JP3651820B2 - Method and apparatus for double-side polishing of workpiece - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a workpiece double-side polishing method and apparatus for automatically polishing both surfaces of a workpiece such as a semiconductor wafer, a glass substrate, and other ceramic substrates.
[0002]
[Prior art]
For example, a double-side polishing apparatus for polishing both surfaces of a semiconductor wafer is a polishing constituted by an upper polishing plate, a lower polishing plate, and a thin plate-like carrier for holding the semiconductor wafer between the upper and lower polishing plates. An apparatus main body, a loading unit for transferring a wafer stored in a wafer storage cassette disposed in the vicinity of the polishing apparatus main body to the polishing apparatus main body, and a polished wafer from the polishing apparatus main body to the wafer storage cassette And an unloading section.
[0003]
The loading unit and the unloading unit in such a double-side polishing apparatus are provided with an air vacuum type adsorption device as disclosed in, for example, JP-A-6-15565.
That is, the loading unit and the unloading unit are respectively provided with a loading arm and an unloading arm driven by a robot, and an adsorption device using an air vacuum system is provided on the free end side of the loading arm and the unloading arm. Yes.
[0004]
Then, the free end of the loading arm moves to the wafer storage cassette side arranged near the polishing apparatus main body, and the wafer is attracted to the thin plate carrier arranged on the lower polishing plate while adsorbing the upper surface of the wafer by the adsorption device. The wafer to be polished is stored in a wafer insertion hole provided in the carrier.
Further, the upper surface of the polished wafer is sucked by a suction device provided at the free end of the unloading arm and is transported to the wafer storage cassette.
[0005]
[Problems to be solved by the invention]
By the way, in the above-described conventional polishing processing apparatus, the double-side polished wafer is transported to the wafer storage cassette in a state in which the upper surface is adsorbed from the main body of the polishing apparatus by the suction device provided on the unloading arm. Therefore, there has been a technical problem of scratching the upper surface of the polished wafer by the adsorption action.
[0006]
Generally, in this type of polishing apparatus, when polishing both surfaces of a wafer by rotating both upper and lower polishing plates in opposite directions, a water-soluble abrasive is flowed, and a slurry containing the abrasive Such a residue enters the wafer suction portion of the unloading arm, and this residue is damaged, leaving a defect on the suctioned portion of the upper surface of the wafer, resulting in poor semiconductor productivity.
[0007]
Therefore, as disclosed in Japanese Patent Laid-Open No. 6-15565, a special watering device for cleaning the wafer adsorbing portion is provided. However, residues such as slurry are completely washed away. This is difficult, and the apparatus is inevitable.
[0008]
The present invention has been made to solve the technical problem of such a conventional one, and the surface of the polished wafer (work) is not damaged by the unloading portion. An object of the present invention is to provide a double-side polishing method and apparatus capable of keeping the defect rate low.
[0009]
[Means for Solving the Problems]
In the method for double-side polishing a workpiece according to the present invention, which is achieved to achieve the above object, the workpiece inserted into the carrier is sandwiched between the upper polishing plate and the lower polishing plate, and the upper and lower polishing plates are rotated to rotate the workpiece. A step of simultaneously polishing both the upper and lower surfaces, a step of separating the upper polishing plate and the lower polishing plate, and a step of moving the carrier to the upper polishing plate side to leave the workpiece placed on the lower polishing plate And a step of storing the workpiece left on the lower polishing plate in a workpiece storage cassette by an unloading arm in contact with the peripheral edge surface of the workpiece.
[0010]
The workpiece double-side polishing apparatus according to the present invention includes an upper polishing plate that is rotationally driven by a driving actuator, a lower polishing plate that is rotationally driven by a driving actuator, and the upper polishing plate and the lower polishing plate. A carrier disposed between the polishing plate moving mechanism for separating the upper polishing plate and the lower polishing plate, and a state in which the upper polishing plate and the lower polishing plate are separated by the polishing plate moving mechanism. And a carrier moving mechanism for moving the carrier to the upper polishing plate side, and an unloading unit for storing the workpiece left on the lower polishing plate in a workpiece storage cassette in contact with the peripheral edge surface of the workpiece And an arm.
[0011]
In this case, it is preferable that the unloading arm has a shape corresponding to the peripheral edge surface of the workpiece to be polished.
[0012]
Preferably, the carrier is held at its peripheral side by a tension plate, the tension plate is rotationally driven by a drive actuator, and the center position of the insertion hole into which the workpiece is inserted is defined by the upper polishing plate. And configured to be eccentric with respect to the rotational axis of the lower polishing plate.
In the present invention, specifically, a semiconductor wafer is employed as one aspect of the workpiece.
[0013]
According to the above-described method and apparatus according to the present invention, the workpiece left on the lower polishing plate after completion of double-side polishing is stored in the workpiece storage cassette by the unloading arm in contact with the peripheral edge surface of the workpiece. Thus, the technical problem of leaving scratches on both the upper and lower surfaces of the polished workpiece can be solved, the yield of the semiconductor wafer can be increased, and the productivity of the semiconductor can be improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a double-side polishing method and apparatus for a workpiece according to the present invention will be described based on an embodiment shown in a drawing using a semiconductor wafer as a workpiece.
1 is a cross-sectional view showing a state in which a semiconductor wafer is loaded onto a polishing apparatus, FIG. 2 is a cross-sectional view showing a state in which the semiconductor wafer is subjected to double-side polishing by the polishing apparatus, and FIG. 3 is a polishing apparatus. FIG. 2 is a cross-sectional view showing a state in which a polished semiconductor wafer is unloaded from the same, and the same portions are denoted by the same reference numerals.
[0015]
First, in FIG. 1, a disc-shaped upper polishing plate 1 is attached to a support shaft 2 at the center thereof, and the support shaft 2 is held by a bearing (not shown) so as to be rotatable. A polishing cloth 3 is attached to the lower surface of the upper polishing plate 1 in a flat shape.
The support shaft 2 is formed in a hollow shape so that the abrasive is introduced from the upper part of the center hole 2a, and an abrasive supply hole 1a is formed at an appropriate position of the upper polishing plate 1 and the polishing cloth 3. ing.
[0016]
A pulley 4 is attached to the support shaft 2, and a belt 7 is stretched between the pulley 4 and a pulley 6 attached to a rotating shaft of a motor 5 as a drive actuator.
Therefore, the upper polishing plate 1 is configured to be rotated by the support shaft 2 by driving the motor 5.
[0017]
The assembly including the upper polishing plate 1, the support shaft 2, the motor 5 and the like is configured so as to be integrally movable in the vertical direction in the drawing, and constitutes a polishing plate moving mechanism 8.
[0018]
A carrier holding plate 10 constituting a carrier moving mechanism 9 is attached to the support shaft 2 so as to move up and down along the support shaft 2. A flange 11 is fitted into the upper portion of the carrier holding plate 10, and a rod 12 is vertically attached to a part of the flange 11, and the carrier holding plate 10 is driven by a vertical driving action on the rod 12. Is configured to be moved up and down along the support shaft 2.
[0019]
The outer peripheral edge of the carrier holding disk 10 is bent downward to form a cylindrical portion 10a, and a plurality of engagement elements 13 are attached to the lower end of the cylindrical portion 10a along the circumferential direction. .
These engagement elements 13 are provided with, for example, electromagnetic plungers, and an operation of the engagement element 13 can hold an annular tension plate for stretching a carrier, which will be described later, on its outer peripheral surface. It is configured.
[0020]
On the other hand, the disc-shaped lower polishing plate 14 is attached to a support shaft 15 at the center thereof, and the support shaft 15 is held by a bearing (not shown) so as to be rotatable. A polishing cloth 16 is attached to the upper surface of the lower polishing plate 14 in a flat shape.
A pulley 17 is attached to the support shaft 15, and a belt 20 is stretched between the pulley 17 and a pulley 19 attached to a rotation shaft of a motor 18 as a drive actuator.
Therefore, the lower polishing plate 14 is configured to be rotated by the support shaft 15 by driving the motor 18.
[0021]
A carrier drive board 21 is attached to the support shaft 15 so as to be rotatable about the support shaft 15. A spur gear 22 is attached to a cylindrical body portion 21a surrounding the support shaft 15 of the carrier drive board 21, and a spur gear 22 is attached to a spur gear attached to a rotating shaft of a motor 23 as a drive actuator. The gears 24 are arranged so as to mesh with each other.
Therefore, by driving the motor 23, the carrier driving board 21 is rotationally driven.
[0022]
Further, the outer peripheral edge of the carrier driving board 21 is bent upward and formed into a cylindrical portion 21b. An annular tension for stretching the thin plate-like carrier 25 is formed on the inner peripheral portion of the upper end of the cylindrical portion 21b. The plate 26 is configured to be accommodated so that the tension plate 26 can be rotated together with the carrier drive board 21.
[0023]
As shown in FIG. 4, the thin plate carrier 25 and the tension plate 26 are made of a thin plate such as stainless steel, and are provided with circular insertion holes 25 a for inserting the semiconductor wafer 27. Yes.
Incidentally, the insertion hole 25a provided in the carrier 25 is formed in a state where the center position thereof is eccentric with respect to the rotational axes of the upper polishing plate 1 and the lower polishing plate 14.
[0024]
A loading unit and an unloading unit are disposed on both sides of the polishing apparatus main body having the above-described configuration.
First, the loading unit 28 constitutes a robot by a loading arm 29 and an actuator 30 that drives the loading arm 29 in the vertical direction and the circumferential direction.
The loading arm 29 sucks the semiconductor wafer stored in the work storage cassette 31 by suction means such as an air vacuum type, and the thin plate carrier 25 attached to the carrier driving board 21 as shown in FIG. The transported semiconductor wafer 27 can be inserted into the insertion hole 25a.
[0025]
Although the details of the unloading unit 32 will be described later, a robot is constituted by an unloading arm 33 for transporting the polished semiconductor wafer 27 to a work storage cassette and an actuator 34 for driving the unloaded arm 32 in the circumferential direction. ing.
[0026]
In the above configuration, in the state of FIG. 1 in which the upper polishing plate 1 is pulled upward by the polishing plate moving mechanism 8 and the upper polishing plate 1 and the lower polishing plate 14 are separated from each other, As described above, the semiconductor wafer 27 stored in the work storage cassette 31 is sucked.
Then, the semiconductor wafer 27 is transported to the insertion hole 25 a provided in the carrier 25 by driving the actuator 30.
[0027]
FIG. 2 shows a state in which the upper polishing plate 1 is lowered by the polishing plate moving mechanism 8 and both surfaces of the semiconductor wafer 27 are polished in a state where the semiconductor wafer 27 is inserted into the insertion hole 25 a provided in the carrier 25. Show.
In FIG. 2, the upper polishing plate 1 and the lower polishing plate 14 rotate in opposite directions, and the carrier 25 that holds the semiconductor wafer 27 is also rotated integrally with the rotational movement of the carrier driving board 21. .
By such rotational movement, both surfaces of the semiconductor wafer 27 are polished.
[0028]
After the polishing step, the carrier holding plate 10 is lowered by the carrier moving mechanism 9 in the state of FIG. 2, and the engagement element 13 formed of an electromagnetic plunger provided in the carrier holding plate 10 is operated to move the carrier 25. An annular tension plate 26 to be stretched is held on its outer peripheral surface.
[0029]
In this state, the upper polishing plate 1 is pulled up by operating the polishing plate moving mechanism 8 so that the upper polishing plate 1 and the lower polishing plate 14 are separated from each other as shown in FIG. It is pulled upward by the holding plate 10.
Therefore, the polished semiconductor wafer 27 is left in a state of being placed on the lower polishing plate 14.
[0030]
FIG. 3 shows a process of unloading the semiconductor wafer 27. At the time of unloading, the unloading unit 32 works and the polished semiconductor wafer 27 is transported by the unloading arm 33. FIG. 5 shows the situation when the state is viewed from above. As described above, the unloading arm 33 is driven by the actuator 34 so as to be rotated in the horizontal direction.
[0031]
The free end 33a of the unloading arm 33 has a shape corresponding to the peripheral edge surface of the polished semiconductor wafer 27 as shown in FIG.
Accordingly, in FIG. 5, the semiconductor wafer 27 left on the lower polishing plate 14 is pushed out by the unloading arm 33 in contact with the end surface of the wafer 27 by the counterclockwise rotation of the unloading arm 33. Then, it is stored in the work storage cassette 35 while sliding on the upper surface of the lower polishing plate 14.
[0032]
After the above steps, the polishing plate moving mechanism 8 and the carrier moving mechanism 9 are operated again to lower the upper polishing plate 1 and the carrier holding plate 10, and then the engagement plate 13 is disengaged by the engagement element 13. By raising the upper polishing plate 1 and the carrier holding plate 10 again, it is possible to return to the initial loading step shown in FIG.
[0033]
【The invention's effect】
As is apparent from the above description, according to the double-side polishing method and apparatus for a workpiece according to the present invention, the workpiece inserted in the thin plate carrier is sandwiched between the upper polishing plate and the lower polishing plate, and both polishing plates are rotated. The upper and lower surfaces of the workpiece are polished simultaneously.
[0034]
Then, after polishing is completed, the upper polishing plate and the carrier are pulled up to leave the workpiece on the lower polishing plate, and the workpiece left in the mounting state is moved into the workpiece storage cassette by the unloading arm in contact with the end surface. To be stored.
[0035]
Therefore, in the unloading step, the technical problem that the unloading arm does not touch the polished surface of the workpiece and leaves scratches due to the conveyance on the polished surface of the workpiece can be solved.
Therefore, the defect rate of the workpiece can be kept low, and the productivity of the semiconductor can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a state in which a semiconductor wafer is loaded in a double-side polishing apparatus according to the present invention.
2 is a cross-sectional view showing a state in which a semiconductor wafer is double-side polished by the apparatus shown in FIG.
3 is a cross-sectional view showing a state in which a semiconductor wafer is unloaded in the apparatus shown in FIG.
4 is a perspective view showing a form of a thin plate carrier used in the apparatus shown in FIG. 1. FIG.
5 is a top view for explaining an unloading state of the semiconductor wafer in FIG. 3. FIG.
[Explanation of symbols]
1 Upper polishing plate 2 Support shaft 3 Polishing cloth 5 Actuator for driving (motor)
8 Polishing plate moving mechanism 9 Carrier moving mechanism 10 Carrier holding disk 13 Engagement element 14 Lower polishing plate 15 Support shaft 16 Polishing cloth 18 Actuator for driving (motor)
21 Carrier drive board 23 Actuator for driving (motor)
25 Carrier 25a Insertion hole 26 Tension plate 27 Workpiece (semiconductor wafer)
28 Loading section 29 Loading arm 31 Work storage cassette 32 Unloading section 33 Unloading arm 35 Work storage cassette

Claims (5)

The upper polishing plate and the lower polishing plate sandwich the work inserted into the carrier, rotate both the upper and lower polishing plates to simultaneously polish the upper and lower surfaces of the work, and separate the upper polishing plate and the lower polishing plate from each other A step of moving the carrier to the upper polishing plate side to leave the workpiece on the lower polishing plate, and a step of placing the workpiece left on the lower polishing plate on the periphery of the workpiece. And a step of storing the workpiece in a workpiece storage cassette by an unloading arm in contact with an end surface of the side edge . An upper polishing plate that is rotationally driven by a driving actuator; a lower polishing plate that is rotationally driven by a driving actuator; a carrier that is disposed between the upper polishing plate and the lower polishing plate and into which a workpiece is inserted; and A polishing plate moving mechanism for separating the upper polishing plate and the lower polishing plate, and a carrier movement for moving the carrier toward the upper polishing plate in a state where the upper polishing plate and the lower polishing plate are separated by the polishing plate moving mechanism. A workpiece comprising: a mechanism; and an unloading arm that stores the workpiece left on the lower polishing plate in a workpiece storage cassette in contact with a peripheral edge surface of the workpiece. Double-side polishing equipment.   3. The double-side polishing apparatus for a workpiece according to claim 2, wherein the unloading arm has a shape corresponding to a peripheral edge surface of the workpiece to be polished.   The carrier is held at its peripheral side by a tension plate, and the tension plate is rotationally driven by a drive actuator, and the center position of the insertion hole into which the workpiece is inserted is defined by the upper polishing plate and the lower polishing plate. 4. The workpiece double-side polishing apparatus according to claim 2, wherein the workpiece is eccentric with respect to the rotational axis of the workpiece.   The work double-side polishing apparatus according to any one of claims 2 to 4, wherein the work is a semiconductor wafer.

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