Surface quality measurement system, surface quality measurement method, polishing device and polishing method

Abstract

To provide a surface quality measurement system which can accurately measure the surface quality of a polishing pad without damaging the polishing pad and reducing the throughput of the entire polishing processing.SOLUTION: A surface quality measurement system 40 comprises: an optical measurement device 41 which irradiates a polishing surface 2a of a rotating polishing pad 2 with light and measures the surface quality of the polishing pad 2 on the basis of reflection light from the polishing surface 2a; a cover member 44 which is arranged between the optical measurement device 41 and the polishing pad 2; and a transparent liquid supply line 45 which is connected to an injection port 44b provided in the cover member 44 and supplies transparent liquid onto the polishing pad 2 through the injection port 44b. The cover member 44 includes a light transmission part 44a on an optical path of light and reflection light.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a surface texture measuring system and a surface texture measuring method for measuring the surface texture of a polishing pad used to polish substrates such as wafers, as well as a polishing apparatus equipped with such a surface texture measuring system and a polishing method using the surface texture measuring method. [Background technology]

[0002] In the manufacturing process of semiconductor devices, planarization of semiconductor device surfaces is becoming increasingly important. The most important technology for this surface planarization is chemical mechanical polishing (CMP). Chemical mechanical polishing (hereinafter referred to as CMP) is a process in which a substrate such as a wafer is polished by supplying a polishing liquid containing abrasive grains such as silica (SiO2) onto the polishing surface of a polishing pad while sliding the substrate against the polishing surface.

[0003] A polishing apparatus for performing CMP includes a polishing table that supports a polishing pad having a polishing surface, and a polishing head that holds a substrate and presses it against the polishing pad. The polishing apparatus polishes a substrate as follows: A polishing liquid (typically a slurry) is supplied to the polishing surface of the polishing pad while the polishing table and polishing pad are rotated together. The polishing head presses the surface of the substrate against the polishing surface of the polishing pad while rotating the substrate. The substrate is brought into sliding contact with the polishing pad in the presence of the polishing liquid. The surface of the substrate is polished by the chemical action of the polishing liquid and the mechanical action of the abrasive grains contained in the polishing liquid and / or the polishing pad.

[0004] When polishing a substrate, abrasive grains and polishing debris adhere to the polishing surface of the polishing pad, reducing its polishing performance. Therefore, to restore the polishing surface of the polishing pad, the polishing pad is dressed (conditioned) using a dresser. The dresser has hard abrasive grains, such as diamond particles, fixed to its underside, and the polishing surface of the polishing pad is regenerated by scraping it away with the dresser.

[0005] Polishing pads gradually wear down as they are repeatedly used to polish and dress substrates, and polishing debris adheres to the surface of the polishing pad. Such changes in the surface properties of the polishing pad reduce the polishing performance of the polishing pad, resulting in a decrease in the substrate removal rate. Therefore, the surface properties of polishing pads are measured. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-174156 Summary of the Invention [Problem to be solved by the invention]

[0007] The surface texture of a polishing pad is measured by an optical measurement method in which light is irradiated onto the surface of the polishing pad and the reflected light is used. If polishing liquid or polishing debris is present on the optical path during measurement, the surface texture of the polishing pad cannot be accurately measured. Therefore, in order to remove the polishing liquid or polishing debris present on the optical path during measurement and obtain the surface texture of the polishing pad in a wet state as used in actual polishing, the surface texture is measured with a liquid film present on the surface of the polishing pad.

[0008] Patent Document 1 discloses a method for measuring the surface quality of a polishing pad based on light from the polishing pad, using a weir to form a liquid film of a certain thickness or more, without creating an unstable gas-liquid interface in the optical path. However, the method disclosed in Patent Document 1 requires the installation and removal of the weir after polishing a substrate and before polishing the next substrate. This reduces the throughput of the entire polishing process. Furthermore, contact of the weir with the polishing pad can cause impurities to adhere to the polishing pad, potentially resulting in defects during substrate polishing.

[0009] Therefore, the present invention provides a surface texture measuring system and a surface texture measuring method that can accurately measure the surface texture of a polishing pad in a short time without damaging the polishing pad, as well as a polishing apparatus equipped with such a surface texture measuring system and a polishing method that uses the surface texture measuring method. [Means for solving the problem]

[0010] In one aspect, a surface property measurement system is provided, comprising: an optical measuring device that irradiates light onto the polishing surface of a rotating polishing pad and measures the surface property of the polishing pad based on the light reflected from the polishing surface; a cover member arranged between the optical measuring device and the polishing pad; and a transparent liquid supply line connected to an injection port provided in the cover member and that supplies a transparent liquid onto the polishing pad through the injection port, wherein the cover member has a light-transmitting portion on the optical path of the light and the reflected light. In one embodiment, the injection port is located upstream of the light transmitting portion in the rotation direction of the polishing pad. In one embodiment, the injection port is located downstream of the light transmitting portion in the rotation direction of the polishing pad.

[0011] In one aspect, the surface texture measuring system further includes a supply flow rate adjustment valve capable of adjusting the flow rate of the transparent liquid supplied from the transparent liquid supply line. In one embodiment, the surface texture measuring system further includes a transparent liquid suction line connected to a suction port provided in the cover member and configured to suck the transparent liquid on the polishing pad through the suction port. In one aspect, the surface texture measuring system further includes a suction flow rate adjustment valve that adjusts the flow rate of the transparent liquid sucked by the transparent liquid suction line.

[0012] In one embodiment, the cover member has an opposing surface that is parallel to the polishing surface of the polishing pad. In one embodiment, the distance from the polishing surface of the polishing pad to the opposing surface is 5 mm or less. In one embodiment, the surface texture measuring system further includes a cover member height adjustment mechanism that adjusts the height of the cover member relative to the polishing surface. In one embodiment, the surface texture measurement system further includes an imaging device that generates an image of a monitoring area including a measurement point on the polished surface where the light is irradiated and reflected.

[0013] In one aspect, the surface texture measurement system further includes a supply flow rate control valve capable of adjusting the flow rate of the transparent liquid supplied from the transparent liquid supply line, and an operation control unit, and the operation control unit is configured to control the operation of the supply flow rate control valve based on the image of the monitoring area. In one aspect, the surface property measurement system further includes a transparent liquid suction line connected to a suction port provided in the cover member and suctioning the transparent liquid on the polishing pad through the suction port, and a suction flow rate control valve capable of adjusting the flow rate of the transparent liquid suctioned from the transparent liquid supply line, and the operation control unit is configured to control the operation of the suction flow rate control valve based on the image of the monitoring area. In one aspect, the operation control unit is configured to issue an alarm when an abnormality in the flow of the transparent liquid on the polishing pad is detected based on the image of the monitoring area. In one aspect, the surface texture measurement system further includes a first prism disposed between the optical measurement device and the cover member, the first prism passing the light irradiated from the optical measurement device and deflecting the optical path of the light; a second prism disposed between the optical measurement device and the cover member, the second prism passing the light reflected from the polishing surface and deflecting the optical path of the reflected light; and a light-shielding member disposed between the first prism and the second prism, providing light-blocking between the first prism and the second prism, wherein the cover members include a first cover member passing the light irradiated from the optical measurement device and a second cover member passing the light reflected from the polishing surface, and the light-shielding member is disposed between the first cover member and the second cover member and configured to provide light-blocking between the first cover member and the second cover member.

[0014] In one aspect, a polishing apparatus is provided, comprising the above-mentioned surface property measurement system, a polishing table that supports the polishing pad, a table motor that rotates the polishing table together with the polishing pad, and a polishing head that presses a substrate against the polishing surface of the polishing pad to polish the substrate.

[0015] In one aspect, a surface property measurement method is provided, which includes rotating a polishing table together with a polishing pad while the polishing pad is supported on the polishing table, supplying a transparent liquid onto the polishing pad through an inlet provided in a cover member having a light-transmitting portion arranged between an optical measurement device and the polishing pad, irradiating light onto the polishing surface of the polishing pad through the light-transmitting portion using the optical measurement device, receiving reflected light from the polishing surface through the light-transmitting portion, and measuring the surface property of the polishing pad based on the reflected light. In one embodiment, the injection port is located upstream of the light transmitting portion in the rotation direction of the polishing pad. In one embodiment, the injection port is located downstream of the light transmitting portion in the rotation direction of the polishing pad.

[0016] In one embodiment, the surface texture measuring method further includes adjusting a flow rate of the transparent liquid supplied onto the polishing pad. In one aspect, the surface property measuring method further includes sucking the transparent liquid from the polishing pad through an inlet provided in the cover member while supplying the transparent liquid onto the polishing pad through the inlet. In one embodiment, the surface texture measuring method further includes adjusting the flow rate of the transparent liquid sucked from above the polishing pad.

[0017] In one embodiment, the cover member has an opposing surface that is parallel to the polishing surface of the polishing pad. In one embodiment, the distance from the polishing surface of the polishing pad to the opposing surface is 5 mm or less. In one embodiment, the surface texture measuring method further includes adjusting the height of the cover member relative to the polishing surface. In one embodiment, the surface texture measuring method further includes generating, by an imaging device, an image of a monitoring area including a measurement point on the polished surface where the light is irradiated and reflected.

[0018] In one embodiment, the surface texture measuring method further includes adjusting a flow rate of the transparent liquid supplied onto the polishing pad based on the image of the monitoring area. In one aspect, the surface property measuring method further includes supplying the transparent liquid onto the polishing pad through the injection port while sucking the transparent liquid from the polishing pad through an intake port provided in the cover member, and adjusting the flow rate of the transparent liquid sucked from the polishing pad based on the image of the monitoring area. In one embodiment, the surface texture measuring method further includes issuing an alarm when an abnormality in the flow of the transparent liquid on the polishing pad is detected based on the image of the monitoring area.

[0019] In one aspect, a polishing method is provided, which includes polishing a substrate using a polishing pad, measuring the surface texture of the polishing pad using the surface texture measurement method described above, and determining whether or not it is time to replace the polishing pad based on the results of the surface texture measurement. In one aspect, a polishing method is provided, which includes supporting a new polishing pad on a polishing table, polishing a substrate for break-in treatment to break in the new polishing pad, measuring the surface property of the new polishing pad using the surface property measurement method described above, determining whether the break-in treatment is complete based on the measurement results of the surface property, and when it is determined that the break-in treatment is complete, polishing a substrate using the new polishing pad. [Effects of the Invention]

[0020] According to the present invention, the surface texture measurement system includes a cover member disposed between the optical measurement device and the polishing pad, and a transparent liquid is supplied onto the polishing pad through an inlet provided in the cover member. This allows the transparent liquid to be supplied onto the optical path during optical measurement without the cover member coming into contact with the polishing pad, thereby preventing impurities from adhering to the substrate and, as a result, preventing defects from occurring during substrate polishing. Furthermore, because no time is required for preparation for measurement, the surface texture of the polishing pad can be accurately measured in a short time.

[0021] Furthermore, according to the present invention, the transparent liquid is supplied onto the polishing pad through an inlet provided in the cover member, while the transparent liquid on the polishing pad is sucked through an inlet provided in the cover member, thereby preventing the polishing liquid from being diluted by the transparent liquid when measuring the surface texture of the polishing pad during polishing of a substrate with the polishing liquid. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a top view showing an embodiment of a polishing apparatus. [Figure 2] FIG. 2 is a side view of the polishing apparatus shown in FIG. [Figure 3] FIG. 2 is a diagram showing how an optical measuring device measures the polishing surface of a polishing pad. [Figure 4] FIG. 2 is a diagram showing a plurality of measurement points on the polishing surface of a polishing pad. [Figure 5] 10 is a graph showing the relationship between distance measured at a plurality of measurement points and measurement time. [Figure 6] Figure 6(a) is a diagram showing the optical measuring device measuring a flat portion of the polished surface where no recesses are formed, and Figure 6(b) is a diagram showing the optical measuring device measuring the bottom of a recess formed on the polished surface. [Figure 7] FIG. 7(a) is a diagram showing the optical measurement device measuring a worn polished surface, and FIG. 7(b) is a diagram showing the optical measurement device measuring a polished surface with polishing debris clogging the recesses. [Figure 8] 10 is a graph showing the relationship between the distance and the measurement time that changes over the course of use of the polishing pad. [Figure 9] FIG. 1 is a schematic diagram illustrating an embodiment of a surface texture measurement system. [Figure 10] 1 is a flowchart illustrating an embodiment of a process for measuring the surface texture of a polishing pad. [Figure 11] 10 is a flowchart illustrating another embodiment of a process for measuring the surface texture of a polishing pad. [Figure 12] FIG. 10 is a schematic diagram showing another embodiment of the surface texture measuring system. [Figure 13] FIG. 13 is a top view of the surface texture measuring system shown in FIG. 12. [Figure 14] FIG. 10 is a schematic diagram showing yet another embodiment of the surface texture measuring system. [Figure 15] FIG. 10 is a schematic diagram showing another embodiment of the optical measurement device. [Figure 16] FIG. 10 is a schematic diagram showing yet another embodiment of the optical measurement device. [Figure 17] FIG. 10 is a schematic diagram showing yet another embodiment of the optical measurement device. [Figure 18] FIG. 10 is a schematic diagram showing yet another embodiment of the surface texture measuring system. [Figure 19] FIG. 10 is a schematic diagram showing yet another embodiment of the surface texture measuring system. [Figure 20] FIG. 10 is a schematic diagram showing yet another embodiment of the surface texture measuring system. [Figure 21] FIG. 10 is a schematic diagram showing yet another embodiment of the surface texture measuring system. [Figure 22] FIG. 10 is a schematic diagram showing yet another embodiment of the surface texture measuring system. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a top view showing one embodiment of a polishing apparatus. FIG. 2 is a side view of the polishing apparatus shown in FIG. 1. The polishing apparatus 1 is an apparatus that chemically and mechanically polishes a substrate W such as a wafer. As shown in FIGS. 1 and 2, this polishing apparatus includes a polishing table 3 that supports a polishing pad 2 having a polishing surface 2a, a polishing head 1 that presses the substrate W against the polishing surface 2a, a polishing liquid supply nozzle 5 that supplies a polishing liquid (e.g., a slurry containing abrasive grains) to the polishing surface 2a, and a dresser 20 that dresses (conditions) the polishing surface 2a of the polishing pad 2.

[0024] The polishing apparatus further includes a polishing head swing shaft 14, a polishing head swing arm 16 connected to the upper end of the polishing head swing shaft 14, and a polishing head shaft 10 rotatably supported at the free end of the polishing head swing arm 16. The polishing head 1 is fixed to the lower end of the polishing head shaft 10. The polishing head 1 is configured to be able to hold a substrate W on its lower surface. The substrate W is held with the surface to be polished facing downward.

[0025] A polishing head swinging mechanism (not shown) equipped with an electric motor or the like is disposed within the polishing head swinging arm 16. The polishing head swinging mechanism is connected to the polishing head swinging shaft 14. This polishing head swinging mechanism is configured to swing the polishing head 1 and the polishing head shaft 10 around the axis of the polishing head swinging shaft 14 via the polishing head swinging arm 16. Furthermore, a polishing head rotating mechanism (not shown) equipped with an electric motor or the like is disposed within the polishing head swinging arm 16. This polishing head rotating mechanism is connected to the polishing head shaft 10 and is configured to rotate the polishing head shaft 10 and the polishing head 1 around the axis of the polishing head shaft 10.

[0026] The polishing head shaft 10 is connected to a polishing head lifting mechanism (including, for example, a ball screw mechanism) not shown. This polishing head lifting mechanism is configured to move the polishing head shaft 10 up and down relative to the polishing head swing arm 16. The up and down movement of the polishing head shaft 10 allows the polishing head 1 to move up and down relative to the polishing head swing arm 16 and the polishing table 3.

[0027] The polishing apparatus further includes a table motor 6 that rotates the polishing table 3 together with the polishing pad 2. The table motor 6 is disposed below the polishing table 3, and the polishing table 3 is connected to the table motor 6 via a table shaft 3a. The polishing table 3 and the polishing pad 2 are rotated around the axis of the table shaft 3a by the table motor 6. The polishing pad 2 is affixed to the upper surface of the polishing table 3. The exposed surface of the polishing pad 2 forms a polishing surface 2a that polishes a substrate W such as a wafer.

[0028] The dresser 20 includes a dressing disk 22 that contacts the polishing surface 2a of the polishing pad 2, a dresser shaft 24 connected to the dressing disk 22, a support block 25 that rotatably supports the upper end of the dresser shaft 24, a dresser swing arm 29 that rotatably supports the dresser shaft 24, and a dresser swing shaft 30 that supports the dresser swing arm 29. The lower surface of the dressing disk 22 forms a dressing surface on which abrasive grains such as diamond particles are fixed.

[0029] A dresser swing mechanism (not shown) equipped with an electric motor and the like is disposed within the dresser swing arm 29. The dresser swing mechanism is connected to a dresser swing shaft 30. This dresser swing mechanism is configured to swing the dressing disk 22 and the dresser shaft 24 about the axis of the dresser swing shaft 30 via the dresser swing arm 29.

[0030] The dresser shaft 24 is connected to a disk pressing mechanism (including, for example, an air cylinder) (not shown) arranged inside the dresser swing arm 29. This disk pressing mechanism is configured to press the lower surface of the dressing disk 22, which constitutes the dressing surface, against the polishing surface 2a of the polishing pad 2 via the dresser shaft 24. The dresser shaft 24 and the dressing disk 22 are movable up and down relative to the dresser swing arm 29. Furthermore, the dresser shaft 24 is connected to a disk rotation mechanism (including, for example, an electric motor) (not shown) arranged inside the dresser swing arm 29. This disk rotation mechanism is configured to rotate the dressing disk 22 about the axis of the dresser shaft 24 via the dresser shaft 24.

[0031] The dresser 20 is equipped with a pad height measuring device 32 that measures the height of the polishing surface 2a. The pad height measuring device 32 used in this embodiment is a contact-type displacement sensor. The pad height measuring device 32 is fixed to the support block 25, and a contact of the pad height measuring device 32 is in contact with the dresser swing arm 29. Since the support block 25 can move up and down integrally with the dresser shaft 24 and the dressing disk 22, the pad height measuring device 32 can move up and down integrally with the dresser shaft 24 and the dressing disk 22. Meanwhile, the vertical position of the dresser swing arm 29 is fixed. The pad height measuring device 32 moves up and down integrally with the dresser shaft 24 and the dressing disk 22 while the contact of the pad height measuring device 32 remains in contact with the dresser swing arm 29. Therefore, the pad height measuring device 32 can measure the displacement of the dressing disk 22 relative to the dresser swing arm 29.

[0032] The pad height measuring device 32 can measure the height of the polishing surface 2a via the dressing disk 22. That is, because the pad height measuring device 32 is connected to the dressing disk 22 via the dresser shaft 24, the pad height measuring device 32 can measure the height of the polishing surface 2a while the polishing pad 2 is being dressed. The height of the polishing surface 2a is the distance from a predetermined reference plane to the bottom surface of the dressing disk 22. The reference plane is an imaginary plane. For example, if the reference plane is the top surface of the polishing table 3, the height of the polishing surface 2a corresponds to the thickness of the polishing pad 2.

[0033] In this embodiment, a linear scale sensor is used as the pad height measuring device 32, but in one embodiment, a non-contact sensor such as a laser sensor, an ultrasonic sensor, or an eddy current sensor may be used as the pad height measuring device 32. Furthermore, in one embodiment, the pad height measuring device 32 may be fixed to the dresser swing arm 29 and arranged to measure the displacement of the support block 25. Even in this case, the pad height measuring device 32 can measure the displacement of the dressing disk 22 relative to the dresser swing arm 29.

[0034] In the above-described embodiment, the pad height measuring device 32 is configured to indirectly measure the height of the polishing surface 2a from the position of the dressing disk 22 when it is in contact with the polishing surface 2a, but the configuration of the pad height measuring device 32 is not limited to this embodiment as long as it can accurately measure the height of the polishing surface 2a. In one embodiment, the pad height measuring device 32 may be a non-contact sensor such as a laser sensor or an ultrasonic sensor that is placed above the polishing pad 2 and directly measures the height of the polishing surface 2a.

[0035] The polishing apparatus is equipped with a polishing control unit 60, and the pad height measuring device 32 is connected to the polishing control unit 60. The output signal of the pad height measuring device 32 (i.e., the measured value of the height of the polishing surface 2a) is sent to the polishing control unit 60.

[0036] The polishing head 1, polishing liquid supply nozzle 5, table motor 6, and dresser 20 of the polishing apparatus are electrically connected to a polishing control unit 60, and the operations of the polishing head 1, polishing liquid supply nozzle 5, table motor 6, and dresser 20 are controlled by the polishing control unit 60.

[0037] The dressing control unit 60 is composed of at least one computer. The dressing control unit 60 includes a storage device 60a that stores a program for controlling the operation of the dressing machine, and a processing device 60b that executes calculations according to instructions included in the program. The storage device 60a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Examples of the processing device 60b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the dressing control unit 60 is not limited to these examples.

[0038] The substrate W is polished as follows. While the polishing table 3 and polishing head 1 are rotating in the directions indicated by the arrows in FIGS. 1 and 2, a polishing liquid is supplied from a polishing liquid supply nozzle 5 to the polishing surface 2a of the polishing pad 2 on the polishing table 3. A dressing disk 22 is disposed outside the polishing pad 2. While the substrate W is being rotated by the polishing head 1, the polishing head 1 presses the substrate W against the polishing surface 2a of the polishing pad 2 with the polishing liquid present on the polishing pad 2. The surface of the substrate 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 / or the polishing pad 2. The substrate W may then be water-polished while pure water is supplied onto the polishing pad 2 from a pure water nozzle (not shown).

[0039] After polishing of the substrate W is completed, the substrate W is moved outside the polishing pad 2 and transported to an apparatus for the next processing. Then, the polishing surface 2a of the polishing pad 2 is dressed by the dresser 20. Specifically, while the polishing pad 2 and the polishing table 3 are rotating, pure water is supplied to the polishing surface 2a from a pure water nozzle (not shown). The dressing disk 22 is placed on the polishing pad 2 and is brought into sliding contact with the polishing surface 2a of the polishing pad 2 while rotating. The dressing disk 22 dresses (conditions) the polishing surface 2a by slightly scraping off the polishing pad 2. The dressing of the polishing pad 2 by the dresser 20 may be performed every time one substrate W is polished, or may be performed every time a predetermined number of substrates W are polished.

[0040] The polishing pad 2 is typically made of polyurethane foam having numerous fine pores on its polishing surface 2a. Furthermore, the polishing surface 2a of the polishing pad 2 is formed with holes (also called perforations) and pad grooves with patterns such as lattice, spiral, and concentric circles. The polishing surface 2a of the polishing pad 2 gradually wears down with repeated polishing and dressing of the substrate W, and polishing debris and the like become clogged in the holes and pad grooves formed on the polishing surface 2a. Such changes in the surface texture of the polishing pad 2 reduce the polishing performance of the polishing pad 2, resulting in a reduced polishing rate during polishing of the substrate W. Therefore, to determine the appropriate time to replace the polishing pad 2, it is necessary to accurately measure the surface texture of the polishing pad 2. Therefore, the polishing apparatus of this embodiment further includes a surface texture measurement system 40 for measuring the surface texture of the polishing pad 2. In this specification, the holes and pad grooves formed in the polishing pad 2 are collectively referred to as "recesses."

[0041] As shown in FIGS. 1 and 2 , the surface texture measuring system 40 includes an optical measuring device 41 that measures the surface texture of the polishing surface 2 a of the polishing pad 2, a cover member 44 that faces the polishing surface 2 a of the polishing pad 2, and a transparent liquid supply line 45 that supplies a transparent liquid onto the polishing pad 2. The optical measuring device 41 is disposed above the polishing pad 2. The cover member 44 is disposed between the polishing pad 2 and the optical measuring device 41. The cover member 44 is smaller than the polishing pad 2 and is disposed so as to cover a portion of the polishing pad 2. The surface texture measuring system 40 is disposed in a position that does not contact the polishing head 1 or the dresser 20. Therefore, the surface texture measuring system 40 can measure the surface texture of the polishing pad 2 even while the polishing head 1 is polishing the substrate W or while the dresser 20 is dressing the polishing pad 2.

[0042] FIG. 3 is a diagram showing how an optical measuring device 41 measures the polishing surface 2a of a polishing pad 2. For the sake of explanation, a cover member 44 and a transparent liquid supply line 45 are omitted from FIG. 3. The optical measuring device 41 includes a measuring head 42 and a data processing unit 43. The measuring head 42 in this embodiment is a laser displacement meter that measures the distance from a preset reference plane to an object. The measuring head 42 includes a light source 42a that emits laser light and a light receiving unit 42b that receives reflected light from the object. The reference plane is an imaginary plane, for example, a plane that includes the bottom end of the measuring head 42.

[0043] The measuring head 42 is configured to measure the distance D1 to the polishing surface 2a of the polishing pad 2. The measuring head 42 is disposed above the polishing surface 2a of the polishing pad 2, and the lower end of the measuring head 42 faces the polishing surface 2a of the polishing pad 2. In this embodiment, the reference plane is set to a plane including the lower end of the measuring head 42. Therefore, the distance D1 is the distance from the lower end of the measuring head 42 to a measurement point MP on the polishing surface 2a. The measuring head 42 irradiates the polishing surface 2a of the polishing pad 2 with light (laser light) from the light source 42a and receives the reflected light from the polishing surface 2a at the light receiving unit 42b. The measuring head 42 measures the distance D1 to the measurement point MP on the polishing pad 2 based on the reflected light.

[0044] FIG. 4 is a diagram showing multiple measurement points MP on the polishing surface 2a of the polishing pad 2. The measurement head 42 irradiates the polishing surface 2a of the rotating polishing pad 2 with light at predetermined time intervals (e.g., every 5 milliseconds) and measures the distance D1 to the polishing surface 2a of the polishing pad 2 based on the light reflected from the polishing surface 2a. The measurement head 42 is connected to an operation control unit 70 that controls the operation of the surface texture measuring system 40 (described later). When the operation control unit 70 issues a command to the measurement head 42, the measurement head 42 irradiates the polishing surface 2a of the polishing pad 2 with light. As shown in FIG. 4, the multiple measurement points MP are positioned at equal intervals on the circumference of a circle centered on the center of rotation O of the polishing pad 2. The measurement head 42 measures the distance D1 to the polishing surface 2a at the multiple measurement points MP by performing continuous measurements for a predetermined period of time. In one embodiment, multiple measured values ​​of the distance D1 at each of the multiple measurement points MP may be obtained in one continuous measurement. One continuous measurement may be performed each time one substrate W is polished, or may be performed each time a predetermined number of substrates W are polished.

[0045] FIG. 5 is a graph showing the relationship between the distance D1 measured at multiple measurement points MP and the measurement time T. In FIG. 5, the vertical axis represents the distance D1, and the horizontal axis represents the measurement time T. The graph shown in FIG. 5 was obtained by rotating the polishing pad 2 and measuring multiple measurement points MP on the polishing surface 2a with the measurement head 42 in one continuous measurement. At the time of measurement, the polishing pad 2 was in an initial state of use, with no wear. Measurement values ​​for the distance D1 near the value La were obtained when the measurement head 42 measured the distance D1 to a flat portion of the polishing surface 2a where no recesses 2b were formed, as shown in FIG. 6(a). Measurement values ​​for the distance D1 near the value Lb were obtained when the measurement head 42 measured the distance D1 to the bottom of the recesses 2b formed on the polishing surface 2a, as shown in FIG. 6(b).

[0046] As shown in Fig. 7(a), as the polishing of the substrate W and the dressing of the polishing pad 2 are repeated, the polishing pad 2 wears from the polishing surface 2a-1 before wear to the polishing surface 2a-2. The relationship between the measured value La1 of the distance D1 before wear and the measured value La2 of the distance D1 after wear is La1 < La2. That is, as the polishing pad 2 wears, the numerical value of the distance D1 corresponding to the measured value La shown in Fig. 5 increases.

[0047] Also, as shown in Fig. 7(b), as the polishing of the substrate W and the dressing of the polishing pad 2 are repeated, the recess 2b formed in the polishing surface 2a of the polishing pad 2 is clogged with polishing debris or the like. When the recess 2b clogged with polishing debris is measured by the measurement head 42, the light irradiated from the measurement head 42 is reflected on the surface of the polishing debris in the recess 2b. The relationship between the measured value Lb1 of the distance D1 to the bottom of the recess 2b before the polishing debris is clogged and the measured value Lb2 of the distance D1 to the surface of the polishing debris clogged in the recess 2b is Lb1 > Lb2. That is, as the recess 2b of the polishing pad 2 is clogged with polishing debris or the like, the numerical value of the distance D1 corresponding to the measured value Lb shown in Fig. 5 decreases.

[0048] Fig. 8 is a graph showing the relationship between the distance D1 and the measurement time T that change with the passage of the use time of the polishing pad 2. Fig. 8 plots the relationship between the measured value of the distance D1 and the measurement time T obtained from a plurality of consecutive measurements taken from the initial stage to the final stage of the use of the polishing pad 2. Fig. 8 may also plot the relationship between the average value of the measured values La and Lb obtained from one continuous measurement and the measurement time T. In Fig. 8, the vertical axis represents the distance D1, and the horizontal axis represents the measurement time T. As described with reference to Fig. 7(a), as the use time of the polishing pad 2 elapses, the flat portion of the polishing pad 2 wears. As shown in Fig. 8, the measured value of the distance D1 increases from the measured value La1 when the polishing pad 2 is not worn (time T1) to the measured value La2 when the polishing pad 2 is worn (time T2). Therefore, the degree of wear of the polishing pad 2 can be estimated from the change in the measured value of the distance D1.

[0049] 7(b), as the polishing pad 2 is used for a longer period of time, polishing debris and the like become clogged in the recesses 2b of the polishing pad 2. Therefore, as shown in FIG. 8, the measured value of the distance D1 decreases from a measured value Lb1 when the polishing pad 2 is not worn (time T1) to a measured value Lb2 when the polishing pad 2 has worn (time T2). Therefore, the degree of clogging of the recesses 2b of the polishing pad 2 can be estimated from the change in the measured value of the distance D1.

[0050] The measuring head 42 is connected to a data processing unit 43. The data processing unit 43 is composed of at least one computer. The measured value of the distance D1 acquired by the measuring head 42 is sent to the data processing unit 43. The data processing unit 43 measures the surface texture of the polishing pad 2 by processing data on the relationship between the distance D1 and the measurement time T as shown in FIGS. 5 and 8 based on the measured value of the distance D1 sent from the measuring head 42.

[0051] In this way, the optical measurement device 41 can measure the surface texture of the polishing pad 2. Measuring the surface texture of the polishing pad 2 includes estimating the degree of wear of the polishing pad 2 and / or estimating the degree of clogging of the recesses 2b of the polishing pad 2. In one embodiment, measuring the surface texture of the polishing pad 2 includes measuring the surface roughness of the polishing surface 2a of the polishing pad 2. The measurement results of the surface texture of the polishing pad 2 are sent to the operation control unit 70 connected to the data processing unit 43. The operation control unit 70 determines when to replace the polishing pad 2, which will be described later.

[0052] 1, the surface texture measuring system 40 may further include a measuring head moving mechanism 47 connected to the measuring head 42. The measuring head moving mechanism 47 is configured to be able to move the measuring head 42 in the radial direction of the polishing table 3 and the polishing pad 2. The measuring head moving mechanism 47 is connected to an operation control unit 70, which will be described later, and the operation of the measuring head moving mechanism 47 is controlled by the operation control unit 70.

[0053] In one embodiment, the measurement head 42 may be moved in the radial direction by the measurement head moving mechanism 47 while measuring the surface texture of the polishing pad 2. The measurement head moving mechanism 47 includes a measurement head arm 48 that supports the measurement head 42, and an actuator 49 connected to the measurement head arm 48. The actuator 49 is disposed outside the polishing table 3. The actuator 49 is configured by a combination of a motor and a torque transmission mechanism (including, for example, gears), or the like.

[0054] Measurement of the surface texture of the polishing pad 2 is performed during polishing of the substrate W with a polishing liquid or pure water, during dressing of the polishing pad 2, after dressing of the polishing pad 2 and before polishing the next substrate W, during and after the conditioning process of the polishing pad 2 using a conditioning substrate, etc. During measurement, if polishing liquid or polishing debris is present in the optical path of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a, the surface texture of the polishing pad 2 cannot be accurately measured. Therefore, the surface texture measurement system 40 of this embodiment fills the space between the cover member 44 and the polishing surface 2a of the polishing pad 2 with a transparent liquid, removing polishing liquid and polishing debris present in the optical path during measurement, thereby accurately measuring the surface texture.

[0055] FIG. 9 is a schematic diagram illustrating one embodiment of a surface texture measurement system 40. A cover member 44 is disposed between the polishing pad 2 and an optical measurement device 41 (measurement head 42). The cover member 44 has an opposing surface 44c parallel to the polishing surface 2a of the polishing pad 2. The cover member 44 is spaced apart from the polishing surface 2a of the polishing pad 2 (i.e., it is not in contact with the polishing surface 2a). The cover member 44 has a light-transmitting portion 44a on the optical path of the light irradiated by the measurement head 42 and the light reflected from the polishing surface 2a. The light-transmitting portion 44a is the portion indicated by the dashed line in FIG. 9 through which the light irradiated by the measurement head 42 and the light reflected from the polishing surface 2a pass. The light-transmitting portion 44a is made of a transparent material that transmits the light irradiated by the measurement head 42 and the light reflected from the polishing surface 2a. In this embodiment, the cover member 44 is a transparent plate, and the entire cover member 44, including the light-transmitting portion 44a, is made of a transparent material.

[0056] In one embodiment, the light-transmitting portion 44a of the cover member 44 may be made of a transparent material, and the remaining portion may be made of a material that does not transmit light. Examples of materials for the light-transmitting portion 44a include quartz glass, acrylic resin, polycarbonate resin, and polyvinyl chloride resin. The optical measuring device 41 irradiates the polishing surface 2a of the polishing pad 2 with light through the light-transmitting portion 44a of the cover member 44, receives the light reflected from the polishing surface 2a through the light-transmitting portion 44a, and measures the surface texture of the polishing pad 2 based on the reflected light.

[0057] The cover member 44 is provided with an injection port 44b located upstream of the light transmitting portion 44a in the rotation direction of the polishing pad 2. That is, the injection port 44b is located upstream of the optical paths of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a. In this embodiment, the injection port 44b is located upstream of the measurement head 42 of the optical measurement device 41.

[0058] The inlet 44b extends vertically through the cover member 44 and is inclined downward toward the inside of the cover member 44. In one embodiment, the inlet 44b may not be inclined, but may extend vertically through the cover member 44 relative to the opposing surface 44c. As shown in FIG. 1, the inlet 44b is a slit that has a rectangular shape when viewed from above. The inlet 44b is not limited to this embodiment and may be an opening that has a circular or elliptical shape when viewed from above.

[0059] The transparent liquid supply line 45 is connected to the inlet 44b of the cover member 44 and is configured to supply transparent liquid onto the polishing pad 2 through the inlet 44b. As shown in Fig. 9, the entire cover member 44 is spaced apart from the polishing surface 2a of the polishing pad 2, and a gap through which the transparent liquid flows exists between the opposing surface 44c of the cover member 44 and the polishing surface 2a of the polishing pad 2. The transparent liquid supplied from the transparent liquid supply line 45 flows through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 in the rotation direction of the polishing pad 2.

[0060] The gap between the opposing surface 44c of the cover member 44 and the polishing surface 2a of the polishing pad 2 is filled with a flow of transparent liquid. In particular, the entire gap between the light-transmitting portion 44a and the polishing surface 2a of the polishing pad 2 is filled with a flow of transparent liquid. With this configuration, bubbles and gas layers (gas-liquid interfaces) that cause disturbances in optical measurement by the optical measurement device 41 are not present in the measurement light path, enabling stable measurement. Furthermore, since the injection port 44b is located directly above the gap between the opposing surface 44c of the cover member 44 and the polishing surface 2a of the polishing pad 2, transparent liquid can be smoothly supplied to the gap. When the transparent liquid flows into the gap, no disturbance occurs in the flow of the transparent liquid, preventing the generation of bubbles. The transparent liquid is, for example, pure water. The transparent liquid may be any transparent liquid, such as a KOH solution used in polishing liquids.

[0061] The surface texture measuring system 40 further includes a supply flow rate control valve 50 that can adjust the flow rate of the transparent liquid supplied from the transparent liquid supply line 45 to the inlet 44b, and a flow meter 51 that measures the flow rate of the transparent liquid flowing through the transparent liquid supply line 45. The supply flow rate control valve 50 and the flow meter 51 are attached to the transparent liquid supply line 45.

[0062] The surface texture measuring system 40 includes an operation control unit 70 that controls the operation of the surface texture measuring system 40. The supply flow rate control valve 50 is electrically connected to the operation control unit 70, and the operation of the supply flow rate control valve 50 is controlled by the operation control unit 70. In one embodiment, the supply flow rate control valve 50 may be manually operated.

[0063] The flow rate of the transparent liquid supplied from the transparent liquid supply line 45 to the inlet 44b is determined based on parameters such as the rotation speed of the polishing table 3, the distance from the polishing surface 2a to the opposing surface 44c of the cover member 44, the type of polishing pad 2 (such as the material of the polishing pad 2 and the shape of the recess formed on the polishing surface 2a), and the type of polishing liquid.

[0064] The flow rate of the transparent liquid supplied from the transparent liquid supply line 45 to the inlet 44b is a flow rate that allows the transparent liquid to sufficiently fill the gap between the opposing surface 44c of the cover member 44 and the polishing surface 2a of the polishing pad 2. If the flow rate of the transparent liquid supplied from the transparent liquid supply line 45 is too low, the transparent liquid will not be sufficiently supplied to the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2, resulting in the generation of air bubbles. If the flow rate of the transparent liquid is too high, the transparent liquid will flow too quickly in the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2, causing turbulence.

[0065] In one embodiment, supply flow rate data indicating the relationship between parameters such as the rotation speed of the polishing table 3, the distance from the polishing surface 2a to the opposing surface 44c of the cover member 44, the type of polishing pad 2, and the type of polishing liquid and the optimal flow rate of the transparent liquid supplied from the transparent liquid supply line 45 may be acquired in advance, and the supply flow rate data may be stored in the operation control unit 70. The operation control unit 70 is connected to a polishing control unit 60 that controls the operation of the polishing apparatus. The operation control unit 70 may control the operation of the supply flow rate adjustment valve 50 based on the parameters acquired from the polishing control unit 60 and the supply flow rate data.

[0066] For example, the operation control unit 70 may acquire from the polishing control unit 60 a measurement value of the height of the polishing surface 2a of the polishing pad 2 acquired by the pad height measuring device 32, and determine the flow rate of the transparent liquid based on the acquired measurement value of the height of the polishing surface 2a and the supply flow rate data. The operation control unit 70 may control the operation of the supply flow rate adjustment valve 50 so that the transparent liquid is supplied at an appropriate flow rate. Alternatively, the operation control unit 70 may determine the flow rate of the transparent liquid based on the distance D1 to the polishing surface 2a of the polishing pad 2 measured by the measuring head 42 of the optical measurement device 41, and control the operation of the supply flow rate adjustment valve 50.

[0067] In another embodiment, the operation control unit 70 may calculate the standard deviation of the surface texture measurement values ​​obtained by the optical measurement device 41, and if the standard deviation is greater than a predetermined threshold value (if the degree of variation is large), control the operation of the supply flow rate adjustment valve 50 to increase the flow rate of transparent liquid supplied from the transparent liquid supply line 45. Alternatively, if the surface texture measurement values ​​obtained by the optical measurement device 41 are smaller than a predetermined threshold value, the operation control unit 70 may control the operation of the supply flow rate adjustment valve 50 to increase the flow rate of transparent liquid supplied from the transparent liquid supply line 45.

[0068] As shown in FIG. 9, the surface texture measuring system 40 may further include a cover member height adjustment mechanism 53 that adjusts the height of the cover member 44. The cover member height adjustment mechanism 53 is connected to the cover member 44. The cover member height adjustment mechanism 53 may be configured, for example, by a combination of a servo motor and a ball screw mechanism. The cover member height adjustment mechanism 53 is electrically connected to the operation control unit 70. The operation control unit 70 may acquire from the polishing control unit 60 a measured value of the height of the polishing surface 2 a of the polishing pad 2 acquired by the pad height measuring device 32, and may adjust the height of the cover member 44 relative to the polishing surface 2 a of the polishing pad 2 using the cover member height adjustment mechanism 53 based on the measured value of the height of the polishing surface 2 a.

[0069] The height of the cover member 44 is the distance from the polishing surface 2a of the polishing pad 2 to the opposing surface 44c of the cover member 44. In one embodiment, the distance D2 from the polishing surface 2a of the polishing pad 2 to the opposing surface 44c of the cover member 44 is 5 mm or less. If the distance D2 from the polishing surface 2a of the polishing pad 2 to the opposing surface 44c of the cover member 44 is too small, transparent liquid does not easily flow between the cover member 44 and the polishing surface 2a of the polishing pad 2, and polishing liquid and polishing debris present in the optical path during measurement cannot be removed by the flow of transparent liquid. Furthermore, contact between the cover member 44 and the polishing surface 2a of the polishing pad 2 may damage the polishing pad 2. If the distance D2 from the polishing surface 2a of the polishing pad 2 to the opposing surface 44c of the cover member 44 is too large, transparent liquid easily leaks outside the cover member 44, making it difficult to sufficiently fill the space between the cover member 44 and the polishing surface 2a of the polishing pad 2 with transparent liquid.

[0070] The operation control unit 70 is composed of at least one computer. The operation control unit 70 includes a storage device 70a that stores a program for controlling the operation of the surface texture measurement system 40, and a processing device 70b that executes calculations according to instructions included in the program. The storage device 70a includes a main storage device such as a random access memory (RAM) and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Examples of the processing device 70b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the operation control unit 70 is not limited to these examples.

[0071] In one embodiment, the above-described data processing unit 43 may be configured integrally with the operation control unit 70. That is, the data processing unit 43 and the operation control unit 70 may be configured by at least one computer including a storage device in which a program is stored and a processing device that executes calculations in accordance with instructions included in the program.

[0072] In one embodiment, the dressing control unit 60 may be configured integrally with the operation control unit 70. That is, the dressing control unit 60 and the operation control unit 70 may be configured by at least one computer including a storage device storing a program and a processing device that executes calculations according to instructions included in the program.

[0073] According to this embodiment, the cover member 44 does not come into contact with the polishing pad 2, and a transparent liquid can be supplied to the optical path during measurement of the surface texture of the polishing pad 2, so that the polishing surface 2a of the polishing pad 2 is not damaged by the member during measurement. Furthermore, the surface texture measurement system 40 may be permanently installed in the polishing apparatus, and no time is required for preparation for measurement. Therefore, the surface texture of the polishing pad 2 can be measured even in a short time, such as before polishing the next substrate W to be processed.

[0074] FIG. 10 is a flowchart showing one embodiment of the process for measuring the surface texture of the polishing pad 2. In step S101, the polishing control unit 60 issues a command to the table motor 6 to rotate the polishing table 3 together with the polishing pad 2 while supporting the polishing pad 2. The polishing table 3 may already be rotating together with the polishing pad 2, for example, while the substrate W is being polished with the polishing liquid or pure water, while the polishing pad 2 is being dressed, after the polishing pad 2 has been dressed, and before the next substrate W to be processed is polished.

[0075] In step S102, the operation control unit 70 issues a command to the supply flow rate adjustment valve 50 to open the supply flow rate adjustment valve 50 and supply the transparent liquid onto the polishing pad 2 through the inlet 44b of the cover member 44. The gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 is filled with the transparent liquid. In step S103, the operation control unit 70 issues a command to the measurement head 42 of the optical measuring device 41 to irradiate light onto the polishing surface 2a of the polishing pad 2 through the light transmitting portion 44a of the cover member 44, and receives reflected light from the polishing surface 2a through the light transmitting portion 44a.

[0076] In step S104, the optical measuring device 41 measures the surface texture of the polishing pad 2 based on the light reflected from the polishing surface 2a. More specifically, the data processing unit 43 of the optical measuring device 41 measures the surface texture of the polishing pad 2 by processing data on the relationship between the distance D1 (see FIG. 3) measured based on the reflected light sent from the measuring head 42 and the measurement time T. The measurement results of the surface texture of the polishing pad 2 are sent to the operation control unit 70. In step S105, the operation control unit 70 determines whether it is time to replace the polishing pad 2 based on the measurement results of the surface property of the polishing pad 2. If it is determined that it is time to replace the polishing pad 2, an alarm may be issued to prompt the user to replace the polishing pad 2 (step S106).

[0077] 11 is a flowchart showing another embodiment of the process for measuring the surface texture of the polishing pad 2. In this embodiment, the surface texture of the polishing pad 2 is measured to determine whether the break-in process of the polishing pad 2 has been completed. In step S201, a new (brand new) polishing pad 2 is attached to the polishing table 3. The polishing control unit 60 issues a command to the table motor 6 to rotate the polishing table 3 together with the polishing pad 2 while supporting the new polishing pad 2.

[0078] In step S202, a conditioning substrate (dummy substrate) is polished to condition the polishing pad 2. Specifically, the polishing control unit 60 issues a command to the polishing liquid supply nozzle 5 to supply a polishing liquid to the polishing surface 2a of the polishing pad 2 on the polishing table 3. The polishing control unit 60 then issues a command to the polishing head 1 to rotate the polishing head 1 and press the conditioning substrate, held on the underside of the polishing head 1, against the polishing surface 2a of the polishing pad 2. A new polishing pad 2 has unstable surface roughness and water absorption properties, and the surface properties change during polishing of multiple substrates, making it impossible to achieve stable polishing performance. Therefore, by polishing the conditioning substrate (dummy substrate), the surface properties of the polishing pad 2 are stabilized and the polishing performance of the polishing pad 2 is improved. This process for a new polishing pad 2 is referred to as a "conditioning process." After the conditioner process is completed, the polishing pad 2 has uniform and stable surface properties.

[0079] Steps S203 to S205 are the same as steps S102 to S104 in FIG. 10, so a duplicated description will be omitted. In step S206, the operation control unit 70 determines whether the break-in process of the polishing pad 2 has been completed based on the measurement results of the surface texture of the polishing pad 2. If it is determined that the break-in process is incomplete, the process returns to step S202, and polishing of the break-in process substrate is further performed. If it is determined that the break-in process is completed, polishing of the break-in process substrate is terminated. Thereafter, the substrate W to be actually processed is held by the polishing head 1, and the substrate W is polished using the polishing pad 2. The measurement of the surface texture of the new polishing pad 2 may be performed either during or after polishing of the break-in process substrate.

[0080] Fig. 12 is a schematic diagram showing another embodiment of the surface texture measurement system 40. Fig. 13 is a top view of the surface texture measurement system 40 shown in Fig. 12. The configuration of this embodiment not specifically described is the same as the embodiment described with reference to Fig. 9, so redundant description will be omitted. The cover member height adjustment mechanism 53 is not shown in Figs. 12 and 13. In this embodiment, the cover member 44 is further provided with a suction port 44d, and the surface texture measurement system 40 further includes a transparent liquid suction line 55 connected to the suction port 44d.

[0081] Suction port 44d is located downstream of injection port 44b and light transmitting portion 44a in the rotation direction of polishing pad 2. That is, suction port 44d is located downstream of the optical paths of light emitted from measurement head 42 and light reflected from polishing surface 2a. In this embodiment, suction port 44d is located downstream of measurement head 42 of optical measurement device 41.

[0082] The suction port 44d extends vertically through the cover member 44 and is inclined downward toward the inside of the cover member 44. In one embodiment, the suction port 44d may not be inclined, but may extend vertically through the opposite surface 44c of the cover member 44. As shown in Fig. 13, the suction port 44d is a slit that has a rectangular shape when viewed from above. The suction port 44d is not limited to this embodiment and may be an opening that has a circular or elliptical shape when viewed from above.

[0083] The transparent liquid suction line 55 is configured to suck the transparent liquid flowing through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 through the suction port 44d. The transparent liquid supplied from the transparent liquid supply line 45 flows through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 in the rotation direction of the polishing pad 2 and is sucked by the transparent liquid suction line 55. More specifically, the transparent liquid supplied from the transparent liquid supply line 45 through the injection port 44b flows from the injection port 44b through the light transmitting portion 44a toward the suction port 44d and is sucked by the transparent liquid suction line 55 through the suction port 44d. The sucked transparent liquid is discharged out of the transparent liquid suction line 55. In one embodiment, the flow rate of the transparent liquid supplied from the transparent liquid supply line 45 is greater than the flow rate of the transparent liquid sucked by the transparent liquid suction line 55.

[0084] According to this embodiment, a flow of transparent liquid is formed in the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 from the inlet 44b toward the suction port 44d, so that the optical path can be filled with transparent liquid when measuring the surface texture of the polishing pad 2. Furthermore, by sucking the transparent liquid on the polishing pad 2 through the transparent liquid suction line 55, it is possible to prevent the transparent liquid from leaking out of the cover member 44. Therefore, when measuring the surface texture of the polishing pad 2 while polishing the substrate W with the polishing liquid, it is possible to prevent the polishing liquid from being diluted with the transparent liquid. Furthermore, by measuring the surface texture of the polishing pad 2 while polishing the substrate W with the polishing liquid, it is possible to measure the surface texture of the polishing pad 2 in a state where the substrate W is actually being polished using the polishing liquid.

[0085] The surface texture measuring system 40 further includes a suction flow rate adjustment valve 57 that can adjust the flow rate of the transparent liquid sucked by the transparent liquid suction line 55 through the suction port 44d, and a flow meter 58 that measures the flow rate of the transparent liquid flowing through the transparent liquid suction line 55. The suction flow rate adjustment valve 57 and the flow meter 58 are attached to the transparent liquid suction line 55. The suction flow rate adjustment valve 57 is electrically connected to an operation control unit 70, and the operation of the suction flow rate adjustment valve 57 is controlled by the operation control unit 70. In one embodiment, the suction flow rate adjustment valve 57 may be manual.

[0086] The operation control unit 70 issues commands to the supply flow rate adjustment valve 50 and the suction flow rate adjustment valve 57 to open them, and while supplying transparent liquid onto the polishing pad 2 through the injection port 44b of the cover member 44, the transparent liquid on the polishing pad 2 is sucked through the suction port 44d by the transparent liquid suction line 55. Furthermore, the operation control unit 70 issues commands to the optical measurement device 41 to measure the surface properties of the polishing pad 2.

[0087] The flow rate of the transparent liquid sucked by the transparent liquid suction line 55 through the suction port 44d is determined based on parameters such as the rotation speed of the polishing table 3, the distance from the polishing surface 2a to the opposing surface 44c of the cover member 44, the type of polishing pad 2 (the material of the polishing pad 2, the shape of the recess formed on the polishing surface 2a, etc.), the type of polishing liquid, and the flow rate of the transparent liquid supplied from the transparent liquid supply line 45.

[0088] In one embodiment, suction flow rate data indicating the relationship between parameters such as the rotation speed of the polishing table 3, the distance from the polishing surface 2a to the opposing surface 44c of the cover member 44, the type of polishing pad 2, the type of polishing liquid, and the flow rate of the transparent liquid supplied from the transparent liquid supply line 45, and the optimal flow rate of the transparent liquid to be sucked through the transparent liquid suction line 55, may be acquired in advance, and the suction flow rate data may be stored in the operation control unit 70. The operation control unit 70 is connected to a polishing control unit 60 that controls the operation of the polishing apparatus. The operation control unit 70 may control the operation of the suction flow rate adjustment valve 57 based on the parameters acquired from the polishing control unit 60 and the suction flow rate data.

[0089] In another embodiment, the operation control unit 70 may calculate the standard deviation of the surface texture measurement values ​​obtained by the optical measurement device 41, and, if the standard deviation is greater than a predetermined threshold (if the degree of variation is large), control the operation of the supply flow rate adjustment valve 50 and / or the suction flow rate adjustment valve 57 to adjust the flow rate of transparent liquid supplied from the transparent liquid supply line 45 and / or the flow rate of transparent liquid sucked by the transparent liquid suction line 55. Alternatively, the operation control unit 70 may control the operation of the supply flow rate adjustment valve 50 and / or the suction flow rate adjustment valve 57 to adjust the flow rate of transparent liquid supplied from the transparent liquid supply line 45 and / or the flow rate of transparent liquid sucked by the transparent liquid suction line 55 when the surface texture measurement values ​​obtained by the optical measurement device 41 are smaller than a predetermined threshold.

[0090] The appropriate flow rate of the transparent liquid sucked by the transparent liquid suction line 55 through the suction port 44d is a flow rate at which the transparent liquid sufficiently fills the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2. If the flow rate of the transparent liquid sucked by the transparent liquid suction line 55 is too low, it is not possible to prevent the transparent liquid from leaking out of the cover member 44. If the flow rate of the transparent liquid is too high, more transparent liquid than necessary will be sucked from the polishing pad 2, and the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 will not be filled with transparent liquid. Furthermore, the flow of transparent liquid from the injection port 44b toward the suction port 44d will be disturbed, causing the generation of bubbles.

[0091] Figure 14 is a schematic diagram showing yet another embodiment of the surface texture measuring system 40. The configuration of this embodiment not specifically described is the same as the embodiment described with reference to Figure 12, so duplicated description will be omitted. The surface texture measuring system 40 of this embodiment further includes an imaging device 72. The imaging device 72 is disposed above the cover member 44 and adjacent to the measuring head 42. The imaging device 72 is a camera equipped with an image sensor such as a CCD sensor or a CMOS sensor.

[0092] The imaging device 72 is configured to generate an image of the monitoring region MR. The monitoring region MR is the region indicated by the dashed-dotted line in FIG. 14 and includes measurement points MP on the polishing surface 2a of the polishing pad 2 where light is irradiated and reflected by the optical measurement device 41. The monitoring region MR may include an inlet 44b and an inlet 44d in the opposing surface 44c of the cover member 44. In one embodiment, the surface texture measurement system 40 may further include an illuminator for illuminating the monitoring region MR on the polishing surface 2a.

[0093] The imaging device 72 is electrically connected to the operation control unit 70. The image of the monitoring region MR generated by the imaging device 72 is sent to the operation control unit 70. The operation control unit 70 determines the state of the transparent liquid flowing between the cover member 44 and the polishing surface 2a of the polishing pad 2 from the acquired image of the monitoring region MR. More specifically, the operation control unit 70 determines whether the flow of the transparent liquid is disturbed based on the image of the monitoring region MR. For example, the operation control unit 70 determines the state of the transparent liquid by determining whether there are any bubbles or air layers between the cover member 44 and the polishing surface 2a of the polishing pad 2, the transparency of the transparent liquid (whether it is cloudy due to the polishing liquid, etc.), etc.

[0094] The operation control unit 70 is configured to control the operation of the supply flow rate adjustment valve 50 and the suction flow rate adjustment valve 57 based on the image of the monitoring region MR. In one embodiment, the operation control unit 70 determines whether or not there are bubbles on the acquired image of the monitoring region MR. If the operation control unit 70 determines that the flow of the transparent liquid is turbulent, it adjusts the supply flow rate adjustment valve 50 to increase the flow rate of the transparent liquid supplied from the transparent liquid supply line 45. For example, the operation control unit 70 may adjust the supply flow rate adjustment valve 50 to increase the flow rate of the transparent liquid supplied from the transparent liquid supply line 45 when the number of bubbles on the acquired image of the monitoring region MR exceeds a predetermined threshold.

[0095] In another embodiment, the operation control unit 70 determines whether the entire gap between the light-transmitting portion 44a of the cover member 44 and the polishing surface 2a of the polishing pad 2 is filled with transparent liquid based on the acquired image of the monitoring area MR, and if it determines that the gap is not filled with transparent liquid, it may adjust the supply flow rate control valve 50 to increase the flow rate of transparent liquid supplied from the transparent liquid supply line 45, or adjust the suction flow rate control valve 57 to reduce the flow rate of transparent liquid sucked by the transparent liquid suction line 55.

[0096] In still another embodiment, the operation control unit 70 may be configured to issue an alarm when an abnormality in the flow of transparent liquid on the polishing pad 2 is detected based on the image of the monitoring area MP. More specifically, when controlling the operation of the supply flow rate adjustment valve 50 and / or the suction flow rate adjustment valve 57 as described above, the operation control unit 70 may be configured to issue an alarm when the opening degree of the supply flow rate adjustment valve 50 and / or the suction flow rate adjustment valve 57 reaches a lower limit or an upper limit.

[0097] The imaging device 72 shown in Fig. 14 can also be applied to the embodiment shown in Fig. 9. In this case, the operation control unit 70 is configured to control the operation of the supply flow rate adjustment valve 50 based on an image of the monitoring region MR.

[0098] The surface texture measuring system 40 of the embodiment described so far is configured to include a laser displacement meter as the measuring head 42 of the optical measuring device 41 and to measure the surface shape of the polishing pad 2 based on the distance from the lower end of the measuring head 42 to the polishing surface 2a of the polishing pad 2, but the configuration of the optical measuring device 41 is not limited to this. Fig. 15 is a schematic diagram showing another embodiment of the optical measuring device 41. The optical measuring device 41 shown in Fig. 15 includes a first measuring head 75 having a light source 75a, a second measuring head 76 having a light receiving unit 76a, and a data processing unit 43.

[0099] The first measurement head 75 irradiates the polishing surface 2a of the polishing pad 2 with light (laser light) from the light source 75a, and receives the light reflected from the polishing surface 2a at the light receiving unit 76a of the second measurement head 76. The light receiving unit 76a is composed of either a linear or planar CCD element or CMOS element with dimensions that allow it to receive at least the fourth-order diffracted light or up to the seventh-order diffracted light of the light reflected from the polishing surface 2a. The second measurement head 76 is connected to the data processing unit 43. The measured values ​​by the second measurement head 76 are sent to the data processing unit 43 and analyzed.

[0100] The laser light irradiated onto the polishing surface 2a not only undergoes specular reflection, but also undergoes diffraction and is reflected at a wide angle depending on the surface texture of the polishing pad 2. In other words, by receiving and analyzing not only the specular reflection component but also the light reflected at a wide angle, information on the surface texture of the polishing pad 2 can be obtained. In order to receive this light reflected at a wide angle, a linear or planar light receiving element is required. Since it is known that the surface texture of the polishing pad 2 is preferably included in seventh-order diffracted light, and in practical use, up to fourth-order diffracted light, a light receiving element large enough to receive diffracted light in this range is required. In this way, the optical measuring device 41 can measure the surface texture of the polishing pad 2.

[0101] Fig. 16 is a schematic diagram showing yet another embodiment of the optical measurement device 41. The optical measurement device 41 shown in Fig. 16 includes a first measurement head 77 having a light source 77a, a second measurement head 78 having a light receiving unit 78a, and a data processing unit 43.

[0102] The first measurement head 77 irradiates light (laser light) from the light source 77a onto the polishing surface 2a of the polishing pad 2, and the light reflected from the polishing surface 2a is received by the light receiving unit 78a of the second measurement head 78. The light reflected from the polishing surface 2a includes scattered light of orders 0 to n (n is a predetermined natural number) of the reflected light. The light receiving unit 78a is configured to be able to receive scattered light of orders 0 to about 7 reflected from the polishing surface 2a.

[0103] The second measurement head 78 is connected to the data processing unit 43. The measurement values ​​obtained by the second measurement head 78 are sent to the data processing unit 43. The data processing unit 43 performs a spatial Fourier transform (or a spatial fast Fourier transform) to generate a spectrum of the scattered light. The data processing unit 43 performs known processing on this spectrum of the scattered light to calculate a surface texture index and measure the surface texture of the polishing pad 2. Known processing for calculating the surface texture index includes, for example, calculating the integral of the scattered light intensity in a specific spatial wavelength region, or calculating the ratio of the integral in a second spatial wavelength region to the integral in a first spatial wavelength region. In this way, the optical measurement device 41 can measure the surface texture of the polishing pad 2.

[0104] Fig. 17 is a schematic diagram showing yet another embodiment of the optical measurement device 41. The optical measurement device 41 shown in Fig. 17 includes a pad imaging device 73 that generates an image of the polishing surface 2a of the polishing pad 2, and an illuminator 74 that illuminates the polishing surface 2a. The pad imaging device 73 is a camera equipped with an image sensor such as a CCD sensor or a CMOS sensor. The imaging device 72 described with reference to Fig. 14 may be used as the pad imaging device 73.

[0105] The illuminator 74 is configured to irradiate the polishing surface 2a of the polishing pad 2 with light. The pad imaging device 73 is configured to generate an image of an imaging area IR based on light reflected from the polishing surface 2a. The imaging area IR is the area indicated by the dashed dotted line in FIG. 17 , and is an area including a measurement point MP on the polishing surface 2a that is illuminated by the illuminator 74 through the light-transmitting portion 44a of the optical measurement device 41 and an image of which is generated through the light-transmitting portion 44a of the cover member 44. The imaging area IR may include the light-transmitting portion 44a of the cover member 44. In this embodiment, the illuminator 74 is disposed so as to irradiate light perpendicular to the polishing surface 2a. However, the installation angle of the illuminator 74 with respect to the polishing surface 2a is arbitrary as long as it can illuminate the imaging area IR, and is not limited to this embodiment.

[0106] The image of the imaging area IR includes the surface properties of the polishing pad 2, such as the state of recesses formed on the polishing surface 2a and the state of the polishing surface 2a (such as peeling or damage on the polishing surface 2a). Therefore, the optical measurement device 41 of this embodiment can measure the surface properties of the polishing pad 2 by generating an image of the imaging area IR. The pad imaging device 73 is electrically connected to the operation control unit 70. The measurement results of the surface properties of the polishing pad 2, i.e., the image of the imaging area IR generated by the pad imaging device 73, are sent to the operation control unit 70. The operation control unit 70 determines whether it is time to replace the polishing pad 2 based on the image of the imaging area IR.

[0107] In one embodiment, the operation control unit 70 may determine that it is time to replace the polishing pad 2 when no recesses on the polishing surface 2a appear in the image of the imaged area IR. In one embodiment, the operation control unit 70 may determine that it is time to replace the polishing pad 2 when peeling or damage to the polishing surface 2a appears in the image of the imaged area IR. In one embodiment, the operation control unit 70 may analyze the surface texture of the polishing pad 2 contained in the image of the imaged area IR by performing known image processing (e.g., binarization processing) on ​​the image of the imaged area IR, and determine when to replace the polishing pad 2. This image processing may be performed by a data processing unit 43 (not shown in FIG. 17 ) connected to the pad imaging device 73, and the measurement results of the surface texture of the polishing pad 2 analyzed by the data processing unit 43 may be sent to the operation control unit 70.

[0108] The optical measurement device 41 shown in FIGS. 15 to 17 can be applied to any of the surface texture measurement systems 40 shown in FIGS. 9, 12, 14, and FIGS. 18 to 20 described below.

[0109] As described above, the measurement of the surface properties of the polishing pad 2 by the optical measuring device 41 may be performed while the polishing pad 2 is rotating, or while the rotation of the polishing pad 2 is stopped.

[0110] FIG. 18 is a schematic diagram illustrating yet another embodiment of the surface texture measurement system 40. The configuration of this embodiment, unless otherwise specified, is the same as the embodiment described with reference to FIG. 12 , and therefore redundant description will be omitted. In this embodiment, as shown in FIG. 18 , the injection port 44b of the cover member 44 is located downstream of the light-transmitting portion 44a in the rotation direction of the polishing pad 2, and the suction port 44d is located upstream of the injection port 44b and the light-transmitting portion 44a in the rotation direction of the polishing pad 2. That is, the injection port 44b is located downstream of the optical path of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a, and the suction port 44d is located upstream of the optical path of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a. In this embodiment, the injection port 44b is located downstream of the measurement head 42 of the optical measurement device 41, and the suction port 44d is located upstream of the measurement head 42 of the optical measurement device 41.

[0111] In this embodiment, the transparent liquid supplied from the transparent liquid supply line 45 flows through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 in the direction opposite to the rotation direction of the polishing pad 2, and is sucked by the transparent liquid suction line 55. More specifically, the transparent liquid supplied from the transparent liquid supply line 45 through the inlet 44b flows from the inlet 44b through the light transmitting portion 44a toward the suction port 44d, and is sucked by the transparent liquid suction line 55 through the suction port 44d. The sucked transparent liquid is discharged outside the transparent liquid suction line 55.

[0112] In one embodiment, the surface texture measuring system 40 does not include the transparent liquid suction line 55, and the cover member 44 does not need to have the suction port 44d. In this case, the cover member 44 has an inlet 44b located downstream of the light transmitting portion 44a in the rotation direction of the polishing pad 2, and the transparent liquid supplied from the transparent liquid supply line 45 flows through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 in the direction opposite to the rotation direction of the polishing pad 2. In this case, the entire gap between the light transmitting portion 44a and the polishing surface 2a of the polishing pad 2 is filled with transparent liquid.

[0113] Figure 19 is a schematic diagram showing yet another embodiment of the surface texture measuring system 40. Configurations of this embodiment that are not particularly described are the same as those of the embodiment described with reference to Figure 12, so redundant description will be omitted. The surface texture measuring system 40 of this embodiment has a first transparent liquid supply line 45-1 and a second transparent liquid supply line 45-2 instead of the transparent liquid supply line 45 and the transparent liquid suction line 55. The cover member 44 has a first injection port 44b-1 and a second injection port 44b-2 instead of the injection port 44b and the suction port 44d.

[0114] The first injection port 44b-1 is located upstream of the light transmitting portion 44a in the rotation direction of the polishing pad 2, and the second injection port 44b-2 is located downstream of the first injection port 44b-1 and the light transmitting portion 44a in the rotation direction of the polishing pad 2. That is, the first injection port 44b-1 is located upstream of the optical path of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a, and the second injection port 44b-2 is located downstream of the optical path of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a. In this embodiment, the first injection port 44b-1 is located upstream of the measurement head 42 of the optical measurement device 41, and the second injection port 44b-2 is located downstream of the measurement head 42 of the optical measurement device 41.

[0115] The first transparent liquid supply line 45-1 is connected to a first inlet 44b-1 of the cover member 44, and is configured to supply transparent liquid onto the polishing pad 2 through the first inlet 44b-1. The second transparent liquid supply line 45-2 is connected to a second inlet 44b-2 of the cover member 44, and is configured to supply transparent liquid onto the polishing pad 2 through the second inlet 44b-2.

[0116] The surface texture measurement system 40 further includes a first supply flow rate control valve 50-1 that can adjust the flow rate of the transparent liquid supplied from the first transparent liquid supply line 45-1 to the first inlet 44b-1, and a first flow meter 51-1 that measures the flow rate of the transparent liquid flowing through the first transparent liquid supply line 45-1. The first supply flow rate control valve 50-1 and the first flow meter 51-1 are attached to the first transparent liquid supply line 45-1. Similarly, the surface texture measurement system 40 further includes a second supply flow rate control valve 50-2 that can adjust the flow rate of the transparent liquid supplied from the second transparent liquid supply line 45-2 to the second inlet 44b-2, and a second flow meter 51-2 that measures the flow rate of the transparent liquid flowing through the second transparent liquid supply line 45-2. The second supply flow rate control valve 50-2 and the second flow meter 51-2 are attached to the second transparent liquid supply line 45-2.

[0117] The first supply flow rate adjustment valve 50-1 and the second supply flow rate adjustment valve 50-2 are electrically connected to the operation control unit 70, and the operations of the first supply flow rate adjustment valve 50-1 and the second supply flow rate adjustment valve 50-2 are controlled by the operation control unit 70. In one embodiment, the first supply flow rate adjustment valve 50-1 and the second supply flow rate adjustment valve 50-2 may be manual.

[0118] The transparent liquid supplied from the first transparent liquid supply line 45-1 flows through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 in the direction of rotation of the polishing pad 2. The transparent liquid supplied from the second transparent liquid supply line 45-2 flows through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 in the direction opposite to the direction of rotation of the polishing pad 2.

[0119] The surface texture measurement system 40 is configured to supply transparent liquid from at least one of a first transparent liquid supply line 45-1 and a second transparent liquid supply line 45-2. The surface texture measurement system 40 selectively switches the line supplying the transparent liquid between the first transparent liquid supply line 45-1 and the second transparent liquid supply line 45-2 using a first supply flow rate adjustment valve 50-1 and a second supply flow rate adjustment valve 50-2. In one embodiment, transparent liquid may be supplied from both the first transparent liquid supply line 45-1 and the second transparent liquid supply line 45-2.

[0120] The switching (selection) of the line supplying the transparent liquid, the flow rate of the transparent liquid supplied from the first transparent liquid supply line 45-1 to the first inlet 44b-1, and the flow rate of the transparent liquid supplied from the second transparent liquid supply line 45-2 to the second inlet 44b-2 are determined based on parameters such as the rotation speed of the polishing table 3, the distance from the polishing surface 2a to the opposing surface 44c of the cover member 44, the type of polishing pad 2 (the material of the polishing pad 2, the shape of the recess formed on the polishing surface 2a, etc.), and the type of polishing liquid.

[0121] FIG. 20 is a schematic diagram showing yet another embodiment of the surface texture measuring system 40. The configuration of this embodiment not specifically described is the same as the embodiment described with reference to FIG. 19 , and therefore redundant description will be omitted. The surface texture measuring system 40 of this embodiment includes a first line 90A and a second line 90B instead of the first transparent liquid supply line 45-1 and the second transparent liquid supply line 45-2. The cover member 44 includes a first inlet / suction port 44e-1 and a second inlet / suction port 44e-2 instead of the first inlet 44b-1 and the second inlet / suction port 44b-2. The first inlet / suction port 44e-1 and the second inlet / suction port 44e-2 each function as the inlet and suction port described above.

[0122] The first inlet / outlet port 44e-1 is located upstream of the light transmitting portion 44a in the rotation direction of the polishing pad 2, and the second inlet / outlet port 44e-2 is located downstream of the first inlet / outlet port 44e-1 and the light transmitting portion 44a in the rotation direction of the polishing pad 2. That is, the first inlet / outlet port 44e-1 is located upstream of the optical path of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a, and the second inlet / outlet port 44e-2 is located downstream of the optical path of the light emitted from the measurement head 42 and the light reflected from the polishing surface 2a. In this embodiment, the first inlet / outlet port 44e-1 is located upstream of the measurement head 42 of the optical measurement device 41, and the second inlet / outlet port 44e-2 is located downstream of the measurement head 42 of the optical measurement device 41.

[0123] The first line 90A is connected to a first inlet / suction port 44e-1 of the cover member 44, and the second line 90B is connected to a second inlet / suction port 44e-2 of the cover member 44. The surface texture measurement system 40 includes a first selector valve 92A connected to the first line 90A and a second selector valve 92B connected to the second line 90B. The surface texture measurement system 40 further includes a first transparent liquid supply line 45-1 and a first transparent liquid suction line 55-1 connected to the first line 90A via the first selector valve 92A, and a second transparent liquid supply line 45-2 and a second transparent liquid suction line 55-2 connected to the second line 90B via the second selector valve 92B.

[0124] The first switching valve 92A is configured to switch the line communicating with the first line 90A between the first transparent liquid supply line 45-1 and the first transparent liquid suction line 55-1. Similarly, the second switching valve 92B is configured to switch the line communicating with the second line 90B between the second transparent liquid supply line 45-2 and the second transparent liquid suction line 55-2. When the first line 90A is connected to the first transparent liquid supply line 45-1, the first transparent liquid supply line 45-1 is configured to supply transparent liquid onto the polishing pad 2 through the first inlet / suction port 44e-1. When the first line 90A is connected to the first transparent liquid suction line 55-1, the first transparent liquid suction line 55-1 is configured to suck the transparent liquid flowing through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 through the first inlet / suction port 44e-1.

[0125] Similarly, when the second line 90B is in communication with the second transparent liquid supply line 45-2, the second transparent liquid supply line 45-2 is configured to supply transparent liquid onto the polishing pad 2 through the second inlet / suction port 44e-2. When the second line 90B is in communication with the second transparent liquid suction line 55-2, the second transparent liquid suction line 55-2 is configured to suck in the transparent liquid flowing through the gap between the cover member 44 and the polishing surface 2a of the polishing pad 2 through the second inlet / suction port 44e-2.

[0126] The surface texture measurement system 40 further includes a first supply flow rate control valve 50-1 that can adjust the flow rate of the transparent liquid supplied from the first transparent liquid supply line 45-1 to the first inlet / suction port 44e-1, and a first flow meter 51-1 that measures the flow rate of the transparent liquid flowing through the first transparent liquid supply line 45-1. The first supply flow rate control valve 50-1 and the first flow meter 51-1 are attached to the first transparent liquid supply line 45-1. The surface texture measurement system 40 further includes a first suction flow rate control valve 57-1 that can adjust the flow rate of the transparent liquid sucked by the first transparent liquid suction line 55-1 through the first inlet / suction port 44e-1, and a first flow meter 58-1 that measures the flow rate of the transparent liquid flowing through the first transparent liquid suction line 55-1. The first suction flow rate control valve 57-1 and the first flow meter 58-1 are attached to the first transparent liquid suction line 55-1. In one embodiment, the first switching valve 92A, the first supply flow rate adjustment valve 50-1, and the first suction flow rate adjustment valve 57-1 may be an integrated device.

[0127] Similarly, the surface texture measurement system 40 further includes a second supply flow rate control valve 50-2 that can adjust the flow rate of the transparent liquid supplied from the second transparent liquid supply line 45-2 to the second inlet / suction port 44e-2, and a second flow meter 51-2 that measures the flow rate of the transparent liquid flowing through the second transparent liquid supply line 45-2. The second supply flow rate control valve 50-2 and the second flow meter 51-2 are attached to the second transparent liquid supply line 45-2. The surface texture measurement system 40 further includes a second suction flow rate control valve 57-2 that can adjust the flow rate of the transparent liquid sucked by the second transparent liquid suction line 55-2 through the second inlet / suction port 44e-2, and a second flow meter 58-2 that measures the flow rate of the transparent liquid flowing through the second transparent liquid suction line 55-2. The second suction flow rate control valve 57-2 and the second flow meter 58-2 are attached to the second transparent liquid suction line 55-2. In one embodiment, the second switching valve 92B, the second supply flow rate adjustment valve 50-2, and the second suction flow rate adjustment valve 57-2 may be an integrated device.

[0128] The first switching valve 92A, the second switching valve 92B, the first supply flow rate adjustment valve 50-1, the first suction flow rate adjustment valve 57-1, the second supply flow rate adjustment valve 50-2, and the second suction flow rate adjustment valve 57-2 are electrically connected to the operation control unit 70, and the operations of the first switching valve 92A, the second switching valve 92B, the first supply flow rate adjustment valve 50-1, the first suction flow rate adjustment valve 57-1, the second supply flow rate adjustment valve 50-2, and the second suction flow rate adjustment valve 57-2 are controlled by the operation control unit 70. In one embodiment, the first switching valve 92A, the second switching valve 92B, the first supply flow rate adjustment valve 50-1, the first suction flow rate adjustment valve 57-1, the second supply flow rate adjustment valve 50-2, and the second suction flow rate adjustment valve 57-2 may be manual.

[0129] The surface texture measurement system 40 is configured to supply transparent liquid from at least one of a first line 90A and a second line 90B. The surface texture measurement system 40 selectively switches the line supplying the transparent liquid between the first line 90A, which is in communication with the first transparent liquid supply line 45-1, and the second line 90B, which is in communication with the second transparent liquid supply line 45-2, using a first switching valve 92A and a second switching valve 92B. In one embodiment, the transparent liquid may be supplied from both the first line 90A, which is in communication with the first transparent liquid supply line 45-1, and the second line 90B, which is in communication with the second transparent liquid supply line 45-2.

[0130] Furthermore, the surface texture measuring system 40 may use the first switching valve 92A and the second switching valve 92B to connect the first line 90A or the second line 90B, to which no transparent liquid is being supplied, to the first transparent liquid suction line 55-1 or the second transparent liquid suction line 55-2, thereby sucking the transparent liquid from above the polishing pad 2. In one embodiment, the surface texture measuring system 40 does not need to suck the transparent liquid from above the polishing pad 2.

[0131] The switching (selection) of the lines connected to the first line 90A and the second line 90B, the flow rate of the transparent liquid supplied from the first transparent liquid supply line 45-1 to the first inlet / suction port 44e-1, the flow rate of the transparent liquid supplied from the second transparent liquid supply line 45-2 to the second inlet / suction port 44e-2, the flow rate of the transparent liquid sucked by the first transparent liquid suction line 55-1 through the first inlet / suction port 44e-1, and the flow rate of the transparent liquid sucked by the second transparent liquid suction line 55-2 through the second inlet / suction port 44e-2 are determined based on parameters such as the rotation speed of the polishing table 3, the distance from the polishing surface 2a to the opposing surface 44c of the cover member 44, the type of polishing pad 2 (the material of the polishing pad 2, the shape of the recesses formed on the polishing surface 2a, etc.), and the type of polishing liquid.

[0132] 18 to 20 may further include the cover member height adjustment mechanism 53 described with reference to Fig. 9, and may be configured so that the cover member height adjustment mechanism 53 adjusts the height of the cover member 44. Moreover, the surface texture measurement system 40 shown in Fig. 18 to 20 may further include the imaging device 72 described with reference to Fig. 14, and may be configured so that the operation control unit 70 controls the operation of the supply flow rate adjustment valve 50, the first supply flow rate adjustment valve 50-1, the second supply flow rate adjustment valve 50-2, the suction flow rate adjustment valve 57, the first suction flow rate adjustment valve 57-1, and / or the second suction flow rate adjustment valve 57-2 based on an image of the monitoring region MR (see Fig. 14).

[0133] FIG. 21 is a schematic diagram showing yet another embodiment of the surface texture measuring system 40. The configuration of this embodiment, unless otherwise specified, is the same as the embodiment described with reference to FIG. 9 , and therefore redundant description will be omitted. The surface texture measuring system 40 of this embodiment further includes a first prism 84, a second prism 85, and a light-shielding member 86. The optical measurement device 41 of this embodiment includes a first measuring head 81 having a light source 81a, a second measuring head 82 having a light-receiving unit 82a, and a data processing unit 43 connected to the second measuring head 82. The cover member 44 of this embodiment includes a first cover member 88 and a second cover member 89.

[0134] The first cover member 88 has an opposing surface 88b that is parallel to the polishing surface 2a of the polishing pad 2. The first cover member 88 has a light-transmitting portion 88a on the optical path of the light irradiated by the first measuring head 81. The light-transmitting portion 88a is a portion indicated by a dashed line in FIG. 21 through which the light irradiated by the first measuring head 81 passes. The light-transmitting portion 88a is made of a transparent material that transmits the light irradiated by the first measuring head 81. In this embodiment, the first cover member 88 is a transparent plate, and the entire first cover member 88, including the light-transmitting portion 88a, is made of a transparent material.

[0135] The second cover member 89 has an opposing surface 89c that is parallel to the polishing surface 2a of the polishing pad 2. The second cover member 89 has a light-transmitting portion 89a on the optical path of light reflected from the polishing surface 2a. The light-transmitting portion 89a is the portion indicated by the dashed line in FIG. 21 through which the light reflected from the polishing surface 2a passes. The light-transmitting portion 89a is made of a transparent material that transmits the light reflected from the polishing surface 2a. In this embodiment, the second cover member 89 is a transparent plate, and the entire second cover member 89, including the light-transmitting portion 89a, is made of a transparent material.

[0136] The second cover member 89 has a light transmitting portion 88a of the first cover member 88 and an injection port 89b located upstream of the light transmitting portion 89a of the second cover member 89 in the rotation direction of the polishing pad 2. In other words, the injection port 89b is located upstream of the optical path of the light emitted from the first measurement head 81 and the optical path of the light reflected from the polishing surface 2a. In this embodiment, the first cover member 88 and the second cover member 89 have the same thickness, and the opposing surface 88b of the first cover member 88 and the opposing surface 89c of the second cover member 89 are in the same plane.

[0137] The transparent liquid supply line 45 is connected to an inlet 89b of the second cover member 89, and is configured to supply transparent liquid onto the polishing pad 2 through the inlet 89b. As shown in Fig. 21, the entire cover member 44 (i.e., the first cover member 88 and the second cover member 89) is spaced apart from the polishing surface 2a of the polishing pad 2. The gap between the opposing surfaces of the cover members 44 (i.e., the opposing surfaces 88b of the first cover member 88 and the opposing surfaces 89c of the second cover member 89) and the polishing surface 2a of the polishing pad 2 is filled with a flow of transparent liquid.

[0138] The first prism 84 and the second prism 85 are disposed between the optical measurement device 41 and the cover member 44. More specifically, the first prism 84 is disposed between the first measurement head 81 and the first cover member 88, and the second prism 85 is disposed between the second measurement head 82 and the second cover member 89. The first prism 84 and the first cover member 88 are bonded together with a transparent adhesive or the like that allows light to pass through, and the second prism 85 and the second cover member 89 are also bonded together with a transparent adhesive or the like that allows light to pass through.

[0139] The light source 81a of the first measuring head 81 irradiates light (laser light) onto the polishing surface 2a of the polishing pad 2 through a first prism 84, and the light receiving unit 82a of the second measuring head 82 receives the light reflected from the polishing surface 2a through a second prism 85. The data processing unit 43 measures the surface texture of the polishing pad 2 by processing the measured values ​​based on the reflected light sent from the second measuring head 82. The measurement results of the surface texture of the polishing pad 2 are sent to the operation control unit 70. In one embodiment, the first measuring head 81 and the second measuring head 82 may have the same configuration as the first measuring head 75 and the second measuring head 76 described with reference to FIG. 15 , or may have the same configuration as the first measuring head 77 and the second measuring head 78 described with reference to FIG. 16 , or may have the same configuration as the pad imaging device 73 described with reference to FIG. 17 . The optical measuring device 41 of this embodiment can accurately measure the surface properties of the polishing pad 2 by irradiating light onto the polishing surface 2a at a low angle and reflecting the light from the polishing surface 2a at a low angle.

[0140] In order to irradiate light onto the polishing surface 2a at a low angle and reflect the light from the polishing surface 2a at a low angle, the first measurement head 81 and the second measurement head 82 must be positioned far away from the measurement point on the polishing surface 2a, which increases the overall size of the optical measurement device 41. Therefore, the surface texture measurement system 40 of this embodiment includes a first prism 84 and a second prism 85 that deflect the optical path. The first prism 84 is configured to pass light irradiated from the optical measurement device 41 and deflect the optical path of the light. More specifically, the first prism 84 is configured to deflect light emitted from the light source 81a of the first measurement head 81.

[0141] The second prism 85 is configured to pass light reflected from the polished surface 2a and deflect the optical path of the reflected light. More specifically, the first prism 84 is configured to deflect the light reflected from the polished surface 2a. With this configuration, the entire optical measurement device 41 can be made compact when light is irradiated onto the polished surface 2a at a low angle and reflected from the polished surface 2a at a low angle.

[0142] The light-shielding member 86 is disposed between the first prism 84 and the second prism 85 and configured to block light between the first prism 84 and the second prism 85. Furthermore, the light-shielding member 86 is disposed between the first cover member 88 and the second cover member 89 and configured to block light between the first cover member 88 and the second cover member 89. In this embodiment, the light-shielding member 86 is configured as a black light-shielding plate. An upper portion of the light-shielding member 86 protrudes upward from the apexes of the first prism 84 and the second prism 85, and a lower end of the light-shielding member 86 is in the same plane as the opposing surface 88b of the first cover member 88 and the opposing surface 89c of the second cover member 89. Therefore, the light-shielding member 86 extends at least from the apexes of the first prism 84 and the second prism 85 to the opposing surface 88b of the first cover member 88 and the opposing surface 89c of the second cover member 89.

[0143] In one embodiment, the light-blocking member 86 may be made of a black filler (e.g., silicone rubber) that fills the gap between the first prism 84 and the second prism 85 and the gap between the first cover member 88 and the second cover member 89. The light-blocking member 86 and the first cover member 88 are in close contact with each other so that no gap is formed between them. Similarly, the light-blocking member 86 and the second cover member 89 are in close contact with each other so that no gap is formed between them. The configuration of the light-blocking member 86 is not limited to the present embodiment as long as it has light-blocking properties between the first prism 84 and the second prism 85 and between the first cover member 88 and the second cover member 89 and seals the gap between the first cover member 88 and the second cover member 89.

[0144] The light-shielding member 86 blocks light between the first prism 84 and the second prism 85, thereby preventing light that has passed through the first prism 84 from passing through the second prism 85 without reaching the polishing surface 2 a. Similarly, the light-shielding member 86 blocks light between the first cover member 88 and the second cover member 89, thereby preventing light that has passed through the first cover member 88 from passing through the second cover member 89 without reaching the polishing surface 2 a. In other words, the light-shielding member 86 can prevent light from shortcutting between the first prism 84 and the second prism 85, and also prevent light from shortcutting between the first cover member 88 and the second cover member 89.

[0145] In this embodiment, the first measuring head 81 is located downstream of the second measuring head 82 in the rotation direction of the polishing pad 2, the first prism 84 is located downstream of the second prism 85 in the rotation direction of the polishing pad 2, and the first cover member 88 is located downstream of the second cover member 89 in the rotation direction of the polishing pad 2. In one embodiment, the first measuring head 81 may be located upstream of the second measuring head 82 in the rotation direction of the polishing pad 2, the first prism 84 may be located upstream of the second prism 85 in the rotation direction of the polishing pad 2, and the first cover member 88 may be located upstream of the second cover member 89 in the rotation direction of the polishing pad 2. In this case, instead of the injection port 89b of the second cover member 89 described above, the first cover member 88 has a light transmitting portion 88a of the first cover member 88 and an injection port located upstream of the light transmitting portion 89a of the second cover member 89 in the rotation direction of the polishing pad 2. The transparent liquid supply line 45 is connected to the inlet of this first cover member 88 and is configured to supply the transparent liquid onto the polishing pad 2 through the inlet.

[0146] Figure 22 is a schematic diagram showing yet another embodiment of the surface texture measurement system 40. The configuration of this embodiment, which is not particularly described, is the same as the embodiment described with reference to Figure 21, and therefore a duplicated description thereof will be omitted. In this embodiment, the first cover member 88 has a suction port 88c, and the surface texture measurement system 40 further includes a transparent liquid suction line 55 connected to the suction port 88c. The configuration of the suction port 88c, which is not particularly described, is the same as the configuration of the suction port 44d in the embodiment described with reference to Figure 12, and therefore a duplicated description thereof will be omitted.

[0147] The suction port 88c is located downstream of the injection port 89b of the second cover member 89, the light transmitting portion 89a, and the light transmitting portion 88a of the first cover member 89 in the rotation direction of the polishing pad 2. In other words, the suction port 88c is located downstream of the optical path of the light emitted from the first measurement head 81 and the optical path of the light reflected from the polishing surface 2a. The transparent liquid suction line 55 is configured to suck the transparent liquid flowing through the gap between the cover member 44 (i.e., the first cover member 88 and the second cover member 89) and the polishing surface 2a of the polishing pad 2 through the suction port 88c.

[0148] According to this embodiment, a flow of transparent liquid from the inlet 89b toward the suction port 88c is formed in the gap between the cover member 44 (i.e., the first cover member 88 and the second cover member 89) and the polishing surface 2a of the polishing pad 2, so that the optical path can be filled with transparent liquid when measuring the surface texture of the polishing pad 2. Furthermore, by sucking the transparent liquid on the polishing pad 2 through the transparent liquid suction line 55, it is possible to prevent the transparent liquid from leaking out of the cover member 44 (i.e., the first cover member 88 and the second cover member 89). Therefore, when measuring the surface texture of the polishing pad 2 while the substrate W is being polished with the polishing liquid, it is possible to prevent the polishing liquid from being diluted with the transparent liquid. Furthermore, by measuring the surface texture of the polishing pad 2 while the substrate W is being polished with the polishing liquid, it is possible to measure the surface texture of the polishing pad 2 in a state where the substrate W is actually being polished using the polishing liquid.

[0149] In this embodiment, the first measuring head 81 is located downstream of the second measuring head 82 in the rotation direction of the polishing pad 2, the first prism 84 is located downstream of the second prism 85 in the rotation direction of the polishing pad 2, and the first cover member 88 is located downstream of the second cover member 89 in the rotation direction of the polishing pad 2.

[0150] In one embodiment, the first measuring head 81 may be located upstream of the second measuring head 82 in the rotation direction of the polishing pad 2, the first prism 84 may be located upstream of the second prism 85 in the rotation direction of the polishing pad 2, and the first cover member 88 may be located upstream of the second cover member 89 in the rotation direction of the polishing pad 2. In this case, instead of the injection port 89b of the second cover member 89 described above, the first cover member 88 has a light transmitting portion 88a of the first cover member 88 and an injection port located upstream of the light transmitting portion 89a of the second cover member 89 in the rotation direction of the polishing pad 2. The transparent liquid supply line 45 is connected to the injection port of the first cover member 88 and is configured to supply the transparent liquid onto the polishing pad 2 through the injection port. Furthermore, instead of the suction port 88c of the first cover member 88 described above, the second cover member 89 has an injection port of the first cover member 88, a light transmitting portion 89a, and a suction port located downstream of the light transmitting portion 89a of the second cover member 89 in the rotation direction of the polishing pad 2. The transparent liquid suction line 55 is connected to the suction port of the second cover member 89 and is configured to suck the transparent liquid flowing through the gap between the cover member 44 (i.e., the first cover member 88 and the second cover member 89) and the polishing surface 2a of the polishing pad 2 through the suction port.

[0151] 21 and 22 may further include the cover member height adjustment mechanism 53 described with reference to FIG. 9, and the cover member height adjustment mechanism 53 may be configured to adjust the height of the cover member 44 (i.e., the first cover member 88 and the second cover member 89). In this case, the cover member height adjustment mechanism 53 is configured to adjust the heights of the cover member 44, the first prism 84, the second prism 85, and the light-shielding member 86 all together. The surface texture measurement system 40 shown in FIGS. 21 and 22 may also further include the imaging device 72 described with reference to FIG. 14, and may be configured so that the operation control unit 70 controls the operation of the supply flow rate adjustment valve 50 and / or the suction flow rate adjustment valve 57 based on an image of the monitoring region MR (see FIG. 14).

[0152] The embodiment shown in FIG. 22 may be combined with the embodiments described with reference to FIGS.

[0153] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may 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 in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0154] 1 polishing head 2 polishing pads 3 Polishing table 5 Polishing liquid supply nozzle 6 Table Motor 10 Grinding head shaft 14 Polishing head swing shaft 16 Polishing head swing arm 20 Dresser 22 Dressing disc 24 Dresser shaft 25 Support Blocks 29 Dresser swing arm 30 Dresser swing shaft 32 Pad height measuring device 40 Surface Texture Measurement System 41 Optical measuring device 42 Measuring head 43 Data Processing Unit 44 Cover member 45 Transparent liquid supply line 45-1 First transparent liquid supply line 45-2 Second transparent liquid supply line 47 Measuring head movement mechanism 48 Measuring head arm 49 Actuators 50 Supply flow control valve 50-1 First supply flow control valve 50-2 Second supply flow control valve 51 Flow meter 51-1 1st flow meter 51-2 2nd flow meter 53 Cover member height adjustment mechanism 55 Transparent liquid suction line 55-1 First transparent liquid suction line 55-2 Second transparent liquid suction line 57 Suction flow control valve 57-1 First suction flow control valve 57-2 Second suction flow control valve 58 Flow meter 58-1 1st flow meter 58-2 2nd flow meter 60 Polishing control unit 70 Motion control section 72 Imaging device 73 Pad Imaging Device 74 Lighting equipment 75, 77, 81 First measuring head 76, 78, 82 Second measuring head 84 First Prism 85 Second Prism 86 Light blocking material 88 First cover member 89 Second cover member 90A 1st Line 90B 2nd line 92A, 92B Switching valve

Claims

1. an optical measuring device that irradiates a polishing surface of a rotating polishing pad with light and measures the surface properties of the polishing pad based on the light reflected from the polishing surface; a cover member disposed between the optical measurement device and the polishing pad; a transparent liquid supply line connected to an inlet provided in the cover member and supplying a transparent liquid onto the polishing pad through the inlet; The cover member has a light-transmitting portion on the optical paths of the light and the reflected light.

2. 2. The surface texture measuring system according to claim 1, wherein the injection port is located upstream of the light transmitting portion in the rotation direction of the polishing pad.

3. 2. The surface texture measuring system according to claim 1, wherein the injection port is located downstream of the light transmitting portion in the rotation direction of the polishing pad.

4. The surface texture measuring system according to claim 1 , further comprising a supply flow rate adjustment valve that adjusts the flow rate of the transparent liquid supplied from the transparent liquid supply line.

5. 2. The surface texture measuring system according to claim 1, further comprising a transparent liquid suction line connected to a suction port provided in the cover member, for sucking the transparent liquid on the polishing pad through the suction port.

6. 6. The surface texture measuring system according to claim 5, further comprising a suction flow rate adjustment valve that adjusts the flow rate of the transparent liquid sucked by the transparent liquid suction line.

7. The surface texture measuring system according to claim 1 , wherein the cover member has an opposing surface parallel to the polishing surface of the polishing pad.

8. 8. The surface texture measuring system according to claim 7, wherein the distance from the polishing surface of the polishing pad to the opposing surface is 5 mm or less.

9. The surface texture measuring system according to claim 1 , further comprising a cover member height adjustment mechanism for adjusting the height of the cover member relative to the polishing surface.

10. The surface texture measuring system according to claim 1 , further comprising an imaging device that generates an image of a monitoring area including a measurement point on the polished surface onto which the light is irradiated and from which the light is reflected.

11. a supply flow rate control valve capable of adjusting the flow rate of the transparent liquid supplied from the transparent liquid supply line; Further comprising an operation control unit, The surface texture measuring system according to claim 10 , wherein the operation control unit is configured to control the operation of the supply flow rate adjustment valve based on the image of the monitoring area.

12. a transparent liquid suction line connected to a suction port provided in the cover member and configured to suck the transparent liquid on the polishing pad through the suction port; a suction flow rate adjustment valve that adjusts the flow rate of the transparent liquid suctioned from the transparent liquid supply line; The surface texture measuring system according to claim 11 , wherein the operation control unit is configured to control the operation of the suction flow rate adjustment valve based on the image of the monitoring area.

13. 13. The surface texture measuring system according to claim 12, wherein the operation control unit is configured to issue an alarm when an abnormality in the flow of the transparent liquid on the polishing pad is detected based on the image of the monitoring area.

14. a first prism disposed between the optical measurement device and the cover member, the first prism passing the light emitted from the optical measurement device and deflecting an optical path of the light; a second prism disposed between the optical measurement device and the cover member, the second prism passing the reflected light from the polished surface and deflecting the optical path of the reflected light; a light blocking member disposed between the first prism and the second prism, for blocking light between the first prism and the second prism; the cover member includes a first cover member that passes the light irradiated from the optical measurement device and a second cover member that passes the light reflected from the polishing surface; 2. The surface texture measurement system according to claim 1, wherein the light-shielding member is disposed between the first cover member and the second cover member and configured to block light between the first cover member and the second cover member.

15. a surface texture measurement system according to any one of claims 1 to 14; a polishing table that supports the polishing pad; a table motor that rotates the polishing table together with the polishing pad; A polishing apparatus comprising a polishing head that presses a substrate against the polishing surface of the polishing pad to polish the substrate.

16. With the polishing pad supported by a polishing table, the polishing table is rotated together with the polishing pad; supplying a transparent liquid onto the polishing pad through an inlet provided in a cover member having a light-transmitting portion, the cover member being disposed between an optical measurement device and the polishing pad; A surface texture measuring method comprising: using the optical measuring device to irradiate light onto the polishing surface of the polishing pad through the light transmitting portion; receiving reflected light from the polishing surface through the light transmitting portion; and measuring the surface texture of the polishing pad based on the reflected light.

17. 17. The surface texture measuring method according to claim 16, wherein the injection port is located upstream of the light transmitting portion in the rotation direction of the polishing pad.

18. 17. The surface texture measuring method according to claim 16, wherein the injection port is located downstream of the light transmitting portion in the rotation direction of the polishing pad.

19. The surface texture measuring method according to claim 16, further comprising adjusting a flow rate of the transparent liquid supplied onto the polishing pad.

20. 17. The surface texture measuring method according to claim 16, further comprising: sucking the transparent liquid on the polishing pad through a suction port provided in the cover member while supplying the transparent liquid onto the polishing pad through the injection port.

21. The surface texture measuring method according to claim 20, further comprising adjusting a flow rate of the transparent liquid sucked from above the polishing pad.

22. The surface texture measuring method according to claim 16 , wherein the cover member has an opposing surface parallel to the polishing surface of the polishing pad.

23. 23. The surface texture measuring method according to claim 22, wherein the distance from the polishing surface of the polishing pad to the opposing surface is 5 mm or less.

24. The surface texture measuring method according to claim 16, further comprising adjusting the height of the cover member relative to the polished surface.

25. The surface texture measuring method according to claim 16, further comprising generating, by an imaging device, an image of a monitoring area including the measurement point on the polished surface where the light is irradiated and reflected.

26. 26. The surface texture measuring method of claim 25, further comprising adjusting a flow rate of the transparent liquid supplied onto the polishing pad based on the image of the monitoring area.

27. While supplying the transparent liquid onto the polishing pad through the inlet, the transparent liquid on the polishing pad is sucked through the suction port provided in the cover member; 27. The surface texture measuring method according to claim 26, further comprising adjusting a flow rate of the transparent liquid sucked from above the polishing pad based on the image of the monitoring area.

28. 27. The surface texture measuring method according to claim 26, further comprising issuing an alarm when an abnormality in the flow of the transparent liquid on the polishing pad is detected based on the image of the monitoring area.

29. Polishing the substrate with a polishing pad; A polishing method, comprising: measuring the surface texture of the polishing pad by the surface texture measuring method according to any one of claims 16 to 28; and determining whether or not it is time to replace the polishing pad based on the measurement results of the surface texture.

30. A new polishing pad is supported on the polishing table. polishing a substrate for a breaking-in treatment to break in the new polishing pad; measuring the surface texture of the new polishing pad by the surface texture measuring method according to any one of claims 16 to 28; a polishing method comprising: determining whether the break-in process is complete based on the measurement results of the surface texture; and, when it is determined that the break-in process is complete, polishing the substrate using the new polishing pad.

Images