JP7610439B2 - Porous Chuck Table - Google Patents

Description

The present invention relates to a porous chuck table.

In processing equipment (machining devices) that process various plate-shaped workpieces such as semiconductor wafers, resin package substrates, glass, and ceramics, a method of suction holding the workpiece using a porous chuck table (see, for example, Patent Document 1) is often used to fix the workpiece. The porous chuck table strongly fixes the workpiece over the entire porous holding surface, and because the suction holes are fine pores, it can be supported by a relatively flat holding surface.

JP 2000-323440 A

Processing equipment such as cutting equipment and grinding equipment uses liquid for processing. The liquid adheres to the workpiece and the protective member (tape or support substrate) that supports the workpiece, and may also adhere to the back side supported by the porous chuck table. However, if the liquid on the back side drips inside the processing equipment or storage cassette during transport, it can adhere to other workpieces and cause water stains and dirt.

For this reason, the processing equipment must be able to remove any liquid on the backside as quickly as possible. In addition, when the protective member is a die attachment film, there is a device that uses a porous chuck table cooled to a temperature below -10 degrees to cool the protective member with the die attachment film attached while expanding it radially, breaking the die attachment film. However, if liquid adheres to the cooled porous chuck table, the liquid on the porous plate will freeze, posing the risk of damaging the porous plate.

Therefore, the object of the present invention is to provide a porous chuck table that can prevent liquid from remaining on the holding surface.

In order to solve the above problems and achieve the object, the porous chuck table of the present invention is a porous chuck table comprising a porous plate constituting a holding surface, and a base having a suction passage communicating with a suction source and applying a negative pressure to the porous plate fitted into a recess, the porous chuck table comprising aggregate, a bond for fixing the aggregate, and pores formed in the gaps between the aggregate and the bond, the aggregate being composed of main coarse particles having a grain size of F80 to F100 as specified in JIS R6000-1 and secondary coarse particles having a grain size of F150 to F220, the ratio of the main coarse particles to the secondary coarse particles being 1:3 to 1:10, the pores formed by the secondary coarse particles sucking in liquid adhering to the holding surface by capillary action, and the pores formed by the main coarse particles ensuring breathability.

The present invention has the effect of preventing liquid from remaining on the holding surface.

FIG. 1 is a perspective view showing an example of the configuration of a processing apparatus including a porous chuck table according to the first embodiment. FIG. 2 is a perspective view illustrating an example of the configuration of the porous chuck table according to the first embodiment. FIG. 3 is a side view, partially in cross section, of the porous chuck table shown in FIG. FIG. 4 is an enlarged cross-sectional view of part IV in FIG. FIG. 5 is a side view, partly in section, showing a state in which the processing apparatus shown in FIG. 1 cuts a workpiece held on a porous chuck table. FIG. 6 is a flowchart showing a method for manufacturing the porous chuck table shown in FIG. 7A to 7C are cross-sectional views that diagrammatically show a forming step in the method for manufacturing the porous chuck table shown in FIG. FIG. 8 is a diagram showing an outline of a firing step in the method for manufacturing the porous chuck table shown in FIG. FIG. 9 is a cross-sectional view showing an outline of a fixing step in the manufacturing method of the porous chuck table shown in FIG. FIG. 10 is a cross-sectional view illustrating a schematic configuration example of an expansion device including a porous chuck table according to the first embodiment. FIG. 11 is a cross-sectional view illustrating a schematic configuration example of a cleaning device including the porous chuck table according to the first embodiment.

The following describes in detail the form (embodiment) for carrying out the present invention with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. The components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Various omissions, substitutions, or modifications of the configuration can be made without departing from the spirit of the present invention.

[Embodiment 1]
A porous chuck table 1 according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a configuration example of a processing device including a porous chuck table according to the first embodiment. Fig. 2 is a perspective view showing a configuration example of a porous chuck table according to the first embodiment. Fig. 3 is a side view showing, in partial cross section, the porous chuck table shown in Fig. 2. Fig. 4 is a cross-sectional view showing an enlarged view of part IV in Fig. 3. Fig. 5 is a side view showing, in partial cross section, a state in which the processing device shown in Fig. 1 cuts a workpiece held on the porous chuck table.

(Workpiece)
The porous chuck table 1 according to the first embodiment constitutes a processing apparatus 100 shown in Fig. 1. In the first embodiment, the processing apparatus 100 shown in Fig. 1 is a cutting apparatus (corresponding to a processing device) that holds a workpiece 200 on the porous chuck table 1 and cuts (corresponding to processing) the workpiece 200. The workpiece 200 to be processed (also called a processing object) by the processing apparatus 100 shown in Fig. 1 is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer, with a substrate 201 made of silicon, sapphire, gallium, or the like.

The workpiece 200 has a surface 202 on which a plurality of mutually intersecting planned division lines 203 are set, and devices 204 are formed in areas partitioned by the planned division lines 203. The devices 204 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integration), or image sensors such as CCDs (Charge Coupled Devices) or CMOSs (Complementary Metal Oxide Semiconductors).

In the first embodiment, as shown in FIG. 1, the workpiece 200 is a disk-shaped plate having a diameter larger than the outer diameter of the workpiece 200, and an annular frame 210 is attached to the outer edge of the adhesive tape 209, which is attached to the back surface 205 behind the front surface 202, and is supported within the opening of the annular frame 210. The workpiece 200 is cut along the intended division lines 203 and divided into individual devices 204. In the present invention, the workpiece 200 may be a rectangular resin package substrate having multiple devices sealed with resin, a ceramic plate, a glass plate, or the like.

(Processing equipment)
In the first embodiment, the processing device 100 is a cutting device that holds the workpiece 200 on a porous chuck table 1 and cuts the workpiece 200 along a planned division line 203 with a cutting blade 121 to divide the workpiece 200 into individual devices 204. As shown in Fig. 1, the processing device 100 includes a porous chuck table 1 that suction-holds the workpiece 200 on a holding surface 21, a cutting unit 120 that is a processing unit that cuts the workpiece 200 held on the porous chuck table 1, an imaging unit 130 that photographs the workpiece 200 held on the porous chuck table 1, and a control unit 160. As shown in Figs. 1 and 3, the processing device 100 is a so-called facing dual type cutting device that includes two cutting units 120, that is, a two-spindle dicer.

As shown in FIG. 3, the processing device 100 also includes a processing feed unit 141, an indexing feed unit 142, a cutting feed unit 143, and a rotational movement unit 144, which move the porous chuck table 1 and the cutting unit 120 relative to each other.

The machining feed unit 141 moves the porous chuck table 1 and the rotational movement unit 144 in the X-axis direction, which is parallel to the horizontal direction, which is the machining feed direction, thereby moving the cutting unit 120 and the porous chuck table 1 relatively along the X-axis direction. The indexing feed unit 142 moves the cutting unit 120 in the Y-axis direction, which is parallel to the horizontal direction, which is the indexing feed direction, and perpendicular to the X-axis direction, thereby moving the cutting unit 120 and the porous chuck table 1 relatively along the Y-axis direction.

The cutting feed unit 143 moves the cutting unit 120 in the Z-axis direction, which is perpendicular to both the X-axis direction and the Y-axis direction, which are the cutting feed directions, thereby moving the cutting unit 120 and the porous chuck table 1 relatively along the Z-axis direction. The rotational movement unit 144 is supported by the processing feed unit 141, supports the porous chuck table 1, and is disposed so as to be freely movable in the X-axis direction together with the porous chuck table 1. The rotational movement unit 144 rotates the porous chuck table 1 around an axis parallel to the Z-axis direction.

The processing feed unit 141, the indexing feed unit 142, and the cutting feed unit 143 each include a well-known ball screw that is rotatable about its axis, a well-known motor that rotates the ball screw about its axis, and a well-known guide rail that supports the porous chuck table 1 or the cutting unit 20 so that it can move freely in the X-axis, Y-axis, or Z-axis directions. The rotation transfer unit 144 also includes a motor that rotates the porous chuck table 1 about its axis.

The porous chuck table 1 holds the workpiece 200 by suction on the holding surface 21. The porous chuck table 1 is rotated around an axis parallel to the Z-axis direction by the rotational movement unit 144. The rotational movement unit 144 and the porous chuck table 1 are moved in the X-axis direction by the processing feed unit 141. A clamp unit 4 that clamps the annular frame 210 is provided around the porous chuck table 1. The configuration of the porous chuck table 1 will be explained later.

The cutting unit 120 is a processing unit in which the cutting blade 121 is attached to the spindle 123 and cuts the workpiece 200 held on the porous chuck table 1. The cutting unit 120 is provided so as to be movable in the Y-axis direction by the indexing feed unit 142 and movable in the Z-axis direction by the incision feed unit 143 with respect to the workpiece 200 held on the porous chuck table 1. As shown in FIG. 3, the cutting unit 120 is provided on the support frame 102 erected from the device main body 101 via the indexing feed unit 142 and the incision feed unit 143. The cutting unit 120 can position the cutting blade 121 at any position on the holding surface 21 of the porous chuck table 1 by the indexing feed unit 142 and the incision feed unit 143.

The cutting unit 120 includes a cutting blade 121, a spindle housing 122 that is movable in the Y-axis and Z-axis directions by an indexing feed unit 142 and a cutting feed unit 143, a spindle 123 that is rotatably mounted on the spindle housing 122 around its axis and has the cutting blade 121 attached to its tip, a spindle motor (not shown) that rotates the spindle 123 around its axis, and a cutting water nozzle 124 that supplies cutting water to the cutting blade 121.

The cutting blade 121 is an extremely thin cutting wheel having a roughly ring shape. The cutting blade 121 is fixed to the tip of the spindle 123. In the first embodiment, the cutting blade 121 is a so-called hub blade that includes a circular base and a circular cutting blade that is disposed on the outer periphery of the circular base and cuts the workpiece 200. The cutting blade is made of abrasive grains such as SiC, alumina, diamond, or CBN (Cubic Boron Nitride), and a bond (binding material) that fixes the abrasive grains such as metal or resin, and is formed to a predetermined thickness. In the present invention, the cutting blade 121 may be a so-called washer blade that is composed only of a cutting blade.

The imaging unit 130 is fixed to the cutting unit 120 so as to move integrally with the cutting unit 120. The imaging unit 130 is equipped with an imaging element that captures an image of the area to be divided of the workpiece 200 held on the porous chuck table 1 before cutting. The imaging element is, for example, a CCD (Charge-Coupled Device) imaging element or a CMOS (Complementary MOS) imaging element. The imaging unit 30 captures the workpiece 200 held on the porous chuck table 1 to obtain an image for performing alignment between the workpiece 200 and the cutting blade 121, and outputs the obtained image to the control unit 160.

The processing device 100 also includes an X-axis position detection unit (not shown) for detecting the position of the porous chuck table 1 in the X-axis direction, a Y-axis position detection unit (not shown) for detecting the position of the cutting unit 120 in the Y-axis direction, and a Z-axis position detection unit for detecting the position of the cutting unit 120 in the Z-axis direction. The X-axis position detection unit and the Y-axis position detection unit can be configured with a linear scale parallel to the X-axis direction or the Y-axis direction, and a reading head. The Z-axis position detection unit detects the position of the cutting unit 120 in the Z-axis direction with motor pulses. The X-axis position detection unit, the Y-axis position detection unit, and the Z-axis position detection unit output the X-axis direction of the porous chuck table 1 and the Y-axis or Z-axis direction position of the lower end of the cutting blade of the cutting unit 120 to the control unit 160.

In addition, in the first embodiment, the positions of the porous chuck table 1 and the cutting unit 120 of the processing device 100 in the X-axis direction, Y-axis direction, and Z-axis direction are determined based on a predetermined reference position (not shown).

The processing device 100 also includes a cassette elevator 151 on which a cassette 150 that contains multiple workpieces 200 before and after cutting is placed and which moves the cassette 150 in the Z-axis direction, a cleaning unit 152 that cleans the workpieces 200 after cutting, and a transport unit (not shown) that moves the workpieces 200 in and out of the cassette 150 and transports the workpieces 200 between the cassette 150, the porous chuck table 1, and the cleaning unit 152.

The control unit 160 also controls each of the components of the processing device 100, causing the processing device 100 to perform processing operations on the workpiece 200. The control unit 160 is a computer having an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input/output interface device. The arithmetic processing device of the control unit 160 performs arithmetic processing according to a computer program stored in the storage device, and outputs control signals for controlling the processing device 100 to each of the components of the processing device 100 via the input/output interface device.

The control unit 160 is connected to a display unit 161, which is composed of a liquid crystal display device or the like that displays the status and images of the processing operation, an input unit 162 that the operator uses to register processing content information, and a notification unit 163 that notifies the operator. The input unit 162 is composed of a touch panel provided on the display unit 161. The notification unit 163 emits at least one of sound and light to notify the operator.

As shown in Figures 1 and 2, the porous chuck table 1 comprises a circular porous plate 2 that constitutes a holding surface 21 that suction-holds the workpiece 200, and a base 3 that surrounds the outer periphery of the porous plate 2.

In the first embodiment, the base 3 is made of a metal such as stainless steel and is formed into a thick disk shape. As shown in FIG. 3, the base 3 is integrally provided with a disk-shaped disk portion 31 whose outer diameter is larger than the workpiece 200, an annular ring portion 32 standing upright from the outer edge of the disk portion 31, and a recess 33 in the center of the upper surface. The base 3 has the disk portion 31 and the annular ring portion 32 arranged coaxially.

The recess 33 has a circular planar shape and an outer diameter larger than that of the workpiece 200. The recess 33 is disposed in a position coaxial with the disk portion 31 and the annular portion 32. The bottom surface 34 of the recess 33 includes a low surface portion 341 provided in the center and a high surface portion 342 surrounding the low surface portion 341 and provided closer to the upper surface 321 of the annular portion 32 than the low surface portion 341.

The base 3 has a disk portion 31 installed on the rotational movement unit 144. The base 3 has a suction passage 35 penetrating the disk portion 31. The suction passage 35 opens to the lower surface portion 341 of the bottom surface 34, communicates with a suction source 5 such as an ejector, and is provided with an on-off valve 36. The base 3 fits the porous plate 2 into the recess 33 to surround the outer edge of the porous plate 2. When the porous plate 2 is fitted into the recess 33 of the base 3, the porous plate 2 comes into contact with the higher surface portion 342, and the upper surface 321 of the annular portion 32 is located on the same plane as the holding surface 21. When the on-off valve 36 opens and negative pressure from the suction source 5 acts on the suction passage 35, the negative pressure from the suction source 5 acts on the porous plate 2 fitted into the recess 33 of the base 3.

The porous plate 2 is formed in a disk shape with an outer diameter larger than that of the workpiece 200 and equal to the inner diameter of the annular portion 32, i.e., the recess 33. The porous plate 2 is fixed in the recess 33, and the lower surface 22 is fixed to the high surface portion 342 of the base 3 with an adhesive (not shown). The upper surface of the porous plate 2 is the holding surface 21 that suction-holds the workpiece 200. The porous plate 2 is fixed to the base 3, and the holding surface 21 is ground to be flat and parallel to the horizontal direction. The holding surface 21 of the porous plate 2 is located on the same plane as the upper surface 321 of the annular portion 32 of the base 3.

The porous plate 2 is connected to the suction source 5 via a suction passage 35 that penetrates the base 3. When the open/close valve 36 is opened and negative pressure is applied from the suction source 5, the porous plate 2 suctions and holds the workpiece 200 on the holding surface 21.

In the first embodiment, as shown in FIG. 4, the porous plate 2 has aggregate 6 in the form of particles, bond 7 that fixes the aggregate 6, and pores 8 formed in the gaps between the aggregate 6 and the bond 7.

Bond 7 is a vitrified bond made of a glass or ceramic material.

The pores 8 are bubbles (holes) that exist within the bond 7, between the bond 7 and the aggregate 6, or between the aggregates 6, and adjacent pores are connected across the retaining surface 21 and the underside 22 of the porous plate 2, providing breathability to the porous plate 2.

The aggregate 6 is composed of main coarse particles 61 having a grain size of F80 to F100 as specified in JIS (Japanese Industrial Standards) R6000-1, and secondary coarse particles 62 having a grain size of F150 to F220. In the first embodiment, the main coarse particles 61 and secondary coarse particles 62 are composed of abrasive grains made of SiC, alumina, or the like, which are used as abrasive grains constituting the cutting edge of the cutting blade 121 described above, or as abrasive grains constituting the grinding wheel that grinds the workpiece 200. Note that in the present invention, the coarse particles 61, 62 are not limited to abrasive grains.

In the present invention, the main coarse particles 61 having a particle size of F80 to F100 refer to coarse particles having a particle size of F80, F90, or F100 as specified in JIS R6000-1. In the present invention, the secondary coarse particles 62 having a particle size of F150 to F220 refer to coarse particles having a particle size of F150, F180, or F220 as specified in JIS R6000-1.

The ratio of the main coarse particles 61 to the sub-coarse particles 62 of the aggregate 6 is 1:3 to 1:10. The ratio of the main coarse particles 61 to the sub-coarse particles 62 of the aggregate 6 is the ratio (also called the ratio) between the number of the main coarse particles 61 constituting the porous plate 2 and the number of the sub-coarse particles 62. The ratio of the main coarse particles 61 to the sub-coarse particles 62 of 1:3 to 1:10 indicates that the ratio between the number of the main coarse particles 61 and the number of the sub-coarse particles 62 is 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc., and indicates that when the number of the main coarse particles 61 is N, the number of the sub-coarse particles 62 is 3×N or more and 10×N or less.

In the first embodiment, the porous plate 2 is formed such that the bonds 7 are connected to the outer surfaces of adjacent main coarse particles 61, to the outer surfaces of adjacent main coarse particles 61 and to the outer surfaces of adjacent sub-coarse particles 62, and to the outer surfaces of adjacent sub-coarse particles 62, with the main coarse particles 61 and the sub-coarse particles 62 being randomly dispersed. In the present invention, it is sufficient that the bonds 7 are connected to at least a portion of the outer surface of the main coarse particles 61 and at least a portion of the outer surface of the sub-coarse particles 62.

In the porous plate 2, pores 8 are formed between adjacent main coarse grains 61 or in the bonds 7 connected to adjacent main coarse grains 61, between adjacent main coarse grains 61 and sub-coarse grains 62 or in the bonds 7 connected to adjacent main coarse grains 61 and sub-coarse grains 62, between adjacent sub-coarse grains 62 or in the bonds 7 connected to adjacent sub-coarse grains 62. Note that the pores 8 (hereinafter referred to as main pores 81) between adjacent main coarse grains 61 or in the bonds 7 connected to adjacent main coarse grains 61, between adjacent main coarse grains 61 and sub-coarse grains 62 or in the bonds 7 connected to adjacent main coarse grains 61 and sub-coarse grains 62 are pores formed by the main abrasive grains. Pores 8 (hereinafter referred to as sub-pores 82) between adjacent sub-coarse grains 62 or within the bond 7 that connects adjacent sub-coarse grains 62 are pores formed by the sub-abrasive grains.

The main pores 81 have a larger cross-sectional shape in a direction parallel to the holding surface 21 of the porous plate 2 than the secondary pores 82. With this configuration, the porous plate 2 absorbs liquid (such as cutting water or cutting water containing cutting chips) that adheres to the holding surface 21 due to capillary action caused by the secondary pores 82 formed by the secondary abrasive grains, and ensures breathability through the main pores 81 formed by the primary abrasive grains.

The particle size of the main coarse particles 61 is F80 to F100 because if the particle size specified in JIS R6000-1 is larger than F80, the particle size will be too large to maintain the shape of the porous plate 2, and the large main pores connected to the main coarse particles exposed on the holding surface 21 will be transferred in a concave shape to the workpiece 200 being sucked and fixed, and if the particle size specified in JIS R6000-1 is smaller than F100, the main pores 81 will not be large enough to promote the breathability of the porous plate 2 (i.e., the main pores 81 will cause capillary action, and the porous plate 2 will not be able to ensure sufficient breathability to suck the workpiece 200).

The secondary coarse particles 62 have a particle size of F150 to F220 because this is suitable for filling the gaps between the main coarse particles 61 and forming pores 81, 82 that are not too small and can ensure breathability while still exerting capillary action. The secondary coarse particles 62 have a particle size of F150 to F220 because if the particle size specified in JIS R6000-1 is smaller than F220, the pores 81, 82 will be too small and the breathability of the porous plate 2 will be extremely poor, and if the particle size specified in JIS R6000-1 is larger than F150, the breathability of the porous plate 2 will be too high.

The processing device 100 having the above-mentioned configuration performs a processing operation as shown below. The processing device 100 uses the transport unit to take out one workpiece 200 from the cassette 150 and place it on the holding surface 21 of the porous chuck table 1. The processing device 100 suction-holds the back surface 205 of the workpiece 200 to the holding surface 21 of the porous chuck table 1 via the adhesive tape 209, and clamps the annular frame 210 with the clamp unit 4. The processing device 100 moves the porous chuck table 1 and the cutting unit 120 with the processing feed unit 141 and the index feed unit 142, captures an image of the workpiece 200 on the porous chuck table 1 with the imaging unit 130, and performs alignment to align the workpiece 200 with the cutting blade 121.

As shown in FIG. 5, the processing device 100 supplies cutting water from the cutting water nozzle 124, and while moving the porous chuck table 1 and the cutting blade 121 relatively along the division lines 203, cuts the cutting blade 121 into the division lines 203 of the workpiece 200 until it reaches the adhesive tape 209, cutting each division line 203 and cutting the workpiece 200 along the division lines 203. When the processing device 100 cuts the workpiece 200 along all the division lines 203 and divides the workpiece 200 into individual devices 204, it cleans the workpiece 200 with the cleaning unit 152 and stores it in the cassette 150, completing the processing operation.

Next, a method for manufacturing the porous chuck table according to the first embodiment will be described with reference to the drawings. FIG. 6 is a flow chart showing the flow of the method for manufacturing the porous chuck table shown in FIG. 2. FIG. 7 is a cross-sectional view showing a schematic diagram of a molding step in the method for manufacturing the porous chuck table shown in FIG. 6. FIG. 8 is a diagram showing an outline of a firing step in the method for manufacturing the porous chuck table shown in FIG. 6. FIG. 9 is a cross-sectional view showing an outline of a fixing step in the method for manufacturing the porous chuck table shown in FIG. 6.

The method for manufacturing the porous chuck table according to the first embodiment is a method for manufacturing the porous chuck table 1 described above, and as shown in FIG. 6, is composed of at least a mixing step 1001, a molding step 1002, a firing step 1003, and a fixing step 1004.

Mixing Step
In the mixing step 1001, the main coarse particles 61 and the sub coarse particles 62 which are the raw materials of the aggregate 6 are mixed with the raw material members of the bond which are the material of the bond 7 to prepare a mixture. The mixing ratio of the main coarse particles 61 and the sub coarse particles 62 to the raw material members of the bond is set according to the porous plate 2 to be manufactured.

(Molding step)
The molding step 1002 is a step of molding the mixture into a plate-like object 10 (shown in FIG. 77) having a shape corresponding to the porous plate 2. In the first embodiment, in the molding step 1002, as shown in FIG. 7, a pressure molding device 11 introduces the mixture into a cavity 13 of a mold 12 for molding the porous plate 2, and presses the mixture with a plate-like pressing member 14 to perform compression molding to mold the plate-like object 10. Then, after molding, the plate-like object 10 is removed from the mold 12.

(Firing step)
The firing step 1003 is a step of firing the molded plate-like object 10 to produce a porous plate 2. In the first embodiment, in the firing step 1003, as shown in FIG. 8, the plate-like object 10 is accommodated in a container 15, the container 15 is sealed with a lid 16, and the plate-like object 10 is accommodated in a firing furnace 17 together with the container 15, and the plate-like object 10 is fired by heating at a high temperature for a predetermined time at a predetermined temperature to produce a porous plate 2. The plate-like object 10 may be fired without being accommodated in the container 15, and if it is not accommodated in the container 15, it may be fired by placing a plate serving as a weight for firing on it, or by sandwiching it between plates.

(fixation step)
The fixing step 1004 is a step of fixing the porous plate 2 to the base 3. In the first embodiment, in the fixing step 1004, as shown in Fig. 9, the porous plate 2 is accommodated in the recess 33 of the base 3, and the porous plate 2 is fixed to the high surface portion 342 of the recess 33 of the base 3 with an adhesive (not shown) to manufacture the porous chuck table 1. After the fixing step 1004, the holding surface 21 of the porous chuck table 1 is ground and formed flat along the horizontal direction, and then the porous chuck table 1 is installed in the processing device 100 and used for processing the workpiece 200.

As described above, the porous chuck table 1 according to the first embodiment has a porous plate 2 in which the main coarse particles 61 and the sub-coarse particles 62 are fixed with the bond 7, forming large and small pores 81 and 82 in the porous plate 2, and the small sub-pores 82 generate capillary action, while the large pores 81 ensure breathability, and the liquid adhering to the holding surface 21 can be quickly sucked in and then sucked out by the even larger main pores 81. As a result, the porous chuck table 1 has the effect of quickly removing liquid adhering to the holding surface 21 side (back surface 205 or adhesive tape 209) of the workpiece 200 while ensuring breathability for holding the workpiece 200 of the porous plate 2, and suppressing the liquid from remaining on the holding surface 21.

Next, the inventors of the present invention confirmed the effects of the porous chuck table 1 described in embodiment 1. The results are shown in Table 1 below.

The results are shown in Table 1. In the confirmation, multiple porous plates 2 were manufactured with different ratios of primary coarse particles 61 with particle sizes of F80 to F100 as specified in JIS R6000-1 and secondary coarse particles 62 with particle sizes of F150 to F220, and the porous chuck table 1 equipped with each porous plate 2 was placed in the processing device 100 to confirm its breathability and the degree to which liquid adhering to the holding surface 21 was absorbed.

In the porous plate of Comparative Example 1 in Table 1, the ratio of main coarse particles 61 to secondary coarse particles 62 is 1:2, and in the porous plate of Comparative Example 2, the ratio of main coarse particles 61 to secondary coarse particles 62 is 1:13. In the porous plate 2 of the present invention 1, the ratio of main coarse particles 61 to secondary coarse particles 62 is 1:3, in the porous plate 2 of the present invention 2, the ratio of main coarse particles 61 to secondary coarse particles 62 is 1:5, and in the porous plate 2 of the present invention 3, the ratio of main coarse particles 61 to secondary coarse particles 62 is 1:10.

Comparative Example 1 had no problems with breathability, but it took a long time for the liquid adhering to the holding surface 21 to be absorbed, and there was a problem with how well the liquid was absorbed. It is believed that in Comparative Example 1, the occurrence of capillary action was insufficient. Comparative Example 2 had no problems with how well the liquid was absorbed, but there was a problem with breathability, and processing debris contained in the liquid clogged the porous plate 2.

In contrast to Comparative Example 1 and Comparative Example 2, Invention Products 1, 2, and 3 had no problems with breathability or liquid absorption.

Therefore, according to Table 1, by configuring the porous plate 2 with a ratio of 1:3 to 1:10 between the main coarse particles 61 with a particle size of F80 to F100 as specified in JIS R6000-1 and the secondary coarse particles 62 with a particle size of F150 to F220, the porous chuck table 1 can quickly remove liquid adhering to the holding surface 21 side (back surface 205 or adhesive tape 209) of the workpiece 200 while ensuring the breathability required for the porous plate 2 to hold the workpiece 200, and can prevent the liquid from remaining on the holding surface 21.

The present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the gist of the present invention. In the present invention, the processing device 100 is not limited to a cutting device that cuts the workpiece 200, but may be a laser processing device that irradiates the workpiece 200 with a laser beam to laser-process the workpiece 200, a grinding device that grinds the workpiece 200, a polishing device that polishes the workpiece 200, a byte cutting device that cuts the workpiece 200 with a byte, an expansion device 300 that expands the expand tape 211 attached to the workpiece 200 shown in FIG. 10 and divides it into individual devices 204 starting from a breakage starting point such as a modified layer formed on the workpiece 200, or a cleaning device 400 that removes a water-soluble protective film 212 formed on the surface 202 of the workpiece 200 after laser processing, etc., as shown in FIG. 11.

FIG. 10 is a cross-sectional view showing a schematic configuration example of an expansion device including a porous chuck table according to embodiment 1. FIG. 11 is a cross-sectional view showing a schematic configuration example of a cleaning device including a porous chuck table according to embodiment 1. In FIG. 10 and FIG. 11, the same parts as those in embodiment 1 are denoted by the same reference numerals, and the description thereof will be omitted.

The expansion device 300 shown in FIG. 10 is a processing device that holds the annular frame 210 attached to the outer edge of the expanding tape 211 laminated with the die attachment film with a frame holding part 301, and expands the expanding tape 211 and the die attachment film in contact with the holding surface 21 of the porous chuck table 1 while cooling them by moving the frame holding part 301 relative to the porous chuck table 1 cooled to -10 degrees or less, thereby breaking the die attachment film and dividing the workpiece 200 into individual devices 204 starting from the breaking starting point. Before performing the expansion work, the expansion device 300 suction-holds the workpiece 200 to the porous chuck table 1 and brings the expanding tape 211 into close contact with the holding surface 21. The porous chuck table 1 of the expansion device 300 is cooled to a temperature below freezing, so if moisture adheres to the expand tape 211, the moisture absorbed into the porous plate 2 freezes and expands inside the porous plate 2, causing damage to the porous plate 2. However, the porous chuck table 1 of the present invention quickly expels moisture from the porous plate 2.

The cleaning device 400 shown in FIG. 11 is a processing device that removes the protective film 212 and cleans the surface 202 of the workpiece 200 by rotating the porous chuck table 1 around its axis while supplying cleaning water 402 from a cleaning nozzle 401 to the surface 202 side of the workpiece 200 held by suction on the holding surface 21 of the porous chuck table 1.

REFERENCE SIGNS LIST 1 Porous chuck table 2 Porous plate 3 Base 5 Suction source 6 Aggregate 7 Bond 8 Pore 21 Holding surface 33 Recess 35 Suction path 61 Main coarse grain 62 Secondary coarse grain 81 Main pore (pore)
82 Subpore (pore)

Claims (1)

A porous chuck table including a porous plate constituting a holding surface, and a base having a suction passage communicating with a suction source and adapted to apply a negative pressure to the porous plate fitted in a recess,
The concrete structure has an aggregate, a bond for fixing the aggregate, and pores formed in gaps between the aggregate and the bond,
The aggregate is
It is composed of main coarse particles with particle sizes of F80 to F100 and secondary coarse particles with particle sizes of F150 to F220 as specified in JIS R6000-1.
The ratio of the main coarse particles to the sub coarse particles is 1:3 to 1:10;
The pores formed in the secondary coarse particles absorb the liquid adhering to the holding surface by capillary action,
A porous chuck table that ensures breathability by the pores formed by the main coarse grains.

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