JP2022091470A - Workpiece grinding method - Google Patents

Abstract

To provide a workpiece grinding method that is able to shorten a processing time when grinding a workpiece by means of a grinding device.SOLUTION: There is provided a workpiece grinding method for grinding a workpiece by using a grinding device, which includes a chuck table having a holding surface for holding the workpiece and having a rotary shaft set along a direction perpendicular to the holding surface and also includes a grinding unit to which a grinding wheel including an annularly-disposed grinding stone is attached and that grinds the workpiece by means of the grinding stone. The method includes a first grinding step of, while rotating the chuck table and the grinding wheel, moving the chuck table and the grinding unit relatively along a direction parallel to the holding surface, and grinding the workpiece from an outer peripheral edge to a center thereof by means of the grinding stone; and a second grinding step of, while keeping the chuck table and the grinding wheel rotated, moving the chuck table and the grinding unit relatively along a direction perpendicular to the holding surface and grinding the workpiece to a predetermined finish thickness by means of the grinding stone.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for grinding a work piece, which grinds the work piece using a grinding device.

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

In recent years, with the miniaturization of electronic devices, the device chips are also required to be thinner. Therefore, a method of grinding and thinning a wafer before dividing the wafer is used. For grinding a wafer, a grinding device including a chuck table having a holding surface for holding a workpiece and a grinding unit for grinding the workpiece is used. The grinding unit is equipped with a grinding wheel including a grinding wheel. Then, the grinding unit grinds the workpiece by rotating the grinding wheel to bring the grinding wheel into contact with the workpiece.

When grinding a workpiece such as a wafer using a grinding device, the chuck table and the grinding unit are arranged so that the center of the workpiece held by the chuck table overlaps with the movement path (rotation path) of the grinding wheel. The positional relationship of is adjusted. Then, when the grinding wheel is lowered toward the holding surface of the chuck table with the chuck table and the grinding wheel rotated, the lower surface of the grinding wheel comes into contact with the upper surface side of the workpiece and the workpiece is moved. Be ground. Such a grinding method is called in-feed grinding.

On the other hand, a grinding method called creep feed grinding may be used for grinding the workpiece. In creep feed grinding, the positional relationship between the chuck table and the grinding unit is such that the grinding wheel is positioned outside the holding surface of the chuck table and the lower surface of the grinding wheel is positioned below the upper surface of the workpiece. Be adjusted. Then, when the chuck table is moved along the direction parallel to the holding surface (horizontal direction) while the grinding wheel is rotated and the chuck table is not rotated, the side surfaces and the lower surface of the grinding wheel are the upper surface of the workpiece. The workpiece is ground in contact with the side (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-28550

When grinding a work piece by creep feed grinding, the chuck table moves horizontally so that one end to the other end of the work piece passes directly under the tip of the movement path (rotational path) of the grinding wheel. The distance (machining feed distance) is set. For example, when the workpiece is a disk-shaped wafer, the machining feed distance is set to at least the diameter of the wafer. In addition, the moving speed (machining feed rate) of the chuck table is maintained below a certain level so that excessive pressure (machining load) is not applied to the workpiece and the grinding wheel when the workpiece comes into contact with the grinding wheel. .. Therefore, there is a limit to shortening the machining feed distance and increasing the machining feed rate, and it is difficult to shorten the machining time and improve the machining efficiency in creep feed grinding.

Further, while the workpiece is being ground by creep feed grinding, the grinding wheel gradually wears due to contact with the workpiece. Therefore, the height position of the lower surface of the grinding wheel may fluctuate during grinding of one workpiece, and the thickness of the workpiece after grinding may vary. In this case, in order to adjust the thickness of the workpiece, a step of further grinding a small amount of the workpiece by creep feed grinding is added. As a result, it is necessary to adjust the positions of the chuck table and the grinding unit and to feed the machining again, which increases the machining time.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method for grinding a workpiece, which can shorten the machining time when grinding the workpiece with a grinding apparatus.

According to one aspect of the present invention, it is a method of grinding a work piece by using a grinding device, and the grinding device has a holding surface for holding the work piece and holds the work piece. It is equipped with a chuck table having a rotation axis set along a direction perpendicular to the surface, and a grinding unit equipped with a grinding wheel including a grinding wheel arranged in an annular shape and grinding the workpiece with the grinding wheel. With the chuck table, the grinding wheel is positioned on the outside of the holding surface, and the lower surface of the grinding wheel is positioned below the upper surface of the workpiece held by the chuck table by a predetermined distance. A preparatory step for adjusting the positional relationship with the grinding unit, and after the preparatory step, the chuck table and the grinding unit are rotated in a direction parallel to the holding surface while rotating the chuck table and the grinding wheel. A first grinding step of grinding the workpiece from the outer peripheral edge to the center with the grinding wheel, and after performing the first grinding step, the chuck table and the grinding wheel are rotated. The chuck table and the grinding unit are relatively moved along the direction perpendicular to the holding surface, and the workpiece is ground to a predetermined finish thickness with the grinding grind. A grinding step and a method of grinding the workpiece including the grinding step are provided.

It is preferable that the method of grinding the workpiece is such that the chuck table and the grinding unit are perpendicular to the holding surface after the first grinding step and before the second grinding step. It further includes a separation step that moves relative to the direction and separates the workpiece from the grinding wheel.

In the method for grinding a workpiece according to one aspect of the present invention, a first grinding step (creep feed grinding) in which the chuck table and the grinding unit are relatively moved along a direction parallel to the holding surface is a chuck table. It is carried out in a rotated state. As a result, the machining feed distance can be shortened and the machining time can be shortened.

Further, in the method for grinding a workpiece according to one aspect of the present invention, a second grinding step (in-feed grinding) in which the chuck table and the grinding unit are relatively moved along a direction perpendicular to the holding surface is the first. It is carried out continuously after one grinding step. This eliminates the need for a step of performing creep feed grinding again in order to adjust the thickness of the workpiece after the first grinding step, and shortens the machining time.

It is a perspective view which shows the grinding apparatus. It is a partial cross-sectional side view which shows a chuck table and a grinding unit. FIG. 3A is a side view showing the chuck table and the grinding unit in the preparation step, and FIG. 3B is a side view showing the chuck table and the grinding unit in the first grinding step. It is a side view which shows the chuck table and the grinding unit in a separation step. FIG. 5A is a side view showing the chuck table and the grinding unit in the second grinding step, and FIG. 5B is a side view showing the chuck table and the grinding unit after grinding the workpiece.

Hereinafter, embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of a grinding device that can be used in the method for grinding a workpiece according to the present embodiment will be described. FIG. 1 is a perspective view showing the grinding device 2. In FIG. 1, the X-axis direction (first machining feed direction, front-rear direction, first horizontal direction) and the Y-axis direction (left-right direction, second horizontal direction) are directions perpendicular to each other. The Z-axis direction (second machining feed direction, vertical direction, vertical direction, height direction) is a direction perpendicular to the X-axis direction and the Y-axis direction.

The grinding device 2 includes a base 4 that supports or accommodates each component constituting the grinding device 2. A rectangular opening 4a whose longitudinal direction is along the X-axis direction is formed on the upper surface side of the base 4. Further, at the rear end portion of the base 4, a rectangular parallelepiped support structure 6 projecting upward from the upper surface of the base 4 is provided along the Z-axis direction.

A first moving mechanism (first moving unit) 8 is provided inside the opening 4a. For example, the first moving mechanism 8 is a ball screw type moving mechanism, which is a pair of guide rails (not shown) arranged along the X-axis direction and a flat plate shape slidably mounted on the pair of guide rails. It is equipped with a moving table (not shown). A nut portion is provided on the back surface (lower surface) side of the moving table, and a ball screw (not shown) arranged along the X-axis direction is screwed into the nut portion between the pair of guide rails. ing. A pulse motor (not shown) is connected to the end of the ball screw. When the ball screw is rotated by the pulse motor, the moving table moves along the pair of guide rails in the X-axis direction.

A chuck table (holding table) 10 for holding the workpiece 11 is provided on the surface (upper surface) side of the moving table of the first moving mechanism 8. Further, the first moving mechanism 8 includes a table cover 8a provided so as to surround the chuck table 10. Further, a bellows-shaped dust-proof / drip-proof cover 12 that can be expanded and contracted along the X-axis direction is provided in front of and behind the table cover 8a. The table cover 8a and the dust-proof / drip-proof cover 12 cover the components (guide rail, moving table, ball screw, pulse motor, etc.) of the first moving mechanism 8 arranged inside the opening 4a.

The upper surface of the chuck table 10 is a flat surface formed substantially parallel to the X-axis direction and the Y-axis direction, and constitutes a holding surface 10a for holding the workpiece 11. The holding surface 10a is made of a porous member such as porous ceramics, and is a suction source such as an ejector via a flow path (not shown), a valve (not shown), or the like formed inside the chuck table 10. It is connected to (not shown). Note that FIG. 1 shows an example in which the holding surface 10a is formed in a circular shape on the assumption that the disk-shaped workpiece 11 is held, but the shape of the holding surface 10a is appropriately determined according to the shape of the workpiece 11 and the like. Can be changed.

The chuck table 10 moves along the X-axis direction together with the table cover 8a by the first moving mechanism 8. Further, a rotation drive source (not shown) such as a motor is connected to the chuck table 10, and this rotation drive source rotates the chuck table 10 around a rotation axis substantially parallel to the Z-axis direction. That is, the rotation axis of the chuck table 10 is set along the direction perpendicular to the holding surface 10a.

A second moving mechanism (second moving unit) 14 is provided on the front surface side of the support structure 6. The second moving mechanism 14 includes a pair of guide rails 16 arranged along the Z-axis direction. A flat plate-shaped moving table 18 is slidably mounted on the pair of guide rails 16 along the pair of guide rails 16.

A nut portion (not shown) is provided on the rear surface side (rear surface side) of the moving table 18, and the ball screw 20 arranged along the Z-axis direction between the pair of guide rails 16 is provided on the nut portion. Is screwed in. Further, a pulse motor 22 is connected to the end of the ball screw 20. When the ball screw 20 is rotated by the pulse motor 22, the moving table 18 moves in the Z-axis direction along the pair of guide rails 16.

A support member 24 projecting forward from the front surface of the moving table 18 is fixed to the front side (front side) of the moving table 18. The support member 24 supports the grinding unit 26 that grinds the workpiece 11. The movement (elevation) of the grinding unit 26 in the Z-axis direction is controlled by the second movement mechanism 14.

The grinding unit 26 includes a hollow cylindrical housing 28 supported by a support member 24. The housing 28 houses a columnar spindle 30 arranged along the Z-axis direction. The tip end portion (lower end portion) of the spindle 30 projects downward from the lower surface of the housing 28. Further, a rotation drive source (not shown) such as a motor is connected to the base end portion (upper end portion) of the spindle.

A disk-shaped wheel mount 32 is fixed to the tip of the spindle 30. Then, a grinding wheel 34 for grinding the workpiece 11 is mounted on the lower surface side of the wheel mount 32. For example, the grinding wheel 34 is fixed to the wheel mount 32 by a fixing tool such as a bolt.

The grinding wheel 34 includes an annular base 36 made of metal or the like and having a diameter substantially the same as that of the wheel mount 32. Further, a plurality of grinding wheels 38 are fixed to the lower surface side of the base 36. For example, the plurality of grinding wheels 38 are formed in a rectangular parallelepiped shape and are arranged at substantially equal intervals along the outer periphery of the base 36.

The grinding wheel 38 is formed by fixing abrasive grains made of diamond, cBN (Cubic Boron Nitride) or the like with a binder such as a metal bond, a resin bond or a vitrified bond. However, the material, shape, size, etc. of the grinding wheel 38 are not limited, and the number of grinding wheels 38 fixed to the base 36 can be arbitrarily set.

The grinding wheel 34 rotates around a rotation axis substantially parallel to the vertical direction by the power transmitted from the rotation drive source via the spindle 30 and the wheel mount 32. That is, the rotation axis of the grinding wheel 34 is set along the direction perpendicular to the holding surface 10a of the chuck table 10. Further, inside or in the vicinity of the grinding unit 26, there is a grinding fluid supply path such as a nozzle that supplies a liquid (grinding fluid) such as pure water to the workpiece 11 held by the chuck table 10 and the grinding wheel 38. (Illustrated) is provided.

A control unit (control unit, control device) 40 for controlling the grinding device 2 is provided inside or outside the grinding device 2. The control unit 40 is connected to each component of the grinding device 2 (first moving mechanism 8, chuck table 10, second moving mechanism 14, grinding unit 26, etc.), and is for controlling the operation of each component. Generate a control signal.

For example, the control unit 40 is composed of a computer and stores a processing unit that performs processing such as calculations necessary for controlling the grinding device 2 and various information (data, programs, etc.) used for controlling the grinding device 2. It has a part. The processing unit includes a processor such as a CPU (Central Processing Unit). Further, the storage unit includes a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

The workpiece 11 is ground by the above-mentioned grinding device 2. For example, the workpiece 11 is a disk-shaped wafer made of a semiconductor such as silicon, and includes a front surface 11a and a back surface 11b. Further, the workpiece 11 is divided into a plurality of rectangular regions by a plurality of streets (scheduled division lines) arranged in a grid pattern so as to intersect each other. Devices (not shown) such as ICs (Integrated Circuits), LSIs (Large Scale Integration), and LEDs (Light Emitting Diodes) are located in each of the plurality of regions of the workpiece 11 partitioned by the streets on the surface 11a side. It is formed.

By dividing the workpiece 11 along the street by cutting, laser processing, or the like, a plurality of device chips each including a device are manufactured. Further, if the back surface 11b side of the workpiece 11 is ground using the grinding device 2 to thin the workpiece 11 before the workpiece 11 is divided, a thin device chip can be obtained.

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

For example, the workpiece 11 is arranged on the chuck table 10 so that the front surface 11a side faces the holding surface 10a and the back surface 11b side is exposed upward. When the negative pressure of the suction source is applied to the holding surface 10a in this state, the workpiece 11 is sucked and held by the chuck table 10. A protective tape made of resin or the like and protecting the surface 11a side (device or the like) of the workpiece 11 may be attached to the surface 11a side of the workpiece 11. In this case, the workpiece 11 is held by the holding surface 10a of the chuck table 10 via the protective tape.

FIG. 2 is a partial cross-sectional side view showing the chuck table 10 and the grinding unit 26. The holding surface 10a of the chuck table 10 is formed in a conical shape with the center of the holding surface 10a as the apex, and is slightly inclined with respect to the radial direction of the holding surface 10a. Therefore, the workpiece 11 is held in a slightly deformed state along the holding surface 10a. The chuck table 10 is arranged in a slightly tilted state so that the region 10b on the rear end side (support structure 6 side) of the holding surface 10a is parallel to the lower surface of the grinding wheel 38.

Although the inclination of the holding surface 10a is exaggerated in FIG. 2 for convenience of explanation, the actual inclination of the holding surface 10a is small. For example, when the diameter of the holding surface 10a is about 290 mm or more and 310 mm or less, the difference between the height position of the center of the holding surface 10a and the height position of the outer peripheral edge of the holding surface 10a (corresponding to the height of the cone). Is set to about 20 μm or more and 40 μm or less.

The workpiece 11 held by the chuck table 10 is ground and thinned by the grinding wheel 38 of the grinding wheel 34. Further, during the grinding of the workpiece 11, the grinding fluid is supplied to the workpiece 11 and the grinding wheel 38. As a result, the workpiece 11 and the grinding wheel 38 are cooled, and the debris (machined debris) generated by the processing is washed away.

Here, in the present embodiment, creep feed grinding is performed in which the chuck table 10 and the grinding wheel 34 are relatively moved along a direction parallel to the holding surface 10a of the chuck table 10 to process the workpiece 11. The workpiece 11 is processed by in-feed grinding in which the chuck table 10 and the grinding wheel 34 are relatively moved along a direction perpendicular to the holding surface 10a of the chuck table 10 to machine the workpiece 11. To dilute. Hereinafter, a specific example of a method of grinding a workpiece using the grinding device 2 will be described.

First, the positional relationship between the chuck table 10 and the grinding unit 26 is adjusted (preparation step). FIG. 3A is a side view showing the chuck table 10 and the grinding unit 26 in the preparation step. In the preparation step, the grinding wheel 38 is positioned on the outer side in the radial direction of the holding surface 10a, and the lower surface of the grinding wheel 38 is positioned downward by a predetermined distance from the upper surface (back surface 11b) of the workpiece 11 held by the chuck table 10. The positions of the chuck table 10 and the grinding unit 26 are adjusted so that they can be positioned.

Specifically, the position of the chuck table 10 in the X-axis direction is set so that the workpiece 11 is arranged in front of the grinding wheel 34 (on the left side of the paper surface in FIG. 3A) without overlapping with the grinding wheel 34. It is controlled by the first moving mechanism 8 (see FIG. 1). Further, the position of the grinding unit 26 in the Z-axis direction is controlled by the second moving mechanism 14 (see FIG. 1) so that the lower surface of the grinding wheel 38 is positioned below the back surface 11b of the workpiece 11.

At this time, the difference ΔH between the height position (position in the Z-axis direction) between the back surface 11b of the workpiece 11 and the lower surface of the grinding wheel 38 is the grinding amount (before and after grinding) of the workpiece 11 in the first grinding step described later. Corresponds to the target value (difference in thickness of the workpiece 11). When the workpiece 11 is a silicon wafer, for example, the value of ΔH is set to about 10 μm.

Next, while rotating the chuck table 10 and the grinding wheel 34, the chuck table 10 and the grinding unit 26 are relatively moved along the direction parallel to the holding surface 10a, and the workpiece 11 is moved by the grinding wheel 38. Grind from the outer periphery to the center (first grinding step). FIG. 3B is a side view showing the chuck table 10 and the grinding unit 26 in the first grinding step.

In the first grinding step, the workpiece 11 is ground by creep feed grinding. Specifically, first, the chuck table 10 and the grinding wheel 34 are rotated around a rotation axis substantially perpendicular to the holding surface 10a of the chuck table 10, respectively. For example, the rotation speed of the chuck table 10 is set to 300 rpm, and the rotation speed of the grinding wheel 34 is set to 2000 rpm or more and 3000 rpm or less.

Then, with the chuck table 10 and the grinding wheel 34 rotated, the chuck table 10 is moved toward the grinding wheel 34 along the X-axis direction (first machining feed). As a result, the chuck table 10 and the grinding wheel 34 approach each other along the direction parallel to the holding surface 10a of the chuck table 10. The moving speed (machining feed speed) of the chuck table 10 is set to, for example, 5 mm / s.

When the chuck table 10 moves and the outer peripheral edge of the workpiece 11 reaches the front end (the left end of the paper surface in FIG. 3B) of the moving path (rotation path) of the grinding wheel 38, the outer peripheral portion of the workpiece 11 is ground. It is scraped off by the grindstone 38. At this time, since the workpiece 11 rotates together with the chuck table 10, the entire outer peripheral portion of the workpiece 11 comes into contact with the grinding wheel 38 and is ground in an annular shape.

Then, the chuck table 10 moves along the X-axis direction until the center of the workpiece 11 is arranged at a position where it overlaps with the front end of the movement path of the grinding wheel 38. As a result, the workpiece 11 is ground from the outer peripheral edge to the center, and the entire workpiece 11 is thinned.

As described above, in the present embodiment, creep feed grinding is performed while rotating the chuck table 10. In this case, when the center of the workpiece 11 reaches directly below the front end of the moving path of the grinding wheel 38, the entire grinding of the workpiece 11 is completed. Therefore, it is not necessary to move the chuck table 10 until the entire workpiece 11 passes directly under the front end of the moving path of the grinding wheel 38, and the moving distance of the chuck table 10 is significantly shortened. As a result, the time required for grinding the workpiece 11 is reduced, and the processing efficiency is improved.

Next, the chuck table 10 and the grinding unit 26 are relatively moved along the direction perpendicular to the holding surface 10a, and the workpiece 11 and the grinding wheel 38 are separated from each other (separation step). FIG. 4 is a side view showing the chuck table 10 and the grinding unit 26 in the separation step.

In the separation step, the grinding unit 26 is slightly raised by the second moving mechanism 14 (see FIG. 1) to separate the grinding wheel 38 from the workpiece 11. As a result, friction does not temporarily act between the workpiece 11 and the grinding wheel 38, and the workpiece 11 and the grinding wheel 38 are cooled. As a result, processing defects such as surface burning of the workpiece 11 are prevented. Further, in the second grinding step described later, the grinding wheel 38 comes into contact with the workpiece 11 again from a state of being separated from the workpiece 11. At this time, wear on the lower surface side of the grinding wheel 38 is promoted, and the condition of the grinding wheel 38 is adjusted.

In the separation step, it is preferable to maintain the rotation of the chuck table 10 and the grinding wheel 34. As a result, after the separation step is performed, it is possible to smoothly shift to the second grinding step described later.

However, if the grinding of the workpiece 11 is not hindered, the separation step may be omitted. For example, when the workpiece 11 is a member that can be easily ground (such as a silicon wafer), surface burning and grinding defects are unlikely to occur, so that the workpiece 11 can be normally ground even if the separation step is omitted. Easy to do. In this case, the second grinding step described later is started while the height position of the grinding unit 26 at the end of the first grinding step is maintained.

Here, in the above-mentioned first grinding step, the grinding wheel 38 may be worn while the workpiece 11 is ground from the outer peripheral edge to the center, and the height position of the lower surface of the grinding wheel 38 may fluctuate. In this case, the amount of grinding of the workpiece 11 varies between the early stage of grinding (grinding the outer peripheral portion of the workpiece 11) and the final stage (grinding of the central portion of the workpiece 11), and the workpiece after grinding varies. The thickness of 11 may vary. For example, when a silicon wafer is ground in the first grinding step, the central portion of the silicon wafer is thicker than the outer peripheral portion by about 1 μm.

Therefore, in the present embodiment, after the first grinding step is performed (in the case where the separation step is performed, after the separation step is performed), the chuck table 10 and the grinding wheel 34 are ground while being rotated. The unit 26 is relatively moved along a direction perpendicular to the holding surface 10a, and the workpiece 11 is ground with a grinding wheel 38 until it reaches a predetermined finishing thickness (second grinding step). FIG. 5A is a side view showing the chuck table 10 and the grinding unit 26 in the second grinding step.

In the second grinding step, the workpiece 11 is ground by in-feed grinding. Specifically, the grinding unit 26 is lowered along the Z-axis direction by the second moving mechanism 14 (see FIG. 1) while maintaining the rotation of the chuck table 10 and the grinding wheel 34 (second machining feed). As a result, the chuck table 10 and the grinding wheel 34 approach each other along the direction perpendicular to the holding surface 10a of the chuck table 10.

The descending speed (machining feed rate) of the grinding unit 26 is set to, for example, 0.2 μm / s or more and 1 μm / s or less. Further, the rotation speeds of the chuck table 10 and the grinding wheel 34 may be the same as or different from those in the first grinding step.

When the lower surface of the grinding wheel 38 reaches the upper surface (back surface 11b) of the workpiece 11, the back surface 11b side of the workpiece 11 is scraped off by the grinding wheel 38, and the workpiece 11 is thinned. At this time, since the entire area on the back surface 11b side of the workpiece 11 is gradually ground by the grinding wheel 38 at the same time, the amount of grinding in each region of the workpiece 11 is unlikely to differ. As a result, the variation in the thickness of the workpiece 11 after grinding is reduced.

Grinding of the workpiece 11 is continued until the thickness of the workpiece 11 reaches a predetermined finish thickness. FIG. 5B is a side view showing the chuck table 10 and the grinding unit 26 after grinding the workpiece 11. When the grinding of the workpiece 11 is completed, the grinding unit 26 rises to separate the workpiece 11 from the grinding wheel 38, and the rotation of the chuck table 10 and the grinding wheel 34 is stopped.

Grinding of the workpiece 11 using the grinding device 2 as described above is realized by controlling the operation of each component of the grinding device 2 by the control unit 40 (see FIG. 1). Specifically, in the storage unit of the control unit 40, each component (first moving mechanism 8, chuck table) of the grinding device 2 necessary for carrying out the preparation step, the first grinding step, the separation step, and the second grinding step is stored. 10. A program that describes a series of operations of the second moving mechanism 14, the grinding unit 26, etc.) is stored. Then, when grinding the workpiece 11 is executed, the control unit 40 reads a program from the storage unit and executes it, and outputs a control signal to each component of the grinding device 2. As a result, the operation of the grinding device 2 is controlled, and the method of grinding the workpiece according to the present embodiment is automatically carried out.

As described above, in the method for grinding a workpiece according to the present embodiment, the first grinding step (creep feed grinding) in which the chuck table 10 and the grinding unit 26 are relatively moved along a direction parallel to the holding surface 10a. However, this is carried out in a state where the chuck table 10 is rotated. As a result, the machining feed distance can be shortened and the machining time can be shortened.

Further, in the method for grinding a workpiece according to the present embodiment, a second grinding step (in-feed grinding) in which the chuck table 10 and the grinding unit 26 are relatively moved along a direction perpendicular to the holding surface 10a is provided. It is carried out continuously after the first grinding step. This eliminates the need for a step of performing creep feed grinding again in order to adjust the thickness of the workpiece 11 after the first grinding step, and shortens the machining time.

When the amount of grinding of the workpiece 11 is large, in-feed grinding may be performed after performing creep-feed grinding a plurality of times. In this case, after the first first grinding step is completed, the chuck table 10 is positioned so that the lower surface of the grinding wheel 38 is positioned below a predetermined distance from the upper surface (back surface 11b) of the work piece 11 after grinding. And the position of the grinding unit 26 is adjusted again (second preparation step). After that, the chuck table 10 is moved along the X-axis direction, and the workpiece 11 is ground again by creep feed grinding (second first grinding step).

Then, after the preparation step and the first grinding step are repeated a plurality of times as described above, in-feed grinding is performed (second grinding step), and the thickness of the workpiece 11 is made uniform. The number of preparation steps and the first grinding step is not limited, and is appropriately set according to the material, thickness, and the like of the workpiece 11.

In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented as long as they do not deviate from the scope of the object of the present invention.

11 Work piece 11a Front surface 11b Back surface 2 Grinding device 4 Base 4a Opening 6 Support structure 8 1st moving mechanism (1st moving unit)
8a Table cover 10 Chuck table (holding table)
10a Holding surface 10b Area 12 Dust-proof and drip-proof cover 14 Second movement mechanism (second movement unit)
16 Guide rail 18 Moving table 20 Ball screw 22 Pulse motor 24 Support member 26 Grinding unit 28 Housing 30 Spindle 32 Wheel mount 34 Grinding wheel 36 Base 38 Grinding wheel 40 Control unit (control unit, control device)

Claims (2)

It is a grinding method of a workpiece that grinds the workpiece using a grinding device.
The grinding device is
A chuck table having a holding surface for holding the workpiece and having a rotation axis set along a direction perpendicular to the holding surface.
A grinding wheel including a grinding wheel arranged in an annular shape is mounted, and a grinding unit for grinding the workpiece with the grinding wheel is provided.
The chuck table and the chuck table so that the grinding wheel is positioned outside the holding surface and the lower surface of the grinding wheel is positioned a predetermined distance below the upper surface of the workpiece held by the chuck table. Preparation steps to adjust the positional relationship with the grinding unit,
After performing the preparation step, while rotating the chuck table and the grinding wheel, the chuck table and the grinding unit are relatively moved along a direction parallel to the holding surface, and the grinding wheel is used. The first grinding step, which grinds the workpiece from the outer peripheral edge to the center,
After performing the first grinding step, the chuck table and the grinding unit are relatively moved along the direction perpendicular to the holding surface while the chuck table and the grinding wheel are rotated, and the grinding is performed. A method for grinding a workpiece, which comprises a second grinding step of grinding the workpiece to a predetermined finish thickness with a grindstone. After the first grinding step and before the second grinding step, the chuck table and the grinding unit are relatively moved along the direction perpendicular to the holding surface, and the workpiece is processed. The method for grinding a workpiece according to claim 1, further comprising a separation step for separating the grinding wheel and the grinding wheel from each other.

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