JP7807791B2 - Workpiece polishing device and workpiece polishing method - Google Patents

Description

The present invention relates to a workpiece polishing device and a workpiece polishing method.

A workpiece polishing device is known that polishes a workpiece by pressing a workpiece held on the underside of a polishing head installed above a surface plate against a polishing pad attached to the top surface of the surface plate and moving the surface plate and polishing head relative to each other (Patent Document 1: JP 2010-240767 A).

In the workpiece polishing device illustrated 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 that it can move up and down, and a fluid chamber is defined between the head member and the holding plate. Fluid is supplied into the fluid chamber, pressurizing it, pushing the holding plate downward, and the workpiece held on the underside of the holding plate is pressed against the surface plate (polishing surface) and polished.

JP 2010-240767 A

As exemplified by Patent Document 1, in a workpiece polishing device that pressurizes the fluid chamber to pressurize the 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 area of the workpiece is generally weaker than that applied to the center. To address this issue, a configuration could be considered in which the fluid chamber is divided into multiple sections and the pressing force is controlled for each specified area of the workpiece. However, this configuration poses the problem of being complicated. Furthermore, separating the fluid chambers with partitions 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 uses a simple configuration and can press any area of the workpiece with the intended pressing force.

The present invention was made in consideration of the above circumstances, and aims to provide a workpiece polishing device and workpiece polishing method with a simple configuration that can press a workpiece against a polishing pad with the intended pressing force, thereby polishing it into a desired shape according to the purpose.

The present invention solves the above problem by the solution described below as one embodiment.

The workpiece polishing device of 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 that is vertically movable and rotatable above the surface plate, holding a workpiece on its lower surface and pressing it against the polishing pad while rotating it, polishing it; a head shaft fixed to the upper surface of the polishing head; a drive unit that moves the head shaft up and down and rotates the polishing head; and a control unit that drives and controls the drive unit. 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 vertically movable relative to the head base portion via a first suspension member. the workpiece polishing head includes a work guide, a swinging plate positioned below the work guide and swingably supported on the shaft, a holding plate attached to the lower end of the shaft, an elastic sheet fixed to the work guide at its peripheral edge so as to cover the bottom of the holding plate, holding the workpiece on its underside and pressing against the workpiece, a first fluid chamber defined between the elastic sheet 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; the control unit controls the drive unit to control the height position of the head base unit during polishing of the workpiece, thereby enabling the swinging plate to mechanically press against the workpiece via the elastic sheet.

Note that "during polishing" here means "after the work guide comes into contact with the polishing pad."

When polishing a workpiece, the head base is lowered with the workpiece guide in contact with the polishing pad. This transmits the pressing force from the head base via the shaft to the oscillating plate, which then mechanically presses the workpiece via the elastic sheet. This allows the oscillating plate to press areas (such as the periphery 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 allows for precise control of pressing force by controlling the height position of the polishing head, and also simplifies the configuration by eliminating the need for unnecessary fluid chambers or separation by partitions, etc.

In addition, by lowering the head base while creating a vacuum (negative pressure) inside the first fluid chamber, the workpiece W can be mechanically pressed by the holding plate via the elastic sheet. Therefore, by appropriately setting the pressing positions of the oscillating plate and holding plate, or by appropriately combining the pressing force of the fluid pressure with the mechanical pressing force of the oscillating plate and holding plate, the workpiece can be polished to the desired shape depending on the purpose. Furthermore, the oscillating plate oscillates when it contacts the workpiece via the elastic sheet, maintaining its contact surface parallel to the workpiece at all times, allowing the workpiece to be pressed with an even pressure. This makes it possible to polish a specified portion of the workpiece stably and reliably.

It is also preferable to further include a sensor that detects the height position of the head base unit when the workpiece is being polished, and the control unit controls the drive of 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, when polishing the workpiece, the height position of the lowered head base unit is directly detected and controlled by the sensor, 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 being polished, it is possible to minimize the effects of dimensional errors and assembly errors of the polishing head and the various components related to its up-and-down movement drive mechanism, thereby enabling accurate positioning. This makes it possible to more accurately control the pressing force applied to the workpiece by the swing plate and holding plate.

The sensor can 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 can 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.

Furthermore, the drive unit preferably has a servo motor controlled by the control unit as a vertical movement drive mechanism for moving the head shaft up and down, and further includes at least one of a current detector that detects the value of the current flowing through the servo motor and an encoder that detects the rotation speed or rotation angle of the servo motor, and the control unit preferably controls the drive unit so that the value detected by the current detector or encoder becomes a required value or is kept within a required range. This makes it possible to more accurately control the pressing force applied to the workpiece by the swing plate and holding plate by directly detecting and controlling the height position of the polishing head with a sensor, while also controlling the driving force and driving amount of the drive source that moves the polishing head up and down.

It is also preferable that the vertical movement drive mechanism is configured with a spline mechanism. A servo mechanism equipped with a spline mechanism can move the head shaft up and down with high precision, making it possible to more accurately position the polishing head (head base portion) at the desired position.

It is also preferable that the oscillating plate be provided with a pressing ring on its underside that presses against the workpiece via the elastic sheet. This allows the pressing force of the oscillating plate to be transmitted to the pressing ring, which then presses against the workpiece via the elastic sheet. Therefore, the pressing area of the oscillating plate can be easily and freely set by adjusting the position of the pressing ring (mounting position on the underside of the oscillating plate), ensuring that a predetermined area of the workpiece or a predetermined area of the polishing pad outside the workpiece is pressed with the intended pressing force.

The pressing ring is preferably positioned so that it presses against the peripheral edge of the workpiece. This makes it possible to reliably press the peripheral edge of the workpiece with the intended pressing force, which is difficult to achieve with a configuration that presses the entire workpiece using fluid pressure.

The polishing head also preferably has 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 on 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 recess, and the edge of the workpiece comes into contact with the peripheral wall of the recess, making it more likely to be over-polished. In response, the retainer ring presses the polishing pad on the outer region of the workpiece so that it is approximately flush with the workpiece's polished surface, preventing over-polishing of the edge of the workpiece. Furthermore, by adjusting the pressing force of the retainer ring, the tension of the elastic sheet body can be changed, thereby affecting the polished shape of the workpiece W.

In addition, the workpiece polishing method of the present invention is a method of polishing a workpiece in which a polishing head holds the 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 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 the polishing head and the polishing pad. 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.

Note that "during polishing" here means "after the work guide comes into contact with the polishing pad."

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

This invention uses a simple configuration to press the workpiece against the polishing pad with the intended pressure, allowing it to be polished to the desired shape for the intended purpose.

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. 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. 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. 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. 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. 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.

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

Figure 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 underside with the surface Wa to be polished facing downward, and polishes the workpiece W by pressing it against a polishing pad 16 on the top surface of a surface plate 14 that rotates in a horizontal plane.

Reference numeral 20 denotes the head base portion 20, which includes a base top plate 20a, a ring-shaped side wall 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 underside of the base top plate 20a. A head shaft 18 extending upward is fixed to the center of the top 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, centered on 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.

Next, located below the head base portion 20 is a work guide 22 having 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 polishing the workpiece W, the work guide 22 surrounds the workpiece W with the retainer ring 22c, holding the workpiece W against the underside of an elastic sheet body 44 (described below).

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

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, 28 are both formed from diaphragms made of 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, 28. Furthermore, 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, 28, causing the work guide 22 to rotate. The first and second suspending members 24, 28 may be configured in any manner or made of any material, as long as they can suspend the work guide 22 so that it can move up and down, as described above. 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.

A second fluid chamber 30 is defined between the underside of the head base portion 20 (base top plate 20a) and the upper surface of the work guide 22 (and the first and second suspension members 24, 28). 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 positive pressure to be applied to the second fluid chamber 30 to press the work guide 22 downward, or negative pressure to lift the work guide 22 upward. This allows the pressure applied to the retainer ring 22c to be increased or decreased. Therefore, the retainer ring 22c can press the polishing pad 16, which forms 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; the fluid may be water, oil, or the like. Note that the second fluid chamber 30 is not an essential component of the present application, but if the second fluid chamber 30 is provided, the first and second suspending 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.

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. The swing mechanism 40 may, for example, be a spherical bearing. The swing plate 34 is also swingably connected to the work guide 22 on its outer periphery via a third suspension member 38. This defines a third fluid chamber 56, which will be described later. However, since the third fluid chamber 56 is not a required component in this application, the third suspension member 38 is not necessarily provided. Here, the third suspension member 38 is formed from a rubber diaphragm, similar to the first and second suspension 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.

A downwardly protruding pressing ring 42 is provided on the underside of the oscillating plate 34. When polishing the workpiece W, the pressing force from the lowered head base portion 20 is transmitted via the shaft portion 20c to the oscillating plate 34 and then to the pressing ring 42, mechanically pressing the workpiece W via the elastic sheet 44. However, since the pressing ring 42 is not a required component in this application, the workpiece W may also be pressed by the oscillating plate 34. Meanwhile, the shape, size, and placement (mounting position on the underside of the oscillating plate 34) of the pressing ring 42 are not limited. Therefore, the pressing ring 42 allows the pressing area of the oscillating plate 34 to be easily and freely set, enabling mechanical pressing of a predetermined area of the workpiece W. The pressing ring 42 in 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 it may also be configured to press a specific area on the polishing pad 16. Furthermore, it is preferable that the pressing ring 42 be made of a material that can act as a cushioning material, such as rubber.

Next, a holding plate 36 is fixed to the lower end of the shaft portion 20c. Furthermore, an elastic sheet 44 has its peripheral edge 44a fixed to the work guide 22 (the lower surface of the pressure 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 pressure ring portion 22b, sandwiching the elastic sheet 44. The elastic sheet 44 is formed, for example, from a flexible resin material such as PET (polyethylene terephthalate). However, it may also be formed from other materials.

A first fluid chamber 46 is defined between the elastic sheet 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 piping 21 or the like provided within the shaft portion 20c. By creating a vacuum (negative pressure) within the first fluid chamber 46, the workpiece W can be adsorbed and held against the underside of the elastic sheet 44. This allows the workpiece W to be picked up, or the holding plate 36 to mechanically press the workpiece W via the elastic sheet 44 when polishing the workpiece W. Alternatively, 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 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; the fluid may be water, oil, or the like. As shown in FIG. 1, when 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 rubber diaphragm, like the first, second, and third suspending members 24, 28, and 38, but its configuration and material are not limited.

A third fluid chamber 56 is defined between the outer periphery of the oscillating 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 the pressure adjustment mechanism 96. Meanwhile, the third fluid chamber 56 is connected to the first fluid chamber 46 via a communication path (not shown), which can be opened and 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 a required component in this application, when the third fluid chamber 56 is provided and pressurized, the fluid pressure can pressurize the inner edge of the retainer ring 22c 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 this configuration is not limited to this, and the fluid may be, for example, water, oil, etc.

A sensor 60 is provided on the exterior of 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 (e.g., the vertical distance between the lower end of the side wall portion 20b of the head base portion 20 and the shoulder (edge) 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 (e.g., 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 that drives and controls the drive unit 64 (servo motor 72, described below) 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, thereby adjusting the height position of the polishing head 12, so that the distance X (height position of the head base unit 20) detected by the sensor 60 becomes the required distance (height position).

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 height position of the polishing head is adjusted by detecting and adjusting the vertical distance from the support member (distance measuring sensor) to the polishing head's vertical movement drive mechanism, which is provided further above, and the vertical distance to the polishing pad below (not shown). With this configuration, the height position of the polishing head is detected and controlled from a position above the polishing head that is far away from the workpiece. Therefore, errors in the position adjustment of the polishing head occur due to dimensional errors and assembly errors of the various components 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.

In contrast, the configuration of the sensor 60 according to this embodiment 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. This minimizes the effects of dimensional errors and assembly errors of the components related to the polishing head 12 and its vertical movement drive mechanism 66, allowing the polishing head 12 to be accurately positioned at the required height. The sensor 60 may be a known length measurement sensor, such as an ultrasonic or laser type.

The position of the sensor 60 is not limited, and it may be located at any position where the distance X or the distance Y can be detected. The number of sensors 60 is also not limited. As shown in FIG. 3, in a polishing apparatus 10 having multiple polishing heads 12 and surface plates 14, a sensor 60 may be provided for each polishing head 12. Alternatively, a sensor 60 may be provided for only one polishing head 12, the detection value of that polishing head 12 is recorded, and the position of the other polishing heads 12 may be adjusted based on this detection 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, performing the specified polishing on each plate. Therefore, a sensor 60 may be provided for each surface plate 14 to detect the height position of each polishing head 12 on each surface plate 14, or a sensor 60 may be provided for only one surface plate 14, the detection values of each polishing head 12 that moves sequentially on that surface plate 14 recorded, and the position of each polishing head 12 on the other surface plates 14 adjusted based on these detection values. 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 to be polished. Therefore, even if sensors 60 are not provided for all polishing heads 12 or surface plates 14, the height position can be positioned relatively accurately at the required position with little influence from dimensional errors or assembly errors of each polishing head 12.

Next, the drive unit 64 of the polishing head 12 will be described. Figure 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 it by moving the head shaft 18 up and down. The drive unit 64 includes a vertical movement drive mechanism 66 and a rotation drive mechanism 68.

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 the spline shaft 70a, which is spline-engaged with the spline outer cylinder portion 70b, is threaded onto a ball screw shaft (not shown). The ball screw shaft is driven by the servo motor 72 via a timing belt or gear mechanism (not shown), thereby driving the spline shaft 70a vertically. The spline outer cylinder 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 connection portion 78 so as to be rotatable about its axis. As shown in FIG. 2, a current detector 80 is provided to detect the value of the current flowing through the servo motor 72. The current detector 80 is connected to the control unit 62, which controls the torque of the servo motor 72 in accordance with the information (detected value) from the current detector 80. Details will be described later.

The rotary drive mechanism 68 includes a drive source 82 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 includes a rotating unit 88 that rotates 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, while 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.

The vertical movement drive mechanism 66 and the rotary drive mechanism 68 may be configured in any way to move the head shaft 18 up and down and rotate it. As an example, the vertical movement drive mechanism 66 may be a linear motor or the like, which integrates the drive source 72 and the linear motion device 70, or a linear motor actuator or the like, which also integrates a guide mechanism for the linear motion device 70. In this case, the rotary drive mechanism 68 may directly rotate the head shaft 18 using a spindle or the like, or a linear motor actuator or the like with a built-in rotary drive mechanism 68 may be used (both not shown). As a variation 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 the guide mechanism for the linear motion device 70, and a spindle or the like may be provided as the rotary drive mechanism 68, with the guide mechanism and the rotary drive mechanism 68 being configured separately (both not shown). However, as in this embodiment, by configuring the vertical movement drive mechanism 66 with spline mechanisms 70 and 89 (including ball spline mechanisms and rotary ball spline mechanisms), it is possible to achieve highly accurate and precise positioning of the head shaft 18 relative to its height.

As shown in FIG. 2, the head shaft 18 is hollow, with a pipe 93 passing through it. The upper end of the pipe 93 is connected to a rotary joint 94, which is connected via a pipe 95 to a pressure adjustment mechanism 96 having a fluid supply source (not shown). The pipe 93 in the head shaft 18 is connected to each fluid chamber 30, 46, 56 in the polishing head 12, thereby forming first, second, and third flow paths 32, 48, 58 that connect the pressure adjustment mechanism 96 to each fluid chamber 30, 46, 56, allowing compressed air to be supplied to each fluid chamber 30, 46, 56 (see FIGS. 1 and 2). For ease of visualization, in FIG. 1, the second and third flow paths 32, 58, other than the first flow path 48, are shown with arrows leading directly from outside the polishing head 12 to each fluid chamber 30, 56, without passing through the pipe 93. The pressure adjustment mechanism 96 is connected to the control unit 62, allowing the pressure in each fluid chamber 30, 46, and 56 to be adjusted.

Next, the surface plate 14 is formed into a disk shape in a plan view (see Figure 3), with a polishing pad 16 affixed to its upper surface. The surface plate 14 is provided with a rotation drive mechanism (not shown) and is configured to be rotatable around an axis in a horizontal plane. It also has a slurry supply unit (not shown) that supplies polishing slurry onto the polishing pad 16. Therefore, when polishing the workpiece W, slurry is supplied to the workpiece W, and the polishing head 12 and 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 also be made of other materials.

Next, the arrangement of the polishing heads 12 and surface plates 14 will be described. There are no limitations on the arrangement of the polishing heads 12 and surface plates 14 in the polishing apparatus 10 of the present application, and there are no limitations on the number of polishing heads 12 and surface plates 14. However, as an example, they can be arranged as follows:

FIG. 3 is an explanatory diagram showing an example of the arrangement of the polishing heads 12 and is a schematic diagram (plan view) illustrating an example of a polishing apparatus 10 according to this embodiment. In this embodiment, the polishing apparatus 10 includes a base 98 on which a temporary stage 100, on which the workpiece W is loaded and unloaded, and multiple (three in this embodiment) surface plates 14 are radially arranged. 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 can move up and down independently and rotate independently. The axes 102a of the temporary stage 100 and the surface plates 14 are aligned. The support members 102 each have a rotation drive mechanism (not shown) and are configured to be rotatable (including intermittent forward and reverse rotation) about the axis 102a. This allows the polishing head 12 to revolve (including intermittently revolving in forward and reverse directions) around the axis 102a by rotating the support member 102.

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 removes (loads) the workpiece W placed on the temporary table 100, then moves sequentially to each surface plate 14 to perform the desired 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 processes. The direction and order of movement (rotation) of the polishing head 12 are not limited in any way. Furthermore, the number of surface plates 14 and polishing heads 12 is not limited, and the number of surface plates 14 and polishing heads 12 does not have to match. 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.

Next, the workpiece polishing method according to this embodiment will be explained using the workpiece polishing device 10 according to this embodiment as an example.

(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 polishing head 12 is lowered by the drive unit 64. When the retainer ring 22c provided 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 with fluid pressure through the elastic sheet 44, and slurry is supplied to the workpiece W. At the same time, the surface plate 14 and the 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 on the workpiece W can be adjusted, and the polished shape of the workpiece W can be affected.

(Pressing of 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). Furthermore, 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. Meanwhile, 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). Furthermore, 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 even more strongly.

(Pressing of the peripheral portion 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 swing plate 34 is lowered via the head base unit 20 (shaft 20c). Then, the pressing ring 42 provided on the underside of the swing plate 34 comes into contact with the peripheral edge of the workpiece W via the elastic sheet 44, and the pressing force from the head base unit 20 is transmitted to the swing 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 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 the chambers by partitions or the like.

In addition, this mechanism moves the head base portion 20 up and down (adjusts the height position) while the work guide 22 (retainer ring 22c) is in contact with the polishing pad 16 and its height position is determined, and the pressing ring 42 of the swing plate 34 presses the peripheral edge of the workpiece W via the elastic sheet body 44. Therefore, the pressing of the peripheral edge 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).

In addition, with this mechanism, when the pressing ring 42 contacts the workpiece W, the oscillating plate 34 oscillates, 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 an even pressing force. Furthermore, the vertical movement of the polishing head 12 (head base portion 20) is precisely position-controlled via spline mechanisms 70 and 89 by a 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 the desired shape.

(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 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 portion 20, from which the "distance in the vertical direction between the work guide 22, whose height position is fixed, and the head base portion 20, which moves up and down" or the "distance in the vertical direction between the polishing pad 16 and the head base portion 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.

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. This minimizes the effects of dimensional errors and assembly errors of the components related to the polishing head 12 and its vertical movement drive mechanism 66, and the servo mechanism can move the head shaft 18 up and down with high precision, 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 pressure, allowing it to be polished to the desired shape according to the purpose.

Furthermore, when polishing the workpiece W, even when the polishing head 12 is not moving up and down, the polishing pad 16 may sink downward under pressure, causing changes in 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 the height position of the polishing head 12 and the air pressure in the first fluid chamber 46 and the second fluid chamber 30 can be adjusted to appropriately optimize 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).

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 with a limiter function that limits the range of motion of the head base unit 20. This prevents the head base unit 20 from being positioned too high, preventing the required load from being applied to the workpiece W, or conversely, preventing it from being positioned too low, preventing excessive load from being applied to the workpiece W. As a result, the workpiece W can be polished with the optimal pressing force, further improving polishing quality.

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 is a desired value or is kept within a desired range. This allows for more accurate control of the pressing force on the workpiece W by directly detecting and controlling the height position of the polishing head 12 using the sensor 60 and further controlling the driving force of the driving source 72 that moves the polishing head 12 up and down. 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.

Furthermore, an encoder 81 that detects the rotation speed or rotation angle of the servo motor 72 may be provided in addition to or instead of the current detector 80. 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 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, along with the sensor 60 (neither is shown).

Figures 4 and 5 are photographs showing the load distribution on a circular workpiece W when the workpiece W is pressed under specified 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 approaches red from blue, but 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. Figure 4-I shows the state in which the polishing head 12 has been lowered and the retainer ring 22c has been brought into contact with the polishing pad 16, which is the outer region of the workpiece W (indicated by symbol w1). Figure 4-II shows the state in which the first fluid chamber 46 has been positively pressurized and the workpiece W has been pressed by fluid pressure via the elastic sheet 44. The workpiece W area is indicated by symbol w2. FIG. 4-III shows the state in which the polishing head 12 is then further lowered, causing the retaining ring 22c to contact the polishing pad 16, lowering the head base 20 and the swing plate 34 via the shaft 20c, causing the pressing ring 42 to press against the peripheral edge of the workpiece W (indicated by symbol w3) 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, causing the fluid pressure to press against the inner edge of the retaining ring 22c (indicated by symbol w4) 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.

Figure 5 also shows the following polishing conditions: the polishing head 12 is lowered with the retainer ring 22c abutting against 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 against region w1 via the elastic sheet 44; a constant positive pressure is applied within the first fluid chamber 46 to press against 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 against the peripheral edge w3 of the workpiece W via the elastic sheet 44 with a constant pressing force, closing the communication passage between the first fluid chamber 46 and the third fluid chamber 56; and the third fluid chamber 56 is open to the atmosphere. Figure 5 shows photographs illustrating 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 conditions. In addition to the above w1, w2, and w3, the photograph also shows the inner edge w4 of the retainer ring 22c, which corresponds to the third fluid chamber 56.

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. Figure 5-III shows the polishing head 12 at a height of -0.4 mm from the reference. Figure 5-IV shows the polishing head 12 at a height of -0.6 mm from the reference. 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. Furthermore, 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 increased. 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.

Figure 6 is a graph showing the amount of polishing for each workpiece W under the polishing conditions shown in Figure 5 above. 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 since only relative changes are required, units and scale values are omitted. As shown in Figure 6, the amount of polishing for the workpiece W generally showed a very gentle decline 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 position of the pressure ring 42 was lowered by 0.2 mm, the amount of polishing increased toward the outer periphery, and the amount of polishing increased more steeply with each 0.2 mm decrease. In this way, by changing the pressing force of the pressure ring 42, it is possible to selectively change the amount of polishing of the peripheral portion w3 of the workpiece W, which corresponds to the pressure ring 42 in this example, without changing the amount of polishing of the workpiece W area w2 (the area closer to the center than area w3). This makes it possible to selectively press a specific area of the workpiece W against the polishing pad 16 with the intended pressing force and polish it to the desired shape depending on the purpose.

In addition, since the pressure state in space 59 defined between the underside (and second suspension member 28) of work guide 22 (guide top plate 22a) and the upper surface (and third suspension member 38) of oscillating plate 34 may affect the load applied to each of regions w1 to w4, the pressure in space 59 may be configured to be optimal 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 amount of polishing in each region. Specific configurations include, for example, a configuration in which space 59 is sealed, a configuration in which space 59 is open to the atmosphere, a configuration in which an openable communication passage (not shown) is provided connecting the inside and outside of space 59 so that the sealed state and the open-to-the-atmosphere state can be selected, and a configuration in which space 59 is configured as a pressure-adjustable fluid chamber (e.g., a fourth fluid chamber (not shown) to which fluid can be supplied via a fourth flow passage (not shown) connected to pressure adjustment mechanism 96) so that the pressure in space 59 can be adjusted. In addition, in the polishing head 12 (polishing apparatus 10) equipped with a mechanical pressing mechanism using the swing plate 34 according to this embodiment, the load applied to each of the areas 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 be configured to be open to the atmosphere.

As described above, with the workpiece polishing device according to 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 the pressing force from the head base unit to the oscillating plate via the shaft, allowing the oscillating plate to mechanically press the workpiece via the elastic sheet. Therefore, the oscillating plate can press areas (e.g., the periphery of the workpiece) where sufficient pressing force is difficult to achieve with a configuration that presses the entire workpiece using fluid pressure. This configuration allows for precise control of the pressing force by controlling the height position of the polishing head. It also simplifies the configuration by eliminating the need for unnecessary fluid chambers or separation walls, etc. Furthermore, by lowering the head base unit while maintaining a vacuum (negative pressure) inside 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 oscillating plate and holding plate, and by appropriately combining the pressing force due to fluid pressure and the mechanical pressing force of the oscillating plate and holding plate, the workpiece can be polished to a desired shape according to the purpose.

Furthermore, with the workpiece polishing method according to this embodiment, it is possible to accurately control the pressing force on the workpiece 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 drive source that moves the polishing head up and down. As an example of such control, excessive pressing force can be prevented from being applied to the workpiece by limiting the range of motion of the head base unit and the driving force or driving amount of the drive source to a required range.

The present invention is not limited to the above-described embodiments, and various modifications are possible 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, it is possible to configure the pressing ring to press against a portion of the workpiece other than its peripheral edge (for example, a portion closer to the center or a more outer edge portion). Similarly, the third fluid chamber can be configured to press against a portion of the workpiece outside the polishing pad.

10 Workpiece polishing device 12 Polishing head 14 Surface plate 16 Polishing pad 18 Head shaft 20 Head base portion 22 Workpiece guide 24 First suspending member 28 Second suspending member 30 Second fluid chamber 34 Swing plate 36 Holding plate 42 Pressing ring 44 Elastic sheet body 46 First fluid chamber 56 Third fluid chamber 59 Space 60 Sensor 62 Control unit 64 Drive unit 66 Up-down movement drive mechanism 68 Rotation drive mechanism 70 Linear motion device 72 Drive source 80 Current detector 81 Encoder 82 Drive source 96 Pressure adjustment mechanism 102 Support member W Workpiece

Claims (16)

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 movable up and down 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;
A workpiece polishing device characterized in that the control unit controls the drive unit to control the height position of the head base unit when polishing the workpiece, thereby enabling the oscillating plate to mechanically press the workpiece through the elastic sheet body. a sensor for detecting a height position of the head base portion when the workpiece is polished;
2. The workpiece polishing apparatus according to claim 1, wherein the control unit controls the drive unit so that the height position of the head base unit detected by the sensor is at a required height position. 3. The workpiece polishing device according to claim 2, wherein the sensor is a length measuring sensor that detects the vertical distance between the head base portion and the workpiece guide as the height position of the head base portion. 3. The workpiece polishing device according to claim 2, wherein 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. 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;
A workpiece polishing apparatus as described in any one of claims 1 to 4, characterized in that the control unit controls the drive unit so that the detection value detected by the current detector or the encoder becomes a required value or is kept within a required range. 6. A workpiece polishing apparatus according to claim 5, wherein the vertical movement drive mechanism is configured to include a spline mechanism. 7. The workpiece polishing apparatus according to claim 1, wherein the swinging plate is provided on its underside with a pressing ring that presses the workpiece via the elastic sheet body. 8. The workpiece polishing apparatus according to claim 7, wherein the pressing ring is disposed at a position where it presses against the peripheral edge of the workpiece. 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,
A workpiece polishing apparatus as described in any one of claims 1 to 8, characterized in that the workpiece guide has a retainer ring on its underside that abuts against the polishing pad in the outer region of the workpiece when the workpiece is polished. 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;
A workpiece polishing method characterized by controlling the pressing force of the polishing head against the workpiece by controlling the height position of the polishing head during polishing of the workpiece by controlling the vertical distance between the polishing head and the polishing pad . 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;
A workpiece polishing method characterized by controlling the pressing force of the polishing head against the workpiece by controlling the height position of the polishing head during polishing of the workpiece by controlling the vertical distance between a head base portion in the polishing head that is connected to the vertical movement drive mechanism and moved up and down by the drive source, and a workpiece guide that is arranged below the head base portion and can move up and down relative to the head base portion via a hanging member. 11. A method for polishing a workpiece according to claim 10 , wherein the vertical distance between the polishing head and the polishing pad is detected and controlled by a sensor. 12. A workpiece polishing method according to claim 11 , wherein the vertical distance between said head base portion and said workpiece guide is detected and controlled by a sensor. The drive source is a servo motor,
The workpiece polishing method according to any one of claims 10 to 13 , characterized in that the driving force of the drive source is controlled as the rotational force of the servo motor, and the driving amount of the drive source is controlled as the rotation speed or rotation angle of the servo motor. A workpiece polishing method according to any one of claims 10 to 14 , characterized in that the driving force or the driving amount of the driving source is limited to a required range so that the load applied to the workpiece is kept within a required range. 14. A workpiece polishing method according to claim 11 or 13 , wherein 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.