JP2023051365A - Workpiece grinding method - Google Patents

Abstract

To provide a grinding method for workpiece capable of promoting the self-sharpening action of a plurality of grindstones without turning down the holding power of a binder for holding abrasive grains.SOLUTION: A grinding method for workpiece comprises grinding the ground face side of the workpiece after forming a toric groove on the ground face of the workpiece. In this grinding case, the ground face side of the workpiece is ground while an area near the ground face (underside) of respective side faces of a plurality of grindstones collides with the groove side formed on the ground face of the workpiece. Such a collision makes a binder of the ground face side of the workpiece easy to be ground. Accordingly, the self-sharpening action of the grindstones respectively can be promoted without turning down the holding power of the binder for holding abrasive grains.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a method of grinding a disk-shaped workpiece for grinding the surface side of the workpiece so that the entire area of the disk-shaped workpiece has a finished thickness.

Device chips such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured, for example, by dividing a workpiece such as a wafer having a large number of devices formed on its surface into regions each including individual devices.

Furthermore, the workpiece is often thinned before being divided for the purpose of reducing the size and weight of chips. The thinning of the workpiece is performed, for example, by grinding the back side of the workpiece with a grinding device. Such a grinding apparatus has a holding surface (upper surface) shaped to correspond to the side surface of a cone, and includes a chuck table rotatable about a straight line passing through the center of the holding surface as a rotation axis.

Further, above the chuck table, a grinding unit having a spindle to which an annular grinding wheel can be attached is provided. The grinding wheel includes an annular wheel base, and a plurality of grinding wheels each having a rectangular parallelepiped shape and arranged discretely along the circumferential direction of the wheel base. Each of the plurality of grinding wheels also includes a bond and abrasive grains dispersed within and held by the bond.

In this grinding apparatus, a workpiece is generally held on a chuck table via a protective tape for protecting devices formed on the surface of the workpiece (see, for example, Patent Document 1). Then, in a state in which both the chuck table and the spindle with the grinding wheel attached to the tip are rotating, the grinding surface (lower surface) of each of the plurality of grinding wheels is brought into contact with the back surface (upper surface) of the workpiece. Thereby, the back side of the workpiece is ground.

Japanese Patent Application Laid-Open No. 2003-209080

When a hard structure such as a wafer made of silicon carbide (SiC) or sapphire (Al ₂ O ₃ ) is exposed on the back side of the workpiece, a plurality of grinding wheels are used as the workpiece is ground. The abrasive grains exposed on the respective grinding surfaces (lower surfaces) are severely worn (loose). In this case, there is a risk that the driving current of the motor that rotates the grinding wheel including the plurality of grinding wheels via the spindle will increase.

Therefore, in such a case, self-sharpening of each of the plurality of grinding wheels (bonding material on the grinding surface side is scraped off and new abrasive grains are exposed on the grinding surface) accompanying the grinding of the workpiece. need to be promoted. In order to promote self-sharpening, for example, a brittle material may be used as a binder contained in each of a plurality of grinding wheels. However, in this case, the holding force of the bonding material that holds the abrasive grains is weakened, which may make it difficult to grind the workpiece.

In view of this point, an object of the present invention is to provide a method of grinding a workpiece capable of promoting the self-sharpening of each of a plurality of grinding wheels without weakening the holding power of the binder that holds the abrasive grains. is to provide

According to the present invention, an annular groove concentric with a disk-shaped workpiece and having a depth shallower than the difference between the original thickness and the finished thickness of the workpiece is formed on the workpiece. a step of forming grooves on the surface; after the step of forming grooves, the work piece and a plurality of grinding wheels are arranged discretely and have an outer diameter longer than the radius of the work piece; By bringing the grinding surface of each of the plurality of grinding wheels into contact with the ground surface of the workpiece while both the grinding wheel and the grinding wheel are rotating, the entire area of the workpiece is the finished thickness. and a grinding step of grinding the surface side of the workpiece to be ground so that the workpiece is ground.

Preferably, the grinding step utilizes an annular rough grinding wheel on which a plurality of coarse grinding wheels, each containing coarse grinding grains, are discretely arranged to grind the workpiece into the rough grinding wheel. A rough grinding step for grinding the surface to be ground, and after the rough grinding step, an annular grinding wheel for finish grinding on which a plurality of grinding wheels for finish grinding, each containing abrasive grains for finish grinding, are separately arranged. and a finish grinding step of grinding the side of the surface to be ground of the workpiece so that the workpiece has the finish thickness.

Preferably, in the step of forming the groove, the annular cutting blade is rotated, and the cutting blade is moved along the direction perpendicular to the surface to be ground of the workpiece. and after the cutting step, rotating the workpiece at least once along the circumferential direction of the workpiece while the cutting blade is rotated.

Alternatively, the grooving step includes: the work piece and a plurality of grooving grinding wheels arranged discretely; By bringing the grinding surface of each of the plurality of groove-forming grinding wheels into contact with the surface to be ground of the workpiece while both the annular groove-forming grinding wheel having a diameter and the grinding wheel for groove-forming are rotating. be implemented.

In the present invention, an annular groove is formed in the ground surface of the workpiece, and then the ground surface side of the workpiece is ground. In this case, the grinding of the surface to be ground of the workpiece is performed while the regions near the grinding surfaces of the side surfaces of the plurality of grinding wheels collide with the side surfaces of the grooves formed in the surface to be ground of the workpiece. will be

When such a collision occurs, the bonding material on the grinding surface side of the workpiece is likely to be scraped off. As a result, in the present invention, the self-sharpening of each of the plurality of grinding wheels can be promoted without weakening the holding power of the binder that holds the abrasive grains.

FIG. 1 is a flow chart schematically showing an example of a grinding method for a workpiece. FIG. 2 is a flow chart schematically showing an example of the groove forming step. FIG. 3 is a perspective view schematically showing an example of a cutting device. Each of FIGS. 4A and 4B is a partial cross-sectional side view schematically showing how grooves are formed in a ground surface of a workpiece using a cutting device. FIG. 5 is a flow chart that schematically shows an example of the grinding step. FIG. 6 is a perspective view schematically showing an example of a grinding device. FIG. 7 is a plan view schematically showing the structure of the turntable and its surroundings. Each of FIGS. 8A and 8B is a partial cross-sectional side view schematically showing how the grinding machine is used to grind the surface side of the workpiece. Each of FIGS. 9A and 9B is a partial cross-sectional side view schematically showing how grooves are formed on a ground surface of a workpiece using a grinding device.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a flow chart schematically showing an example of a grinding method for a workpiece having many devices formed on its surface. In this method, first, an annular groove concentric with a disk-shaped workpiece and having a depth shallower than the difference between the original thickness and the finished thickness of the workpiece is formed on the ground surface of the workpiece. (groove forming step: S1).

FIG. 2 is a flow chart schematically showing an example of the groove forming step (S1). In this groove forming step (S1), after the cutting blade is cut into the ground surface of the workpiece along the direction perpendicular to the ground surface of the workpiece (cutting step: S11), The workpiece is rotated at least once along the circumferential direction of the workpiece (rotating step: S12).

FIG. 3 is a perspective view schematically showing an example of a cutting device capable of performing the cutting step (S11) and the rotating step (S12). The X1-axis direction (front-rear direction, machining feed direction) and the Y1-axis direction (left-right direction, indexing feed direction) shown in FIG. ) is a direction perpendicular to the X1-axis direction and the Y1-axis direction (vertical direction, cutting feed direction).

The cutting device 2 shown in FIG. 3 includes a base 4 on which each component is mounted. A cassette table 8 on which the cassette 6 is placed is installed at the corner of the base 4 . The cassette 6 accommodates a frame unit 11 in which a workpiece and an annular frame are integrated via, for example, a disk-shaped dicing tape attached to the surface of the workpiece.

This workpiece is, for example, a disk-shaped wafer made of silicon carbide, sapphire, or the like, on which a large number of devices are formed. Also, the cassette table 8 is connected to a cassette table moving mechanism (not shown), and is movable along the Z1 axis direction, for example. This cassette table moving mechanism adjusts the height of the cassette 6 placed on the cassette table 8 so that the frame unit 11 can be properly carried in and out.

A cover 10 is attached to the top of the base 4 to cover the upper surface of the base 4 . Inside the cover 10, a cutting unit 12 having a spindle (cutting blade spindle) to which an annular cutting blade can be attached is housed. This cutting unit 12 is connected to a cutting unit moving mechanism (not shown), and is movable along the Y1-axis direction and the Z1-axis direction, for example.

A chuck table 14 capable of holding the frame unit 11 by suction is provided below the cutting unit 12 . The chuck table 14 is connected to a chuck table moving mechanism (not shown) and is movable along the X1 axis direction, for example. Also, the chuck table 14 is connected to a rotation mechanism (not shown), and is rotatable about a straight line substantially parallel to the Z1-axis direction as a rotation axis.

Furthermore, the side surface 10a of the cover 10 is provided with a touch panel 16 serving as a user interface. A warning light (pilot lamp) 18 is provided on the upper surface 10b of the cover 10. As shown in FIG. The constituent elements of the cutting device 2 described above are connected to a control unit (not shown).

This control unit has a central processing unit (CPU) and storage devices including a main storage device (volatile memory) and an auxiliary storage device (non-volatile memory), and controls the operations of the components of the cutting device 2 described above. Control. For example, the control unit rotates the spindle of the cutting unit 12 and moves the cutting unit 12 and/or the chuck table 14 so that a workpiece held on the chuck table 14 is cut.

4A and 4B are partial cross-sectional side views schematically showing how grooves are formed on the back surface of the workpiece (surface to be ground) using the cutting device 2. FIG. . When forming these grooves, first, a frame is moved from the cassette 6 to the chuck table 14 so that the center of the workpiece 15 and the center of the chuck table 14 overlap with each other via the dicing tape 13 attached to the surface 15a. Transport the unit 11 .

Next, the chuck table 14 is operated so as to suck and hold the workpiece 15 via the dicing tape 13 . Next, the cutting unit 12 and/or the chuck table 14 are moved so that the cutting blade 20 of the cutting unit 12 is positioned directly above the intermediate region between the center and the outer periphery of the workpiece 15 .

Next, while rotating the spindle (spindle for cutting blade) 22 of the cutting unit 12, the lower end reaches a depth shallower than the difference between the original thickness and the finished thickness of the workpiece 15 from the back surface 15b of the workpiece 15. (See FIG. 4A). Next, while rotating the spindle 22, the chuck table 14 is rotated at least once (FIG. 4(B)). As a result, an annular groove 17 concentric with the workpiece 15 and having a depth shallower than the difference between the original thickness and the finished thickness of the workpiece 15 is formed in the back surface 15b of the workpiece 15. .

In the method of grinding a workpiece shown in FIG. 1, after the groove forming step (S1), the back surface (surface to be ground) of the workpiece 15 is ground so that the entire area of the workpiece 15 has a finished thickness. (grinding step: S2). FIG. 5 is a flow chart schematically showing an example of the grinding step (S2). In this grinding step (S2), after the back surface (surface to be ground) 15b side of the workpiece 15 is roughly ground (rough grinding step: S21), the back surface (surface to be ground) 15b side of the workpiece 15 is ground. finish grinding is performed (finish grinding step: S22).

FIG. 6 is a perspective view schematically showing an example of a grinding apparatus capable of performing the rough grinding step (S21) and the finish grinding step (S22). Note that the X2-axis direction (front-rear direction) and the Y2-axis direction (left-right direction) shown in FIG. 6 are directions perpendicular to each other on the horizontal plane, and the Z2-axis direction (vertical direction) It is the direction perpendicular to the axial direction (vertical direction).

A grinding device 24 shown in FIG. 6 includes a base 26 on which each component is mounted. An opening 26a is formed on the front end side of the upper surface of the base 26, and a transport mechanism 28 is provided in the opening 26a. This transport mechanism 28 is, for example, a robot arm having a plurality of joints. Cassette mounting tables 32a and 32b on which the cassettes 30a and 30b are mounted are provided in front of the opening 26a.

In the cassettes 30a and 30b, for example, after the dicing tape 13 is separated from the surface 15a of the workpiece 15 having the grooves 17 formed on the back surface 15b, a new film-like protective tape is attached to the surface 15a. The workpiece 15 is accommodated. The protective tape prevents the devices formed on the front surface 15a of the workpiece 15 from being damaged when the back surface 15b side of the workpiece 15 is ground.

Further, the transport mechanism 28 can not only hold and transport the workpiece 15, but also can turn the workpiece 15 upside down. A position adjusting mechanism 34 for adjusting the position of the workpiece 15 is provided obliquely behind the opening 26a. The position adjustment mechanism 34 includes, for example, a disk-shaped table and a plurality of pins arranged around the table.

The transport mechanism 28, for example, unloads the workpiece 15 from the cassette 30a and loads the workpiece 15 onto the table of the position adjustment mechanism 34 so that the back surface 15b faces upward. By moving a plurality of pins along the radial direction of the table, for example, the center of the workpiece 15 loaded onto the table of the position adjustment mechanism 34 is positioned on a plane parallel to the X2-axis direction and the Y2-axis direction. (X2Y2 coordinate plane) to a predetermined position (coordinates).

A transport mechanism 36 that transports the workpiece 15 is provided behind the transport mechanism 28 and the position adjustment mechanism 34 . A disk-shaped turntable 38 is provided behind the transport mechanism 36 . The turntable 38 is connected to a rotary drive source (not shown) such as a motor, and rotates about a straight line substantially parallel to the Z2-axis direction as a rotation axis.

Three chuck tables 40 capable of holding the workpiece 15 are provided on the upper surface of the turntable 38 . The three chuck tables 40 are provided at approximately equal intervals along the circumferential direction of the turntable 38 . The number of chuck tables 40 provided on the turntable 38 is not limited.

FIG. 7 is a plan view schematically showing the structure of the turntable 38 and its surroundings. In addition, in FIG. 7, some elements are represented by dashed lines for convenience of explanation. The transport mechanism 36 unloads the workpiece 15 aligned by the position adjustment mechanism 34 from the position adjustment mechanism 34 and transports it into the chuck table 40 arranged in the loading/unloading area A adjacent to the transport mechanism 36 .

The turntable 38 rotates, for example, in the directions indicated by the arrows in FIGS. 6 and 7, and moves the three chuck tables 40 in the loading/unloading area A, the rough grinding area B, and the finish grinding area C in this order. Each of the three chuck tables 40 is connected to a rotational drive source (not shown) such as a motor, and rotates about a straight line substantially parallel to the Z2-axis direction as a rotation axis.

The chuck table 40 has a disk-shaped frame made of, for example, ceramics. A concave portion having a circular opening at the upper end is formed on the upper surface side of the frame, and a disk-shaped porous plate made of ceramics or the like is fixed to the concave portion.

The upper surface of the chuck table 40 has a shape corresponding to the side surface of a cone with the center slightly protruding from the outer edge, and functions as a holding surface 40a that holds the surface 15a side of the workpiece 15. As shown in FIG. That is, each chuck table 40 has a holding surface 40a for holding the workpiece 15 on its top.

Specifically, the holding surface 40 a communicates with a suction source (not shown) such as a vacuum pump through a suction path (not shown) formed inside the chuck table 40 . When this suction source is operated, a suction force acts on the space near the holding surface 40a. Therefore, when the suction source is operated with the surface 15 a side of the workpiece 15 placed on the holding surface 40 a, the workpiece 15 is sucked and held by the chuck table 40 .

A columnar support structure 42 is provided behind each of the rough grinding area B and the finish grinding area C (see FIG. 6). A Z2-axis movement mechanism 44 is provided on the front side of each support structure 42 . This Z2-axis movement mechanism 44 includes a pair of guide rails 46 that are substantially parallel to the Z2-axis direction.

A moving plate 48 is attached to the front side of the pair of guide rails 46 in a slidable manner. A nut portion (not shown) constituting a ball screw is fixed to the rear surface (back surface) side of the moving plate 48, and a screw shaft 50 substantially parallel to the guide rail 46 rotates on the nut portion. connected as possible.

A motor 52 is connected to the upper end of the screw shaft 50 . By rotating the screw shaft 50 with the motor 52, the moving plate 48 moves along the guide rail 46 in the Z2-axis direction. A fixture 54 is provided on the front (surface) side of the moving plate 48 . The fixture 54 supports a grinding unit 56 comprising a spindle housing 58 secured to the fixture 54 .

A spindle (grinding wheel spindle) 60 is accommodated in the spindle housing 58 so as to be rotatable about a straight line substantially parallel to the Z2 axis direction as a rotation axis. The lower end of the spindle 60 is exposed from the lower end surface of the spindle housing 58, and a disk-shaped mount 62 is fixed to the lower end of the spindle 60. As shown in FIG.

A rough grinding wheel 64 is attached to the lower surface of the mount 62 of the grinding unit 56 on the rough grinding area B side. The rough grinding wheel 64 is made of a metal material such as stainless steel or aluminum and has an annular rough grinding wheel base with an outer diameter approximately equal to the diameter of the mount 62 . Both the inner and outer diameters of the grinding wheel 64 for rough grinding are longer than the radius of the workpiece 15 described above.

A plurality of grinding wheels for rough grinding are discretely arranged on the lower surface of the wheel base for rough grinding. ing. The spindle housing 58 of the grinding unit 56 on the rough grinding area B side accommodates a rotary drive source (not shown) for rough grinding such as a motor connected to the upper end side of the spindle 60 .

When the rotary drive source for rough grinding operates, the grinding wheel 64 for rough grinding rotates together with the spindle 60 . At this time, the plurality of rough-grinding grinding wheels included in the rough-grinding wheel 64 trace an annular trajectory whose outer diameter and inner diameter are both longer than the radius of the workpiece 15 . Also, this trajectory overlaps the center of the holding surface 40a of the chuck table 40 positioned in the rough grinding area B. As shown in FIG.

Further, near the grinding wheel 64 for rough grinding, a liquid such as pure water (grinding liquid) is applied to the contact point (processing point) between the back surface 15b of the workpiece 15 and the lower surface (grinding surface) of the plurality of grinding wheels for rough grinding. A liquid supply nozzle (not shown) capable of supplying a liquid) is provided. However, instead of or together with the liquid supply nozzle, the rough grinding wheel 64 may be provided with a liquid supply port used for supplying the liquid.

Similarly, a grinding wheel 66 for finish grinding is attached to the lower surface of the mount 62 of the grinding unit 56 on the finish grinding area C side. The finish grinding wheel 66 is made of metal such as stainless steel or aluminum and has an annular finish grinding wheel base with an outer diameter approximately equal to the diameter of the mount 62 . Both the inner diameter and the outer diameter of the finish grinding wheel 66 are longer than the radius of the workpiece 15 described above.

Abrasive grains for finish grinding such as diamond suitable for finish grinding (for example, abrasive grains with a finer average grain size than abrasive grains for rough grinding) are attached to the lower surface of the wheel base for finish grinding with a bond such as vitrified or resinoid. A plurality of fixed grinding wheels for finish grinding are arranged discretely. The spindle housing 58 of the grinding unit 56 on the finish grinding area C side accommodates a finish grinding rotary drive source (not shown) such as a motor connected to the upper end side of the spindle 60 .

When the rotary drive source for finish grinding operates, the grinding wheel 66 for finish grinding rotates together with the spindle 60 . At this time, the plurality of finish-grinding grinding wheels included in the finish-grinding grinding wheel 66 trace an annular trajectory whose outer diameter and inner diameter are both longer than the radius of the workpiece 15 . Also, this trajectory overlaps the center of the holding surface 40a of the chuck table 40 positioned in the finish grinding area C. As shown in FIG.

Further, beside the grinding wheel 66 for finish grinding, liquid such as pure water (grinding liquid) is applied to the contact point (processing point) between the back surface 15b of the workpiece 15 and the lower surface (grinding surface) of a plurality of grinding wheels for finish grinding. A liquid supply nozzle (not shown) capable of supplying a liquid) is provided. However, instead of or together with the liquid supply nozzle, the finish grinding wheel 66 may be provided with a liquid supply port used for supplying the liquid.

The workpiece 15 held on the chuck table 40 is sequentially ground by the two sets of grinding units 56 described above. Specifically, the workpiece 15 is ground in the rough grinding region B by the grinding unit 56 on the rough grinding region B side, and then ground in the finish grinding region C by the grinding unit 56 on the finish grinding region C side.

Further, in front of the loading/unloading area A and on the side of the transport mechanism 36, a transport mechanism 68 for transporting the ground workpiece 15 is provided. A cleaning unit 70 for cleaning the workpiece 15 carried out from the chuck table 40 by the transport mechanism 68 is provided in front of the transport mechanism 68 .

The cleaning unit 70 includes, for example, a spinner table that rotates while holding the front surface 15a of the workpiece 15, and a back surface (surface to be ground) 15b of the workpiece 15 held by the spinner table for cleaning. and a nozzle for ejecting fluid. The workpiece 15 cleaned by the cleaning unit 70 is transported from the cleaning unit 70 by the transport mechanism 28 and loaded into, for example, the cassette 30b.

Further, grinding device 24 may include components other than those described above. For example, the grinding machine 24 may include a touch panel configured by a touch sensor for inputting instructions from the operator to the grinding machine 24 and a display for outputting various information to the operator. The constituent elements of the grinding device 24 described above are connected to a control unit (not shown).

This control unit has a central processing unit (CPU) and a memory device including a main memory device (volatile memory) and an auxiliary memory device (non-volatile memory), and controls the operation of the components of the grinding machine 24 described above. Control. For example, the control unit controls the components described above such that the workpiece 15 held on the chuck table 40 goes from the original thickness to the finished thickness.

8A and 8B are partial cross-sectional side views schematically showing how the grinding device 24 is used to grind the back surface 15b side of the workpiece 15. FIG. During this grinding, first, the conveying mechanism 28 unloads the workpiece 15 from the cassette 30a and carries it onto the upper surface of the disk-shaped table of the position adjusting mechanism 34 so that the back surface 15b of the workpiece 15 faces upward. do. Thereby, the workpiece 15 is supported by the table through the protective tape 19 attached to the surface 15a.

Next, by moving a plurality of pins arranged around the table along the radial direction of the table, the center of the workpiece 15 is positioned at specific coordinates on the X2Y2 coordinate plane. Next, the conveying mechanism 36 carries out the workpiece 15 from the table of the position adjusting mechanism 34 and carries it into the holding surface 40a of the chuck table 40 positioned in the carrying-in/carrying-out area A. As shown in FIG. Thereby, the workpiece 15 is supported by the chuck table 40 via the protective tape 19 .

Next, the chuck table 40 is operated so as to suck and hold the surface 15 a side of the workpiece 15 through the protective tape 19 . Next, the turntable 38 is rotated so that the chuck table 40 holding the workpiece 15 is positioned in the rough grinding area B. As shown in FIG. Next, both the chuck table 40 positioned in the rough grinding area B and the spindle 60 of the grinding unit 56 on the rough grinding area B side are rotated.

Further, as the spindle 60 rotates, the mount 62 and the rough grinding wheel 64 rotate along the circumferential direction of the rough grinding wheel 64 (rough grinding wheel base 64a). Next, while rotating the chuck table 40 and the grinding wheel 64 for rough grinding, the lower surface (grinding surface) of the plurality of grinding wheels 64b for rough grinding is brought into contact with the back surface 15b of the workpiece 15, so that the rough grinding region B side is moved. lowers the grinding unit 56 (see FIG. 8(A)).

As a result, the back surface 15b side of the workpiece 15 is ground and removed by the undersides of the plurality of rough grinding grindstones 64b. This grinding (rough grinding) is continued until the thickness of the workpiece 15 reaches a predetermined thickness greater than the finished thickness. For example, the rough grinding is continued until the depth of the grooves 17 formed in the back surface 15b of the workpiece 15 is 1/3 to 1/10 times.

Next, rotation of both the chuck table 40 positioned in the rough grinding area B and the spindle 60 of the grinding unit 56 on the rough grinding area B side is stopped, and the grinding unit 56 is raised. Next, the turntable 38 is rotated so that the chuck table 40 holding the workpiece 15 is positioned in the finish grinding area C. As shown in FIG. Next, both the chuck table 40 positioned in the finish grinding area C and the spindle 60 of the grinding unit 56 on the finish grinding area C side are rotated.

Further, along with the rotation of the spindle 60, the mount 62 and the finish grinding wheel 66 rotate along the circumferential direction of the finish grinding wheel 66 (finish grinding wheel base 66a). Next, while rotating the chuck table 40 and the grinding wheel 66 for finish grinding, the final grinding area C side is moved so that the lower surface (grinding surface) of the plurality of grinding wheels 66b for finish grinding is brought into contact with the back surface 15b of the workpiece 15. lowers the grinding unit 56 (see FIG. 8(B)).

As a result, the back surface 15b side of the workpiece 15 is ground and removed by the plurality of finish-grinding grinding wheels 66b. This grinding (finish grinding) is continued until the thickness of the workpiece 15 reaches the finish thickness. That is, the groove 17 formed in the back surface 15b of the workpiece 15 by the finish grinding disappears. As a result, the entire area of the workpiece 15 has a finished thickness.

In the above-described method of grinding a workpiece, the annular groove 17 is formed in the back surface 15b of the workpiece 15, and then the back surface 15b side of the workpiece 15 is ground. In this case, among the side surfaces of the plurality of grinding wheels (the grinding wheel 64b for rough grinding and the grinding wheel 66b for finish grinding), the region near the lower surface is one of the side surfaces of the groove 17 formed in the back surface 15b of the workpiece 15. The back surface 15b side of the workpiece 15 is ground while colliding with the area near the upper surface.

When such a collision occurs, the bonding material on the lower surface side of the workpiece 15 is likely to be scraped off. As a result, in the above-described method for grinding a workpiece, a plurality of grinding wheels (rough grinding It is possible to promote self-sharpening of the grinding wheel 64b for grinding and the grinding wheel 66b) for finish grinding.

The contents described above are one aspect of the present invention, and inventions having features different from the contents described above are also included in the present invention. For example, the groove forming step of the present invention may utilize grinding, plasma etching, or laser ablation to form grooves in the back surface 15b of the workpiece 15. FIG.

9A and 9B are partial cross-sectional side views schematically showing how grooves are formed on the back surface (surface to be ground) 15b of the workpiece 15 using a grinding apparatus. be. A grinding device 72 shown in each of FIGS. 9A and 9B has a chuck table 74 . The chuck table 74 has a disk-shaped frame made of ceramics, for example.

A concave portion having a circular opening at the upper end is formed on the upper surface side of the frame, and a disk-shaped porous plate made of ceramics or the like is fixed to the concave portion. The upper surface of the chuck table 74 is formed in a shape corresponding to the side surface of a cone with the center slightly protruding from the outer edge, and functions as a holding surface 74a that holds the surface 15a side of the workpiece 15. As shown in FIG.

Specifically, the holding surface 74 a communicates with a suction source (not shown) such as a vacuum pump through a suction path (not shown) formed inside the chuck table 74 . When this suction source is operated, a suction force acts on the space near the holding surface 74a. Therefore, when the suction source is operated with the surface 15a side of the workpiece 15 placed on the holding surface 74a, the workpiece 15 is sucked and held by the chuck table 74. FIG.

Furthermore, the chuck table 74 is connected to a chuck table moving mechanism (not shown) and is horizontally movable. A grinding unit 76 is provided above the chuck table 74 . This grinding unit 76 has a spindle 78 that can rotate about a straight line substantially parallel to the vertical direction as a rotation axis.

A disk-shaped mount 80 is fixed to the lower end of the spindle 78 . A groove forming grinding wheel 82 is attached to the lower surface of the mount 80 . The grooving grinding wheel 82 is made of a metal material such as stainless steel or aluminum, and includes an annular grooving wheel base 82 a having an outer diameter approximately equal to the diameter of the mount 80 .

Also, both the inner and outer diameters of the grooving grinding wheel 82 are longer than the radius of the workpiece 15 described above and shorter than the diameter of the workpiece 15 . A plurality of grooving grinding wheels 82b formed by fixing grooving abrasive grains such as diamond with a bond such as vitrified or resinoid are discretely arranged on the lower surface of the grooving wheel base 82a.

In addition, when both the inner diameter and the outer diameter of the grinding wheels (the grinding wheel 64 for rough grinding and the grinding wheel 66 for finish grinding) used in the grinding step of the present invention are shorter than the diameter of the workpiece 15, groove formation Grinding wheel 82 for rough grinding may be the same as this grinding wheel (eg, grinding wheel 64 for rough grinding).

Furthermore, the upper end of the spindle 78 is connected to a rotational drive source (not shown) such as a motor. When the rotary drive source operates, the groove forming grinding wheel 82 rotates together with the spindle 78 . At this time, the plurality of grooving grinding wheels 82b included in the grooving grinding wheel 82 have both outer diameters and inner diameters longer than the radius of the workpiece 15 and larger than the diameter of the workpiece 15. Draw a short circular trajectory.

Further, near the grooving grinding wheel 82, a liquid such as pure water is applied to the contact point (processing point) between the back surface 15b of the workpiece 15 and the lower surface (grinding surface) of the plurality of grooving grinding wheels 82b. A liquid supply nozzle (not shown) capable of supplying a grinding liquid) is provided. However, instead of or together with the liquid supply nozzle, the groove forming grinding wheel 82 may be provided with a liquid supply port used for supplying the liquid.

When forming grooves on the back surface (surface to be ground) 15b of the workpiece 15 using the grinding device 72, first, the center of the workpiece 15 and the surface to be processed 15 are aligned via the protective tape 19 attached to the front surface 15a. The workpiece 15 is conveyed to the chuck table 74 so that the center of the chuck table 74 overlaps.

Next, the chuck table 74 is operated so as to suck and hold the surface 15 a side of the workpiece 15 through the protective tape 19 . Next, the chuck table 74 is moved so that the straight line that is the rotation axis of the spindle 78 (the rotation axis of the grinding wheel 82 for groove formation) passes through the center of the holding surface 74 a of the chuck table 74 . Both the chuck table 74 and the spindle 78 are then rotated.

Next, while rotating the chuck table 74 and the groove-forming grinding wheel 82, the lower surface (grinding surface) of the plurality of groove-forming grinding wheels 82b is brought into contact with the back surface (surface to be ground) 15b of the workpiece 15. Grinding unit 76 is lowered. As a result, the annular region on the back surface 15b side of the workpiece 15 is ground and removed by the lower side of the plurality of groove-forming grinding wheels 82b.

In this grinding, the distance between the lower surfaces of the plurality of groove-forming grinding wheels 82b and the surface 15a of the workpiece 15 is set to a predetermined length that is longer than the finished thickness of the workpiece 15 and thicker than a predetermined thickness. (See FIG. 9A). Next, the rotation of both the chuck table 74 and the spindle 78 is stopped, and the grinding unit 76 is raised (see FIG. 9(B)). As a result, an annular groove 21 concentric with the workpiece 15 and having a depth smaller than the difference between the original thickness and the finished thickness of the workpiece 15 is formed in the back surface 15b of the workpiece 15. .

Also, the groove forming step and the grinding step of the present invention may be performed in a single grinding apparatus that can arbitrarily change the relative positional relationship between the grinding unit and the chuck table. Specifically, in this grinding apparatus, the grinding unit and/or the chuck table are connected to a ball screw type horizontal movement mechanism.

By operating this horizontal movement mechanism, the state where the straight line, which is the rotation axis of the grinding wheel, passes through the center of the holding surface of the chuck table, and the trajectory drawn by the rotating grinding wheel is the center of the holding surface of the chuck table. The grinding unit and the chuck table can be moved relative to each other so as to switch between the state of overlapping with the

In addition, the structure, method, and the like according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention.

2: cutting device 4: base 6: cassette table 8: cassette 10: cover (10a: side surface, 10b: top surface)
Reference Signs List 11: frame unit 12: cutting unit 13: dicing tape 14: chuck table 15: workpiece (15a: front surface, 15b: back surface (surface to be ground))
16: Touch panel 17: Groove 18: Warning light (pilot lamp)
19: Protective tape 20: Cutting blade 21: Groove 22: Spindle (spindle for cutting blade)
24: grinding device 26: base (26a: opening)
28: Transfer mechanism 30a, 30b: Cassette 32a, 32b: Cassette mounting table 34: Position adjustment mechanism 36: Transfer mechanism 38: Turntable 40: Chuck table (40a: holding surface)
42: Support structure 44: Z2-axis movement mechanism 46: Guide rail 48: Movement plate 50: Screw shaft 52: Motor 54: Fixture 56: Grinding unit 58: Spindle housing 60: Spindle (spindle for grinding wheel)
62: Mount 64: Grinding wheel for rough grinding
(64a: wheel base for rough grinding, 64b: grinding wheel for rough grinding)
66: Grinding wheel for finish grinding
(66a: wheel base for finish grinding, 66b: grinding wheel for finish grinding)
68: Conveying mechanism 70: Cleaning unit 72: Grinding device 74: Chuck table (74a: holding surface)
76: grinding unit 78: spindle 80: mount 82: grinding wheel for groove formation
(82a: groove forming wheel base, 82b: groove forming grinding wheel)

Claims (4)

A groove forming step of forming an annular groove in the ground surface of the work piece concentrically with the disk-shaped work piece and having a depth shallower than the difference between the original thickness of the work piece and the finished thickness of the work piece. and,
After the grooving step, both the workpiece and an annular grinding wheel having a plurality of spaced apart grinding wheels and an outer diameter greater than the radius of the workpiece were rotated. In the state, by bringing the grinding surface of each of the plurality of grinding wheels into contact with the surface to be ground of the workpiece, the workpiece is adjusted so that the entire area of the workpiece has the finished thickness. a grinding step of grinding the surface to be ground;
A grinding method for a workpiece, comprising: The grinding step includes
Rough grinding of the surface side of the workpiece using an annular grinding wheel for rough grinding in which a plurality of grinding wheels for rough grinding, each containing abrasive grains for rough grinding, are discretely arranged a grinding step;
After the rough grinding step, an annular finish grinding wheel on which a plurality of finish grinding wheels each containing finish grinding grains are discretely arranged is used to reduce the workpiece to the finish thickness. A finish grinding step of grinding the ground surface side of the workpiece so that it is even.
The method of grinding a workpiece according to claim 1, characterized by comprising: The grooving step includes:
a cutting step of cutting the cutting blade into the surface to be ground of the workpiece along a direction perpendicular to the surface to be ground of the workpiece while the annular cutting blade is rotating;
a rotating step of rotating the workpiece at least once along the circumferential direction of the workpiece while the cutting blade is rotated after the cutting step;
The method of grinding a workpiece according to claim 1 or 2, comprising: In the groove forming step, the workpiece and a plurality of groove-forming grinding wheels are arranged separately, and an outer diameter that is longer than the radius of the workpiece and shorter than the diameter of the workpiece is formed. It is carried out by bringing the grinding surface of each of the plurality of groove-forming grinding wheels into contact with the surface to be ground of the workpiece while both of the annular groove-forming grinding wheel and the groove-forming grinding wheel are rotating. 3. The method of grinding a workpiece according to claim 1 or 2, characterized in that:

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