JP2000021828A - Flattening work device for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flattening work device of wafers, which can prevent damages of the wafer in a protective film peeling process. SOLUTION: A brush cleaning device 74 for cleaning the protective film of a wafer 26 is installed in a plane grinding device. The brush cleaning device 74 forcedly peels and removes sludge adhered to the protective film, and the protective film is cleaned. Since peeling tape is adhered to the protective film, from which sludge is removed in a protective peeling process, damages to the wafer owing to the adhesion of sludge can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar processing apparatus for a wafer, and more particularly to a planar processing apparatus for a wafer for grinding a back surface of a semiconductor wafer in a semiconductor wafer manufacturing process.

[0002]

2. Description of the Related Art A surface grinding apparatus for grinding the back surface (one surface) of a semiconductor wafer includes a chuck table, a grindstone, a back surface cleaning device, and the like, and the chuck table absorbs the front surface (the other surface) of the semiconductor wafer. Hold, and
The grindstone is pressed against the back surface of the semiconductor wafer and the chuck table and the grinding wheel are rotated to grind the back surface of the wafer. Then, the ground wafer is removed from the chuck table, and the back surface of the ground wafer is cleaned by the back surface cleaning device.

A spin cleaning device can be exemplified as the back surface cleaning device. According to such a spin cleaning device, the chuck table of the spin cleaning device adsorbs the surface of the wafer, and while rotating the chuck table, injects cleaning water to the back surface of the wafer, thereby causing sludge adhering to the back surface of the wafer. Remove the deposits such as. By the way, since a chip has already been formed in the previous step on the surface of the wafer, a protective film is attached to protect the chip. After the wafer is ground / cleaned by a surface grinding device in a state where the protective film is attached,
The process proceeds to the next step of removing the protective film. In the protective film peeling step, for example, a method is used in which a tape is attached to the protective film and the protective film is peeled off from the wafer together with the tape.

[0004]

By the way, recent semiconductor wafers are required to be reduced in thickness in accordance with high integration of ICs. Therefore, the wafers are thinly ground by a surface grinding apparatus. However, when the wafer is ground to a small thickness, the strength of the wafer is reduced, so that the wafer may be damaged when the protective film is peeled off in the protective film peeling step.

[0005] The present invention has been made in view of such circumstances, and has as its object to provide a wafer plane processing apparatus capable of preventing wafer damage in a protective film peeling step.

[0006]

According to the present invention, in order to achieve the above object, a table for holding a wafer, a grindstone or polishing cloth for processing a wafer, and a relative movement between the grindstone or polishing cloth and the table are provided. Driving means for moving one side of the wafer by moving the whetstone or polishing cloth and the wafer relative to each other by moving the whetstone or the polishing cloth and the wafer, and A first cleaning means for cleaning one surface of the processed wafer, wherein a second cleaning means for cleaning the other surface of the wafer having the one surface processed is provided. And

In the present invention, first, the cause of wafer damage in the protective film peeling step was confirmed by an experiment, and it was found that the cause was sludge adhering to the protective film. That is, if sludge is adhered to the protective film, it is difficult for the tape to adhere to the adhered portion. When the tape is peeled off in such an imperfect bonding state, the peeling force is not evenly transmitted to the protective film, and the force may concentrate on a part of the protective film, and the concentrated force may damage the wafer. found. In particular, it has been found that sludge attached to the outer peripheral portion of the protective film has a great effect on wafer damage.

[0008] In view of the above, according to the first aspect of the present invention, a second cleaning means is provided to prevent the wafer from being damaged, and the second cleaning means cleans the other surface (front surface) of the wafer, that is, the protective film. The sludge was removed from the protective film. Accordingly, the present invention can prevent wafer damage in the protective film peeling step. According to the second aspect of the present invention, the brush cleaning means is employed as the second cleaning means, and the sludge adhered to the protective film is forcibly peeled off by the brush cleaning means, so that the sludge is reliably removed. be able to.

According to the third aspect of the present invention, after the wafer having undergone the planar processing is suction-held by the suction pad having substantially the same diameter as the wafer, the suction pad is transferred to the second by the transfer means.
The wafer was transported to the cleaning means, where the wafer was cleaned. In this manner, when the wafer is sucked and held by the suction pad having substantially the same diameter as the wafer, the entire surface of the wafer is sucked and held, so that the wafer can be transported without being damaged, and the entire surface of the wafer is transferred to the second cleaning means. Can be washed by pressing evenly. On the contrary,
When a part of the wafer is sucked and held, the weight of the wafer is concentrated on the sucked and held part, so that an extremely thin wafer may be broken during the transfer. Further, when the wafer is pressed against the cleaning means in the suction holding state, the probability of breakage of the wafer increases. Therefore, as described in the present invention, sucking and holding a wafer with a suction pad having substantially the same diameter as the wafer has a great effect in preventing damage to the wafer.

According to the fourth aspect of the present invention, the supporting portion for supporting the transfer means on the main body of the plane processing apparatus has rigidity to overcome a reaction force when the wafer is pressed against the brush of the second cleaning means. Therefore, the whole surface of the wafer can be evenly applied to the brush in combination with the fact that the entire surface of the wafer is sucked. Therefore, the entire other surface of the wafer can be uniformly cleaned. On the other hand, if the buffering member is provided on the support portion of the transfer means, the pressing force is buffered by the buffering member, so that a sufficient pressing force cannot be applied to the wafer, and the other surface of the wafer is entirely exposed. Cannot be uniformly washed. Therefore, providing the rigidity to the supporting portion as in the present invention has a great effect in cleaning the wafer.

According to the fifth aspect of the present invention, the brush of the brush cleaning means is formed in a roller shape longer than the diameter of the wafer, and is driven to rotate about the axis of the roller and the axis orthogonal to the axis. Therefore, the entire other surface of the wafer can be cleaned without rotating the wafer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a wafer plane processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a semiconductor wafer surface grinding apparatus to which the present invention is applied, and FIG. 2 is a plan view. As shown in FIG. 1, a main body 12 of the surface grinding apparatus 10 includes a cassette housing stage 14, an alignment stage 16, a rough grinding stage 18, a finish grinding stage 20,
And a cleaning stage 22.

Two cassettes 24, 24 are removably set on the cassette storage stage 14, and these cassettes 24, 24 store a large number of wafers 26 before back grinding. The wafers 26 are held one by one by a transfer robot 28 and sequentially transferred to the alignment stage 16 which is the next step. The transfer robot 28 is suspended and supported by a beam 30 erected on the main body 12 via an elevating device 32. The elevating device 32 is connected to a feed screw device (not shown) built in the beam 30. When the elevating device 32 is moved by the feed screw device, the transport robot 28 It can reciprocate in the directions indicated by the arrows A and B in FIGS. 1 and 2 along the arrangement direction. By the movement of the transfer robot 28 and the operation of the transfer robot 28, the wafers 26 are sequentially transferred in the surface grinding apparatus 10 according to a preset route.

When the transfer robot 28 is suspended and supported as in the present embodiment, the distance between the cassette housing stage 14 and the alignment stage 16 can be reduced, so that the size of the surface grinding apparatus 10 can be reduced. That is, when the transfer robot 28 is installed on the upper surface of the apparatus main body 12, the transfer robot 28 must be installed in the space between the cassette storage stage 14 and the alignment stage 16 because of the transfer of the wafer 26. For this reason, the surface grinding device 10 is unnecessarily increased in size by the space. On the other hand, in the surface grinding apparatus 10 of the present embodiment, the space above the apparatus main body 12 is effectively used as an installation space and an operation space for the transfer robot 28, so that the apparatus can be downsized.

The robot 28 is a general-purpose industrial robot having a horseshoe-shaped arm 34 for sucking and holding the wafer 26, and three links 36, 38, 40 and the like. At the tip of the arm 34, suction pads 35, 35 for sucking the wafer 26 are provided. The base end of the arm 34 is rotatably supported by a link 36 about an axis, and can be rotated about the axis by a driving force from a motor (not shown). Link 3
6 is rotatably connected to the link 38 via a shaft 42, and can rotate around the shaft 42 by a driving force from a motor (not shown). The link 38 is rotatably connected to the link 40 via a shaft 44, and can rotate around the shaft 44 by a driving force from a motor (not shown). Further, since the link 40 is connected to an output shaft of a motor (not shown) via the shaft 46, the link 40 can be rotated around the shaft 46 by driving the motor. The motor is connected to a lifting rod (not shown) of the lifting device 32. Therefore, according to the robot 28, the operation of the arm 34 and the three links 36, 38, and 40 is controlled by the respective motors, and the retracting operation of the lifting rod of the lifting device 32 is controlled. Can be taken out and transferred to the alignment stage 16.

The alignment stage 16 is a stage for aligning the wafer 26 transferred from the cassette 24 to a predetermined position. The wafer 26 aligned by the alignment stage 16 is sucked and held by the suction pads 35 of the transfer robot 28 again, and then transferred toward an empty chuck table 48. It is sucked and held at the position.

The chuck table 48 is installed on a turntable 50, and chuck tables 52 and 54 having the same function are installed on the turntable 50 at predetermined intervals. The chuck table 52 includes:
The wafer 26 that has been positioned on the rough grinding stage 18 and has been attracted is roughly ground here. The chuck table 54 is located on the finish grinding stage 20, and the attracted wafer 26 is subjected to finish grinding (fine grinding, spark out). Although not shown in FIGS. 1 and 2, the chuck tables 48, 52, and 54 each have a lower surface connected to a spindle of a rotation motor, and are rotated by the driving force of these motors.

The thickness of the wafer 26 sucked and held on the chuck table 48 is measured by a measuring gauge (not shown). The wafer 26 whose thickness has been measured is
1 and 2, the turntable 52 is positioned on the coarse grinding stage 18 by turning in the direction of the arrow C in FIG. 1 and FIG. 2, and the back surface of the wafer 26 is roughly ground by the cup-type grindstone 56 of the coarse grinding stage 18. The cup-shaped grindstone 56 is connected to an output shaft (not shown) of a motor 58 as shown in FIG.
8 the grinding wheel feeder 6 via the supporting casing 60
2 attached. The grindstone feeding device 62 moves the cup-shaped grindstone 56 up and down together with the motor 58, and the cup-shaped grindstone 56 moves the wafer 2
6 is pressed against the back surface. Thereby, the wafer 26
Back grinding is performed. The amount of downward movement of the cup-type grindstone 56, that is, the amount of grinding by the cup-type grindstone 56, is based on the reference position of the cup-type grindstone 56 registered in advance and the wafer 26.
Is set based on the thickness.

The thickness of the wafer 26 whose back surface has been roughly ground by the rough grinding stage 18 is measured by a thickness measuring gauge (not shown) after the cup-shaped grindstone 58 is retreated from the wafer 26. Wafer 26 with measured thickness
Are positioned on the finish grinding stage 20 by the rotation of the turntable 50 in the same direction, and are finely ground and sparked out by the cup-type grindstone 64 of the finish grinding stage 20 shown in FIG. The structure of the finish grinding stage 20 is the same as the structure of the rough grinding stage 18, and a description thereof will be omitted.

The wafer 26 finish-ground by the finish grinding stage 20 is separated from the wafer 26 by a cup-shaped grindstone 86.
Is moved to the position of the empty chuck table 48 shown in FIG. 1 by turning the turntable 50 in the same direction. The wafer is sucked by a suction pad 68 provided at the tip of a transfer arm (corresponding to transfer means) 66 and having substantially the same diameter as the wafer.
The wafer is conveyed to the cleaning stage 22 by rotation in the direction of the arrow D, and is cleaned there. The cleaning stage 22 will be described later.

The wafer 2 cleaned in the cleaning stage 22
6 is suction-held by the transfer robot 28, transferred to the cassette storage stage 14, and stored in a predetermined shelf of a predetermined cassette 24. The above is the flow of the wafer processing step by the surface grinding apparatus 10 of the present embodiment. Next, the cleaning stage 22 will be described.

As shown in FIGS. 1 and 2, the washing stage 22 includes a sink 70 having a spin cleaning device 72 as a first cleaning device and a spin cleaning device 72.
A brush cleaning device 74, which is a second cleaning device, is provided between the turntable 50 and the turntable 50. As shown in FIG. 3, the spin cleaning device 72 has a suction pad 76 having substantially the same diameter as the wafer 26, and a lower surface of the suction pad 76 is connected to a spindle 80 of a motor 78. Above the suction pad 76, a nozzle 82 for injecting cleaning water is provided. Therefore, according to the spin cleaning device 72, while rotating the wafer 26 sucked by the suction pad 76 with the motor 78, the nozzle 8
Cleaning water is sprayed from 2 toward the back surface 26 </ b> A of the wafer 26. As a result, deposits such as sludge attached to the back surface 26A of the wafer 26 are removed.

The brush cleaning device 74 has a disk-shaped plate 86 on which a brush 84 is implanted, and a spindle 90 of a motor 88 is connected to a lower surface of the plate 86. Therefore, according to the brush cleaning device 74,
The brush 84 is rotated by a motor 88, and the brush 84 is rotated.
Then, the surface 26B of the wafer 26 sucked by the suction pad 68 of the transfer arm 66 is pressed. This allows
Deposits such as sludge adhering to the protective film of the wafer 26 are removed.

In pressing the wafer 26 against the brush 84, the brush cleaning device 74 may be moved upward and pressed, or the transfer arm 66 may be moved downward and pressed. At this time, in order to evenly press the entire surface of the wafer 26 against the brush 84, the support portion 67 (see FIG. 1) of the transfer arm 66 needs to have a predetermined rigidity. The rigidity is a rigidity that overcomes the reaction force when the wafer 26 is pressed against the brush 84. Thus, in the present embodiment, the entire surface 26B of the wafer 26 can be evenly applied to the brush 84, in combination with the fact that the entire surface of the wafer 26 is sucked by the suction pad 68. Therefore, the entire surface 26B of the wafer 26 can be uniformly cleaned.

In order to clean the entire surface of the protective film of the wafer 26, the suction pad 68 may be rotated.
Further, the brush cleaning device 74 or the suction pad 68 may be swung in the horizontal direction. Further, the chips formed on the wafer 26 are protected by a protective film, but are not high in durability against physical impact. Therefore, if the pressing force of the brush 84 against the protective film is set to be high,
The brush 84 may damage the chip.
Is preferably set as low as possible, and
The material of the brush 84 is preferably as soft and strong as possible.

Next, the operation of the cleaning stage 22 configured as described above will be described. First, as shown in FIG. 3, the wafer 26 that has been finish-ground is held on the chuck table 54 with the back surface 26A facing upward. That is, the protective film attached to the surface 26 </ b> B of the wafer 26 is adsorbed on the suction pad 55. The back surface 26A of the wafer 26 is attached to the suction pad 6 of the transfer arm 66.
Adsorb at 8. Then, after the suction on the chuck table 54 side is released, the transfer arm 66 is rotated to transfer the wafer 26 to the cleaning stage 22. At this time, since the entire surface of the wafer 26 is sucked and held by the suction pad 68, the wafer 26 is not damaged during the transfer.
Further, the wafer 26 is not damaged during cleaning.

The wafer 2 transferred to the cleaning stage 22
6 is, first, in a state of being suction-held by the suction pad 68,
The protective film attached to the surface 26B is pressed against the brush 84 of the brush cleaning device 74 with a predetermined pressing force. Then, the brush 84 is rotated and the brush 8 is rotated.
4 and the wafer 26 are relatively horizontally swung. As a result, the brush 84 comes into contact with the entire surface of the protective film, so that it is possible to forcibly peel off and remove attached matter such as sludge adhered to the protective film.

When the cleaning of the protective film is completed, the wafer 26
Is transferred to the spin cleaning device 72 by the rotation operation of the transfer arm 66. Thereafter, the protection film of the wafer 26 is suction-held by the suction pad 76 of the spin cleaning device 72. Then, while rotating the wafer 26 with the motor 78, the cleaning water is supplied from the nozzle 82 to the back surface 26 of the wafer 26.
A is sprayed toward A to clean the back surface 26A. Then, after a predetermined time has elapsed, the spin cleaning device 72 is stopped. Thus, the cleaning of the wafer 26 by the cleaning stage 22 is completed.
In the cleaning stage 22, both surfaces of the wafer 26 are cleaned and then dried.

As described above, in the present embodiment, the brush cleaning device 74 for cleaning the protective film is provided in the surface grinding device 10,
Since the sludge adhering to the protective film is peeled and removed by the brush cleaning device 74, it is possible to prevent wafer damage in the protective film peeling step. In the present embodiment, a brush cleaning device 7 is used as a cleaning device for cleaning a protective film.
4, sludge adhering to the protective film is forcibly peeled off and removed, so that sludge can be reliably removed.

FIG. 4 is a side view showing a main part of a second embodiment of the cleaning apparatus for cleaning a protective film. The cleaning apparatus 100 shown in FIG. 3 employs a brush-type cleaning apparatus similarly to the cleaning apparatus shown in FIG. 3. In particular, this cleaning apparatus 100 has sludge adhering to the outer peripheral portion of the protective film 27. In consideration of the great effect on the damage, only the sludge adhering to the outer peripheral portion of the protective film 27 is used for the small brush cleaning device 10.
2 is configured to be peeled off.

In addition, the cleaning device 100 includes a protective film 27.
And a suction pad 104 for sucking the central portion of the suction pad 104. The suction pad 104 is configured to be rotated by a spindle 106. The brush cleaning device 102 is also provided with a spindle 108 to rotate the brush 103. Therefore, the cleaning device 10
According to 0, the brush 103 is rotated by the spindle 108 while rotating the wafer 26 by the spindle 106, and the brush 103 is pressed against the outer peripheral portion of the protective film 27, thereby removing sludge adhering to the outer peripheral portion of the protective film 27. It can be peeled off.

FIG. 5 is a sectional view of a principal part showing a third embodiment of the cleaning apparatus for cleaning a protective film. The cleaning device 110 shown in the figure is a cleaning device that removes sludge attached to the protective film 27 by using a roller-shaped brush 112 formed longer than the diameter of the wafer 26. The brush 1
12 have shafts 116 and 118 extending horizontally.
Are projected, and these shafts 116 and 118 are supported by a frame 114 formed in a concave shape. Therefore,
The brush 112 is rotatably supported by a frame 114. Further, since a spindle (not shown) of the motor 120 is connected to the shaft 116, the motor 1
Driving 20 causes brush 112 to rotate about axes 116 and 118.

Further, a spindle 122 disposed in a vertical direction is connected to the lower surface of the frame 114. Therefore, when the spindle 122 is rotated, the brush 112 rotates (turns) about the axis of the spindle 122. On the other hand, the back surface 26A of the wafer 26 is suction-held by suction pads 124 having substantially the same diameter as the wafer 26.

Therefore, according to the cleaning device 110 configured as described above, the brush 112 is rotated by the motor 120 and the brush 112 is turned by the spindle 122. And the brush 1 which makes a rotating motion and a turning motion
The protective film 27 is pressed against the substrate 22. Thus, the sludge attached to the entire surface of the protective film 27 can be removed by the brush 112 without rotating the wafer 26.

In this embodiment, the brush cleaning devices 74, 1 are used as the cleaning device (second cleaning means) for cleaning the protective film.
Although an example in which 00 and 110 are applied has been described, the present invention is not limited to this. For example, other cleaning devices such as a spray cleaning device that sprays high-pressure water onto the protective film to clean the protective film, and a cleaning device that cleans the protective film by rubbing a soft member such as a sponge on the protective film may be applied.

Further, in this embodiment, the surface grinding apparatus for grinding the back surface of the wafer has been described.
The present invention may be applied to a dicing apparatus that cuts a wafer into dice using a blade instead of an MP apparatus or a cup-type grindstone.

[0037]

As described above, according to the planar processing apparatus for a wafer according to the present invention, since the cleaning means for cleaning the protective film of the wafer is provided, the wafer can be prevented from being damaged in the protective film peeling step. . Further, the present invention employs, as a cleaning device for cleaning the protective film, a brush cleaning means for forcibly removing and removing the sludge attached to the protective film, so that the sludge can be surely removed.

Further, according to the present invention, an extremely thin wafer that has been planarized is suction-held by a suction pad having substantially the same diameter as the wafer, and the wafer is transferred to the second cleaning means. Can be prevented, and damage during cleaning can be prevented. Further, according to the present invention, the supporting portion for supporting the transfer means on the planar processing apparatus has rigidity to overcome the reaction force when the wafer is pressed against the brush of the second cleaning means, so that the wafer is entirely absorbed. Accordingly, the entire other surface of the wafer can be uniformly cleaned.

Further, according to the present invention, the brush of the brush cleaning means is formed in a roller shape longer than the diameter of the wafer, and the brush is driven to rotate about the axis of this roller and the axis orthogonal to the axis. The entire other surface of the wafer can be cleaned without rotating the wafer.

[Brief description of the drawings]

FIG. 1 is an overall perspective view of a surface grinding apparatus for a semiconductor wafer according to an embodiment of the present invention.

FIG. 2 is a plan view of the surface grinding apparatus shown in FIG. 1;

FIG. 3 is an explanatory view of a cleaning step including the first embodiment of the wafer protective film cleaning apparatus.

FIG. 4 is a side view showing a second embodiment of the wafer protective film cleaning apparatus.

FIG. 5 is a side view showing a third embodiment of the wafer protective film cleaning apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Surface grinding device 12 ... Main body 14 ... Cassette storage stage 16 ... Alignment stage 18 ... Rough grinding stage 20 ... Finish grinding stage 22 ... Cleaning stage 26 ... Wafer 72 ... Spin cleaning device 74, 100, 110 ... Brush cleaning device

Claims (5)

[Claims] 1. A table on which a wafer is held, a grindstone or a polishing cloth for processing the wafer, and the grindstone or the polishing cloth and the wafer are moved by moving the grindstone or the polishing cloth and the table relatively closer to each other. While pressing, a driving means for processing one surface of the wafer by relatively rotating the grindstone or polishing cloth and the wafer, and a first cleaning means for cleaning one surface of the wafer having the one surface processed. A planar processing apparatus for a wafer, comprising: a second cleaning means for cleaning the other surface of the wafer having the one surface processed. 2. The brush cleaning means according to claim 1, wherein said second cleaning means is a brush cleaning means which comes into contact with the other surface of said wafer and forcibly peels off and removes the adhered matter attached to said other surface. Wafer processing equipment. 3. The wafer processing apparatus according to claim 1, further comprising a transfer unit having a suction pad having substantially the same diameter as the wafer, wherein the suction pad of the transfer unit holds one surface of the wafer by suction. 3. The apparatus according to claim 1, wherein the other surface of the wafer is cleaned by the second cleaning unit. 4. A supporting portion for supporting said transfer means on a main body of said planar processing apparatus, said supporting portion supporting the other surface of said wafer by said second surface.
4. The apparatus according to claim 3, wherein the apparatus has a rigidity to overcome a reaction force when pressed against the cleaning means. 5. The brush of the brush cleaning means is formed in a roller shape longer than the diameter of the wafer, and the brush is driven to rotate about a roller axis and an axis perpendicular to the axis. 5. The apparatus for processing a flat surface of a wafer according to claim 2, 3 or 4.