Chuck table, grinding device, and grinding method for a workpiece

Abstract

The present invention provides a chuck table, a grinding device, and a grinding method of a workpiece. When performing a creep feed grinding in a state where a plurality of holding surfaces of the chuck table respectively hold workpieces, double grinding of a specific workpiece is prevented. The plurality of holding surfaces of the chuck table are arranged such that the heights from a reference surface are ascending along a first direction parallel to the holding surfaces. Therefore, in a case where the chuck table is used, it is possible to perform a creep feed grinding on the workpieces respectively held by the plurality of holding surfaces in a state where a grinding unit is positioned at different heights. In this case, the workpiece on which the creep feed grinding has been performed is located lower from the grinding unit when other workpieces are ground. Thus, in the creep feed grinding, it is possible to prevent double grinding of a specific workpiece.

Description

Technical Field

[0001] The present invention relates to a chuck table that holds a workpiece using multiple holding surfaces, a grinding apparatus having the chuck table, and a grinding method for grinding a workpiece using the grinding apparatus. Background Technology

[0002] Chips, such as ICs (Integrated Circuits) and LSIs (Large Scale Integration), are indispensable components in various electronic devices, including mobile phones and personal computers. Such chips are manufactured, for example, by dividing a wafer with a large number of devices formed on its front side into regions containing each device.

[0003] Furthermore, for purposes such as chip miniaturization and weight reduction, the wafer is mostly thinned before dicing. One method for thinning the wafer is grinding based on a grinding apparatus. This grinding apparatus, for example, includes: a chuck stage having a holding surface for holding the wafer; and a grinding unit disposed above the chuck stage and having a spindle capable of loading and unloading grinding wheels with multiple grinding tools discretely arranged in a ring at its lower end.

[0004] In such grinding apparatuses, wafers are sometimes thinned using a grinding method also known as creep grinding (see, for example, Patent Document 1). In this grinding method, the front side of the wafer is first held on the holding surface of the chuck table. Then, with the grinding unit positioned rearward as viewed from the chuck table, the lower surfaces of multiple grinding tools are positioned at a height between the back (upper) and front (lower) surfaces of the wafer.

[0005] Furthermore, while the chuck table and grinding unit are moved relative to each other in the front-back direction, multiple grinding tools located on the front side of the rotating grinding wheel are brought into contact with the upper surface (back side) of the wafer held by the chuck table from the rear side. Thus, the multiple grinding tools grind from the rear end to the front end of the wafer from the upper surface (back side). As a result, the wafer is thinned to a predetermined finishing thickness.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2005-28550

[0007] Grinding equipment is used not only for thinning disc-shaped wafers, but also for thinning rectangular package substrates such as CSP (Chip Size Package) substrates or QFN (Quad Flat Non-leaded package) substrates. Grinding equipment used for grinding such substrates typically has a chuck stage arranged with multiple parallel holding surfaces of the same shape (e.g., rectangular) arranged in the front-to-back direction.

[0008] Furthermore, when the workpieces are held in place by the multiple holding surfaces during creep grinding, grinding is performed sequentially starting from the rearmost workpiece among the multiple workpieces. As a result, the multiple workpieces are each thinned to a predetermined finishing thickness.

[0009] However, in cases where multiple workpieces are thinned in this way, sometimes only the workpiece located at the rear of the multiple workpieces is ground twice. Specifically, sometimes the workpiece is first ground by multiple grinding tools located in front of the rotating grinding wheel, and then ground again by multiple grinding tools located behind the rotating grinding wheel.

[0010] In this situation, deviations may occur in the thickness of multiple workpieces after grinding. In addition, unexpected saw marks may form on the upper surface of the rearmost workpiece among the multiple workpieces, resulting in scratches or cracks on that workpiece. Summary of the Invention

[0011] In view of this, the object of the present invention is to prevent a specific workpiece from being ground twice when the workpiece is held in a state where multiple holding surfaces of the chuck table are used to hold the workpiece.

[0012] According to one aspect of the invention, a chuck table is provided, comprising: a first holding surface and a second holding surface, the first holding surface and the second holding surface being parallel to each other and having the same shape; and a reference surface, which is parallel to the first holding surface and the second holding surface and surrounds the first holding surface and the second holding surface in a top view, the chuck table holding a workpiece using the first holding surface and the second holding surface respectively, wherein the first holding surface and the second holding surface are configured such that their heights from the reference surface ascend along a first direction parallel to the first holding surface and the second holding surface.

[0013] According to another aspect of the invention, a grinding apparatus is provided, comprising: the aforementioned chuck table; a grinding unit having a spindle with a plurality of grinding wheels arranged in a ring at its front end; a first moving mechanism for moving the chuck table and the grinding unit relative to each other along a first direction parallel to the reference surface and the first and second holding surfaces; and a second moving mechanism for moving the chuck table and the grinding unit relative to each other along a second direction perpendicular to the reference surface and the first and second holding surfaces.

[0014] According to another aspect of the present invention, a grinding method for a workpiece is provided, wherein the workpiece is ground using the aforementioned grinding apparatus, the grinding method comprising the following steps: a holding step, wherein the workpiece is held on a first holding surface and a second holding surface respectively; and a grinding step, wherein after the holding step, the chuck table and the grinding unit are moved relative to each other along a first direction, and the distance between the reference surface and the plurality of grinding tools along the second direction is progressively increased in such a manner that the workpiece held by the first holding surface and the second holding surface respectively reaches a predetermined finished thickness, while the rotating plurality of grinding tools are brought into contact with the workpiece held by the first holding surface and the second holding surface respectively, thereby grinding the workpiece.

[0015] According to another aspect of the invention, a method for grinding a workpiece is provided, wherein the workpiece is ground using a grinding apparatus comprising: a chuck table including: a first retaining surface and a second retaining surface, the first retaining surface and the second retaining surface being parallel to each other and having the same shape; and a reference surface parallel to the first retaining surface and the second retaining surface, and surrounding the first retaining surface and the second retaining surface in a top view, the chuck table holding the workpiece using the first retaining surface and the second retaining surface respectively; and a grinding unit having a spindle at its front end for mounting a grinding wheel or workpiece for the chuck table. The workpiece grinding wheel has multiple grinding wheels arranged in a ring around the chuck table, and multiple grinding wheels arranged in a ring around the workpiece. A first moving mechanism moves the chuck table and the grinding unit relative to each other along a first direction parallel to a reference surface, a first holding surface, and a second holding surface. A second moving mechanism moves the chuck table and the grinding unit relative to each other along a second direction perpendicular to the reference surface, the first holding surface, and the second holding surface. The workpiece grinding method includes the following steps: holding surface grinding. The steps involve moving the chuck table and the grinding unit, on which the grinding wheels for the chuck table are mounted at the front end of the spindle, relative to each other along the first direction. While progressively increasing the distance along the second direction between the reference surface and the plurality of grinding wheels for the chuck table, the rotating grinding wheels for the chuck table contact the chuck table, thereby grinding the chuck table. The holding step involves grinding the first and second holding surfaces on the first and second holding surfaces respectively, after the holding surface grinding step. The workpiece is held in place; and a grinding step is performed, after which the chuck table and the grinding unit, on which the grinding wheel for the workpiece is mounted at the front end of the spindle, are moved relative to each other along the first direction, and while the distance between the reference surface and the plurality of grinding tools for the workpiece along the second direction is progressively increased in such a way that the workpiece held by the first holding surface and the second holding surface respectively reaches a predetermined finished thickness, the plurality of grinding tools for the workpiece are brought into contact with the workpiece held by the first holding surface and the second holding surface respectively, thereby grinding the workpiece.

[0016] In the chuck table of the present invention, the first holding surface and the second holding surface are configured such that their heights from the reference surface increase sequentially along a first direction parallel to the first holding surface and the second holding surface. Therefore, when using this chuck table, it is possible to perform slow-feed grinding on workpieces held by the first holding surface and the second holding surface respectively while the grinding unit is positioned at different heights.

[0017] In this case, the workpiece that has already undergone creep-feed grinding is positioned below when other workpieces are being ground, as viewed from the grinding unit. Therefore, in this creep-feed grinding, it is possible to prevent a particular workpiece from being ground twice. Attached Figure Description

[0018] Figure 1 (A) is a schematic top view illustrating an example of a chuck table. Figure 1 (B) is a side view schematically showing an example of a chuck worktable.

[0019] Figure 2 It is a schematic illustration of having Figure 1 (A) and Figure 1 (B) is a partial sectional side view of an example of a grinding apparatus with a chuck table.

[0020] Figure 3 This is an illustrative representation of the use. Figure 2 A flowchart illustrating an example of a grinding method for grinding a workpiece using the grinding apparatus shown.

[0021] Figure 4 (A) is a side view schematically illustrating the holding step. Figure 4 (B) and Figure 4 (C) is a side view schematically showing the grinding process.

[0022] Figure 5 (A) Figure 5 (B) and Figure 5 (C) is a side view schematically showing the grinding process.

[0023] Figure 6 (A) Figure 6 (B) and Figure 6 (C) is a side view schematically showing the grinding process.

[0024] Figure 7 This is a flowchart schematically illustrating a variation of a grinding method for a workpiece.

[0025] Figure 8 (A) Figure 8 (B) and Figure 8 (C) is a side view schematically showing the situation of holding the face grinding step.

[0026] Figure 9 (A) Figure 9 (B) and Figure 9 (C) is a side view schematically showing the situation of holding the face grinding step.

[0027] Label Explanation

[0028] 2: Chuck worktable; 4: Base (4a: upper surface (datum surface)); 6: Holding part (6a: frame, 6b: perforated plate, 6c: upper surface (holding surface)); 8: Holding part (8a: frame, 8b: perforated plate, 8c: upper surface (holding surface)); 10: Holding part (10a: frame, 10b: perforated plate, 10c: upper surface (holding surface)); 12: Holding part (12a: frame, 12b: perforated plate, 12c: upper surface (holding surface)); 14: Grinding device; 16: Base (16a: opening); 18: X-axis moving mechanism (First moving mechanism); 20: Lead screw shaft; 22: Motor; 24: Nut part; 26: Support structure; 28: Z-axis moving mechanism (second moving mechanism); 30: Guide rail; 32: Moving plate; 34: Lead screw shaft; 36: Motor; 38: Nut part; 40: Grinding unit; 42: Support component; 44: Housing; 46: Connecting component; 48: Spindle; 50: Mounting base; 52: Grinding wheel (52a: Grinding wheel for chuck table); 54 (54a): Grinding wheel base; 56: Grinding tool (56a: Grinding tool for chuck table). Detailed Implementation

[0029] The embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 (A) is a schematic top view illustrating an example of a chuck table. Figure 1 (B) is a side view schematically showing an example of a chuck worktable. Figure 1 (A) and Figure 1 The chuck worktable 2 shown in (B) has, for example, a disc-shaped base portion 4 formed of ceramic or the like.

[0030] The base portion 4 has a flat upper surface (reference surface) 4a. Furthermore, on the reference surface 4a, a plurality of cuboid-shaped retaining portions 6, 8, 10, and 12 are provided in a manner that are arranged side by side along a first direction (D1) parallel to the reference surface 4a and protrude along a second direction (D2) perpendicular to the reference surface 4a.

[0031] Multiple retaining parts 6, 8, 10, and 12 each have a cuboid frame 6a, 8a, 10a, and 12a made of ceramic or the like, and a recess is formed in the upper part of each frame 6a, 8a, 10a, and 12a. A cuboid perforated plate 6b, 8b, 10b, and 12b made of ceramic or the like is fixed in the recess.

[0032] Furthermore, the perforated plates 6b, 8b, 10b, and 12b have an upper surface parallel to the reference plane 4a. Additionally, each of the base portion 4 and the plurality of holding portions 6, 8, 10, and 12 has an attraction path provided inside for communicating the lower surface side of the perforated plates 6b, 8b, 10b, and 12b with an attraction source such as an injector.

[0033] Furthermore, when the suction source is activated while the suction path is connected to the suction source, a negative pressure is generated in the space near the upper surfaces of the porous plates 6b, 8b, 10b, and 12b. Therefore, in each of the plurality of holding parts 6, 8, 10, and 12, their upper surfaces 6c, 8c, 10c, and 12c function as holding surfaces for holding the workpiece.

[0034] Furthermore, the reference surface 4a of the base portion 4 is configured to surround the upper surfaces (holding surfaces) 6c, 8c, 10c, and 12c of the holding portions 6, 8, 10, and 12 in the top view. In addition, the multiple holding surfaces 6c, 8c, 10c, and 12c are parallel to the reference surface 4a.

[0035] Furthermore, the multiple retaining surfaces 6c, 8c, 10c, and 12c have the same shape. Specifically, each of the multiple retaining surfaces 6c, 8c, 10c, and 12c is a rectangle with a pair of short sides extending along the first direction and a pair of long sides extending along a third direction (D3) perpendicular to the first and second directions.

[0036] However, the heights of the multiple retaining surfaces 6c, 8c, 10c, and 12c from the reference surface 4a are different. Specifically, the heights of the multiple retaining surfaces 6c, 8c, 10c, and 12c from the reference surface 4a are in ascending order along the first direction. That is, retaining surface 6c is lower than the other retaining surfaces 8c, 10c, and 12c. In addition, retaining surface 8c is lower than retaining surfaces 10c and 12c. Furthermore, retaining surface 10c is lower than retaining surface 12c.

[0037] Furthermore, the difference in height between a pair of adjacent holding surfaces (e.g., holding surface 6c and holding surface 8c) along the first direction is determined by taking into account the deviation in the thickness of the workpiece held in each of the multiple holding surfaces 6c, 8c, 10c, and 12c. Specifically, this difference is 10 μm or more and 300 μm or less (e.g., 50 μm).

[0038] Figure 2 This is a partial cross-sectional side view schematically illustrating an example of a grinding apparatus with a chuck table 2. Additionally, Figure 2 The X-axis (front-back direction) and Y-axis (left-right direction) shown are perpendicular to each other on the horizontal plane. In addition, the Z-axis (up-down direction) is perpendicular to the X-axis and Y-axis (vertical direction).

[0039] Figure 2 The grinding apparatus 14 shown has a base 16 that supports or houses the various components. A cuboid opening 16a is provided on the upper surface of the base 16. Furthermore, an X-axis moving mechanism (first moving mechanism) 18 is provided inside the opening 16a. This X-axis moving mechanism 18 has a lead screw 20 extending along the X-axis direction.

[0040] A motor 22 for rotating the lead screw shaft 20 is connected to one end of the lead screw shaft 20. In addition, a nut part 24 is provided on the surface of the lead screw shaft 20 with a helical groove to hold the balls rolling on the surface of the rotating lead screw shaft 20, thus forming a ball screw.

[0041] That is, when the lead screw 20 rotates, the balls circulate within the nut portion 24, and the nut portion 24 moves along the X-axis. Furthermore, the lower part of the chuck table 2 is mounted on the upper part of the nut portion 24 in a manner parallel to the X-axis, Z-axis, and Y-axis directions respectively, according to the first direction (D1), second direction (D2), and third direction (D3). Therefore, if the lead screw 20 is rotated using the motor 22, the chuck table 2 and the nut portion 24 move together along the X-axis.

[0042] Furthermore, the grinding apparatus 14 has a built-in suction source (not shown), which is connected via a valve (not shown) to suction paths provided inside the base portion 4 and each of the plurality of holding portions 6, 8, 10, and 12. Therefore, when the suction source is activated, opening the valve allows the workpiece to be held on the holding surfaces 6c, 8c, 10c, and 12c of the plurality of holding portions 6, 8, 10, and 12.

[0043] Behind the chuck table 2 and the X-axis moving mechanism 18 ( Figure 2 A cuboid support structure 26 is provided on the right side of the paper. Furthermore, a Z-axis moving mechanism (second moving mechanism) 28 is provided on the front surface of the support structure 26. This Z-axis moving mechanism 28 is connected to the grinding unit 40, which will be described later, so that the grinding unit 40 can move along the Z-axis direction.

[0044] The Z-axis moving mechanism 28 has a pair of guide rails 30 fixed to the front side of the support structure 26 and extending along the Z-axis direction. A moving plate 32 is connected to the front surface side of the pair of guide rails 30 in a manner that allows it to slide along the pair of guide rails 30.

[0045] A lead screw shaft 34 extending along the Z-axis is disposed between a pair of guide rails 30. A motor 36 for rotating the lead screw shaft 34 is connected to one end of the lead screw shaft 34. In addition, a nut portion 38 is provided on the surface of the lead screw shaft 34 with a helical groove to accommodate the balls rolling on the surface of the rotating lead screw shaft 34, thus forming a ball screw.

[0046] That is, when the lead screw shaft 34 rotates, the balls circulate within the nut portion 38, and the nut portion 38 moves along the Z-axis. Furthermore, the nut portion 38 is fixed to the back (rear surface) side of the moving plate 32. Therefore, if the lead screw shaft 34 is rotated using the motor 36, the moving plate 32 and the nut portion 38 move together along the Z-axis.

[0047] A grinding unit 40 is provided on the front (front surface) side of the movable plate 32. The grinding unit 40 has a hollow cylindrical support member 42 fixed to the front side of the movable plate 32. A hollow cylindrical housing 44 is housed in the support member 42. The housing 44 is fixed to the bottom wall of the support member 42 by means of a connecting member 46 provided on the lower surface.

[0048] A cylindrical spindle 48 extending along the Z-axis is rotatably housed within the housing 44. The front end (lower end) of the spindle 48 protrudes from the housing 44 and extends downward from the bottom surface of the support member 42 through an opening provided in the bottom wall of the support member 42. Furthermore, a disc-shaped mounting base 50 made of metal or the like is fixed to the front end of the spindle 48.

[0049] The diameter of the mounting base 50 is shorter than the diameter of the chuck table 2 (the diameter of the reference surface 4a of the base portion 4). Figure 2 The image shows a mounting base 50 with a diameter approximately half that of the chuck table 2. Additionally, an annular grinding wheel 52 is mounted on the lower surface of the mounting base 50 in a removable manner.

[0050] The grinding wheel 52, for example, has an annular grinding wheel base 54 formed of a metal such as aluminum or stainless steel, the outer diameter of which is approximately equal to the diameter of the mounting base 50. That is, in Figure 2 The image shows a grinding wheel base 54 with a diameter approximately half that of the chuck table 2.

[0051] Furthermore, the upper surface of the grinding wheel base 54 is fixed to the lower surface of the mounting base 50 by bolts or other fasteners. Additionally, a plurality of grinding tools 56 are fixed to the lower surface of the grinding wheel base 54 in a ring-like discrete arrangement. These grinding tools 56, for example, each have a cuboid shape and are arranged at approximately equal intervals along the circumference of the grinding wheel base 54.

[0052] The grinding wheel 56 is formed by fixing abrasive grains made of diamond or cBN (cubic boron nitride) using a bonding material formed by a metal bond, resin bond, or ceramic bond. However, there are no restrictions on the material, shape, structure, or size of the grinding wheel 56. In addition, the number of multiple grinding wheels 56 can be arbitrarily set.

[0053] Additionally, a rotary drive source (not shown) for rotating the spindle 48 is connected to the base (upper) end of the spindle 48. When the rotary drive source causes the spindle 48 to rotate along the rotation axis in the Z-axis direction, the mounting base 50 and the grinding wheel 52 (grinding wheel base 54 and multiple grinding tools 56) rotate together with the spindle 48.

[0054] Figure 3 This is a flowchart schematically illustrating an example of a grinding method for grinding a workpiece using a grinding apparatus 14. In this method, the workpiece is first held on multiple holding surfaces 6c, 8c, 10c, and 12c of the chuck table 2 (holding step: S1). Figure 4 (A) is a side view schematically showing the situation of holding step (S1).

[0055] In this holding step (S1), the X-axis moving mechanism 18 is first activated so as to position the workpieces 11 at multiple holding surfaces 6c, 8c, 10c, and 12c of the chuck table 2 (e.g., away from the grinding unit 40). Then, the multiple workpieces 11 are respectively moved into the multiple holding surfaces 6c, 8c, 10c, and 12c of the chuck table 2.

[0056] Furthermore, the workpiece 11 is, for example, a cuboid packaging substrate such as a CSP substrate or a QFN substrate, whose upper and lower surface shapes are approximately the same as the shapes of the plurality of holding surfaces 6c, 8c, 10c, and 12c. Next, with the suction source, which is connected to the suction path provided inside the chuck stage 2 via a valve or the like, in operation, the valve is opened. Thus, the holding step (S1) is completed.

[0057] exist Figure 3 In the workpiece grinding method shown, after the holding step (S1), the workpiece 11, which is held by multiple holding surfaces 6c, 8c, 10c, and 12c respectively, is subjected to slow feed grinding (grinding step: S2) while the grinding unit 40 is positioned at different heights.

[0058] Specifically, in the grinding step (S2), the chuck table 2 is moved along the X-axis direction (first direction), and while the workpiece 11 held by the multiple holding surfaces 6c, 8c, 10c, and 12c is progressively expanded in such a way that the workpiece 11 is held by the multiple holding surfaces 6c, 8c, 10c, and 12c to a specified finished thickness, the interval between the reference surface 4a and the multiple grinding tools 56 along the Z-axis direction (second direction) is increased in stages, and the multiple rotating grinding tools 56 are brought into contact with the workpiece 11 held by the multiple holding surfaces 6c, 8c, 10c, and 12c, thereby grinding the workpiece 11.

[0059] Figure 4 (B) Figure 4 (C) Figure 5 (A) Figure 5 (B) Figure 5 (C) Figure 6 (A) Figure 6 (B) and Figure 6 (C) is a side view schematically illustrating the grinding step (S2). In this grinding step (S2), the grinding unit 40 is first lowered via the Z-axis moving mechanism 28 in such a manner that the lower surfaces of the plurality of grinding tools 56 of the grinding wheel 52 are positioned above the finished thickness of the workpiece 11 above the holding surface 6c (see reference). Figure 4 (B)

[0060] Next, while moving the chuck table 2 rearward along the X-axis, the plurality of grinding tools 56 located in front of the rotating grinding wheel 52 come into contact with the upper surface of the workpiece 11 held by the holding surface 6c. As a result, grinding is performed from the rear end to the front end of the upper surface of the workpiece 11 held by the holding surface 6c, thinning the workpiece 11 to a predetermined finished thickness (see reference). Figure 4 (C)).

[0061] Next, the grinding unit 40 is raised via the Z-axis moving mechanism 28 in such a manner that the lower surfaces of the plurality of grinding tools 56 of the grinding wheel 52 are positioned at a position higher than the finished thickness of the workpiece 11 than the holding surface 8c (see reference). Figure 5 (A)).

[0062] Next, while moving the chuck table 2 rearward along the X-axis, the plurality of grinding wheels 56 located in front of the rotating grinding wheel 52 come into contact with the upper surface of the workpiece 11 held by the holding surface 8c. As a result, grinding is performed from the rear end to the front end of the upper surface of the workpiece 11 held by the holding surface 8c, thinning the workpiece 11 to a predetermined finished thickness (see reference). Figure 5 (B)

[0063] At this time, the multiple grinding tools 56 located behind the rotating grinding wheel 52 are positioned above the workpiece 11 held by the holding surface 6c and do not contact the workpiece 11. That is, the workpiece 11 held by the holding surface 6c will not be ground again by the multiple grinding tools 56.

[0064] Next, the grinding unit 40 is raised via the Z-axis moving mechanism 28 in such a manner that the lower surfaces of the plurality of grinding tools 56 of the grinding wheel 52 are positioned at a position higher than the finished thickness of the workpiece 11 than the holding surface 10c (see reference). Figure 5 (C)).

[0065] Next, while moving the chuck table 2 rearward along the X-axis, the plurality of grinding wheels 56 located in front of the rotating grinding wheel 52 come into contact with the upper surface of the workpiece 11 held by the holding surface 10c. As a result, grinding is performed from the rear end to the front end of the upper surface of the workpiece 11 held by the holding surface 10c, thinning the workpiece 11 to a predetermined finished thickness (see reference). Figure 6 (A)).

[0066] At this time, the multiple grinding tools 56 located behind the rotating grinding wheel 52 are positioned above the workpiece 11 held by the holding surface 8c and do not contact the workpiece 11. That is, the workpiece 11 held by the holding surface 8c will not be ground again by the multiple grinding tools 56.

[0067] Next, the grinding unit 40 is raised via the Z-axis moving mechanism 28 in such a manner that the lower surfaces of the plurality of grinding tools 56 of the grinding wheel 52 are positioned at a position higher than the finished thickness of the workpiece 11 than the holding surface 12c (see reference). Figure 6 (B)

[0068] Next, while moving the chuck table 2 rearward along the X-axis, the plurality of grinding wheels 56 located in front of the rotating grinding wheel 52 come into contact with the upper surface of the workpiece 11 held by the holding surface 12c. As a result, grinding is performed from the rear end to the front end of the upper surface of the workpiece 11 held by the holding surface 12c, thinning the workpiece 11 to a predetermined finished thickness (see reference). Figure 6 (C)).

[0069] At this time, the multiple grinding tools 56 located behind the rotating grinding wheel 52 are positioned above the workpiece 11 held by the holding surface 10c and do not contact the workpiece 11. That is, the workpiece 11 held by the holding surface 10c will not be ground again by the multiple grinding tools 56. Thus, the grinding step (S2) is completed.

[0070] The chuck table 2 has multiple holding surfaces 6c, 8c, 10c, and 12c, which are arranged such that their heights from the reference surface 4a increase sequentially along a first direction parallel to them. Therefore, when using the chuck table 2, the workpiece 11 held by the multiple holding surfaces 6c, 8c, 10c, and 12c can be subjected to slow-feed grinding with the grinding unit 40 positioned at different heights.

[0071] In this case, the workpiece 11 that has undergone feed grinding (e.g., the workpiece 11 held by the holding surface 6c) is positioned below when other workpieces 11 (e.g., the workpiece 11 held by the holding surface 8c) are being ground, as viewed from the grinding unit 40. Thus, in this feed grinding, it is possible to prevent a particular workpiece 11 from being ground twice.

[0072] Furthermore, in the grinding method for the workpiece of the present invention, the chuck table 2 can be machined in the grinding apparatus 14 before the aforementioned holding step (S1), in an ascending order of the heights of the plurality of holding surfaces of the chuck table 2 from the reference surface 4a along the first direction. Therefore, for example, even if the heights of the upper surfaces of the holding portions 6, 8, and 10 from the reference surface 4a are equal to the heights of the upper surface (holding surface) 12c of the holding portion 12 from the reference surface 4a, the aforementioned grinding step (S2) can still be performed.

[0073] Furthermore, when grinding the chuck table 2, a different type of grinding wheel (chuck table grinding wheel) is typically used compared to the grinding wheel (workpiece grinding wheel) used when grinding the workpiece 11. That is, a chuck table grinding wheel is typically used on the chuck table 2, which is discretely arranged in a ring and contains multiple grinding tools (workpiece grinding tools) of a different type than those included in the workpiece grinding wheel.

[0074] Figure 7 This is a flowchart illustrating an example of a grinding method for machining a workpiece on the chuck table 2 prior to the holding step (S1). In this method, the chuck table 2 is first ground in ascending order along the X-axis direction (first direction) according to the height of the multiple holding surfaces of the chuck table 2 (holding surface grinding step: S3).

[0075] Specifically, in the holding surface grinding step (S3), the chuck table 2 is moved along the X-axis direction (first direction), and while the distance between the reference surface 4a and the multiple chuck table grinding tools along the Z-axis direction (second direction) is progressively increased in the X-axis direction according to the height of the multiple holding surfaces from the reference surface 4a, the multiple rotating chuck table grinding tools are brought into contact with the chuck table 2, thereby grinding the chuck table 2.

[0076] Figure 8 (A) Figure 8 (B) Figure 8 (C) Figure 9 (A) Figure 9 (B) and Figure 9(C) is a side view schematically illustrating the holding surface grinding step (S3). In this holding surface grinding step (S3), the grinding unit 40 is first lowered by the Z-axis moving mechanism 28 in such a way that the lower surfaces of a plurality of chuck table grinding tools 56a, which are arranged in a ring discrete arrangement on the lower surface side of the grinding wheel base 54a of the chuck table grinding wheel 52a, are positioned lower than the holding surface 12c and higher than the reference surface 4a (see reference). Figure 8 (A)).

[0077] Next, while moving the chuck table 2 rearward along the X-axis, the multiple chuck table grinding tools 56a located in front of the rotating chuck table grinding wheel 52a come into contact with the upper surface of the retaining part 6. As a result, grinding is performed from the rear end to the front end of the upper surface of the retaining part 6, transforming the upper surface of the retaining part 6 to a position lower than the retaining surface 12c, thus forming the retaining surface 6c (see reference). Figure 8 (B)

[0078] Next, the grinding unit 40 is raised via the Z-axis moving mechanism 28 in a manner that positions the lower surface of the grinding wheel 56a of the multiple chuck worktables below the holding surface 12c and above the holding surface 6c (see reference). Figure 8 (C)).

[0079] Next, while moving the chuck table 2 rearward along the X-axis, the multiple chuck table grinding tools 56a located in front of the rotating chuck table grinding wheel 52a are brought into contact with the upper surface of the retaining part 8. As a result, grinding is performed from the rear end to the front end of the upper surface of the retaining part 8, transforming the upper surface of the retaining part 8 to a position lower than the retaining surface 12c and higher than the retaining surface 6c, thus forming the retaining surface 8c (see reference). Figure 9 (A)).

[0080] Next, the grinding unit 40 is raised via the Z-axis moving mechanism 28 in a manner that positions the lower surface of the grinding wheel 56a of the multiple chuck worktables below the holding surface 12c and above the holding surface 8c (see reference). Figure 9 (B)

[0081] Next, while moving the chuck table 2 rearward along the X-axis, the plurality of chuck table grinding tools 56a located in front of the rotating chuck table grinding wheel 52a are brought into contact with the upper surface of the retaining part 10. As a result, grinding is performed from the rear end to the front end of the upper surface of the retaining part 10, transforming the upper surface of the retaining part 10 to a position lower than the retaining surface 12c and higher than the retaining surface 8c, thus forming the retaining surface 10c (see reference). Figure 9 (C)).

[0082] The above steps complete the surface grinding step (S3). Figure 7 In the grinding method for the workpiece shown, after the holding surface grinding step (S3), the holding step (S1) and the grinding step (S2) described above are performed sequentially. As a result, in Figure 7 In the grinding method of the workpiece shown, with Figure 3 Similarly, the grinding method shown for the workpiece can prevent the specific workpiece 11 from being ground twice.

[0083] Furthermore, the above description is only one aspect of the present invention, and the present invention is not limited to the above description. For example, in the chuck worktable of the present invention, the shape of the multiple holding surfaces is not limited to rectangles, but can also be circular, elliptical, or polygonal with three or more sides.

[0084] Furthermore, in the chuck table of the present invention, the base portion 4 can be rectangular or elliptical. Additionally, in the chuck table of the present invention, the heights of the multiple holding surfaces included in the plurality of holding surfaces from the reference surface 4a can be the same.

[0085] Specifically, when the diameter of the grinding wheel 52 is relatively long (for example, when the diameter of the grinding wheel 52 is more than 70% and less than 90% of the diameter of the chuck table 2), when grinding the workpiece 11 held on the upper surface (holding surface) of the holding part 8 and / or the holding part 10 using multiple grinding tools 56 located on the front side of the grinding wheel 52, sometimes the multiple grinding tools 56 located on the rear side of the grinding wheel 52 do not reach above the holding part 6.

[0086] In such cases, for example, the upper surfaces (holding surfaces) of the holding portions 6 and 8 can be made to be at the same height from the reference surface 4a. Alternatively, the upper surfaces (holding surfaces) of the holding portions 6, 8, and 10 can be made to be at the same height from the reference surface 4a. That is, in the chuck table of the present invention, the multiple holding surfaces can be classified into lower holding surfaces with equal heights (e.g., the upper surfaces of the holding portions 6 and 8 or the upper surfaces of the holding portions 6, 8, and 10) and holding surfaces higher than the lower holding surfaces (e.g., the upper surfaces of the holding portions 10 and 12 or the upper surface of the holding portion 12).

[0087] Furthermore, in the grinding apparatus of the present invention, the X-axis moving mechanism 18 can be replaced with an X-axis moving mechanism that moves the grinding unit 40 along the X-axis direction. That is, in the grinding apparatus of the present invention, as long as the chuck table 2 and the grinding unit 40 can move relative to each other along the X-axis direction, there is no limitation on the constituent elements for this purpose.

[0088] Similarly, in the grinding apparatus of the present invention, the Z-axis moving mechanism 28 can be replaced with a Z-axis moving mechanism that moves the chuck table 2 along the Z-axis direction. That is, in the grinding apparatus of the present invention, as long as the chuck table 2 and the grinding unit 40 can move relative to each other along the Z-axis direction, there is no limitation on the constituent elements for this purpose.

[0089] Furthermore, in the grinding method for the workpiece of the present invention, the grinding wheel for the chuck table and the grinding wheel for the workpiece can be the same grinding wheel. That is, in the grinding method for the workpiece of the present invention, multiple identical grinding wheels can be used to grind the chuck table 2 and the workpiece 11.

[0090] In addition, the structure and method of the above embodiments can be appropriately modified and implemented as long as they do not depart from the scope of the present invention.

Claims

1. A chuck worktable, comprising: A first retaining portion and a second retaining portion, the first retaining portion having a first retaining surface and the second retaining portion having a second retaining surface, the first retaining surface and the second retaining surface being parallel to each other and having the same shape; and A reference plane, which is parallel to the first retaining surface and the second retaining surface, and surrounds the first retaining surface and the second retaining surface in the top view. The chuck table holds the workpiece using the first retaining surface and the second retaining surface, respectively. Its features are, The first retaining surface and the second retaining surface are configured such that their heights from the reference surface increase sequentially along a first direction parallel to the first retaining surface and the second retaining surface, respectively. The first retaining part is configured such that the height of the first retaining surface above the reference surface is fixed at a first height. The second retaining part is formed such that the height of the second retaining surface above the reference plane is fixed at a second height, and, The second height is greater than the first height, wherein when the second height is greater than the first height, the bottom surface of the first holding part and the bottom surface of the second holding part are located in the same plane, wherein the same plane is parallel to the reference plane. In both top-view and side-view perspectives (perpendicular to the first direction and parallel to the reference plane), there is a gap between the first retaining surface and the second retaining surface.

2. The chuck worktable according to claim 1, wherein, The first retaining surface and the second retaining surface each have a rectangular shape, the rectangular shape having a pair of short sides extending along the first direction and a pair of long sides having a length greater than the length of the short sides and extending along a third direction perpendicular to the first direction and the second direction.

3. The chuck worktable according to claim 1, wherein, The first retaining portion is spaced apart from the second retaining portion along the first direction.

4. A grinding method for a workpiece, comprising grinding the workpiece using a grinding apparatus. This grinding device has the following features: A chuck table includes: a first holding portion and a second holding portion, the first holding portion having a first holding surface and the second holding portion having a second holding surface, the first holding surface and the second holding surface being parallel to each other and having the same shape; and a reference surface parallel to the first holding surface and the second holding surface, and surrounding the first holding surface and the second holding surface in a top view, the chuck table being configured to hold workpieces using the first holding surface and the second holding surface respectively; A grinding unit having a spindle with a grinding wheel having a plurality of grinding tools arranged in a ring at its front end; A first moving mechanism that moves the chuck table relative to the grinding unit along a first direction; and The second moving mechanism moves the grinding unit relative to the chuck table along a second direction perpendicular to the reference plane, the first holding surface, and the second holding surface. The first retaining surface and the second retaining surface are configured such that their heights from the reference surface increase sequentially along a first direction parallel to the first retaining surface and the second retaining surface, wherein, The first retaining portion is configured such that the height of the first retaining surface above the reference plane is fixed at a first height, and the second retaining portion is configured such that the height of the second retaining surface above the reference plane is fixed at a second height, and the second height is greater than the first height. When the second height is greater than the first height, the bottom surface of the first retaining portion and the bottom surface of the second retaining portion are located on the same plane, which is parallel to the reference plane. In both top-view and side-view perspectives (perpendicular to the first direction and parallel to the reference plane), a gap exists between the first retaining surface and the second retaining surface. Its features are, The grinding method for the workpiece comprises the following steps: The holding step involves holding the workpiece on the first holding surface and the second holding surface, respectively; and In the grinding step, after the holding step, the chuck table is moved relative to the grinding unit along the first direction, and while the plurality of grinding tools are moved relative to the reference surface in stages along the second direction in such a way that the workpiece held by the first holding surface and the second holding surface respectively reaches a predetermined finished thickness, the rotating plurality of grinding tools are brought into contact with the workpiece held by the first holding surface and the second holding surface respectively, thereby grinding the workpiece.

5. The grinding method for a workpiece according to claim 4, wherein, The first retaining surface and the second retaining surface each have a rectangular shape, the rectangular shape having a pair of short sides extending along the first direction and a pair of long sides having a length greater than the length of the short sides and extending along a third direction perpendicular to the first direction and the second direction.

6. The grinding method for a workpiece according to claim 4, wherein, The first retaining portion is spaced apart from the second retaining portion along the first direction.

7. A method for grinding a workpiece, comprising grinding the workpiece using a grinding apparatus. This grinding device has the following features: A chuck table includes: a first holding portion and a second holding portion, the first holding portion having a first holding surface and the second holding portion having a second holding surface, the first holding surface and the second holding surface being parallel to each other and having the same shape; and a reference surface parallel to the first holding surface and the second holding surface, and surrounding the first holding surface and the second holding surface in a top view, the chuck table being configured to hold workpieces using the first holding surface and the second holding surface respectively; A grinding unit having a spindle at the front end of which are mounted grinding wheels for a chuck table and grinding wheels for a workpiece. The grinding wheels for the chuck table are arranged in a ring with a plurality of grinding tools for the chuck table, and the grinding wheels for the workpiece are arranged in a ring with a plurality of grinding tools for the workpiece. A first moving mechanism that moves the chuck table relative to the grinding unit along a first direction parallel to the reference surface, the first holding surface, and the second holding surface; and The second moving mechanism moves the grinding unit relative to the chuck table along a second direction perpendicular to the reference plane, the first holding surface, and the second holding surface. Its features are, The grinding method for the workpiece comprises the following steps: In the surface grinding step, the chuck table is moved relative to the grinding unit on which the grinding wheel for the chuck table is mounted at the front end of the spindle along the first direction, and the plurality of grinding tools for the chuck table are moved relative to each other in stages along the second direction to form a first holding surface fixed at a first height and a second holding surface fixed at a second height, such that the second height is higher than the first height, and the heights of the first holding surface and the second holding surface from the reference plane increase in sequence along the first direction. Meanwhile, the rotating plurality of grinding tools for the chuck table come into contact with the first holding portion and the second holding portion, thereby grinding the first holding portion and the second holding portion of the chuck table. When the second height is greater than the first height, the bottom surface of the first holding portion and the bottom surface of the second holding portion are located in the same plane, wherein the same plane is parallel to the reference plane. The holding step involves holding the workpiece on the first holding surface and the second holding surface respectively after the holding surface grinding step; and In the grinding step, after the holding step, the chuck table is moved relative to the grinding unit, on which the workpiece grinding wheel is mounted at the front end of the spindle, along the first direction. While the plurality of workpiece grinding tools are moved relative to the reference surface in stages along the second direction, such that the workpiece held by the first and second holding surfaces reaches a predetermined finished thickness, the rotating plurality of workpiece grinding tools contact the workpiece held by the first and second holding surfaces, thereby grinding the workpiece. In both top-view and side-view perspectives (perpendicular to the first direction and parallel to the reference plane), there is a gap between the first retaining surface and the second retaining surface.

8. The grinding method for a workpiece according to claim 7, wherein, The first retaining surface and the second retaining surface each have a rectangular shape, the rectangular shape having a pair of short sides extending along the first direction and a pair of long sides having a length greater than the length of the short sides and extending along a third direction perpendicular to the first direction and the second direction.

9. The grinding method for a workpiece according to claim 7, wherein, The first retaining portion is spaced apart from the second retaining portion along the first direction.

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