JPH1148126A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly precisely and properly polish a work by regulating smoothly pressing force of an upper surface plate against a lower surface plate with a simple constitution. SOLUTION: An upper surface plate supporting mechanism 12 is provided with a cylinder device 22 disposed in an upper portion of its base body with a vertically extendable piston rod 22a, a rotating plate 24 fitted rotatably around an axis of the piston rod 22a as a center in a lower end of the piston rod 22a, plural connecting rods 26 inserted into the plate 24 to move vertically, connected to an upper surface plate 20 in its lower end so as to rotate integrally the upper surface plate 20 and the rotating plate 24 around the axis as a center, and provided in its end side with coming-off preventing parts 26a for preventing coming-off from the rotating plate 24, and a coil spring 28 fitted between each coming-off preventing part 26a of the connecting rod 26 and the rotating plate 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-side polishing apparatus, and more particularly, to a lower platen for supporting a work and an upper platen supported by an upper platen support mechanism capable of adjusting the pressing force applied to the lower platen. The present invention relates to a polishing apparatus for polishing a work by clamping a work between the work table and an upper surface plate, a lower surface plate and the work relative to each other.

[0002]

2. Description of the Related Art There is a lapping apparatus as a polishing apparatus for polishing a thin plate-like workpiece such as a silicon wafer, and a polishing apparatus as a polishing apparatus for polishing a polished surface of a workpiece to a mirror surface. For example, in a wrapping device, an external gear that is a sun gear (hereinafter, “external gear”)
By rotating the internal gear (hereinafter referred to as “internal gear”) at different angular velocities, the workpiece (hereinafter, referred to as “internal gear”) is rotated.
The carrier holding the "work" in the through hole is rotated and revolved. The carrier corresponds to a planetary gear. The work is sandwiched from above and below by upper and lower polishing platens provided above and below the carrier (hereinafter, the upper polishing platen is referred to as “upper platen” and the lower polishing platen is referred to as “lower platen”). Then, a slurry (polishing liquid) is supplied between the upper and lower lapping plates and the work, and each lapping plate relatively moves (rotates and / or swings) with respect to the work to simultaneously polish both surfaces of the work. There is something to do. This lapping device is known as a so-called 4-way drive type double-side polishing device,
The work can be flattened and polished with high precision, and both sides of the work can be processed at the same time.
It is suitable for polishing a thin material such as a silicon wafer used as a material of a semiconductor chip.

A polishing apparatus is generally provided with a polishing surface formed by attaching a polishing cloth to an upper surface, a rotating surface plate, and a rotatable and vertically movable upper surface of the surface plate. And a holding device having a holding plate for closely contacting and holding the work. The platen corresponds to the lower platen, and the holding plate corresponds to the upper platen. According to this polishing apparatus, mirror polishing is performed by relatively moving the surface plate and the work while supplying the polishing liquid.

A specific example of a conventional wrapping device is as follows.
This will be described with reference to FIG. Reference numeral 20 denotes an upper surface plate, on the lower surface of which a polished surface for lapping a silicon wafer serving as the work 10 is formed, and a key 21 is mounted on the upper surface. 2
Reference numeral 2 denotes a cylinder device for air pressure or the like, which is provided above the portal frame 14. The upper platen 20 is suspended from the tip of a piston rod 22a of the cylinder device 22 via a rotary plate 23 and a connecting rod 27, and is rotatably supported. That is, the connecting portion 22 fixed to the rotating plate 23
By b, the rotating plate 23 and the upper platen 20 connected to the rod 22 via the connecting rod 27 are provided so as to be rotatable and not fall off while the rod 22 does not rotate. The upper platen 20 is provided so that the pressing force to the lower platen 30 based on its own weight can be increased or decreased by adjusting the lifting force by the cylinder device 22.

The upper platen 20 is inserted into a key groove of a driver 54 in which the key 21 is rotated by the power of a driving motor 70.
And is rotationally driven by the drive motor 70. At the lower part of the screw 54, a screw shaft 54a is suspended, and a shaft gear 54 provided at the lower end thereof is provided.
“b” meshes with a spindle gear 64 provided on the spindle 60 via an idle gear 63. With this power transmission mechanism, the power of the drive motor 70 is transmitted to the upper stool 20 via the turner 54. The reason why the upper platen 20 and the turner 54 are linked by the key 21 is that it is necessary to lift the upper platen 20 so that the space between the lower platen 30 and the upper platen 20 is wide at the time of supply / discharge of the work 10 or maintenance management. For.

An external gear 50 meshes with the carrier 40 and is driven to rotate. The external gear 50 is connected to a first hollow shaft 50a concentrically provided around a rotary shaft 54a, and a shaft gear 50 provided on the first hollow shaft 50a.
b denotes a spindle gear 65 provided on the spindle 60
Is engaged. The lower platen 30 is connected to a second hollow shaft 30a concentrically provided around the first hollow shaft 50a.
The shaft gear 30 b provided in the middle of the shaft 60 meshes with the spindle gear 61 provided on the spindle 60.

Reference numeral 52 denotes an internal gear, which meshes with the carrier 40 to rotate. A third hollow shaft 52a provided concentrically around the second hollow shaft 30a is connected to the internal gear 52, and a shaft gear 52b provided on the third hollow shaft 52a is connected to the spindle 60. It engages with the provided spindle gear 62. The spindle 60 is connected to a variable speed reducer 69, and the variable speed reducer 69 is connected to a drive motor 7 such as an electric motor or a hydraulic motor via a belt.
Connected to 0. Thereby, the upper stool 20, the lower stool 30, the external gear 50, the internal gear 52
The power is transmitted by the same drive motor 70 via the variable speed reducer 69, the gear train, and each shaft, respectively.
Had been driven to rotate.

According to the lapping apparatus having the above-described structure, as described above, the upper platen 20 increases or decreases the pressing force on the lower platen 30 based on its own weight by adjusting the lifting force by the cylinder device 22. It is provided as possible. That is, as the pressure fluid supplied to the lower pressure chamber is increased so as to operate the piston rod 22a to contract the cylinder body, the pressing force of the upper platen 20 against the lower platen 30 can be further reduced. . Therefore, as the pressing force on the lower stool 30 of the upper stool 20, the own weight of the upper stool 20 can be added at the maximum. In the polishing of the silicon wafer, when the surface of the silicon wafer has irregularities, a high-pressure fluid is supplied to the cylinder device 22 to reduce the pressing force of the upper platen 20 and lap the wafer. The pressure of the pressurized fluid supplied to the cylinder device 22 is gradually reduced, and
Increase the pressing force by 0. Then, after the surface of the silicon wafer becomes smooth and the thickness becomes uniform, and the silicon wafer receives a uniform load over the entire surface, adjustment is made so that the total weight of the upper platen 20 is applied. Wrapping is performed. At this time,
It is desirable that the adjustment of the pressing force by the upper surface plate 20 be performed accurately and smoothly.

[0009]

However, in the above lapping device, the pressing force by the upper platen 20 is directly adjusted by adjusting the pressurizing and depressurizing of the cylinder device 22, so that the internal resistance of the cylinder device 22 is reduced. Directly reflected, and it was difficult to make the fine adjustment linear. That is, the piston rod 22a
The pressing force of the upper platen 20 changes directly in accordance with the tensile stress of the upper platen 20. The pressure changes. Therefore, the cylinder device 22
The working stroke of the piston fixed to the upper end of the piston rod 22a in the grinding process during the grinding process is basically the total length of the grinding amount (the shaved thickness amount) of the work 10 and the minute elastic extension amount of the piston rod 22a. And very short. And, due to the frictional resistance between the piston and the inner wall of the cylinder, it is difficult for the piston to move completely smoothly, and the piston operates intermittently. This directly reflects on the pressing force of the upper stool 20. Therefore,
There is a problem that the pressing force of the upper platen 20 on the lower platen 30 cannot be adjusted smoothly. In addition, the phenomenon in which the piston intermittently operates while being engaged is called knocking or slip stick. Also, usually
The piston is slidably provided on the inner wall of the cylinder via a seal member, and deformation of the seal member due to pressure causes frictional resistance.

Further, it is difficult to make the lengths of the connecting rods 27 completely the same, and the load is partially concentrated even by a slight inclination due to a minute difference in the length of the connecting rods 27. As a result, the work cannot be uniformly polished. In particular, in polishing of silicon wafers, there is a problem that extremely high-precision polishing on the order of sub-microns is required, and it is not possible to cope with the extremely severe polishing conditions, such as an increase in the size of the entire apparatus as the size of the silicon wafer increases. Was.

Therefore, an object of the present invention is to provide a simple configuration,
An object of the present invention is to provide a polishing apparatus capable of suitably polishing a work with high accuracy by being able to smoothly adjust a pressing force applied to a lower surface plate of an upper surface plate.

[0012]

The present invention has the following configuration to achieve the above object. That is, the present invention provides a method of clamping a work between a lower platen supporting a work and an upper platen supported by an upper platen support mechanism capable of adjusting the pressing force to the lower platen, In a polishing apparatus for polishing a work by relatively moving a lower platen and a work, the upper platen support mechanism includes a cylinder device in which a piston rod is disposed on an upper portion of a base so as to be able to expand and contract in a vertical direction. A rotary plate mounted at the lower end of the piston rod of the cylinder device so as to be rotatable about the axis of the piston rod, and inserted through the rotary plate so as to be vertically movable, and the upper platen and the rotary plate A plurality of connecting rods, the lower end of which is connected to the upper surface plate and the upper end side of which is provided with a retaining portion for preventing the falling off from the rotating plate, and each of the connecting rods. Attached between the retaining part and the rotating plate And an elastic member, while supporting suspended the upper plate,
The pressing force to the lower surface plate based on the weight of the upper surface plate is increased and decreased by adjusting the lifting force by the cylinder device.

[0013] Further, since the plurality of connecting rods are provided at equally spaced positions on the circumference centered on the axis of the piston rod of the cylinder device, a simple structure using a plurality of the same members can be more uniformly provided. Work can be polished.

Further, since the elastic member is a coil spring, the effective stroke of the vertical movement of the rod of the cylinder device, which affects the pressing force by the upper platen, can be significantly increased by the contraction stroke. Workpieces can be polished with extremely high precision by smoothly adjusting the pressing force by the surface plate.

A polishing surface for polishing a work is formed on each of the upper surface of the lower platen and the lower surface of the upper platen. By polishing both surfaces of the work at the same time, it is suitable for a double-side polishing apparatus. Applicable. Further, the work is in the form of a thin plate, and by lapping both surfaces of the work in the form of a thin plate at the same time, the present invention can be suitably applied to a lapping apparatus for thin objects such as silicon wafers.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front view showing an embodiment (mainly an upper platen support mechanism) according to the present invention. FIG. 2 is a plan view illustrating the upper platen support mechanism of the embodiment of FIG. This embodiment is a lapping apparatus as an example of a polishing apparatus for simultaneously polishing both surfaces of a silicon wafer. The lapping apparatus includes a lower platen 30 supporting a silicon wafer (work 10) and an upper platen 20 supported by an upper platen support mechanism 12 capable of adjusting the pressing force applied to the lower platen 30. Workpiece 10 is clamped, upper surface plate 2
The lower platen 30 and the work 10 are relatively moved to polish both surfaces of the work 10. The external gear 5 that drives the upper stool 20, the lower stool 30, and the carrier 40
The drive mechanism for the 0 and the internal gear 52 is the same as that of the prior art shown in FIG.

The upper platen support mechanism 12 has the following configuration. Reference numeral 22 denotes a cylinder device. The piston rod 2 is provided at the center of the beam of the portal frame 14, which is the upper part of the base.
2a is provided so as to be able to expand and contract in the vertical direction. Although the cylinder device 22 of the present embodiment operates by air pressure supplied from a compressed air source (not shown), other fluid pressures (for example, water pressure,
(Oil pressure). Reference numeral 24 denotes a rotary plate, which is attached to the lower end of the piston rod 22a of the cylinder device 22 so as to be rotatable around the axis of the piston rod 22a. As shown in FIGS. 1 and 2, it is formed in a circular flat plate. It is to be noted that a hollow portion may be appropriately provided to reduce the weight, and a rib or the like may be appropriately formed to increase rigidity.

Reference numeral 26 denotes a connecting rod, which is vertically movably inserted through the rotating plate 24 so that the upper platen 20 and the rotating plate 24 rotate integrally about the axis of the piston rod 22a.
The lower end is connected to the upper platen 20. The upper end is provided with a retaining portion 26a for preventing dropping from the rotating plate 24. In this embodiment, a connecting rod 26 is inserted into a through hole 24a formed in the rotary plate 24, and connects the rotary plate 24 and the upper platen 20 to each other. Further, as shown in FIG. 2, in this embodiment, twelve connecting rods 26 are provided.
Are provided at equally spaced angular positions around the axis of the piston rod 22a and the rotating plate 24, respectively.

Reference numeral 28 denotes a coil spring, which is an example of an elastic member mounted between each retaining portion 26a of the connecting rod 26 and the upper surface of the rotary plate 24. According to the upper platen support mechanism 12 provided by the above configuration, the upper platen 20
And presses the lower platen 30 based on the weight of the upper platen 20 against the lower platen 30, and applies the cylinder device 2 to the upper platen 20.
By adjusting the lifting force according to 2, the pressure can be suitably increased and decreased. The connecting rod 26 and the coil spring 28
Need not be twelve, but may be increased or decreased as long as it is plural.

Since the present embodiment is a lapping apparatus, a polishing surface for polishing the work 10 is formed on the upper surface of the lower platen 30 and the lower surface of the upper platen 20, respectively.
Both surfaces of the work 10 can be polished simultaneously. Thus, according to the present embodiment, both sides of the silicon wafer (work 10) formed of a thin plate-shaped brittle material can be wrapped with high precision and efficiency.

Next, a description will be given of a use state and an operation effect of this embodiment. First, when the work 10 is set on the polishing surface of the lower platen 30 in the through hole of the carrier 40, a sufficient space is formed between the work 10 and the lower platen 30 by contracting the piston rod 22a of the cylinder device 22. The upper platen 20 is pulled up as soon as possible. At this time, the entire weight of the upper stool 20 is received by the plurality of coil springs 28. Therefore, each coil spring 28 is in the most contracted state. The number of holes in the carrier 40 per sheet is usually 5 or more, and the work 10 is held in each of the holes. The carrier 40
Is usually 4 to 5 pieces per apparatus, so that 20 or more workpieces 10 can be polished at the same time.

Then, the air in the cylinder device 22 is decompressed to lower the upper platen 20, and the polished surface of the upper platen 20 is brought into contact with the upper surface of the work 10. The polished surface of the work 10 (silicon wafer) has irregularities before lapping, and when a high load is applied by the upper stool 20, the load is concentrated on the convex portion of the work 10, and the work 10 is broken. I will.
Therefore, when the lapping of the work 10 is started, the air pressure supplied to the cylinder device 22 is in a high state (for example, 5 k).
gf / cm ² ), and the load applied to the work 10 is low. Further, the weight applied to the plurality of coil springs 28 at this time is obtained by subtracting the weight applied to the work 10 from the weight of the upper platen 20. Each coil spring 28 is in a slightly expanded state from the most contracted state.

Next, the pressure of the air pressure supplied to the cylinder device 22 is gradually reduced, and the work 1
The work 10 is wrapped while increasing the pressing force to the zero side. The driving method of the external gear 50 and the internal gear 52 for driving the upper platen 20, the lower platen 30, and the carrier 40 when lapping the work 10 is the same as that of the related art shown in FIG. Omitted. After the surfaces to be polished of the work 10 become somewhat smooth and have a uniform thickness, and the work 10 is subjected to a uniform load over the entire surface, the entire weight of the upper platen 20 or a series of The pressure of the air pressure supplied to the cylinder device 22 is adjusted so that the maximum load is applied in the polishing process. When applying the total weight, which is the maximum weight of the upper stool 20, to the work 10, the air pressure may be reduced to zero.

As described above, while the pressure of the air pressure supplied to the cylinder device 22 is gradually reduced, the load applied to the coil spring 28 is converted into the load applied to the work 10 and gradually reduced. You. Therefore, the coil spring 28 gradually expands. The length of extension of the coil spring 28 corresponds to the stroke in which the piston rod 22a of the cylinder device 22 projects (extends). That is, the effective stroke of the piston rod 22a is basically the same as the length of the expansion and contraction stroke of the coil spring 28. Compared to the prior art of FIG. 3, the effective stroke can be made very long. For this reason, it is possible to perform a predetermined pressure change in a long effective stroke, and it is hard to be affected by the internal resistance generated between the piston of the cylinder device 22 and the inner wall of the cylinder body. The pressing force can be changed smoothly.
Therefore, high-precision polishing can be suitably performed.

Further, even if the length of the plurality of connecting rods 26 varies (error), the plurality of coil springs 28
, The load is suitably distributed to each coil spring 28, and the work 10 can be pressed uniformly. This is because the length of the expansion / contraction stroke of the coil spring 28 is much longer than the length of the error, and a slight variation in the length of the connecting rod 26 is easily absorbed. That is, when the plurality of rods 26 are simply connected, the longest connecting rod 2 may be used, for example, when the polishing surface of the upper platen 20 is brought into contact with the surface to be polished of the work 10.
Although it is conceivable that the load is intensively applied from No. 6, when the plurality of coil springs 28 are used as in the present embodiment, the load can be appropriately dispersed. Further, the upper platen 20 can be suspended with a good horizontal balance by the plurality of coil springs 28, and a biased force is not applied to the piston in the cylinder device 20. Therefore, the upper platen is hardly affected by the internal resistance of the cylinder device 22 described above.
The pressing force by 0 can be changed stably and smoothly. Therefore, high-precision polishing can be suitably performed.

By the way, the connecting rod 26 of the above embodiment is used.
Is simply inserted through the through-hole 24a, but may be inserted through the rotary plate 24 via a linear bush, a spherical bearing, or a bearing in which both are integrated. If the linear bush is used, the movement in the thrust direction can be smoothly received, and the spherical bearing can suitably cope with the inclination of the connecting rod 26. Further, needless to say, a stopper means for restricting the movement of the connecting rod 26 in the thrust direction (vertical direction) to a predetermined range may be provided.

Further, in the above embodiment, the coil spring 28 is used as the elastic member. However, the present invention is not limited to this, and it is also possible to use elastic means using a pressurized fluid such as an airbag or a rubber material. In the case of an airbag or the like, since the airbag or the like is mounted on the rotating rotary plate 24, the structure is complicated, such as requiring a distributor to supply a pressurized fluid such as compressed air. In the case of a rubber material, unlike the coil spring 28, it is difficult to take a long expansion / contraction stroke.

In the above embodiment, the portal frame 14 is used as the base for suspending the upper platen 20, but the form of the base (frame) is not limited to this.
A form such as an inverted L-shape may be used. However, the portal frame 14
Has advantages such as being able to withstand high loads. In the above embodiment, the drive sources of the upper stool 20, the lower stool 30, and the carrier 40 are connected to one drive motor 70 (see FIG. 3).
However, the present invention is not limited to this.
Of course, each of them may be driven separately. In the above embodiment, the double-sided lapping apparatus has been described as a polishing apparatus. However, the present invention is not limited to this. For example, a workpiece can be suitably mirror-polished with an equivalent configuration in a polishing apparatus. As described above, the present invention has been described variously with reference to preferred embodiments. However, the present invention is not limited to the embodiments, and it is needless to say that many modifications can be made without departing from the spirit of the invention. That is.

[0029]

According to the present invention, between each retaining portion of the connecting rod connecting the rotary plate and the upper platen, and the rotary plate rotatably mounted at the lower end of the piston rod of the cylinder device, By attaching the elastic member, the pressing force to the lower stool based on the weight of the upper stool can be appropriately increased or decreased by adjusting the lifting force by the cylinder device. That is,
By suitably interposing the elastic member, the effective expansion and contraction stroke of the piston rod of the cylinder device can be increased, and the pressing force of the upper stool against the lower stool can be changed stably and smoothly. Thus, according to the present invention,
Although it has a simple configuration, it has a remarkable effect that the work can be suitably polished with high accuracy.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing an embodiment of a wrapping device according to the present invention.

FIG. 2 is a plan view illustrating an upper platen support mechanism of the embodiment of FIG.

FIG. 3 is a front sectional view of a conventional wrapping device.

DESCRIPTION OF SYMBOLS 10 Work 12 Upper platen support mechanism 14 Gate frame 20 Upper platen 22 Cylinder device 22a Piston rod 24 Rotating plate 26 Connecting rod 26a Retaining stopper 28 Coil spring 30 Lower platen

Claims (5)

[Claims] 1. A work is clamped between a lower platen supporting a work and an upper platen supported by an upper platen support mechanism capable of adjusting a pressing force applied to the lower platen. A polishing apparatus for polishing a work by relatively moving a lower platen and a work, wherein the upper platen support mechanism comprises: a cylinder device having a piston rod disposed on an upper portion of a base so as to be vertically expandable and contractible; A lower end of the piston rod of the apparatus, a rotating plate rotatably mounted about the axis of the piston rod, and a vertically movable plate inserted through the rotating plate, and the upper platen and the rotating plate A plurality of connecting rods, the lower end of which is connected to the upper surface plate so as to rotate integrally with the center, and the upper end side of which is provided with a retaining portion for preventing falling off from the rotating plate; Mounted between the stop and the rotating plate A polishing member comprising: a supporting member for suspending and supporting the upper platen; and a pressing force applied to the lower platen based on the weight of the upper platen, which is adjusted by adjusting a lifting force by a cylinder device. . 2. The polishing apparatus according to claim 1, wherein the plurality of connecting rods are provided at equal angular positions on a circumference around the axis of a piston rod of the cylinder device. 3. The polishing apparatus according to claim 1, wherein the elastic member is a coil spring. 4. A polishing surface for polishing a work is formed on an upper surface of the lower platen and a lower surface of the upper platen, respectively, and both surfaces of the work are simultaneously polished. 4. The polishing apparatus according to 2 or 3. 5. The polishing apparatus according to claim 4, wherein the work has a thin plate shape, and both surfaces of the thin plate work are wrapped at the same time.