JPH11354475A - Wafer polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for using a rotary reversing mechanism which cannot ensure sufficient sealing performance, by providing an unloader part receiving a polished wafer from a polishing head with a reversing mechanism for turning the wafer upside down. SOLUTION: An unloader part 11 having a wafer-reversing unit comprises a pair of claws 13, a twin cylinder 14, a rotary shaft 15, a bearing 16, a rotary actuator 17, a cylinder 18 moving up and down, and a cylinder 19 moving horizontally. A wafer 10 is pinched with the pair of claws 13 at the side of the peripheral portion thereof, the pair of claws 13 is fixed to the tip of the rotary shaft 15 via the twin cylinder 14, and the rotary shaft 15 is held by the bearing 16. The twin cylinder 14 opens and closes the claws 13 and the rotary actuator 17 is joined to the rear end of the rotary shaft 15 with the bearing 16 therebetween. The rotary actuator 17 rotates the rotary shaft 15 to turn the wafer 10 upside down.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for polishing a semiconductor wafer, and more particularly to a structure of an unloader provided at a portion for transferring a wafer, which has been polished in a polishing apparatus, to a cleaning apparatus.

[0002]

2. Description of the Related Art FIG. 3 shows the overall configuration of a conventional polishing apparatus used for polishing (polishing) a wafer. In FIG. 3, reference numeral 20 denotes a polishing unit, 25a and 25.
b is a cassette, 26 is a robot for transferring wafers, 27
Denotes a loader section, 40 denotes an unloader section (also a secondary polishing section), and 30 denotes a cleaning device section.

[0003] A polishing apparatus section 20 is provided on a base 29 of the apparatus main body. The polishing device section 20 includes a turntable 21, a polishing head 22, a dressing head 23, and the like. A loader unit 27 and an unloader unit 40 are provided in the turning range of the polishing head 22, and a transfer robot 26 is disposed at a position adjacent to the loader unit 27. In the drawing, reference numeral 28 denotes a cleaning device for cleaning the polishing head 22, which is used for cleaning the suction surface of the polishing head 22 before holding the wafer.

[0006] A cleaning unit 30 used for cleaning the polished wafer is provided adjacent to the base 29 of the apparatus main body. The cleaning unit 30 includes a wafer transfer robot 31, a double-sided brushing device 32, two spin cleaning devices 34 and 35, a reversing mechanism 38, and the like, as described later.

The polishing unit 20 is used for primary polishing, which is the main polishing. FIG. 6 shows a schematic configuration of the polishing apparatus section 20. The polishing device 20 includes a turntable 21, a polishing head 22, a dressing head 23, and a polishing liquid supply nozzle 5.
9 and the like. The turntable 21 has a polishing cloth 52 mounted on its upper surface, and is driven by a rotation drive mechanism 53 arranged below. The polishing head 22 includes a pressing and rotating mechanism 54, a main shaft 55 extending downward from the pressing and rotating mechanism 54, a wafer holding plate 56 connected to a lower end of the main shaft 55, and the like. Holding plate 56
A backing pad 57 is attached to the lower surface of the wafer, and the wafer 10 to be processed is held on the lower surface side of the wafer holding plate 56 via the backing pad 57. The dressing head 23 is used for adjusting the flatness of the polishing pad 52 and removing clogging.

The polishing of the wafer 10 is performed as follows. First, the polishing pad 52 is mounted on the turntable 21, and the wafer 10 is sucked to the lower surface of the wafer holding plate 56 via the backing pad 57. Next, the turntable 21 is rotated, and a polishing liquid (a solution in which fine abrasive grains are suspended) is supplied to the surface of the polishing cloth 52 from a polishing liquid supply nozzle 59. Finally, the pressurizing and rotating mechanism 54 is driven to press the wafer 10 against the surface of the polishing pad 52 while rotating, so that primary polishing, which is main polishing, is performed.

In FIG. 3, the wafer 10a is loaded on the base 29 in a state accommodated in the cassette 25a, and is unloaded from the base 29 in a state accommodated in the cassette 25b after the polishing process. Wafer 10a
Are housed in cassettes 25a and 25b with the polished surface (circuit forming side, referred to as surface A) facing upward, as shown in FIG.

As described above, by accommodating the wafer in the cassette with the polished surface (A side) of the wafer facing upward, the arm of the robot 26 (described later) sucks the wafer by the vacuum chuck mechanism provided at the tip thereof. When transporting the wafer, dent flaws and stains are prevented from being generated on the polished surface of the wafer.

The wafer transfer robot 26 takes out the wafer 10 from the cassette 25a, turns the wafer 10 upside down, and lowers it on the loader unit 27. Therefore, as shown in FIG. 3, the non-polished surface (B surface) of the wafer 10b placed on the loader unit 27 is the upper surface. Next, the polishing head 22 pivots above the loader unit 27, and the loader unit 2
The wafer 10b on the wafer 7 is held from the side B and transferred onto the turntable 21 of the polishing apparatus 20. Then
The primary polishing of the wafer 10c is performed.

When the primary polishing of the wafer 10c is completed,
The polishing head 22 rises while holding the wafer,
Then, it turns to unloader part (also secondary polishing part) 4
Move up to zero. Unloader section (also secondary polishing section)
At 40, the polishing head 22 is lowered while holding the wafer, and the polishing surface is subjected to secondary polishing using the secondary polishing platen 41. By this secondary polishing, the surface accuracy of the polished surface of the wafer is further enhanced.

FIG. 4 is a sectional view taken along the line YY of the unloader section (also a secondary polishing section) 40. In FIG. 4, 4
Reference numeral 1 denotes a surface plate for secondary polishing, which has a rotation drive mechanism at a lower portion. Reference numeral 42 denotes a receiving table, which is used to receive the wafer after the secondary polishing from the polishing head 22.
A guide 43 and a cylinder 44 for raising and lowering the receiving table 42 are provided below the receiving table 42.

When the secondary polishing of the wafer is completed, the wafer receiving table 42 is raised, the wafer is placed on the pins provided on the upper surface, and stopped above the secondary polishing platen 41. At this time, the non-polished surface B of the wafer is the upper surface. Here, a robot 31 provided in the cleaning unit 30 described below receives the wafer.

Next, the cleaning unit 30 shown in FIG. 3 will be described. The cleaning unit 30 is divided into four rooms. In FIG. 3, the first room from the left contains a double-sided brushing device 32 and a robot 31 for transferring a wafer. The second room accommodates a first spin cleaning device 34, the third room accommodates a reversing mechanism 38, and the fourth room accommodates a second spin cleaning device 35.

The wafer is taken out from an unloader section (also a secondary polishing section) 40 on a base 29 by a robot 31 and carried into a cleaning apparatus section 30. In the unloader section (also a secondary polishing section) 40, the wafer is placed on the receiving table 42 (FIG. 4) with the non-polished surface (surface B) facing upward. Is held from the side and the wafer is carried into the double-sided brushing device 32.

After the double-sided brushing is completed in the double-sided brushing apparatus 32, the wafer is transferred to the robot 31.
To the first spin cleaning device 34. In the first spin cleaning device 34, the B surface of the wafer is on the upper surface,
From the viewpoint of cleaning efficiency, the cleaning on the side B is mainly performed.

After the cleaning in the first spin cleaning apparatus 34, the wafer is moved to a reversing mechanism 38 as shown in FIG.
As a result, the robot is turned around the turning shaft 39 and the upper and lower surfaces are inverted. In the second spin cleaning device 35, the wafer A
The surface becomes the upper surface, and the cleaning is mainly completed by cleaning the surface A side. The cleaned wafer is carried out of the cleaning device 30 by the robot 26 and is stored in the cassette 25b on the base 29 with the surface A facing up.

(Problems of the Prior Art) As described above, in the conventional polishing apparatus, the revolving reversing mechanism for reversing the upper and lower surfaces of the wafer is provided between the first spin cleaning apparatus 34 and the spin cleaning apparatus 35. 38 are provided. Since the turning type reversing mechanism 38 is configured to turn with a large radius around the turning shaft 39, it takes a lot of time to turn, which is a factor that causes a decrease in the productivity of the polishing apparatus. .

Further, since each room in which the spin cleaning devices 34 and 35 are housed is filled with a mist of the cleaning liquid, each room is separated by a door. However, when the wafer is transferred, the door is opened and closed, and the mist of the cleaning liquid flows into the adjacent room. For this reason, there has been a problem in securing the sealing performance of the bearing portion of the turning shaft 39 of the turning type reversing mechanism 38.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems with respect to the transfer of a wafer in a wafer polishing apparatus. It is another object of the present invention to provide a wafer polishing apparatus which does not need to use a turning type reversing mechanism, which has a problem in securing, and which can shorten the time required in the unloader section and the cleaning apparatus section after polishing the wafer.

[0020]

SUMMARY OF THE INVENTION A wafer polishing apparatus according to the present invention includes a turntable on which a polishing cloth is mounted, a polishing head for holding a wafer, a polishing apparatus section for polishing a wafer, and polishing is completed. An unloader unit that receives the wafer from the polishing head, a robot that receives and transports the wafer from the unloader unit, a cleaning device that performs cleaning of the wafer transported by the robot,
Wherein the unloader section has a reversing mechanism for reversing the upper and lower surfaces of the wafer.

According to the wafer polishing apparatus of the present invention, after the upper and lower surfaces of the wafer are inverted in the unloader section where there is no problem of scattering of the cleaning liquid, the robot receives the wafer and transfers it to the cleaning apparatus section. Therefore, the problem of securing the sealing performance of the reversing mechanism, which has been a concern in the conventional apparatus, can be solved.

Further, since the subsequent cleaning step is performed in a state where the polished surface side (A side), which particularly requires cleaning, is on the upper surface, an efficient cleaning operation can be realized. Preferably, the reversing mechanism is held on or near the center plane of the thickness of the wafer (preferably within 5 times the thickness of the wafer) with the outer diameter portion of the wafer held between the sides. The upper and lower surfaces of the wafer are inverted around a rotation axis passing through the wafer. By configuring the reversing mechanism in this manner, the time required for reversing the wafer can be reduced, and the time required for the entire polishing process can be reduced.

[0023]

FIG. 1 shows a schematic configuration of a wafer polishing apparatus according to the present invention. The difference between the wafer polishing apparatus according to the present invention (FIG. 1) and the conventional wafer polishing apparatus (FIG. 3) lies in the configuration of the unloader section 11 and the transfer of the wafer from the first spin cleaning apparatus to the second spin cleaning apparatus. Robot 36. Other configurations, namely, the cassette 25
The components a and 25b, the robot 26, the loader unit 27, the polishing device unit 20, the robot 31, the double-sided brushing device 32, and the like are common to the conventional device (FIG. 3). Therefore, the same parts as those of the conventional device are denoted by the same reference numerals, and detailed description is omitted. That is, the configuration and functions of the unloader unit 11 (also serving as a wafer reversing unit) and the robot 36 in FIG. 1 will be mainly described below.

FIG. 2 is a cross-sectional view of the section XX of the unloader section 11 (also serving as a wafer reversing unit). In FIG. 2, reference numeral 12 denotes a surface plate for secondary polishing, which has a rotation drive mechanism at a lower portion. An unloader unit 11 also functions as a wafer reversing unit. The unloader unit 11 includes a pair of claws 13, a twin cylinder 14, a rotating shaft 15, and a bearing 1.
6, a rotary actuator 17, a vertical moving cylinder 18, a horizontal moving cylinder 19, and the like.

The wafer 10 is held by a pair of claws 13
The outer peripheral portion is held between the sides. A pair of claws 1
3 is attached to the tip of a rotating shaft 15 via a twin cylinder 14, and the rotating shaft 15 is supported by bearings 16. The twin cylinder 14 opens and closes the claw 13. A rotary actuator 17 is connected to the rear end of the rotating shaft 15 with the bearing 16 interposed therebetween. The rotary actuator 17 rotates the rotating shaft 15 to rotate the wafer 10
Upside down.

The bearing 16 is supported by the tip of a piston of a vertical movement cylinder 18,
Are supported by the tip of the piston of the horizontal movement cylinder 19. The vertical movement cylinder 18 is used for the wafer 10
The horizontal movement cylinder 19 moves the wafer 10 in the horizontal direction. The claw 13 is not always above the platen 12 for secondary polishing, but is retracted by the horizontally moving cylinder 19 in a state of retreating leftward in the drawing.

Next, the operation of the unloader unit (also serving as a wafer reversing unit) 11 will be described. When the polishing of the wafer in the polishing device section 20 is completed, the polishing head 22 rises while holding the wafer, and then turns and moves to above the unloader section 11 (also serving as a wafer reversing unit). Then, the secondary polishing of the wafer is performed using the secondary polishing platen 12. When the secondary polishing is completed,
The polishing head 22 rises and stops while holding the wafer.

Next, the claw 13 is moved to the horizontal movement cylinder 19.
Moves to the right in the figure, and stops below the polishing head 22. Next, the claw 13 is raised by the vertical movement cylinder 18 and stops immediately below the wafer held by the polishing head 22. Nitrogen gas is blown from the lower surface of the polishing head 22, and the claws 13 receive the wafer from the polishing head 22. Next, the claw 13 is driven by the twin cylinder 14 to hold the outer peripheral portion of the wafer 10 from the side. Thereafter, the claw 13 descends and stops. Next, the polishing head 22 turns and separates from above the secondary polishing platen 12.

Next, the claw 13 is moved to the vertical movement cylinder 18.
The wafer 10 is again raised by the
Move 2 to the dodge position. At this position, the upper and lower surfaces of the wafer 10 are inverted by rotating the rotary shaft 17 with the rotary actuator 16, and the polished surface (A surface) is turned to the upper surface side.

Next, the arm of the robot 31 of the cleaning unit 30 moves forward and stops below the wafer 10. Next, the arm of the robot 31 is raised, and the robot hand is stopped immediately below the wafer. Next, the claws 13 open,
The robot hand receives the wafer from the nail 13. After the arm of the robot 31 descends, it retreats into the cleaning device 30, whereby the wafer is carried into the cleaning device unit 30. Note that, on the robot hand, the polished surface (A surface) of the wafer is on the upper surface.

In the cleaning device section 30, first, the wafer is brushed by the double-sided brushing device 32. In this brushing, the polished surface (A surface) of the wafer is on the upper surface side, contrary to the case of the conventional apparatus. When the brushing is completed, the wafer is transferred to the first spin cleaning device 34 by the robot 31. Also in the first spin cleaning device 34, the polished surface (A surface) of the wafer is on the upper surface side, contrary to the case of the conventional device.

After the spin cleaning in the first spin cleaning device 34 is completed, the wafer is transferred to the second spin cleaning device 35 by the robot 36. The robot 36
This is an alternative to the pivoting reversing mechanism 38 in the conventional apparatus (FIG. 3), and the same surface (that is, the wafer is not reversed)
The transfer is performed from the first spin cleaning device 34 to the second spin cleaning device 35 with the (A surface) kept on the upper surface side.

As described above, according to this wafer cleaning device, the double-sided brushing device 32 and the first spin cleaning device 3
In the fourth and second spin cleaning devices 35, the posture in which the polished surface (A surface) of the wafer is on the upper surface side is maintained. Therefore, the wafer is cleaned with high cleaning efficiency.

[0034]

According to the wafer polishing apparatus of the present invention, it is not necessary to use a turning type reversing mechanism which has a problem in securing the sealing performance of the bearing portion in the cleaning device. At the same time, a series of cleaning operations can be performed particularly with the polished surface (side A) requiring cleaning on the upper surface side, so that an efficient cleaning operation can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a wafer polishing apparatus according to the present invention.

FIG. 2 is a sectional view taken along the line XX in FIG. 1;

FIG. 3 is a diagram showing an entire configuration of a conventional wafer polishing apparatus.

FIG. 4 is a sectional view taken along line YY in FIG. 3;

FIG. 5 is a view for explaining the operation of a turning type reversing mechanism used in a conventional wafer polishing apparatus.

FIG. 6 is a schematic configuration diagram of a polishing apparatus.

[Explanation of symbols]

Reference numeral 10: wafer, 11: unloader unit (also wafer reversing unit), 12: surface plate for secondary polishing, 13
... Claw, 14 ... Twin cylinder, 15 ... Rotating shaft, 16 ... Rotating bearing, 17 ... Rotary actuator, 18 ... Cylinder for vertical movement, 19 ... Cylinder for horizontal movement , 20 ... polishing unit, 21 ...
Turntable, 22: polishing head, 23: dressing head, 25a, 25b: cassette, 2
6 ... Robot, 27 ... Loader part, 28 ... Cleaning device (for polishing head), 29 ... Base, 30 ...
Cleaning device section, 31 Robot, 32 Double-sided brushing device, 34 First spin cleaning device, 35
... Second spin cleaning device, 36 ... Robot, 38
... Swivel reversing mechanism, 39 ... Swivel axis, 40 ...
Unloader part (also secondary polishing part), 41: secondary polishing surface plate, 42: receiving table, 43: guide part, 44: cylinder, 52: polishing cloth, 53 ...
.Rotation drive mechanism, 54 ... Pressure and rotation mechanism, 55
・ Spindle, 56 ... Wafer holding plate, 57 ...
Backing pad, 59 ... polishing liquid supply nozzle.

Claims (2)

[Claims] 1. A polishing apparatus comprising: a turntable on which a polishing cloth is mounted; a polishing head for holding a wafer; and a polishing apparatus for polishing the wafer; an unloader for receiving the polished wafer from the polishing head; A robot for receiving and transporting the wafer from the unit, and a cleaning unit for cleaning the wafer transported by the robot, wherein the unloader unit includes a reversing mechanism for reversing the upper and lower surfaces of the wafer. A wafer polishing apparatus, comprising: 2. The method according to claim 1, wherein the reversing mechanism holds the upper and lower surfaces of the wafer around a rotation axis passing on or near a center plane of the thickness of the wafer while holding the outer diameter portion of the wafer from the side. 2. The wafer polishing apparatus according to claim 1, wherein the apparatus is turned over.