JP2012192486A - Double surface polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double surface polishing device capable of accurately and stably fine-tuning a pressing force applied to a workpiece at polishing from an upper surface plate by means of a pressure reducing mechanism which can reduce energy consumption in a simple structure.SOLUTION: The double surface polishing device has the pressure reducing mechanism 44 for making a load having a reverse direction with the load of the upper surface plate 3 act on the upper surface plate 3 at the polishing of the workpiece W where a difference between the load of the upper surface plate 3 and the reverse load is set up to be pressed pressure at polishing. The pressure reducing mechanism 44 has a static pressure transmission shaft 45 arranged in a vertically movable state at a position where an axis is coincident with the upper surface plate 3, a self-aligning bearing 49 for mutually connecting the upper surface plate 3 and the static pressure transmission shaft 45, and a static pressure generator 48 for generating static pressure generated by a liquid level difference of a standstill liquid 47 and acting the static pressure to the static pressure transmission shaft 45 as a reverse load to the load generated by the upper surface plate 3.

Description

  The present invention relates to a double-side polishing apparatus capable of finely adjusting a pressing force applied by an upper surface plate applied to a workpiece during polishing.

  A double-side polishing apparatus that polishes both sides of a workpiece is generally an annular upper and lower surface plate disposed concentrically, a sun gear disposed in the center of the lower surface plate, An internal gear disposed so as to surround the outer periphery, and a carrier disposed on the lower surface plate and meshing with the sun gear and the internal gear, and a work held by the carrier The upper surface plate and the lower surface plate are relatively sandwiched between the upper surface plate and the lower surface plate, while rotating the sun gear and the internal gear to rotate the carrier and revolve around the sun gear. And both surfaces of the workpiece are polished.

  During polishing, a pressing force (processing load) is applied to the workpiece by an upper surface plate. In that case, the weight (load) of the upper surface plate is very large including the weight of the attached member. Therefore, it is necessary to adjust the weight of the upper surface plate according to the processing conditions of the workpiece. In the case of polishing a workpiece that is easily damaged, it is necessary to polish the workpiece while applying a small pressing force finely adjusted precisely to the entire workpiece. For this reason, generally, a reduced pressure generation mechanism that generates a load (reverse load) opposite to the load of the upper surface plate is provided, and by applying a reverse load from the reduced pressure generation mechanism to the upper surface plate, The difference between the load on the upper surface plate and the reverse load is used as the pressing force during polishing.

Patent Literature 1 to Patent Literature 4 disclose polishing apparatuses equipped with various configurations of reduced pressure generating mechanisms.
The depressurization generation mechanism of the polishing apparatus described in Patent Document 1 generates a reverse load with a weight and opposes the weight of the upper platen. However, depending on the structure, it is approximately the same as the weight of the upper platen. Since the weight of the weight must be provided, the total weight of the polishing device becomes very large and the device becomes large, and a mechanism for moving the weight and adjusting it to adjust the reverse load is required. The structure is also complicated.

  Further, the depressurization generating mechanism of the polishing apparatus described in Patent Document 2 and Patent Document 3 uses an airbag and adjusts the pressing force of the upper surface plate by adjusting the air pressure in the airbag. . However, in the case of using an air bag in this way, an air pump, a solenoid valve, or the like is necessary to supply / discharge compressed air to / from the air bag, and power is always required when the air pump or the solenoid valve is driven. Therefore, there is a problem that the structure is complicated and the energy consumption is large. Furthermore, since the compressed air is suddenly supplied to or discharged from the airbag by turning on and off the solenoid valve, the pressure inside the airbag is greatly increased and decreased, and the upper surface plate is unstable. When a reverse load is applied, the pressing force becomes unstable, and this tends to damage the workpiece.

  Further, the depressurization generating mechanism of the polishing apparatus described in Patent Document 4 supports the weight of the upper surface plate by an upper surface plate lifting shaft arranged concentrically with the upper surface plate, The pressing force of the upper surface plate is adjusted by raising and lowering with two fluid pressure cylinders, two sets of fluid generators (pumps) and a fluid control valve. However, this polishing apparatus not only has a problem that the structure of the decompression generation mechanism is complicated and consumes a large amount of energy such as electric power, but also the fluid control valve is turned on and off to bring the pressure fluid into the fluid pressure cylinder. Since pressure fluctuations are likely to occur during the feeding of the steel plate, an unstable reverse load acts on the upper surface plate, which tends to cause damage to the workpiece.

JP 2007-83328 A Japanese Patent Laid-Open No. 10-264012 Japanese Unexamined Patent Publication No. 2000-6005 Japanese Patent Laid-Open No. 2001-322062

  The technical problem of the present invention is to make it possible to finely and stably finely adjust the pressing force applied by the upper surface plate applied to the workpiece during the polishing process with a pressure reducing mechanism having a simple configuration and low energy consumption.

  In order to solve the above-mentioned problems, the present invention provides an upper surface plate and a lower surface plate that can be driven and rotated while sandwiching a workpiece, an upper surface plate elevating mechanism that raises and lowers the upper surface plate, and the upper surface plate when polishing a workpiece. In a double-side polishing apparatus having a pressure reducing mechanism that acts on the upper surface plate in a direction opposite to that of the load, and using a difference between the load of the upper surface plate and the load by the pressure reducing mechanism as a pressing force during polishing, The pressure reducing mechanism includes a static pressure transmission shaft arranged to move up and down at a position where the axis line coincides with the upper surface plate, and an automatic centering bearing that interconnects the upper surface plate and the static pressure transmission shaft. A static pressure generating device that generates a static pressure due to a difference in liquid level of a stationary liquid and causes the static pressure to act on the static pressure transmission shaft as a load opposite to the load by the upper surface plate. To do.

  In the present invention, the static pressure generator includes a pressure receiving member connected to the static pressure transmission shaft, a volume variable static pressure working chamber that applies a static pressure to the pressure receiving member, and a liquid level difference between the static liquid. A static pressure generating chamber that generates the static pressure; and a static pressure adjusting device that adjusts the static pressure, the static pressure generating chamber and the static pressure working chamber communicate with each other through a communication path, and the static pressure The liquid is contained in the generation chamber, the static pressure working chamber, and the communication path.

  In this case, preferably, the liquid level in the static pressure generating chamber is higher than the liquid level in the static pressure working chamber, and more preferably, the horizontal cross-sectional area of the pressure receiving surface of the pressure receiving member is the static level. It is larger than the horizontal sectional area of the pressure generating chamber.

  In the present invention, the static pressure adjusting device includes a lifter, and the lifter moves the static pressure generation chamber or the static pressure action chamber up and down to change the liquid level of the liquid in the static pressure generation chamber. Alternatively, the static pressure adjusting device may be formed directly in the static pressure generating chamber or the communication path or may be branched from the static pressure generation chamber or the communication path, and the volume A pressing member that presses the variable portion, and the liquid level in the static pressure generating chamber is changed by pressing the volume variable portion with the pressing member to change the volume. good.

  According to the present invention, since the pressure reducing mechanism generates a reverse load by a static pressure generated by a liquid level difference of a stationary liquid, compressed air is compressed by an air cylinder, an air bag, or the like by a pump, a solenoid valve, or the like. Compared to the conventional method of generating a reverse load by supplying to the plate, not only can the consumption of electrical energy be significantly reduced, but the static pressure without irregular pressure fluctuations can be stably applied to the upper platen as a reverse load. As a result, a stable pressing force can be obtained. In addition, the reverse load, that is, the pressing force can be precisely and stably finely adjusted by changing the liquid level difference, so that the workpiece is a semiconductor substrate, a glass substrate, etc. Even an ultra-thin quartz substrate of μm can be reliably polished without being damaged.

It is a longitudinal cross-sectional view which shows 1st Embodiment of the double-side polish apparatus which concerns on this invention, and shows the state which the upper surface plate rose to the non-polishing position. It is a principal part enlarged view which expands and shows the part of the transmission-shaft coupling mechanism of FIG. It is sectional drawing which shows the state which the upper surface plate descend | falls for grinding | polishing from the state of FIG. 1, and has stopped at the origin position before contacting a workpiece | work. FIG. 4 is a cross-sectional view showing a state where the upper surface plate is lowered from the state of FIG. 3 and is in contact with the workpiece and polishing is performed, and shows a case where the pressing force is small. It is sectional drawing when the pressing force of an upper surface plate is larger than FIG. It is a longitudinal cross-sectional view which shows 2nd Embodiment of the double-side polish apparatus which concerns on this invention, and shows the state which the upper surface plate fell to the grinding | polishing position. It is a longitudinal cross-sectional view which shows 3rd Embodiment of the double-side polish apparatus which concerns on this invention, and shows the state which the upper surface plate fell to the grinding | polishing position. It is a longitudinal cross-sectional view which shows 4th Embodiment of the double-side polish apparatus which concerns on this invention, and shows the state which the upper surface plate rose to the non-polishing position. It is a longitudinal cross-sectional view which shows 5th Embodiment of the double-side polish apparatus which concerns on this invention, and shows the state which the upper surface plate fell to the grinding | polishing position.

  1 to 5 show a first embodiment of a double-side polishing apparatus. A double-side polishing apparatus 1A according to the first embodiment includes a machine body 2 and a vertical axis (processing center axis) L inside the machine body 2. Are arranged so as to surround the outer periphery of the lower surface plate 4, the annular upper surface plate 3, the lower surface plate 4, the sun gear 5 disposed at the center of the lower surface plate 4. An internal gear 6 provided, and a plurality of carriers 7 disposed on the lower surface plate 4 and meshing with the sun gear 5 and the internal gear 6 are provided.

  The machine body 2 includes a main body case 2a, a support column 2b rising from the main body case 2a, an upper frame 2c supported by the upper end of the support column 2b, and a cylindrical shaft disposed at the upper center of the main body case 2a. A housing 2d and a gear box 2e disposed below the shaft housing 2d inside the main body case 2a are provided.

  The lower surface plate 4 is fixed to the lower surface plate receiver 10, and a cylindrical lower surface plate shaft 11 is attached to the lower center of the lower surface plate receiver 10, and the lower surface plate shaft 11 is accommodated inside the shaft housing 2 d. The lower surface plate bearing 12 is rotatably supported. A lower surface plate worm gear 13 is attached to the lower end portion of the lower surface plate shaft 11 in the gear box 2e, and the lower surface plate worm gear 13 is driven and rotated by a lower surface plate motor 14 attached to the outside of the gear box 2e. It has become so.

  The sun gear 5 is fixed to a sun gear receiver 17, and a cylindrical sun gear shaft 18 is attached to the lower center of the sun gear receiver 17, and the sun gear shaft 18 is connected to the lower surface plate shaft 11. It is housed concentrically inside and is rotatably supported by a sun gear bearing 19 at the lower end of the gear box 2e. A sun gear worm gear 20 is attached to the sun gear shaft 18, and the sun gear worm gear 20 is driven and rotated by a sun gear motor 21 attached to the outside of the gear box 2e.

  Further, the internal gear 6 is fixed to an internal gear receiver 24, and a cylindrical internal gear shaft 25 is attached to a lower center portion of the internal gear receiver 24, and the internal gear shaft 25 is It arrange | positions so that the outer periphery of the shaft housing 2d may be surrounded, and the lower end part is rotatably supported by the internal gear bearing 26. FIG. An internal gear gear 27 is attached to the internal gear shaft 25, and the internal gear gear 27 is driven and rotated by an internal gear motor 28 attached to the machine body 2.

  On the other hand, as can be seen from FIG. 2, the upper surface plate 3 is fixed to the lower surface of the upper surface plate suspension 31, and a plurality of studs 32 extend upward on the upper surface of the upper surface plate suspension 31. The upper surface plate 3 is supported via the stud 32 so that the upper surface plate 3 can be moved up and down by an upper surface plate elevating mechanism 33 installed on the upper part of the machine body 2 and can be driven and rotated by an upper surface plate rotating mechanism 34. Yes.

  The upper surface plate elevating mechanism 33 includes a servo type elevating cylinder 35 fixed to the upper surface of the upper frame 2c of the machine body 2, an elevating plate 36 fixed to the upper end of the rod 35a of the elevating cylinder 35, and the elevating plate. A cylindrical lifting rod 37 extending downward from 36 is supported in a vertically movable manner inside a rod receiver 38 fixed to the upper surface of the upper frame 2c. The elevating cylinder 35 may be a servo motor. The upper surface plate rotating shaft 39 is fixedly connected to the lifting rod 37 in the direction (vertical direction) along the machining center axis L inside the lifting rod 37, but in the rotational direction, The lift rod 37 is held so as to have a free mutual relationship.

A disc-shaped drive plate 40 is fixed to the lower end of the upper platen rotating shaft 39, and the stud 32 extends from the drive plate 40 in the connecting hole 40 a formed in the drive plate 40. The upper surface plate 3 is driven and rotated through the stud 32 by being fitted so as to be movable up and down while protruding upward.
At the upper end of the stud 32, a flange-like locking portion 32 a is provided. The locking portion 32 a is locked to the upper surface of the drive plate 40 when the upper surface plate 3 is raised and lowered, and the upper surface plate rotating shaft 39. And the upper surface plate 3 are connected to each other so that when the workpiece W is polished, it is spaced upward from the upper surface of the drive plate 40 so that the weight of the upper surface plate 3 is not applied to the upper surface plate rotating shaft 39. .

An upper surface plate gear 41 is fixed to the upper end of the upper surface plate rotation shaft 39, and the upper surface plate gear 41 is connected to an upper surface plate motor 42, and the upper surface plate motor 42 drives the upper surface plate 3. It is designed to be rotated. Therefore, the upper surface plate rotating shaft 39, the upper surface plate gear 41, and the upper surface plate motor 42 constitute the upper surface plate rotating mechanism 34.
The upper surface plate motor 42 is fixed to the elevating plate 36 and moves up and down together with the elevating plate 36 and the upper surface plate rotating shaft 39. Therefore, the upper surface plate rotation shaft 39 constitutes a part of the upper surface plate lifting mechanism 33 and also constitutes a part of the upper surface plate rotation mechanism 34.

  The lower surface plate motor 14, the sun gear motor 21, the internal gear motor 28, and the upper surface plate motor 42 are controlled by a control device (not shown) according to a preset program at a necessary rotational speed in a necessary rotational direction. They are individually driven and rotated.

  When polishing the workpiece W, after the workpiece W is held in the workpiece holding hole of the carrier 7, the upper surface plate 3 is lowered as shown in FIG. The workpiece W is sandwiched between the work surface of the lower surface plate 4 and the upper surface of the lower surface plate 4, and the upper surface plate 3, the lower surface plate 4, the sun gear 5, and the internal gear 6 rotate in this state. Thus, the carrier 7 revolves around the sun gear 5 while rotating, and both surfaces of the work W held by the carrier 7 are polished by the work surfaces of the upper surface plate 3 and the lower surface plate 4. At the time of polishing, polishing slurry is supplied to the working surface from a supply hole formed in the upper surface plate 3.

  In the double-side polishing apparatus 1 </ b> A, a pressure reducing mechanism that applies a load opposite to the load of the upper surface plate 3 (hereinafter referred to as “reverse direction load”) to the upper surface plate 3 when the workpiece W is polished. 44 is provided, and the difference between the load of the upper surface plate 3 and the reverse load of the pressure reducing mechanism 44 is used as the pressing force to the workpiece W.

  The pressure reducing mechanism 44 includes a static pressure transmission shaft 45 disposed so as to be vertically movable at a position where the axis of the upper surface plate 3 coincides with the upper surface plate 3, and the upper surface plate 3 and the static pressure transmission shaft 45 when the workpiece W is polished. A static pressure is generated by the liquid level difference H of the stationary liquid 47 and the transmission shaft coupling mechanism 46 that couples the upper surface plate to the static pressure transmission shaft 45. And a static pressure generating device 48 that acts as a load in the direction opposite to the load of 3.

The static pressure transmission shaft 45 is accommodated in the sun gear shaft 18 such that upper and lower ends extend upward and downward from the sun gear shaft 18 and is supported by a bearing mechanism (not shown). Therefore, the position where the static pressure transmission shaft 45 is disposed is below the upper surface plate 3.
A contact surface 45a at the upper end of the static pressure transmission shaft 45 is formed in a horizontal plane, and comes into contact with the self-aligning bearing 49 that constitutes the transmission shaft coupling mechanism 46 so as to support the load from the upper surface plate 3. ing.

  In the present embodiment, a ball bearing is used as the self-aligning bearing 49. As shown in FIG. 2, this ball bearing houses a spherical body 49a in a hemispherical concave chamber 49b that opens downward, and a large number of small balls 49c between the spherical body 49a and the interior surface of the concave chamber 49b. Is configured such that the sphere 49a can rotate 360 degrees in all directions. The self-aligning bearing 49 is attached to the center bearing mounting portion 31 a of the upper surface plate suspension 31, and the spherical body 49 a contacts the contact surface 45 a at the upper end of the static pressure transmission shaft 45 by raising and lowering the upper surface plate 3. The upper surface plate 3 is connected to or disconnected from the static pressure transmission shaft 45 so as to be rotatable relative to the static pressure transmission shaft 45.

  The static pressure generator 48 is connected to the lower end of the static pressure transmission shaft 45 through a load sensor 52. The static pressure generator 48 includes a plate-shaped pressure receiving member 53 connected to the lower end of the static pressure transmission shaft 45 via the load sensor 52, and a static pressure working chamber for applying the static pressure to the pressure receiving member 53. 54, a static pressure generating chamber 55 that generates the static pressure by the liquid level difference H of the liquid 47 that is stationary, and a static pressure adjusting device 56 that adjusts the static pressure.

  The static pressure working chamber 54 is formed inside a bag 57 made of a liquid-impermeable material that is thin and lightweight, such as synthetic rubber or synthetic resin, and has strength, durability, and flexibility. Is placed on a support base 58, and the pressure receiving member 53 is in contact with the upper surface of the bag 57 so that the pressure receiving surface on the lower surface receives the pressure evenly.

  The static pressure generating chamber 55 is formed inside a hollow member 59 such as a pipe supported in the vertical direction, preferably vertically, on the machine body 2, and the upper portion of the static pressure generating chamber 55 is open to the outside air. The lower part communicates with the lower part of the static pressure working chamber 54 through a communication passage 61 in the flexible tube 60, and the static pressure generating chamber 55, the communication path 61, and the static pressure working chamber 54 are filled with oil. The liquid 47 such as water or water is filled.

  The horizontal cross-sectional shape of the static pressure generation chamber 55 may be any shape such as a circle, an ellipse, a rectangle, a triangle, and other polygons, and the horizontal cross-sectional area of the static pressure generation chamber 55 May be constant in the height direction, such as conical, pyramidal, truncated cone, truncated pyramid, inverted cone, inverted pyramid, inverted truncated cone, inverted truncated pyramid, etc. The height may change regularly or irregularly. On the other hand, the horizontal cross-sectional shape of the static pressure working chamber 54 may be an arbitrary shape such as a circle, a ring, a polygon, or a polygon.

  The static pressure working chamber 54 and the static pressure generating chamber 55 need to be arranged in a positional relationship such that the liquid level in the static pressure generating chamber 55 is higher than the liquid level in the static pressure acting chamber 54. is there. The horizontal cross-sectional area of the pressure-receiving surface of the pressure-receiving member 53, that is, the contact area between the pressure-receiving member 53 and the static pressure working chamber 54 is set larger than the horizontal cross-sectional area of the static pressure generating chamber 55. Static pressure can be reliably generated without taking a particularly large space.

  With this configuration, a static pressure is generated by the liquid level difference H between the liquid 47 in the static pressure generating chamber 55 and the liquid 47 in the static pressure working chamber 54, and this static pressure is applied to the static pressure action. By acting on the pressure receiving member 53 through the liquid 47 in the chamber 54 and pushing the pressure receiving member 53 upward, a reverse load is applied to the upper surface plate 3 via the static pressure transmission shaft 45 when the workpiece W is polished. It is something to be made.

The static pressure adjusting device 56 includes a lifter 64 that moves the support table 58 up and down, and the lift 64 moves the static pressure working chamber 54 up and down to change the volume of the static pressure working chamber 54. The liquid level of the liquid 47 in the static pressure generating chamber 55 is changed.
The lifter 64 elevates and lowers an elevating shaft 65 made of a male screw by rotating it with a lifter motor 67 via a female screw (not shown) and a worm gear provided in the body 66, and the elevating shaft 65 is supported by the support shaft 65. It is connected to the lower surface of the table 58. The lifter motor 67 is controlled by a control device, so that the lift control of the lift shaft 65 is precisely performed. However, the lifter 64 is not limited to such a configuration as long as the lifter 64 can move up and down the static pressure working chamber 54.

Next, an operation when the workpiece W is polished by the double-side polishing apparatus 1A having the above configuration will be described. This operation is automatically performed according to a program previously input to the control device.
FIG. 1 shows a state when the workpiece W is not polished. At this time, the upper surface plate 3 is lifted by the extension of the rod 35a of the elevating cylinder 35 via the elevating plate 36 and the elevating rod 37, the upper surface plate rotating shaft 39, the drive plate 40, the stud 32, and the upper surface plate suspension 31. Occupies the position of the rising edge. Further, since the lifting shaft 65 of the lifter 64 is at the rising end position, the static pressure transmission shaft 45 also occupies the origin position which is the rising end position.

  At this time, the weight of the pressure receiving member 53, the load sensor 52, and the static pressure transmission shaft 45 acts downward on the liquid 47 in the static pressure acting chamber 54 as a load, via the pressure receiving member 53. On the other hand, the static pressure generated by the liquid level difference H of the liquid 47 in the static pressure acting chamber 54 and the static pressure generating chamber 55 acts on the pressure receiving member 53 upward as a reverse load. The reverse loads are balanced with each other.

  Here, the horizontal sectional area of the pressure receiving surface of the pressure receiving member 53 (the contact area between the pressure receiving member 53 and the static pressure acting chamber 54) is A, and the pressure receiving member 53 acts on the liquid 47 in the static pressure acting chamber 54. When the load (the total weight of the static pressure transmission shaft 45, the load sensor 52, and the pressure receiving member 53 in the state of FIG. 1) is F, and the specific gravity of the liquid 47 is G, the relationship F ÷ A = H × G is established.

  From this state, when the workpiece W is set on the carrier 7 placed on the lower surface plate 4 and the start button of the operation panel is pressed, the upper surface plate 3 is It is integrated with the members (hereinafter referred to as “elevation-related members”) from the elevating plate 36 and the elevating rod 37 to the upper surface plate rotating shaft 39, the drive plate 40, the stud 32, and the upper surface plate suspension 31. The spherical body 49a of the self-aligning bearing 49 is temporarily stopped at the first stop position immediately before contacting the contact surface 45a at the upper end of the static pressure transmission shaft 45.

  Next, when the rod 35a of the lifting cylinder 35 is slowly shortened, the upper surface plate 3 is lowered at a low speed from the first stop position while being integrated with the lifting-related member, as shown in FIG. The spherical body 49a of the self-aligning bearing 49 comes into contact with the contact surface 45a of the static pressure transmission shaft 45, and the load of the upper surface plate acts on the static pressure transmission shaft 45. Stop at the second stop position, which is a position that does not contact W. The upper surface plate suspension 31 and the stud 32 also stop at that position. However, since the rod 35a of the elevating cylinder 35 continues to be slightly shortened thereafter, the drive plate 40 is displaced downward with respect to the stud 32, and the engaging portion 32a at the upper end of the stud 32 is located on the upper surface of the drive plate 40. Separate from.

  As a result, the total weight of the upper surface plate 3 including the upper surface plate suspension 31, the stud 32 and the self-aligning bearing 49 (hereinafter referred to as “upper surface plate load”) acts on the drive plate 40. From this state, all act on the static pressure transmission shaft 45 downward. For this reason, the downward load acting on the liquid 47 in the static pressure acting chamber 54 via the pressure receiving member 53 and the bag 57 at the lower end of the static pressure transmission shaft 45 increases, and the static load is generated to generate a reverse load that balances it. The liquid level in the pressure generating chamber 55 rises and the liquid level difference H increases.

  Next, as shown in FIG. 4, when the lifter motor 67 is driven, the lift shaft 65 of the lifter 64 is lowered, and the volume of the bag 57, that is, the volume of the static pressure working chamber 54 is expanded. When the liquid 47 in the static pressure generating chamber 55 flows into the liquid 54, the liquid level difference H decreases, and the reverse load acting upward on the pressure receiving member 53 decreases accordingly. At this time, since the upper surface plate load still acts on the static pressure transmission shaft 45, the upper surface of the bag 57 is displaced downwardly so that the upper surface plate load is balanced with the reduced reverse load. The transmission shaft 45 and the upper surface plate 3 are lowered, and the upper surface plate 3 comes into contact with the upper surface of the workpiece W (landing). During the landing operation, the lowering speed of the elevating shaft 65 is adjusted to adjust the flow rate of the liquid 47 into the static pressure working chamber 54, so that the upper surface plate 3 is attached from the second stop position. The board speed can be set arbitrarily.

  Further, even when the descending speed of the lifting shaft 65 of the lifter 64 is constant, the horizontal sectional area of the static pressure generating chamber 55 formed inside the hollow member 59 is changed in the vertical direction. However, the moving amount (inflow amount / outflow amount) of the liquid 47 due to the raising and lowering of the elevating shaft 65 does not change, but the changing speed of the static pressure increases / decreases as the cross-sectional area for each liquid level gradually decreases / increases. Therefore, the flow rate of the liquid 47 into the static pressure working chamber 54 can be adjusted by using this, whereby the change rate of the static pressure, that is, the reverse load acting on the upper surface plate 3 can be adjusted. It is possible to control the action speed (landing speed / rising speed) stepwise (curved).

  As described above, the carrier 7 rotates as the sun gear 5, the internal gear 6, the upper surface plate 3, and the lower surface plate 4 rotate while the upper surface plate 3 is in contact with the upper surface of the workpiece W. While revolving around the sun gear 5, both surfaces of the work W held by the carrier 7 are polished by the work surfaces of the upper surface plate 3 and the lower surface plate 4. At this time, the pressing force acting on the workpiece W by the upper surface plate 3 is the difference between the upper surface plate load and the reverse load generated by the pressure reducing mechanism 44.

  The pressing force can be arbitrarily changed during polishing by controlling the height of the lift shaft 65 of the lifter 64. That is, when the elevating shaft 65 is lowered, the volume of the static pressure working chamber 54 is expanded and the liquid 47 in the static pressure generating chamber 55 flows into the static pressure working chamber 54 as described above. Since the position difference H decreases and the reverse load acting upward on the pressure receiving member 53 decreases accordingly, the pressing force increases.

On the contrary, when the elevating shaft 65 is raised, the volume of the static pressure working chamber 54 is reduced and the liquid 47 in the static pressure working chamber 54 flows out into the static pressure generating chamber 55. And the reverse load acting upward on the pressure receiving member 53 increases accordingly, and the pressing force decreases. It is also possible to make the pressing force zero by raising the elevating shaft 65.
FIG. 5 shows a state in which a large pressing force is acting on the workpiece W as the elevating shaft 65 is lowered and the reverse load is reduced as compared with FIG. 4.

  The pressing force is obtained from the load of the upper surface plate 3 and the static pressure transmission shaft 45 measured by the load sensor 52, and the measurement signal from the load sensor 52 is set so that the pressing force becomes a set value. Based on the above, the lifter 64 is controlled to rise and fall during polishing. For example, the pressing force can be reduced as the thickness of the workpiece W approaches the target thickness, and can be reduced to zero at the end of polishing.

  Here, since the static pressure transmission shaft 45 is connected to the upper surface plate 3 through a self-aligning bearing 49 in a non-rotating state, the static pressure transmission shaft 45 is less affected by the inclination of the upper surface plate 3. The load sensor 52 is installed below the non-rotating static pressure transmission shaft 45 and is not affected by the inclination of the upper surface plate 3 at all, so that the pressing force can be accurately and accurately determined. Therefore, the control accuracy of the pressing force is improved.

  Further, since the pressure reducing mechanism 44 is a method of generating a reverse load by the static pressure generated by the liquid level difference H of the stationary liquid 47, the compressed air is supplied to an air cylinder, an air bag or the like by a pump or a solenoid valve. Compared to the conventional method that generates reverse load by supplying it, not only the consumption of electrical energy is very small, but also static pressure without irregular pressure fluctuations can act stably on the upper platen as reverse load. As a result, a stable pressing force can be obtained. Moreover, since the reverse load, that is, the pressing force can be precisely and stably finely adjusted by changing the liquid level difference H, of course, when the workpiece W is a semiconductor substrate or a glass substrate, Even an ultra-thin quartz substrate of several tens of μm can be reliably polished without being damaged.

When the polishing is finished, the rotation of the upper surface plate 3, the lower surface plate 4, the sun gear 5, and the internal gear 6 is stopped, and the rod 35a of the elevating cylinder 35 is slowly extended, so that the elevating plate 36 and the elevating rod 37 The upper surface plate rotating shaft 39 and the drive plate 40 are raised at a low speed. When the drive plate 40 is locked to the locking portion 32a of the stud 32 and the upper surface plate 3 is slightly lifted, the rod 35a of the elevating cylinder 35 extends at a high speed from that position, thereby The surface plate 3 is lifted at a high speed and lifted to the position of the rising edge in FIG. At the same time, the pressure reducing mechanism 44 returns to the original position.
Then, the polished workpiece W is taken out from the carrier 7, and another workpiece W is set and new polishing is performed.

  The first embodiment can also be configured as in the following various modifications. That is, in the illustrated example, in the upper surface plate elevating mechanism 33, the elevating cylinder 35 is connected in parallel to the elevating rod 37 via the elevating plate 36. 37 may be connected in series, and the elevating rod 37 and the upper surface plate rotation shaft 39 may be shared by a single shaft.

  The upper surface plate rotating mechanism 34 is configured to drive and rotate the upper surface plate 3 via an upper surface plate rotation shaft 39 by an upper surface plate motor 42 attached to the elevating plate 36. It may be a known rotation mechanism used in the double-side polishing apparatus. That is, a cylindrical driver is rotatably disposed at the center of the lower surface plate 4 so as to surround the static pressure transmission shaft 45, and the driver is connected to the sun gear shaft 18 via a driver shaft extending concentrically. It is connected to an upper surface plate motor mounted at an appropriate position on the machine body, and a hook projecting from the inner periphery of the upper surface plate 3 toward the center of rotation is engaged with a locking groove on the outer periphery of the driver. Alternatively, a rotating mechanism that rotates the upper surface plate 3 may be used. In this case, the elevating plate 36, elevating rod 37, upper surface plate rotating shaft 39, upper surface plate gear 41, upper surface plate motor 42 on the elevating plate 36, etc. are omitted, and the elevating cylinder 35 faces the rod 35a downward. The upper surface plate 3 is tiltably and rotatably connected to the lower end of the rod 35a.

  Further, the self-aligning bearing 49 constituting the transmission shaft coupling mechanism 46 is formed of a ball bearing having a spherical body 49a in contact with the static pressure transmission shaft 45 as a center. The present invention is not limited to such a configuration, and may be a self-aligning ball bearing in which a ball is interposed between an inner ring and an outer ring, or a self-aligning roller bearing in which a roller is interposed between an inner ring and an outer ring. Alternatively, a gyro-type bearing may be used. When such a ball bearing, roller bearing, or gyro-type bearing is used as the self-aligning bearing, the outer ring is attached to the upper surface plate 3 side, and a contact surface for the static pressure transmission shaft 45 is formed on the inner ring. The contact surface on the inner ring side can be formed by attaching a member such as a plate to the lower surface of the inner ring so as to close the hollow portion of the inner ring. The contact surface 45a of the static pressure transmission shaft 45 that contacts the contact surface of the inner ring can be formed in a horizontal plane or a spherical surface.

  Further, the static pressure generating chamber 55 in the static pressure generating device 48 may be sealed without the upper end being opened to the outside air. In that case, like the static pressure working chamber 54, the static pressure generating chamber 55 is thin and lightweight, such as synthetic rubber or synthetic resin, and is liquid impervious having strength, durability and flexibility. It is necessary to enclose only the liquid 47 so that no gas is mixed therein. This is because when the gas is mixed, the compression rate of the gas is larger than that of the liquid, and the static pressure is absorbed by the compression of the gas.

  FIG. 6 shows a second embodiment of the double-side polishing apparatus according to the present invention. The double-side polishing apparatus 1B of the second embodiment is different from the double-side polishing apparatus 1A of the first embodiment in that the static pressure adjusting device 56 raises and lowers the static pressure generating chamber 55 with a lifter 64. The liquid level in the chamber 55 is changed.

That is, the lifter 64 includes a pulling member 70 made of a wire, a chain, or the like, and a winding member 71 such as a pulley or a gear that is rotatably supported by the machine body 2 and around which the pulling member 70 is wound. The leading end of the pulling member 70 is connected to the upper end of a hollow member 59 forming a static pressure generating chamber 55, and the winding member 71 is driven and rotated by a driving means (not shown). Then, the winding member 71 is rotated in the forward and reverse directions to wind up or pull out the pulling member 70 to raise and lower the static pressure generating chamber 55, thereby liquid of the liquid 47 in the static pressure generating chamber 55. The static pressure in the static pressure working chamber 54 increases or decreases as the position increases or decreases.
The bag 57 forming the static pressure working chamber 54 is placed on a support base 72 fixed to the machine body 2.

  However, the lifter 64 in the second embodiment is not limited to such a configuration as long as it can raise and lower the static pressure generating chamber 55.

  Since the other configurations, operations, modifications, and the like of the second embodiment are substantially the same as those of the first embodiment, the same reference numerals as those of the first embodiment are attached to the main identical components. The description is omitted.

  FIG. 7 shows a third embodiment of the double-side polishing apparatus according to the present invention. The difference between the double-side polishing apparatus 1C of the third embodiment and the double-side polishing apparatus 1A of the first embodiment is that the static pressure adjusting device 56 connects the static pressure generating chamber 55 and the static pressure working chamber 54. The liquid level in the static pressure generating chamber 55 is changed by changing the cross-sectional area.

Therefore, in the third embodiment, a part of the tube 60 forming the communication passage 61 is formed with a volume variable part 62 whose volume is changed by being elastically deformed by pressing, and a pair of volumes is formed on both sides of the volume variable part 62. The first pressing member 73a is fixed to the machine body 2, and the other second pressing member 73b is connected to the pressing device 74. Then, the second pressing member 73b is advanced by the pressing device 74 to press the volume variable portion 62 and deformed to reduce the cross-sectional area, that is, the volume, thereby reducing the liquid in the static pressure generating chamber 55. As the position rises, the static pressure in the static pressure working chamber 54 increases.
The bag 57 forming the static pressure working chamber 54 is placed on a support base 72 fixed to the machine body 2.

  In the third embodiment, the volume variable section 62 is formed directly on the tube 60 forming the communication path 61, but the volume variable section 62 is located at a place other than the tube 60 in the static pressure working chamber. It can also be formed so as to press areas other than 54. For example, the volume variable portion 62 may be directly formed in a portion of the hollow member 59 forming the static pressure generating chamber 55 where the liquid 47 is accommodated, or a hollow body (see FIG. 9 (see “Hollow body 77”) can be branched so as to communicate with the static pressure generating chamber 55 or the communication passage 61, and the volume variable portion 62 can be formed in the hollow body.

  Since the configuration, operation, modification, and the like of the third embodiment other than those described above are substantially the same as those in the first embodiment, the same reference numerals as those in the first embodiment are attached to the main identical components. The description is omitted.

  FIG. 8 shows a fourth embodiment of the double-side polishing apparatus according to the present invention. The double-side polishing apparatus 1D of the fourth embodiment is different from the double-side polishing apparatus 1A of the first embodiment in that the static pressure working chamber 54 is formed inside the casing 76, and the pressure receiving member 53 is formed of a piston. Is a point.

  That is, the pressure receiving member, that is, the piston 53 is accommodated in the casing 76 so as to be slidable in the vertical direction via a seal member (not shown), and the lower surface of the piston 53 and the inner bottom and inner surfaces of the casing 76 are accommodated. The static pressure working chamber 54 is defined and formed between the side surfaces. The lift shaft 65 of the lifter 64 is connected to the center position of the outer bottom surface of the casing 76.

Since the configuration, operation, modification, and the like of the fourth embodiment other than those described above are substantially the same as those in the first embodiment, the same reference numerals as those in the first embodiment are attached to the main same components. The description is omitted.

  FIG. 9 shows a fifth embodiment of the double-side polishing apparatus according to the present invention. The main difference between the double-side polishing apparatus 1E of the fifth embodiment and the double-side polishing apparatus 1C of the third embodiment shown in FIG. 7 is that the static pressure working chamber 54 of the static pressure generator 48 that constitutes the decompression mechanism 44. And the pressure receiving member 53 is installed at a position above the upper surface plate 3 of the machine body 2, and the upper surface plate rotation shaft 39 also serves as the static pressure transmission shaft 45. The static pressure from the static pressure generator 48 is transmitted to the surface plate 3. Accordingly, the static pressure transmission shaft 45 is also disposed above the upper surface plate 3.

  The difference between the fifth embodiment and the third embodiment will be briefly described below. An annular bag 57 is placed on the upper frame 2 c of the machine body 2, the static pressure working chamber 54 is formed inside the bag 57, and the pressure receiving member having an annular shape is formed on the bag 57. A member 53 is placed, a lifting cylinder 35 is mounted on the pressure receiving member 53, and a rod 35 a of the lifting cylinder 35 is connected to the lifting plate 36 via a load sensor 52.

  The upper platen rotating shaft 39, that is, the static pressure transmission shaft 45 penetrates the center of the pressure receiving member 53 and the bag 57 in a loosely inserted state, and penetrates the center of the drive plate 40 while being fixed to the drive plate 40. The lower end is connected to the upper surface plate 3 via an automatic alignment bearing 49 so as to be tiltable in all directions of 360 degrees. The drive plate 40 and the stud 32 have a degree of freedom in the direction in which the axis is inclined, but are connected so as to be fixed in the rotational direction.

  The static pressure working chamber 54 communicates with the static pressure generating chamber 55 through the communication passage 61, and a hollow body 77 such as a pipe is connected to the lower end of the static pressure generating chamber 55 in a branched state. A volume variable portion 62 whose volume can be changed is formed, and a pair of pressing members 73a and 73b for pressing the volume variable portion 62 from both sides, and a pressing device 74 for pressing one pressing member 73b are provided. ing.

In the fifth embodiment, the upper platen 3 is lifted and lowered by the lifting cylinder 35 on the pressure receiving member 53 via the lifting plate 36, the lifting rod 37 and the static pressure transmission shaft 45. The upper surface plate motor 42 is driven to rotate through the static pressure transmission shaft 45 by the attached upper surface plate motor 42.
Then, after polishing the work W, the upper surface plate 3 is lowered by the elevating cylinder 35 to a position immediately before contacting the work W via the static pressure transmission shaft 45, and then the air circuit of the elevating cylinder 35 The workpiece W is brought into contact with the workpiece W by the action of static pressure by being released, and the workpiece W is processed by being driven and rotated via the static pressure transmission shaft 45. Adjustment of the pressing force by the upper surface plate 3 during polishing is performed in the same manner as in the third embodiment by operating the pressing device 74.

  Since the configuration, operation, modification, and the like of the fifth embodiment other than those described above are substantially the same as those of the third embodiment, the same reference numerals as those of the third embodiment are assigned to the main identical components. The description is omitted.

1A, 1B, 1C, 1D, 1E Double-side polishing device 3 Upper surface plate 4 Lower surface plate 33 Upper surface plate lifting mechanism 44 Depressurization mechanism 45 Static pressure transmission shaft 47 Liquid 48 Static pressure generator 49 Automatic centering bearing 53 Pressure receiving member 54 Static Pressure working chamber 55 Static pressure generating chamber 56 Static pressure adjusting device 61 Communication path 62 Volume variable portion 64 Lifter 73a, 73b Press member W Work H Liquid level difference L Axis line

Claims (6)

An upper surface plate and a lower surface plate that can be driven and rotated while sandwiching a workpiece, an upper surface plate elevating mechanism that raises and lowers the upper surface plate, and a load opposite to the load of the upper surface plate when polishing the workpiece. In a double-side polishing apparatus having a pressure reducing mechanism that acts on a surface plate, wherein the difference between the load of the upper surface plate and the load by the pressure reducing mechanism is a pressing force at the time of polishing,
The pressure reducing mechanism includes a static pressure transmission shaft arranged to move up and down at a position where the axis line coincides with the upper surface plate, and an automatic centering bearing that interconnects the upper surface plate and the static pressure transmission shaft. A static pressure generating device that generates a static pressure due to a liquid level difference of a stationary liquid, and that acts on the static pressure transmission shaft as a load opposite to a load by the upper surface plate,
A double-side polishing apparatus characterized by that.   The static pressure generator includes a pressure receiving member connected to the static pressure transmission shaft, a volume variable static pressure working chamber that applies a static pressure to the pressure receiving member, and a static pressure generated by a liquid level difference between the static liquids. A static pressure generating chamber for generating the static pressure, and a static pressure adjusting device for adjusting the static pressure. The static pressure generating chamber and the static pressure working chamber communicate with each other through a communication path, and the static pressure generating chamber and the static pressure generating chamber The double-side polishing apparatus according to claim 1, wherein the liquid is contained in the pressure action chamber and the communication path.   The double-side polishing apparatus according to claim 2, wherein the liquid level in the static pressure generating chamber is higher than the liquid level in the static pressure working chamber.   4. The double-side polishing apparatus according to claim 3, wherein a horizontal sectional area of the pressure receiving surface of the pressure receiving member is larger than a horizontal sectional area of the static pressure generating chamber.   5. The static pressure adjusting device includes a lifter, and the lifter moves the static pressure generation chamber or the static pressure action chamber up and down to change the liquid level of the static pressure generation chamber. The double-side polishing apparatus according to any one of the above.   The static pressure adjusting device is configured to press a volume variable portion that is directly formed in the static pressure generating chamber or the communication path or is formed so as to branch from the static pressure generation chamber or the communication path. The pressure level of the liquid in the static pressure generating chamber is changed by pressing the volume variable portion with the pressing member to change the volume. The double-side polishing apparatus according to claim 1.

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