Grinding device and grinding method for workpiece

Abstract

To provide a grinding device capable of reducing the consumption of a grounding liquid while suppressing the occurrence of a processing failure.SOLUTION: A grinding device for grinding a workpiece includes a chuck table having a holding surface for holding a workpiece, a grounding unit having a spindle with a grounding wheel including a grindstone attached to a tip, a movement mechanism for relatively moving the chuck table and the grinding unit along a direction perpendicular to a rotation shaft of the spindle, a grinding liquid supply unit for supplying the grinding liquid to a processing region where the workpiece is brought into contact with the grindstone from the outside of the grinding wheel, and a control unit. The control unit includes a flow rate information storage part for storing flow rate information showing a flow rate of the grinding liquid set to make the amount of the grinding liquid to be supplied to the processing region more as a contact area between the workpiece and the grindstone becomes large, and a flow rate adjustment part for adjusting the flow rate of the grinding liquid to be supplied to the processing region on the basis of the flow rate information stored in the flow rate information storage part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a grinding device for grinding a workpiece, and a method for grinding a workpiece using the grinding device to grind the workpiece.

Background Art

[0002] In the manufacturing process of device chips, a wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets (division planned lines) intersecting each other is used. By dividing this wafer along the streets, a plurality of device chips each having a device can be obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] In recent years, with the miniaturization of electronic devices, there has been a demand for thinning of device chips. Therefore, a process of grinding and thinning the wafer before division may be performed using a grinding device. The grinding device includes a chuck table including a holding surface for holding a workpiece, and a grinding unit for grinding the workpiece. The grinding unit includes a spindle, and a grinding wheel including a plurality of grinding wheels is attached to the tip of the spindle.

[0004] When grinding a workpiece such as a wafer using a grinding device, the positional relationship between the chuck table and the grinding unit is adjusted so that the center of the workpiece held by the chuck table overlaps the orbit of the grinding wheel. Then, while rotating the chuck table and the grinding wheel respectively, the grinding wheel is lowered along the machining feed direction (vertical direction) parallel to the rotation axis of the spindle. As a result, the lower surface of the grinding wheel comes into contact with the upper surface side of the workpiece, and the workpiece is ground. Such a grinding method is called infeed grinding.

[0005] On the other hand, for grinding a workpiece, a grinding method called creep feed grinding may be used. In creep feed grinding, the positional relationship between the chuck table and the grinding unit is adjusted such that the grinding wheel is positioned outside the workpiece and the lower surface of the grinding wheel is positioned below the upper surface of the workpiece. Then, while rotating the grinding wheel, the chuck table is moved along the machining feed direction (horizontal direction) perpendicular to the rotation axis of the spindle. As a result, the side surface of the grinding wheel contacts the upper surface side of the workpiece, and the workpiece is ground (see Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In creep feed grinding, the entire workpiece is ground and thinned by bringing the rotating grinding wheel into contact with the workpiece from one end to the other end along the machining feed direction. At this time, the contact area between the workpiece and the grinding wheel changes as the machining feed progresses.

[0008] Also, when grinding the workpiece, a liquid (grinding fluid) such as pure water is supplied to the area where the workpiece and the grinding wheel come into contact (machining area). As a result, the workpiece and the grinding wheel are cooled, and the chips (machining chips) generated by the grinding process are washed away. If the supply amount of the grinding fluid is insufficient, the entire machining area will not be sufficiently supplied with the grinding fluid, resulting in insufficient cooling of the workpiece and the grinding wheel and insufficient removal of the machining chips, making it easy for machining defects to occur. Therefore, in creep feed grinding, the flow rate of the grinding fluid is set so that the entire machining area is sufficiently supplied with the grinding fluid even when the contact area between the workpiece and the grinding wheel is at its maximum.

[0009] However, when the flow rate of the grinding fluid is set as described above, in the initial stage of grinding where the contact area between the workpiece and the grinding wheel is small (when grinding one end of the workpiece) or in the final stage (when grinding the other end of the workpiece), excessive grinding fluid that does not contribute to cooling the workpiece and the grinding wheel or removing the machining chips is supplied. As a result, a large amount of grinding fluid is consumed in the grinding process, increasing the cost.

[0010] The present invention has been made in view of such problems, and an object thereof is to provide a grinding apparatus capable of reducing the consumption amount of the grinding fluid while suppressing the occurrence of machining defects, and a method for grinding a workpiece using the grinding apparatus.

Means for Solving the Problems

[0011] According to one 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; a grinding unit having a spindle to which a grinding wheel including a grinding stone is attached at a tip; a moving mechanism for relatively moving the chuck table and the grinding unit along a direction perpendicular to the rotation axis of the spindle; a grinding fluid supply unit for supplying grinding fluid from the outside of the grinding wheel to a machining area where the workpiece and the grinding stone come into contact; and a control unit. The control unit includes: a flow rate information storage unit for storing flow rate information indicating the flow rate of the grinding fluid set such that the amount of the grinding fluid supplied to the machining area increases as the contact area between the workpiece and the grinding stone increases; and a flow rate adjustment unit for adjusting the flow rate of the grinding fluid supplied to the machining area based on the flow rate information stored in the flow rate information storage unit. , the flow rate information includes the position information of the chuck table or the contact area, and the flow rate of the grinding fluid corresponding to the position information or the contact area A grinding apparatus is provided.

[0013] Also, according to another aspect of the present invention, there is provided a method for grinding a workpiece using a grinding apparatus, the grinding apparatus including a chuck table having a holding surface for holding the workpiece and a grinding unit having a spindle to which a grinding wheel including a grinding stone is attached at a tip end, the method including a holding step of holding the workpiece by the chuck table and a grinding step of relatively moving the chuck table and the grinding unit along a direction perpendicular to a rotation axis of the spindle while supplying a grinding fluid to a machining area where the workpiece and the grinding stone come into contact with each other from outside of the grinding wheel, and grinding the workpiece with the grinding stone, wherein in the grinding step, Based on the flow rate information including the position information of the chuck table or the contact area between the workpiece and the grinding wheel, and the flow rate of the grinding fluid corresponding to the position information or the contact area, the there is provided a method for grinding a workpiece, in which the flow rate of the grinding fluid is adjusted such that the larger the contact area is, the larger the amount of the grinding fluid supplied to the machining area becomes.

Advantages of the Invention

[0014] In the grinding apparatus and the method for grinding a workpiece according to one aspect of the present invention, the flow rate of the grinding fluid is adjusted such that the larger the contact area between the workpiece and the grinding stone is, the larger the amount of the grinding fluid supplied to the machining area becomes. Thereby, an appropriate amount of the grinding fluid is supplied to the machining area according to the contact area between the workpiece and the grinding stone, and it becomes possible to reduce the consumption amount of the grinding fluid while suppressing the occurrence of machining defects.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment according to an aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of the grinding apparatus according to the present embodiment will be described. FIG. 1 is a perspective view showing a grinding apparatus 2. In FIG. 1, the X-axis direction (machining feed direction, first horizontal direction, front-rear direction), the Y-axis direction (second horizontal direction, left-right direction), and the Z-axis direction (vertical direction, up-down direction, height direction) are perpendicular to each other.

[0017] The grinding apparatus 2 includes a base 4 that supports or houses each component constituting the grinding apparatus 2. On the upper surface side of the base 4, a rectangular parallelepiped-shaped opening 4a is formed such that its longitudinal direction is along the X-axis direction. Further, at the rear end portion on the upper surface side of the base 4, a rectangular parallelepiped-shaped support structure 6 is provided along the Z-axis direction.

[0018] Inside the opening 4a, a chuck table (holding table) 8 for holding a workpiece, which is an object to be machined by the grinding apparatus 2, is provided. The upper surface of the chuck table 8 is a flat surface that is generally parallel to the horizontal plane (XY plane), and constitutes a holding surface 8a for holding the workpiece. Further, a moving mechanism (moving unit) 10 for moving the chuck table 8 along the machining feed direction (X-axis direction) is connected to the chuck table 8.

[0019] FIG. 2 is a partial cross-sectional side view showing the grinding apparatus 2. In FIG. 2, illustration of some components of the grinding apparatus 2 is omitted. As shown in FIG. 2, the moving mechanism 10 is provided inside the opening 4a of the base 4.

[0020] The moving mechanism 10 includes a flat moving plate 12 that supports the chuck table 8. A nut portion 14 is provided on the back surface side (lower surface side) of the moving plate 12. A ball screw 16 arranged along the X-axis direction is screwed into the nut portion 14. Further, a pulse motor 18 for rotating the ball screw 16 is connected to an end portion of the ball screw 16. And the chuck table 8 is mounted on the front surface side (upper surface side) of the moving plate 12. When the ball screw 16 is rotated by the pulse motor 18, the chuck table 8 and the moving plate 12 move along the X-axis direction.

[0021] Further, a rotation drive source (not shown) such as a motor for rotating the chuck table 8 around a rotation axis (a rotation axis substantially parallel to the Z-axis direction) that is substantially perpendicular to the holding surface 8a of the chuck table 8 is connected to the chuck table 8. That is, the rotation axis of the chuck table 8 is set along a direction perpendicular to the holding surface 8a.

[0022] As shown in FIG. 1, a table cover 20 surrounding the chuck table 8 is provided around the chuck table 8. Further, bellows-shaped dust and splash covers 22 that are extendable and retractable along the X-axis direction are provided in front of and behind the table cover 20. The table cover 20 and the dust and splash covers 22 cover the components of the moving mechanism 10 provided inside the opening 4a.

[0023] A moving mechanism (moving unit) 24 is provided on the front surface side of the support structure 6. The moving mechanism 24 includes a pair of guide rails 26 arranged along the Z-axis direction. Further, a flat moving plate 28 is slidably mounted on the pair of guide rails 26 along the guide rails 26.

[0024] On the back side (rear side) of the moving plate 28, a nut portion (not shown) is provided. A ball screw 30 arranged along the Z-axis direction is screwed into this nut portion between a pair of guide rails 26. Further, a pulse motor 32 for rotating the ball screw 30 is connected to an end portion of the ball screw 30. When the ball screw 30 is rotated by the pulse motor 32, the moving plate 28 moves (moves up and down) in the Z-axis direction along the guide rails 26.

[0025] A support member 34 that protrudes forward from the surface (front surface) of the moving plate 28 is fixed to the moving plate 28. The support member 34 supports a grinding unit 36 that performs grinding on the workpiece 11. The grinding unit 36 includes a cylindrical housing 38 supported by the support member 34. Further, a cylindrical spindle 40 arranged along the Z-axis direction is accommodated in the housing 38.

[0026] The tip end portion (lower end portion) of the spindle 40 protrudes downward from the lower surface of the housing 38. And a disk-shaped mount 42 made of metal or the like is fixed to the tip end portion of the spindle 40. Further, a rotational drive source (not shown) such as a motor for rotating the spindle 40 is connected to the base end portion (upper end portion) of the spindle 40.

[0027] An annular grinding wheel 44 for grinding the workpiece 11 is mounted on the lower surface side of the mount 42. For example, the grinding wheel 44 is fixed to the mount 42 by a fixture (not shown) such as a bolt. Thereby, the grinding wheel 44 is mounted on the tip end portion of the spindle 40 via the mount 42.

[0028] The grinding wheel 44 includes an annular wheel base 46 and a plurality of grinding wheels 48 fixed to the wheel base 46. The wheel base 46 is made of a metal such as stainless steel or aluminum, or a resin, and is formed to have approximately the same diameter as the mount 42. And a plurality of grinding wheels 48 formed in a rectangular parallelepiped shape, for example, are arranged at approximately equal intervals along the outer peripheral edge of the wheel base 46 on the lower surface side of the wheel base 46.

[0029] The grinding wheel 48 includes abrasive grains made of diamond, cBN (cubic Boron Nitride), etc., and a bonding material (bonding agent) that fixes the abrasive grains. As the bonding material, a metal bond, a resin bond, a vitrified bond, etc. can be used. However, there are no restrictions on the material, shape, structure, size, etc. of the grinding wheel 48, and the number of grinding wheels 48 fixed to the wheel base 46 can also be arbitrarily set.

[0030] The grinding wheel 44 rotates around a rotation axis that is generally parallel to the Z-axis direction by the power transmitted from the rotation drive source via the spindle 40 and the mount 42. That is, the rotation axis of the grinding wheel 44 is set along a direction parallel to the rotation axis of the spindle 40.

[0031] In front of the grinding unit 36, a columnar grinding fluid supply unit 50 that supplies a liquid (grinding fluid) such as pure water to the grinding unit 36 is provided. The grinding fluid supply unit 50 is positioned above the opening 4a of the base 4 so as to overlap the movement path of the chuck table 8. For example, the grinding fluid supply unit 50 is composed of a pipe, a tube, etc. whose length is equal to or greater than the diameter of the holding surface 8a of the chuck table 8, and is arranged along the width direction (Y-axis direction) of the opening 4a.

[0032] Note that there are no restrictions on the installation method of the grinding fluid supply unit 50. For example, the grinding fluid supply unit 50 is fixed to the upper surface of the base 4 or the grinding unit 36 via a predetermined connecting member (not shown). Details of the grinding fluid supply unit 50 will be described later (see FIGS. 4(A) to 4(C)).

[0033] The grinding fluid supply unit 50 is connected to a liquid supply source 54 via a valve 52. As the valve 52, for example, an electromagnetic valve is used. The liquid supply source 54 is, for example, a factory facility (liquid supply facility) provided in the factory where the grinding device 2 is installed, and supplies a liquid such as pure water used as the grinding fluid. By controlling the opening and closing or the opening degree of the valve 52, the flow rate of the grinding fluid supplied from the liquid supply source 54 is adjusted.

[0034] Further, the grinding device 2 includes a control unit (control section, control device) 56 connected to each component of the grinding device 2 (chuck table 8, moving mechanism 10, moving mechanism 24, grinding unit 36, grinding fluid supply unit 50, valve 52, etc.). The control unit 56 generates a control signal for controlling the operation of the components of the grinding device 2.

[0035] For example, the control unit 56 is constituted by a computer and includes an arithmetic unit that performs arithmetic operations for operating the grinding device 2, and a storage unit that stores various types of information (data, programs, etc.) used for operating the grinding device 2. The arithmetic unit is configured to include a processor such as a CPU (Central Processing Unit). Further, the storage unit is configured to include memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0036] Next, a specific example of a method for grinding a workpiece using the grinding device 2 will be described. Hereinafter, as an example, creep feed grinding in which the chuck table 8 and the grinding wheel 44 are relatively moved along a direction (X-axis direction) perpendicular to the rotation axis of the spindle 40 to machine the workpiece will be described.

[0037] First, the workpiece 11 is held by the chuck table 8 (holding step). FIG. 3 is a side view showing the chuck table 8 and the grinding unit 36 in the holding step.

[0038] For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor material such as silicon, and has surfaces (first surface) 11a and back surfaces (second surface) 11b that are generally parallel to each other. The workpiece 11 is partitioned into a plurality of rectangular regions by a plurality of streets (lines to be divided) arranged in a grid pattern so as to intersect each other. Further, on the surface 11a side of the plurality of regions partitioned by the streets, devices (not shown) such as IC (Integrated Circuit), LSI (Large Scale Integration), LED (Light Emitting Diode), and MEMS (Micro Electro Mechanical Systems) devices are formed respectively.

[0039] By dividing the workpiece 11 along the streets by cutting, laser processing, or the like, a plurality of device chips each having a device are manufactured. Further, if the workpiece 11 is ground and thinned by the grinding device 2 before dividing the workpiece 11, thinned device chips can be obtained.

[0040] However, there are no restrictions on the type, material, size, shape, structure, etc. of the workpiece 11. For example, the workpiece 11 may be a disk-shaped wafer (substrate) made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, or the like. Further, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the devices, and the workpiece 11 may not have a device formed thereon.

[0041] For example, the workpiece 11 is placed on the chuck table 8 such that the surface 11a side faces the holding surface 8a and the back surface 11b side is exposed upward. Further, the holding surface 8a of the chuck table 8 is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), etc. formed inside the chuck table 8. When the suction force (negative pressure) of the suction source is applied to the holding surface 8a, the workpiece 11 is suction-held by the chuck table 8.

[0042] Note that, by attaching a protective member to the surface 11a side of the workpiece 11, devices or the like formed on the surface 11a side of the workpiece 11 may be protected. In this case, the workpiece 11 is held by the chuck table 8 via the protective member.

[0043] For example, as the protective member, a tape (protective tape) formed in a circular shape having substantially the same diameter as the workpiece 11 is used. The protective tape includes a film-like base material and an adhesive layer (paste layer) provided on the base material. The base material is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy-based, acrylic-based, or rubber-based adhesive or the like. Note that, an ultraviolet curable resin that cures by irradiation with ultraviolet rays can also be used for the adhesive layer.

[0044] Next, the workpiece 11 is ground with the grinding wheel 48 of the grinding wheel 44 (grinding step). In the grinding step, first, the workpiece 11 held by the chuck table 8 and the grinding wheel 48 are separated from each other in the machining feed direction (X-axis direction), and the position relationship between the chuck table 8 and the grinding unit 36 is adjusted so that the lower surface of the grinding wheel 48 is positioned a predetermined distance below the upper surface (back surface 11b) of the workpiece 11.

[0045] Specifically, the position of the chuck table 8 in the X-axis direction is adjusted by the moving mechanism 10 (see FIGS. 1 and 2) so that the workpiece 11 is not overlapped with the grinding wheel 44 and is disposed in front of the grinding wheel 44 (the left side of the paper surface in FIG. 3). Also, the position of the grinding unit 36 in the Z-axis direction is adjusted by the moving mechanism 24 (see FIG. 1) so that the lower surface of the grinding wheel 48 is positioned below the upper surface of the workpiece 11. The difference ΔH in the height position (position in the Z-axis direction) between the upper surface of the workpiece 11 and the lower surface of the grinding wheel 48 at this time corresponds to the target value of the grinding amount of the workpiece 11 (the difference in the thickness of the workpiece 11 before and after grinding).

[0046] Next, while rotating the grinding wheel 44, the chuck table 8 and the grinding unit 36 are relatively moved along the machining feed direction (X-axis direction), and the workpiece 11 is ground from one end side to the other end side by the grinding wheel 48. Specifically, first, by rotating the spindle 40, the grinding wheel 44 is rotated around the rotation axis of the spindle 40. As a result, the plurality of grinding wheels 48 rotate along an annular orbit (moving path), respectively. Note that the rotation speed of the grinding wheel 44 is set, for example, to be 1000 rpm or more and 3000 rpm or less.

[0047] Then, with the grinding wheel 44 rotating and the chuck table 8 not rotating, the chuck table 8 is moved in the X-axis direction at a predetermined speed by the moving mechanism 10 (see FIGS. 1 and 2). As a result, the chuck table 8 and the grinding wheel 44 relatively move at a predetermined machining feed speed along the machining feed direction perpendicular to the rotation axis of the spindle 40 and approach each other. Note that the moving speed (machining feed speed) of the chuck table 8 is set, for example, to be 1 mm / s or more and 20 mm / s or less.

[0048] FIG. 4(A) is a side view showing the grinding unit 36 for grinding one end portion of the workpiece 11. When the chuck table 8 moves and one end portion of the workpiece 11 (the front end portion in the moving direction of the workpiece 11, the right end portion in the paper surface in FIG. 4(A)) reaches the orbit of the grinding wheel 48, one end portion of the workpiece 11 is cut off by the grinding wheel 48.

[0049] FIG. 4(B) is a side view showing the grinding unit 36 for grinding the central portion of the workpiece 11. As the machining feed progresses, the central portion of the workpiece 11 reaches the orbit of the grinding wheel 48 and is cut off by the grinding wheel 48.

[0050] FIG. 4(C) is a side view showing a grinding unit 36 that grinds the other end of the workpiece 11. As the machining feed further progresses, the other end of the workpiece 11 (the rear end in the moving direction of the workpiece 11, the left end of the drawing sheet in FIG. 4(C)) reaches the orbit of the grinding wheel 48 and is cut off by the grinding wheel 48. In this way, the workpiece 11 is ground from one end side to the other end side by the grinding wheel 48, and the entire workpiece 11 is thinned.

[0051] Then, the grinding of the workpiece 11 is repeated until the thickness of the workpiece 11 reaches the target value of the final thickness (finish thickness). Note that the number of times of creep feed grinding (the number of times of performing the grinding step) can be appropriately set according to the material of the workpiece 11, the amount of grinding, etc.

[0052] During the grinding of the workpiece 11, a grinding fluid 50a such as pure water is supplied from the grinding fluid supply unit 50 to the workpiece 11 and the grinding wheel 48. The grinding fluid supply unit 50 is provided so that its length direction is along the Y-axis direction (see FIG. 1), and is provided with a grinding fluid supply port (not shown) that opens toward the front end of the grinding wheel 44.

[0053] For example, the grinding fluid supply unit 50 includes a slit-shaped grinding fluid supply port formed along the length direction of the grinding fluid supply unit 50, or a plurality of circular grinding fluid supply ports arranged at predetermined intervals along the length direction of the grinding fluid supply unit 50. Then, the grinding fluid 50a supplied from the liquid supply source 54 (see FIG. 1) to the grinding fluid supply unit 50 via the valve 52 (see FIG. 1) is jetted in a band shape or a column shape from the grinding fluid supply port toward the front end of the grinding wheel 44. Thereby, the grinding fluid 50a is supplied to the region (processing region) where the workpiece 11 and the grinding wheel 48 come into contact from the outside of the grinding wheel 44, the workpiece 11 and the grinding wheel 48 are cooled, and the chips (processing chips) generated by the grinding process are washed away.

[0054] In creep-feed grinding, the contact area between the workpiece 11 and the plurality of grinding wheels 48 provided on the grinding wheel 44 changes as grinding progresses. FIG. 5 is a plan view showing a disk-shaped workpiece 11 ground by creep-feed grinding.

[0055] In the initial stage of grinding the workpiece 11, the trajectory of the grinding wheel 48 overlaps with the first region 13A corresponding to one end of the workpiece 11, and the first region 13A is ground. At this time, the contact area between the workpiece 11 and the grinding wheel 48 is small. Thereafter, as the machining feed of the chuck table 8 progresses, the contact area between the workpiece 11 and the grinding wheel 48 gradually increases. Then, when the trajectory of the grinding wheel 48 overlaps with the arc-shaped second region 13B of the workpiece 11, the contact area between the workpiece 11 and the grinding wheel 48 becomes maximum.

[0056] Thereafter, as the machining feed of the chuck table 8 further progresses, the contact area between the workpiece 11 and the grinding wheel 48 gradually decreases. Then, in the final stage of grinding the workpiece 11, the trajectory of the grinding wheel 48 overlaps with the third region 13C corresponding to the other end of the workpiece 11, and the third region 13C is ground.

[0057] Here, if the amount of the grinding fluid 50a supplied to the contact area (machining area) between the workpiece 11 and the grinding wheel 48 is insufficient, the sufficient grinding fluid 50a will not reach the entire machining area. As a result, the cooling of the workpiece 11 and the grinding wheel 48 and the removal of machining chips become insufficient, and machining defects are likely to occur. On the other hand, if the supply amount of the grinding fluid 50a is set based on the contact area (maximum contact area) between the workpiece 11 and the grinding wheel 48 when the grinding wheel 48 overlaps with the second region 13B of the workpiece 11, an excessive amount of the grinding fluid 50a that does not contribute to the cooling of the workpiece 11 and the grinding wheel 48 and the removal of machining chips will be supplied during the grinding of the first region 13A and the third region 13C of the workpiece 11.

[0058] Therefore, in the present embodiment, the flow rate of the grinding fluid 50a is adjusted so that the larger the contact area between the workpiece 11 and the grinding wheel 48, the larger the amount of the grinding fluid 50a supplied to the machining area. Thereby, an appropriate amount of the grinding fluid 50a corresponding to the contact area between the workpiece 11 and the grinding wheel 48 is supplied, and the consumption amount of the grinding fluid 50a can be reduced while suppressing the occurrence of machining defects.

[0059] As shown in FIG. 1, the control unit 56 includes a flow rate information storage unit 56a that stores information (flow rate information) indicating the flow rate of the grinding fluid 50a corresponding to the contact area between the workpiece 11 and the grinding wheel 48, and a flow rate adjustment unit 56b that adjusts the flow rate of the grinding fluid 50a supplied to the machining area based on the flow rate information stored in the flow rate information storage unit 56a.

[0060] The flow rate information stored in the flow rate information storage unit 56a indicates the flow rate of the grinding fluid 50a set so that the larger the contact area between the workpiece 11 and the grinding wheel 48, the larger the amount of the grinding fluid 50a supplied to the machining area. For example, the flow rate information including information indicating the position of the chuck table 8 (position information of the chuck table 8) and the flow rate of the grinding fluid 50a corresponding to the position information of the chuck table 8 is stored in the flow rate information storage unit 56a.

[0061] Specifically, the contact area between the workpiece 11 and the grinding wheel 48 depends on the position of the chuck table 8 in the machining feed direction (X-axis direction) during the grinding process. Also, the appropriate flow rate of the grinding fluid 50a depends on the contact area between the workpiece 11 and the grinding wheel 48. Therefore, the grinding apparatus 2 is operated experimentally in advance to specify the appropriate flow rate of the grinding fluid 50a to be supplied to the grinding fluid supply unit 50 for each position of the chuck table 8. Then, the correspondence relationship between the position information of the chuck table 8 and the desired flow rate of the grinding fluid 50a is stored in the flow rate information storage unit 56a as the flow rate information.

[0062] For example, data (table) including the position of the chuck table 8 and the flow rate of the grinding fluid 50a to be supplied to the grinding fluid supply unit 50 when the chuck table 8 is disposed at that position is used as the flow rate information. Also, a function for calculating the desired flow rate of the grinding fluid 50a based on the position of the chuck table 8 may be used as the flow rate information.

[0063] The position information of the chuck table 8 is not limited as long as it is a value that directly or indirectly indicates the position of the chuck table 8. For example, as the position information, the coordinates of the chuck table 8 or the moving plate 12 (see FIG. 2) or the number of rotations of the pulse motor 18 (see FIG. 2) can be used. Also, the moving distance from the initial position of the chuck table 8, the moving time of the chuck table 8, etc. can be used as the position information of the chuck table 8.

[0064] During the grinding of the workpiece 11, the position information of the chuck table 8 is sequentially input from an arbitrary component of the grinding apparatus 2 to the flow rate adjustment unit 56b. For example, the coordinates of the chuck table 8 or the moving plate 12 or the number of rotations of the pulse motor 18 are input from the moving mechanism 10 (see FIG. 2) to the flow rate adjustment unit 56b. Then, the flow rate adjustment unit 56b determines the flow rate of the grinding fluid iced to be supplied to the grinding fluid supply unit 50 by applying the input position information of the chuck table 8 to the flow rate information stored in the flow rate information storage unit 56a.

[0065] Thereafter, the flow rate adjustment unit 56b outputs a control signal to the valve 52 to adjust the opening / closing or the opening degree of the valve 52. As a result, the grinding fluid 50a is supplied from the liquid supply source 54 to the grinding fluid supply unit 50 at the flow rate determined by the flow rate information storage unit 56a. As a result, an amount of the grinding fluid 50a corresponding to the contact area between the workpiece 11 and the grinding wheel 48 is supplied to the area (processing area) where the workpiece 11 and the grinding wheel 48 are in contact with each other.

[0066] In addition, when it is possible to measure the contact area between the workpiece 11 and the grinding wheel 48, flow rate information (table, function, etc.) including the contact area and the flow rate of the grinding fluid 50a corresponding to the contact area may be stored in the flow rate information storage unit 56a. In this case, during the grinding of the workpiece 11, the contact area between the workpiece 11 and the grinding wheel 48 is sequentially measured. Then, the flow rate adjustment unit 56b determines the flow rate of the grinding fluid 50a to be supplied to the grinding fluid supply unit 50 by applying the measured contact area to the flow rate information stored in the flow rate information storage unit 56a. Thereby, the flow rate of the grinding fluid 50a can be adjusted according to the actual contact area between the workpiece 11 and the grinding wheel 48.

[0067] When the above grinding apparatus 2 is used, in the grinding step, the flow rate of the grinding fluid 50a is adjusted so that the larger the contact area between the workpiece 11 and the grinding wheel 48, the larger the amount of the grinding fluid 50a supplied to the machining area. Specifically, when one end of the workpiece 11 is being ground, the flow rate of the grinding fluid 50a is small (see Fig. 4(A)), and a small amount of the grinding fluid 50a is supplied to the machining area. Then, as the machining feed progresses, the contact area between the workpiece 11 and the grinding wheel 48 increases, and the flow rate of the grinding fluid 50a also increases (see Fig. 4(B)). After that, as the machining feed further progresses, the contact area between the workpiece 11 and the grinding wheel 48 decreases, and the flow rate of the grinding fluid 50a also decreases (see Fig. 4(C)).

[0068] As described above, the grinding apparatus 2 according to the present embodiment can adjust the flow rate of the grinding fluid 50a so that the larger the contact area between the workpiece 11 and the grinding wheel 48, the larger the amount of the grinding fluid 50a supplied to the machining area. Thereby, the grinding fluid 50a can be supplied to the machining area at an appropriate flow rate according to the contact area between the workpiece 11 and the grinding wheel 48, and it becomes possible to reduce the consumption amount of the grinding fluid 50a while suppressing the occurrence of machining defects.

[0069] In the above-described embodiment, an example in which a disk-shaped workpiece 11 (see FIG. 5) is ground has been described, but the shape of the workpiece is not limited. For example, a rectangular workpiece can also be ground by the grinding apparatus 2. Also in this case, the flow rate of the grinding fluid 50a is adjusted according to the contact area between the workpiece and the grinding wheel 48.

[0070] FIG. 6(A) is a plan view showing a rectangular workpiece 15. The workpiece 15 is a plate-shaped substrate formed in a rectangular shape in plan view, and is disposed on the chuck table 8 (see FIG. 1 etc.) such that the short side is along the machining feed direction (X-axis direction). When creep feed grinding is performed on the workpiece 15 in this state, a first region 17A corresponding to one end portion in the machining feed direction (one end portion in the short side direction), an arc-shaped second region 17B, and a pair of third regions 17C corresponding to the other end portion in the machining feed direction (the other end portion in the short side direction) are ground in order.

[0071] FIG. 6(B) is a plan view showing a square workpiece 19. The workpiece 19 is a plate-shaped substrate formed in a square shape in plan view, and one piece is disposed on the chuck table 8 (see FIG. 1 etc.) such that it is along the machining feed direction (X-axis direction). When creep feed grinding is performed on the workpiece 19 in this state, a first region 21A corresponding to one end portion in the machining feed direction, an arc-shaped second region 21B, and a pair of third regions 21C corresponding to the other end portion in the machining feed direction are ground in order.

[0072] As shown in FIGS. 6(A) and 6(B), also when creep feed grinding is performed on a rectangular workpiece, the contact area between the workpiece and the grinding wheel 48 increases and decreases. Then, by adjusting the flow rate of the grinding fluid 50a with the control unit 56 (see FIG. 1), an appropriate amount of the grinding fluid 50a corresponding to the contact area between the workpiece and the grinding wheel 48 is supplied to the machining region. Note that the shape of the holding surface 8a (see FIG. 1 etc.) of the chuck table 8 can be appropriately changed according to the shape of the workpiece.

[0073] In addition, the structure, method, etc. according to the above-described embodiment can be appropriately changed and implemented without departing from the scope of the object of the present invention.

Description of Reference Numerals

[0074] 11 Workpiece 11a Surface (first surface) 11b Back surface (second surface) 13A First region 13B Second region 13C Third region 15 Workpiece 17A First region 17B Second region 17C Third region 19 Workpiece 21A First region 21B Second region 21C Third region 2 Grinding device 4 Base 4a Opening 6 Support structure 8 Chuck table (holding table) 8a Holding surface 10 Moving mechanism (moving unit) 12 Moving plate 14 Nut part 16 Ball screw 18 Pulse motor 20 Table cover 22 Dust and splash proof cover 24 Moving mechanism (moving unit) 26 Guide rail 28 Moving plate 30 Ball screw 32 Pulse motor 34 Support member 36 Grinding unit 38 Housing 40 Spindle 42 Mount 44 Grinding wheel 46 Wheel base 48 Grinding stone 50 Grinding fluid supply unit 50a Grinding fluid 52 Valve 54 Liquid supply source 56 Control Unit (Control Section, Control Device) 56a Flow Rate Information Storage Section 56b Flow Rate Adjustment Section

Claims

1. A grinding apparatus for grinding a workpiece, comprising: a chuck table having a holding surface for holding the workpiece; a grinding unit having a spindle to which a grinding wheel including a grinding stone is attached at its tip; a moving mechanism for relatively moving the chuck table and the grinding unit along a direction perpendicular to the rotation axis of the spindle; a grinding fluid supply unit for supplying grinding fluid from the outside of the grinding wheel to a machining area where the workpiece and the grinding stone come into contact; a control unit, wherein the control unit includes a flow rate information storage unit that stores flow rate information indicating a flow rate of the grinding fluid set such that the amount of the grinding fluid supplied to the machining area increases as the contact area between the workpiece and the grinding stone increases; and a flow rate adjustment unit that adjusts the flow rate of the grinding fluid supplied to the machining area based on the flow rate information stored in the flow rate information storage unit, wherein the flow rate information includes position information of the chuck table or the contact area, and the flow rate of the grinding fluid corresponding to the position information or the contact area. The grinding apparatus is characterized by this.

2. A method for grinding a workpiece using a grinding apparatus, the grinding apparatus comprising a chuck table having a holding surface for holding the workpiece and a grinding unit having a spindle to which a grinding wheel including a grinding stone is attached at its tip, the method comprising: a holding step of holding the workpiece by the chuck table; a grinding step of relatively moving the chuck table and the grinding unit along a direction perpendicular to the rotation axis of the spindle while supplying grinding fluid from the outside of the grinding wheel to a machining area where the workpiece and the grinding stone come into contact, and grinding the workpiece with the grinding stone, wherein in the grinding step, based on flow rate information including position information of the chuck table or the contact area between the workpiece and the grinding stone and the flow rate of the grinding fluid corresponding to the position information or the contact area, the flow rate of the grinding fluid is adjusted such that the amount of the grinding fluid supplied to the machining area increases as the contact area increases. The method for grinding a workpiece is characterized by this. ​

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