JP7592365B2 - Method for grinding a workpiece - Google Patents

Description

The present invention relates to a method for grinding a workpiece.

Chips for devices 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 on which many devices are formed into areas containing individual devices.

In recent years, in order to reduce the size and weight of chips, the workpiece is often thinned before being divided. One method for thinning the workpiece is to grind it using a grinding device that has a chuck table that holds the front (lower) side of the workpiece by suction with a holding surface, and a grinding wheel that is provided above the chuck table and has multiple grinding stones that are arranged in a circular pattern.

In such grinding machines, wafers and other workpieces are often thinned using a grinding method also known as in-feed grinding. In this grinding method, the chuck table and the grinding wheel are first rotated with the chuck table positioned above the grinding wheel.

Then, while the chuck table and grinding wheel are kept rotating, the chuck table and grinding wheel are moved relative to each other in the vertical direction so that the end faces (lower faces) of the multiple grinding wheels come into contact with the back surface (upper surface) of the workpiece. This causes the end faces (lower faces) of the multiple grinding wheels to grind the entire back surface (upper surface) of the workpiece. Furthermore, by continuing to move the chuck table and grinding wheel relative to each other in the vertical direction, a portion of the back surface (upper surface) of the workpiece that has a predetermined thickness is removed, thinning the workpiece.

In addition, in such grinding devices, the workpiece may be thinned by a grinding method also known as creep feed grinding (see, for example, Patent Document 1). In this grinding method, the chuck table and the grinding wheel are first separated horizontally, and the end faces (lower faces) of the multiple grinding stones are positioned lower than the back surface (upper surface) of the workpiece and higher than its front surface (lower surface), and the grinding wheel is then rotated.

Then, while the grinding wheel is still rotating, the chuck table and the grinding wheel are moved relatively in the horizontal direction so that the end faces (lower faces) of the outer surfaces of the multiple grinding wheels come into contact with the side of the workpiece. As a result, an end portion having a predetermined thickness on the back surface (upper surface) of the workpiece is ground by the end faces (lower faces) of the outer surfaces of each of the multiple grinding wheels. Furthermore, by continuing to move the chuck table and the grinding wheel relatively in the horizontal direction, the entire area of the back surface (upper surface) of the workpiece is removed, and the workpiece is thinned.

JP 2005-28550 A

The grinding wheel has a bond material, such as a vitrified bond or resin bond with pores, and abrasive grains, such as diamond or cubic boron nitride (cBN), dispersed in the bond material. In creep feed grinding, the workpiece is ground by the abrasive grains exposed on the end face (lower face) side and end face (lower face) of the outer surface of each of the multiple grinding wheels.

However, if grinding debris generated by creep feed grinding adheres to the end face (lower face) and end face (lower face) of the outer surface of the grinding wheel, the abrasive grains may not be fully exposed (clogged) on the end face (lower face) and end face (lower face) of the outer surface of the grinding wheel. In addition, repeated creep feed grinding may cause the abrasive grains exposed on the end face (lower face) and end face (lower face) of the outer surface of the grinding wheel to wear down (become dull).

In these cases, there is a risk of a decrease in the grinding efficiency of the grinding device. For this reason, the grinding device often performs a process (dressing) at an appropriate time to grind the end faces (lower faces) of multiple grinding wheels to prepare them for grinding. Such dressing of the grinding wheels is performed by operating the grinding device in the same way as when grinding the workpiece, with a disk-shaped dressing board held by suction on the chuck table.

Specifically, in a grinding device that performs creep feed grinding, the grinding wheel is first rotated while the chuck table and grinding wheel are separated horizontally and the end faces (lower faces) of the multiple grinding wheels are positioned lower than the upper face of the dressing board and higher than its lower face. Then, while the grinding wheel is still rotating, the chuck table and grinding wheel are moved relatively in the horizontal direction so that the end faces (lower faces) of the outer faces of each of the multiple grinding wheels come into contact with the side of the workpiece.

As a result, the upper surfaces of the sides of the dressing board cut the end portions of the end faces (lower faces) of each of the multiple grinding wheels to a predetermined thickness. Furthermore, by continuing to move the chuck table and the grinding wheel relatively in the horizontal direction, the entire end faces (lower faces) of each of the multiple grinding wheels are cut, and the multiple grinding wheels are dressed (creep feed dressing).

However, it was found that when creep feed grinding is performed on a workpiece after such creep feed dressing, grinding marks are formed on the workpiece with an undulating top surface (with periodic and minute variations in thickness).

In view of this, the object of the present invention is to provide a method for grinding a workpiece that can reduce the likelihood of such grinding marks being formed on the workpiece, even when creep feed grinding is performed on the workpiece after dressing the grinding wheel.

According to the present invention, a method for grinding a workpiece held on a chuck table using a grinding device including: a chuck table having a holding surface for holding the workpiece and rotating on a rotation axis passing through the center of the holding surface and perpendicular to the holding surface; a grinding unit having a spindle at the tip of which a grinding wheel having a ring-shaped arrangement of multiple grinding wheels is attached, and which rotates the grinding wheel via the spindle to grind the workpiece with the multiple grinding wheels; a first moving mechanism for relatively moving the chuck table and the grinding unit along a first direction parallel to the holding surface; and a second moving mechanism for relatively moving the chuck table and the grinding unit along a second direction perpendicular to the holding surface, the method comprising: a first holding step for holding a dressing board on the holding surface; and a second moving mechanism for relatively moving the chuck table and the grinding unit along a second direction perpendicular to the holding surface, the method comprising: a first holding step for holding a dressing board on the holding surface; and a second moving mechanism for moving the chuck table and the grinding unit along a first direction parallel to the holding surface so that the rotational orbit of the multiple grinding wheels when the grinding wheel is rotated after the first holding step is positioned in the second direction as viewed from the holding surface. The method for grinding a workpiece includes an in-feed dressing step in which the grinding unit is positioned, and then the chuck table and the grinding unit are moved relatively along the second direction while rotating the chuck table and the grinding wheel, thereby dressing the multiple grinding wheels with the dressing board; a second holding step in which, after the in-feed dressing step, the dressing board is removed from the holding surface, and the workpiece is held on the holding surface; and a creep feed grinding step in which, after the second holding step, with the grinding wheel spaced apart from the holding surface in the first direction, the end faces of the multiple grinding wheels are positioned between the front and back surfaces of the workpiece in the second direction, and then, while rotating the grinding wheel, the chuck table and the grinding unit are moved relatively along the first direction, thereby grinding the side of the workpiece farther from the holding surface with the multiple grinding wheels.

In the present invention, the grinding device is operated in the same manner as in-feed grinding, and after dressing (in-feed dressing) of multiple grinding wheels is performed on the dressing board, creep feed grinding is performed on the workpiece.

In this in-feed dressing, multiple grinding wheels come into contact with the dressing board while rotating the chuck table that holds the dressing board by suction as well as the grinding wheel. This ensures that the end faces (lower faces) of the multiple grinding wheels are ground to the same extent even if there is in-plane variation in the dressing board.

In addition, in this in-feed dressing, the distance traveled while in contact with the dressing board (dressing length) is substantially constant for each of the multiple grinding wheels. On the other hand, in the above-mentioned creep feed dressing, the dressing length varies slightly for each of the multiple grinding wheels.

For these reasons, in-feed dressing can suppress variation in the state of multiple grinding wheels after dressing compared to creep feed dressing. As a result, in the present invention, even if creep feed grinding is performed on the workpiece after dressing the grinding wheel, it is possible to reduce the likelihood that grinding marks with wavy upper surfaces (thickness with periodic and fine variations) will be formed on the workpiece.

FIG. 1 is a partially sectional side view showing a schematic diagram of an example of a grinding apparatus. FIG. 2 is a flow chart that illustrates an example of a grinding method. FIG. 3(A) is a perspective view showing a schematic view of the grinding device during the first holding step, and FIG. 3(B) is a partially cross-sectional side view showing a schematic view of the grinding device during the first holding step. FIG. 4(A) is a perspective view showing a schematic view of the grinding device during the in-feed dressing step, and FIG. 4(B) is a partially cross-sectional side view showing a schematic view of the grinding device during the in-feed dressing step. FIG. 5(A) is a perspective view showing a schematic view of the grinding device during the second holding step, and FIG. 5(B) is a partially cross-sectional side view showing a schematic view of the grinding device during the second holding step. FIG. 6(A) is a perspective view showing a schematic view of the grinding device during the creep feed grinding step, and FIG. 6(B) is a partially sectional side view showing a schematic view of the grinding device during the creep feed grinding step.

An embodiment of the present invention will be described with reference to the attached drawings. Fig. 1 is a partially cross-sectional side view showing a schematic diagram of an example of a grinding device. Note that the X-axis direction (front-back direction, first direction) and the Y-axis direction (left-right direction) shown in Fig. 1 are directions perpendicular to each other on a horizontal plane, and the Z-axis direction (up-down direction, second direction) is a direction perpendicular to the X-axis and Y-axis directions (vertical direction).

The grinding device 2 shown in FIG. 1 includes a base 4 that supports or houses each of the components that make up the grinding device 2. A rectangular parallelepiped opening 4a is provided on the upper surface side of the base 4. A chuck table 6 is provided inside the opening 4a. The upper surface of the chuck table 6 is a surface that is roughly parallel to the X-axis direction and the Y-axis direction, and forms a circular holding surface 6a that holds the workpiece or the dressing board.

An X-axis direction moving mechanism (first moving mechanism) 8 is provided inside the opening 4a. The X-axis direction moving mechanism 8 is connected to the chuck table 6 and moves the chuck table 6 along the X-axis direction. This X-axis direction moving mechanism 8 has a screw shaft 10 that extends along the X-axis direction.

A motor 12 for rotating the screw shaft 10 is connected to one end of the screw shaft 10. In addition, a nut portion (not shown) that accommodates balls that roll on the surface of the rotating screw shaft 10 is provided on the surface of the screw shaft 10 where the spiral groove is formed, forming a ball screw.

In other words, when the screw shaft 10 rotates, the balls circulate inside the nut portion, causing the nut portion to move along the X-axis direction. This nut portion is also connected to the chuck table 6. Therefore, when the screw shaft 10 is rotated by the motor 12, the chuck table 6 moves along the X-axis direction together with the nut portion.

Furthermore, a rotational drive source (not shown) such as a motor for rotating the chuck table 6 is connected to the chuck table 6. This rotational drive source rotates the chuck table 6 around a straight line that passes through the center of the holding surface 6a and is perpendicular to the holding surface 6a. In other words, the rotation axis of the chuck table 6 is set to pass through the center of the holding surface 6a and to follow a direction perpendicular to the holding surface 6a.

In addition, inside the chuck table 6, a suction passage (not shown) is formed, one end of which is connected to a suction source (not shown) such as an ejector provided outside the chuck table 6. When this suction source is operated with a workpiece or a dressing board placed on the holding surface 6a, the workpiece or the dressing board is sucked and held on the chuck table 6.

A rectangular parallelepiped support structure 14 is provided behind the chuck table 6 and the X-axis direction movement mechanism 8 (to the right of the paper in FIG. 1). A Z-axis direction movement mechanism (second movement mechanism) 16 is provided on the surface (front) side of the support structure 14. The Z-axis direction movement mechanism 16 is connected to a grinding unit 28 (described below) and moves the grinding unit 28 along the Z-axis direction.

The Z-axis direction movement mechanism 16 is fixed to the surface side of the support structure 14 and has a pair of guide rails 18 that extend along the Z-axis direction. A moving plate 20 is connected to the front side of the pair of guide rails 18 in a manner that allows it to slide along the pair of guide rails 18.

Between the pair of guide rails 18, a screw shaft 22 extending along the Z-axis direction is disposed. A motor 24 for rotating the screw shaft 22 is connected to one end of the screw shaft 22. In addition, a nut portion 26 that accommodates balls that roll on the surface of the rotating screw shaft 22 is provided on the surface of the screw shaft 22 on which a spiral groove is formed, forming a ball screw.

In other words, when the screw shaft 22 rotates, the balls circulate inside the nut portion 26, causing the nut portion 26 to move along the Z-axis direction. The nut portion 26 is also fixed to the back surface (rear surface) of the moving plate 20. Therefore, when the screw shaft 22 is rotated by the motor 24, the moving plate 20 moves along the Z-axis direction together with the nut portion 26.

A grinding unit 28 is attached to the surface (front) side of the moving plate 20. The grinding unit 28 has a hollow cylindrical support member 30 fixed to the surface side of the moving plate 20. A cylindrical housing 32 is housed in the support member 30. The housing 32 is fixed to the bottom wall of the support member 30 via a connecting member 34 provided on its underside.

A cylindrical spindle 36 extending along the Z-axis direction is housed in the housing 32 in a rotatable manner. The tip (lower end) of the spindle 36 is exposed from the housing 32 and protrudes downward from the bottom surface of the support member 30 through an opening provided in the bottom wall of the support member 30. A disk-shaped mount 38 made of metal or the like is fixed to the tip of the spindle 36.

An annular grinding wheel 40 is attached to the underside of the mount 38. The grinding wheel 40 is fixed to the mount 38 by a fastener such as a bolt. The grinding wheel 40 is made of a metal such as aluminum or stainless steel, and has an annular base 42 formed with approximately the same diameter as the mount 38.

The upper surface of the base 42 is fixed to the lower surface of the mount 38. In addition, a plurality of grinding wheels 44 are fixed to the lower surface of the base 42. For example, the plurality of grinding wheels 44 are formed in a rectangular parallelepiped shape and are arranged in a ring shape at approximately equal intervals along the circumferential direction of the base 42.

The grinding wheel 44 is formed by fixing abrasive grains made of diamond or cBN (cubic boron nitride) with a bonding material (bond material) made of metal bond, resin bond, vitrified bond, etc. However, there are no restrictions on the material, shape, structure, size, etc. of the grinding wheel 44. In addition, the number of multiple grinding wheels 44 can be set arbitrarily.

A rotational drive source (not shown), such as a motor, is connected to the base end (upper end) of the spindle 36 to rotate the spindle 36. When this rotational drive source rotates the spindle 36 on a rotation axis along the Z-axis direction, the mount 38 and grinding wheel 40 rotate together with the spindle 36.

When the grinding wheels 44 come into contact with the workpiece held on the chuck table 6 while the grinding wheel 40 is rotating, the upper surface of the workpiece is ground. When the grinding wheels 44 come into contact with the dressing board held on the chuck table 6 while the grinding wheel 40 is rotating, the grinding wheels 44 are dressed.

However, it was found that when creep feed grinding is performed on the workpiece after the creep feed dressing, grinding marks are formed on the workpiece with an undulating top surface (periodic and minute variations in thickness). For example, when the rotation speed of the grinding wheel 40 in creep feed grinding is set to 2500 rpm and the processing feed rate (the relative movement speed in the X-axis direction between the chuck table 6 and the grinding wheel 40) is set to 10 mm/s, it was found that grinding marks are formed on the workpiece with an undulating top surface with a period of approximately 0.24 mm.

Here, under the above creep feed grinding conditions, the chuck table 6 and the grinding wheel 40 move relative to each other along the X-axis direction by 0.24 (= 10/(2500/60)) mm while the grinding wheel 40 rotates once. In other words, each of the multiple grinding wheels 44 comes into contact with the workpiece at a period of 0.24 mm in the X-axis direction and grinds its upper surface.

The inventors therefore discovered that the variation in the condition of the multiple grinding wheels 44 was the cause of the formation of the grinding marks described above. The inventors then discovered that this variation in condition was caused by creep feed dressing, and invented the grinding method shown in Figure 2.

Figure 2 is a flow chart that shows a schematic example of a grinding method for grinding a workpiece held on the chuck table 6 using the grinding device 2. In this method, first, a dressing board is held on the holding surface 6a of the chuck table 6 (first holding step: S1).

Figure 3 (A) is a perspective view showing the grinding device 2 during the first holding step (S1), and Figure 3 (B) is a partially cross-sectional side view showing the grinding device 2 during the first holding step (S1). The dressing board 1 shown in Figures 3 (A) and 3 (B) has a disk-like shape with a diameter shorter than the holding surface 6a.

The dressing board 1 is formed by kneading abrasive grains made of, for example, silicon carbide (SiC) or aluminum oxide (Al ₂ O ₃ ) with a binder made of a vitrified bond or a resin bond, and then firing the mixture. Furthermore, the dressing board 1 is integrated with the support plate 3.

The support plate 3 has a disk-like shape with a diameter longer than that of the dressing board 1 and shorter than that of the holding surface 6a. The support plate 3 is made of a resin such as polyvinyl chloride, and the dressing board 1 is attached to the center of its upper surface with an adhesive. There are no restrictions on the material, shape, structure, or size of the dressing board 1 and the support plate 3.

In the first holding step (S1), first, the X-axis direction moving mechanism 8 moves the chuck table 6 along the X-axis direction so as to move the chuck table 6 further away from the grinding unit 28 than in the state shown in FIG. 1. Next, the dressing board 1 is brought into the holding surface 6a with the support plate 3 facing down (see FIGS. 3(A) and 3(B)).

Next, the suction source connected to one end of the suction passage formed inside the chuck table 6 is operated. This causes the dressing board 1 to be suction-held to the chuck table 6 via the support plate 3. In other words, the first holding step (S1) is completed.

In the method shown in FIG. 2, after the first holding step (S1), the grinding device 2 is operated in the same manner as in the in-feed grinding described above to dress the multiple grinding wheels 44 with the dressing board 1 (in-feed dressing step: S2).

Figure 4 (A) is a perspective view that shows the state of the grinding device 2 during the in-feed dressing step (S2), and Figure 4 (B) is a partially cross-sectional side view that shows the state of the grinding device 2 during the in-feed dressing step (S2).

In the in-feed dressing step (S2), first, the X-axis movement mechanism 8 moves the chuck table 6 along the X-axis direction so that the rotational trajectory of the multiple grinding stones 44 when the grinding wheel 40 is rotated is positioned in the Z-axis direction as viewed from the center of the holding surface 6a. Next, the rotary drive source connected to the chuck table 6 rotates the chuck table 6, and the rotary drive source connected to the base end of the spindle 36 rotates the grinding wheel 40 via the spindle 36.

Next, while rotating the chuck table 6 and the grinding wheel 40, the Z-axis movement mechanism 16 moves the grinding unit 28 along the Z-axis direction so that the end faces (lower faces) of the grinding wheels 44 come into contact with the upper surface of the dressing board 1 (see Figures 4(A) and 4(B)). As a result, the end faces (lower faces) of each of the grinding wheels 44 are ground by the upper surface of the dressing board 1. Furthermore, as the Z-axis movement mechanism 16 continues to move the grinding unit 28 along the Z-axis direction, a portion having a predetermined thickness on the end face (lower face) side of the grinding wheels 44 is ground, and the grinding wheels 44 are dressed.

When dressing of the grinding wheels 44 is completed in this manner, the rotation of the chuck table 6 and the grinding wheel 40 is stopped, and the Z-axis movement mechanism 16 moves the grinding unit 28 along the Z-axis direction so as to separate the end faces (lower surfaces) of the grinding wheels 44 from the upper surface of the dressing board 1. This completes the in-feed dressing step (S2).

In the method shown in FIG. 2, after the in-feed dressing step (S2), the workpiece is held on the holding surface 6a of the chuck table 6 (second holding step: S3). FIG. 5(A) is a perspective view showing the state of the grinding device 2 during the second holding step (S3), and FIG. 5(B) is a partially sectional side view showing the state of the grinding device 2 during the second holding step (S3).

The workpiece 11 shown in Figures 5(A) and 5(B) has a disk-like shape with a diameter shorter than the holding surface 6a. This workpiece 11 is, for example, a disk-like wafer made of a semiconductor material such as Si (silicon), SiC (silicon carbide) or GaN (gallium nitride), and has a large number of devices such as ICs or LSIs formed on its surface.

A disk-shaped protective tape having the same diameter as the workpiece 11 may be attached to the surface of the workpiece 11. When protective tape is attached to the surface of the workpiece 11 in this manner, the impact applied to the device when the workpiece 11 is ground is mitigated, reducing the likelihood of the device being damaged. In addition, the workpiece 11 does not need to have a device formed thereon.

In the second holding step (S3), first, the X-axis direction moving mechanism 8 moves the chuck table 6 along the X-axis direction so as to separate the chuck table 6 from the grinding unit 28. Next, the operation of the suction source connected to one end of the suction path formed inside the chuck table 6 is stopped. Next, the dressing board 1 integrated with the support plate 3 is transported out from the holding surface 6a.

Next, the workpiece 11 is brought in with its surface facing down onto the holding surface 6a (see Figures 5(A) and 5(B)). Next, the suction source connected to one end of the suction passage formed inside the chuck table 6 is operated. This causes the workpiece 11 to be suction-held on the chuck table 6. In other words, the second holding step (S3) is completed.

In the method shown in FIG. 2, after the second holding step (S3), the side of the workpiece 11 farther from the holding surface 6a (the back (upper) side) is ground (creep feed grinding) with a plurality of grinding wheels 44 (creep feed grinding step: S4). FIG. 6(A) is a perspective view showing the state of the grinding device 2 during the creep feed grinding step (S4), and FIG. 6(B) is a partially sectional side view showing the state of the grinding device 2 during the creep feed grinding step (S4).

In the creep feed grinding step (S4), first, the Z-axis movement mechanism 16 moves the grinding unit 28 along the Z-axis direction so that the end faces (lower faces) of the multiple grinding wheels 44 are lower than the back surface (upper surface) of the workpiece 11 and higher than its front surface (lower face). Next, the rotary drive source connected to the base end of the spindle 36 rotates the grinding wheel 40 via the spindle 36.

Next, while rotating the grinding wheel 40, the X-axis direction moving mechanism 8 moves the chuck table 6 along the X-axis direction so that the end faces (lower faces) of the outer surfaces of the grinding wheels 44 come into contact with the side of the workpiece 11 (see Figures 6(A) and 6(B)). As a result, the end faces (lower faces) of the outer surfaces of each of the grinding wheels 44 and the end faces (lower faces) grind an end portion having a predetermined thickness on the back surface (upper surface) of the workpiece 11. Furthermore, as the X-axis direction moving mechanism 8 continues to move the chuck table 6 along the X-axis direction, the entire area of the back surface (upper surface) of the workpiece 11 is ground, and the workpiece 11 is thinned.

Once the workpiece 11 has been thinned in this manner, the rotation of the grinding wheel 40 is stopped, and the Z-axis movement mechanism 16 moves the grinding unit 28 along the Z-axis direction so as to separate the end faces (lower surfaces) of the multiple grinding stones 44 from the upper surface of the dressing board 1. This completes the creep feed grinding step (S4).

In the method shown in FIG. 2, after in-feed dressing of multiple grinding wheels 44 is performed on the dressing board 1, creep feed grinding is performed on the workpiece 11.

In this in-feed dressing, multiple grinding wheels 44 come into contact with the dressing board 1 while rotating not only the grinding wheel 40 but also the chuck table 6, which holds the dressing board 1 by suction. As a result, even if there is in-plane variation in the dressing board 1, the end faces (lower faces) of each of the multiple grinding wheels 44 are ground to the same extent.

In addition, in this in-feed dressing, the distance traveled while in contact with the dressing board 1 (dressing length) is substantially constant for each of the multiple grinding wheels 44. On the other hand, when multiple grinding wheels 44 are dressed (creep feed dressing) by operating the grinding device 2 in the same manner as in creep feed grinding, the dressing length varies slightly for each of the multiple grinding wheels 44.

For these reasons, in-feed dressing can suppress variation in the state of the multiple grinding wheels 44 after dressing, compared to creep feed dressing. As a result, in the method shown in FIG. 2, even if creep feed grinding is performed on the workpiece 11 after dressing the grinding wheels 44, the likelihood of grinding marks on the workpiece 11 having an undulating upper surface (periodic and fine variations in thickness) can be reduced.

The above-mentioned method is one aspect of the present invention, and the present invention is not limited to the above-mentioned method. For example, in the present invention, the chuck table 6 may be configured to be movable in the Y-axis direction and/or the Z-axis direction, and the grinding unit 28 may be configured to be movable in the X-axis direction and/or the Y-axis direction.

In addition, the structures and methods of the above-described embodiments can be modified as appropriate without departing from the scope of the present invention.

2: Grinding device 4: Base (4a: opening)
6: Chuck table (6a holding surface)
8: X-axis direction movement mechanism (first movement mechanism)
10: Screw shaft 12: Motor 14: Support structure 16: Z-axis direction movement mechanism (second movement mechanism)
18: Guide rail 20: Moving plate 22: Screw shaft 24: Motor 26: Nut portion 28: Grinding unit 30: Support member 32: Housing 34: Connection member 36: Spindle 38: Mount 40: Grinding wheel 42: Base 44: Grinding stone 1: Dressing board 3: Support plate 11: Workpiece

Claims (1)

a chuck table having a holding surface for holding a workpiece and rotating about a rotation axis passing through a center of the holding surface and perpendicular to the holding surface;
a grinding unit having a spindle with a grinding wheel having a plurality of grinding stones arranged in a ring attached to its tip, the grinding wheel being rotated via the spindle to grind the workpiece with the plurality of grinding stones;
a first moving mechanism that relatively moves the chuck table and the grinding unit along a first direction parallel to the holding surface;
a second moving mechanism that relatively moves the chuck table and the grinding unit along a second direction perpendicular to the holding surface;
A method for grinding a workpiece held on a chuck table by using a grinding apparatus comprising:
A first holding step of holding a dressing board on the holding surface;
an in-feed dressing step of positioning the chuck table and the grinding unit so that the rotational orbits of the multiple grinding wheels when the grinding wheel is rotated are positioned in the second direction as viewed from the holding surface after the first holding step, and then dressing the multiple grinding wheels with the dressing board by relatively moving the chuck table and the grinding unit along the second direction while rotating the chuck table and the grinding wheel;
After the in-feed dressing step, a second holding step of removing the dressing board from the holding surface and then holding the workpiece on the holding surface;
a creep feed grinding step in which, after the second holding step, end faces of the plurality of grinding wheels are positioned between the front and back surfaces of the workpiece in the second direction with the grinding wheel spaced from the holding surface in the first direction, and then the chuck table and the grinding unit are moved relatively along the first direction while rotating the grinding wheel, thereby grinding the side of the workpiece farther from the holding surface with the plurality of grinding wheels;
A method for grinding a workpiece, comprising:

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