Machining apparatus

Abstract

To provide a processing device capable of suitably measuring a surface shape of a measuring object by suppressing an error caused by vibration.SOLUTION: A holding unit including a holding surface that holds a workpiece, a processing unit that processes the workpiece held by the holding unit, and a shape measuring unit that measures a surface shape of a measurement target, the shape measuring unit emitting measurement light, and an optical path relay that receives the measurement light emitted from the autocollimator, changes a direction of the measurement light by a predetermined angle, irradiates the surface of the measurement target with the measurement light, receives the measurement light reflected by the surface of the measurement target, changes the direction of the measurement light by the predetermined angle, and guides the measurement light to the autocollimator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a processing apparatus for performing processing such as polishing on semiconductor wafers and the like. [Background technology]

[0002] Device chips incorporated into various electronic devices such as mobile phones and personal computers are manufactured, for example, by the following procedure: A plurality of streets (planned dividing lines) arranged in a grid pattern are defined on the surface of a semiconductor wafer substrate made of silicon or other material, and devices are formed in each of the plurality of areas defined by these streets. The substrate is then divided along the streets to obtain chips equipped with devices (device chips).

[0003] In recent years, with the miniaturization of electronic devices, there has been a demand for thinner chips, and to achieve this, the substrate may be ground before being separated.

[0004] A grinding device used for grinding substrates includes a holding table for holding the workpiece and a grinding unit for grinding the workpiece. The grinding unit includes a spindle with a grinding wheel attached to the tip. The workpiece is held by the holding table, and the grinding stone is brought into contact with the workpiece while rotating the holding table and the grinding wheel, thereby grinding the workpiece.

[0005] After grinding the workpiece, the surface to be ground is polished. The polishing device used for polishing includes a holding table that holds the workpiece and a polishing unit that polishes the workpiece. The polishing unit includes a spindle at the tip of which a disc-shaped polishing pad is attached. The workpiece is held by the holding table, and the polishing pad is brought into contact with the workpiece while rotating the holding table and the polishing pad, thereby polishing the workpiece.

[0006] In various processing devices such as the grinding device and polishing device described above, the surface shapes of various objects may be measured for the purpose of maintaining processing quality, etc. For example, in a grinding device, if the surface shape of the holding surface of the holding table is rough, it may lead to defects such as cracking or chipping of the wafer, which is the workpiece. Therefore, the surface shape of the holding surface is measured as necessary, and if it is determined to be rough, self-grinding (a process of grinding the holding surface of the holding table with a grinding wheel) is performed (see, for example, Patent Document 1).

[0007] In addition, for example, the surface shape of a wafer, which is the workpiece, may be measured, or the surface shape of a polishing pad in a polishing device may be measured. If deformation or clogging due to wear is found, the polishing pad may be dressed, or, depending on its condition, the polishing pad may be removed and replaced with a new one.

[0008] Conventionally, such measurements have often been performed using a laser displacement meter, which measures the distance to the object by irradiating the object with a measurement light. The laser displacement meter is moved relative to the object, measuring the distance between the laser displacement meter and the object, and the surface shape of the object is measured as a distribution of distances according to location on the surface of the object.

[0009] However, when measuring an object by moving the laser displacement meter relative to it, the movement can cause vibrations in the laser displacement meter, which can affect the measurement values ​​obtained by the laser displacement meter and potentially result in errors.

[0010] On the other hand, especially in recent years, as device chips have become smaller and more complex, higher processing quality is required, which in turn requires higher accuracy in measuring the surface shape described above. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Publication No. 2018-94671 Summary of the Invention [Problem to be solved by the invention]

[0012] An object of the present invention is to provide a processing apparatus that can suitably measure the surface shape of a measurement object while suppressing errors due to vibration. [Means for solving the problem]

[0013] According to one aspect of the present invention, there is provided a processing apparatus comprising: a holding unit having a holding surface for holding a workpiece; a processing unit for processing the workpiece held by the holding unit; and a shape measurement unit for measuring the surface shape of a measurement object, wherein the shape measurement unit emits fixed light and receives the measurement light reflected from the surface of the measurement object to measure the angle of the surface of the measurement object at the position where the measurement light is irradiated; and an optical path repeater that receives the measurement light emitted from the autocollimator, changes the direction of the measurement light by a predetermined angle to irradiate the surface of the measurement object, receives the measurement light reflected from the surface of the measurement object, changes the direction of the measurement light by the predetermined angle, and guides it to the autocollimator.

[0014] Preferably, the optical path repeater is configured to be movable, and a controller is provided that controls the irradiation of measurement light from the autocollimator through the optical path repeater onto the surface of the object to be measured while moving the optical path repeater.

[0015] Preferably, the optical path repeater is configured to be movable along a direction parallel to the holding surface of the holding unit, and the holding unit is configured to be rotatable around an axis intersecting the holding surface, and a controller is provided that moves the optical path repeater while rotating the holding unit and controls the irradiation of measurement light from the autocollimator through the optical path repeater toward the holding surface.

[0016] Preferably, the processing unit includes a polishing pad for polishing the holding surface of the holding unit or the workpiece held on the holding surface, and the shape measurement unit is configured to measure the surface shape of the polishing pad as the measurement object.

[0017] Preferably, the processing unit includes a spindle to which the polishing pad is attached and which rotates together with the polishing pad, and the optical path repeater is configured to be movable along a direction parallel to the polishing surface of the polishing pad, and includes a controller that moves the optical path repeater while rotating the spindle and controls the irradiation of measurement light from the autocollimator through the optical path repeater toward the polishing surface of the polishing pad.

[0018] Preferably, the measuring device further comprises a determination section that makes a determination regarding the surface shape of the measurement object measured by the shape measuring unit, and a notification section that issues an alarm in accordance with the result of the determination by the determination section. [Effects of the Invention]

[0019] According to one aspect of the present invention, the processing apparatus measures the surface shape of the object by irradiating the measurement light emitted from the autocollimator onto the surface of the object through a light path relay and measuring the angle of the surface of the object. In this way, it is possible to measure the surface shape of the object based on a different principle from conventional methods. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a front view schematically showing an example of the configuration of a processing device. [Figure 2] FIG. 2 is a conceptual diagram that schematically shows how the processing apparatus of FIG. 1 measures the surface shape of a measurement object. [Figure 3] FIG. 3 is a front view showing how the surface shape of the polishing pad is measured in the processing apparatus of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings, in which: Fig. 1 is a front view showing a schematic configuration example of a processing device;

[0022] The processing device 2 in this embodiment is a polishing device that polishes workpieces such as semiconductor wafers. However, the processing device is not limited to a polishing device, and may be, for example, a grinding device or a processing device that has both grinding and polishing functions. In addition, various other devices may be considered as processing devices.

[0023] In Figure 1, the X-axis, Y-axis, and Z-axis represent three mutually orthogonal directions in three-dimensional space. The XY plane defined by the X-axis and Y-axis is parallel to the horizontal plane, and the Z-axis is parallel to the vertical direction.

[0024] In this specification, expressions such as "along the X direction" and "along a direction parallel to the holding surface" are used, but these do not necessarily mean that the direction of an object or its movement, the angle of a light ray, etc., strictly coincide with or are parallel to these axes or planes. For example, they may be at a slight angle to each other but generally face the same direction, or the direction of an object or its movement, the angle of a light ray, etc., may include a directional component.

[0025] The polishing apparatus 2 includes a holding unit 6 for holding the workpiece 4, a processing unit (polishing unit) 8 for polishing the workpiece 4 held by the holding unit 6, and a shape measuring unit 10 for measuring the surface shape of a measurement object such as the workpiece 4.

[0026] The holding unit 6 is a chuck table that holds the workpiece 4, such as a plate-shaped semiconductor wafer, and holds the workpiece 4 by suction.

[0027] The holding unit 6, which is a chuck table, has a disk-shaped table base 12 made of metal or the like, and an adsorption plate 14 attached to the table base 12.

[0028] The suction plate 14 is a disk-shaped member made of, for example, porous ceramics. A disk-shaped recess corresponding to the dimensions of the suction plate 14 is formed in the upper part of the table base 12, and the suction plate 14 is fixed so as to fit into this recess. A flow path (not shown) is formed inside the table base 12, and one end of the flow path is connected to the underside of the suction plate 14.

[0029] The other end of the flow path provided in the table base 12 is connected to a suction source (not shown) such as an ejector, and when the suction source is operated, negative pressure supplied into the flow path acts on an object such as the workpiece 4 placed on the upper surface 14a of the suction plate 14. In this way, the upper surface 14a of the suction plate 14 functions as a holding surface that holds the workpiece 4.

[0030] A rotation mechanism (not shown) that rotates the holding unit 6 around a rotation axis along the Z direction (a rotation axis extending in a direction intersecting the holding surface 14a) is connected to the lower part of the holding unit 6.

[0031] The holding unit 6 may be configured to be movable along the X direction, Y direction, or Z direction, or along a plurality of these directions, by a movement mechanism (not shown).

[0032] A processing unit 8 is provided above the holding unit 6. The processing unit 8 in this embodiment is a polishing unit that polishes the workpiece 4 held by the holding unit 6.

[0033] The polishing unit 8 includes a spindle housing 16 and a spindle 18 housed in the spindle housing 16 .

[0034] The spindle housing 16 is a hollow housing having a cylindrical shape as a whole, and is disposed so that the axial direction of the cylinder is along the Z direction. A part of the cylindrical spindle 18 is accommodated inside the spindle housing 16.

[0035] The spindle 18 is a cylindrical article made of, for example, metal, and is housed in the spindle housing 16 with the axis of the cylinder aligned along the Z direction. A rotation drive source such as a servo motor is connected to the base end (upper end) of the spindle 18, and operation of the rotation drive source causes the spindle 18 to rotate relative to the spindle housing 16 around the axis of the cylinder.

[0036] A disk-shaped mount 22 for mounting a polishing pad 20 for polishing is provided at the tip (lower end) of the spindle 18. The polishing pad 20 mounted below the mount 22 has a disk-shaped pad base 20a having approximately the same diameter as the mount 22, and a disk-shaped polishing layer 20b fixed to the underside of the pad base 20a.

[0037] Pad base 20a is formed, for example, from a material such as metal. Polishing layer 20b is a fixed abrasive layer with abrasive grains dispersed therein, and its lower surface functions as the polishing surface of polishing pad 20 for polishing a workpiece. For example, polishing layer 20b is produced by impregnating a polyester nonwoven fabric with a urethane solution in which abrasive grains are dispersed, followed by drying.

[0038] The abrasive grains contained in the polishing layer 20b are made of materials such as SiC (silicon carbide), cBN (cubic boron nitride), diamond, or metal oxide particles. i Examples of the polishing layer include O2 (silica), CeO2 (ceria), ZrO2 (zirconia), and Al2O3 (alumina). Note that polishing pad 20 may also be a polishing pad having a polishing layer with a different configuration (for example, a polishing layer that does not contain abrasive grains).

[0039] The spindle housing 16 is supported so as to be movable in the Z direction by a Z-axis movement mechanism 24. The Z-axis movement mechanism 24 is a mechanism that moves the spindle 18 and the holding unit 6 relatively in the Z direction.

[0040] In this embodiment, the Z-axis moving mechanism 24 is configured as a mechanism for moving the spindle 18 side, but the Z-axis moving mechanism may also be a mechanism for moving the holding unit 6 side, or both the spindle 18 and the holding unit 6.

[0041] The Z-axis movement mechanism 24 includes a pair of guide rails 26 arranged along the Z direction relative to a frame constituting the polishing apparatus 2, and a movement table 28 slidably attached to the guide rails 26. A ball screw 30 is arranged along the Z direction between the pair of guide rails 26. Note that only one of the pair of guide rails 26 is shown in FIG. 1.

[0042] The spindle housing 16 is fixed to the front surface of the moving table 28. A nut portion (not shown) is provided on the back surface of the moving table 28. A ball screw 30 is rotatably connected to the nut portion. A rotational drive source 32 such as a pulse motor is connected to the upper end of the ball screw 30. When the rotational drive source 32 operates to rotate the ball screw 30 about its own axis, the moving table 28 moves up and down in the Z direction together with the spindle housing 16.

[0043] The shape measurement unit 10 includes an autocollimator 34 and an optical path repeater 36 .

[0044] The autocollimator 34 is a device that emits a laser beam as measurement light, receives the measurement light reflected from the surface of the object with an image sensor, and measures the angle of the surface of the object at the position where the measurement light is irradiated based on the position where the measurement light is received on the image sensor. In this way, the autocollimator 34 can detect minute angles on the surface of the object.

[0045] In the polishing apparatus 2 of this embodiment, the measurement objects of the shape measuring unit 10 are assumed to be the suction plate 14 of the holding unit 6, the workpiece 4 held by the holding unit 6, the polishing pad 20 attached to the polishing unit 8, etc. Accordingly, the optical path repeater 36 is configured to be movable in a direction parallel to the holding surface 14a of the holding unit 6 and the polishing surface of the polishing pad 20 (along the X direction).

[0046] As the autocollimator 34, for example, a device having appropriate functions (accuracy, measurement distance, measurement range, etc.) depending on the application can be selected from among general autocollimators available on the market.

[0047] The optical path repeater 36 is an optical element that includes a first reflecting surface 36a and a second reflecting surface 36b configured as surfaces that reflect light, and that reflects light incident on the first reflecting surface 36a at the first reflecting surface 36a and the second reflecting surface 36b and then emits the light. The angle between the light that enters the optical path repeater 36 and the light that exits from the optical path repeater 36 is constant depending on the angle between the first reflecting surface 36a and the second reflecting surface 36b.

[0048] If the angle between the first reflecting surface 36a and the second reflecting surface 36b is θ and the angle between the light incident on the first reflecting surface 36a and the light reflected by the second reflecting surface 36b is φ, the following relationship holds between the two: φ=2θ (0<θ≦90°) φ=360°-2θ (90°<θ<180°)

[0049] For example, when θ=45°, the angle between the light incident on the optical path repeater and the light emitted from the optical path repeater is always 90°, regardless of the angle of incidence to the optical path repeater .

[0050] The pentaprism or pentamirror is a device equivalent to the optical path repeater 36 when θ=45°, and a commercially available pentaprism or pentamirror can be used as the optical path repeater 36.

[0051] 1, the optical path repeater 36 is disposed above the holding unit 6 and below the polishing unit 8. In the optical path repeater 36, the first reflecting surface 36a and the second reflecting surface 36b are disposed at an angle of 45° to each other.

[0052] The autocollimator 34 is provided at the same height as the optical path repeater 36, and emits measurement light L from there to the optical path repeater 36 in a direction along the XY plane. The optical path repeater 36 receives the measurement light L, changes the direction of the measurement light L by a predetermined angle (e.g., 90°), and irradiates the measurement light L onto the measurement object (e.g., the suction plate 14 of the holding unit 6 located below). The optical path repeater 36 also receives the measurement light L reflected by the measurement object, changes the direction of the measurement light L by the same predetermined angle, and guides it back to the autocollimator 34.

[0053] The autocollimator 34 receives the light that is reflected by the object to be measured and returns via the optical path repeater 36, and measures the angle of the object to be measured according to the reception position of the measurement light L on the built-in image sensor.

[0054] It should be noted that other optical elements such as a mirror or a beam splitter may be provided as appropriate in the optical path from the autocollimator 34 to the object to be measured.

[0055] The optical path repeater is configured to move relative to the autocollimator 34. In the present embodiment, the optical path repeater is provided so as to be movable in the X direction by an X-axis movement mechanism .

[0056] The X-axis movement mechanism 38 includes a pair of guide rails 40 arranged along the X direction with respect to a frame constituting the polishing apparatus 2, and a movement table 42 slidably attached to the guide rails 40. A ball screw 44 is arranged between the pair of guide rails 40 along the X direction.

[0057] The optical path repeater 36 is attached to the front surface of the moving table 42 via a support member 48. A nut portion (not shown) is provided on the back surface of the moving table 42. A ball screw 44 is rotatably connected to the nut portion. A rotation drive source 46 such as a pulse motor is connected to the upper end of the ball screw 44. When the rotation drive source 46 operates to rotate the ball screw 44 about its own axis, the moving table 42 moves in the X direction together with the support member 48 and the optical path repeater 36.

[0058] 1, extends from the moving table 42 located at the rear side of the paper surface to the front side in the Y direction, and supports the optical path repeater 36 at its tip. The support member 48 expands and contracts in the Y direction by a mechanism (not shown), thereby enabling the position of the optical path repeater 36 in the Y direction to be adjusted.

[0059] The optical path repeater 36 is also configured to rotate about an axis along the X direction by a mechanism (not shown) provided on the support member 48, for example.

[0060] The autocollimator 34 is supported by a member (not shown) or the like relative to a frame constituting the polishing apparatus 2, and is configured to move along the Y direction by a mechanism (not shown). The autocollimator 34 may also be configured to move in the X and Z directions.

[0061] The operation of each component of the polishing apparatus 2, such as the holding unit 6, the polishing unit 8, and the shape measuring unit 10, is controlled by a controller 50. In particular, in the case of the polishing apparatus 2 of this embodiment, the controller 50 is equipped with a measurement unit 50a that measures the angle of the surface of the measurement object using the autocollimator 34 of the shape measuring unit 10 and acquires the surface shape, and a determination unit 50b that makes a determination regarding the surface shape based on the measurement result by the measurement unit 50a.

[0062] The controller 50 is configured by a computer having a processor such as a CPU (Central Processing Unit) and a memory. The memory includes a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a flash memory.

[0063] The auxiliary storage device stores software, and the functions of the controller 50 are realized by operating the processor and other components in accordance with this software.

[0064] The controller 50 is connected to an alarm unit 52. The alarm unit 52 is a mechanism for issuing some kind of alarm to the outside, such as a warning light or buzzer, and issues the alarm in response to the result of the determination by the determination unit 50b. For example, the alarm unit 52 may be configured as a monitor display or the like for operating and monitoring the operation of the polishing apparatus 2.

[0065] Measurement of the surface shape of a measurement object in the polishing apparatus 2 of this embodiment will be described.

[0066] When the object to be measured is, for example, the suction plate 14 of the holding unit 6 or the workpiece 4 held by the holding unit 6, an optical path repeater 36 is disposed above the holding unit 6, as shown in Fig. 1. The measurement light L emitted from the autocollimator 34 is incident on this optical path repeater 36 along the X direction.

[0067] When the optical path repeater 36 is a pentaprism or a pentamirror, the angle formed by the first reflecting surface 36a and the second reflecting surface 36b is 45°, and the measurement light L incident on the first reflecting surface 36a is reflected by the first reflecting surface 36a and the second reflecting surface 36b, and is emitted from the optical path repeater 36 at an angle changed by 90°.

[0068] If the orientation of the optical path repeater 36 is set so that the measurement light L is reflected directly downward by the second reflecting surface 36b, the measurement light L emitted horizontally (along the X direction) from the autocollimator 34 is redirected downward (in the Z direction) by 90° by the optical path repeater 36 and is irradiated toward the holding surface 14a of the holding unit 6 located below. In this way, the measurement light L is irradiated onto the holding surface 14a as the object to be measured, or onto the surface of the workpiece 4 as the object to be measured held on the holding surface 14a.

[0069] A portion of the measurement light L irradiated onto the object to be measured is reflected by the surface of the object to travel upward, enters the optical path repeater 36, is reflected by the second reflecting surface 36b and the first reflecting surface 36a, changes its angle by 90°, and enters the measurement window of the autocollimator 34. The autocollimator 34 receives the incident measurement light L with an image sensor and measures the angle formed by the surface of the object to be measured based on the light-receiving position. The measured angle value is input to the controller 50 as a numerical signal.

[0070] This measurement is performed, for example, by the controller 50 moving the optical path repeater 36 in the X direction. The autocollimator 34, which is both a light source and a measuring device, does not move; instead, the optical path repeater 36 moves on the optical path of the measurement light L emitted from the autocollimator 34 along the X direction, and the measurement light L is irradiated onto the measurement object via the optical path repeater 36. In this way, the surface of the measurement object is scanned.

[0071] In this measurement method, for example, the distance between the autocollimator 34 or optical path repeater 36 and the object to be measured is not measured directly, but instead the surface shape of the object to be measured is measured via the angle acquired by the autocollimator 34 as shown in Figure 2.

[0072] FIG. 2 is a conceptual diagram that schematically shows how the shape measuring unit 10 provided in the polishing apparatus 2 measures the surface shape of the measurement object.

[0073] For example, suppose that the angle formed by the surface of the measurement object is measured as θ1 by the autocollimator 34 at the measurement start point (P0 in FIG. 2). Then, it can be estimated that the height of the surface of the measurement object at position P1, a small distance D away from the measurement point, is higher than the height at position P0 by Dtanθ1. In other words, the difference between the height of the surface of the measurement object at position P1 and the height at position P0 can be expressed as follows: Δh1=Dtanθ1

[0074] Furthermore, if the angle of the surface of the measurement object is measured at position P1 in the same way, and the angle at that position is θ2, then the height of the surface of the measurement object at position P2, a further distance D away, can be estimated to be D tan θ2 higher than the height at position P1, and D tan θ1 + D tan θ2 higher than the height at position P0.

[0075] In this way, the angle of the measurement object at each position is measured while the optical path repeater 36 is moved by a distance D in the X direction, and the surface shape of the measurement object is measured in the form of a height distribution on the surface of the measurement object, as shown in Figure 2. n The height H relative to the position P0 at n can be expressed as follows: H n =Δh1+Δh2+……+Δh n =Dtanθ1+Dtanθ2+……+Dtanθ n

[0076] If this measurement is performed, for example, without moving the holding unit 6, but by moving the optical path repeater 36 relative to the holding unit 6 along the X direction (along a direction parallel to the holding surface 14a), it is possible to obtain the surface shape of the object to be measured (the suction plate 14 of the holding unit 6 or the workpiece 4 held thereon) along one cross section (a cross section parallel to the moving direction of the optical path repeater 36 and the irradiation direction of the measurement light L from the optical path repeater 36 to the object to be measured).

[0077] Alternatively, if the holding unit 6 is configured to rotate around an axis (axis along the Z direction) perpendicular to the holding surface 14a, the above measurement can be performed while moving the optical path repeater 36 along the X direction and rotating the holding unit 6, thereby obtaining a height distribution such as that shown in Fig. 2 as a height distribution along a spiral line set on the surface of the object to be measured. If this is performed for a sufficiently high density of measurement points, the surface shape of the target area on the object to be measured can be grasped as a two-dimensional height distribution.

[0078] Here, for example, if the object to be measured is a porous suction plate 14, if the spot diameter of the measurement light L is too small, the shape of the pores exposed on the surface of the suction plate 14 may significantly affect the value of the measured angle. Therefore, when measuring the surface shape of an article such as a porous suction plate provided on a chuck table, the shape of the measurement light L irradiated onto the surface of the suction plate to be measured is set to, for example, around 100 μm so that the microstructure of the surface does not significantly affect the acquisition of the surface shape to be measured.

[0079] In this way, the spot diameter of the measurement light L may be adjusted appropriately depending on the scale of the surface shape to be grasped and the surface condition of the object to be measured.

[0080] As described above, the shape measurement unit 10 of this embodiment measures the surface shape by relaying the measurement light L emitted from the autocollimator 34 using the optical path repeater 36 and irradiating it onto the object to be measured, and measuring the angle of the surface of the object to be measured.

[0081] Here, the autocollimator 34, which is both a light source and a measuring device, does not move, and instead the optical path repeater 36 moves to scan the surface of the object to be measured, thereby reducing the possibility that the autocollimator 34 will vibrate as it moves, which could become a cause of measurement errors.

[0082] Regarding the optical path repeater 36 that relays the measurement light L, vibrations may occur as the optical path repeater 36 moves. However, the optical path repeater 36 is a device that changes the angle of the measurement light L by reflecting the measurement light L using the mechanism of the first and second reflecting surfaces 36a, 36b described above. As long as the angle between the first and second reflecting surfaces 36a, 36b is constant, the angle between the light incident on one of the first and second reflecting surfaces 36a, 36b and the light reflected by one and the other and emitted from the other is constant. Therefore, even if the optical path repeater 36 rotates around an axis along the Y direction due to vibration, the angle of the light irradiated onto the measurement object is not affected.

[0083] Furthermore, since the autocollimator 34 is a device that measures the angle of the surface of the object to be measured regardless of the distance between the autocollimator 34 and the object to be measured, even if the optical path length of the measurement light L fluctuates due to vibration of the optical path repeater 36, there is no need to worry about the measured angle value being directly affected by this.

[0084] Of course, the irradiation position of the measurement light L on the measurement object may shift due to rotation caused by vibration of the optical path repeater 36, or positional deviation in the up-down (Z direction), front-back (Y direction), or left-right (X direction). However, the autocollimator 34 is a device that measures the angle of the measurement object, not the distance to the measurement object, and the measurement unit 50a of the controller 50 integrates the distance based on the angle to obtain the surface shape as shown in Fig. 2. Therefore, even if the irradiation position of the measurement light L shifts slightly, the angle of the surface near the target measurement position is simply measured as the surface angle at the target measurement position, and it is considered unlikely that an extremely large error will occur in the obtained surface shape as a result.

[0085] In theory, surface shape measurement using the autocollimator and optical path repeater described above can be performed even if the angle of change of light in the optical path repeater (the angle between the incident light and the outgoing light) is not 90°.

[0086] For example, if the light deflection angle in the optical path repeater is 45°, the measurement light is emitted from the autocollimator so that it forms an angle of 45° with respect to the holding surface of the holding unit, and the direction of the measurement light is changed by 45° by the optical path repeater and irradiated onto the measurement object directly below, thereby similarly measuring the angle formed by each part of the surface of the measurement object. The optical path repeater is moved along the direction of the measurement light emitted from the autocollimator (at an angle of 45° with respect to the plane formed by the holding surface).

[0087] However, doing so makes it cumbersome to adjust the angle of the autocollimator and the position of the optical path repeater, and also makes it difficult to arrange the layout of each device (measurement unit, holding unit, processing unit, etc.) relative to one another (moving the optical path repeater increases the likelihood of interference with other devices). Therefore, it is most suitable for the light deflection angle of the optical path repeater to be 90°, as described above. An optical path repeater with a 90° deflection angle is also convenient because commercially available pentaprisms and pentamirrors can be used as is as an optical path repeater with a 90° deflection angle.

[0088] When the object to be measured is the suction plate 14 of the holding unit 6 and the purpose of measuring the surface shape is to grasp the state of the upper surface (holding surface) 14a of the suction plate 14, the memory of the controller 50 stores, for example, judgment data to be compared with the measurement data of the surface shape by the shape measurement unit 10.

[0089] The data for determination is, for example, height distribution data such as that shown in Fig. 2. Alternatively, the data for determination is a table or the like that associates feature amounts extracted from such data with the content of determination for each feature amount.

[0090] When the measuring section 50a of the controller 50 acquires measurement data of the surface shape of the suction plate 14 using the shape measuring unit 10, the determining section 50b compares the acquired data with the data for determination and makes a determination. If it is determined that the state of the surface shape is not normal based on the acquired data (for example, the unevenness is smaller than the reference value and clogging occurs, the unevenness is larger than the reference value and the surface state is rough, or foreign matter is found on the surface), an alarm is issued from the notifying section 52.

[0091] Upon receiving the alarm, the operator takes necessary measures, such as self-grinding, replacing, or cleaning the suction plate 14.

[0092] Fig. 3 is a front view showing how the surface shape of the polishing pad 20 is measured in the processing apparatus of Fig. 1. When the polishing pad 20 is the measurement object, for example, as shown in Fig. 3, the optical path relay 36 is rotated 180° about the X axis, the direction of the measurement light L emitted from the autocollimator 34 along the X direction is changed to an upward direction, and the measurement light L is irradiated toward the polishing pad 20 to perform measurement.

[0093] The polishing pad 20 becomes worn, rough, clogged, etc. with use. Therefore, it is effective to measure the surface shape of the polishing surface at the lower end of the polishing pad 20 in order to determine whether the polishing pad 20 needs to be replaced, dressed, trued, etc.

[0094] The surface shape of the polishing pad 20 can be measured in the same manner as described above (see FIG. 2). At this time, for example, by performing the above measurement while moving the optical path relay 36 along the X direction (in a direction parallel to the polishing surface of the polishing pad 20) and rotating the polishing pad 20, the height distribution shown in FIG. 2 can be obtained as a height distribution along a spiral line set on the surface of the measurement object.

[0095] The structures, methods, etc. according to the above-described embodiments are not limited to the above-described embodiments, and may be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0096] 2: Processing equipment (polishing equipment), 4: Workpiece, 6: Holding unit 8: Processing unit (polishing unit), 10: Shape measurement unit 12: table base, 14: suction plate, 14a: holding surface (upper surface) 16: Spindle housing, 18: Spindle 20: Pad, 20a: Pad base, 20b: Polishing layer, 22: Mount 24: Z-axis movement mechanism, 26: guide rail, 28: moving table 30: ball screw, 32: rotation drive source 34: autocollimator, 36: optical path repeater, 36a: first reflecting surface, 36b: second reflecting surface 38: X-axis moving mechanism, 40: guide rail, 42: moving table 44: Ball screw, 46: Rotation drive source 48: Support member 50: Controller, 50a: Measurement unit, 50b: Determination unit, 52: Notification unit L: Measuring light

Claims

1. a holding unit having a holding surface for holding a workpiece; a processing unit that processes the workpiece held by the holding unit; a shape measuring unit for measuring the surface shape of the measurement object, The shape measurement unit comprises: an autocollimator that emits measurement light, receives the measurement light reflected from the surface of the measurement object, and measures the angle of the surface of the measurement object at the position where the measurement light is irradiated; an optical path repeater that receives the measurement light emitted from the autocollimator, changes the direction of the measurement light by a predetermined angle, and irradiates the measurement light on the surface of the measurement object, and receives the measurement light reflected from the surface of the measurement object, changes the direction of the measurement light by the predetermined angle, and guides the measurement light to the autocollimator; A processing device equipped with the above.

2. The optical path repeater is configured to be movable, a controller that controls the light source to irradiate the measurement light from the autocollimator through the light path repeater to the surface of the object to be measured while moving the light path repeater; The processing device according to claim 1 .

3. The optical path repeater is configured to be movable along a direction parallel to the holding surface of the holding unit, and the holding unit is configured to be rotatable about an axis intersecting the holding surface; a controller that controls the movement of the optical path repeater while rotating the holding unit, and the irradiation of measurement light from the autocollimator to the holding surface via the optical path repeater; The processing device according to claim 1 .

4. the processing unit includes a polishing pad that polishes the holding surface of the holding unit or the workpiece held on the holding surface; The shape measuring unit is configured to measure the surface shape of the polishing pad as the measurement object. The processing device according to claim 1 .

5. The processing unit includes a spindle to which the polishing pad is attached and which rotates together with the polishing pad; the optical path relay is configured to be movable along a direction parallel to the polishing surface of the polishing pad; a controller that controls the movement of the optical path repeater while rotating the spindle, and the irradiation of measurement light from the autocollimator to the polishing surface of the polishing pad via the optical path repeater; The processing device according to claim 4.

6. a determination unit that determines the surface shape of the measurement object measured by the shape measurement unit; and a notification unit that issues an alarm in response to the result of the determination by the determination unit. The processing device according to any one of claims 1 to 5.

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