JPH0555267B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cleaning method and a cleaning device for a porous chuck table that is mounted on a grinding machine and holds a workpiece by suction.

[Conventional technology]

A grinding machine for grinding a workpiece such as a wafer is equipped with a chuck table, and the workpiece is held by suction on the chuck table to grind the workpiece.

FIG. 7 shows an example of a grinding machine equipped with a chuck table. In the figure, a turntable 2 is rotatably disposed on a bed base 1, and a pair of chuck tables 3a and 3b are rotatably disposed on the surface of the turntable 2. In the figure, reference numeral 4 denotes a head that is mounted on the bed base 1 so as to be movable up and down.A rotatable spindle 5 is vertically attached to the head 4, and a grindstone 6 is fixed to the lower end of the spindle 5. There is. 7 is a wafer as a workpiece that is held by chuck tables 3a and 3b; 8 is a brush that reciprocates and rotates in the direction of the arrow;
0 is a transfer arm that sucks the wafer 7 with a suction cup 11 and transports the wafer 7 along the rail 12.

When grinding the wafer 7 using this type of grinding machine, the following procedure is followed.

First, loading (not shown)
A wafer 7 brought in by a suction cup 1
1, and is transported to a predetermined position on the chuck table 3a by the transfer arm 10 and placed there. At this stationary position, the wafer 7 is held by suction on the chuck table 3a.

Next, the turntable 2 is rotated 180 degrees, the wafer 7 is moved to the grindstone 6 side, and the wafer 7 is ground by rotation of the grindstone 6. During this grinding, a wafer 7 to be processed next is similarly held by suction on the chuck table 3b. When the grinding of the wafer 7 is completed, the turntable 2 is rotated 180 degrees again, and the wafer 7 on the chuck table 3b is ground, while the wafer 7 after the grinding is transferred from the chuck table 3a to the transfer arm 10. and is transported to an unloading means (not shown). After the wafer 7 is removed from the chuck table 3a, a cleaning liquid such as water is applied to the surface of the chuck table 3a by a cleaning liquid supply means (not shown), and the brush 8 is rotated to remove the chuck table 3a. cleaning of the surface is carried out. In this way, by repeating the procedure from placing the wafer 7 on the chuck table to removing the wafer 7 and cleaning the chuck table surface, the wafer 7 is ground and the chuck table is cleaned one after another. It is carried out in

Incidentally, chuck tables 3a and 3b used in this type of grinding machine used to have a metal base 13 with a plurality of vacuum suction holes 14, as shown in FIG. . However, when the chuck tables 3a and 3b are used to hold the wafer 7 by suction using the vacuum suction hole 14, local suction force acts on the vacuum suction hole 14, so that the vacuum suction hole An inconvenience occurred in that the shape of the hole 14 was transferred onto the surface of the wafer 7. In recent years, in order to avoid such inconveniences, porous chuck tables have been used in which a porous member having numerous holes formed therein is disposed on the front surface of the chuck table. If this porous chuck table is used, the wafer 7 is sucked using the countless holes in the porous member, so the suction force acts uniformly on the surface of the wafer 7, and the hole shape is transferred to the surface of the wafer 7. The above-mentioned inconvenience of being left behind will be resolved.

[Problem to be solved by the invention]

However, since the porous chuck table has countless minute holes on its surface, it is easy for grinding debris to get into these holes. Even if you rub it, it is difficult to completely remove it. As a result, the porous chuck table (more specifically, the porous member) becomes clogged and the vacuum suction force is weakened, resulting in incomplete holding of the wafer 7, and some of the grinding debris that has entered the holes in the porous member. It protrudes from the surface of the chuck table and hits the surface of the wafer 7,
A new problem has come to light: a crack occurs in the wafer 7 from the contact area.

The present invention has been made to solve the above problems, and its purpose is to eliminate the grinding debris protruding from the surface of the chuck table (porous member) even if the grinding debris enters the hole of the chuck table (porous member). An object of the present invention is to provide a method for cleaning a porous chuck table that can be effectively removed, and a cleaning device therefor.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the cleaning method of the present invention
In a method for cleaning a porous chuck table that suctions and holds a workpiece to be ground by a grindstone,
After the workpiece is removed from the surface of the porous chuck table after grinding is completed, cleaning fluid is supplied from the bottom side of the porous member to the surface side of the porous chuck table to remove the grinding debris that has entered the holes of the porous member. The grinding wheel is ejected to the surface side, and the grindstone member is pressed against the surface of the porous chuck table to rub it, thereby removing the grinding debris protruding from the holes of the porous member to the surface. The apparatus of the present invention also includes a cleaning fluid supply means for supplying cleaning fluid to the bottom side of the porous member in the porous chuck table, a grindstone member disposed on the surface side of the porous chuck table, and a porous chuck of the grindstone member. The present invention is characterized by having a grindstone member drive mechanism that performs pressing drive against the surface of the grinding table and drive for releasing the pressure.

[Effect]

In the present invention configured as above,
By driving the cleaning fluid supply means to supply cleaning fluid from the bottom side of the porous member in the porous chuck table, the cleaning fluid is ejected to the surface side through numerous holes (porous holes) in the porous member. This jetting causes the grinding debris that has entered the holes of the porous member to be discharged from the porous holes and flowed out together with the cleaning fluid.

Furthermore, even if some grinding debris protruding from the porous holes to the surface remains, the protruding portion of the grinding debris will drive the grindstone member drive mechanism to press the grindstone member against the surface of the porous chuck table and rub it. As a result, it is removed. In this way, in the present invention, the cleaning of the porous chuck table surface is achieved through the cooperation of the cleaning fluid supply action and the removal action of the grindstone member.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows an embodiment of a cleaning device according to the present invention. In the figure, a porous chuck table 3 is rotatably mounted on the turntable 2 of the grinding machine shown in FIG. This porous chuck table 3 is made by integrally connecting a passage forming base 15 and a porous accommodation base 16, and the passage forming base 15 has a vacuum suction passage and a cleaning fluid supply passage 17 inside. is formed. The vacuum suction passage and the cleaning fluid supply passage 17 may be formed independently as separate passages, or one passage may be formed and used for both vacuum suction and cleaning fluid supply as appropriate. You may also do so. The cleaning fluid supply passage 17 is branched into a plurality of passages at the inlet side 17a,
The exit side of each branch passage is a porous accommodation base 16.
It faces the bottom side. Further, an inlet side 17a of the passage 17 communicates with a pump 18 for supplying cleaning fluid.

The porous accommodating base 16 has a counterbore-shaped recess formed in the center of the front side, and the porous member 20 is accommodated in this recess. The porous member 20 is made of a member such as vitrified, and has countless pores (porous pores) formed on the surface and inside thereof like a sponge. A plurality of through holes 21 communicating with the cleaning fluid supply passage 17 (specifically, each branch passage thereof) are formed in the bottom wall of the base 16, and the cleaning fluid supplied from the pump 18 is passed through the passage 17 and the through holes. 21 to the bottom side of the porous member 20. These, the through hole 21 and the cleaning fluid supply passage 1
7, the pump 18, and the control device 22 that controls the operation of the pump 18 constitute a first cleaning fluid supply means. Note that the cleaning fluid may be a gas such as air, a liquid such as water, or a mixture of these gases and liquids, and the type of the cleaning fluid is arbitrarily set according to specifications.

On the other hand, near the surface of the porous chuck table 3, a spray nozzle 23 for spraying a cleaning fluid such as water as a cleaning fluid is arranged with its jetting surface facing the surface of the chuck table 3. The flow path of the injection nozzle 23 communicates with the discharge port of a pump 24, and by driving the pump 24, the cleaning water is sprayed onto the surface of the porous chuck table 3. The operation of the pump 24 is controlled by the control device 22, and these injection nozzles 23, pump 24, and control device 22 are as follows:
A second cleaning fluid supply means is configured.

Further, near the surface side of the porous chuck table 3, an oil stone device 25 is arranged as a table rubbing device. This oil stone device 25 has an oil stone 26 as a grindstone member.
, a frame 27 that accommodates this oil stone 26, and a holding frame 28 that loosely fits this frame 27.
The base end side of the frame body 27 is rotatably supported on the holding frame 28 by a pin 30.
A spring 31 is interposed between the distal end side of the frame body 27 and the holding frame 28, which always urges the oil stone 26 forward (in the direction of the porous chuck table).

This oil stone device 25 is held by an oil stone drive mechanism 32 which serves as a grindstone member drive mechanism that presses and drives the oil stone 26 against the surface of the porous chuck table 3.

Although various other configurations are possible for the oil stone drive mechanism 32, in this embodiment, the drive mechanism 32 is configured using a cylinder device 33.

That is, in FIG. 1, the oil stone drive mechanism 32 includes a cylinder device 33 and an operating rod 34.
The main elements are a holding arm 35, a cylinder shaft portion 36, and a control device 22 that controls the operation of the cylinder device 33. The cylinder device 33 is fixed to the bed base 1 of the grinding machine via an arm 37, etc., and the cylinder rod 38 and the tip of the operating rod 34 are connected by a coupling 40. Further, one end of a transmission arm 44 is connected to the base end of the actuating rod 34 by a pin, and the other end of the transmission arm 44 and the base end of the holding arm 35 are fixed to the cylindrical shaft portion 36. .
This cylindrical shaft portion 36 is fitted onto a shaft 41 and is rotatable about the shaft 41 as a fulcrum. An oil stone device 25 is provided at the tip of the holding arm 35.
A holding frame 28 is fixed.

The cleaning device of this embodiment is constructed as described above, and a method of cleaning a porous chuck table using the same device will be explained below along with the operation of the device.

First, when cleaning the surface of the porous chuck table 3, the wafer 7 that has been completely ground is removed from the porous chuck table 3 by the transfer arm 10, as described in FIG. After removing the wafer 7, the pump 24 is activated while the porous chuck table 3 is rotated, and the cleaning liquid is sprayed from the spray nozzle 23 toward the surface of the table 3.

On the other hand, the cylinder device 33 is driven and the first
In the state shown in the figure, raise the cylinder rod 38.
As the rod 38 rises, the cylindrical shaft portion 36 moves toward the shaft 4.
1 as a fulcrum and rotates counterclockwise. Accordingly, the holding arm 35 whose base end is fixed to the cylinder shaft 36 also rotates counterclockwise, and the oil stone 26 comes into contact with the surface of the porous chuck table 3.

In this case, since the oil stone 26 receives the biasing force of the spring 31 and the rotational force in the counterclockwise direction about the pin 30, the distal end 26a protrudes more inclined forward than the proximal end 26b. ing.
Therefore, the tip side 26a of the oil stone 26 first comes into contact with the surface of the porous chuck table 3, and then as the cylinder rod 38 rises, it gradually comes into contact with the base end side 26b.
Finally, as shown in Figure 2, oil stone 2
The grinding surface of 6 uniformly contacts the surface of the table 3.

If the porous chuck table 3 is rotated in this contact state, as shown in FIG. It is scraped off, and the shavings are washed out with a cleaning solution.

In this embodiment, when cleaning the porous chuck table 3, the pump 18 is further activated, and the cleaning fluid is supplied to the lower surface (bottom surface) of the porous member 20 through the cleaning fluid supply passage 17 and the through hole 21.
Supplied on the side. This cleaning fluid is applied to the porous member 2.
It is transmitted through the porous holes 42 inside the 0 and ejected to the surface side. The fine grinding debris that has entered the porous hole 42 due to the jet of cleaning fluid is jetted out to the surface side, and the jetted grinding debris is flowed out to the outside by the cleaning fluid. .

In this manner, in this embodiment, the jetting action of the cleaning fluid, the scraping action of the grinding debris by the oil stone 26, and the outflowing action of the cleaning fluid cooperate to provide an effective removal action of the grinding debris. Note that the cleaning fluid is sprayed from the oil stone 26.
It may be done before grinding the oil stone 26, or it may be done simultaneously with the grinding of the oil stone 26.
It may be carried out continuously before and after grinding. When cleaning of the porous chuck table 3 is completed, the cylinder device 33 is advanced and the cylinder rod 38 is moved downward. Therefore,
The holding arm 35 rotates clockwise, and the pressing operation of the oil stone 26 is released. and,
The oil stone 26 returns to its original position (the state shown in FIG. 1) and is ready for the next cleaning.

FIGS. 4 and 5 show other configuration examples of the oil stone drive mechanism. In the description of the configuration examples shown in FIGS. 4 and 5, the same parts as those shown in FIG.

The device shown in FIGS. 4 and 5 is configured so that the oil stone 26 can be rotated in the front and back direction by rotating the frame 27 about the pin 30, similar to the device shown in FIG. 1. However, a distinctive feature different from the device shown in FIG. 1 is that the oil stone 26 is configured to be able to rotate in the left-right direction and move in the front-back direction.

That is, a box-shaped cylinder 45 is fixed to the lower surface of the holding arm 35, and a piston 46 is slidably housed within the cylinder 45.
The shaft portion of the piston 46 passes through both front and rear end walls of the cylinder 45 in an airtight and slidable manner and protrudes outward, and its protruding tip portion is pivotally supported by the holding frame 28 . Therefore, the piston 46 functions as a rotation axis for rotating the holding frame 28 in the left-right direction, and as the cylinder rod 38 rises, the holding arm 35 rotates counterclockwise to rotate the oil stone 26. When the tip 26a contacts the porous chuck table 3, the oil stone 26 rotates back and forth (more specifically, clockwise) using the pin 30 as a fulcrum, and further rotates left and right (as shown in the figure) using the piston 46 as a fulcrum. While rotating in the A direction), it comes into contact with the surface of the porous chuck table 3. By applying the horizontal rotation of the oil stone 26 in this way, the bottom surface (ground surface) of the oil stone 26 comes into contact with the surface of the porous chuck table 3 in a more familiar state.
The sliding action of the table 3 can be performed more effectively.

Furthermore, since the oil stone 26 is fixed to the piston 46 via the frame 27 and the holding frame 28, for example, if working fluid is supplied into the cylinder 45 from the working hole 47, the fluid pressure will Then, the piston 46 slides forward, and conversely, when working fluid is supplied into the cylinder 45 from the working hole 48 on the opposite side, the piston 46 slides backward. That is, by sequentially switching the flow path of the working fluid supplied into the cylinder 45, the piston 46 slides in the front-rear direction, and the oil stone 26 also moves in the front-rear direction in conjunction with the piston 46.

If the oil stone 26 is moved back and forth when it is rubbed against the porous chuck table 3, the rubbing action can be performed more effectively, and the cleaning effect of the table 3 can be greatly enhanced.

Note that the present invention is not limited to the above-mentioned embodiments, and can take various embodiments. For example, in this embodiment, the vertical movement of the actuating rod 34 is converted into the rotational movement of the holding arm 35, and the oil stone 26
The oil stone is pressed against the porous chuck table 3, but instead of this, the oil stone may be directly pressed against the surface of the table 3 by the vertical movement of the actuating rod 34 via a spring or the like.

Furthermore, in FIG. 1, the porous member 20 is fitted over the entire area of the recess space of the porous accommodation base 16, but for example, as shown in FIG. A plurality of partition rings 44 made of ceramics or the like may be accommodated, and the porous member 20 may be accommodated in the space between the partition rings 44. This table has independent suction areas formed by the partition rings 44, and is configured so that the suction areas can be switched arbitrarily by switching the suction passages corresponding to each suction area. ,
Wafers with different diameters can be reliably attracted and held.

Furthermore, although the brush 8 shown in FIG. 7 is omitted in this embodiment, this brush 8 is arranged on the surface side of the porous chuck table 3, and the oil stone 26 and this brush 8 are used together. The surface of the table 3 may also be cleaned using the same method.

Furthermore, in this embodiment, oil stone is used as the whetstone member, but it is not limited to this.
For example, a grindstone formed of abrasive grains such as CBN with a suitable bonding agent such as resin bond may be used.

〔Effect of the invention〕

As explained above, the present invention is capable of spraying microscopic grinding debris that has entered the porous hole of a porous chuck table to the surface using a cleaning fluid that is pressurized from the bottom side, and removing the grinding debris that is protruding from the porous hole. The structure is such that the grinding chips spewed out on the surface and the shavings scraped off by the oil stone are removed by flowing out, so that the grinding chips do not protrude onto the surface of the porous chuck table. The surface of the chuck table can be cleaned evenly. Therefore, when the wafer is adsorbed after cleaning, grinding debris will not locally hit the wafer surface and cause cracks in the wafer.

In addition, the pressurized fluid blows out minute grinding debris that enters the porous holes toward the surface and removes them, so the porous holes do not become clogged and a suitable suction force can be applied to the wafer when it is attracted. .

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram showing the operation of the same embodiment, FIG. 3 is an explanatory diagram showing a state in which grinding debris protrudes into the porous hole, and FIG. 4 is a perspective view showing another example of the configuration of the oil stone drive mechanism. FIG. 5 is a sectional view of the oil stone device shown in FIG. 4, FIG. 6 is a diagram of another aspect of the porous chuck table, and FIG. 7 is a plan view showing an example of a grinding machine equipped with a brush cleaning device.
FIG. 8 is a sectional view showing the structure of a former chuck table. 1... Bed base, 2... Turntable, 3
...Porous chuck table, 3a, 3b...
Chuck table, 4...Head, 5...Spindle, 6...Wheelstone, 7...Wafer, 8...Brush, 10...Transfer arm, 11...Sucker, 12...Rail, 13...Metal Base, 14...
...Vacuum suction hole, 15...Passage forming base, 16...
Porous accommodation base, 17...Cleaning fluid supply passage,
17a...Inlet side, 18...Pump, 20...Porous member, 21...Through hole, 22...Control device, 23...Injection nozzle, 24...Pump, 25
... Oil stone device, 26 ... Oil stone, 27 ... Frame, 28 ... Holding frame, 30 ... Pin, 31 ... Spring, 32 ... Oil stone drive mechanism, 33 ... Cylinder device, 34 ... ...Operating rod, 35...Holding arm, 36...Cylinder shaft, 37
...Arm, 38...Cylinder rod, 40...
Coupling ring, 41... shaft, 42... porous hole, 43... grinding waste, 44... transmission arm, 4
5...Cylinder, 46...Piston, 47, 48
...Operating hole.

Claims (1)

[Scope of Claims] 1. In a method for cleaning a porous chuck table that suction-holds a workpiece to be ground by a grindstone, the porous chuck table is cleaned after the workpiece after grinding is removed from the surface of the porous chuck table. Cleaning fluid is supplied from the bottom side of the porous member on the chuck table toward the front side to blow out the grinding debris that has entered the holes of the porous member to the surface side, and at the same time, the grinding wheel member is pressed against the surface of the porous chuck table. A method for cleaning a porous chuck table, which comprises rubbing and removing grinding debris protruding from the pores of a porous member to the surface. 2. A cleaning fluid supply means for supplying cleaning fluid to the bottom side of the porous member in the porous chuck table, a grindstone member disposed on the surface side of the porous chuck table, and a press of the grindstone member to the surface of the porous chuck table. A cleaning device for a porous chuck table, comprising: a grindstone member drive mechanism that performs drive and pressure release drive.