Polishing device

Abstract

To provide a polishing device which can improve accuracy of a position coordinate associated with a film thickness measured value.SOLUTION: A polishing device includes: a pad thickness measuring device which measures thickness of a polishing pad 1; and an optical type film thickness measuring device 30 which obliquely irradiates a substrate with light and determines a film thickness measured value of a measuring point; and a control device 50 which associates the film thickness measured value with a measuring coordinate indicating the position of a measuring point. Movement amount of the measuring coordinate corresponding to the measured value of thickness of the polishing pad 1 is determined on the basis of correlation data showing a relation between thickness of the polishing pad and movement amount of the measuring coordinate and the measuring coordinate associated with the film thickness measured value is corrected on the basis of the determined movement amount of measuring coordinate.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The manufacturing process of semiconductor devices includes a process of polishing a wafer to flatten its surface. A polishing apparatus that performs chemical mechanical polishing (CMP) is known as one method of polishing a wafer. The polishing apparatus presses the wafer against the polishing surface while supplying a polishing liquid to the polishing surface of a polishing pad supported on a polishing table, and further moves the wafer and the polishing table relative to each other. In this manner, the surface of the wafer is polished.

[0003] The polishing performance of a polishing pad decreases each time a wafer is polished. Therefore, the polishing apparatus performs dressing to restore the polishing performance of the polishing pad. In dressing, the polishing surface of the polishing pad is scraped off with a dresser to which hard abrasive grains such as diamond particles are fixed. In this way, the polishing surface of the polishing pad is regenerated (in other words, the polishing performance of the polishing pad is restored).

[0004] In general, a polishing apparatus is equipped with a film thickness measuring device for measuring the film thickness on the surface of the wafer during polishing. The polishing apparatus ends polishing when the measured film thickness reaches a predetermined target value (in other words, the polishing end point). An example is an optical film thickness measuring device. The optical film thickness measuring device has an optical sensor head 35. The optical sensor head 35 directs light to a measurement point on the surface of the wafer and receives reflected light from the surface of the wafer. The measured film thickness is determined by an analysis based on this reflected light. When the optical sensor head 35 is scanned across the surface of the wafer, film thickness measurements are obtained at multiple measurement points on the surface of the wafer. The measured film thickness is associated with position coordinates (measurement coordinates) that indicate the measurement position on the surface of the wafer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5167010 Summary of the Invention [Problem to be solved by the invention]

[0006] The polishing pad is worn down by polishing or dressing, and the thickness of the polishing pad gradually decreases. The more the thickness of the polishing pad decreases, the closer the surface of the wafer pressed against the polishing pad approaches the sensor head. As a result, the position of the measurement point by the sensor head may shift before and after the thickness of the polishing pad changes. As a result, the position coordinates associated with the film thickness measurement value will erroneously indicate the shifted position.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a polishing apparatus capable of improving the accuracy of position coordinates associated with film thickness measurement values. [Means for solving the problem]

[0008] In one aspect, a polishing apparatus is provided that includes a polishing table that rotates while supporting a polishing pad, a polishing head that presses a substrate against the polishing surface of the polishing pad, a pad thickness measuring device that measures the thickness of the polishing pad, an optical film thickness measuring device that irradiates light obliquely to multiple measurement points on the substrate, receives reflected light from the substrate, and determines film thickness measurement values ​​at the measurement points based on the reflected light, and a control device that associates measurement coordinates indicating the positions of the measurement points with the film thickness measurement values, wherein the control device performs calculations based on correlation data that indicates the relationship between the thickness of the polishing pad and the amount of movement of the measurement coordinates, thereby determining the amount of movement of the measurement coordinates corresponding to the measured thickness of the polishing pad, and includes a calculation device that corrects the measurement coordinates associated with the film thickness measurement values ​​based on the determined amount of movement of the measurement coordinates.

[0009] In one aspect, the polishing pad thickness measuring device is configured to measure the thickness of the polishing pad by contacting the polishing surface of the polishing pad. In one aspect, the polishing pad thickness measuring device is disposed within the polishing table and configured to measure the thickness of the polishing pad based on the height of a surface of the substrate contacting the polishing surface. In one aspect, the optical film thickness measuring device includes an optical sensor head that projects and receives light between the substrate and the polishing pad thickness measuring device, and the polishing pad thickness measuring device is configured to measure the thickness of the polishing pad based on the height of the surface of the substrate when the polishing pad thickness measuring device is covered together with the optical sensor head by the substrate pressed against the polishing pad. In one embodiment, the optical film thickness measurement device includes a light projecting optical fiber that irradiates light obliquely onto a substrate, and a light receiving optical fiber that receives light that is obliquely reflected by the substrate, and the diameter of the light projecting optical fiber and the diameter of the light receiving optical fiber are configured to be different sizes.

[0010] In one aspect, a polishing apparatus is provided that includes a polishing table that rotates while supporting a polishing pad, a polishing head that presses a substrate against the polishing surface of the polishing pad, an optical film thickness measurement device that irradiates light obliquely to multiple measurement points on the substrate, receives light reflected from the substrate, and determines film thickness measurement values ​​at the measurement points based on the reflected light and determines the amount of received light, and a control device that associates measurement coordinates indicating the positions of the measurement points with the film thickness measurement values, wherein the control device performs calculations based on first correlation data indicating the relationship between the amount of received light and the thickness of the polishing pad and second correlation data indicating the relationship between the thickness of the polishing pad and the amount of movement of the measurement coordinates, thereby determining the thickness of the polishing pad corresponding to the amount of received light, determining the amount of movement of the measurement coordinates corresponding to the determined measurement value of the thickness of the polishing pad, and comprising a calculation device that corrects the measurement coordinates associated with the film thickness measurement values ​​based on the determined amount of movement of the measurement coordinates.

[0011] In one aspect, a polishing apparatus is provided that includes a polishing table that rotates while supporting a polishing pad, a polishing head that presses a substrate against the polishing surface of the polishing pad, an optical film thickness measurement device that irradiates light obliquely to multiple measurement points on the substrate, receives reflected light from the substrate, and determines film thickness measurement values ​​at the measurement points based on the reflected light and determines the amount of received light, and a control device that associates measurement coordinates that indicate the positions of the measurement points with the film thickness measurement values, wherein the control device performs calculations based on correlation data that indicates the relationship between the amount of received light and the amount of movement of the measurement coordinates, thereby determining the amount of movement of the measurement coordinates that corresponds to the amount of received light, and a calculation device that corrects the measurement coordinates associated with the film thickness measurement values ​​based on the determined amount of movement of the measurement coordinates. Effect of the Invention

[0012] The control device is configured to determine the amount of movement of the measurement point by utilizing a correlation based on the thickness of the polishing pad, thereby correcting the position coordinates corresponding to the film thickness measurement value of the substrate. Therefore, the polishing apparatus can improve the accuracy of the position coordinates corresponding to the film thickness measurement value. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a polishing apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a top view showing the positional relationship between the wafer and the polishing table during polishing. [Diagram 3] 3 is an enlarged view showing a light path from a light-projecting optical fiber (light-projecting section) to a light-receiving optical fiber (light-receiving section). FIG. [Figure 4] 1 shows an example of a plurality of measurement points on the surface of a wafer W. [Diagram 5] FIG. 4 is a diagram showing an example of a film thickness distribution. [Figure 6] 4 is a flowchart showing the operation of the polishing apparatus of the first embodiment. [Figure 7] FIG. 4 is a diagram showing a modified example of the polishing apparatus of the first embodiment. [Figure 8] FIG. 11 is a diagram showing the relationship between the thickness of a polishing pad and the amount of received light in a second embodiment. [Figure 9] 10 is a flowchart showing the operation of a polishing apparatus according to a second embodiment. [Figure 10] 10 is a flowchart showing the operation of a polishing apparatus according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment) FIG. 1 is a diagram showing an embodiment of a polishing apparatus. The polishing apparatus shown in FIG. 1 is an apparatus for chemically and mechanically polishing a workpiece such as a wafer, a substrate, or a panel, and an example of polishing a wafer will be described below. The polishing apparatus includes a polishing pad 1, a polishing table 3 for supporting the polishing pad 1, a polishing liquid supply nozzle 40 for supplying a polishing liquid (e.g., a slurry containing abrasive grains) onto the polishing pad 1, a polishing head 10 for holding and pressing a wafer W against the polishing pad 1, a dressing unit 20 for dressing (conditioning) the polishing surface 1a of the polishing pad 1, an optical film thickness measuring device 30 for measuring the film thickness on the surface of the wafer W, and a control device 50 for controlling the operation of these components.

[0015] The polishing pad 1 is attached to the upper surface of the polishing table 3. The upper surface of the polishing pad 1 constitutes a polishing surface 1a for polishing the wafer W. The polishing pad 1 has a thickness. Hereinafter, the distance from the upper surface (polishing surface 1a) of the polishing pad 1 to the lower surface (the surface attached to the upper surface of the polishing table 3) is referred to as the thickness of the polishing pad 1. A through hole 1b is formed in the polishing pad 1. A hole 7 is formed in the upper surface of the polishing table 3. The through hole 1b and the hole 7 are in communication. As described below, the through hole 1b passes light for film thickness measurement.

[0016] The polishing table 3 is connected to a table motor 5 via a table shaft 3a. The table motor 5 is configured to rotate the polishing table 3. The polishing table 3 is rotated about its axis by the table motor 5. The polishing pad 1 rotates integrally with the polishing table 3. For example, the polishing table 3 rotates in the direction indicated by the arrow in FIG. 1.

[0017] The polishing head 10 is connected to a polishing head motor (not shown) via a polishing head shaft 12. The polishing head motor is configured to rotate the polishing head 10. The polishing head 10 is rotated about its axis by the polishing head motor. The polishing head 10 rotates together with the polishing head shaft 12. For example, the polishing head 10 rotates in the direction indicated by the arrow in FIG. 1.

[0018] The lower surface of the polishing head 10 is configured to hold the wafer W. A vacuum source (not shown) that vacuum-sucks the wafer W is connected to the lower surface of the polishing head 10. The wafer W is attracted and held on the lower surface of the polishing head 10 by the vacuum source. In other words, the lower surface of the polishing head 10 constitutes a wafer holding surface that holds the wafer W.

[0019] Furthermore, an airbag (not shown) is provided on the underside of the polishing head 10 to press the wafer W against the polishing surface 1a of the polishing pad 1. The airbag generates pressure to press the held wafer W. A gas supply line (not shown) is connected to the airbag, and the pressure is adjusted by the amount of gas supplied. The airbag presses the wafer W from its back side. The polishing head 10 presses the wafer W against the polishing surface 1a of the polishing pad 1 by the airbag.

[0020] The polishing head 10 is connected to a lifting cylinder (not shown) via a polishing head shaft 12. The lifting cylinder is configured to lift and lower (move up and down) the polishing head 10. The polishing head 10 moves up and down relative to the polishing pad 1 by the lifting cylinder. The polishing head 10 moves up and down integrally with the polishing head shaft 12. The lifting cylinder lowers the polishing head 10 holding the wafer W toward the polishing pad 1, thereby bringing the surface of the wafer W (in other words, the surface to be polished) into contact with the polishing surface 1a of the polishing pad 1. The lifting cylinder may further lower the polishing head 10 to press the surface of the wafer W against the polishing surface 1a of the polishing pad 1.

[0021] The dressing unit 20 includes a dresser 21, a dresser shaft 23 connected to the dresser 21, a support block 25 rotatably supporting the dresser shaft 23, an air cylinder 26 for pressing the dresser 21 against the polishing pad 1, a dresser arm 27 rotatably supporting the dresser shaft 23, and a support shaft 28 for supporting the dresser arm 27. The lower surface of the dresser 21 constitutes a dressing surface to which abrasive grains such as diamond particles are fixed. As described later, the dresser 21 comes into contact with the polishing surface 1a of the polishing pad 1.

[0022] The dresser 21 is connected to a dresser motor (not shown) installed in the dresser motor via a dresser shaft 23. The dresser motor is configured to rotate the dresser 21. The dresser 21 is rotated around its axis by the dresser motor. The dresser 21 rotates integrally with the dresser shaft 23. For example, the dresser 21 rotates in the direction indicated by the arrow in FIG. 1.

[0023] The dresser 21 is connected to a support block 25 via a dresser shaft 23. The support block 25 is connected to an air cylinder 26. The air cylinder 26 is configured to raise and lower the dresser. The dresser 21 moves up and down relative to the polishing pad 1 by the air cylinder 26. The air cylinder 26 moves up and down integrally with the dresser shaft 23 and the support block 25. The air cylinder 26 lowers the dresser 21 toward the polishing pad 1, thereby pressing the dressing surface against the polishing surface 1a of the polishing pad 1.

[0024] The support shaft 28 is connected to a motor (not shown), and the motor is configured to rotate the support shaft 28. The support shaft 28 is rotated about its axis by the motor. The dresser 21, the dresser shaft 23, and the dresser arm 27 swing integrally around the support shaft 28 as a result of the rotation of the support shaft 28.

[0025] The control device 50 is composed of at least one computer. The control device 50 includes a storage device 50a in which a program is stored, and a calculation device 50b that executes calculations according to instructions included in the program. The storage device 50a includes a main storage device such as a RAM, and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Examples of the calculation device 50b include a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). However, the specific configuration of the control device 50 is not limited to these examples.

[0026] The wafer W is polished as follows. The polishing head 10 holds the wafer W with the surface (surface to be polished) of the wafer W facing the polishing pad 1. While the polishing table 3 is rotated by the table motor 5, a polishing liquid is supplied from the polishing liquid supply nozzle 10 onto the polishing surface 1a of the polishing pad 1. In this state, the polishing head 10 is lowered by the polishing head lifting mechanism while being rotated by the polishing head motor. As a result, the surface of the wafer W comes into contact with the polishing surface 1a of the polishing pad 1. Furthermore, the polishing head 10 presses the wafer W against the polishing pad 1. The surface of the wafer W is polished by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid and the polishing surface 1a.

[0027] The dressing of the polishing surface 1a of the polishing pad 1 is performed as follows. While the polishing table 3 is rotated by the table motor 5, pure water is supplied onto the polishing surface 1a of the polishing pad 1 from a pure water supply nozzle (not shown). In this state, the dresser 21 is lowered by the air cylinder 26 while being rotated by the dresser motor. As a result, the dressing surface of the dresser 21 contacts the polishing surface 1a of the polishing pad 1. The dressing surface of the dresser 21 presses the polishing surface 1a of the polishing pad 1 by the air cylinder 26. Furthermore, the dresser 21 is swung and moves in parallel on the polishing surface 1a of the polishing pad 1. In this way, the polishing pad 1 is scraped off by the dresser 21, and the polishing surface 1a is dressed (regenerated). In other words, the polishing performance of the polishing pad 1 is restored by the dressing. The dressing of the polishing surface 1a of the polishing pad 1 is performed during or after the polishing of the wafer W.

[0028] The optical film thickness measuring device 30 includes a light source 31, an optical sensor head 35 arranged inside the polishing table 3, and a spectroscope 37. The light source 31, the optical sensor head 35, and the spectroscope 37 are attached to the polishing table 3 and rotate integrally with the polishing table 3 and the polishing pad 1. The optical sensor head 35 is optically connected to the light source 31 and the spectroscope 37. The light source 31 and the spectroscope 37 are connected to a control device 50.

[0029] The optical sensor head 35 includes a light projecting section 32 and a light receiving section 33. For example, the light projecting section 32 and the light receiving section 33 are each formed of an optical fiber cable. The light projecting section 32 may be called a light projecting optical fiber 32, and the light receiving section 33 may be called a light receiving optical fiber 33. One end (tip) of the light projecting section 32 and one end (tip) of the light receiving section 33 are directed upward and face the wafer W to be polished as described below. One end of the light projecting section 32 and one end of the light receiving section 33 are inclined in a direction approaching each other. The other end of the light projecting section 32 is optically connected to the light source 31, and the other end of the light receiving section 34 is optically connected to the spectroscope 37.

[0030] The light source 31 may be a light emitting diode (LED), a halogen lamp, a xenon lamp, or the like. The optical sensor head 35 causes light from the light source 31 to be incident on the surface of the wafer W and receives the light reflected by the surface of the wafer W. Specifically, the light projecting unit 32 guides the light from the light source 31 to be incident on the surface of the wafer W, and the light receiving unit 33 receives the reflected light from the surface of the wafer W. The spectroscope 37 generates a spectrum by decomposing the reflected light received by the light receiving unit 33 according to wavelength and measuring the intensity of the reflected light at each wavelength. The control device 50 determines the film thickness of the wafer W based on the spectrum. As a result, a film thickness measurement value is obtained. The control device 50 determines that the polishing end point has been reached when the film thickness measurement value reaches a predetermined target value.

[0031] The optical sensor head 35 is disposed inside the hole 7 of the polishing table 3. It is sufficient that the optical sensor head 35 is disposed below the polishing surface 1a of the polishing pad 1. In other words, it is sufficient that one end of the light-projecting unit 32 and one end of the light-receiving unit 33 are disposed below the polishing surface 1a of the polishing pad 1. As shown in FIG. 1, one end of the light-projecting unit 32 and one end of the light-receiving unit 33 are disposed below the upper surface of the polishing table 3. One end of the light-projecting unit 32 and one end of the light-receiving unit 33 may be disposed inside the through-hole 1b as long as they are below the polishing surface 1a of the polishing pad 1.

[0032] Through hole 1b and hole 7 are filled with liquid (e.g., pure water) as a medium that transmits light. In other words, the space between the surface of wafer W to be polished and optical sensor head 35 (particularly, one end of light projector 32 and one end of light receiver 33) is filled with liquid. Therefore, the light incident on the surface of wafer W from light projector 32 and the light reflected from the surface of wafer W to light receiver 33 pass through the liquid. This liquid is supplied by a liquid supply line (not shown) connected to hole 7 and is discharged by a liquid discharge line (not shown) connected to hole 7.

[0033] The medium through which light passes may be air instead of a liquid. A transparent window (not shown) may be provided instead of a liquid through which light passes. The window may be provided inside the through hole 1b or inside the hole 7, as long as it is located below the polishing surface 1a of the polishing pad 1 and above the optical sensor head 35 (tips of the light projector 32 and the light receiver 33). In this case, the window is provided so as to close at least one of the through hole 1b and the hole 7.

[0034] FIG. 2 is a top view showing the positional relationship between the wafer W and the polishing table 3 during polishing. The optical sensor head 35 crosses (in other words, passes) the wafer W along a trajectory shown by a dotted line in FIG. 2 every time the polishing table 3 rotates once. The optical sensor head 35 is disposed at a predetermined distance from the center of the polishing table 3 in the radial direction of the polishing table 3. The center of the wafer W is disposed at a predetermined distance from the center of the polishing table 3 in the radial direction of the polishing table 3. In FIG. 2, the distance from the center of the polishing table 3 to the optical sensor head 35 is equal to the distance from the center of the polishing table 3 to the center of the wafer W. Therefore, in FIG. 2, the optical sensor head 35 crosses the center of the wafer W as the polishing table 3 rotates.

[0035] 2 shows an example in which the optical sensor head 35 crosses the center of the wafer W, but the arrangement of the optical sensor head 35 is not limited to this. The optical sensor head 35 only needs to cross below the wafer W.

[0036] The optical sensor head 35 intermittently irradiates the surface of the wafer W with light at predetermined time intervals while moving below the wafer W. Specifically, the control device 50 controls the light source 31 to cause the light source 31 to emit light intermittently at predetermined time intervals. The light from the light source 31 is irradiated intermittently at predetermined time intervals onto the surface of the wafer W via the light projecting unit 32. As a result, the light is irradiated onto a plurality of points on the surface of the wafer W, and the film thickness at each point is measured.

[0037] The optical sensor head 35 may measure the film thickness by continuing to irradiate the surface of the wafer W with light while moving below the wafer W. In other words, the optical sensor head 35 may continuously irradiate the surface of the wafer W with light. In this case, the control device 50 controls the light source 31 to maintain light emission while the optical sensor head 35 moves below the wafer W. The light from the light source 31 continues to be irradiated onto the surface of the wafer W via the light projector 32. The spectroscope 12 generates a spectrum at a predetermined time interval. As a result, the film thickness at each location is measured by analyzing the spectrum obtained at the predetermined time interval.

[0038] Hereinafter, the point on the surface of the wafer W where the light is irradiated will be referred to as the "measurement point." Also, the time interval for performing the film thickness measurement will be referred to as the "measurement interval." In particular, when the optical sensor head 35 irradiates light intermittently, the time interval for irradiating the light will be referred to as the measurement interval, and when the optical sensor head 35 irradiates light continuously, the predetermined time interval for the spectroscope 37 to generate a spectrum will be referred to as the measurement interval.

[0039] The control device 50 associates the film thickness measurement value of a measurement point with a measurement coordinate indicating the position of the measurement point. The measurement coordinate is a coordinate (position coordinate) indicating a position on the surface of the wafer W. For example, the measurement coordinate is indicated as a radial position on the wafer W. The control device 50 associates the film thickness measurement value of each measurement point with the measurement coordinate every time the optical sensor head 35 passes over the wafer W. In this manner, the film thickness distribution is generated based on the film thickness measurement values ​​and the measurement coordinates at a plurality of measurement points. For example, the film thickness distribution is generated by the control device 50.

[0040] The film thickness distribution is a distribution of film thickness measurement values ​​for each measurement coordinate. The film thickness measurement value at each measurement coordinate may be expressed as an average value of the film thickness measurement values ​​at that measurement coordinate. For example, the measurement coordinates can be expressed as positions on the diameter of the wafer W. In this case, the film thickness distribution can be expressed as a film thickness distribution on the diameter of the wafer W. For example, the measurement coordinates can be expressed as positions on the radius of the wafer W. In this case, the film thickness distribution can be expressed as a film thickness distribution on the radius of the wafer W.

[0041] The measurement coordinates are determined as follows, for example. The control device 50 is connected to the table motor 5. The control device 50 receives information on the rotation of the polishing table 3 from the table motor 5. The control device 50 determines that the optical sensor head 35 is moving below the wafer W when the polishing table 3 is within a range of a predetermined rotation angle set in advance. Based on the determination, the control device 50 causes the optical film thickness measuring device 30 to perform film thickness measurement at a predetermined measurement interval. Furthermore, based on the determination, the control device 50 detects the rotation speed (or angular velocity) of the polishing table 3 during the film thickness measurement. Based on the detected rotation speed, the control device 50 determines the rotation angle at a predetermined time. As a result, the control device 50 determines the position of the optical sensor head 35 at the predetermined time based on the rotation angle. Furthermore, the control device 50 determines the position of the measurement point, i.e., the measurement coordinates, based on the determined position of the optical sensor head 35 and the measurement interval. In this way, the control device 50 associates the measurement coordinates with the film thickness measurement value at the predetermined measurement point.

[0042] The range of the predetermined rotation angle for determining that the optical sensor head 35 is passing under the wafer W can be set in advance based on the position and size of the wafer W. The measurement coordinates may be determined by a method other than the above.

[0043] Fig. 3 is an enlarged view showing the path of light from the light projecting optical fiber (light projecting section) 32 to the light receiving optical fiber (light receiving section) 33. As shown in Fig. 3, the tip of the light projecting optical fiber 32 and the tip of the light receiving optical fiber 33 are inclined at a predetermined angle with respect to the surface of the wafer W. The incident angle refers to the angle between the incident light and the normal to the wafer W at the point where the light is irradiated, i.e., the measurement point, and the reflection angle refers to the angle between the reflected light and the normal to the wafer W at the measurement point.

[0044] Here, the wafer W may have a laminated structure in which films and wiring structures made of various materials are laminated from the inside to the surface of the wafer W. When light for film thickness measurement is irradiated vertically onto such a wafer W, the light may pass through the film of the top layer of the wafer W (i.e., the layer on the most surface side of the wafer W). As a result, the incident light is reflected by an inner layer deeper than the top layer. In this case, the acquired spectrum contains not only information on the top layer of the wafer W, but also information on the inner layers of the wafer W for the number of layers through which the light has passed. As a result, when light for film thickness measurement is irradiated vertically onto the surface of the wafer W, it may be difficult to obtain a film thickness measurement value with high accuracy for the top layer of the wafer W.

[0045] In order to obtain more accurate film thickness measurements for the top layer of wafer W, light projecting optical fiber 32 may be positioned at an angle as described above.

[0046] The tip of the light-receiving optical fiber 33 is inclined at an angle at which it can receive the reflected light. However, it is preferable that the light-receiving optical fiber 33 receives light at an angle substantially equal to the angle of reflection of the light on the surface of the wafer W. In other words, it is preferable that the tip of the light-receiving optical fiber 33 is inclined so that the reflected light enters substantially perpendicularly to the tip of the light-receiving optical fiber 33. In this case, as shown in FIG. 3, the tip of the light-projecting optical fiber 32 and the tip of the light-receiving optical fiber 33 are inclined at the same angle in directions facing each other.

[0047] Incidentally, the thickness of the polishing pad 1 is worn away by polishing the wafer W and dressing the polishing surface 1a, and gradually becomes thinner. In other words, the thickness of the polishing pad 1 gradually decreases. As the thickness of the polishing pad 1 becomes thinner, the surface of the wafer W pressed against the polishing pad 1 approaches the light projecting optical fiber 32 and the light receiving optical fiber 33 (i.e., the optical sensor head 35). As described above, the light projecting optical fiber 32 makes the light incident obliquely onto the wafer W. Therefore, when the light path between the light projecting optical fiber 32 and the measurement point becomes shorter, the position of the measurement point shifts in the in-plane direction of the wafer W as shown in FIG. 3. That is, the position of the measurement point is different before and after the thickness of the polishing pad 1 is reduced. As a result, the path of the reflected light changes due to the positional shift of the measurement point, and the light receiving optical fiber 33 may not be able to receive the reflected light.

[0048] Therefore, in order to enable the light-receiving optical fiber 33 to receive the reflected light even if the position of the measurement point is shifted, the tip of the light-projecting optical fiber 32 has a large diameter that can tolerate the positional shift of the measurement point. For example, as shown in Fig. 3, the diameter of the light-projecting optical fiber 32 is larger than the diameter of the light-receiving optical fiber 33. This allows the light-receiving optical fiber 33 to receive the reflected light even if the position of the measurement point is shifted as the thickness of the polishing pad 1 decreases.

[0049] Although not shown, the tip of the light-receiving optical fiber 33 may have a large diameter to the extent that it can tolerate misalignment of the measurement point. In this case, the diameter of the light-receiving optical fiber 33 is larger than the diameter of the light-projecting optical fiber 32. In this case as well, the light-receiving optical fiber 33 can receive reflected light even if the position of the measurement point is misaligned.

[0050] FIG. 4 is a diagram showing an example of a plurality of measurement points on the surface of the wafer W. FIG. 4 shows a plurality of measurement points before the thickness of the polishing pad 1 is reduced (before the polishing pad 1 is worn out) and a plurality of measurement points after the thickness of the polishing pad 1 is reduced (after the polishing pad 1 is worn out). As shown in FIG. 4, when the thickness of the polishing pad 1 is reduced, a position shift occurs at each measurement point. Therefore, even if film thickness measurements are performed under the same measurement conditions before and after the thickness of the polishing pad 1 is reduced, different points on the surface of the wafer W are measured. If the position shift of the measurement points is not reflected in the measurement coordinates, the measurement coordinates associated with the film thickness measurement value will indicate a position different from the actual measurement coordinates.

[0051] FIG. 5 is a diagram showing an example of a film thickness distribution. FIG. 5 shows a film thickness distribution in the diameter of a wafer W as an example. The film thickness distribution shown by the solid line is a film thickness distribution generated based on multiple measurement points before the thickness of the polishing pad 1 shown in FIG. 4 is reduced (before the polishing pad 1 is worn out). The film thickness distribution shown by the dashed and dotted line is a film thickness distribution generated based on multiple measurement points after the thickness of the polishing pad 1 shown in FIG. 4 is reduced (after the polishing pad 1 is worn out). As described above, the film thickness distribution after the thickness of the polishing pad 1 is reduced shows a position where the measurement coordinates corresponding to the film thickness measurement value are different from the actual position. As a result, the film thickness distribution is shifted as a whole as shown in FIG. 5.

[0052] Therefore, in this embodiment, the measurement coordinates are corrected based on first correlation data indicating the relationship between the thickness of the polishing pad 1 and the movement amount of the measurement point. Here, the movement amount of the measurement point refers to the distance that the measurement point has moved from the initial position in the in-plane direction of the wafer W. In other words, the movement amount of the measurement point indicates the degree of positional deviation of the measurement point described above. For example, the first correlation data is stored in the storage device 50a of the control device 50. The first correlation data is obtained in advance by an experiment.

[0053] Specifically, the first correlation data includes a reference value for the thickness of the polishing pad 1, and the amount of movement of the measurement point is associated with this reference value as zero. In other words, a value indicating the initial position of the measurement point is associated with the reference value for the thickness of the polishing pad 1. The first correlation data indicates the amount of movement of the measurement point when the thickness of the polishing pad 1 varies with respect to the reference value for the thickness of the polishing pad 1, and the amount of movement of the measurement point is associated with each value indicating the thickness of the polishing pad 1.

[0054] When the thickness of the polishing pad 1 varies, the height of the polishing surface 1a also varies. Therefore, the first correlation data may be defined by the height of the polishing surface 1a instead of the thickness of the polishing pad 1. That is, the first correlation data may be represented by the relationship between the height of the polishing surface 1a and the amount of movement of the measurement point. In this case, the first correlation data indicates the amount of movement of the measurement point when the height of the polishing pad 1a varies with respect to the reference value of the height of the polishing surface 1a, and each value indicating the height of the polishing surface 1a is associated with the amount of movement of the measurement point.

[0055] The arithmetic unit 50b of the control device 50 executes calculations according to instructions included in the program, and determines the movement amount of the measurement point from the measured value of the thickness of the polishing pad 1 based on the first correlation data. The arithmetic unit 50b of the control device 50 corrects the measurement coordinates based on the determined movement amount of the measurement point. The measurement of the thickness of the polishing pad 1 will be described below.

[0056] Referring again to FIG. 1, the polishing apparatus can measure the thickness of the polishing pad 1 by using the dressing unit 20. The dressing unit 20 is provided with a first pad thickness measuring device 29 for measuring the thickness of the polishing pad 1. The first pad thickness measuring device 29 is, for example, a contact-type displacement sensor. The first pad thickness measuring device 29 is fixed to the support block 25, and a contact of the first pad thickness measuring device 29 is in contact with the dresser arm 27. Since the support block 25 can move up and down together with the dresser shaft 23 and the dresser 21, the first pad thickness measuring device 29 can move up and down together with the dresser shaft 23 and the dresser 21. On the other hand, the position of the dresser arm 27 in the vertical direction is fixed. The first pad thickness measuring device 29 moves up and down together with the dresser shaft 23 and the dresser while the contact of the first pad thickness measuring device 29 is in contact with the dresser arm 27. Therefore, the first pad thickness measuring device 29 can measure the displacement of the dresser 21 relative to the dresser arm 27 .

[0057] The first pad thickness measuring device 29 can measure the thickness of the polishing pad 1 via the dresser 21. Specifically, the first pad thickness measuring device 29 measures the height of the polishing surface 1a using the lower surface of the polishing pad 1 as a reference surface, thereby measuring the thickness of the polishing pad 1. Since the first pad thickness measuring device 29 is connected to the dresser 21 via the dresser shaft 23, the first pad thickness measuring device 29 can measure the thickness of the polishing pad 1 during dressing of the polishing pad 1. In addition, the rotation of the polishing table 3 and the rotation of the dresser 21 can be stopped, and the thickness of the polishing pad 1 can be measured while dressing is stopped.

[0058] The first pad thickness measuring device 29 may be a non-contact sensor such as a laser sensor, an ultrasonic sensor, or an eddy current sensor. Furthermore, the first pad thickness measuring device 29 may be fixed to the dresser arm 27 and arranged to measure the displacement of the support block 25. Even in this case, the first pad thickness measuring device 29 can measure the displacement of the dresser 21 relative to the dresser arm 27.

[0059] The first pad thickness measuring device 29 can also measure the distance from a preset reference plane to the polishing surface 1a as the height of the polishing surface 1a. The reference plane is a virtual plane. The first correlation data may be defined as the relationship between the height of the polishing surface 1a measured in this manner and the amount of movement of the measurement point.

[0060] The first pad thickness measuring device 29 is electrically connected to the control device 50, and the control device 50 receives an output signal from the first pad thickness measuring device 29. That is, the control device 50 can receive the measurement value of the thickness of the polishing pad 1 measured by the first pad thickness measuring device 29. Furthermore, as described above, when the height of the polishing surface 1a is measured by the first pad thickness measuring device 29, the control device 50 can receive the measurement value of the height of the polishing surface 1a.

[0061] A mechanism similar to the pad height measuring device described above may be provided on the polishing head 10 side to measure the height of the polishing surface 1a and the thickness of the polishing pad 1 through the polishing head 10.

[0062] FIG. 6 is a flowchart showing the operation of the polishing apparatus shown in FIG. 1. In step S101, the pad height measuring device of the dressing unit 20 measures the thickness of the polishing pad 1. Next, in step S102, the control device 50 determines the movement amount of the measurement point corresponding to the thickness of the polishing pad 1 from the first correlation data. Next, in step S103, the optical film thickness measuring device 30 performs film thickness measurement, and the measurement coordinates are associated with the film thickness measurement value. Next, in step S104, the control device 50 corrects the measurement coordinates associated with the film thickness measurement value by the movement amount of the measurement point determined in step S102. As a result, the measurement coordinates associated with the film thickness measurement value indicate a more accurate position. Furthermore, it is possible to suppress the film thickness distribution from being shifted as a whole as shown in FIG. 5.

[0063] 6, steps S101 and S102 are executed before step S103, but these steps may be executed simultaneously with step S103. Steps S101 and S102 may be executed after step S103.

[0064] The thickness of the polishing pad 1 and the height of the polishing surface 1a can also be measured using a polishing apparatus shown in Fig. 7. Fig. 7 shows a modified example of the polishing apparatus of this embodiment. Unless otherwise specified, the polishing apparatus in Fig. 7 has the same configuration as the polishing apparatus in Fig. 1, and therefore a duplicated description will be omitted. The following description will be given with reference to Fig. 7.

[0065] The polishing apparatus includes a second pad thickness measuring device 60. A through hole 1c is formed in the polishing pad 1. A hole 71 is formed in the upper surface of the polishing table 3. The through hole 1c and the hole 71 are in communication with each other. As described below, the through hole 1c passes light for measuring the thickness of the polishing pad 1. The second pad thickness measuring device 60 is disposed inside the polishing table 3. Specifically, the second pad thickness measuring device 60 is disposed inside the hole 71, and is disposed below the upper surface of the polishing table 3.

[0066] In FIG. 7, the dressing unit 20 does not include the support block 25 and the first pad thickness measuring device 29, but may include these components.

[0067] The second pad thickness measuring device 60 is, for example, an optical distance measuring sensor. The second pad thickness measuring device 60 measures the thickness of the polishing pad 1 by projecting light when the upper part is covered with a wafer W placed on the polishing pad 1 and receiving the reflected light returning from the wafer W. Note that, during measurement, the surface of the wafer W can be considered to be at substantially the same height as the polishing surface 1a. The second pad thickness measuring device 60 can measure the thickness of the polishing pad 1 while the wafer W is being polished.

[0068] Similar to the first pad thickness measuring device 29 described above, the second pad thickness measuring device 60 measures the height of the polishing surface 1a (more precisely, the height of the surface of the wafer W) using the underside of the polishing pad 1 as a reference plane, thereby measuring the thickness of the polishing pad 1.

[0069] The second pad thickness measuring device 60 can also measure the distance from a preset reference plane to the polishing surface 1a as the height of the polishing surface 1a. The reference plane is a virtual plane. The first correlation data may be defined as the relationship between the height of the polishing surface 1a thus measured and the amount of movement of the measurement point.

[0070] The second pad thickness measuring device 60 is electrically connected to the control device 50, and the control device 50 receives an output signal from the second pad thickness measuring device 60. That is, the control device 50 can receive the measured value of the thickness of the polishing pad 1 measured by the second pad thickness measuring device 60. Furthermore, as described above, when the height of the polishing surface 1a is measured by the second pad thickness measuring device 60, the control device 50 can receive the measured value of the height of the polishing surface 1a.

[0071] It should be noted that each step described with reference to Fig. 6 can be similarly performed in the polishing apparatus of Fig. 7. In particular, step S101 in Fig. 6 can be performed using a second pad thickness measuring device.

[0072] Here, when the optical sensor head 35 is moving below the wafer W and performing film thickness measurement, the polishing pad 1 above the optical sensor head 35 is temporarily compressed by the load from the polishing head 10. As a result, the optical sensor head 35 temporarily approaches the surface of the wafer W. In order to measure the thickness of the polishing pad 1 including the influence of the pressing load near the optical sensor head 35, the second pad thickness measuring device 60 may be disposed in a position covered by the wafer W simultaneously with the optical sensor head 35.

[0073] According to this embodiment, even if the measurement point moves from the initial position due to the variation in the thickness of the polishing pad 1, the measurement coordinates associated with the film thickness measurement value can indicate an accurate position. In other words, the accuracy of the position coordinates associated with the film thickness measurement value can be improved. In particular, when light for film thickness measurement is obliquely incident on the surface of the wafer W, the measurement point shifts in the in-plane direction of the wafer W due to the variation in the thickness of the polishing pad 1. In this embodiment, the thickness of the polishing pad 1 is measured, and the movement amount of the measurement point (the distance by which the measurement point shifts) is determined based on the relationship (first correlation data) between the thickness of the polishing pad 1 and the movement amount of the measurement point. By correcting the measurement coordinates based on the movement amount of the measurement point determined in this manner, the measurement coordinates associated with the film thickness measurement value can indicate an accurate position even if the thickness of the polishing pad 1 varies.

[0074] According to this embodiment, by irradiating light while tilting the light-projecting optical fiber 32 with respect to the surface of the wafer W, it is possible to suppress information about the inside of the wafer W contained in the obtained spectrum and emphasize information about the film on the top layer side of the wafer W.

[0075] According to this embodiment, even if the measurement point moves with a change in the thickness of the polishing pad 1, the reflected light from the measurement point can be received by the light-receiving optical fiber 33. Specifically, by making the diameter of one of the light-projecting optical fiber 32 and the light-receiving optical fiber 33 larger than the diameter of the other optical fiber, it is possible to accommodate the change in the light path caused by the movement of the measurement point.

[0076] Second embodiment In the first embodiment described above, the thickness of the polishing pad 1 is measured to determine the movement amount of the measurement point. In this embodiment, the movement amount of the measurement point is determined without measuring the thickness of the polishing pad 1. The configuration and operation of this embodiment that are not specifically described are similar to those of the first embodiment described with reference to FIGS. 1 to 7, so duplicated descriptions will be omitted. This embodiment can be implemented in either the polishing apparatus shown in FIG. 1 or the polishing apparatus shown in FIG. 7.

[0077] As described in the first embodiment, when the thickness of the polishing pad 1 is reduced, the optical path between the optical sensor head 35 and the surface of the wafer W is shortened. Specifically, the optical path from the light projecting optical fiber 32 to the measurement point is shortened (see FIG. 3). Furthermore, the optical path from the measurement point to the light receiving optical fiber 33 is also shortened. As a result, the amount of light received by the light receiving optical fiber 33, i.e., the amount of received light, also varies in accordance with the variation in the thickness of the polishing pad 1.

[0078] Therefore, in this embodiment, the control device 50 determines the thickness of the polishing pad 1 from the amount of received light based on the relationship between the thickness of the polishing pad 1 and the amount of received light. Furthermore, the control device 50 determines the amount of movement of the measurement point from the thickness of the polishing pad 1 based on the first correlation data described in the first embodiment, and corrects the measurement coordinates associated with the film thickness measurement value.

[0079] In this embodiment, the control device 50 measures (determines) the amount of light received by the light-receiving optical fiber (light-receiving unit) 50, i.e., the amount of received light. For example, the control device 50 can also measure the amount of received light based on the spectrum obtained from the spectroscope 37.

[0080] 8 is a diagram showing second correlation data in this embodiment. The second correlation data indicates the relationship between the thickness of the polishing pad 1 and the amount of received light. For example, the second correlation data is stored in the storage device 50a of the control device 50. The second correlation data is obtained in advance by experiment.

[0081] The arithmetic unit 50b of the control device 50 executes calculations according to instructions included in the program, and determines the thickness of the polishing pad 1 from the measured value of the amount of received light based on the second correlation data. The process thereafter is the same as in the first embodiment. That is, the arithmetic unit 50b of the control device 50 determines the amount of movement of the measurement point from the thickness of the polishing pad 1 based on the first correlation data, and corrects the measurement coordinates based on the amount of movement of the measurement point. As shown in FIG. 8, the relationship between the thickness of the polishing pad 1 and the amount of received light is a normal distribution.

[0082] As shown in FIG. 8, the distribution of the amount of received light corresponding to the thickness of the polishing pad 1 may show a gradient. In this case, the thickness of the polishing pad 1 may not be uniquely determined for a specific amount of received light. For example, points P1 and P2 in FIG. 8 show the same amount of received light R1, but the corresponding thicknesses of the polishing pad 1 are T1 and T2, respectively, which are different thicknesses. Therefore, the control device 12 compares the amount of received light currently measured with the amount of received light previously measured, and determines the thickness of the polishing pad 1 based on the magnitude relationship between them. In this case, the storage device 12a of the control device 12 stores the amount of received light previously measured. Since the amount of received light at point A1 is lower than the amount of received light previously measured, the thickness of the polishing pad 1 is determined to be T1. Since the amount of received light at point A2 is higher than the amount of received light previously measured, the thickness of the polishing pad 1 is determined to be T2.

[0083] FIG. 9 is a flowchart showing the operation of the polishing apparatus in this embodiment. In step S201, the control device 50 measures the amount of light received by the light receiving optical fiber 33. Next, in step S202, the control device 50 determines the thickness of the polishing pad 1 corresponding to the measured value of the amount of light received from the second correlation data. Next, in step S203, the control device 50 determines the movement amount of the measurement point corresponding to the determined thickness of the polishing pad 1 from the first correlation data. Next, in step S204, the optical film thickness measurement device 30 performs film thickness measurement, and the measurement coordinates are associated with the film thickness measurement value. Next, in step S205, the control device 50 corrects the measurement coordinates associated with the film thickness measurement value by the movement amount of the measurement point determined in step S203.

[0084] In FIG. 9, steps S201 to S203 are performed before step S204, but these steps may be performed simultaneously with step S204. Steps S201 to S203 may be performed after step S204. Steps S201 and S204 may be performed when the optical sensor head 35 is positioned below the wafer W. In other words, if the upper part of the optical sensor head 35 (the light projecting optical fiber 32 and the light receiving optical fiber 33) is covered by the wafer W, the measurement of the amount of received light can be performed. For example, the amount of received light may be measured when the optical sensor head 35 moves below the wafer W during polishing of the wafer W. Also, when polishing of the wafer W is stopped, the optical sensor head 35 may be disposed below the wafer W to measure the amount of received light.

[0085] According to this embodiment, the thickness of the polishing pad 1 can be determined based on the second correlation data by measuring the amount of received light, even if the polishing apparatus does not use a configuration for measuring the thickness of the polishing pad 1. Furthermore, the movement amount of the measurement point can be determined from the thickness of the polishing pad 1 using the first correlation data. As a result, it is also possible to make the measurement coordinates associated with the film thickness measurement value indicate an accurate position.

[0086] Third embodiment In the second embodiment described above, the thickness of the polishing pad 1 is determined from the measured value of the amount of received light based on the second correlation data, and further, the movement amount of the measurement point is determined from the thickness of the polishing pad 1 based on the first correlation data. Based on such a relationship between the first correlation data and the second correlation data, a relationship also exists between the amount of received light and the movement amount of the measurement point. Therefore, in this embodiment, the movement amount of the measurement point is determined based on the amount of received light. The configuration and operation of this embodiment that are not particularly described are similar to those of the first and second embodiments described with reference to FIGS. 1 to 9, so that redundant description will be omitted. This embodiment can be implemented in either the polishing apparatus shown in FIG. 1 or the polishing apparatus shown in FIG. 7.

[0087] In this embodiment, third correlation data is used, which indicates the relationship between the amount of light received in the light receiving optical fiber 33 and the amount of movement of the measurement point. For example, the third correlation data is stored in the storage device 50a of the control device 50. The third correlation data is obtained in advance by an experiment. The calculation device 50b of the control device 50 executes calculations according to instructions included in a program, and determines the amount of movement of the measurement point from the measured value of the amount of light received based on the third correlation data. The process thereafter is the same as in the first and second embodiments. That is, the calculation device 50b of the control device 50 corrects the measurement coordinates based on the determined amount of movement of the measurement point.

[0088] 10 is a flowchart showing the operation of the polishing apparatus in this embodiment. In step S301, the control device 50 measures the amount of light received in the light-receiving optical fiber 33. Next, in step S302, the control device 50 determines the amount of movement of the measurement value corresponding to the measured amount of light received from the third correlation data. Next, in step S303, the optical film thickness measurement device 30 performs film thickness measurement, and the measurement coordinates are associated with the film thickness measurement value. Next, in step S304, the control device 50 corrects the measurement coordinates associated with the film thickness measurement value by the amount of movement of the measurement point determined in step S303.

[0089] 10, steps S301 and S302 are executed before step S303, but these steps may be executed simultaneously with step S303. Steps S301 and S302 may be executed after step S303.

[0090] According to this embodiment, the movement amount of the measurement point can be directly determined based on the measured value of the amount of received light and the third correlation data, even if the polishing apparatus does not use a configuration for measuring the thickness of the polishing pad 1. As a result, it is possible to make the measurement coordinates associated with the film thickness measurement value indicate an accurate position.

[0091] In the above embodiments, the thickness of the polishing pad 1 is reduced, but the thickness of the polishing pad 1 may temporarily increase. For example, when the polishing pad 1 swells with the polishing liquid, the thickness temporarily increases. However, even when the thickness of the polishing pad 1 increases, the above-mentioned correlations, i.e., the relationships defined in the first correlation data, the second correlation data, and the third correlation data, hold true. Therefore, each embodiment can be applied to the case where the thickness of the polishing pad 1 increases.

[0092] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments are naturally possible for a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0093] 1 polishing pad 1a Polished surface 3 Polishing table 10 Polishing Head 20 Dressing Unit 21 Dresser 29 First pad thickness measuring device 30 Optical film thickness measuring device 32 Light projection unit (optical fiber for light projection) 33 Light receiving unit (optical fiber for receiving light) 35 Optical sensor head 50 Control device 50a storage device 50b Arithmetic unit 60 Second pad thickness measuring device

Claims

1. a polishing table that rotates while supporting a polishing pad; a polishing head that presses the substrate against the polishing surface of the polishing pad; a pad thickness measuring device for measuring the thickness of the polishing pad; an optical film thickness measurement device that irradiates light obliquely onto a plurality of measurement points on the substrate, receives light reflected from the substrate, and determines film thickness measurements at the measurement points based on the reflected light; a control device that associates the film thickness measurement value with measurement coordinates that indicate the position of the measurement point, The control device performs calculations based on correlation data showing the relationship between the thickness of the polishing pad and the movement amount of the measurement coordinate, thereby determining the movement amount of the measurement coordinate corresponding to the measured thickness of the polishing pad, and the polishing apparatus is equipped with an arithmetic unit that corrects the measurement coordinate corresponding to the film thickness measurement value based on the determined movement amount of the measurement coordinate.

2. 2. The polishing apparatus according to claim 1, wherein the pad thickness measuring device measures the thickness of the polishing pad by contacting the polishing surface of the polishing pad.

3. 2. The polishing apparatus according to claim 1, wherein the pad thickness measuring device is disposed inside the polishing table and measures the thickness of the polishing pad based on the height of the surface of the substrate that contacts the polishing surface.

4. the optical film thickness measurement device includes an optical sensor head that projects and receives light between the optical sensor head and the substrate; 4. The polishing apparatus of claim 3, wherein the pad thickness measuring device measures the thickness of the polishing pad based on the height of the surface of the substrate when the pad thickness measuring device is covered together with the optical sensor head by the substrate being pressed against the polishing pad.

5. the optical film thickness measuring device includes a light projecting optical fiber that projects light obliquely onto the substrate, and a light receiving optical fiber that receives light that is obliquely reflected by the substrate; 5. The polishing apparatus according to claim 1, wherein the diameter of the light-projecting optical fiber and the diameter of the light-receiving optical fiber are different.

6. a polishing table that rotates while supporting a polishing pad; a polishing head that presses the substrate against the polishing surface of the polishing pad; an optical film thickness measurement device that irradiates light obliquely onto a plurality of measurement points on the substrate, receives light reflected from the substrate, and determines film thickness measurements at the measurement points based on the reflected light, as well as determining an amount of received light; a control device that associates the film thickness measurement value with measurement coordinates that indicate the position of the measurement point, The control device performs calculations based on first correlation data indicating the relationship between the amount of received light and the thickness of the polishing pad, and second correlation data indicating the relationship between the thickness of the polishing pad and the amount of movement of the measurement coordinate, thereby determining the thickness of the polishing pad corresponding to the amount of received light, determining the amount of movement of the measurement coordinate corresponding to the determined measurement value of the thickness of the polishing pad, and correcting the measurement coordinate corresponding to the film thickness measurement value based on the determined amount of movement of the measurement coordinate.

7. a polishing table that rotates while supporting a polishing pad; a polishing head that presses the substrate against the polishing surface of the polishing pad; an optical film thickness measurement device that irradiates light obliquely onto a plurality of measurement points on the substrate, receives light reflected from the substrate, and determines film thickness measurements at the measurement points based on the reflected light, as well as determining an amount of received light; a control device that associates the film thickness measurement value with measurement coordinates that indicate the position of the measurement point, The control device is equipped with a calculation device that determines the amount of movement of the measurement coordinate corresponding to the amount of received light by performing calculations based on correlation data that indicates the relationship between the amount of received light and the amount of movement of the measurement coordinate, and corrects the measurement coordinate associated with the film thickness measurement value based on the determined amount of movement of the measurement coordinate.

Images