Workpiece polishing device and workpiece polishing method

Abstract

To provide a workpiece polishing device capable of polishing a workpiece to a desired shape with a simple configuration in accordance with a purpose by pressing a workpiece to a polishing pad with an intended pressing force; and to provide a workpiece polishing method.SOLUTION: A workpiece polishing device 10 comprises a polishing head 12, and a drive part 64 that vertically moves the polishing head 12. The polishing head 12 includes: a head base part 20 having a shaft part 20c on a lower surface; a workpiece guide 22 that can vertically move to the head base part 20; a swing plate 34 pivoted swingably to the shaft part 20c; a holding plate 36 disposed at a lower end of the shaft part 20c; an elastic sheet body 44 that covers a lower part of the holding plate 36; a first fluid chamber 46 between the elastic sheet body 44 and the holding plate 36; and a first channel 48. The workpiece polishing device is configured to be capable of mechanically pressing a workpiece W with the swing plate 34 by controlling a height position of the head base part 20 during polishing of the workpiece W with a control part 62 driving and controlling the drive part 64.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a workpiece polishing apparatus and a workpiece polishing method. [Background technology]

[0002] A workpiece polishing device is known that presses a workpiece held on the underside of a polishing head provided above a platen against a polishing pad attached to the upper surface of the platen, and polishes the workpiece by moving the platen and the polishing head relative to each other (Patent Document 1: JP 2010-240767 A).

[0003] In the workpiece polishing device exemplified in Patent Document 1, the polishing head comprises a head member that forms the outer part of the polishing head, and a holding plate that is suspended from the head member via an elastic member so as to be movable up and down, and a fluid chamber is defined between the head member and the holding plate. When fluid is supplied into the fluid chamber and pressurized, the holding plate is pressed downward, and the workpiece held on the underside of the holding plate is pressed against a surface plate (polishing surface) and polished. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-240767 Summary of the Invention [Problem to be solved by the invention]

[0005] As exemplified by Patent Document 1, in a workpiece polishing device that pressurizes a fluid chamber to pressurize a workpiece from above, a completely uniform pressing force is not necessarily applied to the entire area of ​​the workpiece. For example, the pressing force applied to the peripheral portion of the workpiece is generally weaker than that applied to the center portion. To address this issue, a configuration in which the fluid chamber is divided into multiple sections and the pressing force is controlled for each predetermined area of ​​the workpiece is considered. However, this configuration has the problem of being complicated. Furthermore, separating the fluid chambers with a partition or the like reduces the pressing area of ​​each fluid chamber, making it difficult to precisely adjust both the pressing range and pressing force. Therefore, there has been a demand for a workpiece polishing device that has a simple configuration and can press any area of ​​the workpiece with the intended pressing force. [Means for solving the problem]

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a workpiece polishing device and a workpiece polishing method that have a simple configuration and can press a workpiece against a polishing pad with an intended pressing force to polish it into a desired shape according to the purpose.

[0007] The present invention solves the above problems by the solution means described below as one embodiment.

[0008] The workpiece polishing apparatus according to the present invention comprises a surface plate having a polishing pad affixed to its upper surface and rotating within a horizontal plane, a polishing head provided above the surface plate so as to be movable up and down and rotatable, which holds a workpiece on its lower surface and rotates it while pressing it against the polishing pad to polish it, a head shaft fixed to the upper surface of the polishing head, a drive unit which moves and rotates the head shaft up and down to move and rotate the polishing head up and down, and a control unit which drives and controls the drive unit, and the polishing head comprises a base top plate to which the head shaft is fixed at the center of its upper surface, a head base portion having a ring-shaped side wall portion extending downward from the outer edge of the base top plate and a shaft portion protruding from the center of the lower surface of the base top plate, and a workpiece support member located below the head base portion and provided so as to be movable up and down relative to the head base portion via a first suspending member. the workpiece polishing device according to the present invention comprises a work guide, a swinging plate located below the work guide and swingably supported on the shaft, a holding plate provided at the lower end of the shaft, an elastic sheet body fixed to the work guide at its peripheral portion so as to cover the lower side of the holding plate, holding the workpiece on its underside and pressing the workpiece, a first fluid chamber defined between the elastic sheet body and the holding plate, and a first flow path connected to a pressure adjustment mechanism driven and controlled by the control unit and supplying fluid to the first fluid chamber, wherein the control unit drives and controls the drive unit to control the height position of the head base unit when the workpiece is polished, thereby allowing the swinging plate to mechanically press the workpiece via the elastic sheet body.

[0009] The term "during polishing" used here means "after the work guide comes into contact with the polishing pad."

[0010] According to this, when polishing a workpiece, by lowering the head base portion while the work guide is in contact with the polishing pad, the pressing force from the head base portion is transmitted to the swing plate via the shaft portion, and the swing plate can mechanically press the workpiece via the elastic sheet body. Therefore, the swing plate can press areas (e.g., the peripheral edge of the workpiece) where it is difficult to obtain sufficient pressing force using a configuration that presses the entire workpiece with fluid pressure. This configuration can precisely control the pressing force by controlling the height position of the polishing head, and also simplifies the configuration because it does not require the installation of more fluid chambers than necessary or the use of separation walls, etc.

[0011] Furthermore, by lowering the head base unit while the first fluid chamber is under vacuum (negative pressure), the workpiece W can be mechanically pressed by the holding plate through the elastic sheet. Therefore, by appropriately setting the pressing positions of the oscillating plate and the holding plate, or by appropriately combining the pressing force due to the fluid pressure with the mechanical pressing force of the oscillating plate and the holding plate, the workpiece can be polished to a desired shape according to the purpose. Furthermore, the oscillating plate oscillates when it contacts the workpiece through the elastic sheet, so that its contact surface is always kept parallel to the workpiece, allowing the workpiece to be pressed with a uniform pressing force. Therefore, it is possible to polish a predetermined portion of the workpiece stably and reliably.

[0012] It is also preferable that the polishing head further includes a sensor for detecting the height position of the head base unit during polishing of the workpiece, and the control unit controls the drive unit so that the height position of the head base unit detected by the sensor is the required height position. In this way, the height position of the lowered head base unit can be directly detected and controlled by the sensor during polishing of the workpiece, thereby accurately positioning the polishing head at the required height position. Furthermore, by detecting and controlling the height position of the polishing head at a position very close to the workpiece, which is the object to be polished, it is possible to minimize the effects of dimensional errors and assembly errors of the polishing head and each component related to its vertical movement drive mechanism, thereby enabling accurate positioning. Therefore, it is possible to more accurately control the pressing force applied to the workpiece by the swing plate and the holding plate.

[0013] The sensor may be configured as a length measuring sensor that detects the vertical distance between the head base portion and the work guide as the height position of the head base portion. The sensor may be configured as a length measuring sensor that detects the vertical distance between the head base portion and the polishing pad as the height position of the head base portion.

[0014] Furthermore, it is preferable that the drive unit has a servo motor controlled by the control unit as a vertical movement drive mechanism for moving the head axis up and down, and further includes at least one of a current detector for detecting the value of a current flowing through the servo motor and an encoder for detecting the number of rotations or the rotation angle of the servo motor, and the control unit controls the drive unit so that the value detected by the current detector or the encoder becomes a required value or is kept within a required range. In this way, by directly detecting and controlling the height position of the polishing head with a sensor and further controlling the driving force and driving amount of the drive source for moving the polishing head up and down, it is possible to more accurately control the pressing force of the swing plate and the holding plate against the workpiece.

[0015] The vertical movement drive mechanism is preferably configured to include a spline mechanism. A servo mechanism including a spline mechanism can move the head shaft up and down with high precision, enabling the polishing head (head base portion) to be positioned more accurately at the desired position.

[0016] Furthermore, it is preferable that the swing plate has a pressing ring on its underside that presses the workpiece via the elastic sheet. This allows the pressing force of the swing plate to be transmitted to the pressing ring, which then presses the workpiece via the elastic sheet. Therefore, the pressing area of ​​the swing plate can be easily and freely set by the arrangement of the pressing ring (the mounting position on the underside of the swing plate), and it becomes possible to reliably press a predetermined area of ​​the workpiece or a predetermined area of ​​the polishing pad outside the workpiece with the intended pressing force.

[0017] The pressing ring is preferably disposed at a position where it presses the peripheral edge of the workpiece, thereby making it possible to reliably press the peripheral edge of the workpiece with the intended pressing force, which is difficult to achieve with a configuration in which the entire workpiece is pressed by fluid pressure.

[0018] The polishing head further includes a second fluid chamber defined between the lower surface of the head base and the upper surface of the work guide, and a second flow path for supplying fluid to the second fluid chamber. The work guide preferably has a retainer ring on its lower surface that abuts against the polishing pad in the outer region of the workpiece when polishing the workpiece. This allows the retainer ring to surround the workpiece during polishing, preventing the workpiece from sliding sideways (protruding radially). Furthermore, when polishing the workpiece, a pressing force is applied to the workpiece, causing the polishing pad on the workpiece's polished surface to become recessed. The edge of the workpiece comes into contact with the peripheral wall of the recess, making the edge prone to over-polishing. In response, the retainer ring presses the polishing pad in the outer region of the workpiece so that it is approximately flush with the polished surface of the workpiece, preventing over-polishing of the edge of the workpiece. Furthermore, adjusting the pressing force of the retainer ring can change the tension of the elastic sheet body, thereby affecting the polished shape of the workpiece W.

[0019] Further, a workpiece polishing method according to the present invention is a method for polishing a workpiece by holding the workpiece on a polishing head, lowering the workpiece while rotating it, and pressing the workpiece against a polishing pad from above to polish the workpiece, the method comprising: at least one of a driving force and a driving amount of a driving source of a vertical movement drive mechanism that moves the polishing head up and down; The vertical distance between the polishing head and the polishing pad The height position of the polishing head during polishing of the workpiece is controlled to thereby control the pressing force of the polishing head against the workpiece. In addition, the workpiece polishing method of the present invention is a method of polishing a workpiece in which a polishing head holds a workpiece and lowers it while rotating, and presses it against a polishing pad from above to polish the workpiece, and is characterized in that the pressing force of the polishing head against the workpiece when polishing the workpiece is controlled by controlling at least one of the driving force and driving amount of the driving source of the up-and-down movement drive mechanism that moves the polishing head up and down, and the height position of the polishing head when polishing the workpiece by controlling the vertical distance between a head base portion in the polishing head that is connected to the up-and-down movement drive mechanism and moved up and down by the driving source, and a work guide that is provided below the head base portion via a hanging member so as to be able to move up and down relative to the head base portion.

[0020] The term "during polishing" used here means "after the work guide comes into contact with the polishing pad."

[0021] This makes it possible to accurately control the pressing force on the workpiece by controlling the height position of the polishing head while controlling the driving force and driving amount of the drive source that moves the polishing head up and down. [Effects of the Invention]

[0022] According to the present invention, with a simple configuration, it is possible to press a workpiece against a polishing pad with an intended pressing force and polish it into a desired shape according to the purpose. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic view (front cross-sectional view) showing an example of a polishing head of a workpiece polishing apparatus according to an embodiment of the present invention. [Figure 2] 2 is a schematic view (front cross-sectional view) showing an example of a drive unit of the polishing head shown in FIG. 1. FIG. [Figure 3] FIG. 2 is an explanatory diagram for explaining the arrangement of the polishing head and the surface plate shown in FIG. 1, and is a schematic diagram (plan view) showing an example of a workpiece polishing apparatus according to an embodiment of the present invention. [Figure 4] 10 is a photograph showing the load distribution on a workpiece when the workpiece is pressed by a workpiece polishing method according to an embodiment of the present invention using a workpiece polishing apparatus according to an embodiment of the present invention. [Figure 5] 10 is a photograph showing the load distribution on a workpiece when the workpiece is pressed by a workpiece polishing method according to an embodiment of the present invention using a workpiece polishing apparatus according to an embodiment of the present invention. [Figure 6] 10 is a graph showing the amount of polishing of a workpiece when the workpiece is pressed by a workpiece polishing method according to an embodiment of the present invention using a workpiece polishing apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. A workpiece polishing apparatus 10 (hereinafter sometimes referred to as "polishing apparatus 10") according to this embodiment is an apparatus that holds a flat (particularly disk-shaped) workpiece W such as a wafer (e.g., a silicon wafer) by a polishing head 12 and presses it against a surface plate 14 while moving the polishing head 12 and the surface plate 14 relative to each other to polish it.

[0025] 1 is a schematic diagram (front cross-sectional view) showing an example of a polishing head 12. The polishing head 12 holds and rotates a workpiece W horizontally on its lower surface with the surface Wa to be polished facing downward, and polishes the workpiece W by pressing it against a polishing pad 16 on the upper surface of a surface plate 14 that rotates in a horizontal plane.

[0026] The head base portion 20 includes a base top plate 20a, a ring-shaped sidewall portion 20b extending downward from the outer edge of the base top plate 20a, and a shaft portion 20c protruding downward from the center of the lower surface of the base top plate 20a. A head shaft 18 extending upward is fixed to the center of the upper surface of the head base portion 20. The head shaft 18 is rotated about its axis by a drive unit 64, which will be described later. Therefore, the head base portion 20 rotates together with the head shaft 18 around the head shaft 18. The head shaft 18 is also moved up and down by the drive unit 64, which will be described later. Therefore, the head base portion 20 moves up and down together with the head shaft 18.

[0027] Next, a work guide 22 is provided below the head base portion 20 and includes a guide top plate 22a, a pressure ring portion 22b extending downward from the outer edge of the guide top plate 22a, and a retainer ring 22c provided on the underside of the pressure ring portion 22b. When the workpiece W is polished, the work guide 22 surrounds the workpiece W with the retainer ring 22c, and holds the workpiece W on the underside of an elastic sheet body 44, which will be described later.

[0028] The outer periphery of the work guide 22 (guide top plate 22a) is connected to the side wall 20b of the head base portion 20 via a first suspending member 24. Also, the inner periphery is connected to the outer periphery of the shaft portion 20c of the head base portion 20 via a second suspending member 28. Also, the first suspending member 24 and the second suspending member 28 may be configured as an integral unit as shown in FIG. 1, but of course they may also be configured separately (not shown).

[0029] As described above, the work guide 22 is connected to the head base portion 20 via the first suspending member 24 and the second suspending member 28. In this embodiment, the first and second suspending members 24 and 28 are both formed from diaphragms made of a rubber material, and the work guide 22 is configured to move up and down relative to the head base portion 20 via changes in the shape of the first and second suspending members 24 and 28. When the head base portion 20 rotates, the rotational force is transmitted to the work guide 22 via the first and second suspending members 24 and 28, causing the work guide 22 to rotate. The first and second suspending members 24 and 28 may be configured in any manner and made of any material, as long as they can suspend the work guide 22 so that it can move up and down. In other words, they are not limited to diaphragms, and may be made of, for example, bellows. Furthermore, they are not limited to rubber materials, and may be made of resin, metal, or other materials.

[0030] A second fluid chamber 30 is defined between the lower surface of the head base portion 20 (base top plate 20a) and the upper surfaces of the work guide 22 (and the first and second suspending members 24, 28). A fluid can be supplied to the second fluid chamber 30 via a second flow path 32 connected to a pressure adjustment mechanism 96. This allows the work guide 22 to be pushed downward by creating a positive pressure in the second fluid chamber 30, or to be lifted upward by creating a negative pressure in the second fluid chamber 30. This allows the pressure applied to the retaining ring 22c to be increased or decreased, or adjusted accordingly. Therefore, the retaining ring 22c can press the polishing pad 16, which is the outer region of the workpiece W, so that it is substantially flush with the polished surface Wa of the workpiece W. In this embodiment, the fluid is air, and the air pressure in the second fluid chamber 30 is adjusted. However, this configuration is not limited to this, and the fluid may be water, oil, or the like. Although the second fluid chamber 30 is not a required configuration in the present application, if the second fluid chamber 30 is provided, the first and second suspension members 24, 28 are configured to form an airtight space between the lower surface of the head base portion 20 and the upper surface of the work guide 22.

[0031] Next, a swing plate 34 is disposed inside the work guide 22. The swing plate 34 is located below the work guide 22 and is pivotally supported at its center by the shaft 20c. This allows the swing plate 34 to swing up and down in an arc shape around the shaft 20c. As an example, a spherical bearing or the like is provided as the swing mechanism 40. The swing plate 34 is swingably connected to the work guide 22 on its outer periphery via a third suspending member 38. This defines a third fluid chamber 56, which will be described later. However, since the third fluid chamber 56 is not an essential component in this application, the third suspending member 38 is not necessarily provided. Here, the third suspending member 38 is formed from a diaphragm made of a rubber material, similar to the first and second suspending members 24 and 28, but its configuration and material are not limited. The swing plate 34 moves up and down in conjunction with the head base portion 20 and rotates around the shaft portion 20c.

[0032] A downwardly protruding pressing ring 42 is provided on the underside of the swing plate 34. When the workpiece W is polished, the pressing force from the lowered head base portion 20 is transmitted via the shaft portion 20c to the swing plate 34 and then to the pressing ring 42, mechanically pressing the workpiece W via the elastic sheet body 44. However, since the pressing ring 42 is not an essential component in the present application, the swing plate 34 may be configured to press the workpiece W. Meanwhile, the shape, size, and arrangement (mounting position on the underside of the swing plate 34) of the pressing ring 42 are not limited. Therefore, the pressing ring 42 allows the swing plate 34 to easily and freely set the pressing area, enabling mechanical pressing of a predetermined area of ​​the workpiece W. The pressing ring 42 according to this embodiment is positioned to press the peripheral edge of the workpiece W. The pressing area of ​​the swing plate 34 (pressing ring 42) is not limited to the area on the workpiece W, and may be configured to press a predetermined area on the polishing pad 16. The pressing ring 42 is preferably formed using a material that can serve as a buffer, such as rubber.

[0033] Next, a holding plate 36 is fixed to the lower end of the shaft portion 20c. An elastic sheet 44 has its peripheral edge 44a fixed to the work guide 22 (the lower surface of the pressing ring portion 22b) so as to cover the lower part of the holding plate 36 (and the swing plate 34). A resin retainer ring 22c is provided on the lower surface of the pressing ring portion 22b, sandwiching the elastic sheet 44. The elastic sheet 44 is formed, for example, using a flexible resin material such as PET (polyethylene terephthalate). However, it may be formed of other materials.

[0034] A first fluid chamber 46 is defined between the elastic sheet body 44 and the holding plate 36 (and the swing plate 34). A first flow path 48 is provided, connecting the first fluid chamber 46 to the pressure adjustment mechanism 96 via a pipe 21 or the like provided in the shaft portion 20c. By creating a vacuum (negative pressure) within the first fluid chamber 46, the workpiece W can be adsorbed and held on the underside of the elastic sheet body 44. This allows the workpiece W to be picked up, or the workpiece W can be mechanically pressed by the holding plate 36 via the elastic sheet body 44 when polishing the workpiece W. On the other hand, by supplying a fluid into the first fluid chamber 46 to create a positive pressure, the workpiece W can be pressed by the pressure of the fluid via the elastic sheet body 44. In this embodiment, the fluid is air, and the air pressure within the first fluid chamber 46 is adjusted. However, this configuration is not limited to this, and the fluid may be, for example, water, oil, or the like. 1, in forming the first fluid chamber 46, the holding plate 36 and the swinging plate 34 may be connected at an appropriate position via a fourth suspending member 50 or the like. Here, the fourth suspending member 50 is also formed from a diaphragm made of a rubber material, like the first, second and third suspending members 24, 28 and 38, but the configuration and material thereof are not limited.

[0035] A third fluid chamber 56 is defined between the outer periphery of the swing plate 34 and the inner periphery of the work guide 22 (pressure ring portion 22b). Fluid can be supplied to the third fluid chamber 56 via a third flow path 58 connected to a pressure adjustment mechanism 96. The third fluid chamber 56 is connected to the first fluid chamber 46 via a communication path (not shown), which can be opened or closed. Therefore, the third fluid chamber 56 is pressurized via the first flow path 48 when the communication path is open, and via the third flow path 58 when the communication path is closed. While the third fluid chamber 56 is not essential to the present application, when the third fluid chamber 56 is provided and pressurized, the inner edge of the retainer ring 22c can be pressed by fluid pressure via the elastic sheet 44, and the pressing force can be adjusted independently from other regions. As a result, for example, the polishing pad 16 in the outer region of the workpiece W can be pressed more strongly. In this embodiment, the fluid is air, and the air pressure in the third fluid chamber 56 is adjusted, but the present invention is not limited to this configuration, and the fluid may be, for example, water, oil, or the like.

[0036] A sensor 60 is provided outside the polishing head 12 having the above-described configuration to detect the height position of the head base portion 20 when polishing the workpiece W. Specifically, the sensor 60 is provided as a length measuring sensor that detects the "vertical distance X between the head base portion 20 and the work guide 22 (for example, the vertical distance between the lower end of the side wall portion 20b of the head base portion 20 and the shoulder portion (edge ​​portion) of the work guide 22 as shown by arrow A in FIG. 1)" or the "vertical distance Y between the head base portion 20 and the polishing pad 16 (for example, the distance between the lower end of the side wall portion 20b of the head base portion 20 and the upper surface of the polishing pad 16 as shown by arrow B in FIG. 1)" as the height position of the head base portion 20. The sensor 60 is connected to a control unit 62 which drives and controls a drive unit 64 (servo motor 72 described later) of the polishing head 12 (see Figures 1 and 2). When information (detection value) from the sensor 60 is sent to the control unit 62, the control unit 62 drives and controls the drive unit 64 to move the polishing head 12 up and down and adjust the height position of the polishing head 12 so that the distance X (height position of the head base portion 20) detected by the sensor 60 becomes the required distance (height position).

[0037] In a conventional workpiece polishing device, for example, a distance measuring sensor is attached to a support member or the like that is provided above the polishing head and suspends the polishing head so that it can move up and down and rotate. The distance between the support member (distance measuring sensor) and the vertical movement drive mechanism of the polishing head, which is provided further above, and the vertical distance between the support member (distance measuring sensor) and the polishing pad below are detected and adjusted to adjust the height position of the polishing head (not shown). In this configuration, the height position of the polishing head is detected and controlled from a position above the polishing head that is far from the workpiece. Therefore, errors in the position adjustment of the polishing head occur due to dimensional errors and assembly errors of each component from the detection position (control position) to the underside of the polishing head (i.e., the workpiece holding position). As a result, there is a risk that the height of the polishing head cannot be accurately positioned.

[0038] In contrast, the configuration of the sensor 60 according to this embodiment makes it possible to detect and control the height position of the polishing head 12 at a position extremely close to the workpiece W, which is the object to be polished. Therefore, the influence of dimensional errors and assembly errors of the polishing head 12 and the members related to its vertical movement drive mechanism 66 can be minimized, and the polishing head 12 can be accurately positioned at a required height position. The sensor 60 may be a known length measuring sensor such as an ultrasonic or laser type.

[0039] The position of the sensor 60 is not limited, and it may be provided at any position where the distance X or the distance Y can be detected. Furthermore, the number of sensors 60 is also not limited. In the case of a polishing apparatus 10 having a plurality of polishing heads 12 and surface plates 14 arranged thereon, as shown in Fig. 3, a sensor 60 may be provided for each polishing head 12, or a sensor 60 may be provided for only one polishing head 12, the detected value of that polishing head 12 may be recorded, and the position of the other polishing heads 12 may be adjusted based on this detected value. As will be described later, in Fig. 3, the polishing head 12 revolves around the axis 102a and moves sequentially over each surface plate 14, and a predetermined polishing is performed on each polishing head 12. Therefore, although a configuration in which a sensor 60 is provided for each surface plate 14 and detects the height position of each polishing head 12 on each surface plate 14 may be adopted, a configuration in which a sensor 60 is provided for only one surface plate 14 and the detected values ​​of each polishing head 12 that moves sequentially on that surface plate 14 are recorded, and the positions of each polishing head 12 on the other surface plates 14 are adjusted based on these detected values ​​may be adopted. As described above, in this embodiment, the height position of the polishing head 12 is detected and controlled at a position very close to the workpiece W, which is the object to be polished. Therefore, even if a sensor 60 is not provided for every polishing head 12 or surface plate 14, the height position can be positioned at a required position relatively accurately, with little influence from dimensional errors, assembly errors, etc., for each polishing head 12.

[0040] Next, the drive unit 64 of the polishing head 12 will be described. Fig. 2 is a schematic diagram (front cross-sectional view) showing an example of the drive unit 64. The drive unit 64 moves the polishing head 12 up and down and rotates the polishing head 12 by moving the head shaft 18 up and down and rotating the head shaft 18. The drive unit 64 includes a vertical movement drive mechanism 66 and a rotation drive mechanism 68.

[0041] The vertical movement drive mechanism 66 includes a drive source 72 controlled by the control unit 62 and a linear motion device 70 driven by the drive source 72. In this embodiment, as shown in FIG. 2, the drive source 72 is configured as a servo motor 72, and the linear motion device 70 is configured as a ball screw spline mechanism 70. In the ball screw spline mechanism 70, the upper end of a spline shaft 70a, which is spline-engaged with a spline outer cylindrical portion 70b, is threadedly engaged with a ball screw shaft (not shown). The ball screw shaft is driven by the servo motor 72 via a timing belt or a gear mechanism (not shown), thereby driving the spline shaft 70a in the vertical direction. The spline outer cylindrical portion 70b is fixed to a base frame 74. The lower end of the spline shaft 70a is fixed to a transmission frame 76, which connects upper and lower support plates 76a, 76b with a shaft 76c. The upper end of the head shaft 18 is connected to the lower support plate 76b via a connecting portion 78 so as to be rotatable about its axis. 2, a current detector 80 is provided to detect the value of a current flowing through the servo motor 72. The current detector 80 is connected to the control unit 62, and the control unit 62 is configured to control the torque of the servo motor 72 in accordance with information (detected value) from the current detector 80. Details will be described later.

[0042] The rotation drive mechanism 68 includes a drive source 82 that is driven and controlled by the control unit 62, and rotates the head shaft 18. In this embodiment, as shown in FIG. 2, the drive source 82 is configured as a servo motor 82, and is provided with a rotating unit 88 that is rotated via a first pulley 84a, a belt 86, and a second pulley 84b or via a gear mechanism (not shown). The rotating unit 88 and the head shaft 18 are spline-engaged to allow the head shaft 18 to move up and down, and the rotation of the rotating unit 88 is transmitted to the head shaft 18, causing it to rotate about its axis. That is, in this embodiment, the rotating unit 88 is configured as a spline outer cylinder portion 88 of a rotary ball spline mechanism 89 that also serves as a guide mechanism for the linear motion device 70, and the head shaft 18, configured as a spline shaft 18, moves up and down and rotates. The rotary ball spline mechanism 89 includes a spline outer cylinder portion 88 and a flange portion 92 that rotatably supports the spline outer cylinder portion 88, and is fixed to a support box 90 via the flange portion 92. The servo motor 82 is also fixed to the support box 90.

[0043] The configurations of the vertical movement drive mechanism 66 and the rotation drive mechanism 68 are not limited, and any configuration that moves the head shaft 18 up and down and rotates the head shaft 18 may be used. As an example, the vertical movement drive mechanism 66 may be a linear motor or the like in which the drive source 72 and the linear motion device 70 are integrated, or a linear motor actuator or the like in which a guide mechanism for the linear motion device 70 is also integrated may be used. In this case, the rotation drive mechanism 68 may be a device that directly rotates the head shaft 18 using a spindle or the like, or a linear motor actuator or the like with a built-in rotation drive mechanism 68 may be used (both not shown). As a modification of this embodiment, the ball screw spline mechanism 70 and the rotary ball spline mechanism 89 may have the same spline shafts 70a and 18. Alternatively, instead of the rotary ball spline mechanism 89, a linear slide or the like may be provided as a guide mechanism for the linear motion device 70, and a spindle or the like may be provided as the rotation drive mechanism 68, so that the guide mechanism and the rotation drive mechanism 68 are configured separately (both not shown). However, as in this embodiment, by configuring the vertical movement drive mechanism 66 with spline mechanisms 70, 89 (including ball spline mechanisms and rotary ball spline mechanisms), it becomes possible to position the head shaft 18 at a height position with high precision and accuracy.

[0044] 2, the head shaft 18 is hollow, and a pipe 93 passes through this hollow portion. The upper end of the pipe 93 is connected to a rotary joint 94, and the rotary joint 94 is connected to a pressure adjustment mechanism 96 having a fluid supply source (not shown) through a pipe 95. Meanwhile, the pipe 93 in the head shaft 18 is connected to each of the fluid chambers 30, 46, and 56 in the polishing head 12, thereby forming first, second, and third flow paths 32, 48, and 58 that communicate the pressure adjustment mechanism 96 with each of the fluid chambers 30, 46, and 56, and enabling compressed air to be supplied to each of the fluid chambers 30, 46, and 56 (see FIGS. 1 and 2). In FIG. 1, for ease of visualization, the second and third flow paths 32, 58 other than the first flow path 48 are shown by arrows leading directly from outside the polishing head 12 to each of the fluid chambers 30, 56 without passing through the pipe 93. The pressure adjustment mechanism 96 is connected to the control unit 62 and is capable of adjusting the pressure in each of the fluid chambers 30, 46, 56.

[0045] Next, the surface plate 14 is formed in a disk shape in a plan view (see FIG. 3), and a polishing pad 16 is affixed to its upper surface. The surface plate 14 is provided with a rotation drive mechanism (not shown) and configured to be rotatable about an axis in a horizontal plane. It is also provided with a slurry supply unit (not shown) that supplies polishing slurry onto the polishing pad 16. Therefore, when polishing the workpiece W, the workpiece W is supplied with slurry, and the polishing head 12 and the surface plate 14, which rotate relative to each other, move relative to each other, causing the workpiece W and the polishing pad 16 to slide against each other, thereby polishing the workpiece W. For example, the polishing pad 16 (polishing cloth) may be made of a polyurethane sheet or a nonwoven fabric sheet impregnated with polyurethane. However, it may be made of other materials.

[0046] Next, we will explain the arrangement of the polishing heads 12 and the platens 14. There are no limitations on the arrangement of the polishing heads 12 and the platens 14 in the polishing apparatus 10 of the present application, and there are no limitations on the number of polishing heads 12 and the platens 14 either. However, as an example, they can be arranged as follows.

[0047] FIG. 3 is an explanatory diagram showing an example of the arrangement of the polishing heads 12, and is a schematic diagram (plan view) showing an example of a polishing apparatus 10 according to this embodiment. In the polishing apparatus 10 according to this embodiment, a temporary table 100 on which the workpiece W is loaded and unloaded and multiple (three in this embodiment) surface plates 14 are radially arranged on the upper surface of a base 98. Above the base 98, multiple polishing heads 12 (four in this embodiment) are suspended and supported by support members 102 (the aforementioned support box 90 and base frame 74) so ​​that each head shaft 18 is independently movable up and down and rotatable. The polishing heads 12 are radially arranged with their axes 102a aligned with the temporary table 100 and each surface plate 14. The support member 102 has a rotation drive mechanism (not shown) and is configured to be rotatable (including intermittently rotatable forward and reverse) about the axis 102a. According to this, by rotating the support member 102, the polishing head 12 can be made to revolve (including revolving intermittently in forward and reverse directions) around the axis 102a.

[0048] Therefore, by rotating the support member 102, the polishing head 12 can be moved sequentially from the temporary table 100 to each surface plate 14. As a result, the polishing head 12 holds and takes out (loads) the workpiece W placed on the temporary table 100, then moves sequentially to each surface plate 14 to perform a predetermined polishing (e.g., rough polishing, medium polishing, finish polishing), and then returns to the temporary table 100 to place (unload) the polished workpiece W. This completes a series of polishing steps. The direction and order of movement (rotation) of the polishing head 12 are not limited at all. Furthermore, the number of surface plates 14 and polishing heads 12 is not limited, and the number of surface plates 14 and the number of polishing heads 12 do not have to be the same. Furthermore, the temporary table 100 may be provided with a loading station where loading is performed and an unloading station where unloading is performed, separately.

[0049] Next, the workpiece polishing method according to this embodiment will be described using the workpiece polishing device 10 according to this embodiment as an example.

[0050] (Holding and pressing the workpiece W) First, the polishing head 12 is positioned on the temporary table 100, and the first fluid chamber 46 is evacuated to suction and hold the workpiece W on the underside of the elastic sheet 44. Next, the polishing head 12 is moved to position the workpiece W on the surface plate 14, and the drive unit 64 is used to lower the polishing head 12. When the retainer ring 22c on the underside of the work guide 22 abuts against the polishing pad 16, which is the outer region of the workpiece W, the workpiece W is surrounded and held on the underside of the elastic sheet 44. Next, the polishing head 12 is further lowered, and the workpiece W is pressed against the elastic sheet 44 by the holding plate 36, or a positive pressure is created in the first fluid chamber 46 to press the workpiece W against the elastic sheet 44 with fluid pressure. Slurry is then supplied to the workpiece W, and the surface plate 14 and polishing head 12 are rotated to bring the polishing pad 16 into sliding contact with the workpiece W, thereby polishing the polished surface Wa of the workpiece W. By adjusting the air pressure in the first fluid chamber 46 and the height position of the polishing head 12, the pressing force against the workpiece W can be adjusted, and the polished shape of the workpiece W can be affected.

[0051] (Pressing the polishing pad on the outer area of ​​the workpiece) During polishing of the workpiece W, the retainer ring 22c prevents the rotating workpiece W from sliding sideways (protruding radially). The polishing pad 16, which forms the outer region of the workpiece W, is pressed so as to be substantially flush with the polished surface Wa of the workpiece W, preventing over-polishing of the edge portion of the workpiece W. The pressing force of the retainer ring 22c can be adjusted via the second fluid chamber 30, thereby changing the tension of the elastic sheet 44 and affecting the polished shape of the workpiece W. Because the air pressures of the first fluid chamber 46 and the second fluid chamber 30 are controlled separately, the pressing force on the workpiece W and the pressing force of the retainer ring 22c on the polishing pad 16 in the outer peripheral region of the workpiece W can be stably controlled separately (i.e., independently). The air pressure from the third fluid chamber 56 can press the inner edge of the retainer ring 22c via the elastic sheet 44, and this pressing force can be adjusted independently of other regions. As a result, for example, the polishing pad 16 in the outer region of the workpiece W can be pressed more strongly.

[0052] (Pressing the periphery of the workpiece W) Furthermore, when polishing the workpiece W, if the polishing head 12 is lowered by the drive unit 64 with the workpiece guide 22 (retainer ring 22c) in contact with the polishing pad 16, the swinging plate 34 is lowered via the head base unit 20 (shaft 20c). Then, the pressing ring 42 provided on the underside of the swinging plate 34 comes into contact with the peripheral edge of the workpiece W via the elastic sheet body 44, and the pressing force from the head base unit 20 is transmitted to the swinging plate 34 (pressing ring 42) via the shaft 20c, so that the pressing ring 42 presses the peripheral edge of the workpiece W against the polishing pad 16 via the elastic sheet body 44, thereby polishing the workpiece W. This makes it possible to mechanically press the peripheral edge of the workpiece W, which is difficult to achieve with a configuration in which the entire workpiece W is pressed by fluid pressure. This configuration allows for precise control of the pressing force by controlling the height position of the polishing head 12 (head base portion 20), and also simplifies the configuration because it does not require the installation of more fluid chambers than necessary or the separation of fluid chambers by partitions or the like.

[0053] Furthermore, this mechanism is a mechanism in which, with the work guide 22 (retainer ring 22c) in contact with the polishing pad 16 and its height position being determined, the head base portion 20 is moved up and down (the height position is adjusted), and the pressing ring 42 of the swing plate 34 presses the peripheral portion of the workpiece W via the elastic sheet body 44. Therefore, the pressing of the peripheral portion of the workpiece W and the pressing of the polishing pad 16 in the outer region of the workpiece W (pressing by the work guide 22) can be stably controlled separately (i.e., independently).

[0054] Furthermore, in this mechanism, when the pressing ring 42 contacts the workpiece W, the swing plate 34 swings, keeping the pressing surface of the pressing ring 42 parallel to the workpiece W at all times, allowing the workpiece W to be pressed with a uniform pressing force. Furthermore, the vertical movement of the polishing head 12 (head base portion 20) is controlled with high precision via the spline mechanisms 70 and 89 by the servo motor 72, which is driven and controlled by the control unit 62 in response to the detection value of the sensor 60, allowing the workpiece W to be pressed with an optimal pressing force. As a result, the peripheral edge of the workpiece W can be polished stably and reliably. As described above, by combining various pressing forces, each of which has a different effect on the polished shape of the workpiece W, it is possible to polish the workpiece W to a desired shape.

[0055] (Control of pressing force against workpiece W) As an example, the sensor 60 according to this embodiment detects the vertical distance X (see arrow A in FIG. 1) between the work guide 22, whose height position is determined, and the head base portion 20, which moves up and down while the work guide 22 is in contact with the polishing pad 16. As another example, the sensor 60 detects the vertical distance Y (see arrow B in FIG. 1) between the polishing pad 16 and the head base portion 20, which moves up and down while the work guide 22 is in contact with the polishing pad 16. Then, when the control unit 62 controls the drive unit 64 (servo motor 72) so that the distance X or the distance Y detected by the sensor 60 becomes the required distance, the polishing head 12 is moved up and down via the head shaft 18, and the height position of the head base portion 20 is adjusted. The sensor 60 may detect the distance from any position on the work guide 22 or the head base unit 20, from which the "distance in the vertical direction between the work guide 22, whose height position is fixed, and the head base unit 20, which moves up and down" or the "distance in the vertical direction between the polishing pad 16 and the head base unit 20, which moves up and down" can be detected. Therefore, the distance X and the distance Y are not limited to the distances indicated by the arrows A and B in FIG. 1.

[0056] This allows the height position of the polishing head 12 to be detected and controlled at a position extremely close to the workpiece W, which is the object to be polished. Therefore, the effects of dimensional errors and assembly errors of the polishing head 12 and the components related to its vertical movement drive mechanism 66 can be minimized, and the head shaft 18 can be moved up and down with high precision by the servo mechanism, allowing the polishing head 12 (head base portion 20) to be accurately positioned at the required position. As a result, the workpiece W can be pressed against the polishing pad 16 with the intended pressing force, allowing it to be polished to the desired shape according to the purpose.

[0057] Furthermore, when polishing the workpiece W, even when the polishing head 12 is not moving up and down, the polishing pad 16 receives a pressing force and sinks downward, which may change the vertical distance X between the head base portion 20 and the retaining ring 22c and the vertical distance Y between the head base portion 20 and the polishing pad 16. The sensor 60 can detect such changes, so that the pressure on the workpiece W and the pressure on the polishing pad 16 in the outer region of the workpiece W (pressing force by the work guide 22) can be appropriately optimized by adjusting the air pressure in the first fluid chamber 46 and the second fluid chamber 30 in addition to the height position of the polishing head 12.

[0058] Furthermore, the height position of the head base unit 20 can be constantly monitored by the sensor 60, and the control unit 62 can be configured to have a limiter function that limits the range of motion of the head base unit 20. This makes it possible to prevent the height position of the head base unit 20 from being too high and therefore unable to apply the required load to the workpiece W, or conversely, from being too low and therefore applying an excessive load to the workpiece W. As a result, the workpiece W can be polished with an optimal pressing force, further improving the polishing quality.

[0059] In addition to controlling the height position of the polishing head 12 using the sensor 60, this embodiment is configured to control the pressing force on the workpiece W by controlling the driving force of the driving source 72 of the vertical movement drive mechanism 66. That is, the control unit 62 determines the load on the holding plate 36 or the swing plate 34 (pressing ring 42), i.e., the workpiece W, when the head base unit 20 is lowered, via the current value detected by the current detector 80 flowing through the servo motor 72 of the vertical movement drive mechanism 66. The drive unit 64 (servo motor 72) is then driven and controlled so that the load on the workpiece W becomes a desired value or is kept within a desired range. This allows the height position of the polishing head 12 to be directly detected and controlled by the sensor 60, while also controlling the driving force of the driving source 72 that moves the polishing head 12 up and down, thereby enabling more accurate control of the pressing force on the workpiece W. Furthermore, limiting the driving force of the driving source 72 to a desired range prevents excessive pressing force from being applied to the workpiece W.

[0060] Furthermore, together with / instead of the current detector 80, an encoder 81 may be provided that detects the number of rotations or the rotation angle of the servo motor 72. This allows the height position of the polishing head 12 to be directly detected and controlled by the sensor 60, while also controlling the drive amount of the drive source 72 that moves the polishing head 12 up and down, thereby making it possible to more accurately control the pressing force on the workpiece W. Furthermore, by limiting the drive amount of the drive source 72 to a required range, it is possible to prevent excessive pressing force from being applied to the workpiece W. Furthermore, a position sensor or a load sensor may be provided for the linear motion device 70 in the vertical movement drive mechanism 66, and the height position of the polishing head 12 may be controlled based on the detected values ​​of these sensors together with the sensor 60 (neither is shown).

[0061] 4 and 5 are photographs showing the load distribution on a circular workpiece W when the workpiece W is pressed under predetermined polishing conditions using the workpiece polishing apparatus 10 according to the present embodiment described above and the workpiece polishing method according to the present embodiment. In the photographs, the load increases as the color changes from blue to red. On paper, the lighter the color (closer to the background color), the greater the load. However, since the red areas where the load is particularly heavy appear darker on paper, these areas are indicated by the symbol R as necessary. FIG. 4-I shows the state in which the polishing head 12 is lowered to bring the retainer ring 22c into contact with the polishing pad 16, which corresponds to the outer region of the workpiece W (denoted by symbol w1). FIG. 4-II shows the state in which the first fluid chamber 46 is then positively pressurized and the workpiece W is pressed by fluid pressure via the elastic sheet 44. The workpiece W area is designated by symbol w2. FIG. 4-III shows the state in which the polishing head 12 is then further lowered, thereby lowering the head base portion 20 and the swing plate 34 via the shaft portion 20c with the retainer ring 22c abutting against the polishing pad 16, and the pressing ring 42 presses the peripheral edge portion (indicated by symbol w3) of the workpiece W via the elastic sheet 44. FIG. 4-IV shows the state in which, with the communication passage between the first fluid chamber 46 and the third fluid chamber 56 closed, positive pressure is created within the third fluid chamber 56, and the inner edge portion (indicated by symbol w4) of the retainer ring 22c is pressed by the fluid pressure via the elastic sheet 44. As shown in FIG. 4, according to the workpiece polishing method of this embodiment, it can be seen that the intended area is reliably pressed in each of FIGS. 4-I, 4-II, 4-III, and 4-IV.

[0062] 5 shows the following polishing conditions: the polishing head 12 is lowered and the retainer ring 22c is brought into contact with the polishing pad 16, which corresponds to the outer region w1 of the workpiece W; a constant positive pressure is applied within the second fluid chamber 30 to press the region w1 via the elastic sheet 44; a constant positive pressure is applied within the first fluid chamber 46 to press the region w2 of the workpiece W via the elastic sheet 44; the polishing head 12 is then lowered to a predetermined height and the pressing ring 42 presses the peripheral edge w3 of the workpiece W via the elastic sheet 44 with a constant pressing force, closing the communication path between the first fluid chamber 46 and the third fluid chamber 56; and the third fluid chamber 56 is open to the atmosphere. Fig. 5 shows photographs showing the load distribution on the workpiece W when the polishing head 12 is further lowered in 0.2 mm increments to increase the pressing force of the pressing ring 42, based on the above-mentioned condition. In addition to the above w1, w2, and w3, the photograph also shows an inner edge w4 of the retainer ring 22c corresponding to the third fluid chamber 56.

[0063] Figure 5-I shows the polishing head 12, i.e., the pressure ring 42, at the reference height. Figure 5-II shows the polishing head 12 at a height of -0.2 mm from the reference height. Figure 5-III shows the polishing head 12 at a height of -0.4 mm from the reference height. Figure 5-IV shows the polishing head 12 at a height of -0.6 mm from the reference height. As shown in Figures 5-I to 5-IV, gradually increasing the pressure of the pressure ring 42 significantly increases the load applied to the peripheral edge w3 of the workpiece W corresponding to the pressure ring 42. Under these conditions, the load applied to the outer region w1 of the workpiece W as well as the peripheral edge w3 of the workpiece W increases. However, by adjusting the pressure in the third fluid chamber 56 without opening it to the atmosphere and adjusting the balance with the pressure in the second fluid chamber 30, it is possible to increase only the load applied to the peripheral edge w3 of the workpiece W.

[0064] FIG. 6 is a graph showing the amount of polishing for each workpiece W under the polishing conditions shown in FIG. 5. The horizontal axis represents the radius of the circular workpiece W, converted so that the center point is 0 and the outer periphery is 1.0. The vertical axis represents the amount of polishing, but units and scale values ​​are omitted here because only relative changes are required. As shown in FIG. 6, the amount of polishing for the workpiece W generally declined gradually from the center to the outer periphery. At the peripheral edge w3 of the workpiece W, when the pressure ring 42 was at the standard height, the amount of polishing decreased somewhat sharply toward the outer periphery. In contrast, when the height of the pressure ring 42 was lowered by 0.2 mm, the amount of polishing increased gradually toward the outer periphery, and the amount of polishing increased more steeply with each further 0.2 mm decrease. In this way, by changing the pressing force of the pressing ring 42, it is possible to selectively change the amount of polishing of the peripheral edge w3 of the workpiece W corresponding to the pressing ring 42 of this example, without changing the amount of polishing of the area w2 of the workpiece W (the area closer to the center than the area w3). As a result, it is possible to selectively press a predetermined area of ​​the workpiece W against the polishing pad 16 with an intended pressing force, and polish it to a desired shape according to the purpose.

[0065] The pressure state in the space 59 defined between the lower surface of the work guide 22 (guide top plate 22a) (and the second suspending member 28) and the upper surface of the swing plate 34 (and the third suspending member 38) may affect the load applied to each of the regions w1 to w4. Therefore, the pressure in the space 59 may be optimized depending on the polishing result. This allows each region to be pressed with a more intended pressing force, making it possible to more reliably and selectively change the polishing amount in each region. Specific configurations include, for example, a configuration in which the space 59 is sealed, a configuration in which the space 59 is open to the atmosphere, a configuration in which an openable communication passage (not shown) that connects the inside and outside of the space 59 is provided to allow selection between a sealed state and an open-to-the-atmosphere state, and a configuration in which the space 59 is configured as a pressure-adjustable fluid chamber (for example, a fourth fluid chamber (not shown) to which a fluid can be supplied via a fourth flow passage (not shown) connected to the pressure adjustment mechanism 96) to adjust the pressure in the space 59. In addition, in the polishing head 12 (polishing apparatus 10) equipped with a mechanical pressing mechanism using the oscillating plate 34 according to this embodiment, the load applied to each of the regions w1 to w4 can be suitably adjusted when the space 59 is open to the atmosphere, and it is preferable that at least the space 59 is configured to be open to the atmosphere.

[0066] As described above, according to the workpiece polishing apparatus of the present invention, when polishing a workpiece, the head base unit is lowered while the workpiece guide is in contact with the polishing pad. This transmits a pressing force from the head base unit to the swing plate via the shaft, allowing the swing plate to mechanically press the workpiece via the elastic sheet. Therefore, the swing plate can press areas (e.g., the periphery of the workpiece) that are difficult to press with sufficient pressure using a configuration that presses the entire workpiece with fluid pressure. This configuration allows for precise control of the pressing force by controlling the height position of the polishing head. Furthermore, it simplifies the configuration by eliminating the need for additional fluid chambers or separation walls. Furthermore, by lowering the head base unit while maintaining a vacuum (negative pressure) in the first fluid chamber, the holding plate can mechanically press the workpiece via the elastic sheet. Therefore, by appropriately setting the pressing positions of the swing plate and the holding plate, or by appropriately combining the pressing force due to fluid pressure and the mechanical pressing force by the swing plate and the holding plate, the workpiece can be polished to a desired shape according to the purpose.

[0067] Furthermore, according to the workpiece polishing method of this embodiment, the pressing force on the workpiece can be accurately controlled by controlling the height position of the polishing head (for example, by directly detecting it using a sensor, etc.) and further controlling the driving force and driving amount of the driving source that moves the polishing head up and down. As an example of such control, by limiting the range of motion of the head base part or the driving force or driving amount of the driving source to a required range, it is possible to prevent excessive pressing force from being applied to the workpiece.

[0068] The present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the present invention. For example, the dimensions of the work guide, retainer ring, holding plate, swing plate, and pressing ring can be set as desired. Therefore, as described above, a configuration is possible in which the pressing ring presses a portion other than the peripheral portion of the workpiece (for example, a portion closer to the center or a portion closer to the outer edge). Similarly, the third fluid chamber can be configured to press a portion other than the polishing pad in the outer region of the workpiece. [Explanation of symbols]

[0069] 10 Workpiece polishing device 12 Polishing head 14 Surface Plate 16 polishing pads 18 Head axis 20 Head base 22 Work Guide 24 First lifting member 28 Second lifting member 30 Second fluid chamber 34 Swing Plate 36 Retaining plate 42 Pressing ring 44 Elastic sheet body 46 1st fluid chamber 56 Third fluid chamber 59 Space 60 sensors 62 Control Unit 64 Drive unit 66 Vertical movement drive mechanism 68 Rotational drive mechanism 70 Linear motion device 72 Drive source 80 Current detector 81 Encoder 82 Power Source 96 Pressure adjustment mechanism 102 Support member double work

Claims

1. a surface plate having a polishing pad attached to its upper surface and rotating within a horizontal plane; a polishing head that is provided above the surface plate so as to be vertically movable and rotatable, and that holds a workpiece on its lower surface and rotates it while pressing it against the polishing pad to polish it; a head shaft fixed to an upper surface of the polishing head; a drive unit that moves the head shaft up and down and rotates the polishing head; a control unit that controls the drive unit, The polishing head includes: a head base portion having a base top plate to which the head shaft is fixed at the center of the upper surface, a ring-shaped side wall portion extending downward from the outer edge of the base top plate, and a shaft portion protruding from the center of the lower surface of the base top plate; a work guide located below the head base portion and movable up and down relative to the head base portion via a first suspending member; a swing plate located below the work guide and pivotally supported on the shaft portion so as to be swingable; a holding plate provided at the lower end of the shaft portion; an elastic sheet body that covers the lower side of the holding plate, is fixed to the work guide at its peripheral edge, holds the work on its lower surface, and presses the work; a first fluid chamber defined between the elastic sheet and the holding plate; a first flow path connected to a pressure adjustment mechanism that is driven and controlled by the control unit and that supplies fluid into the first fluid chamber; The control unit controls the drive unit to control the height position of the head base unit when polishing the workpiece, so that the workpiece can be mechanically pressed by the swing plate via the elastic sheet body. A workpiece polishing device characterized by the above.

2. a sensor for detecting a height position of the head base portion when the workpiece is polished; The control unit controls the driving of the drive unit so that the height position of the head base unit detected by the sensor is at a required height position.

2. The workpiece polishing apparatus according to claim 1, wherein:

3. The sensor is a length measuring sensor that detects the vertical distance between the head base portion and the work guide as the height position of the head base portion.

3. The workpiece polishing apparatus according to claim 2, wherein:

4. The sensor is a length measuring sensor that detects the vertical distance between the head base portion and the polishing pad as the height position of the head base portion.

3. The workpiece polishing apparatus according to claim 2, wherein:

5. the drive unit has a servo motor, which is driven and controlled by the control unit, as a vertical movement drive mechanism for moving the head shaft up and down; further comprising at least one of a current detector that detects a value of a current flowing through the servo motor and an encoder that detects a rotation speed or a rotation angle of the servo motor; The control unit controls the drive unit so that the detected value detected by the current detector or the encoder becomes a required value or is kept within a required range. The workpiece polishing device according to any one of claims 1 to 4, characterized in that

6. The vertical movement drive mechanism is configured to include a spline mechanism.

6. The workpiece polishing apparatus according to claim 5, wherein:

7. The swing plate is provided on its underside with a pressing ring that presses the workpiece via the elastic sheet. The workpiece polishing device according to any one of claims 1 to 6, characterized in that

8. The pressing ring is disposed at a position where it presses the peripheral edge of the workpiece.

8. The workpiece polishing apparatus according to claim 7, wherein:

9. The polishing head includes: a second fluid chamber defined between a lower surface of the head base portion and an upper surface of the work guide; a second flow path that supplies a fluid into the second fluid chamber, The work guide is provided on its lower surface with a retainer ring that abuts against the polishing pad in the outer region of the work when the work is polished. The workpiece polishing device according to any one of claims 1 to 8, characterized in that

10. A workpiece polishing method in which a workpiece is held on a polishing head, lowered while rotating, and pressed against a polishing pad from above to polish the workpiece, At least one of a driving force and a driving amount of a driving source of a vertical movement driving mechanism that moves the polishing head up and down; The height position of the polishing head during polishing of the workpiece is controlled by controlling the vertical distance between the polishing head and the polishing pad, thereby controlling the pressing force of the polishing head against the workpiece. A workpiece polishing method characterized by the above.

11. A workpiece polishing method in which a workpiece is held on a polishing head, lowered while rotating, and pressed against a polishing pad from above to polish the workpiece, At least one of a driving force and a driving amount of a driving source of a vertical movement driving mechanism that moves the polishing head up and down; The pressing force of the polishing head against the workpiece is controlled by controlling the height position of the polishing head during polishing of the workpiece by controlling the vertical distance between a head base portion of the polishing head that is connected to the vertical movement drive mechanism and moved up and down by the drive source, and a work guide that is provided below the head base portion and is vertically movable relative to the head base portion via a hanging member. A workpiece polishing method characterized by the above.

12. The vertical distance between the polishing head and the polishing pad is detected and controlled by a sensor. The method for polishing a workpiece according to claim 10, characterized in that

13. The vertical distance between the head base portion and the work guide is detected and controlled by a sensor. The method for polishing a workpiece according to claim 11, characterized in that

14. The drive source is a servo motor, The driving force of the driving source is controlled as the rotational force of the servo motor, and the driving amount of the driving source is controlled as the number of rotations or the rotation angle of the servo motor. The workpiece polishing method according to any one of claims 10 to 13, characterized in that

15. Limiting the driving force or the driving amount of the driving source to a required range so that the load applied to the workpiece is kept within the required range. The workpiece polishing method according to any one of claims 10 to 14, characterized in that

16. The range of motion of the head base portion is limited to a required range so that the load applied to the workpiece is kept within a required range.

14. The method for polishing a workpiece according to claim 11 or 13, wherein:

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