JP2010172988A - Pressing force detecting device of polishing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressing force detecting device capable of exactly detecting a pressing force acting on a polishing part. <P>SOLUTION: A drive shaft 30 of a polishing head is rotatably movably supported in a rotating axis direction at a support frame 23 and driven by a head rotating mechanism 40 and a head elevating/lowering mechanism 50. The drive shaft 30 and the polishing head 70 are elastically, relatively connected so as to be displaceable in a rotating axis direction by a coupling part 60, and a relative and displacement detection part 110 for detecting the relative displacement of the drive shaft 30 and the polishing head 70 in a non-contact manner is arranged at the coupling part 60. A calculation processing device 120 calculates a polishing load based on the detected relative displacement amount and an elastic modulus of the coupling part 60. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pressing force detecting device that detects a pressing force of a polishing pad against a polishing object in a polishing apparatus that rotates a polishing pad and presses the polishing object to perform polishing.

  2. Description of the Related Art As a polishing apparatus provided with a pressing force detection apparatus as described above, a CMP (Chemical Mechanical Polish) apparatus is known that performs chemical mechanical polishing on a polishing target such as a glass substrate, a quartz substrate, or a semiconductor wafer in a flat manner. There are various types of CMP apparatuses. For example, a drive shaft is supported by a polishing arm provided opposite to a work holding unit that holds an object to be polished so that the drive shaft can rotate and move in the direction of the rotation axis. It is driven by a rotating mechanism and a shaft moving mechanism provided inside, and a polishing head connected to the shaft end of the drive shaft is rotated, and a polishing pad is pressed against the object to be polished while supplying slurry to perform polishing. Configured as follows.

  In such a polishing apparatus, an air cylinder is widely used as an actuator of an axis moving mechanism that moves a drive shaft in the direction of the rotation axis and presses a polishing pad against an object to be polished. In such a CMP apparatus, the pressure detection device for detecting the pressure (polishing load, polishing pressure) of the polishing pad against the object to be polished detects the pressure of the air supplied to the cylinder chamber of the air cylinder by the pressure detector. Then, it is configured to calculate from the detected internal pressure of the cylinder chamber and the known pressure receiving area of the piston. Alternatively, a detector for detecting a load or strain is provided at the connecting portion that connects the piston rod and the drive shaft, and the pressing force of the polishing pad against the object to be polished is calculated from the load or strain detected by the detector. (For example, refer to Patent Document 1 and Patent Document 2).

JP 2002-254305 A JP 2004-319730 A

  However, in the conventional pressing force detection device as described above, the detection value detected by the detector includes the friction resistance generated in the piston or piston rod seal portion of the air cylinder and the ball bearing that rotatably supports the drive shaft. Includes rolling resistance, rolling resistance of a ball spline that supports the drive shaft so as to be movable in the direction of the rotation axis, and an error occurs between the pressing force actually acting between the polishing pad and the object to be polished. There was a problem. Furthermore, these resistances change in a complicated manner depending on the rotational speed and moving speed of the drive shaft, the temperature, the lubrication state of each part, etc., and thus it was difficult to unambiguously correct them.

  The present invention has been made in view of the above problems, and provides a pressing force detection device capable of more accurately detecting a pressing force acting between a polishing pad and an object to be polished, that is, a polishing processing portion. With the goal.

  In order to achieve the above object, the present invention provides a drive shaft disposed on a base (for example, the support frame 23 in the embodiment) so as to be rotatable and movable in the direction of the rotation axis, and a coupling portion on the drive shaft. A polishing pad mounted on the polishing head by rotating the drive shaft and moving it in the direction of the rotation axis. A pressing force detection device of a polishing apparatus configured to perform a polishing process by pressing a workpiece against a polishing object held by a workpiece holding unit. In addition, the coupling unit is configured to integrally rotate the drive shaft and the polishing head in the rotation direction of the drive shaft, and to connect the drive shaft and the polishing head in an elastically displaceable manner in the rotation axis direction. And a relative displacement detection means (for example, the relative displacement detection unit 110 in the embodiment) that detects the relative displacement amount of the drive shaft and the polishing head in the rotational axis direction in the coupling unit in a non-contact manner, and a preset cup. An arithmetic processing unit that calculates the pressing force of the polishing pad against the object to be polished based on the elastic coefficient of the ring part and the relative displacement amount of the drive shaft and the polishing head detected by the relative displacement detection means. Thus, a pressing force detection device of the polishing apparatus is configured.

  In the coupling portion, the drive shaft and the polishing head are preferably connected by a plurality of leaf springs (parallel leaf springs) extending in a direction orthogonal to the rotation shaft and provided in parallel.

  Further, the relative displacement detection means includes a first reflecting surface disposed in parallel at the same inclination angle on an axial plane including a rotating shaft provided on a driving shaft and a facing portion of the polishing head facing each other in the coupling portion. A light source that illuminates the first reflecting member by emitting probe light that is provided on the base and located on the outer peripheral side of the opposing portion, and is orthogonal to the rotation axis in the axial plane; And a position detector that is provided on the opposite side of the light source across the rotation axis and receives the reflected light that is emitted when the probe light is reflected by the first reflecting member and the second reflecting member and detects the position of the reflected light. The arithmetic processing unit calculates a relative displacement amount in the rotation axis direction between the drive shaft and the polishing head from a change in the position of the reflected light input from the position detector, and the calculated relative displacement amount is set in advance. Cup It is preferable to calculate the pressing force of the polishing pad for polishing the object based on the elastic modulus of the grayed portion.

  In this case, the coupling portion includes a bottomed cylindrical outer cylinder portion provided on the drive shaft so as to extend in the rotation axis direction, and a polishing head provided on the polishing head so as to extend in the rotation axis direction. And a plurality of leaf springs extending in a direction orthogonal to the rotation axis in the outer tube portion and connecting the outer tube portion and the head shaft, and the first reflecting member and the second reflecting member are Is provided at the bottom of the outer cylinder, the other is provided at the shaft end of the head shaft facing the bottom, and the peripheral surface of the outer cylinder where the reflecting surface of the first reflecting member is oriented is emitted from the light source. A light introduction part for introducing the probe light into the first reflection member in the outer cylinder part is formed, and the reflection surface of the second reflection member is oriented on the peripheral surface of the outer cylinder part and is reflected by the first reflection member and the second reflection member. It is preferable that a light deriving portion for deriving the reflected light from the outer tube portion is formed.

  According to the present invention, when the drive shaft is rotated and moved in the direction of the rotation axis and the polishing pad is pressed against the object to be polished, the drive shaft and the polishing head are elastically displaced relative to each other according to the pressing force at this time. To do. This relative displacement amount is detected by a non-contact relative displacement detection means, and the pressing force is calculated by the arithmetic processing unit based on the detected relative displacement amount and the elastic coefficient of the coupling portion. For this reason, the calculated pressing force does not include the frictional resistance of the actuator that moves the drive shaft in the direction of the rotation axis, the rolling resistance of ball bearings, ball splines, etc. that support the drive shaft, and is caused by these resistances Errors can be eliminated. Therefore, it is possible to provide a pressing force detection device that can detect the pressing force acting on the polishing portion more accurately.

  In addition, according to the configuration in which the drive shaft and the polishing head are connected by the parallel leaf spring extending in the direction orthogonal to the rotation axis in the coupling portion, friction resistance and rolling resistance may be generated in the connection portion between the drive shaft and the polishing head. Therefore, the detection accuracy of the pressing force can be further improved. Moreover, according to the structure which provided the 1st, 2nd reflection member in the opposing part of a drive shaft and a grinding | polishing head, and provided the light source and the position detector in the base side, an electronic component, an electrical wiring, etc. are provided in the rotary body side. Therefore, it is possible to provide a pressing force detection device with a simple structure and high long-term reliability.

It is a schematic block diagram of the pressing force detection apparatus shown as a structural example of this invention. 1 is a schematic configuration diagram of a polishing apparatus to which the present invention is applied. It is a top view which shows the structural example of the leaf | plate spring which comprises a coupling part. (a) is an explanatory view showing an optical path change when the drive shaft and the polishing head are integrally moved up and down, and (b) is an explanation showing an optical path change when the drive shaft and the polishing head are relatively displaced in the vertical direction. FIG. (a) is a schematic diagram of a relative displacement detection unit viewed in the direction of arrows V-V in FIG. 1, and (b) is an arrow view in the same direction as (a) showing another configuration example of the relative displacement detection unit. It is. It is the block diagram seen from the front direction of the relative displacement detection part shown in FIG.5 (b).

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 2 shows a schematic configuration diagram of a polishing apparatus to which the present invention is applied. First, an overall configuration of the polishing apparatus 1 will be described.

  The polishing apparatus 1 includes a work holding unit 10 that holds a glass substrate or a quartz substrate (hereinafter referred to as a substrate) W that is an object to be polished, and an arm swing that horizontally swings a polishing arm 21 with respect to the work holding unit 10. Slurry is supplied to the polishing head 70 and the polishing processing section provided opposite to the substrate W held on the workpiece holding section 10 provided at the tip end of the mechanism 20 and the polishing arm 21 so as to be rotatable and vertically movable. A slurry supply mechanism (not shown), a control device 80 for controlling the operation of the polishing apparatus 1 such as rotation and vertical movement of the polishing head 70, rocking of the polishing arm, and supply of slurry to the polishing processing unit are configured. The

  The work holding unit 10 includes a substrate holder 11 that detachably sucks and holds the substrate W in a horizontal posture with the surface to be polished facing upward, a substrate driving shaft 14 that is connected to the substrate holder 11 and extends downward, and a substrate driving shaft 14. And a substrate rotating mechanism 15 for rotating the substrate holder 11 via the substrate holder 11.

  An arm swinging mechanism 20 is provided adjacent to the work holding unit 10, and a polishing head 70 is provided at the tip of the polishing arm 21 of the arm swinging mechanism 20. The arm swinging mechanism 20 includes a base 21a protruding upward from the table T of the polishing apparatus 1 and a polishing arm 21 having an arm portion 21b extending horizontally connected to the upper end of the base 21a, and the polishing arm 21 horizontally swinging. An arm swinging motor 22 is provided. The workpiece holder 10 and the arm swing mechanism 20 are positioned so that the substrate holder 11 is positioned on the swing locus of the polishing head 70 when the polishing arm 21 is horizontally swinged by the arm swing motor 22. It is prescribed. Therefore, the polishing arm 21 can be swung so that the polishing head 70 faces the substrate holder 11 and the polishing pad is pressed against the substrate W.

  A drive shaft 30 is disposed on the distal end side of the arm portion 21b so as to be rotatable around a rotation axis CL extending vertically and movable in the direction of the rotation axis (vertical direction). The drive shaft 30 is disposed above the drive shaft 30. A head rotating mechanism 40 for rotating and a head lifting / lowering mechanism 50 for moving the drive shaft 30 up and down are provided, and a polishing head 70 is connected to the lower portion of the drive shaft 30 via a coupling unit 60. The head rotation mechanism 40, the head lifting mechanism 50, the coupling unit 60, and the like will be described in detail later.

  The polishing head 70 has a pad holding portion 72 and a head shaft 74 extending upward from the center of the pad holding portion 72, and the head shaft 74 is connected to the drive shaft 30 via the coupling portion 60. A polishing pad 73 is affixed to the lower surface of the pad holding portion 72 and is disposed opposite to the substrate W held by the workpiece holding portion 10 in a horizontal posture with the polishing surface facing downward. The polishing pad 73 is appropriately selected and mounted according to the material of the object to be polished and the content of the polishing process. For example, a hard polyurethane pad having an independent foam structure is used.

  In the polishing apparatus 1 configured as described above, the arm swing mechanism 20 horizontally swings the polishing arm 21 to move the polishing head 70 above the workpiece holding unit 10, and the substrate rotation mechanism 15 of the workpiece holding unit 10. Then, the substrate holder 11 and the polishing head 70 are rotated by the head rotating mechanism 40, the polishing head 70 is lowered by the head lifting mechanism 50, and the polishing pad 73 is pressed against the substrate W. By polishing the polishing pad 73 horizontally while supplying the slurry, the polishing target surface of the substrate W can be subjected to CMP processing.

  In this polishing apparatus 1, a pressing force detection device 100 that detects the pressing force (polishing load) of the polishing pad against the substrate W is provided with the coupling unit 60 as the center. FIG. 1 includes a head rotation mechanism 40 that rotates the drive shaft 30, a head lifting mechanism 50 that moves the drive shaft 30 up and down, and a coupling unit 60 that connects the drive shaft 30 and the head shaft. A schematic configuration is shown, and the pressing force detection device 100 will be described in detail below with reference to FIG.

  The drive shaft 30 is roughly divided into a cylindrical rod-shaped shaft portion 31 that extends vertically along the rotation axis CL, and a bottomed cylindrical outer cylinder that is provided below the shaft portion 31 so as to open downward. For example, after turning a rod of a metal material such as a stainless alloy to form the shaft portion 31 and the outer cylinder portion 32, the shaft portion 31 and the outer cylinder portion 32 are connected together on the same axis with the axis line CL as a unit. Configured.

  Inside the polishing arm 21, support frame portions 23 and 24 serving as attachment bases of the respective mechanisms are formed. The drive shaft 30 is supported by the ball spline 25 at the shaft portion 31 and supported by the support frame portion 24 via a ball bearing 26 provided between the housing of the ball spline 25 and the support frame portion 24. Yes. For this reason, the drive shaft 30 is disposed so as to be movable up and down with respect to the support frame portions 23 and 24 by the action of the ball spline 25, and to the support frame portions 23 and 24 together with the ball spline 25 by the action of the ball bearing 26. It is rotatably arranged. The support frame portions 23 and 24 are integrally connected and fixed.

  The head rotation mechanism 40 includes a head drive motor 41 fixed to the support frame portion 23, a timing pulley 42 fixed to the spindle of the head drive motor, a timing pulley 43 fixed to the housing of the ball spline 25, and timings thereof. A timing belt 44 is wound around pulleys 42 and 43. In the head rotation mechanism 40 having such a configuration, when the head drive motor 41 is driven to rotate, the rotation of the spindle is transmitted to the housing of the ball spline 25 via the timing belt 44, and the drive shaft 30 is rotated together with the ball spline 25. The

  The head lifting mechanism 50 is mainly composed of a lifting cylinder 51 having a cylinder body fixed to the support frame portion 23 and a piston rod connected to the shaft portion 31 of the drive shaft. The piston rod of the elevating cylinder 51 and the shaft portion 31 of the drive shaft are connected via a thrust bearing (not shown) capable of transmitting a force in the direction of the rotation axis. While the thrust of the cylinder 51 is transmitted to the drive shaft 30, the force in the angular direction accompanying the rotation of the drive shaft 30 is not transmitted to the elevating cylinder 51. Therefore, air is supplied to the tube side cylinder chamber of the elevating cylinder 51 and the piston rod is extended, or air is supplied to the rod side cylinder chamber and the piston rod is contracted to rotate the head rotating mechanism 40. The drive shaft 30 in the state can be moved up and down.

  The polishing head 70 is connected to the drive shaft 30 disposed so as to be movable up and down through the coupling portion. The coupling unit integrally rotates the drive shaft 30 and the polishing head 70 around the rotation axis CL, while the drive shaft 30 and the polishing head 70 can be elastically relatively displaced in the extending direction of the rotation shaft CL, that is, in the vertical direction. Configured to connect to.

  FIG. 1 shows a configuration using a parallel leaf spring as a configuration example of a coupling portion having such a function. The coupling portion 60 is provided on the drive shaft 30 and has a bottomed bottom. A cylindrical outer cylinder part 32, a head shaft 74 provided on the polishing head 70 and extending upward, and extending in the direction perpendicular to the rotation axis CL in the outer cylinder part 32, connect the outer cylinder part 32 and the head axis 74. And a plurality of (two in FIG. 1) leaf springs 61.

  For example, as shown in FIGS. 3A, 3B, and 3C, the leaf springs 61 provided in parallel in the vertical direction are formed by forming a plurality of arc-shaped slits 62 in a disk of a thin metal material, or fan-shaped punching openings. A plurality of 63 or a plurality of strip-shaped plate springs 64 are combined to appropriately adjust the material, plate thickness, and shape in accordance with a required elastic coefficient (spring constant). The outer cylinder portion 32 and the head shaft 74 are divided into a plurality of upper and lower outer cylinder members, with an interval holding member having a size matching the arrangement interval of the upper and lower leaf springs 61 interposed therebetween. These are integrally connected and fixed by sandwiching the leaf spring 61 between the (shaft member) and the spacing member, so that the head shaft 74 is positioned at the axis of the drive shaft 30 and inside the outer cylinder portion 32. An integral coupling portion 60 is formed in which the upper and lower leaf springs 61 and 61 are disposed in parallel.

  When the coupling portion 60 is formed, the polishing head 70 is connected to the drive shaft 30 so as to be relatively displaceable with a predetermined elastic coefficient in the rotation axis direction by the action of a parallel leaf spring, and in the rotation angle direction, the plate is disposed in the rotation angle direction. Due to the rigidity of the spring 61, the drive shaft 30 and the polishing head 70 are integrally rotated without relative displacement (the displacement amount is extremely small). At this time, the head shaft 74 moves vertically up and down along the rotation axis CL by the action of the parallel leaf spring. When the substrate W is not a parallel flat plate, for example, when the substrate W is a curved surface having a large curvature, the head shaft 74 is connected to the head shaft 74 through a spherical bearing. Moves vertically along the rotation axis CL without tilting.

  The pressing force detection device 100 is detected by a relative displacement detection unit 110 that detects the relative displacement amount of the drive shaft 30 and the polishing head 70 in the rotation axis direction of the coupling unit 60 in a non-contact manner, and the relative displacement detection unit 110. And an arithmetic processing unit 120 that calculates the pressing force of the polishing pad 73 based on the relative displacement amount and the elastic coefficient of the coupling unit 60 set in advance. The arithmetic processing unit 120 is provided in a control device 80 configured using a microcomputer, and an elastic coefficient (upper and lower leaf springs 61, 61) in the rotational axis direction of the coupling unit 60 is stored in a memory in the control device 80. The spring constant (k) of the parallel leaf spring constituted by the above is preset and stored.

  The relative displacement detector 110 is provided in the opposing part of the driving shaft 30 and the polishing head 70 facing each other in the coupling part, and the reflecting surface is arranged in parallel at the same inclination angle on the plane (axial plane) including the rotation axis CL. The first reflecting member 111 and the second reflecting member 112, and the probe light in the horizontal direction perpendicular to the rotation axis in the axial plane is provided on the support frame portion 24 located on the outer peripheral side of the opposing portion of these reflecting members. A light source 115 that emits PB and illuminates the first reflecting member, and a probe light provided on the opposite side of the light source 115 across the rotation axis CL is reflected by the first reflecting member 111 and the second reflecting member 112 and emitted. The position detector 116 is configured to receive the reflected light RB and detect the position of the reflected light.

  In the configuration shown in FIG. 1, reflecting mirrors are used as the first reflecting member 111 and the second reflecting member 112, and the first reflecting member 111 is fixed to the upper end of the head shaft 74 at an inclination angle of 45 degrees with respect to the rotation axis CL. Then, the case where the second reflecting member 112 is fixed to the center of the bottom portion of the outer cylinder portion 32 located immediately above the same so that the anti-inclined surfaces face each other at the same inclination angle is illustrated. The reflecting members 111 and 112 may use prisms or the like, and the inclination angles of the first reflecting member 111 and the second reflecting member 112 may be other angles (for example, 60) as long as the anti-inclined surfaces are arranged in parallel. Degree).

  The light source 115 is provided at the lower end of a stay 117 that is fixed to the support frame portion 24 and extends downward. For example, an LED or a laser diode is used, and the probe light PB emitted toward the rotation axis CL is parallel light. Alternatively, an optical system that adjusts the beam divergence angle is attached as necessary so that the light is slightly convergent.

  The position detector 116 is located on the opposite side of the light source 115 across the rotation axis CL, that is, on the extension line of the optical axis of the probe light PB emitted from the light source 115 and passing through the rotation axis CL in plan view. 24 is provided at the lower end of a stay 118 that extends downward from 24. The position detector 116 is a sensor that receives the reflected light RB that is reflected horizontally by the first and second reflecting members 111 and 112 and detects the position of the reflected light RB in the rotation axis direction. A PSD (Position Sensor Diode) is used.

  The outer cylindrical portion 32 has an axial plane in which the anti-inclined surfaces of the first reflecting member 111 and the second reflecting member 112 are opposed at an inclination angle of 45 degrees (the driving shaft 30 is in an angular position state shown in FIG. The probe light PB emitted horizontally from the light source 115 on the circumferential surface (the right circumferential surface in FIG. 1) on which the reflective surface of the first reflective member 111 is oriented. A light introducing portion 33 to be introduced into the first reflecting member 111 in the portion 32 is formed in an opening, and the first reflecting member is formed on the peripheral surface (the left peripheral surface in FIG. 1) on which the reflecting surface of the second reflecting member 112 is oriented. A light deriving portion 34 for deriving the reflected light RB reflected by the 111 and the second reflecting member 112 and propagating horizontally from the outer tube portion 32 is formed as an opening. Note that a window member (for example, a glass window) that transmits light emitted from the light source 115 may be provided in the light introducing unit 33 and the light deriving unit 34.

  For this reason, the probe light PB emitted horizontally from the light source 115 toward the rotation axis enters the outer cylindrical portion 32 from the light introducing portion 33 when the drive shaft 30 is at the angular position of the measurement angle plane. Reflected by the first reflecting member 111 and the second reflecting member 112 constituting a pair of parallel mirrors whose opposite slopes are arranged opposite to each other in parallel, the reflected light RB enters the position detector 116 from the light deriving unit 34. The position detector 116 outputs a detection signal corresponding to the position of the detected reflected light in the rotation axis direction to the arithmetic processing unit 120.

  Here, in a state where the polishing pad 73 and the substrate W are not in contact with each other, or in a state where the load between the polishing pad 73 and the substrate W is not changed and the surface of the substrate W having a curvature is swung, the drive shaft is driven. Even if 30 is moved up and down, the load acting on the leaf spring 61 does not change. For this reason, the drive shaft 30 and the polishing head 70 connected via the coupling unit 60 move up and down integrally, and the first reflecting member 111 and the second reflecting member 112 move up and down while maintaining the relative positional relationship. To do. FIG. 4A shows the change in the optical path at this time. Even if the first reflecting member 111 and the second reflecting member 112 move up and down, the reflected light is incident on the position detector 116 due to the action of the parallel mirror. The RB axial position does not change.

  On the other hand, when the polishing pad 73 is in contact with the substrate W and the drive shaft 30 is moved downward to press the polishing pad 73 against the substrate W, an upward load acts on the central portion of the leaf spring 61 and elastically deforms. The head shaft 74 is displaced relative to the outer cylinder portion 32 in the rotation axis direction. At the contact portion between the polishing pad 73 and the substrate W, a load F (F = kx) corresponding to the product of the relative displacement amount x between the outer cylinder portion 32 and the head shaft 74 and the spring constant k of the parallel leaf spring. Works.

  FIG. 4B shows the state of the optical path change when the drive shaft 30 and the polishing head 70 are relatively displaced in the direction of the rotation axis as described above, and the second is provided in the outer cylinder portion 32. A change when the first reflection member 111 provided on the head shaft 74 moves upward relative to the reflection member 112 is indicated by a one-dot chain line, and a change when the first reflection member 111 moves downward is indicated by a two-dot chain line. Is shown. As is apparent from this figure, when the first reflecting member 111 is relatively displaced up and down by x, the reflected light incident on the position detector 116 is displaced by the same displacement amount x in the up and down direction. Therefore, the relative displacement amount x between the drive shaft 30 and the polishing head 70 can be obtained by detecting the position of the reflected light RB detected by the position detector 116 and calculating the amount of change. As understood from this, the arrangement of the light source 115 and the position detector 116 may be reversed.

  The detection signal of the position of the reflected light RB detected by the position detector 116 is input to the arithmetic processing unit 120, and the arithmetic processing unit 120 receives the detection signal input intermittently as the drive shaft 30 rotates. The relative displacement amount x in the rotation axis direction between the drive shaft 30 and the polishing head 70 is sequentially obtained, and based on the obtained relative displacement amount x and the elastic coefficient k of the coupling unit 60 that is preset and stored in the memory. Thus, the pressing force of the polishing pad 73 against the substrate W, that is, the polishing load F is calculated.

  The control device 80 compares the polishing load F thus calculated with the polishing load (load command) set in the processing program for the substrate W, and supplies air to the lift cylinder 51 based on the comparison result. Feedback control of the pressure. Thereby, the substrate W is polished with high accuracy by the polishing load set in the processing program.

  In FIG. 4, the inclination angle θ of the anti-inclined surfaces of the first reflecting member 111 and the second reflecting member 112 is added. However, when the inclination angle θ is 45 degrees as in this configuration, the drive shaft 30 and The relative displacement amount x of the polishing head 70 and the amount of change in the position of the reflected light RB incident on the position detector 116 are the same, and the configuration of the pressing force detection device can be made small and simple. On the other hand, when the inclination angle θ is set to be larger than 45 degrees (for example, when θ = 60 degrees), the relative displacement amount x between the drive shaft 30 and the polishing head 70 is incident on the position detector 116. The amount of change in position of the reflected light RB in the rotation axis direction is enlarged. Therefore, according to such a configuration, it is possible to detect the polishing load with higher accuracy and perform feedback control.

  In the above, an example in which the first reflecting member 111 and the second reflecting member 112 are arranged to face each other on the rotation axis CL to configure a pair of parallel mirrors has been described. It is also possible to provide a pair or a plurality of pairs at a position away from the rotation axis. FIG. 5A shows a schematic diagram viewed in the direction of arrows V-V in FIG. 1 as a comparison target, and the relative displacement detector 110 ′ of another configuration form is shown in the same direction of arrow as in FIG. FIG. 5 (b) shows an arrow view seen in FIG. 5, and FIG. 6 shows a configuration diagram seen from the front direction.

  In the relative displacement detection unit 110 ′, a disk-like reflection member support portion 75 is fixed to the upper portion of the head shaft 74 so as to face the bottom surface of the outer cylinder portion 32, and the reflection member support portion 75 and the outer cylinder portion 32 are fixed. The first reflecting member 111 and the second reflecting member 112 are arranged to be opposed to each other at an odd angle pair (three pairs in FIG. 5) at an equal angular pitch at a predetermined radial position on the bottom surface. The circumferential surface of the outer cylindrical portion 32 where the anti-inclined surface of each first reflecting member 111 is oriented and the circumferential surface of the outer cylindrical portion 32 where the anti-inclining surface of each second reflecting member 112 is oriented are on a straight line passing through the rotation axis CL. The light introduction part 33 and the light lead-out part 34 are formed in an opening.

  Therefore, the probe light PB emitted horizontally from the light source 115 toward the rotation axis CL and introduced from the light introduction part 33 into the outer cylinder part is reflected by the first and second reflection members 111 and 112 and seen in a plan view. The light passes through the rotation axis CL, is emitted horizontally from the light derivation unit 34, and enters the position detector 116. The relative displacement between the drive shaft 30 and the polishing head 70 is detected in the same manner as the pressing force detection device 100 described above. According to such a configuration, a plurality of detection signals can be acquired according to the number of arranged pairs of the first and second reflecting members 111 and 112 while the drive shaft 30 makes one rotation. Therefore, according to such a configuration, the relative displacement between the drive shaft 30 and the polishing head 70, that is, the polishing load calculated based on the displacement and the time change thereof can be detected in a shorter time interval, and higher-speed feedback control can be performed. Is possible.

  As described above, in the pressing force detection device 100 of the present invention, the drive shaft 30 is driven with respect to the drive shaft 30 that is supported and driven by the support frame portions 23 and 24 so as to be rotatable and movable in the rotation axis direction. And a polishing head 70 are connected to be elastically displaceable only in the direction of the rotation axis, and the relative displacement between the drive shaft 30 and the polishing head 70 is detected by the relative displacement detector 110. Thus, the polishing load is calculated based on the detected relative displacement amount and the elastic coefficient of the coupling portion. For this reason, the calculated polishing load does not include loss components such as the sliding resistance of the elevating cylinder 51 and the rolling resistance of the ball bearing 26 and the ball spline 25, and errors due to these resistances are eliminated. Thus, the polishing load can be accurately detected. As a result, the pressure term of the Preston equation for polishing can be controlled to be constant or dynamic, and the polishing performance and polishing accuracy can be improved.

  In addition, by connecting the drive shaft 30 and the polishing head 70 with the leaf spring 61 in the coupling portion 60, it is possible to improve the detection accuracy of the polishing load without including a resistance component in the connection portion. . Further, since the first and second reflecting members 111 and 112 are provided in the upper part of the outer cylindrical portion 32, the detection accuracy does not decrease due to the slurry or the like adhering to the anti-slope, and high detection accuracy. Can be stably maintained for a long time.

  In the above-described embodiment, the configuration in which the light emitted from the light source 115 passes through the axis of the rotation axis CL in the coupling unit 60 is illustrated as the relative displacement detection unit, but passes through a position away from the axis. A pair of parallel mirrors 111 and 112 may be arranged to face each other at a radial position according to the configuration. Moreover, although the case where it comprised with a pair of parallel mirror 111,112, the light source 115, and the position detector 116 was illustrated, the relative displacement detection part can detect the relative displacement amount of the drive shaft 30 and the grinding | polishing head 70 by non-contact. For example, the relative movement amount of the head shaft 74 with respect to the outer cylindrical portion 32 may be detected by a capacitance sensor, a magnetic sensor, or the like.

CL rotation axis W substrate (object to be polished)
PB Probe light RB Reflected light 1 Polishing apparatus 10 Work holding part 23, 24 Support frame part (base)
30 drive shaft (31: shaft portion, 32: outer cylinder portion)
40 Head rotation mechanism 50 Head lifting mechanism 60 Coupling part (61: leaf spring)
70 Polishing head (73: Polishing pad, 74: Head shaft)
100 Pressing force detection device 110, 110 'Relative displacement detector (relative displacement detector)
111 First reflective member 112 Second reflective member 115 Light source 116 Position detector 120 Arithmetic processing unit

Claims (4)

A drive shaft disposed on the base so as to be rotatable and movable in the direction of the rotation axis, a polishing head connected to the drive shaft via a coupling portion, and a polishing object provided facing the polishing head A workpiece holding unit that holds the workpiece, and rotates the drive shaft and moves in the direction of the rotation axis so that the polishing pad mounted on the polishing head is pressed against the object to be polished held by the workpiece holding unit for polishing. In a polishing apparatus configured to perform processing,
The coupling unit integrally rotates the drive shaft and the polishing head in the rotation direction of the drive shaft, and connects the drive shaft and the polishing head in the rotation axis direction so that they can be elastically displaced relative to each other. Configured to
A relative displacement detection means for detecting a relative displacement amount in the rotation axis direction between the drive shaft and the polishing head in the coupling portion in a non-contact manner;
The polishing pad with respect to the object to be polished based on a preset elastic coefficient of the coupling portion and a relative displacement amount of the driving shaft and the polishing head detected by the relative displacement detecting unit in the rotation axis direction. An apparatus for calculating a pressing force of a polishing apparatus, comprising: an arithmetic processing unit that calculates a pressing force of the polishing apparatus.   2. The polishing apparatus according to claim 1, wherein in the coupling portion, the drive shaft and the polishing head are connected by a plurality of plate springs extending in a direction orthogonal to the rotation shaft and provided in parallel. Pressure detection device. The relative displacement detection means is
A first reflecting member and a second reflecting member, which are provided at opposing portions of the driving shaft and the polishing head facing each other in the coupling portion, and whose reflecting surfaces are arranged in parallel at the same inclination angle on an axial plane including the rotating shaft. A reflective member;
A light source that is located on the outer peripheral side of the facing portion and is provided on the base, emits probe light orthogonal to the rotation axis in the axial plane to illuminate the first reflecting member, and sandwiches the rotation axis A position detector that is provided on the opposite side of the light source and receives reflected light that is reflected and emitted by the first reflecting member and the second reflecting member and detects the position of the reflected light;
The arithmetic processing unit calculates a relative displacement amount in the rotation axis direction of the drive shaft and the polishing head from a change in the position of the reflected light input from the position detector, and calculates the calculated relative displacement amount. The pressing force detection device for a polishing apparatus according to claim 1, wherein the pressing force of the polishing pad against the object to be polished is calculated based on a preset elastic coefficient of the coupling portion. The coupling portion includes a bottomed cylindrical outer cylinder portion provided on the drive shaft so as to extend in the rotation axis direction, and is provided on the polishing head so as to extend in the rotation axis direction. A head shaft disposed; and the plurality of leaf springs extending in a direction orthogonal to the rotation axis in the outer cylinder portion and connecting the outer cylinder portion and the head shaft.
One of the first reflecting member and the second reflecting member is provided at the bottom portion of the outer cylinder portion, and the other is provided at the shaft end portion of the head shaft facing the bottom portion,
A light introduction part for introducing the probe light emitted from the light source into the first reflection member in the outer cylinder part is formed on the peripheral surface of the outer cylinder part where the reflection surface of the first reflection member is oriented. A light derivation for deriving the reflected light reflected by the first reflecting member and the second reflecting member from the outer tube portion on the peripheral surface of the outer tube portion where the reflecting surface of the second reflecting member is oriented. The pressing force detection device for a polishing apparatus according to claim 3, wherein a portion is formed.

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