JP3573924B2 - Polishing equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a double-side polishing apparatus, and more specifically, 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. The present invention relates to a polishing apparatus that grinds a work by relatively moving an upper surface plate, a lower surface plate, and a work while pressing the work surface.
[0002]
[Prior 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 lapping device, a workpiece (hereinafter, “workpiece”) is rotated by rotating an external gear (hereinafter, “external gear”), which is a sun gear, and an internal gear (hereinafter, “internal gear”) at different angular velocities. Is rotated and revolved around the carrier held in the through hole. 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 four-way drive type double-side polishing device, and can flatten and polish a work with high accuracy, and can simultaneously process both surfaces of the work, so that the processing time is short and the material of the semiconductor chip is reduced. It is suitable for polishing thin materials such as silicon wafers.
[0003]
In addition, a polishing apparatus is generally provided with a polishing surface formed by bonding a polishing cloth to an upper surface, a rotating surface plate, and a rotatable and vertically movable member provided above the surface plate, and a work on a lower surface. And a holding device having a holding plate for closely contacting and holding. The platen corresponds to the lower platen, and the holding plate corresponds to the upper platen. According to this polishing apparatus, mirror surface polishing is performed by relatively moving the surface plate and the work while supplying the polishing liquid.
[0004]
A specific example of a conventional lapping device 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. Reference numeral 22 denotes a pneumatic cylinder device 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, with the connecting portion 22b fixed to the rotating plate 23, the rotating plate 23 and the upper stool 20 linked to the rod 22 via the connecting rod 27 can rotate with the rod 22 not rotating. It is provided so as not to fall off. 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.
[0005]
The upper platen 20 is inserted into and engaged with a key groove of a driver 54 in which the key 21 is rotated by the power of the drive motor 70, and is driven to rotate by the drive motor 70. A turn shaft 54a is vertically provided below the turn 54, and a shaft gear 54b provided at a lower end thereof meshes with a spindle gear 64 provided on the spindle 60 via an idle gear 63. . With this power transmission mechanism, the motive power of the drive motor 70 is transmitted to the upper stool 20 via the driver 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 lower platen 30 is wide at the time of supply and discharge of the work 10 or maintenance management. For.
[0006]
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 provided concentrically around a rotary shaft 54a, and a shaft gear 50b provided on the first hollow shaft 50a is provided on a spindle 60. The gear is engaged with the spindle gear 65.
A second hollow shaft 30a concentrically provided around the first hollow shaft 50a is connected to the lower platen 30, and a shaft gear 30b provided in the middle of the second hollow shaft 30a is connected to a spindle. The gear 60 meshes with a spindle gear 61 provided on the shaft 60.
[0007]
An internal gear 52 meshes with the carrier 40 and is driven to rotate. A third hollow shaft 52a concentrically provided 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 is engaged 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 via a belt to a drive motor 70 such as an electric motor or a hydraulic motor.
As a result, the upper platen 20, the lower platen 30, the external gear 50, and the internal gear 52 receive power from the same drive motor 70 via the variable speed reducer 69, the gear train, and each shaft, and rotate. Had been driven.
[0008]
According to the lapping device having such a configuration, as described above, the upper platen 20 is provided with a pressing force to the lower platen 30 based on its own weight so as to be able to increase and decrease the pressure by adjusting the lifting force by the cylinder device 22. Has been. 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 surface plate 30 of the upper surface plate 20, the own weight of the upper surface plate 20 can be applied 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 and the pressing force of the upper stool 20 is reduced to perform lapping. The pressure of the pressurized fluid supplied to the cylinder device 22 is gradually reduced, and the pressing force by the upper stool 20 is increased. 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. Lapping is performed. At this time, it is desirable that the adjustment of the pressing force by the upper stool 20 be performed accurately and smoothly.
[0009]
[Problems to be solved by the invention]
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 influence of the internal resistance of the cylinder device 22 is directly reflected. As a result, it was difficult to make the fine adjustment linear.
That is, the pressing force of the upper platen 20 directly changes in accordance with the tensile stress of the piston rod 22a, and when the polishing surface, which is the lower surface of the upper platen 20, comes into contact with the workpiece 10, The pressing force by the platen 20 changes. Therefore, the working stroke of the piston fixed to the upper end of the piston rod 22a in the cylinder device 22 during the polishing process basically includes the polishing amount (the shaving thickness amount) of the work 10 and the minute elastic extension amount of the piston rod 22a. , Which is 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 interlocking is called knocking or slip stick. 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.
[0010]
Further, it is difficult to make the lengths of the connecting rods 27 completely the same, and even if the load is partially concentrated due to a slight inclination due to a minute difference in the length of the connecting rods 27, Cannot be uniformly polished. In particular, in polishing of silicon wafers, there is a problem that extremely high-precision polishing on the order of submicrons is required, and the size of the entire apparatus is increased with the enlargement of silicon wafers. Was.
[0011]
Therefore, 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 the pressing force to the lower platen with a simple configuration.
[0012]
[Means for Solving the Problems]
The present invention has the following configuration to achieve the above object.
That is, the present invention presses the work between the lower stool supporting the work and the upper stool supported by the upper stool support mechanism , and relatively moves the upper stool, the lower stool and the work. In a polishing apparatus for polishing a work, the upper platen support mechanism is disposed on an upper portion of a base, a cylinder device in which a piston rod is provided so as to be able to expand and contract in a vertical direction, and at a lower end of a piston rod of the cylinder device, A rotary plate rotatably mounted about the axis of the piston rod, and a plurality of through holes provided at regular intervals on a circumference of the rotary plate about the axis of the rotary plate; The lower end is connected to the upper surface plate and rotated to the upper end side so that the upper surface plate and the rotating plate are integrally rotated about the axis so that the upper surface plate and the rotating plate rotate integrally with each other. connecting rod which retaining portion is prevented from falling off from the plate is provided If the is the retaining portion of the connecting rod and mounted between the rotary plate, and an elastic member hanging good horizontal balance the over platen, by the upper surface plate support mechanism, hanging the upper plate The workpiece is polished by applying a load of a difference between the weight of the upper stool and the load applied to the elastic member or the total weight of the upper stool to the work while being lowered and supported. And
[0013]
Preferably, a linear bush is provided in the through hole, and the connecting rod is inserted through the linear bush.
[0014]
Further, the elastic member is a coil spring, so that the effective stroke of the vertical movement of the rod of the cylinder device applied to the adjustment of the pressing force by the upper platen can be drastically increased by the contraction stroke thereof. Workpieces can be polished with extremely high precision by adjusting the pressing force smoothly.
[0015]
A polishing surface for polishing a work is formed on each of the upper surface of the lower surface plate and the lower surface of the upper surface plate. By polishing both surfaces of the work at the same time, the present invention can be suitably applied to a double-side polishing apparatus.
Further, the work is in the form of a thin plate, and by lapping both sides 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 a thin object such as a silicon wafer.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a front view showing one embodiment (mainly an upper surface plate supporting 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. The work 10 is sandwiched and the upper surface plate 20, the lower surface plate 30, and the work 10 are relatively moved to polish both surfaces of the work 10. The driving mechanism of the external gear 50 and the internal gear 52 for driving the upper stool 20, the lower stool 30, and the carrier 40 is the same as that of the prior art shown in FIG.
[0017]
The upper platen support mechanism 12 has the following configuration.
Reference numeral 22 denotes a cylinder device, and a piston rod 22a is provided at the center of the beam of the portal frame 14, which is the upper part of the base, so as to be able to expand and contract in the vertical direction. Although the cylinder device 22 of the present embodiment is operated by air pressure supplied from a compressed air source (not shown), it may be operated by another fluid pressure (for example, water pressure or 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 about 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 the rigidity.
[0018]
Reference numeral 26 denotes a connecting rod, which is vertically movably inserted into the rotating plate 24, and whose lower end is connected to the upper surface plate 20 so that the upper surface plate 20 and the rotating plate 24 rotate integrally about the axis of the piston rod 22a. Have been. The upper end portion is provided with a retaining portion 26a that prevents the rotating plate 24 from falling off. In the present embodiment, a connecting rod 26 is inserted through a through hole 24 a formed in the rotary plate 24, and connects the rotary plate 24 and the upper surface plate 20.
Further, as shown in FIG. 2, in the present embodiment, twelve connecting rods 26 are provided at equally spaced angular positions around the axis of the piston rod 22a and the rotating plate 24, respectively.
[0019]
Reference numeral 28 denotes a coil spring, which is an example of an elastic member mounted between each retaining portion 26 a of the connecting rod 26 and the upper surface of the rotating plate 24.
According to the upper stool support mechanism 12 provided by the above configuration, the upper stool 20 is suspended and supported, and the pressing force to the lower stool 30 based on the weight of the upper stool 20 is applied to the upper stool 20. By adjusting the lifting force by the cylinder device 22, pressure can be suitably increased and decreased.
The number of connecting rods 26 and coil springs 28 need not be 12, but may be increased or decreased as long as the number is plural.
[0020]
In addition, since the present embodiment is a lapping device, a polishing surface for polishing the work 10 is formed on each of the upper surface of the lower platen 30 and the lower surface of the upper platen 20, and both surfaces of the work 10 are simultaneously polished. be able to. 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.
[0021]
Next, a use state and an operation effect of the present embodiment will be described.
First, when the work 10 is set on the polished surface of the lower platen 30 in the through hole of the carrier 40, a sufficient space is provided 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 lifted 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. Note that the number of through holes of the carrier 40 per sheet is usually five or more, and the work 10 is held in each of the through holes. Further, since the number of the carriers 40 is usually 4 to 5 per apparatus, 20 or more works 10 can be polished at the same time.
[0022]
Then, the air in the cylinder device 22 is depressurized to lower the upper platen 20, and the polishing 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 platen 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 kgf / cm ² ), and the load applied to the work 10 is in a low state. The load applied to the plurality of coil springs 28 at this time is obtained by subtracting the load 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.
[0023]
Next, the work 10 is wrapped while the pressure of the air pressure supplied to the cylinder device 22 is gradually reduced to increase the pressing force of the upper surface plate 20 toward the work 10. 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.
Then, after the surfaces to be polished of the work 10 become somewhat smooth and the thickness becomes uniform, and the work 10 receives a uniform load over the entire surface, the total 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 load becomes the maximum in the polishing process. When applying the total weight, which is the maximum load by the upper stool 20, to the work 10, the air pressure may be reduced to zero.
[0024]
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 to the load applied to the work 10 and gradually reduced. 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. The effective stroke can be made very long as compared with the prior art of FIG.
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.
[0025]
Further, even if the lengths of the plurality of connecting rods 26 vary (errors), the load is appropriately distributed to the coil springs 28 and the work 10 can be pressed uniformly because the plurality of connecting rods 26 have variations (errors). . 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 a plurality of rods 26 are simply connected, the load is concentrated from the longest connecting rod 26 when the polishing surface of the upper platen 20 is brought into contact with the surface to be polished of the work 10. However, when a plurality of coil springs 28 are interposed as in the present embodiment, the load can be appropriately dispersed.
Further, the upper platen 20 can be suspended with 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. For this reason, it is hard to be affected by the internal resistance of the cylinder device 22 described above, and the pressing force by the upper platen 20 can be changed stably and smoothly. Therefore, high-precision polishing can be suitably performed.
[0026]
By the way, the connecting rod 26 of the above embodiment 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, stopper means for restricting the movement of the connecting rod 26 in the thrust direction (vertical direction) within a predetermined range may be provided.
[0027]
Further, in the above-described 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 pressure 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 that a distributor is required 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.
[0028]
In the above embodiment, the portal frame 14 is used as the base for suspending the upper stool 20. However, the form of the base (frame) is not limited to this, and may be an inverted L-shape or the like. . However, the portal frame 14 has advantages such as being able to withstand a high load.
Further, in the above embodiment, the case where the drive sources of the upper stool 20, the lower stool 30 and the carrier 40 are assumed to be one drive motor 70 (see FIG. 3) has been described, but the present invention is not limited to this. May be driven separately.
Further, in the above embodiment, the double-sided lapping apparatus has been described as the polishing apparatus. However, the present invention is not limited to this. For example, a workpiece can be suitably mirror-polished with the same configuration in a polishing apparatus.
As described above, the present invention has been described variously with reference to the preferred embodiments. However, the present invention is not limited to these embodiments, and it is needless to say that many modifications can be made without departing from the spirit of the invention. That is.
[0029]
【The invention's effect】
According to the present invention, an elastic member is mounted between each retaining portion of the connecting rod connecting the rotary plate and the upper surface plate, and the rotary plate rotatably mounted on the lower end of the piston rod of the cylinder device. Thus, the pressing force to the lower stool based on the weight of the upper stool can be suitably increased or decreased by adjusting the lifting force by the cylinder device. That is, the effective expansion and contraction stroke of the piston rod of the cylinder device can be lengthened by suitably interposing the elastic member, and the pressing force of the upper surface plate on the lower surface plate can be changed stably and smoothly.
Therefore, according to the present invention, although having a simple configuration, there is a remarkable effect that a workpiece can be suitably polished with high accuracy.
[Brief description of the drawings]
FIG. 1 is a front sectional view showing one 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.
[Explanation of symbols]
Reference Signs List 10 Work 12 Upper platen support mechanism 14 Gate type frame 20 Upper platen 22 Cylinder device 22a Piston rod 24 Rotating plate 26 Connecting rod 26a Retaining portion 28 Coil spring 30 Lower platen

Claims (5)

A polishing apparatus for clamping a work between a lower platen supporting a work and an upper platen supported by an upper platen support mechanism , and relatively moving the upper platen, the lower platen and the work to polish the work. At
The upper platen support mechanism,
A cylinder device arranged on the upper part of the base body , wherein the piston rod is provided so as to be able to expand and contract in the vertical direction;
A rotating plate attached to the lower end of the piston rod of the cylinder device so as to be rotatable around the axis of the piston rod;
The rotating plate is provided so as to be vertically movable through respective through holes of a plurality of through holes provided at regular intervals on a circumference around the axis of the rotating plate. A connection rod , wherein each lower end is connected to the upper surface plate, and a stopper portion is provided on each upper end side to prevent the rotation plate from falling off, such that the rotation is integrally performed around the axis.
An elastic member mounted between each of the retaining portions of the connecting rod and the rotating plate, and suspending the upper surface plate in a well-balanced manner,
The upper stool support mechanism suspends the upper stool and supports the upper stool to abut on a work. The work has a difference between the weight of the upper stool and the load applied to the elastic member, or the upper stool. A polishing apparatus characterized in that the work is polished by applying its own weight . The polishing apparatus according to claim 1 , wherein a linear bush is provided in the through hole, and the connecting rod passes through the linear bush . 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 each of an upper surface of the lower platen and a lower surface of the upper platen, and both surfaces of the work are simultaneously polished. Polishing equipment. 5. The polishing apparatus according to claim 4, wherein the work is a thin plate, and both sides of the thin plate are wrapped at the same time.

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