JPH11291164A - Simultaneous double-side grinding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simultaneous double-side grinding device which can ensure high flatness of a processed workpiece, by arranging the respective rotating shafts of two grinding surface plates different from each other. SOLUTION: A rotating shaft of a first grinding surface plate 2 and that of a second grinding surface plate 3 are disposed horizontally to the mounting surface of the simultaneous double-side grinding apparatus and parallel to each other, however, at different locations. A carrier 4 retaining a workpiece 1 is provided so that the rotating shaft 5 of the disc-shaped workpiece held at the superimposed part of the second grinding surface plate 3 on the first grinding surface plate 2 may be arranged in parallel to the rotating shafts of the first and second grinding surface plates and at the middle position between both the rotating shafts. A mechanism is provided which is capable of rotating the first grinding surface plate 2, the second grinding surface plate 3, and the workpiece 1 in the same direction. Static pressure retaining members constituted of a pair of static pressure pads 21a, 21b are arranged, facing the outer sides of both grinding surface plates so as to sandwich the superimposed part of the first grinding surface plate 3 and the second grinding surface plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for simultaneously and accurately polishing both surfaces of a disk-shaped workpiece made of a highly brittle material represented by a semiconductor wafer used for an IC substrate or the like. It relates to a double-sided simultaneous polishing device.

[0002]

2. Description of the Related Art In polishing a disk-shaped workpiece made of a highly brittle material, for example, a semiconductor wafer used for an IC substrate or the like, conventionally, the workpiece is held on a jig by bonding or the like. A method of polishing one side at a time, or a method of simultaneous polishing on both sides, which can save the labor of bonding, is performed. Of these methods, the simultaneous polishing method on both sides is described in, for example,
No. 08, No. 08, No. 08, No. 08, No. 08, No. 08, No. 08, No. 08, No. 08, No. 08 Free upper and lower stool, sun gear,
There is a double-sided simultaneous polishing apparatus provided with an internal gear and a drive shaft for driving and rotating the upper and lower platens. Such a double-sided simultaneous polishing apparatus is capable of simultaneously polishing a plurality of workpieces having different initial thicknesses and efficiently polishing the workpieces to a uniform plate thickness, and extremely easily increasing the parallelism of each workpiece. It is excellent in that it can be finished.

However, there is the following problem in the double-sided simultaneous polishing apparatus using a carrier with gears, as typified by JP-A-8-174408. In other words, when attempting to grind an extremely thin workpiece or one having a large grinding resistance, the strength of the carrier gear cannot withstand the required torque transmission, and the carrier gear, sun gear, and internal gear are driven through abrasive grains. Because the gears are engaged and cause considerable wear on these gear surfaces, the slurry attached to the gears cannot be easily cleaned, so when polishing a very high quality mirror surface, the adverse effects of the slurry remaining on the gears There is a problem that it is easy to receive. In addition, this product has a problem in that, when attempting to automate the attachment and detachment of a workpiece with a large surface plate type with high productivity, the stroke of the attachment / detachment operation of the workpiece becomes large and the path becomes complicated. There is also.

In order to solve the above-mentioned problem in the double-sided simultaneous polishing apparatus using a geared carrier, Japanese Patent Laid-Open Publication No. Hei 3-117560 discloses a method of rotating two polishing plates installed in parallel with each other. The workpieces held by a roller-like carrier are arranged so that the axes of rotation are different, and the axis of rotation of the workpiece is positioned at the midpoint on the straight line connecting the axes of rotation of the two polishing plates. Then, all three members were rotated in the same direction. It is stated that such a configuration has the following effects. That is, the force acting from the workpiece is small for the roller-shaped carrier, so that an extremely thin carrier can be used.The point that the roller-shaped carrier has a simple shape can be easily cleaned, Therefore, it is said that there is an advantage that it can be applied to a high-quality mirror polishing that requires cleanliness in a polishing region.

[0005]

However, Japanese Patent Application Laid-Open No.
The double-sided simultaneous polishing apparatus disclosed in JP-A-117560 has the following problems. In other words, during the processing, a pressing force is applied in a direction in which each of the two polishing plates comes close to each other.
Since the rotating axes of the two polishing plates are different from each other, during the processing, the two
The force shown in FIG. See Figure 2 for details.
At the time of processing, when a pressing force is applied in the direction of bringing both the platens closer to the rotation shaft 34 of the lower platen 32 and the rotation shaft 35 of the upper platen 33, the rotation shafts 34, Forces f ₁ and f ₂ act in directions that are no longer perpendicular to 35. As a result, polishing plates 32, 33
, The degree of parallelism becomes worse, and the processed workpiece 31 has a tendency to be convex at the center and has a tendency to be convex, resulting in a decrease in flatness.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has been developed in a double-sided simultaneous polishing apparatus in which the rotation axes of two polishing plates are differently arranged. It is an object of the present invention to provide a double-sided simultaneous polishing apparatus in which a high flatness is ensured for a workpiece.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a disk-shaped workpiece is placed on a superimposed portion of two opposed flat surface polishing plates. In the double-sided simultaneous polishing machine that is polished with
The rotation axis of the polishing platen and the rotation axis of the second polishing platen are horizontal and parallel to each other with respect to the installation surface of the double-sided simultaneous polishing apparatus, and are at different positions. The rotation axis of the disk-shaped workpiece sandwiched between the overlapping portions with the polishing platen is arranged in parallel with the rotation axes of the first and second polishing platens and at an intermediate position between the two rotation shafts. In this manner, a carrier for holding the workpiece is arranged, and a mechanism for rotating the first polishing plate, the second polishing plate, and the workpiece together in the same direction is provided. A static pressure holding member composed of a pair of static pressure pads is disposed opposite to the outside of both polishing platens so as to sandwich a superimposed portion of the polishing platen and the second polishing platen. A double-sided simultaneous polishing machine was provided.

According to the first aspect of the present invention, the respective rotating shafts of both the polishing platen and the workpiece are installed horizontally with respect to the installation surface of the double-side simultaneous polishing apparatus, that is, perpendicularly to the direction of the attraction, Since a static pressure holding member consisting of a pair of static pressure pads is arranged facing the outside of the two polishing plates so as to sandwich the overlapped portion of the two polishing plates, the rotation of each of the two polishing plates is The forces f ₁ and f ₂ shown in FIG. 2 caused by disposing the shafts differently are canceled out by the external force exerted on the two polishing plates by the static pressure holding member. As a result, during machining, Even if a pressing force is applied in the direction in which both polishing platens approach each other, the platen surfaces of both polishing platens will always be kept parallel to each other in the direction of the attractive force, so High flatness is ensured for the workpiece .

According to a second aspect of the present invention, in the first aspect of the present invention, a static pressure pocket is provided on a surface of the static pressure pad facing the polishing platen, and a static pressure medium as a static pressure medium is provided inside the static pressure pocket. An outlet for the pressurized fluid is provided. Air (gas) may be used as the static pressure medium used for the static pressure holding member. However, considering the cooling efficiency of the processing portion, liquid is better than air, and among liquids, it is widely used in general machine tools. Some industrial coolants are preferred. Therefore, according to the configuration of the second aspect, the respective rotating shafts are arranged differently on the two polishing platens due to the pressure of the static pressure fluid discharged from the static pressure pocket provided in each static pressure pad. As a result, the force opposing the force generated by the above-described operation acts stably, and the discharged static pressure fluid also efficiently contributes to the cooling of the processing portion.

[0010] In the invention according to claim 3, in the invention according to claim 1 or 2, the distance between the rotation axis of the first polishing plate and the rotation axis of the second polishing plate is arbitrarily set. A mechanism was provided. Since there is a principle that the polishing efficiency is proportional to the product of the rotation speed of the polishing platen and the distance between the rotation axis of the polishing platen and the workpiece, the structure according to claim 3 has a constant rotation speed. Even under the conditions, the polishing efficiency can be controlled by changing the distance between the axes.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, any one or two of the first polishing platen, the second polishing platen, and the carrier are selected. A mechanism for giving a forced rotation drive to the motor is provided, and the remaining two or one are provided with a mechanism that is freely held around a predetermined rotation axis. The relative relationship between the first polishing platen, the second polishing platen, and the workpiece held by the carrier during processing with such a configuration will be described. For example, only the first polishing platen is forcibly rotated. When a mechanism for giving a drive is provided, when the first polishing plate rotates, the workpiece is rotated by the friction torque.
If a uniform pressing force acts on the entire surface of the workpiece and the frictional force is also uniform, the workpiece is rotated in the same direction as the first polishing plate at the same rotation speed, and further, the rotation of the workpiece is performed. As a result, the second polishing plate also rotates in the same direction at a constant rotation speed. In this case, the first polishing platen and the workpiece have the same relative speed in size and direction over the entire surface, while the relative speed between the workpiece and the second polishing platen is The size is the same as the relative speed but in the opposite direction, so that the workpiece is polished on both surfaces with uniform polishing efficiency over the entire surface.

According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, a mechanism for forcibly driving each of the first polishing platen, the second polishing platen, and the carrier at the same rotational speed. Was prepared. When the polished portion of the workpiece is symmetrical with respect to the rotation axis of the workpiece, there is no problem with the invention according to the above-mentioned claim 4, that is, the mechanism that rotates the axis other than the axis to which the forced rotation drive is given, although there is no problem. If it is asymmetric, the rotational speed becomes uneven due to the uneven frictional force, and as a result, a state where good machining is not performed may occur. Therefore, if all three members are forcibly driven as in the configuration according to claim 5, the rotation speed does not become uneven even when the polished portion of the workpiece is asymmetric. Further, in this case, if a polishing plate or a bearing that supports a rotating shaft of a workpiece has rotational resistance, the rotational resistance can be canceled to provide a stable constant rotation. Therefore, better processing is performed on the workpiece.

According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, a swing parallel to the polishing surface is applied to one of the two polishing plates or the carrier. A rotating shaft swing mechanism is provided. With such a configuration, each of the two polishing surface plates swings with respect to the workpiece, so that each of the two polishing surface plates and the workpiece press-contact while sequentially changing the contact phase. Therefore, even if the state of the polished surface of a part of the polishing surface plate is slightly deteriorated due to, for example, the adhesion of the slurry or the like, the effect does not appear at a specific portion of the workpiece, and A decrease in processing accuracy can be kept low.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a mechanism diagram showing a main part of a simultaneous double-side polishing apparatus according to the present invention, wherein FIG. 1 (a) is a cross-sectional view, and FIG. 1 (b) is a view of FIG. FIG. 3 is a structural view of the static pressure pad 21b.

Reference numeral 1 denotes a disk-shaped wafer as a workpiece;
Denotes a left surface plate as a first polishing surface plate, 3 denotes a right surface plate as a second polishing surface plate, and 4 denotes a carrier holding the wafer 1. A polishing cloth 8 is mounted on a surface of each of the left surface plate 2 and the right surface plate 3 facing the wafer 1. The carrier 4 is formed of an annular member having a holding hole for the wafer 1, and its outer periphery is supported by several guide rollers (not shown) fixed to rotate freely.
Maintaining rotation is allowed. The rotation axis 5 is the same as the rotation axis of the wafer 1. The left surface plate 2 is supported in the radial direction and the thrust direction, and is rotatably driven at a predetermined rotational speed in the rotational direction 11 by connecting the rotary shaft 6 to a rotary drive source (not shown). On the other hand, the right surface plate 3 is radially supported so as to maintain at least the rotation axis, and presses the wafer 1 against the left surface plate 2 with a predetermined pressure by appropriate means. In addition, right surface plate 3
Is free to rotate around its rotation axis 7. In addition,
Although not shown, it is a matter of course that a mechanism for supplying slurry between the wafer 1 and the left surface plate 2 and between the wafer 1 and the right surface plate 3 is provided.

The rotation axis 6 of the left stool and the rotation axis 7 of the right stool are arranged parallel to each other at a predetermined interval. The distance between the two axes, that is, the distance between the axes, is set to be larger than the diameter of the disc-shaped wafer 1. Then, the position of the carrier 4 for holding the wafer 1 is set such that the rotation shaft 5 of the wafer 1 is located at an intermediate position between the two axes. By the way, as described above, the respective rotating shafts 6 and 7 of the both stools are different from each other, that is, because the rotating shafts are arranged at a distance between the shafts,
During processing, the forces f ₁ and f ₂ as shown in FIG. 2 act on both the platens 2, 3, so that the flatness of the processed workpiece is reduced as it is.

To cope with this, as shown in FIG. 1 (a), a pair of opposite surfaces of the two turntables 2 and 3 are opposed to each other so as to sandwich a superposed portion of the left turntable 2 and the right turntable 3 therebetween. Static pressure pad 21
The static pressure holding member consisting of a and 21b is arranged. As shown in FIG. 3, the polishing platen 3 of the static pressure pad 21b
Is provided with a static pressure pocket 22b on the surface facing the water pipe 23b.
Is provided with a discharge port for the static pressure fluid connected to the discharge port. The same applies to the static pressure pad 21a. As the static pressure fluid, an industrial coolant is used in consideration of the cooling effect. At least during processing, each of the static pressure pads 21a and 21b is disposed so as to have a slight gap with respect to each of the polishing platens 2 and 3 opposed thereto, and from the discharge port in the static pressure pocket so as to fill this gap. If the coolant is released at a predetermined pressure, the force generated by arranging the rotating shafts 6 and 7 of the two stools 2 and 3 differently will cause the static pressure holding member to have the static pressure holding member 2 , 3 are stably canceled by the external force acting on the plates 2, 3
The platen surface is always kept in the same direction as the direction of the attractive force and in parallel with each other, so that a high flatness of the processed wafer 1 is ensured. In addition, the discharged coolant also contributes to cooling of the processing part.

The static pressure holding member will be described in more detail.
Since the purpose of the static pressure holding member is to always keep the surface of the surface plates 2 and 3 parallel to each other, it is necessary to consider the balance in the arrangement and the discharge of the static pressure fluid. That is, the left static pressure pad 21a and the right static pressure pad 21b must be arranged symmetrically with respect to the wafer 1, and the discharge of the static pressure fluid (for example, discharge amount and discharge pressure) must be the same. The left static pressure pad 21a and the right static pressure pad 21b
Are the wafer 1, the left surface plate 2, and the left surface plate 2 shown in FIG.
It is necessary to arrange them symmetrically with respect to a straight line 14 connecting the respective rotary shafts 5, 6, 7 of the right surface plate 3 and the same point when a plurality of static pressure pads are provided. Due to the above points, in the simultaneous double-side polishing machine, when the rotation axes of both stools are perpendicular to the installation surface, due to the effect of gravity, each of the lower static pressure pad and the upper static pressure pad The pressure balance exerted on the platens becomes different, and the platen surfaces of both platens cannot always be kept parallel to each other. Therefore, in the present invention, the rotating shafts 6 and 7 of both stools are arranged horizontally with respect to the installation surface of the double-sided simultaneous polishing apparatus. Thereby, imbalance due to the influence of gravity can be eliminated.

Next, the processing operation in the above configuration will be described. When the left platen 2 is rotated in the direction of arrow 11 by a rotation drive source (not shown), the friction torque causes the wafer 1 to rotate in the direction of arrow 10. When the frictional force is uniform, for example, when the polished portion of the wafer 1 is symmetrical with respect to the rotation axis 5 of the wafer, if the uniform pressing force acts on the entire surface, the wafer 1 is rotated at the same rotation speed as the left platen 2. The rotation of the wafer 1 causes the right platen 3 to rotate in the same direction (the direction of the arrow 12) at a constant rotation speed. As a result, the relative speed between the wafer 1 and the left platen 2 and the relative speed between the wafer 1 and the right platen 3 are opposite in direction but equal in size over the entire surface. The entire surface is polished with the same polishing efficiency.

On the other hand, the wafer 1
When the polished portion is asymmetric, the wafer 1 and the left surface plate 2
Is not equal to the relative speed between the wafer 1 and the right platen 3, so in this case, the forcible drive is also performed on the rotation axes other than the rotation shaft 6 of the left platen. Specifically, when the polished portion of the surface of the wafer 1 facing the left surface plate 2 is asymmetric, while the polished portion of the surface of the wafer 1 facing the right surface plate 3 is symmetric, the left surface In addition to the rotating shaft 6 of the board, the carrier holding at least the wafer 1 is also forcibly driven in the same direction and at the same rotating speed as the rotating shaft 6 of the left surface plate. If the polished portions are asymmetric on both surfaces of the wafer 1, the carrier holding the wafer 1 and the rotating shaft 7 of the right platen in addition to the rotating shaft 6 of the left platen. The forced drive is performed in the same direction and at the same rotational speed as the above. Note that the forced driving of the carrier may be performed by forcibly driving at least one or more of several guide rollers (not shown) fixed on the outer periphery of the carrier so as to rotate freely.

Incidentally, depending on the workpiece, it may be desired to control the polishing efficiency during processing. The polishing efficiency depends on the pressure and the type of polishing liquid, as well as the rotation speed of the platen. Here, if the rotation drive source (not shown) for forcibly driving the rotation shaft 6 of the left surface plate or the like can easily control the rotation speed, for example, an AC spindle motor, the polishing efficiency can be easily controlled. it can. However, if the rotational drive source cannot easily control the rotational speed as in a general-purpose motor, another means must be taken. As described above, the polishing efficiency is proportional to the product of the rotation speed of the surface plate and the distance between the rotation axes of the surface plate and the wafer. Distance 1 between rotating shaft 7 of right surface plate and shaft 1
By changing the value 3, the polishing efficiency can be controlled. Therefore, a mechanism for arbitrarily setting the center distance 13 even during machining is provided. More specifically, a mechanism that can arbitrarily set the distance between the rotation axis 6 of the right surface plate and the rotation axis 6 of the left surface plate, and in conjunction with this mechanism, the rotation shaft 5 of the wafer 1 A mechanism that can be set at an intermediate position between 6 and 7 is provided. These inter-axis changing mechanisms are, for example,
It can be easily realized by a positioning mechanism combining a servo motor and a ball screw.

Further, in the simultaneous double-side polishing apparatus having the structure of the present invention, the contact between the wafer 1 and both the platens 2 and 3
At a constant rotation speed, it is in contact with the same phase every one rotation, and the surface state seen at the average of one rotation of the surface plate, for example, the state of a part of the polishing surface of the surface plate slightly In the case of deterioration, the influence may be transferred to the processed wafer. In order to cope with this, one of the two surface plates 6 and 7 or one of the carriers 4 is provided with a rotating shaft swinging mechanism (not shown) for swinging parallel to the polishing surface. Specifically, the carrier 4 is swung by the rotation shaft swinging mechanism, so that the wafer 1 held by the carrier 4 is swung.
As a result, the contact phases of the wafer 1 and the left platen 2 and the contact phases of the wafer 1 and the right platen 3 slightly change every rotation.
There is no danger that a part of the polished surface of the surface plate will be transferred to the processed wafer. Since the wafer 1 and both the platens 2 and 3 need only be relatively rocked, the rocking by the rotating shaft rocking mechanism is performed not on the carrier 4 but on one of the platens 2 and 3. You may give to one side.

The embodiment of the present invention has been described above. In the above embodiment, the coolant was used as the static pressure fluid discharged from the static pressure holding member.
If it is possible to effectively cancel the force generated by arranging the rotation axes of the two polishing plates differently, a static pressure fluid other than the coolant and also air (gas) can be used. A static pressure medium may be used. Further, instead of using a non-contact type holding member as in the static pressure holding member of the above embodiment, a contact type holding member having a plurality of rollers disposed on a surface facing the polishing platen is used. Can be easily developed from the technique of the present invention.

[0024]

According to the first aspect of the present invention, simultaneous double-side polishing is performed such that a disk-shaped workpiece is sandwiched between superimposed portions of two planar polishing plates provided opposite to each other. In the apparatus, the respective rotating shafts of both the polishing table and the workpiece are set horizontally, that is, perpendicular to the direction of the attractive force with respect to the installation surface of the double-side simultaneous polishing apparatus, so as to sandwich the overlapped portion of the both polishing tables. Since the static pressure holding member consisting of a pair of static pressure pads is arranged facing the outside of both polishing plates, the two polishing plates are arranged with different rotation axes. The resulting force is counteracted by the external force exerted by the static pressure holding member on the two polishing plates, so that the platen surfaces of the two polishing plates are always kept parallel to each other in the direction of the attractive force. High flatness of the processed workpiece It was to be ensured.

According to a second aspect of the present invention, in the first aspect of the present invention, a static pressure pocket is provided on a surface of the static pressure pad facing the polishing platen, and a discharge port of the static pressure fluid is provided inside the static pressure pocket. Was provided. Therefore, due to the pressure of the hydrostatic fluid discharged from the hydrostatic pocket provided in each hydrostatic pad, a force opposing the force generated by arranging the respective rotating shafts on both polishing platens differently. Worked stably, and the discharged static pressure fluid also contributed to the cooling of the processing part.

In the invention according to claim 3, in the invention according to claim 1 or 2, the distance between the rotation axis of the first polishing plate and the rotation axis of the second polishing plate is arbitrarily set. Since a mechanism was provided, it was possible to control the polishing efficiency by changing the distance between the shafts even under the condition that the rotational speed was constant.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, any one or two of the first polishing plate, the second polishing plate and the carrier are selected. A mechanism for giving a forced rotation drive to the motor is provided, and the remaining two or one are provided with a mechanism that is freely held around a predetermined rotation axis. Therefore, if the polished portion of the workpiece is symmetrical with respect to the rotation axis of the workpiece, all three will rotate at the same rotational speed. The object was polished on both sides with uniform polishing efficiency over the entire surface.

According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, a mechanism for forcibly driving each of the first polishing platen, the second polishing platen, and the carrier at the same rotational speed. Was prepared. Therefore, even when the polished portion of the workpiece is asymmetric with respect to the rotation axis of the workpiece, the rotation speed does not become uneven due to the forced driving of all three members. In addition, even in the case where there is rotational resistance in a polishing platen or a bearing that supports a rotating shaft of a workpiece, this can be canceled and a stable constant rotation can be given.

In the invention according to claim 6, in the invention according to any one of claims 1 to 5, a swing parallel to the polishing surface is applied to one of the two polishing plates or one of the carriers. A rotating shaft swing mechanism is provided. For this reason, each of the two polishing surface plates swings with respect to the workpiece, so that each of the two polishing surface plates and the workpiece come into pressure contact while sequentially changing the contact phase. Even when the condition of a part of the polishing surface of the polishing surface is slightly deteriorated, the effect does not appear at a specific part of the workpiece, and the reduction in overall processing accuracy can be kept low. It became.

[Brief description of the drawings]

FIG. 1 is a mechanism diagram showing a main part of a double-sided simultaneous polishing apparatus according to an embodiment of the present invention, and FIG.
(B) is a view as viewed in the direction of arrow A in (a).

FIG. 2 is a conceptual diagram showing the force acting on the two polishing plates during processing, which is unique to the configuration in which the respective rotation axes of the two polishing plates are different from each other.

FIG. 3 shows a static pressure pad 21b according to an embodiment of the present invention.
FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Workpiece (wafer) 2 1st grinding surface plate (left surface plate) 3 2nd grinding surface plate (right surface plate) 4 Carrier 5 Rotation axis of workpiece (wafer) 1 6 1st grinding surface Rotation axis of plate (left platen) 2 7 Rotation axis of second polishing platen (right platen) 3 8 Polishing cloth 10 Rotation direction of workpiece (wafer) 1 11 First polishing platen (left platen) Rotation direction of the plate 2) 12 Rotation direction of the second polishing platen (right platen) 3 13 Interaxial distance between the rotating shafts 6 and 7 of both polishing platens 21a Left static pressure pad (static pressure holding member) 21b) Right static pressure pad (static pressure holding member)

Claims (6)

[Claims] 1. A double-sided simultaneous polishing apparatus in which a disk-shaped workpiece is sandwiched between superposed portions of two flat polishing plates provided opposite to each other and polished, The rotation axis and the rotation axis of the second polishing plate are horizontal and parallel to each other with respect to the installation surface of the double-sided simultaneous polishing apparatus, and are at different positions, and the first polishing plate and the second polishing plate are So that the rotation axis of the disk-shaped workpiece sandwiched between the superimposed portions is parallel to the rotation axis of the first and second polishing platens and disposed at an intermediate position between both rotation axes, A carrier for holding the workpiece is arranged, and a mechanism for rotating the first polishing plate, the second polishing plate, and the three members together in the same direction is provided. A static pressure holding member comprising a pair of static pressure pads facing the outside of both polishing plates so as to sandwich a portion overlapping with the second polishing plate. , A double-sided simultaneous polishing apparatus. 2. The static pressure pad according to claim 1, wherein a static pressure pocket is provided on a surface of the pad facing the polishing plate, and a discharge port of a static pressure fluid is provided inside the static pressure pocket. Double-sided simultaneous polishing equipment. 3. The apparatus according to claim 1, further comprising a mechanism for arbitrarily setting a distance between a rotation axis of said first polishing plate and a rotation axis of said second polishing plate. A double-sided simultaneous polishing apparatus as described. 4. A mechanism for forcibly rotating one or two of the first polishing plate, the second polishing plate, and the carrier among the three members, and the remaining two members or one of the carriers is a predetermined member. The double-sided simultaneous polishing apparatus according to any one of claims 1 to 3, further comprising a mechanism that is freely held around the rotation axis. 5. The apparatus according to claim 1, further comprising a mechanism for forcibly driving each of said first polishing plate, said second polishing plate and said carrier at a constant rotational speed. Double-sided simultaneous polishing equipment. 6. The apparatus according to claim 1, wherein one of said two polishing plates or one of said carriers is provided with a rotating shaft swinging mechanism for swinging in parallel to a polishing surface. 5. The double-sided simultaneous polishing apparatus according to any one of 5.