, the controller is configured to adjust a value related to the relative movement of the grinding wheel and the chuck table along the Z-axis based on the data related to the thickness of the workpiece to be adjusted stored in the memory; and when controlling the tilt angle adjustment mechanism, to adjust at least one of the tilt angle of the grinding wheel or the tilt angle of the chuck table based on the data related to the thickness of the workpiece to be adjusted stored in the memory.

[0015] Preferably, the Z-axis movement mechanism is configured to adjust a value z relating to the relative movement of the grinding wheel and the chuck table along the Z-axis based on the thickness distribution along the X-axis of the workpiece for adjustment stored in the memory unit.

[0016] Preferably, the tilt angle adjustment mechanism is configured to adjust the tilt angle θ of the chuck table about the X-axis based on the thickness distribution along the Y-axis of the workpiece for adjustment stored in the memory unit.

[0017] Preferably, the tilt angle adjustment mechanism is configured to adjust at least one of the tilt angle α of the chuck table about the Y axis and the tilt angle β of the grinding wheel about the Y axis, based on the thickness distribution along the X axis of the workpiece to be adjusted stored in the memory unit.

[0018] According to another aspect of the present invention, a grinding device is used that includes a chuck table having a holding surface for holding a workpiece, a grinding mechanism having a spindle to which a grinding wheel having a grinding stone is attached and which rotates together with the grinding wheel, and a Y-axis movement mechanism that moves the grinding wheel and the chuck table relatively along the grinding surface formed by the rotating grinding stone, and the method includes a holding surface grinding step in which, without a workpiece being held on the chuck table, the chuck table and the grinding stone are moved relatively along the Y-axis while the grinding stone is rotated to perform self-grinding to grind the holding surface of the chuck table, a workpiece holding step for holding a workpiece to be adjusted on the holding surface of the chuck table, a workpiece grinding step for grinding the workpiece to be adjusted by moving the chuck table and the grinding stone relatively along the Y-axis while rotating the grinding stone, and a thickness measurement step for measuring thicknesses at a plurality of positions on the workpiece to be adjusted that has undergone the workpiece grinding step. a Z-axis movement setting step of setting a value related to the relative movement of the grinding wheel and the chuck table along the Z-axis based on the thickness distribution of the workpiece for adjustment measured in the thickness measurement step, where a direction parallel to the direction in which the grinding mechanism and the chuck table move relatively is defined as the Y-axis, a direction perpendicular to the Y-axis and along the rotation axis of the grinding wheel is defined as the Z-axis, and a direction perpendicular to the Y-axis and Z-axis is defined as the X-axis; or a tilt angle setting step of setting at least one of the tilt angle of the grinding wheel and the tilt angle of the chuck table; a workpiece holding step of holding the workpiece on the holding surface of the chuck table; and a workpiece grinding step of grinding the workpiece by moving the chuck table and the grinding wheel relatively while rotating the grinding wheel based on the settings made in the Z-axis movement setting step or the tilt angle setting step.

[0019] Preferably, in the Z-axis movement setting step, a value z relating to the relative movement along the Z-axis between the grinding wheel and the chuck table is set based on the thickness distribution along the X-axis of the adjustment workpiece.

[0020] Preferably, in the tilt angle setting step, the tilt angle θ of the chuck table about the X axis is adjusted based on the thickness distribution along the Y axis of the workpiece for adjustment.

[0021] Preferably, in the inclination angle setting step, at least one of the inclination angle α of the chuck table about the Y axis and the inclination angle β of the grinding wheel about the Y axis is adjusted based on the thickness distribution along the X axis of the workpiece for adjustment.

[0022] Preferably, the adjustment workpiece is made of the same material as the workpiece. [Effects of the Invention]

[0023] According to one aspect of the grinding device and grinding method of the present invention, the shape of the curved surface formed on the holding surface of the chuck table by self-grinding is made to approximate the shape of the curved surface formed on the upper surface of the workpiece by subsequent grinding, thereby making it possible to grind the workpiece to a uniform thickness.

[0024] In other words, assuming that the chuck table is self-grinding and that thickness variations may still occur in the workpiece, by adjusting at least some of the values ​​related to the relative movement between the chuck table and grinding wheel along the Z axis, the chuck table inclination angle, and the grinding wheel inclination angle, it is possible to align the shapes of the curved surfaces formed on the chuck table and workpiece by grinding, thereby obtaining a workpiece with a more uniform thickness. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a perspective view schematically showing an example of the configuration of a grinding device. [Figure 2] FIG. 2 is a side view of the grinding apparatus of FIG. [Figure 3] FIG. 3 is a flowchart showing an example of the procedure of the grinding method. [Figure 4]Figure 4(A) is a graph showing a schematic example of the thickness distribution in the Y-axis direction of an adjustment workpiece after creep feed grinding, and Figure 4(B) is a graph showing a schematic example of the thickness distribution in the X-axis direction of an adjustment workpiece after creep feed grinding. [Figure 5] Figure 5(A) is a diagram showing a schematic representation of the shape formed on the upper surface of the workpiece by grinding, as a virtual oblique cylinder with a relatively large inclination and the corresponding curvature of the curved surface, and Figure 5(B) is a diagram showing a schematic representation of the shape formed on the upper surface of the workpiece by grinding, as a virtual oblique cylinder with a relatively small inclination and the corresponding curvature of the curved surface. [Figure 6] FIG. 6 is a schematic diagram illustrating values ​​related to the movement of the grinding wheel along the Z axis and the tilt angles of the chuck table and grinding wheel about the X axis. [Figure 7] FIG. 7 is a schematic diagram illustrating the tilt angles of the chuck table and the grinding wheel about the Y axis. [Figure 8] FIG. 8(A) is a graph showing a schematic example of the thickness distribution in the Y-axis direction of a workpiece after creep feed grinding, and FIG. 8(B) is a graph showing a schematic example of the thickness distribution in the X-axis direction of a workpiece after creep feed grinding. [Figure 9] FIG. 9 is a flowchart showing another example of the procedure of the grinding method. DETAILED DESCRIPTION OF THE INVENTION

[0026] An embodiment of the present invention will be described with reference to the accompanying drawings. First, a grinding device used in this embodiment will be described. Figures 1 and 2 are a perspective view and a side view, respectively, that schematically show an example of the configuration of the grinding device.

[0027] As shown in FIG. 1, the grinding device 2 includes a horizontal movement mechanism 4 serving as a Y-axis movement mechanism that supports a chuck table 16 and moves it horizontally, and a support structure 18 that supports a grinding wheel 40.

[0028] The support structure 18 is equipped with a grinding mechanism 32 that rotates the grinding wheel 40 and grinds the object to be ground. The Y-axis movement mechanism is a mechanism that moves the grinding wheel 40 and the chuck table 16 relatively in a direction along the grinding surface (the surface formed by the rotation of the grinding stone 40b attached to the grinding wheel 40).

[0029] In this embodiment, the horizontal movement mechanism 4, which is a Y-axis movement mechanism, moves the chuck table 16 in the horizontal direction relative to the support structure 18 that supports the grinding wheel 40, thereby performing relative movement between the grinding wheel 40 and the chuck table 16 along the grinding surface. The definitions of the coordinate axes (X-axis, Y-axis, and Z-axis) in three-dimensional space will be described later.

[0030] The horizontal movement mechanism 4 is provided with two horizontal guide rails 6 extending parallel to each other in the horizontal direction. A horizontal movement table 8 is supported on the horizontal guide rails 6 so as to be slidable along the longitudinal direction of the horizontal guide rails 6.

[0031] In this specification, expressions such as "along the horizontal direction" and "along the Y-axis" do not only mean that the direction exactly coincides with the horizontal direction or the Y-axis direction, but also include cases where the direction is roughly close to those directions or where it is acceptable to recognize it as such.

[0032] A horizontal ball screw 10 is disposed between the two horizontal guide rails 6 along the direction in which the horizontal guide rails 6 extend. A nut portion (not shown) is provided on the rear surface side (lower surface side) of the horizontal movement table 8, and the horizontal ball screw 10 passes through the nut portion.

[0033] A horizontal movement motor 12, which is a pulse motor, is connected to one end of the horizontal ball screw 10. When the horizontal movement motor 12 is driven to rotate the horizontal ball screw 10 around its axis, the horizontal movement table 8 slides along the horizontal guide rail 6.

[0034] A support base 14 is attached to the front surface (top surface) of the horizontally moving table 8, and a chuck table 16 having a substantially circular shape in a plan view is disposed on top of the support base 14. The upper surface of the chuck table 16 forms a holding surface 16a that holds the workpiece 11.

[0035] The workpiece 11 is, for example, a plate-like object (wafer) made of a semiconductor material such as silicon, and in the example shown in FIG. 1, has a thin disk-like shape.

[0036] A columnar support structure 18 is provided adjacent to the horizontal movement mechanism 4. A lifting table 24 is provided on the front surface of the support structure 18 (the surface on the near side in FIG. 1) via a lifting mechanism 20 serving as a Z-axis movement mechanism.

[0037] The Z-axis movement mechanism is a mechanism that moves the grinding wheel 40 and the chuck table 16 relatively along the Z axis. In this embodiment, the lifting mechanism 20, which is the Z-axis movement mechanism, supports the grinding wheel 40 and moves it along the Z axis relative to the chuck table 16, thereby performing relative movement of the grinding wheel 40 and the chuck table 16 along the Z axis. The definitions of the coordinate axes will be described later.

[0038] The lifting mechanism 20 is attached to the front surface of the support structure 18 and includes two lifting guide rails 22 that extend parallel to each other along the Z axis (vertical direction). A lifting table 24 is supported on the lifting guide rails 22 so as to be slidable along the two lifting guide rails 22.

[0039] An elevator ball screw 26 is disposed between the two elevator guide rails 22 along the direction in which the elevator guide rails 22 extend. A nut portion (not shown) is provided on the rear side (rear side) of the elevator table 24, and the elevator ball screw 26 passes through the nut portion.

[0040] A lift motor 28, which is a pulse motor, is connected to one end of the lift ball screw 26, and when the lift motor 28 is driven to rotate the lift ball screw 26 around its axis, the lift table 24 slides up and down along the lift guide rail 22.

[0041] The rear side of the lift table 24 is attached to the lift mechanism 20 in this manner, while the front side supports the grinding mechanism 32 .

[0042] The grinding mechanism 32 includes a spindle housing 34 and a spindle 36, which is a rotating body housed in the spindle housing 34. The spindle 36, which is a cylindrical member, is supported by the spindle housing 34 so as to be rotatable about an axis provided along the vertical direction, and constitutes the rotation axis of the grinding wheel 40.

[0043] A disk-shaped wheel mount 38 is fixed to the tip of the lower end of the spindle 36, and a disk-shaped grinding wheel 40 having approximately the same diameter as the wheel mount 38 is attached to the underside of the wheel mount 38. The grinding wheel 40 has an annular wheel base 40a made of stainless steel or the like, and a plurality of grinding stones 40b are fixed around the underside of the wheel base 40a.

[0044] A rotation drive source (not shown) such as a motor is connected to the upper end of the spindle 36, thereby causing the spindle 36 to rotate.

[0045] When the spindle 36 rotates, the grinding wheel 40 attached to the spindle 36 rotates integrally with the spindle 36, and the circular path traced by the lower end of the grinding stone 40b as it rotates forms a grinding surface that comes into contact with the workpiece 11 and grinds it.

[0046] The grinding device 2 has the above-described configuration, and in particular, in the case of the grinding device 2 of this embodiment, the angle of the chuck table 16 and the angle of the grinding wheel 40 can be adjusted by the tilt angle adjustment mechanisms 44, 46, respectively.

[0047] In the present embodiment, the directions of three axes in three-dimensional space are defined as follows for convenience. Y-axis: A direction parallel to the direction in which the grinding wheel 40 and the chuck table 16 move relatively by the Y-axis movement mechanism (a direction along the longitudinal direction of the horizontal guide rail 6; in this embodiment, a horizontal direction). Z-axis: A direction perpendicular to the Y-axis and along the rotation axis of the grinding wheel 40b (a direction along the rotation axis of the spindle 36 and the longitudinal direction of the lift guide rail 22; in this embodiment, a vertical direction) X-axis: Orthogonal to the Y-axis and Z-axis The chuck table 16 is configured to tilt along the YZ plane (around the X axis) around an axis along the X axis direction by the tilt angle adjustment mechanism 44. In addition to this, the tilt angle adjustment mechanism 44 may also be configured to tilt the chuck table 16 along the XZ plane (around the Y axis) around an axis along the Y axis.

[0048] Any suitable mechanism can be used in the tilt angle adjustment mechanism 44 as a mechanism for tilting the chuck table 16. For example, a mechanism for adjusting the distance between the chuck table 16 and the horizontally moving table 8 can be provided at multiple locations between the chuck table 16 and the horizontally moving table 8, and the angle of the chuck table 16 relative to the horizontally moving table 8 can be adjusted by changing the distance at these locations.

[0049] The grinding wheel 40 is tilted along the YZ plane around an axis along the X-axis direction together with the spindle 36 by the tilt angle adjustment mechanism 46. In addition, the tilt angle adjustment mechanism 46 may be configured to tilt the grinding wheel 40 along the XZ plane around an axis along the Y-axis direction.

[0050] Any suitable mechanism can be used as the mechanism for tilting the grinding wheel 40 and the spindle 36 with the tilt angle adjustment mechanism 46. For example, a mechanism for adjusting the distance between the spindle housing 34 and the spindle housing 34 can be provided at multiple parts of the spindle housing 34 that support the spindle housing 34, and the angle of the spindle 36 relative to the spindle housing 34 can be adjusted by changing the distance at these installation points.

[0051] A controller 42 that controls the operation of each component of the grinding apparatus 2 is connected to the grinding apparatus 2. The controller 42 is configured, for example, by a computer, and includes a calculation unit 42d that performs various calculations necessary for the operation of the grinding apparatus 2, and a storage unit 42e that stores various information (data, programs, etc.) used for the operation of the grinding apparatus 2. The calculation unit 42d includes a processor such as a CPU (Central Processing Unit). The storage unit 42e includes memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). In addition, the controller 42 includes a rotation control unit 42a, a position control unit 42b, and a tilt control unit 42c as units that control the operation of each component of the grinding apparatus 2.

[0052] The rotation control unit 42a controls the operation of a motor (not shown) that drives the rotation of the spindle 36. The position control unit 42b controls the horizontal movement table 8 and the lifting table 24 by operating the horizontal movement motor 12 and the lifting motor 28. That is, the position control unit 42b controls the Y-axis movement mechanism (horizontal movement mechanism) 4 and the Z-axis movement mechanism (lifting mechanism) 20. The tilt control unit 42c adjusts the tilt of the chuck table 16 and the grinding wheel 40 by controlling the tilt angle adjustment mechanisms 44, 46.

[0053] Furthermore, in the grinding apparatus 2 of this embodiment, a thickness measurement unit 48 is connected to the controller 42. The thickness measurement unit 48 is, for example, a contact-type measuring instrument, and includes a first measuring instrument 48a that measures the height position of the upper surfaces 11a, 17a of the articles (workpiece 11, workpiece for adjustment 17) held on the holding surface 16a of the chuck table 16, and a second measuring instrument 48b that measures the height position of the holding surface 16a of the chuck table 16. The thickness of each location of the article held on the chuck table 16 can be measured from the difference between the measurement value of the first measuring instrument 48a and the measurement value of the second measuring instrument 48b.

[0054] In particular, in this embodiment, the thickness measuring unit 48 is capable of measuring the thicknesses of the workpiece 11 and the adjustment workpiece 17 at a plurality of positions after grinding.

[0055] The mechanism for measuring the thickness by the thickness measurement unit 48 is not limited to a mechanism using such a contact-type measuring device, and any mechanism may be used as long as it can measure the thickness at each position of the object to be measured with sufficient accuracy. For example, a measuring device that measures the thickness using a non-contact distance measuring device using light may be used.

[0056] Furthermore, the calculation unit 42d calculates, using the procedure described below, at least one of a set value for the movement of the grinding wheel 40 along the Z axis in creep feed grinding, a set value for the tilt angle of the chuck table 16 about the X axis in creep feed grinding, and a set value for the tilt angle of the grinding wheel 40 about the X axis.

[0057] In addition, the calculation unit 42d may be configured to calculate at least one of a set value of the tilt angle of the chuck table 16 about the Y axis and a set value of the tilt angle of the grinding wheel 40 about the Y axis. These set values ​​will be described in detail later.

[0058] The memory unit 42e stores the above-mentioned set values ​​calculated by the calculation unit 42d. In addition, the memory unit 42e stores data on the thickness of the article (workpiece 11 or workpiece for adjustment 17) measured by the thickness measurement unit 48, for example (measurement values ​​measured by the first and second measuring instruments 48a and 48b at multiple positions on the workpiece, thicknesses at various positions calculated based on these values, thickness distributions in the Y-axis direction and the X-axis direction, etc.).

[0059] An input / output unit 42f is connected to the controller 42. The input / output unit 42f is a user interface such as a keyboard or a monitor display, and an operator who operates the grinding device 2 can operate the grinding device 2 via the controller 42 by inputting operations to the input / output unit 42f.

[0060] The grinding procedure performed by the grinding device 2 will be described with reference to the flowchart of FIG.

[0061] First, self-grinding is performed (holding surface grinding step; step S10) without holding the workpiece (wafer) 11 on the chuck table 16. In this self-grinding, the holding surface 16a of the chuck table 16 is ground by creep feed grinding.

[0062] At this time, the setting values ​​for the tilt angles of the chuck table 16 and grinding wheel 40, and the movement of the grinding wheel 40 along the Z axis are set to initial values. The initial values ​​may all be set to zero (the chuck table 16 is horizontal, the axes of the grinding wheel 40 and spindle 36 are vertical, and the grinding wheel 40 does not move up or down from its initial position), for example, but values ​​other than zero may also be set for the tilt angle, position, and movement.

[0063] Self-grinding is performed as follows. First, the chuck table 16 is positioned so that it does not overlap the grinding wheel 40 in a plan view. The height of the grinding wheel 40 is adjusted so that the bottom end of the grinding stone 40b is slightly lower than the holding surface 16a at the top end of the chuck table 16. The positions of the chuck table 16 and the grinding wheel 40 can be adjusted by operating the horizontal movement motor 12 or the lift motor 28 via the position control section 42b of the controller 42.

[0064] From this state, a motor (not shown) is driven via the rotation control unit 42a, causing the grinding wheel 40 to rotate together with the spindle 36. At the same time, the horizontal movement motor 12 is driven via the position control unit 42b, causing the chuck table 16 to approach the grinding wheel 40 along the Y axis. When the chuck table 16 comes into contact with the grinding wheel 40, grinding begins. Grinding continues until the entire holding surface 16a of the chuck table 16 is ground from one end to the other end in the Y axis direction.

[0065] After step S10 is completed, the workpiece for adjustment 17 is held on the holding surface 16a that has been self-ground (workpiece for adjustment holding step; step S20). The workpiece for adjustment 17 is an article (e.g., a silicon crystal wafer) made of the same material as the workpiece 11. Furthermore, it is desirable that the workpiece for adjustment 17 be set to have the same shape and dimensions as the workpiece 11 that is to be ground.

[0066] Creep feed grinding is performed on the adjustment workpiece 17 held on the holding surface 16a (adjustment workpiece grinding step; step S30). At this time, the setting values ​​for the tilt angle of the chuck table 16, the tilt angle of the grinding wheel 40, and the movement of the grinding wheel 40 along the Z-axis direction are set to the same initial values ​​as in step S10.

[0067] In step S30, first, the chuck table 16 is positioned so that it does not overlap the grinding wheel 40 in a plan view. The height of the grinding wheel 40 is adjusted so that the lower end of the grinding stone 40b is slightly lower than the upper surface 17a of the workpiece for adjustment 17. As the grinding wheel 40 rotates, the chuck table 16 moves along the Y-axis, and the entire upper surface 17a of the workpiece for adjustment 17 is ground in the Y-axis direction.

[0068] The thickness of each point of the ground adjustment workpiece 17 in plan view is measured by the thickness measurement unit 48 (thickness measurement step; step S40). In this step, for example, the thickness of the intermediate portion in the X-axis direction is measured at a plurality of positions throughout the Y-axis direction (measurement of thickness distribution along the Y-axis direction). Also, the thickness of the intermediate portion in the Y-axis direction is measured at a plurality of positions throughout the X-axis direction (measurement of thickness distribution along the X-axis direction).

[0069] An example of the thickness distribution measured in step S40 is shown in Figures 4(A) and 4(B). In the example shown here, in the Y-axis direction, as shown in Figure 4(A), the distribution is thicker toward the front (closer to the grinding wheel 40 in the initial state before grinding starts) in the movement direction of the chuck table 16 and becomes thinner toward the rear. In the X-axis direction, as shown in Figure 4(B), the distribution is thicker in the middle and becomes thinner toward both ends.

[0070] The unevenness in thickness that occurs with creep feed grinding will now be explained.

[0071] First, we will explain the shape of the surface formed on the top surface of the workpiece by creep feed grinding. When creep feed grinding is performed, even if the holding surface 16a of the chuck table 16 is parallel to the rotational plane of the grinding wheel 40 and the chuck table 16 is moved in a direction parallel to the rotational plane of the grinding wheel 40, the top surface of the workpiece after grinding will not be completely flat but will have a slightly concave curved surface. This is because the grinding wheel 40b wears out during grinding.

[0072] If we consider a situation in which the spindle 36 is supported at its original height and the grinding wheel 40 rotates horizontally around a vertical axis of rotation to perform grinding, the lower end of the grinding stone 40b attached to its underside will wear down as grinding progresses, causing it to rise little by little.

[0073] Therefore, during grinding, the grinding surface formed by the lower end of grinding wheel 40b rises little by little while tracing a circular trajectory due to rotation, and the workpiece moves toward it in the Y-axis direction, grinding its upper surface. As a result, a curved surface roughly corresponding to a part of the side surface of an oblique cylinder is formed on the upper surface of the workpiece.

[0074] In order to make the thickness of the wafer (workpiece 11, adjustment workpiece 17) that is the object to be ground as uniform as possible, assuming that a curved surface will be formed during grinding, it is effective to perform self-grinding prior to grinding the wafer. In self-grinding, the holding surface 16a of the chuck table 16 on which the wafer is held is ground by creep feed grinding, similar to the surface where the wafer is ground. This allows the holding surface 16a of the chuck table 16 to be formed in advance with a shape similar to the shape that will be formed on the top surface of the wafer during creep feed grinding.

[0075] After forming an oblique cylindrical side shape on the holding surface 16a of the chuck table 16 by self-grinding, if a wafer is held on the holding surface 16a of the chuck table 16 and creep feed grinding is performed, and a similar oblique cylindrical side shape is formed on the top surface of the wafer, the shapes of the top and bottom surfaces of the wafer will be roughly the same, and it can be expected that the thickness of the wafer will be approximately uniform.

[0076] However, in reality, even if the creep feed grinding of the wafer and the preceding self-grinding are performed in the same manner, the wafer thickness will not necessarily be uniform because the materials of the chuck table 16 and the wafer, which is the workpiece 11, are different.

[0077] For example, if the chuck table 16 is made of a material that is harder to grind than the silicon crystals that make up the wafers, the degree of wear of the grinding wheel 40b due to self-grinding is greater than the degree of wear of the grinding wheel 40b due to wafer grinding. Therefore, the difference in height between the bottom end of the grinding wheel 40b at the start and end of grinding is greater in self-grinding than in wafer grinding.

[0078] In other words, the inclination in the Y-axis direction of the curved surface formed on the holding surface 16a of the chuck table 16 by self-grinding is greater than the inclination in the Y-axis direction of the curved surface formed on the top surface of the wafer by wafer grinding (note that if the material of the chuck table is more easily ground than the material of the wafer, the relationship between the magnitude of the inclination will be reversed.) This difference in inclination will directly appear as unevenness in the thickness of the wafer when creep feed grinding is performed while the wafer is held on the holding surface 16a of the self-grinded chuck table 16.

[0079] 4(A) is due to the difference in the degree of wear of the grinding wheel 40b caused by the difference in the materials of the chuck table 16 and the adjustment workpiece 17. If the material of the workpiece to be ground is difficult to grind, the degree of wear of the grinding wheel 40b during grinding increases, and therefore the amount of rise of the grinding surface of the grinding wheel 40b from the start to the end of grinding increases.

[0080] If the material of the chuck table 16 is more difficult to grind than the workpiece to be adjusted 17, the inclination in the Y-axis direction of the grinding surface formed on the holding surface 16a of the chuck table 16 will be greater. When grinding the workpiece to be adjusted 17, which is easier to grind than the chuck table 16, the degree of wear of the grinding wheel 40b is relatively small, so the amount of rise in the grinding surface of the grinding wheel 40b from the start to the end of grinding is small. Therefore, the inclination in the Y-axis direction of the grinding surface formed on the upper surface 17a of the workpiece to be adjusted 17 will be smaller.

[0081] The lower surface of the workpiece for adjustment 17 is held by the holding surface 16a of the chuck table 16, so the shape of the lower surface of the workpiece for adjustment 17 roughly follows the shape of the holding surface 16a. On the other hand, the shape of the upper surface 17a is formed by grinding as described above, so that the thickness of the workpiece for adjustment 17 has a deviation along the Y axis as shown in Figure 4(A).

[0082] Furthermore, during grinding, in addition to the tilt in the Y-axis direction, a curved shape is formed on the top surface of the workpiece (wafer or chuck table) in the X-axis direction as well. This is because the shape formed on the top surface of the workpiece by grinding roughly corresponds to part of the side surface of an oblique cylinder, as described above.

[0083] If the inclinations of the axes of the oblique cylinders corresponding to the curved surfaces formed on both the holding surface 16a of the chuck table 16 and the upper surface of the wafer are different from each other, the difference in the shapes of the side surfaces of the corresponding oblique cylinders may cause uneven thickness in the wafer in the direction along the X-axis.

[0084] In steps S10 and S30, the curved surfaces formed on the holding surface 16a of the chuck table 16 and the upper surface 17a of the workpiece for adjustment 17 are curved surfaces that roughly correspond to portions of the side surfaces of an oblique cylinder. If an oblique cylinder corresponding to this curved surface is imagined, the curvature of the curved surface will vary depending on the angle of the axis of the imaginary oblique cylinder. The uneven thickness of the workpiece for adjustment 17 in the X-axis direction shown in Figure 4(B) is due to this difference in curvature.

[0085] The relationship between the angle of the axis of the imaginary oblique cylinder and the shape of the curved surface formed on the workpiece to be ground is shown in Figures 5(A) and 5(B). When grinding a material that is easy to grind, the amount of rise of the grinding surface due to wear is small, so the angle of the imaginary oblique cylinder with respect to the vertical (hereinafter referred to as the "inclination" for convenience) becomes large, as shown in Figure 5(A). When grinding a material that is difficult to grind, the amount of rise of the grinding surface due to wear is large, so the inclination of the imaginary oblique cylinder becomes small, as shown in Figure 5(B).

[0086] Then, a curved surface is formed on the upper surface of the workpiece to be ground, the shape of which corresponds to the lower part of the side surface of each imaginary oblique cylinder. The curvature of this curved surface increases as the inclination of the imaginary oblique cylinder decreases (see the cross-sectional views along the XZ plane in Figures 5(A) and 5(B)).

[0087] The inclination of the imaginary oblique cylinder (corresponding to FIG. 5(B)) corresponding to the curved surface of the holding surface 16a of the chuck table 16 is smaller than the inclination of the imaginary oblique cylinder (corresponding to FIG. 5(A)) corresponding to the curved surface of the upper surface 17a of the workpiece for adjustment 17, so the curvature of the holding surface 16a of the chuck table 16 is larger than the curvature of the upper surface 17a of the workpiece for adjustment 17. This causes the thickness deviation shown in FIG. 4(B).

[0088] If the workpiece for adjustment 17 is more difficult to grind than the material of the chuck table 16, the thickness distribution of the workpiece for adjustment 17 after grinding will be the opposite of the example shown in Figures 4(A) and 4(B). That is, in the Y-axis direction, the front is thinner and the rear is thicker, and in the X-axis direction, both ends are thicker than the middle.

[0089] The curvature of the curved surface formed by grinding (the shape of the side surface of the imaginary oblique cylinder) varies depending not only on the amount of elevation of the grinding surface but also on the inclination (tilt angle around the X axis) of the grinding surface relative to the moving direction (Y axis direction).

[0090] Based on this distribution of thickness along the X-axis and Y-axis directions, values ​​related to the relative movement along the Z-axis between the grinding wheel 40 and the chuck table 16, and the tilt angles of the chuck table 16 and the grinding wheel 40 are set (Z-axis movement setting process: step S50, tilt angle setting process: step S60).

[0091] As described above, the curved surface formed on the holding surface 16a of the chuck table 16 during self-grinding by creep feed grinding and the curved surface formed on the upper surface 11a of the material (workpiece 11) held on the holding surface 16a by subsequent creep feed grinding each correspond to the side surfaces of the imaginary oblique cylinder. In other words, if the shapes and orientations of the imaginary oblique cylinders corresponding to both curved surfaces are the same, the curved surfaces formed on both will be parallel, and theoretically the thickness of the workpiece 11, defined as the distance between these curved surfaces, will be uniform.

[0092] The shape of the imaginary oblique cylinder varies depending on the amount of wear of the grinding wheel 40b due to creep feed grinding, the movement of the grinding wheel 40 along the Z axis, and the angle between the rotation plane of the grinding wheel 40b and the chuck table 16. Therefore, in steps S50 and S60, values ​​related to the movement of the grinding wheel 40 along the Z axis, and the tilt angles of the chuck table 16 and grinding wheel 40 are set.

[0093] This causes the shape and orientation of the imaginary oblique cylinder corresponding to the curved surface formed on the upper surface 11a of the workpiece 11 in the subsequent creep feed grinding (workpiece grinding process; step S80) to approach the imaginary oblique cylinder corresponding to the curved surface formed on the holding surface 16a of the chuck table 16.

[0094] In step S50, based on the thickness distribution measured in step S40, a value related to the relative movement along the Z axis between the grinding wheel 40 and the chuck table 16 is set. In the case of this embodiment, the "value related to the relative movement along the Z axis" set here is the value related to the movement of the grinding wheel 40 along the Z axis (vertical direction) during creep feed grinding (indicated by the symbol z in FIG. 6).

[0095] Furthermore, the "value z related to movement" refers to, for example, the initial value and target value of the position of the grinding wheel 40 when grinding is being performed, or the amount of movement (speed) per unit time, the amount of movement of the lift table 24 in the vertical direction per amount of movement of the horizontal movement table 8 in the horizontal direction, the total distance that the grinding wheel 40 moves along the Z axis from the start to the end of creep feed grinding, etc. As long as the relative movement between the grinding wheel 40 and the chuck table 16 along the Z axis can be appropriately specified, the parameter set as the value z related to movement may be any, such as speed, distance, or position.

[0096] 6 and 7, the inclination of the grinding wheel 40 and chuck table 16, and the curvature of the holding surface 16a of the chuck table 16 and the workpiece to be adjusted 17 are emphasized. In addition, in Fig. 7, the chuck table 16 is depicted as being approximately rectangular in order to clearly show the inclination of the chuck table 16 (usually, the shape of the chuck table is set to be the same as the shape of the article to be held thereon, so if the workpiece, which is a wafer, is disk-shaped, the chuck table is often also formed to be circular in plan view. However, there is no particular problem even if the shapes of the chuck table and the workpiece in plan view are different).

[0097] In the tilt angle setting step S60, the tilt angles of the chuck table 16 and the grinding wheel 40 are set based on the thickness distribution measured in the thickness measuring step S40.

[0098] The adjustment of each value according to the thickness distribution (adjustment of the value z relating to movement along the Z-axis direction; step S50, adjustment of the tilt angle; step S60) will be described below. Regarding step S60, we will first explain how to set the tilt angle around the X-axis (indicated by the symbols θ and ω in FIG. 6).

[0099] If the thickness of the adjustment workpiece 17 measured at multiple positions in step S40 reveals a bias in the thickness distribution in the Y-axis direction, the bias can be corrected by adjusting the value z relating to the movement along the Z-axis or the tilt angle θ of the chuck table 16 about the X-axis.

[0100] If the thickness of the adjustment workpiece 17 is thicker at the front and thinner at the rear in the direction of movement of the chuck table 16 during creep feed grinding, and you want to correct this by using the value z for movement along the Z axis, set the amount of upward movement of the grinding wheel 40 to be greater than the initial value (the value set in the previous step S10; for example, zero). If the thickness deviation in the Y axis direction is large, set the difference from the initial value accordingly.

[0101] Conversely, if the thickness of the adjustment workpiece 17 is thinner at the front and thicker at the rear in the direction of movement of the chuck table 16 during creep feed grinding, and you want to correct this by using the value z related to movement along the Z axis, set the upward movement amount of the grinding wheel 40 to be smaller than the initial value (if the initial value is zero, set it to a negative value).

[0102] Furthermore, if the thickness of the adjustment workpiece 17 is thicker at the front and thinner at the rear in the direction of movement of the chuck table 16 during creep feed grinding, and if it is desired to correct this imbalance by adjusting the tilt angle θ of the chuck table 16 about the X axis, the tilt is adjusted so that the front of the chuck table 16 is relatively raised and the rear is relatively lowered in the direction of movement of the chuck table 16 during grinding.

[0103] Conversely, if the thickness of the adjustment workpiece 17 is thinner at the front and thicker at the rear in the direction of movement of the chuck table 16 during creep feed grinding, and this needs to be corrected by the tilt angle θ, the tilt is adjusted so that the front of the chuck table 16 is relatively lowered and the rear is relatively raised in the direction of movement of the chuck table 16 during grinding.

[0104] If the thickness of the adjustment workpiece 17 measured at multiple positions in step S40 reveals a bias in the thickness distribution in the X-axis direction, the bias can be corrected by adjusting at least one of the value z relating to the movement of the grinding wheel 40 and chuck table 16 along the Z-axis or the tilt angle ω of the grinding wheel 40 about the X-axis.

[0105] The curvature along the X-axis of the curved surface formed on the upper surface 11a of the workpiece 11 held on the holding surface 16a of the chuck table 16 varies depending on the amount of rise of the grinding surface due to wear of the grinding wheel 40b during grinding, the amount of movement of the grinding wheel 40 itself, and the inclination angle ω of the grinding wheel 40.

[0106] That is, the greater the amount of elevation of the grinding surface relative to the chuck table 16, the greater the curvature along the X-axis. Furthermore, if the elevation of the grinding surface due to wear and the amount of movement of the grinding wheel 40 are not taken into consideration, the greater the value of the inclination angle ω relative to the XY plane, the greater the curvature.

[0107] As a result of measuring the thickness distribution in step S40, if the adjustment workpiece 17 becomes thinner toward both ends in the X-axis direction, this indicates that the curvature of the upper surface 17a of the adjustment workpiece 17 is smaller than the curvature of the holding surface 16a of the chuck table 16.

[0108] In this case, if you want to correct the thickness imbalance in the X-axis direction by using the value z related to the movement along the Z-axis, set this value z to a large value (increase the amount of movement of the grinding wheel 40 away from the chuck table 16 in the Z-axis direction during grinding).

[0109] When it is desired to correct the same thickness deviation by adjusting the inclination angle ω of the grinding wheel 40, the inclination angle ω of the grinding wheel 40 is adjusted so that the inclination of the grinding wheel 40 with respect to the XY plane becomes larger.

[0110] If the adjustment workpiece 17 becomes thicker toward both ends in the X-axis direction, this indicates that the curvature of the upper surface 17a of the adjustment workpiece 17 is greater than the curvature of the holding surface 16a of the chuck table 16.

[0111] In this case, if you want to correct the thickness imbalance in the X-axis direction by using the value z related to the movement along the Z-axis, set this value z to a small value (to reduce the amount of movement of the grinding wheel 40 away from the chuck table 16 in the Z-axis direction during grinding).

[0112] When it is desired to correct the same thickness deviation by adjusting the inclination angle ω of the grinding wheel 40, the inclination angle ω of the grinding wheel 40 is adjusted so that the inclination of the grinding wheel 40 with respect to the XY plane becomes smaller.

[0113] From the above, when attempting to correct the thickness distribution along the X-axis direction and the Y-axis direction of the adjustment workpiece 17 using a mechanism such as that provided in the grinding device 2 of this embodiment, there are, for example, the following methods 1 to 3. 1) The value z relating to the relative movement along the Z axis between the chuck table 16 and the grinding wheel 40 is adjusted based on the thickness deviation (curvature) in the X axis direction, and the tilt angle θ of the chuck table 16 around the X axis is adjusted based on the thickness deviation (tilt) in the Y axis direction. 2) Based on the thickness deviation (tilt) in the Y-axis direction, the value z relating to the relative movement along the Z-axis between the chuck table 16 and the grinding wheel 40 is adjusted, and based on the thickness deviation (curvature) in the X-axis direction, the tilt angle ω of the grinding wheel 40 around the X-axis is adjusted. 3) Combine steps 1 and 2 above.

[0114] In theory, if the elevation of the grinding surface during self-grinding can be set equal to the elevation of the grinding surface during grinding of the adjustment workpiece 17 or the workpiece 11 by setting the value z relating to the movement along the Z-axis, it is possible to obtain a workpiece 11 with a sufficiently uniform thickness in the subsequent grinding without setting the inclination angles θ and ω. However, in practice, this is not always the case. This is because variations in the grinding load on the grinding wheel 40b can cause the grinding surface to tilt.

[0115] Therefore, in order to obtain a workpiece 11 with a more uniform thickness, it is effective to set not only the value z relating to the movement along the Z axis but also the tilt angles θ and ω.

[0116] In step S60, in addition to the tilt angles θ and ω about the X axis as described above, tilt angles about the Y axis (shown by symbols α and β in FIG. 7) can also be set.

[0117] 4(B), the thickness distribution of the adjustment workpiece 17 is roughly symmetrical in the X-axis direction, but it is possible that the thickness distribution in the X-axis direction may become asymmetrical due to factors such as uneven load on the grinding wheel 40b (thickness distribution in such cases is not shown in the figure). Such asymmetrical deviation can be corrected by adjusting either the tilt angle α of the chuck table 16 or the tilt angle β of the grinding wheel 40.

[0118] The setting and adjustment of the inclination angles θ, ω, α, and β may be performed for both or only one of the chuck table 16 and the grinding wheel 40. Also, depending on the embodiment, only one of steps S50 and S60 may be executed.

[0119] Once the movement amount and tilt angle have been set, the setting value z for the movement of the grinding wheel 40 along the Z-axis relative to the chuck table 16 during grinding, the tilt angles θ and α of the grinding wheel 40, and the tilt angles ω and β of the chuck table 16 are adjusted according to the settings, and then the workpiece 11 is held on the holding surface 16a of the chuck table 16 (workpiece holding process; step S70), and grinding is performed (workpiece grinding process; step S80).

[0120] The chuck table 16 is positioned so as not to overlap the grinding wheel 40 in a plan view, and the position of the grinding wheel 40 is adjusted so that the lower end of the grinding stone 40b is slightly lower than the upper surface 11a of the workpiece 11. As the grinding wheel 40 rotates, the chuck table 16 moves along the Y-axis, grinding the entire upper surface 11a of the workpiece 11 in the Y-axis direction.

[0121] During this time, the chuck table 16 and the grinding wheel 40 are supported at the set inclination angles θ, ω, α, and β. When a value z relating to the movement of the grinding wheel 40 along the Z-axis is set, the grinding wheel 40 grinds the upper surface 11a of the workpiece 11 while moving up or down in the vertical direction.

[0122] If the setting value z for movement and the tilt angles θ, ω, α, and β in steps S50 and S60 are set appropriately, a workpiece 11 having a thickness distribution such as that shown in Figures 8(A) and 8(B) can be obtained in step S80. That is, the workpiece 11 has a substantially uniform thickness in both the Y-axis and X-axis directions. If a workpiece 11 with a sufficiently uniform thickness is obtained, steps S70 and S80 can be repeated with the same settings to continuously obtain workpieces 11 with similar thicknesses.

[0123] Incidentally, the above describes the procedure in which, after self-grinding of the chuck table 16 (step S10), the workpiece for adjustment 17 is ground once (steps S20 to S30), and then the movement amount and tilt angle are set based on the measurement (steps S40 to S60), followed by grinding of the workpiece 11 (steps S70 to S80). However, it is not always possible to grind the workpiece 11 with just one adjustment like this.

[0124] In other words, it may be desirable to set the travel distance and tilt angle and repeat grinding based on them several times to adjust the set values ​​before moving on to grinding the actual workpiece 11. An example of such a procedure based on trial and error is shown in Figure 9.

[0125] In the flowchart of Figure 9, first, grinding of the adjustment workpiece 17 is performed (steps S20 to S30), and after measuring its thickness (step S40), it is determined whether the measured thickness of the adjustment workpiece 17 is uniform to an acceptable extent (step S100).

[0126] If it is determined that the thickness of the workpiece for adjustment 17 is sufficiently uniform, the process proceeds to grinding the workpiece 11 (steps S70 to S80); if the thickness is not sufficiently uniform, the movement amount and tilt angle are set (steps S50 to S60), and the workpiece for adjustment 17 is ground again based on these (steps S20 to S30).

[0127] The thickness is measured again (step S40), and this is repeated until it is determined that the thickness of the adjustment workpiece 17 is sufficiently uniform, and the set values ​​are adjusted in steps S50 to S60. Once it is determined that a sufficiently uniform thickness has been obtained, the process moves to grinding the workpiece 11 (steps S70 to S80).

[0128] In the above steps shown in Figures 3 and 9, at least some of the setting of values ​​such as the value z relating to the movement of the grinding wheel 40 along the Z axis relative to the chuck table 16, and the inclination angles θ, ω, α, and β of the chuck table 16 and the grinding wheel 40 (steps S50 to S60) may be performed by a person (operator) or may be performed automatically by the controller 42.

[0129] When the controller 42 executes the grinding, for example, data on the thickness of the workpiece for adjustment 17 (measurements taken by measuring instruments 48a and 48b, thickness values ​​calculated thereby, thickness distribution in the Y-axis and X-axis directions, etc.) and functions for deriving each value (movement amount z, tilt angles θ, ω, α, β) based on the data are stored in the memory unit 42e, and the calculation unit 42d calculates each value using these. Based on this, the position control unit 42b and tilt control unit 42c adjust the movement and tilt angle of each unit to perform grinding.

[0130] When each value is calculated manually, for example, the person calculates each value (value z related to movement, tilt angles θ, ω, α, β) based on measurement data related to the thickness of the workpiece for adjustment 17 and inputs this to the input / output unit 42f. Based on this, the position control unit 42b and tilt control unit 42c adjust the movement and tilt angle of each unit and perform grinding. Furthermore, the thickness of the workpiece for adjustment 17 may be measured outside the grinding device 2 instead of using the thickness measurement unit 48.

[0131] 3 and 9 are merely examples, and the steps described here may be rearranged, omitted, or additional steps may be added, or the content of each step may be changed. For example, S60 may be performed before S50, or these steps may be performed simultaneously.

[0132] Furthermore, the relative positions, movements, and angles of each part in the grinding machine and each process are relative. For example, it is theoretically possible to move the chuck table to adjust the amount of movement along the Z axis, or to move the grinding wheel along the Y axis during grinding. It is also theoretically possible to set the direction of movement of the chuck table to be vertical and the direction of movement of the grinding wheel to be horizontal.

[0133] According to the grinding device and grinding method described above, the shape of the curved surface formed on the holding surface 16a of the chuck table 16 by self-grinding is made closer to the shape of the curved surface formed on the upper surface 11a of the workpiece 11 by subsequent grinding, thereby making it possible to grind the workpiece 11 to a uniform thickness.

[0134] It is particularly important to correct differences in the shape of the ground surface caused by differences in the amount of lift of the ground surface due to differences in the materials of the chuck table 16 and the workpiece 11. For example, if the problem is tilt in the direction of movement of the chuck table (uneven thickness in the Y-axis direction) caused by the lift of the ground surface due to wear of the grinding wheel, this can be solved by moving the grinding wheel vertically (in the Z-axis direction), for example. However, this alone is not enough to eliminate uneven thickness in the X-axis direction caused by differences in curvature.

[0135] Self-grinding of the chuck table is an effective technique for improving the uniformity of the thickness of a workpiece while taking into account differences in curvature. However, as mentioned above, even with self-grinding, differences in the material can sometimes result in uneven thickness in both the Y-axis and X-axis directions.

[0136] Therefore, as in the above embodiment, assuming that the chuck table 16 is self-grinded and that thickness imbalances may still occur in the workpiece 11, by adjusting the value z relating to the movement of the grinding wheel 40 along the Z axis relative to the chuck table 16, or at least some of the inclination angles θ, ω, α, and β of the chuck table 16 and the grinding wheel 40, it is possible to match the shapes of the curved surfaces formed on the chuck table 16 and the workpiece 11 by grinding, and obtain a more uniform thickness for the workpiece 11.

[0137] The structures, methods, etc. according to the above-described embodiments are not limited to the above-described embodiments, and may be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0138] 2: Grinding device, 4: Horizontal movement mechanism, 6: Horizontal guide rail, 8: Horizontal movement table 10: horizontal ball screw, 11: workpiece (wafer), 11a: upper surface 12: horizontal movement motor, 14: support table, 16: chuck table, 16a: holding surface 17: Adjustment workpiece, 17a: Top surface, 18: Support structure, 20: Lifting mechanism 22: Elevation guide rail, 24: Elevation table, 26: Elevation ball screw 28: lifting motor, 32: grinding mechanism, 34: spindle housing 36: Rotating body (spindle), 40: Grinding wheel, 40a: Wheel base 40b: grinding wheel, 42: controller, 42a: rotation control section, 42b: position control section 42c: tilt control unit, 42d: calculation unit, 42e: storage unit, 42f: input / output unit 44: Tilt angle adjustment mechanism, 46: Tilt angle adjustment mechanism, 48: Thickness measurement unit 48a: First measuring instrument, 48b: Second measuring instrument

Claims

1. a chuck table having a holding surface for holding a workpiece; a grinding mechanism having a spindle attached to a grinding wheel having a grinding stone fixed thereto and rotating together with the grinding wheel; a Y-axis movement mechanism that moves the grinding wheel and the chuck table relative to each other in a direction along the grinding surface formed by the rotating grinding stone; a storage unit for storing data; a direction parallel to the direction in which the grinding mechanism and the chuck table move relatively by the Y-axis moving mechanism is defined as the Y-axis, a direction perpendicular to the Y-axis and along the rotation axis of the grinding wheel is defined as the Z-axis, and a direction perpendicular to the Y-axis and the Z-axis is defined as the X-axis, a Z-axis movement mechanism that moves the grinding wheel and the chuck table relatively along the Z-axis; or An inclination angle adjustment mechanism for adjusting the inclination angle of the grinding wheel or the chuck table about the X axis. and at least one of a controller that controls the Z-axis movement mechanism or the tilt angle adjustment mechanism, the memory unit is configured to: perform self-grinding to grind the holding surface of the chuck table by rotating the grinding wheel while the chuck table and the grinding wheel are moved relatively along the Y axis without holding the workpiece on the chuck table; then hold the workpiece to be adjusted on the holding surface of the chuck table; and move the chuck table and the grinding wheel relatively along the Y axis while rotating the grinding wheel to grind the workpiece to be adjusted; and then store data relating to the thickness measured for the workpiece to be adjusted; The controller When controlling the Z-axis movement mechanism, a value relating to the relative movement of the grinding wheel and the chuck table along the Z-axis is adjusted based on data relating to the thickness of the workpiece for adjustment stored in the memory unit; When controlling the tilt angle adjusting mechanism, at least one of the tilt angle of the grinding wheel and the tilt angle of the chuck table is adjusted based on data relating to the thickness of the workpiece for adjustment stored in the memory unit. A grinding device characterized by:

2. 2. The grinding device according to claim 1, wherein the Z-axis movement mechanism is configured to adjust a value z relating to the relative movement of the grinding wheel and the chuck table along the Z-axis based on the thickness distribution along the X-axis of the workpiece for adjustment stored in the memory unit.

3. 2. The grinding device according to claim 1, wherein the tilt angle adjustment mechanism is configured to adjust the tilt angle θ of the chuck table about the X-axis based on the thickness distribution along the Y-axis of the workpiece for adjustment stored in the memory unit.

4. 2. The grinding device according to claim 1, wherein the tilt angle adjustment mechanism is configured to adjust at least one of the tilt angle α of the chuck table about the Y axis and the tilt angle β of the grinding wheel about the Y axis, based on the thickness distribution along the X axis of the workpiece for adjustment stored in the memory unit.

5. a chuck table having a holding surface for holding a workpiece; a grinding mechanism having a spindle to which a grinding wheel having a grinding stone is attached and which rotates together with the grinding wheel; a grinding method using a grinding device equipped with a Y-axis movement mechanism that moves the grinding wheel and the chuck table relatively along a grinding surface formed by the rotating grinding stone, a holding surface grinding step in which, without holding the workpiece on the chuck table, the chuck table and the grinding wheel are moved relatively along the Y axis while rotating the grinding wheel, thereby performing self-grinding to grind the holding surface of the chuck table; a workpiece-to-be-adjusted holding step of holding the workpiece to be adjusted on the holding surface of the chuck table; a grinding step of grinding the workpiece to be adjusted by relatively moving the chuck table and the grinding wheel along the Y axis while rotating the grinding wheel; a thickness measuring step of measuring the thickness of the workpiece for adjustment at a plurality of positions after the workpiece for adjustment grinding step; The direction parallel to the direction in which the grinding mechanism and the chuck table move relatively by the Y-axis movement mechanism is defined as the Y-axis. The direction perpendicular to the Y axis and along the rotation axis of the grinding wheel is the Z axis. The direction perpendicular to the Y-axis and Z-axis is the X-axis, a Z-axis movement setting step of setting a value related to the relative movement along the Z-axis between the grinding wheel and the chuck table based on the thickness distribution of the workpiece for adjustment measured in the thickness measuring step; or a tilt angle setting step of setting at least one of the tilt angle of the grinding wheel and the tilt angle of the chuck table; a workpiece holding step of holding a workpiece on the holding surface of the chuck table; a workpiece grinding step in which the chuck table and the grinding wheel are moved relative to each other while rotating the grinding wheel based on the settings made in the Z-axis movement setting step or the inclination angle setting step, thereby grinding the workpiece; A grinding method comprising:

6. 6. The grinding method according to claim 5, wherein in the Z-axis movement setting step, a value z relating to the relative movement of the grinding wheel and the chuck table along the Z-axis is set based on the thickness distribution along the X-axis of the workpiece for adjustment.

7. 6. The grinding method according to claim 5, wherein the tilt angle setting step adjusts the tilt angle θ of the chuck table about the X-axis based on the thickness distribution along the Y-axis of the workpiece for adjustment.

8. 6. The grinding method according to claim 5, wherein in the inclination angle setting step, at least one of the inclination angle α of the chuck table about the Y axis and the inclination angle β of the grinding wheel about the Y axis is adjusted based on the thickness distribution along the X axis of the workpiece for adjustment.

9. 6. The grinding method according to claim 5, wherein the adjustment workpiece is made of the same material as the workpiece.

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