Grinding 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 Art

[0002] A semiconductor device manufacturing process includes a step of polishing a wafer to planarize the surface of the wafer. As one means for polishing a wafer, a polishing apparatus that performs chemical mechanical polishing (CMP) is known. The polishing apparatus presses the wafer against the polishing surface of a polishing pad supported on a polishing table while supplying polishing liquid to the polishing surface, and relatively moves the wafer and the polishing table. Through the above steps, the surface of the wafer is polished.

[0003] The polishing performance of a polishing pad decreases each time a wafer is polished. Accordingly, the polishing apparatus performs dressing to recover the polishing performance of the polishing pad. In dressing, the polishing surface of the polishing pad is scraped with a dresser having hard abrasive grains such as diamond particles fixed thereto. Through the above process, the polishing surface of the polishing pad is regenerated (in other words, the polishing performance of the polishing pad is recovered).

[0004] Generally, a polishing apparatus includes a film thickness measuring device for measuring the film thickness on the surface of a wafer during polishing. The polishing apparatus ends polishing when the measured film thickness reaches a predetermined target value (in other words, a polishing end point). One 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 causes light to enter a measurement point on the surface of the wafer and receives reflected light from the surface of the wafer. The measured film thickness value is determined by analysis based on this reflected light. When the optical sensor head 35 is scanned across the surface of the wafer, film thickness measurement values are obtained at a plurality of measurement points on the surface of the wafer. These film thickness measurement values are associated with position coordinates (measurement coordinates) indicating the measurement position on the surface of the wafer. Prior Art Documents Patent Documents

[0005] [Patent Document 1] Patent No. 5167010 [Overview of the project] [Problems that the invention aims to solve]

[0006] The polishing pad wears down through polishing or dressing, gradually reducing its thickness. As the thickness of the polishing pad decreases, the surface of the wafer pressed against the pad moves closer to the sensor head. As a result, the position of the measurement point by the sensor head may shift before and after the change in the thickness of the polishing pad. Consequently, the position coordinates associated with the film thickness measurement may show an incorrectly shifted position.

[0007] Therefore, the present invention aims to provide a polishing apparatus that can improve the accuracy of position coordinates associated with film thickness measurement values. [Means for solving the problem]

[0008] In one embodiment, a polishing apparatus is provided comprising: 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 onto multiple measurement points on a substrate, receives reflected light from the substrate, and determines the film thickness measurement value at the measurement point based on the reflected light; and a control device that associates measurement coordinates indicating the position of the measurement point with the film thickness measurement value. The control device includes a calculation device that performs calculations based on correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement coordinate to determine the amount of movement of the measurement coordinate corresponding to the measured thickness of the polishing pad, and corrects the measurement coordinate associated with the film thickness measurement value based on the determined amount of movement of the measurement coordinate.

[0009] In one aspect, , Pa The 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, , PaThe pad thickness measuring device is positioned inside the polishing table and is configured to measure the thickness of the polishing pad based on the height of the surface of the substrate that is in contact with the polishing surface. In one embodiment, the optical film thickness measuring device includes an optical sensor head that emits and receives light between itself and a substrate. , Pa The polishing pad thickness measuring device is configured to measure the thickness of the polishing pad based on the surface height of the substrate when the substrate is pressed against the polishing pad and covered together with the optical sensor head. In one embodiment, the optical film thickness measuring device comprises a light-emitting optical fiber that irradiates light obliquely onto a substrate and a light-receiving optical fiber that receives the light obliquely reflected by the substrate, wherein the diameter of the light-emitting optical fiber and the diameter of the light-receiving optical fiber are of different sizes.

[0010] In one embodiment, a polishing apparatus is provided comprising: 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 measuring device that irradiates light obliquely onto multiple measurement points on the substrate, receives reflected light from the substrate, determines the film thickness measurement value at the measurement points based on the reflected light, and also determines the amount of light received; and a control device that associates measurement coordinates indicating the position of the measurement points with the film thickness measurement value. The control device includes a calculation device that performs calculations based on first correlation data showing the relationship between the amount of light received and the thickness of the polishing pad, and second correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement coordinates to determine the thickness of the polishing pad corresponding to the amount of light received, determines the amount of movement of the measurement coordinates corresponding to the determined polishing pad thickness measurement value, and corrects the measurement coordinates associated with the film thickness measurement value based on the determined amount of movement of the measurement coordinates.

[0011] In one embodiment, a polishing apparatus is provided comprising: 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 measuring device that irradiates light obliquely onto multiple measurement points on the substrate, receives reflected light from the substrate, determines the film thickness measurement value at the measurement points based on the reflected light, and also determines the amount of light received; and a control device that associates measurement coordinates indicating the position of the measurement points with the film thickness measurement value. The control device includes a calculation device that performs calculations based on correlation data showing the relationship between the amount of light received and the amount of movement of the measurement coordinates to determine the amount of movement of the measurement coordinates corresponding to the amount of light received, and corrects the measurement coordinates associated with the film thickness measurement value based on the determined amount of movement of the measurement coordinates. [Effects of the Invention]

[0012] The control device is configured to correct the position coordinates corresponding to the measured film thickness of the substrate by determining the amount of movement of the measurement point using a correlation based on the thickness of the polishing pad. Therefore, the polishing device can improve the accuracy of the position coordinates associated with the measured film thickness. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram showing a polishing apparatus according to the first embodiment. [Figure 2] This is a top view showing the relative positions of the wafer and polishing table during polishing. [Figure 3] This is an enlarged view showing the path of light from the light-emitting optical fiber (light-emitting section) to the light-receiving optical fiber (light-receiving section). [Figure 4] This shows an example of multiple measurement points on the surface of wafer W. [Figure 5] This figure shows an example of film thickness distribution. [Figure 6] This is a flowchart showing the operation of the polishing apparatus according to the first embodiment. [Figure 7] This figure shows a modified example of the polishing apparatus according to the first embodiment. [Figure 8] This figure shows the relationship between the thickness of the polishing pad and the amount of light received in the second embodiment. [Figure 9] It is a flow chart showing the operation of the polishing apparatus according to the second embodiment. [Figure 10] It is a flow chart showing the operation of the polishing apparatus according to the third embodiment. Mode for Carrying Out the Invention

[0014] (First Embodiment) Figure 1 is a diagram showing an embodiment of a polishing apparatus. The polishing apparatus shown in Figure 1 is an apparatus that chemically mechanically polishes workpieces such as wafers, substrates, and panels. An example of polishing a wafer will be described below. The polishing apparatus includes a polishing pad 1, a polishing table 3 that supports the polishing pad 1, a polishing liquid supply nozzle 40 that supplies a polishing liquid (for example, slurry containing abrasive grains) onto the polishing pad 1, a polishing head 10 that holds a wafer W and presses it against the polishing pad 1, a dressing unit 20 that dresses (conditions) the polishing surface 1a of the polishing pad 1, an optical film thickness measurement apparatus 30 for measuring the film thickness on the surface of the wafer W, and a control device 50 that controls 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 communicate with each other. As will be described later, the through hole 1b allows light for film thickness measurement to pass through.

[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 around 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 Figure 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 around 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 Figure 1.

[0018] The lower surface of the polishing head 10 is configured to hold the wafer W. A vacuum source (not shown) for vacuum-suctioning the wafer W is connected to the lower surface of the polishing head 10. The wafer W is held by suction to the lower surface of the polishing head 10 by the vacuum source. In other words, the lower surface of the polishing head 10 constitutes the wafer holding surface for holding the wafer W.

[0019] Furthermore, an airbag (not shown) is provided on the underside of the polishing head 10 to press the wafer W toward 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 uses the airbag to press the wafer W toward the polishing surface 1a of the polishing pad 1.

[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 raise 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 together with the polishing head shaft 12. The lifting cylinder lowers the polishing head 10, which holds 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 toward 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 that rotatably supports the dresser shaft 23, an air cylinder 26 for pressing the dresser 21 against the polishing pad 1, a dresser arm 27 that rotatably supports the dresser shaft 23, and a support shaft 28 that supports the dresser arm 27. The lower surface of the dresser 21 constitutes a dressing surface on which abrasive grains such as diamond particles are fixed. As will be 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), which is installed inside 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 together with the dresser shaft 23. For example, the dresser 21 rotates in the direction indicated by the arrow in Figure 1.

[0023] The dresser 21 is connected to the support block 25 via the dresser shaft 23. The support block 25 is connected to the 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 together with the dresser shaft 23 and the support block 25. The air cylinder 26 lowers the dresser 21 toward the polishing pad 1, 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), which is configured to rotate the support shaft 28. The support shaft 28 is rotated around its axis by the motor. The dresser 21, dresser shaft 23, and dresser arm 27 swing together as a unit around the support shaft 28 due to the rotation of the support shaft 28.

[0025] The control unit 50 consists of at least one computer. The control unit 50 includes a storage device 50a in which a program is stored, and an arithmetic unit 50b that performs calculations according to the instructions contained in the program. The storage device 50a includes a main memory such as RAM and an auxiliary storage device such as a hard disk drive (HDD) or solid-state drive (SSD). Examples of the arithmetic unit 50b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the control unit 50 is not limited to these examples.

[0026] The wafer W is polished as follows: The polishing head 10 holds the wafer W with its surface (the surface to be polished) facing the polishing pad 1. While the polishing table 3 is rotated by the table motor 5, 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 rotated by the polishing head motor and lowered by the polishing head lifting mechanism. 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 toward 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] 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 to the polishing surface 1a of the polishing pad 1 from a pure water supply nozzle (not shown). In this state, the dresser 21 is rotated by the dresser motor and lowered by the air cylinder 26. As a result, the dressing surface of the dresser 21 comes into contact with the polishing surface 1a of the polishing pad 1. The dressing surface of the dresser 21 presses against the polishing surface 1a of the polishing pad 1 by the air cylinder 26. Furthermore, the dresser 21 is oscillated and moves in parallel on the polishing surface 1a of the polishing pad 1. In this way, the polishing pad 1 is scraped 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 dressing. Dressing of the polishing surface 1a of the polishing pad 1 is performed during or after polishing the wafer W.

[0028] The optical film thickness measuring device 30 comprises a light source 31, an optical sensor head 35 positioned inside the polishing table 3, and a spectrometer 37. The light source 31, optical sensor head 35, and spectrometer 37 are mounted on the polishing table 3 and rotate together with the polishing table 3 and polishing pad 1. The optical sensor head 35 is optically connected to the light source 31 and the spectrometer 37. The light source 31 and the spectrometer 37 are connected to a control device 50.

[0029] The optical sensor head 35 comprises a light-emitting unit 32 and a light-receiving unit 33. For example, the light-emitting unit 32 and the light-receiving unit 33 are each composed of optical fiber cables. The light-emitting unit 32 may be called the light-emitting optical fiber 32, and the light-receiving unit 33 may be called the light-receiving optical fiber 33. One end (tip) of the light-emitting unit 32 and one end (tip) of the light-receiving unit 33 are directed upward and face the wafer W to be polished as described later. One end of the light-emitting unit 32 and one end of the light-receiving unit 33 are inclined to move towards each other. The other end of the light-emitting unit 32 is optically connected to the light source 31, and the other end of the light-receiving unit 34 is optically connected to the spectrometer 37.

[0030] The light source 31 can be a light-emitting diode (LED), a halogen lamp, a xenon lamp, or the like. The optical sensor head 35 directs light from the light source 31 onto the surface of the wafer W and receives the light reflected from the surface of the wafer W. Specifically, the light-emitting unit 32 guides light from the light source 31 and directs it onto the surface of the wafer W, and the light-receiving unit 33 receives the reflected light from the surface of the wafer W. The spectrometer 37 decomposes the reflected light received by the light-receiving unit 33 according to wavelength and generates a spectrum by 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 endpoint has been reached when the film thickness measurement value reaches a predetermined target value.

[0031] The optical sensor head 35 is positioned inside the hole 7 of the polishing table 3. The optical sensor head 35 only needs to be positioned below the polishing surface 1a of the polishing pad 1. In other words, one end of the light-emitting unit 32 and one end of the light-receiving unit 33 only need to be positioned below the polishing surface 1a of the polishing pad 1. As shown in Figure 1, one end of the light-emitting unit 32 and one end of the light-receiving unit 33 are positioned below the upper surface of the polishing table 3. One end of the light-emitting unit 32 and one end of the light-receiving unit 33 may also be positioned inside the through hole 1b, as long as they are below the polishing surface 1a of the polishing pad 1.

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

[0033] The light-transmitting medium may be air instead of liquid. Alternatively, a transparent window (not shown) may be provided instead of the light-transmitting liquid. The window may be located inside the through-hole 1b or inside the hole 7, provided it is positioned below the polishing surface 1a of the polishing pad 1 and above the optical sensor head 35 (the tip of the light-emitting section 32 and the light-receiving section 33). In this case, the window is provided to block at least one of the through-hole 1b and the hole 7.

[0034] Figure 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 over) the wafer W, tracing the trajectory shown by the dotted line in Figure 2, each time the polishing table 3 completes one rotation. The optical sensor head 35 is positioned at a predetermined distance from the center of the polishing table 3 in the radial direction. The center of the wafer W is positioned at a predetermined distance from the center of the polishing table 3 in the radial direction. In Figure 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 Figure 2, the optical sensor head 35 crosses the center of the wafer W as the polishing table 3 rotates.

[0035] Note that Figure 2 shows an example arrangement where 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 the bottom of the wafer W.

[0036] As the optical sensor head 35 moves below the wafer W, it intermittently irradiates the surface of the wafer W with light at predetermined time intervals. Specifically, the control device 50 controls the light source 31, causing it to emit light intermittently at predetermined time intervals. The light from the light source 31 is intermittently irradiated onto the surface of the wafer W via the light-emitting unit 32 at predetermined time intervals. As a result, light is irradiated onto multiple locations on the surface of the wafer W, and the film thickness at each location is measured.

[0037] The optical sensor head 35 may maintain light irradiation on the surface of the wafer W while moving below the wafer W to measure the film thickness. 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 emission while the optical sensor head 35 moves below the wafer W. The light from the light source 31 continues to irradiate the surface of the wafer W via the light projection unit 32. The spectrometer 12 generates spectra at predetermined time intervals. As a result, the film thickness at each location is measured by analyzing the spectra obtained at predetermined time intervals.

[0038] Hereinafter, the locations on the surface of the wafer W that are irradiated with light will be referred to as "measurement points." The time intervals at which film thickness measurements are performed will be referred to as "measurement intervals." In particular, when the optical sensor head 35 irradiates light intermittently, the time intervals between light irradiations will be referred to as the measurement intervals, and when the optical sensor head 35 irradiates light continuously, the predetermined time intervals at which the spectrometer 37 generates a spectrum will be referred to as the measurement intervals.

[0039] The control device 50 associates the measured film thickness at a measurement point with the measurement coordinates indicating the position of that measurement point. The measurement coordinates are coordinates (position coordinates) indicating the position on the surface of the wafer W. For example, the measurement coordinates are shown as the radial position on the wafer W. Each time the optical sensor head 35 passes over the wafer W, the control device 50 associates the measured film thickness at each measurement point with the measurement coordinates. In this way, the film thickness distribution is generated based on the measured film thickness and measurement coordinates at multiple measurement points. For example, the film thickness distribution is generated by the control device 50.

[0040] The film thickness distribution is shown by distributing the film thickness measurements for each measurement coordinate. The film thickness measurement at each measurement coordinate may be expressed as the average value of the film thickness measurements at that measurement coordinate. For example, the measurement coordinate can be expressed as a position on the diameter of the wafer W. In this case, the film thickness distribution can be expressed as the film thickness distribution on the diameter of the wafer W. For example, the measurement coordinate can be expressed as a position on the radius of the wafer W. In this case, the film thickness distribution can be expressed as the 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 from the table motor 5 regarding the rotation of the polishing table 3. 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 predetermined range of rotation angles. Based on this determination, the control device 50 causes the optical film thickness measuring device 30 to perform film thickness measurements at predetermined measurement intervals. Furthermore, based on this 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 a predetermined time based on the rotation angle. Furthermore, based on the determined position of the optical sensor head 35 and the measurement interval, the control device 50 determines the position of the measurement point, i.e., the measurement coordinates. In this way, the control device 50 associates the measurement coordinates with the film thickness measurement values ​​at predetermined measurement points.

[0042] The range of a predetermined rotation angle for determining whether the optical sensor head 35 is passing below 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 methods other than those described above.

[0043] Figure 3 is an enlarged view showing the path of light from the light-emitting optical fiber (light-emitting section) 32 to the light-receiving optical fiber (light-receiving section) 33. As shown in Figure 3, the tip of the light-emitting 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 angle of incidence refers to the angle between the normal of the wafer W and the incident light at the point where the light is irradiated, i.e., the measurement point, and the angle of reflection refers to the angle between the normal of the wafer W and the reflected light at the measurement point.

[0044] In this case, wafer W may have a laminated structure in which films and wiring structures made of various materials are stacked from the inside to the surface of the wafer W. When light for film thickness measurement is shone onto such a wafer W from a perpendicular direction, the light may pass through the film of the top layer of wafer W (i.e., the outermost layer of wafer W). As a result, the incident light is reflected by the inner layers beyond the top layer. In this case, the acquired spectrum includes not only information about the top layer of wafer W, but also information about the inner layers of wafer W corresponding to the layers through which the light passed. Consequently, when light for film thickness measurement is shone onto the surface of wafer W from a perpendicular direction, it can be difficult to obtain accurate film thickness measurements for the top layer of wafer W.

[0045] To obtain more accurate film thickness measurements for the uppermost layer of wafer W, the light-emitting optical fiber 32 may be positioned at an angle as described above.

[0046] The tip of the light-receiving optical fiber 33 is positioned at an angle that allows it to receive 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 light at the surface of the wafer W. That is, it is preferable that the tip of the light-receiving optical fiber 33 is positioned at an angle such that reflected light enters the light-receiving optical fiber 33 substantially perpendicular to its tip. In this case, as shown in Figure 3, the tip of the light-emitting 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 gradually decreases as it is worn down by polishing the wafer W and dressing the polishing surface 1a. In other words, the thickness of the polishing pad 1 gradually decreases. The thinner the polishing pad 1 becomes, the closer the surface of the wafer W pressed against the polishing pad 1 gets to the light-emitting optical fiber 32 and the light-receiving optical fiber 33 (i.e., the optical sensor head 35). As described above, the light-emitting optical fiber 32 emits light obliquely onto the wafer W. Therefore, as the path of light between the light-emitting optical fiber 32 and the measurement point shortens, the position of the measurement point shifts in the in-plane direction of the wafer W, as shown in Figure 3. That is, the position of the measurement point is different before and after the thickness of the polishing pad 1 decreases. As a result, the path of the reflected light changes due to the shift in the position of the measurement point, and there is a risk that the light-receiving optical fiber 33 will not be able to receive the reflected light.

[0048] Therefore, in order to enable the light-receiving optical fiber 33 to receive reflected light even if the position of the measurement point shifts, the tip of the light-emitting optical fiber 32 has a diameter large enough to tolerate the shift in the position of the measurement point. For example, as shown in Figure 3, the diameter of the light-emitting optical fiber 32 is larger than the diameter of the light-receiving optical fiber 33. As a result, even if the position of the measurement point shifts due to a decrease in the thickness of the polishing pad 1, the light-receiving optical fiber 33 can still receive reflected light.

[0049] Although not shown in the diagram, the tip of the light-receiving optical fiber 33 may have a diameter large enough to tolerate a shift in the position of the measurement point. In this case, the diameter of the light-receiving optical fiber 33 is larger than the diameter of the light-emitting optical fiber 32. Even in this case, the light-receiving optical fiber 33 can receive reflected light even if the position of the measurement point shifts.

[0050] Figure 4 shows an example of multiple measurement points on the surface of wafer W. Figure 4 shows multiple measurement points before the thickness of polishing pad 1 decreases (before wear of polishing pad 1) and multiple measurement points after the thickness of polishing pad 1 decreases (after wear of polishing pad 1). As shown in Figure 4, when the thickness of polishing pad 1 decreases, a positional shift occurs at each measurement point. Therefore, even if film thickness measurement is performed under the same measurement conditions before and after the thickness of polishing pad 1 decreases, different locations on the surface of wafer W will be measured. If the positional shift of the measurement points is not reflected in the measurement coordinates, the measurement coordinates associated with the film thickness measurement will indicate a different position from the actual measurement coordinates.

[0051] Figure 5 shows an example of film thickness distribution. As an example, Figure 5 shows the film thickness distribution along the diameter of wafer W. The film thickness distribution shown by the solid line is the film thickness distribution generated based on multiple measurement points before the thickness of polishing pad 1 decreased (before wear of polishing pad 1) as shown in Figure 4. The film thickness distribution shown by the dashed line is the film thickness distribution generated based on multiple measurement points after the thickness of polishing pad 1 decreased (after wear of polishing pad 1) as shown in Figure 4. As described above, the film thickness distribution after the thickness of polishing pad 1 decreases shows measurement coordinates corresponding to film thickness measurements at positions different from the actual positions. As a result, the film thickness distribution as a whole is shifted, as shown in Figure 5.

[0052] Therefore, in this embodiment, the measurement coordinates are corrected based on first correlation data showing the relationship between the thickness of the polishing pad 1 and the amount of displacement of the measurement point. Here, the amount of displacement of the measurement point refers to the distance the measurement point moves from its initial position in the in-plane direction of the wafer W. In other words, the amount of displacement of the measurement point indicates the degree of the positional displacement of the measurement point as 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 determined in advance by experiment.

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

[0054] Furthermore, if the thickness of the polishing pad 1 changes, the height of the polishing surface 1a also changes. 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. In other words, the first correlation data may be shown as 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 is expressed as the polishing surface 1a height relative to a reference value. surface This shows the amount of movement of the measurement point when the height of 1a changes, and each value indicating the height of the polished surface 1a is associated with the amount of movement of the measurement point.

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

[0056] The explanation will again refer to Figure 1. The polishing apparatus can measure the thickness of the polishing pad 1 using the dressing unit 20. The dressing unit 20 is equipped 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 the 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 vertical position of the dresser arm 27 is fixed. While the contact of the first pad thickness measuring device 29 remains in contact with the dresser arm 27, the first pad thickness measuring device 29 moves up and down together with the dresser shaft 23 and the dresser. 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 can measure the thickness of the polishing pad 1 by measuring the height of the polishing surface 1a with the lower surface of the polishing pad 1 as the reference surface. 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 while the polishing pad 1 is being dressed. It is also possible to stop the rotation of the polishing table 3 and the rotation of the dresser 21 and measure the thickness of the polishing pad 1 while the 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 positioned to measure the displacement of the support block 25. In this case as well, 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 by the relationship between the height of the polishing surface 1a measured in this way 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 the output signal from the first pad thickness measuring device 29. That is, the control device 50 can receive the measured thickness of the polishing pad 1 measured by the first pad thickness measuring device 29. Also, as described above, if the height of the polishing surface 1a is measured by the first pad thickness measuring device 29, the control device 50 can receive the measured height of the polishing surface 1a.

[0061] Alternatively, 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 via the polishing head 10.

[0062] Figure 6 is a flowchart illustrating the operation of the polishing apparatus shown in Figure 1. In step S101, the thickness of the polishing pad 1 is measured by the pad height measuring device of the dressing unit 20. Next, in step S102, the control device 50 determines the amount of movement 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. Next, in step S104, the control device 50 corrects the measurement coordinates associated with the film thickness measurement by the amount of movement of the measurement point determined in step S102. As a result, the measurement coordinates associated with the film thickness measurement show a more accurate position. Furthermore, it is possible to suppress the overall shift in the film thickness distribution as shown in Figure 5.

[0063] Note that in Figure 6, steps S101 and step SAlthough step 102 is executed before step S103, these steps may be performed concurrently with step S103. S Step 102 may be performed after step S103.

[0064] The thickness of the polishing pad 1 and the height of the polishing surface 1a can also be measured using the polishing apparatus shown in Figure 7. Figure 7 shows a modified example of the polishing apparatus of this embodiment. Unless otherwise specified, the polishing apparatus in Figure 7 has the same configuration as the polishing apparatus in Figure 1, so redundant explanations will be omitted. The following explanation will refer to Figure 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 will be described later, the through hole 1c allows light to pass through for measuring the thickness of the polishing pad 1. The second pad thickness measuring device 60 is positioned inside the polishing table 3. Specifically, the second pad thickness measuring device 60 is positioned inside the hole 71 and below the upper surface of the polishing table 3.

[0066] In Figure 7, the dressing unit 20 does not include the support block 25 and the first pad thickness measuring device 29, but it 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 emits light when the top of the polishing pad 1 is covered by the wafer W placed on the polishing pad 1, and measures the thickness of the polishing pad 1 by receiving the reflected light that returns from the wafer W. At the time of measurement, the surface of the wafer W can be considered to be 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] The second pad thickness measuring device 60, similar to the first pad thickness measuring device 29 described above, can measure the thickness of the polishing pad 1 by measuring the height of the polishing surface 1a (more precisely, the height of the surface of the wafer W) using the lower surface of the polishing pad 1 as a reference surface.

[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 by the relationship between the height of the polishing surface 1a measured in this way 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 the 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. Also, 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] Furthermore, each step described with reference to Figure 6 can also be performed in the polishing apparatus shown in Figure 7. In particular, step S101 in Figure 6 can be performed using the second pad thickness measuring device.

[0072] Here, as the optical sensor head 35 moves below the wafer W and performs 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 is temporarily closer to the surface of the wafer W. To measure the thickness of the polishing pad 1, including the effect of the pressing load near the optical sensor head 35, a second pad thickness measuring device 60 may be positioned to be covered by the wafer W at the same time as the optical sensor head 35.

[0073] According to this embodiment, even if the measurement point moves from its initial position due to fluctuations in the thickness of the polishing pad 1, the measurement coordinates associated with the film thickness measurement can accurately indicate the correct position. In other words, the accuracy of the position coordinates associated with the film thickness measurement can be improved. In particular, when light for film thickness measurement is incident obliquely on the surface of the wafer W, the measurement point shifts in the in-plane direction of the wafer W due to fluctuations in the thickness of the polishing pad 1. This embodiment measures the thickness of the polishing pad 1 and determines the amount of movement of the measurement point (the distance the measurement point has shifted) based on the relationship between the thickness of the polishing pad 1 and the amount of movement of the measurement point (first correlation data). By correcting the measurement coordinates based on the amount of movement of the measurement point determined in this way, the measurement coordinates associated with the film thickness measurement can accurately indicate the correct position even if the thickness of the polishing pad 1 fluctuates.

[0074] According to this embodiment, by irradiating the surface of the wafer W with light while the light-emitting optical fiber 32 is tilted, it is possible to suppress information about the interior of the wafer W included in the obtained spectrum and emphasize information about the uppermost layer of the wafer W.

[0075] According to this embodiment, even if the measurement point moves due to variations 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 optical fibers, the light-emitting optical fiber 32 and the light-receiving optical fiber 33, larger than the diameter of the other optical fiber, it is possible to accommodate variations in the light path due to the movement of the measurement point.

[0076] (Second Embodiment) In the first embodiment described above, the thickness of the polishing pad 1 was measured to determine the amount of movement of the measurement point. In this embodiment, the amount of movement of the measurement point is determined without measuring the thickness of the polishing pad 1. The configuration and operation of this embodiment, which will not be specifically described, are the same as those of the first embodiment described with reference to Figures 1 to 7, so redundant explanations will be omitted. This embodiment can be performed using either the polishing apparatus shown in Figure 1 or the polishing apparatus shown in Figure 7.

[0077] As described in the first embodiment, when the thickness of the polishing pad 1 decreases, the light path between the optical sensor head 35 and the surface of the wafer W becomes shorter. Specifically, the light path from the light-emitting optical fiber 32 to the measurement point becomes shorter (see Figure 3). Furthermore, the light path from the measurement point to the light-receiving optical fiber 33 also becomes shorter. As a result, the amount of light received by the light-receiving optical fiber 33, i.e., the amount of light received, also changes 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 light received, based on the relationship between the thickness of the polishing pad 1 and the amount of light received. 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 light received. For example, the control device 50 can also measure the amount of light received based on the spectrum obtained from the spectrometer 37.

[0080] Figure 8 shows the second correlation data in this embodiment. The second correlation data shows the relationship between the thickness of the polishing pad 1 and the amount of light received. For example, the second correlation data is stored in the storage device 50a of the control device 50. The second correlation data is determined in advance through experiments.

[0081] The arithmetic unit 50b of the control device 50 performs calculations according to the commands included in the program, and determines the thickness of the polishing pad 1 from the measured amount of light received 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 Figure 8, the relationship between the thickness of the polishing pad 1 and the amount of light received follows a normal distribution.

[0082] Furthermore, as shown in Figure 8, the distribution of light received corresponding to the thickness of the polishing pad 1 may show a slope. In this case, the thickness of the polishing pad 1 may not be uniquely determined for a specific amount of light received. For example, points P1 and P2 in Figure 8 show the same amount of light received R1, but the corresponding thicknesses of the polishing pad 1 are T1 and T2, respectively, which are different thicknesses. Therefore, the control device 50 The currently measured amount of light received is compared with the previously measured amount of light received, and the thickness of the polishing pad 1 is determined based on the relationship between the two amounts. In this case, the control device 50 storage 50a It remembers the amount of light received in the previous measurement. P Since the amount of light received at point 1 is lower than the amount of light received in the previous measurement, the thickness of polishing pad 1 is determined to be T1. P Since the amount of light received at point 2 is higher than the amount of light received in the previous measurement, the thickness of polishing pad 1 is determined to be T2.

[0083] Figure 9 is a flowchart illustrating 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 amount of light received from the second correlation data. Next, in step S203, the control device 50 determines the amount of movement 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 measuring device 30 performs film thickness measurement, and the measurement coordinates are associated with the film thickness measurement. Next, in step S205, the control device 50 corrects the measurement coordinates associated with the film thickness measurement by the amount of movement of the measurement point determined in step S203.

[0084] In Figure 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 also be performed after step S204. Steps S201 and S204 should 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 (light-emitting optical fiber 32 and light-receiving optical fiber 33) is covered by the wafer W, the amount of light received can be measured. For example, the amount of light received may be measured when the optical sensor head 35 is moving below the wafer W during wafer polishing. Alternatively, when wafer polishing of the wafer W is stopped, the optical sensor head 35 may be positioned below the wafer W and the amount of light received may be measured.

[0085] According to this embodiment, even without a configuration in the polishing apparatus to measure the thickness of the polishing pad 1, the thickness of the polishing pad 1 can be determined based on the second correlation data by measuring the amount of light received. Furthermore, the amount of movement of the measurement point can be determined from the thickness of the polishing pad 1 using the first correlation data. As a result, the measurement coordinates associated with the film thickness measurement can be made to 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 amount of light received based on the second correlation data, and furthermore, the amount of movement of the measurement point is determined from the thickness of the polishing pad 1 based on the first correlation data. Based on the relationship between the first and second correlation data, a relationship also holds between the amount of light received and the amount of movement of the measurement point. Therefore, in this embodiment, the amount of movement of the measurement point is determined based on the amount of light received. The configuration and operation of this embodiment, which will not be specifically described, are the same as those of the first and second embodiments described with reference to Figures 1 to 9, so redundant explanations will be omitted. Note that this embodiment can be performed using either the polishing apparatus shown in Figure 1 or the polishing apparatus shown in Figure 7.

[0087] In this embodiment, a third correlation data is used that shows 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 determined in advance by experiment. The arithmetic unit 50b of the control device 50 performs calculations according to the commands included in the program, and determines the amount of movement of the measurement point from the measured 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 arithmetic unit 50b of the control device 50 corrects the measurement coordinates based on the determined amount of movement of the measurement point.

[0088] Figure 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 by the light-receiving optical fiber 33. Next, in step S302, the control device 50 determines the amount of movement of the measured value corresponding to the measured amount of light received from the third correlation data. Next, in step S303, the optical film thickness measuring device 30 performs film thickness measurement, and the measured film thickness is associated with the measurement coordinates. Next, in step S304, the control device 50 corrects the measurement coordinates associated with the film thickness measurement by the amount of movement of the measurement point determined in step S303.

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

[0090] According to this embodiment, even without using a configuration in the polishing apparatus to measure the thickness of the polishing pad 1, the amount of movement of the measurement point can be directly determined based on the measured amount of light received and the third correlation data. As a result, the measurement coordinates associated with the film thickness measurement can be made to indicate an accurate position.

[0091] In the embodiments described above, the example was explained using a decrease in the thickness of the polishing pad 1, but the thickness of the polishing pad 1 may also temporarily increase. For example, when the polishing pad 1 swells with polishing fluid, its thickness temporarily increases. However, even when the thickness of the polishing pad 1 increases, the relationships defined in the correlations described above, namely the first correlation data, the second correlation data, and the third correlation data, still hold. Therefore, each embodiment can also be applied when the thickness of the polishing pad 1 increases.

[0092] Each of the embodiments described above is intended to enable a person with ordinary skill in the art to implement the present invention. Various modifications of the above embodiments can be made naturally by a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments as well. Therefore, the present invention is not limited to the embodiments described, but is to be interpreted in the broadest sense according to the technical idea defined by the claims. [Explanation of Symbols]

[0093] 1. Polishing pad 1a Polished surface 3 Polishing Table 10 polishing heads 20 Dressing Units 21 Dresser 29. First pad thickness measuring device 30 Optical film thickness measuring device 32. Light-emitting section (optical fiber for light emission) 33. Light-receiving section (optical fiber for light reception) 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 the 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 measuring device that irradiates light obliquely onto multiple measurement points on the substrate, receives the reflected light from the substrate, and determines the film thickness measurement value at the measurement point based on the reflected light, The system includes a control device that associates the measured film thickness with measurement coordinates indicating the position of the measurement point, Polishing apparatus comprising a control device that performs calculations based on correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad, to determine the amount of movement of the measurement point corresponding to the measured thickness of the polishing pad, and corrects the measurement coordinates associated with the measured film thickness based on the determined amount of movement of the measurement point.

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. The polishing apparatus according to claim 1, wherein the pad thickness measuring device is arranged inside the polishing table and measures the thickness of the polishing pad based on the height of the surface of the substrate that is in contact with the polishing surface.

4. The optical film thickness measuring device includes an optical sensor head that emits and receives light between itself and the substrate, The polishing apparatus according to 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 pressed against the polishing pad.

5. A polishing table that rotates while supporting the polishing pad, A polishing head that presses the substrate against the polishing surface of the polishing pad, An optical film thickness measuring device that irradiates light obliquely onto multiple measurement points on the substrate, receives reflected light from the substrate, determines the film thickness measurement value at the measurement points based on the reflected light, and also determines the amount of light received, The system includes a control device that associates the measured film thickness with measurement coordinates indicating the position of the measurement point, Polishing apparatus comprising a control device that performs calculations based on first correlation data showing the relationship between the amount of light received and the thickness of the polishing pad, and second correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement point showing the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad, thereby determining the thickness of the polishing pad corresponding to the amount of light received, determining the amount of movement of the measurement point corresponding to the determined thickness of the polishing pad, and correcting the measurement coordinates associated with the film thickness measurement value based on the determined amount of movement of the measurement point.

6. A polishing table that rotates while supporting the polishing pad, A polishing head that presses the substrate against the polishing surface of the polishing pad, An optical film thickness measuring device that irradiates light obliquely onto multiple measurement points on the substrate, receives reflected light from the substrate, determines the film thickness measurement value at the measurement points based on the reflected light, and also determines the amount of light received, The system includes a control device that associates the measured film thickness with measurement coordinates indicating the position of the measurement point, The polishing apparatus includes a control device that performs calculations based on correlation data showing the relationship between the amount of light received and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to a change in the thickness of the polishing pad, to determine the amount of movement of the measurement point corresponding to the amount of light received, and corrects the measurement coordinates associated with the film thickness measurement value based on the determined amount of movement of the measurement point.

7. The optical film thickness measuring device comprises a light-emitting optical fiber that irradiates light obliquely onto the substrate, and a light-receiving optical fiber that receives the light obliquely reflected by the substrate. The polishing apparatus according to any one of claims 1 to 6, wherein the diameter of the light-emitting optical fiber and the diameter of the light-receiving optical fiber are of different sizes.

8. Rotate the polishing table that supports the polishing pad, The polishing head presses the substrate against the polishing surface of the polishing pad, The thickness of the polishing pad is measured, Light is shone obliquely onto multiple measurement points on the substrate, the reflected light from the substrate is received, and the film thickness measurement value at the measurement point is determined based on the reflected light. The measurement coordinates indicating the position of the measurement point are associated with the aforementioned film thickness measurement. Based on correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad, the amount of movement of the measurement point corresponding to the measured thickness of the polishing pad is determined. A polishing method that corrects the measurement coordinates associated with the film thickness measurement based on the determined amount of movement of the measurement point.

9. Rotate the polishing table that supports the polishing pad, The polishing head presses the substrate against the polishing surface of the polishing pad, Light is shone obliquely onto multiple measurement points on the substrate, the reflected light from the substrate is received, the film thickness measurement value at the measurement point is determined based on the reflected light, and the amount of light received is also determined. The measurement coordinates indicating the position of the measurement point are associated with the aforementioned film thickness measurement. Based on the first correlation data showing the relationship between the amount of light received and the thickness of the polishing pad, the thickness of the polishing pad corresponding to the amount of light received is determined. Based on second correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad, the amount of movement of the measurement point corresponding to the determined thickness of the polishing pad is determined. A polishing method that corrects the measurement coordinates associated with the film thickness measurement based on the determined amount of movement of the measurement point.

10. Rotating the polishing table that supports the polishing pad, The polishing head presses the substrate against the polishing surface of the polishing pad, Light is shone obliquely onto multiple measurement points on the substrate, the reflected light from the substrate is received, the film thickness measurement value at the measurement point is determined based on the reflected light, and the amount of light received is also determined. The measurement coordinates indicating the position of the measurement point are associated with the aforementioned film thickness measurement. Based on correlation data showing the relationship between the amount of light received and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad, the amount of movement of the measurement point corresponding to the amount of light received is determined. A polishing method that corrects the measurement coordinates associated with the film thickness measurement based on the determined amount of movement of the measurement point.

11. A step of rotating a polishing table that supports a polishing pad, The steps include pressing the substrate against the polishing surface of the polishing pad using the polishing head, The steps include measuring the thickness of the polishing pad, The steps include: irradiating light obliquely onto a plurality of measurement points on the substrate, receiving the reflected light from the substrate, and determining the film thickness measurement value at the measurement point based on the reflected light; The steps include associating the measurement of the film thickness with the measurement coordinates indicating the position of the measurement point, A step of determining the amount of movement of the measurement point corresponding to the measured thickness of the polishing pad, based on correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad; A program for causing a polishing apparatus equipped with a computer to perform the step of correcting the measurement coordinates associated with the film thickness measurement based on the determined amount of movement of the measurement point.

12. A step of rotating a polishing table that supports a polishing pad, The steps include pressing the substrate against the polishing surface of the polishing pad using the polishing head, The steps include: irradiating light obliquely onto multiple measurement points on the substrate, receiving the reflected light from the substrate, determining the film thickness measurement value at the measurement points based on the reflected light, and determining the amount of light received; The steps include associating the measurement of the film thickness with the measurement coordinates indicating the position of the measurement point, A step of determining the thickness of the polishing pad corresponding to the amount of light received, based on first correlation data showing the relationship between the amount of light received and the thickness of the polishing pad, A step of determining the amount of movement of the measurement point corresponding to the determined thickness of the polishing pad, based on second correlation data showing the relationship between the thickness of the polishing pad and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad, A program for causing a polishing apparatus equipped with a computer to perform the step of correcting the measurement coordinates associated with the film thickness measurement based on the determined amount of movement of the measurement point.

13. A step of rotating a polishing table that supports a polishing pad, The steps include pressing the substrate against the polishing surface of the polishing pad using the polishing head, The steps include: irradiating light obliquely onto multiple measurement points on the substrate, receiving the reflected light from the substrate, determining the film thickness measurement value at the measurement points based on the reflected light, and determining the amount of light received; The steps include associating the measurement of the film thickness with the measurement coordinates indicating the position of the measurement point, A step of determining the amount of movement of the measurement point corresponding to the amount of light received, based on correlation data showing the relationship between the amount of light received and the amount of movement of the measurement point, which indicates the amount of positional displacement of the measurement point due to the change in the thickness of the polishing pad, A program for causing a polishing apparatus equipped with a computer to perform the step of correcting the measurement coordinates associated with the film thickness measurement based on the determined amount of movement of the measurement point.

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