Substrate polishing apparatus and substrate polishing method

Abstract

To provide a substrate polishing device which can measure film thickness of a substrate during polishing with high accuracy without lowering light transmittance.SOLUTION: A substrate polishing device 1 includes a stage 10, a polishing head 21 for holding a polishing pad 22, a polishing liquid supply nozzle 28, a film thickness measurement head 31, a spectral analysis part 34, and a head nozzle 40 mounted with the film thickness measurement head 31, wherein the head nozzle 40 includes a first flow channel system 71 and a second flow channel system 72 for forming a flow of a liquid crossing an optical path of light and reflected light; the first flow channel system 71 has an opening 154 positioned on the optical path; the second flow channel system 72 has a liquid discharge port 254 and a liquid suction port 255; and the liquid discharge port 254 and the liquid suction port 255 are positioned on both sides of the opening 154.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a substrate polishing apparatus and a substrate polishing method, and particularly to a substrate polishing apparatus and a substrate polishing method for measuring the film thickness of a substrate during polishing.

Background Art

[0002] Chemical Mechanical Polishing (CMP) is a technique in which a polishing liquid containing abrasive grains such as silica (SiO2) is supplied onto the polishing surface of a polishing pad, and the substrate to be polished is brought into sliding contact with the polishing surface while rotating a polishing pad having a smaller diameter than the substrate to perform polishing. Substrate polishing apparatuses used in the CMP process include a method in which the polished surface of the substrate faces upward (face-up type) and a method in which the polished surface of the substrate faces downward (face-down type).

[0003] The face-up type substrate polishing apparatus is configured to polish the substrate by placing the polished surface of the substrate upward on a stage, bringing the polishing pad into contact with the substrate while rotating a polishing pad having a smaller diameter than the substrate, and oscillating the polishing pad. Polishing of the substrate is terminated when the film thickness of the substrate reaches a predetermined target value. As a method for measuring the film thickness of the substrate during polishing, there is a method of irradiating light onto the surface of the substrate by an optical film thickness measuring device provided in the substrate polishing apparatus and determining the film thickness based on the spectral waveform of the light reflected from the substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since foreign substances such as polishing liquid and polishing debris exist on the surface of the substrate during polishing, when light is irradiated by a film thickness measuring device and the reflected light is received, the light transmittance decreases. Therefore, it has been difficult to measure the film thickness of the substrate during polishing with high accuracy.

[0006] Therefore, the present invention provides a substrate polishing apparatus capable of measuring the film thickness with high accuracy without reducing the light transmittance when measuring the film thickness of a substrate during polishing.

Means for Solving the Problems

[0007] In one aspect, a stage that supports the surface to be polished of the substrate upward and rotates the substrate, a polishing head that holds a polishing pad having a polishing surface for polishing the substrate supported by the stage, a polishing liquid supply nozzle that supplies polishing liquid onto the surface of the substrate, a film thickness measurement head that irradiates light onto a measurement region on the surface of the substrate on the stage and receives the reflected light from the measurement region, a spectrum analysis unit that generates a spectrum of the reflected light and determines the film thickness of the substrate from the spectrum, and a head nozzle to which the film thickness measurement head is attached are provided. The head nozzle includes a first flow path system and a second flow path system that form a flow of liquid across the optical paths of the light and the reflected light. The first flow path system has an opening located on the optical path, and the second flow path system has a liquid discharge port and a liquid suction port. The liquid discharge port and the liquid suction port are located on both sides of the opening. A substrate polishing apparatus is provided.

[0008] In one aspect, the liquid discharge port and the liquid suction port are arranged symmetrically with respect to the opening. In one aspect, the opening, the liquid discharge port, and the liquid suction port are located within the bottom surface of the head nozzle. In one aspect, the liquid discharge port is located upstream of the opening and the liquid suction port in the rotational direction of the substrate.

[0009] In one aspect, the first flow path system includes a fluid chamber provided on the optical path, a first liquid supply flow path for supplying liquid to the fluid chamber, a first liquid discharge flow path for discharging liquid from the fluid chamber, and has the opening communicating with the lower end of the fluid chamber and capable of approaching the surface of the substrate. The second flow path system includes a second liquid supply flow path for supplying liquid onto the surface of the substrate, a second liquid discharge flow path for discharging liquid on the surface of the substrate, a liquid discharge port communicating with the second liquid supply flow path and capable of approaching the surface of the substrate, and a liquid suction port communicating with the second liquid discharge flow path and capable of approaching the surface of the substrate.

[0010] In one aspect, both the liquid discharge port and the liquid suction port are larger than the opening. In one aspect, the liquid suction port is larger than the liquid discharge port. In one aspect, the second flow path system further includes a liquid collection groove connected to the liquid suction port and capable of approaching the surface of the substrate. The liquid collection groove is located upstream of the liquid suction port in the rotation direction of the substrate, and the width of the liquid collection groove is larger than the width of the liquid suction port.

[0011] There is provided a substrate polishing method including the steps of supporting the substrate with the polished surface facing upward and rotating the substrate, pressing a polishing pad having a polishing surface against the substrate by a polishing head while supplying polishing liquid to the surface of the substrate to polish the substrate, flowing liquid through an opening provided in a head nozzle close to the surface of the substrate, supplying liquid onto the surface of the substrate from a liquid discharge port provided in the head nozzle, sucking the liquid on the surface of the substrate through a liquid suction port, irradiating light from a film thickness measurement head through the opening onto a measurement area on the surface of the substrate, receiving reflected light from the measurement area through the opening by the film thickness measurement head, and determining the film thickness of the substrate from the spectrum of the reflected light. The liquid discharge port and the liquid suction port are located on both sides of the opening.

[0012] In one aspect, the step of flowing the liquid into the opening provided in the head nozzle is a step of flowing the liquid into the fluid chamber and the opening provided in the head nozzle. The step of irradiating light from the film thickness measurement head through the opening onto the measurement region on the surface of the substrate is a step of irradiating light from the film thickness measurement head through the fluid chamber and the opening onto the measurement region on the surface of the substrate. The step of receiving, by the film thickness measurement head, the reflected light from the measurement region through the opening is a step of receiving, by the film thickness measurement head, the reflected light from the measurement region through the opening and the fluid chamber.

[0013] In one aspect, the liquid discharge port and the liquid suction port are symmetrically arranged with respect to the opening. In one aspect, the opening, the liquid discharge port, and the liquid suction port are located within the bottom surface of the head nozzle. In one aspect, the liquid discharge port is located upstream of the opening and the liquid suction port in the rotational direction of the substrate.

[0014] In one aspect, both the liquid discharge port and the liquid suction port are larger than the opening. In one aspect, the liquid suction port is larger than the liquid discharge port. In one aspect, the head nozzle has a liquid collection groove connected to the liquid suction port. The liquid collection groove is located upstream of the liquid suction port in the rotational direction of the substrate, and the width of the liquid collection groove is larger than the width of the liquid suction port.

Advantages of the Invention

[0015] According to the present invention, the head nozzle includes a first flow path system and a second flow path system, and the polishing liquid and polishing debris present on the optical path are removed by these two separate liquid supply and discharge mechanisms. Since the optical path is filled with a transparent liquid during film thickness measurement, the film thickness of the substrate being polished can be measured with high accuracy.

[0016] The liquid supplied onto the surface of the substrate from the liquid discharge port of the second flow path system flows along the surface of the substrate through the gap between the opening of the first flow path system and the substrate, and is sucked from the liquid suction port of the second flow path system. Due to this liquid flow, the polishing liquid and polishing debris existing between the opening and the substrate are removed, so that the film thickness of the substrate being polished can be measured with high accuracy.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding components are denoted by the same reference numerals, and redundant descriptions are omitted. FIG. 1 is a top view showing an embodiment of a substrate polishing apparatus 1. FIG. 2 is a side view of the substrate polishing apparatus 1 shown in FIG. 1 as viewed from the direction indicated by arrow A. As shown in FIGS. 1 and 2, the substrate polishing apparatus 1 includes a stage 10 that supports a substrate W, a polishing unit 20 for polishing the substrate W, and a film thickness measuring device 30 for measuring the film thickness of the substrate W. Examples of the substrate W include wafers used in the manufacture of semiconductor devices. In the embodiments described below, the substrate W is circular, but may have a rectangular shape.

[0019] The stage 10 supports the substrate W to be polished with its polished surface 2 facing upward. The stage 10 has a plurality of through holes (not shown), and the substrate W is supported by vacuum suction through the plurality of holes. The stage 10 is connected to a stage rotation mechanism such as a motor (not shown), and the stage rotation mechanism is configured to rotate the stage 10 and the substrate W.

[0020] The polishing unit 20 includes a polishing head 21, a polishing head arm 23, a polishing head moving mechanism 24, a rotating shaft 25, a polishing head rotating mechanism 26, and a polishing liquid supply nozzle 28. The polishing head 21 holds a polishing pad 22 having a polishing surface 22a, and is connected to the polishing head arm 23 via a rotating shaft 25 extending in the height direction. The rotating shaft 25 is connected to a polishing head rotating mechanism 26 including a motor or the like, and the polishing head rotating mechanism 26 is configured to rotate the polishing head 21 and the polishing pad 22 together with the rotating shaft 25 about the rotating shaft 25.

[0021] The polishing head arm 23 is further connected to a polishing head moving mechanism 24, and the polishing head moving mechanism 24 swings the polishing head arm 23 in the direction indicated by the arrow to move the polishing head 21 between a polishing position and a non-polishing position. The polishing position is a position where the polishing head 21 can polish the substrate W, that is, a position where at least a part of the polishing head 21 is disposed above the substrate W on the stage 10. The non-polishing position is a position where the polishing head 21 cannot polish the substrate W, that is, a position where the entire polishing head 21 is disposed outside the substrate W on the stage 10. In FIGS. 1 and 2, the polishing head 21 is disposed at the non-polishing position.

[0022] Two polishing liquid supply nozzles 28 are connected to the polishing head arm 23, and the tips of the respective polishing liquid supply nozzles 28 are disposed on both sides in the moving direction of the polishing head 21 with the polishing head 21 interposed therebetween. The two polishing liquid supply nozzles 28 are configured to supply a polishing liquid containing abrasive grains such as silica (SiO2) or cleaning water onto the surface of the substrate W.

[0023] The operations of the stage rotation mechanism and the polishing unit 20 are controlled by an operation control unit 60. The operation control unit 60 is electrically connected to the stage rotation mechanism, the polishing head moving mechanism 24, and the polishing head rotation mechanism 26. The operations of the stage rotation mechanism, the polishing head moving mechanism 24, and the polishing head rotation mechanism 26 are controlled by the operation control unit 60.

[0024] The operation control unit 60 is composed of at least one computer. The operation control unit 60 includes a storage device 60a storing a program for operating the substrate polishing apparatus 1 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) and 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 operation control unit 60 is not limited to these examples.

[0025] The substrate W is polished as follows. While rotating the stage 10 and the substrate W, the operation control unit 60 supplies polishing liquid from the polishing liquid supply nozzle 28. The operation control unit 60 issues a command to the polishing head moving mechanism 24 to swing the polishing head 21 above the substrate W supported by the stage 10. The polishing pad 22 held by the polishing head 21 is rotated by the polishing head rotation mechanism 26, and the polishing head 21 presses the polishing surface 22a of the polishing pad 22 against the surface 2 to be polished of the substrate W with the polishing liquid present on the substrate W. The surface 2 to be polished 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 22.

[0026] The film thickness measuring device 30 is an optical film thickness measuring device, and includes a light source 32, a spectroscope 33, a spectrum analysis unit 34, a film thickness measuring head 31, a head nozzle 40, a film thickness measuring head arm 36, and a film thickness measuring head moving mechanism 37. The film thickness measuring head 31 has the tips of a light projecting optical fiber cable 38 and a light receiving optical fiber cable 39. The light source 32 that emits light is connected to the light projecting optical fiber cable 38. The spectroscope 33 is connected to the light receiving optical fiber cable 39. The light source 32 and the spectroscope 33 are connected to the spectrum analysis unit 34.

[0027] One end of the film thickness measurement head arm 36 is connected to the film thickness measurement head 31, and the other end of the film thickness measurement head arm 36 is connected to the film thickness measurement head movement mechanism 37. The film thickness measurement head movement mechanism 37 swings the film thickness measurement head arm 36 in the direction indicated by the arrow to move the film thickness measurement head 31 between the measurement position and the non-measurement position. The measurement position is the position where the film thickness measurement head 31 can measure the film thickness of the substrate W, that is, the position where the film thickness measurement head 31 is disposed above the substrate W on the stage 10. The non-measurement position is the position where the film thickness measurement head 31 cannot measure the film thickness of the substrate W, that is, the position where the film thickness measurement head 31 is disposed outside the substrate W on the stage 10. In FIGS. 1 and 2, the film thickness measurement head 31 is disposed at the measurement position. The film thickness measurement head movement mechanism 37 is electrically connected to the operation control unit 60, and the operation of the film thickness measurement head movement mechanism 37 is controlled by the operation control unit 60.

[0028] The film thickness measurement head 31 including the tip of the light projection optical fiber cable 38 and the tip of the light reception optical fiber cable 39 is attached to the head nozzle 40. The head nozzle 40 includes a first flow path system 71 and a second flow path system 72, which will be described in detail later. The first flow path system 71 is connected to a first liquid supply line 142 for supplying liquid to the head nozzle 40 and a first liquid discharge line 143 for discharging liquid from the head nozzle 40. The second flow path system 72 is connected to a second liquid supply line 242 for supplying liquid to the head nozzle 40 and a second liquid discharge line 243 for discharging liquid from the head nozzle 40. The first liquid supply line 142 and the second liquid supply line 242 are each connected to a liquid supply source (not shown). The liquid supplied to the head nozzle 40 is, for example, pure water. The liquid may be a transparent liquid, and may be, for example, a KOH solution used for a polishing liquid.

[0029] A first supply valve 144 and a flow meter 146 are attached to the first liquid supply line 142, and a second supply valve 244 and a flow meter 246 are attached to the second liquid supply line 242. A first discharge valve 145, a flow meter 147, and a liquid pump 148 such as an ejector are attached to the first liquid discharge line 143. A second discharge valve 245, a flow meter 247, and a liquid pump 248 such as an ejector are attached to the second liquid discharge line 243. The first supply valve 144, the second supply valve 244, the first discharge valve 145, and the second discharge valve 245 may be manual, or the first supply valve 144, the second supply valve 244, the first discharge valve 145, and the second discharge valve 245 are connected to the operation control unit 60, and the operations of the first supply valve 144, the second supply valve 244, the first discharge valve 145, and the second discharge valve 245 may be controlled by the operation control unit 60. Details of the head nozzle 40 will be described later.

[0030] FIG. 3 is a schematic diagram for explaining the principle of the optical film thickness measuring apparatus 30. In the example shown in FIG. 3, the substrate W has a lower layer and a layer to be polished formed thereon. The layer to be polished is, for example, a silicon layer or an insulating film. The film thickness measuring head 31 has the tips of a light projecting optical fiber cable 38 and a light receiving optical fiber cable 39, and is disposed to face the surface of the substrate W. In the present embodiment, the head nozzle 40 is attached to the film thickness measuring head 31, but in FIG. 3, the configuration of the head nozzle 40 is omitted for simplicity of explanation.

[0031] The light emitted from the light source 32 is transmitted to the film thickness measuring head 31 through the light projecting optical fiber cable 38, and is irradiated onto the surface of the substrate W from the film thickness measuring head 31 including the tip of the light projecting optical fiber cable 38. The light is reflected by the substrate W, and the reflected light from the substrate W is received by the film thickness measuring head 31 including the tip of the light receiving optical fiber cable 39, and is sent to the spectroscope 33 through the light receiving optical fiber cable 39. The spectroscope 33 decomposes the reflected light according to the wavelength and measures the intensity of the reflected light at each wavelength. The intensity measurement data of the reflected light is sent to the spectral analysis unit 34.

[0032] The spectral analysis unit 34 is configured to generate a spectrum of the reflected light from the intensity measurement data of the reflected light. The spectrum of the reflected light is represented as a line graph (i.e., a spectral waveform) showing the relationship between the wavelength and intensity of the reflected light. The intensity of the reflected light can also be represented as a relative value such as reflectance or relative reflectance.

[0033] The light irradiated on the substrate W is reflected at the interfaces between the medium (water in the example of FIG. 3) and the layer to be polished, and between the layer to be polished and the underlying layer, and the waves of the light reflected at these interfaces interfere with each other. The way in which these light waves interfere changes according to the thickness (i.e., optical path length) of the layer to be polished. Therefore, the spectrum generated from the reflected light from the substrate W changes according to the thickness of the layer to be polished. The spectral analysis unit 34 determines the film thickness of the substrate W based on the optical information included in the spectrum of the reflected light.

[0034] FIG. 4 is a diagram showing an example of a spectrum generated by the spectral analysis unit 34. In FIG. 4, the horizontal axis represents the wavelength of the reflected light from the substrate W, and the vertical axis represents the relative reflectance derived from the intensity of the reflected light. The relative reflectance is an index indicating the intensity of the reflected light and is the ratio of the intensity of the light to a predetermined reference intensity. By dividing the intensity of the light (measured intensity) at each wavelength by the predetermined reference intensity, unnecessary noise such as variations in the intensity inherent to the optical system and light source of the apparatus can be removed from the measured intensity. In the example shown in FIG. 4, the spectrum of the reflected light is a spectral waveform showing the relationship between the relative reflectance and the wavelength of the reflected light, but the spectrum of the reflected light may be a spectral waveform showing the relationship between the intensity itself of the reflected light and the wavelength of the reflected light.

[0035] The reference intensity is the intensity of light measured in advance for each wavelength, and the relative reflectance is calculated at each wavelength. Specifically, the relative reflectance is obtained by dividing the intensity of light (measured intensity) at each wavelength by the corresponding reference intensity. The reference intensity can be obtained, for example, by directly measuring the intensity of light irradiated from the film thickness measurement head 31, or by irradiating light from the film thickness measurement head 31 to a mirror and measuring the intensity of the reflected light from the mirror. Alternatively, the reference intensity may be the intensity of the reflected light from the silicon substrate measured by the spectroscope 33 when the silicon substrate (bare substrate) without a film formed thereon is being wet-polished on the stage 10 in the presence of water, or when the silicon substrate (bare substrate) is placed on the stage 10.

[0036] In actual polishing, the corrected measured intensity is obtained by subtracting the dark level (background intensity obtained under the condition of blocking light) from the measured intensity, and further, the corrected reference intensity is obtained by subtracting the above dark level from the reference intensity. Then, the relative reflectance is obtained by dividing the corrected measured intensity by the corrected reference intensity. Specifically, the relative reflectance R(λ) can be obtained using the following formula (1).

Equation

[0037] The spectrum analysis unit 34 determines the film thickness of the substrate W from the spectrum of the reflected light from the substrate W. A known method can be used to determine the film thickness from the spectrum of the reflected light. For example, a method of determining the film thickness from the frequency spectrum obtained by performing Fourier transform processing (typically fast Fourier transform processing) on the spectrum of the reflected light, or a method of determining the film thickness associated with the reference spectrum having the shape closest to the spectrum of the reflected light among a plurality of reference spectra.

[0038] The spectral analysis unit 34 includes a storage device 34a (see FIG. 1) storing a program for determining the thickness of the layer to be polished, and a processing device 34b (see FIG. 1) that executes calculations according to the instructions included in the program. The spectral analysis unit 34 is composed of at least one computer. The storage device 34a includes a main storage device such as a random access memory (RAM), and auxiliary storage devices such as a hard disk drive (HDD) and a solid state drive (SSD). Examples of the processing device 34b include a CPU (central processing unit) and a GPU (graphics processing unit). However, the specific configuration of the spectral analysis unit 34 is not limited to these examples.

[0039] The spectral analysis unit 34 transmits the determined thickness of the layer to be polished to the operation control unit 60 (see FIG. 3). The operation control unit 60 determines the polishing end point based on the determined thickness of the layer to be polished and controls the operation of the polishing unit 20. For example, the operation control unit 60 determines the polishing end point as the time when the determined thickness of the layer to be polished reaches the target value. In one embodiment, the polishing end point may be determined by measuring the combined thickness of the layer to be polished and the thickness of the underlying layer. The spectral analysis unit 34 for determining the thickness of the layer to be polished and the operation control unit 60 for controlling the polishing operation of the substrate W may be integrally configured. In this specification, examples of the film thickness of the substrate W include the thickness of the layer to be polished and the combined thickness of the layer to be polished and the thickness of the underlying layer.

[0040] FIGS. 5(a) to 5(c) are diagrams for explaining the operations of the polishing unit 20 and the film thickness measuring device 30. The polishing unit 20 and the film thickness measuring device 30 are configured to move in conjunction with each other. Specifically, the operation control unit 60 controls the polishing head movement mechanism 24 and the film thickness measuring head movement mechanism 37 so that the polishing head 21 and the film thickness measuring head 31 do not contact each other.

[0041] Fig. 5(a) shows a state where a part of the polishing head 21 is positioned above the substrate W on the stage 10, and the film thickness measurement head 31 is positioned above the substrate W on the stage 10. That is, the polishing head 21 is arranged at the polishing position, and the film thickness measurement head 31 is arranged at the measurement position. As shown by the arrow, the polishing head moving mechanism 24 moves the polishing head arm 23 in the direction in which the polishing head 21 moves toward the center of the substrate W, and the polishing head 21 presses the polishing pad 22 (see Fig. 2) against the substrate W to polish the substrate W. More specifically, the polishing head 21 polishes the substrate W by pressing the polishing pad 22 against the substrate W while moving in the radial direction of the substrate W. The substrate polishing apparatus 1 may include side stages (not shown) arranged on both sides in the moving direction of the polishing head 21 with the stage 10 interposed therebetween. The side stages are configured to support the polishing head 21 positioned outside the stage 10. Thereby, the substrate W can be polished uniformly without the pressing force of the polishing head 21 concentrating on the peripheral portion of the substrate W.

[0042] As shown by the arrow, the film thickness measurement head moving mechanism 37 measures the film thickness of the substrate W while moving the film thickness measurement head arm 36 in the direction in which the film thickness measurement head 31 moves toward the outside of the substrate W. More specifically, the film thickness measurement head 31 measures the film thickness of the substrate W while moving in the radial direction of the substrate W, and the film thickness measurement device 30 measures the film thickness of the substrate W. The film thickness measurement device 30 may measure the film thickness of the substrate W at predetermined time intervals, or may measure the film thickness at a predetermined measurement position on the substrate W.

[0043] FIG. 5(b) shows a state where the polishing head 21 is positioned above the center of the substrate W on the stage 10 and the film thickness measurement head 31 is positioned outside the substrate W on the stage 10. That is, the polishing head 21 is disposed at the polishing position, and the film thickness measurement head 31 is disposed at the non-measurement position. As indicated by the arrow, the polishing head moving mechanism 24 moves the polishing head arm 23 while the polishing head 21 crosses the substrate W, and the polishing head 21 presses the polishing pad 22 (see FIG. 2) against the substrate W to polish the substrate W. As indicated by the arrow, the film thickness measurement head moving mechanism 37 moves the film thickness measurement head arm 36 in a direction in which the film thickness measurement head 31 moves further outside the substrate W. Since the film thickness measurement head 31 is disposed at the non-measurement position, the film thickness of the substrate W is not measured.

[0044] FIG. 5(c) shows a state where the polishing head 21 is positioned outside the substrate W on the stage 10 and the film thickness measurement head 31 is positioned above the center of the substrate W on the stage 10. That is, the polishing head 21 is disposed at the non-polishing position, and the film thickness measurement head 31 is disposed at the measurement position. As indicated by the arrow, the polishing head moving mechanism 24 moves the polishing head arm 23 in a direction in which the polishing head 21 moves further outside the substrate W. Since the polishing head 21 is disposed at the non-polishing position, the substrate W is not polished. As indicated by the arrow, the film thickness measurement head moving mechanism 37 moves the film thickness measurement head arm 36 while the film thickness measurement head 31 crosses the substrate W to measure the film thickness of the substrate W. More specifically, the film thickness measurement head 31 moves in the radial direction of the substrate W, and the film thickness measurement device 30 measures the film thickness of the substrate W. The film thickness measurement device 30 may measure the film thickness of the substrate W every predetermined time, or may measure the film thickness at a predetermined measurement position on the substrate W.

[0045] As shown in FIGS. 5(a) to 5(c), the polishing head 21 and the film thickness measurement head 31 operate so as not to contact each other while swinging along a trajectory passing through the center of the substrate W on the stage 10.

[0046] Next, the details of the head nozzle 40 will be described. FIG. 6 is a diagram showing the arrangement of the first flow path system 71 and the second flow path system 72 when the head nozzle 40 is viewed from below. The head nozzle 40 includes a first flow path system 71 and a second flow path system 72 configured to form a liquid flow across the optical paths of the light from the film thickness measurement head 31 and the reflected light from the substrate W. The first flow path system 71 and the second flow path system 72 are two independent flow path systems configured to form two independent liquid flows.

[0047] The first flow path system 71 includes a fluid chamber 151, a first liquid supply flow path 152, a first liquid discharge flow path 153, and an opening 154. The second flow path system 72 includes a second liquid supply flow path 252, a second liquid discharge flow path 253, a liquid discharge port 254, and a liquid suction port 255.

[0048] When viewed from the axial direction of the head nozzle 40, the first flow path system 71 and the second flow path system 72 are respectively located on two lines L1 and L2 (imaginary lines indicated by dashed-dotted lines) that intersect at the center point O1 of the head nozzle 40. The first flow path system 71 and the second flow path system 72 are arranged at positions shifted by a predetermined angle α around the center point O1 of the head nozzle 40. That is, the fluid chamber 151, the first liquid supply flow path 152, the first liquid discharge flow path 153, the opening 154 of the first flow path system 71, and the second liquid supply flow path 252, the second liquid discharge flow path 253, the liquid discharge port 254, the liquid suction port 255 of the second flow path system 72 are arranged at positions separated from each other. The predetermined angle α between the two lines L1 and L2 is, for example, 30 degrees, but is not limited thereto.

[0049] The following describes the details of the configurations of the first flow path system 71 and the second flow path system 72. FIG. 7 is a cross-sectional view taken along line B-B of FIG. 6 schematically showing an embodiment of the first flow path system 71 of the head nozzle 40. The film thickness measurement head 31 has the tips of the light projection optical fiber cable 38 and the light reception optical fiber cable 39, and a fiber holding portion 41 that holds these tips. The head nozzle 40 has a shape that covers the tip of the film thickness measurement head 31. The first flow path system 71 of the head nozzle 40 has a fluid chamber 151, a first liquid supply flow path 152, a first liquid discharge flow path 153, and an opening 154. The fluid chamber 151 is provided on the optical path of the light irradiated from the film thickness measurement head 31 onto the surface of the substrate W and the reflected light from the substrate W received by the film thickness measurement head 31. The lower end 31a of the film thickness measurement head 31 faces the fluid chamber 151.

[0050] The first liquid supply flow path 152 and the first liquid discharge flow path 153 are connected to the fluid chamber 151. The first liquid supply flow path 152 is connected to the first liquid supply line 142 (see FIG. 1) at the first pipe connection portion 152b. The first liquid discharge flow path 153 is connected to the first liquid discharge line 143 (see FIG. 1) at the second pipe connection portion 153c. The first connection portion 152a between the first liquid supply flow path 152 and the fluid chamber 151 is located below the second connection portion 153a between the first liquid discharge flow path 153 and the fluid chamber 151. More specifically, the first connection portion 152a between the first liquid supply flow path 152 and the fluid chamber 151 is located at the lower part of the fluid chamber 151, and the second connection portion 153a between the first liquid discharge flow path 153 and the fluid chamber 151 is located at the upper part of the fluid chamber 151.

[0051] Since the first connection portion 152a between the first liquid supply channel 152 and the fluid chamber 151 is located at the lower part of the fluid chamber 151, the collision between the liquid flowing into the fluid chamber 151 from the first connection portion 152a and the liquid already present in the fluid chamber 151 is alleviated, and the generation of bubbles due to the collision of the liquids can be reduced. In addition, since the second connection portion 153a between the first liquid discharge channel 153 and the fluid chamber 151 is located at the upper part of the fluid chamber 151, the bubbles generated in the fluid chamber 151 can be quickly discharged through the first liquid discharge channel 153.

[0052] The opening 154 is provided on the optical path of the light irradiated from the film thickness measurement head 31 to the surface of the substrate W and the reflected light from the substrate W received by the film thickness measurement head 31. The opening 154 communicates with the lower end of the fluid chamber 151, and the width a1 of the opening 154 is smaller than the width a2 of the fluid chamber 151. Thereby, the bubbles generated in the fluid chamber 151 are dispersed to the upper part of the fluid chamber 151 without staying in the opening 154. In one embodiment, the width a1 of the opening 154 is in the range of 1.0 mm to 2.0 mm. This is to minimize the flow rate of the liquid flowing out from the fluid chamber 151 through the opening 154, prevent the dilution of the polishing liquid on the substrate W, and ensure the passage of the light emitted from the film thickness measurement head 31 and the reflected light from the substrate W.

[0053] The opening 154 is located within the bottom surface 40a of the head nozzle 40 and can be brought close to face the surface of the substrate W for measuring the film thickness of the substrate W. In one embodiment, the distance b1 from the lower end of the opening 154 to the surface of the substrate W, that is, from the bottom surface 40a of the head nozzle 40 to the surface to be polished 2, is in the range of 0.5 mm to 1.0 mm. This is also to minimize the flow rate of the liquid flowing out from the fluid chamber 151 through the opening 154 and prevent the dilution of the polishing liquid on the substrate W.

[0054] The light-projecting optical fiber cable 38 and the light-receiving optical fiber cable 39 may be of a bundle type in which a plurality of light-receiving optical fiber cables 39 are arranged outside a plurality of light-projecting optical fiber cables 38 and bundled, or the light-projecting optical fiber cable 38 and the light-receiving optical fiber cable 39 may not be bundled.

[0055] The width a2 of the fluid chamber 151 at the portion where the first connection portion 152a between the first liquid supply flow path 152 and the fluid chamber 151 is located is smaller than the width a3 of the fluid chamber 151 at the portion facing the lower end 31a of the film thickness measurement head 31. Thereby, the bubbles generated in the fluid chamber 151 are dispersed outside the optical path without staying on the optical path during film thickness measurement. The second connection portion 153a is located at the lower end of the film thickness measurement head 31. More specifically, the upper surface 153b of the first liquid discharge flow path 153 extending from the second connection portion 153a is at a position higher than the lower end of the film thickness measurement head 31. With such an arrangement, the bubbles are quickly discharged through the first liquid discharge flow path 153 without staying in the fluid chamber 151.

[0056] When the first supply valve 144 (see FIG. 1) is opened, the liquid flowing through the first liquid supply line 142 is supplied to the fluid chamber 151 through the first liquid supply flow path 152. The liquid supplied to the fluid chamber 151 is supplied from the opening 154 to the polished surface 2 of the substrate W. When the first discharge valve 145 (see FIG. 1) is opened, the liquid in the fluid chamber 151 flows through the first liquid discharge flow path 153 and the first liquid discharge line 143, and is discharged outside the first liquid discharge line 143 by the liquid pump 148. The first supply valve 144 and the first discharge valve 145 are configured such that the flow rate of the liquid flowing through the first liquid supply flow path 152 is larger than the flow rate of the liquid flowing through the first liquid discharge flow path 153.

[0057] The liquid supplied from the first liquid supply line 142 is, for example, pure water. The liquid may be any transparent liquid, such as a KOH solution used for a polishing liquid. When the first supply valve 144 and the first discharge valve 145 are opened, the fluid chamber 151 is filled with the liquid, and the liquid is supplied to the substrate W to remove the polishing liquid and polishing debris present on the substrate W. Since the optical path during film thickness measurement is filled with the transparent liquid, the film thickness of the substrate W being polished can be measured with high accuracy. The first supply valve 144 and the first discharge valve 145 may be constantly open during polishing of the substrate W regardless of the position of the film thickness measurement head 31, or may be opened only when the film thickness measurement head 31 is at the measurement position.

[0058] In one embodiment, the flow rate of the liquid flowing through the first liquid discharge channel 153 is in the range of 90% to 95% of the flow rate of the liquid flowing through the first liquid supply channel 152, and the flow rate of the liquid supplied from the opening 154 to the substrate W is in the range of 5% to 10% of the flow rate of the liquid flowing through the first liquid supply channel 152. By minimizing the flow rate of the liquid supplied from the opening 154, it is possible to prevent the polishing liquid on the substrate W from being diluted and the polishing performance from being degraded.

[0059] FIG. 8 is a cross-sectional view taken along line C-C of FIG. 6 schematically showing an embodiment of the second flow path system 72 of the head nozzle 40. FIG. 9 is a view of the head nozzle 40 according to this embodiment as seen from below. The second flow path system 72 of the head nozzle 40 has a second liquid supply channel 252, a second liquid discharge channel 253, a liquid discharge port 254, and a liquid suction port 255. The second liquid supply channel 252 is connected to the second liquid supply line 242 (see FIG. 1) at the third pipe connection portion 252a. The second liquid discharge channel 253 is connected to the second liquid discharge line 243 (see FIG. 1) at the fourth pipe connection portion 253a.

[0060] The liquid discharge port 254 communicates with the lower end of the second liquid supply channel 252. The second liquid supply channel 252 bends at the bending portion 252b, and the lower part of the second liquid supply channel 252 inclines toward the opening 154 of the first channel system 71. The liquid suction port 255 communicates with the lower end of the second liquid discharge channel 253. The second liquid discharge channel 253 bends at the bending portion 253b, and the lower part of the second liquid discharge channel 253 inclines toward the opening 154 of the first channel system 71. However, the second liquid supply channel 252 and the second liquid discharge channel 253 are not limited to the embodiment shown in FIG. 8. In one embodiment, the second liquid supply channel 252 and the second liquid discharge channel 253 do not have the bending portions 252b and 253b, and the entire second liquid supply channel 252 and the entire second liquid discharge channel 253 may incline toward the opening 154 of the first channel system 71.

[0061] As shown in FIG. 9, the liquid discharge port 254 and the liquid suction port 255 are located within the bottom surface 40a of the head nozzle 40, similar to the opening 154. The liquid discharge port 254 and the liquid suction port 255 are located on both sides of the opening 154, and the opening 154 is located between the liquid discharge port 254 and the liquid suction port 255. More specifically, the liquid discharge port 254 and the liquid suction port 255 are symmetrically arranged with respect to the opening 154. The liquid discharge port 254 is located upstream of the opening 154 and the liquid suction port 255 in the rotation direction P of the substrate W.

[0062] Both the liquid discharge port 254 and the liquid suction port 255 are larger than the opening 154. Also, the liquid suction port 255 is larger than the liquid discharge port 254. That is, the inner diameter of the lower end of the second liquid discharge channel 253 is larger than the inner diameter of the lower end of the second liquid supply channel 252. The liquid discharge port 254 can approach and face the surface of the substrate W to supply liquid onto the surface of the substrate W. The liquid suction port 255 can approach and face the surface of the substrate W to suck the liquid on the surface of the substrate W. In one embodiment, the distance c1 from the lower ends of the liquid discharge port 254 and the liquid suction port 255 to the surface of the substrate W, that is, from the bottom surface 40a of the head nozzle 40 to the surface to be polished 2, is in the range of 0.5 mm to 1.0 mm.

[0063] When the second supply valve 244 (see FIG. 1) is opened, the liquid flowing through the second liquid supply line 242 is supplied from the liquid discharge port 254 onto the surface (polishing surface 2) of the substrate W through the second liquid supply passage 252. When the second discharge valve 245 (see FIG. 1) is opened, the liquid on the surface (polishing surface 2) of the substrate W is sucked into the liquid suction port 255, flows through the second liquid discharge passage 253 into the second liquid discharge line 243, and is discharged outside the second liquid discharge line 243 by the liquid pump 248. In one embodiment, the second supply valve 244 is configured such that the flow rate of the liquid supplied from the liquid discharge port 254 to the substrate W is larger than the flow rate of the liquid flowing through the opening 154.

[0064] When the second supply valve 244 and the second discharge valve 245 are opened, the liquid is supplied onto the surface of the substrate W from the liquid discharge port 254, flows through the gap between the opening 154 and the substrate W along the rotation direction P of the substrate W, and heads toward the liquid suction port 255. This liquid is mixed with the liquid flowing out from the opening 154. That is, the flow of the liquid from the liquid discharge port 254 toward the liquid suction port 255 and the flow of the liquid passing through the opening 154 merge, and the liquid forming these two flows is sucked into the liquid suction port 255.

[0065] In this way, the mixed liquid flows along the rotation direction P of the substrate W and is sucked through the liquid suction port 255. Due to this liquid flow, the polishing liquid and polishing debris existing between the opening 154 and the substrate W are removed. Since the optical path during the film thickness measurement between the opening 154 and the substrate W is filled with a transparent liquid, the film thickness of the substrate W can be measured with high accuracy. In particular, according to the present embodiment, since the flow of the liquid from the liquid discharge port 254 toward the liquid suction port 255 is formed on the surface of the substrate W, even when the rotation speed of the substrate W is high, the optical path between the opening 154 and the substrate W can be filled with a transparent liquid.

[0066] The liquid supplied from the second liquid supply line 242 to the substrate W is, for example, pure water. The liquid may be any transparent liquid, such as a KOH solution used for a polishing liquid. The second supply valve 244 and the second discharge valve 245 may be constantly open during the polishing of the substrate W regardless of the position of the film thickness measurement head 31, or may be open only when the film thickness measurement head 31 is at the measurement position. During the film thickness measurement of the substrate W, the first supply valve 144, the first discharge valve 145 of the first flow path system 71 and the second supply valve 244, the second discharge valve 245 of the second flow path system 72 are simultaneously open.

[0067] FIG. 10 is a flowchart for explaining an example of the process of measuring the film thickness of the substrate W. In step S101, the stage 10 supports the substrate W with the polished surface 2 of the substrate W facing upward, and the stage rotation mechanism rotates the stage 10. In step S102, the polishing unit 20 starts polishing the substrate W while supplying the polishing liquid from the polishing liquid supply nozzle 28 to the substrate W.

[0068] In step S103, the polishing head moving mechanism 24 starts moving the polishing head 21, and the film thickness measurement head moving mechanism 37 starts moving the film thickness measurement head 31. At this time, the polishing head 21 and the film thickness measurement head 31 move so as not to contact each other. In step S104, the first supply valve 144 and the first discharge valve 145 are opened, and while supplying liquid to the Fluid chamber 151 of the head nozzle 40, Fluid chamber 151 the liquid is discharged from. Further, the second supply valve 244 and the second discharge valve 245 are opened, and the liquid supply from the head nozzle 40 is started.

[0069] In step S105, the film thickness measurement head 31 is moved to the measurement position, and the opening 154 of the head nozzle 40, the liquid discharge port 254, and the liquid suction port 255 are brought close to the surface of the substrate W. Liquid flows out through the opening 154 of the head nozzle 40, and at the same time, liquid is supplied from the liquid discharge port 254 to the substrate W, and the liquid on the substrate W is sucked through the liquid suction port 255. On the surface of the substrate W, a liquid flow is formed from the liquid discharge port 254 toward the liquid suction port 255. The opening 154 faces this liquid flow, and the liquid flowing out from the opening 154 merges into the liquid flow from the liquid discharge port 254 toward the liquid suction port 255.

[0070] In step S106, the light source 32 emits light, and the light is irradiated from the film thickness measurement head 31 through the fluid chamber 151 and the opening 154 onto the surface of the substrate W. In step S107, the film thickness measurement head 31 receives the reflected light from the substrate W through the fluid chamber 151 and the opening 154. Both the light from the film thickness measurement head 31 and the reflected light from the substrate W pass through the liquid flowing in the fluid chamber 151, the liquid flowing in the opening 154, and the liquid flowing from the liquid discharge port 254 to the liquid suction port 255, so a good optical path can be ensured. In step S108, the spectroscope 33 measures the intensity of the reflected light from the substrate W for each wavelength and sends the intensity measurement data of the reflected light to the spectrum analysis unit 34. The spectrum analysis unit 34 generates the spectrum of the reflected light from the intensity measurement data of the reflected light and determines the film thickness of the substrate W.

[0071] In step S109, it is determined whether or not the determined film thickness of the substrate W has reached the target value. When the determined film thickness of the substrate W has reached the target value (''YES'' in step S109), the polishing unit 20 finishes polishing the substrate W (step S110). When the determined film thickness of the substrate W has not reached the target value (''NO'' in step S109), the polishing unit 20 continues to polish the substrate W and repeats steps S105 to S109.

[0072] FIG. 11 is a cross-sectional view schematically showing another embodiment of the second flow path system 72 of the head nozzle 40. FIG. 12 is a view of the head nozzle 40 according to the embodiment shown in FIG. 11 as seen from below. The second flow path system 72 shown in FIG. 11 further includes a liquid collecting groove 257. The liquid collecting groove 257 is located within the bottom surface 40a of the head nozzle 40. The liquid collecting groove 257 is a depression connected to the liquid suction port 255, and the liquid collecting groove 257 communicates with the second liquid discharge flow path 253 through the liquid suction port 255. The liquid collecting groove 257 can be brought close to and opposed to the surface of the substrate W in order to collect and discharge the liquid on the surface of the substrate W. In one embodiment, the height d1 of the liquid collecting groove 257, that is, the height from the bottom surface 40a of the head nozzle 40 to the upper end of the liquid collecting groove 257, is in the range of 0.3 mm to 5.0 mm.

[0073] As shown in FIG. 12, the liquid collecting groove 257 is located upstream of the liquid suction port 255 and downstream of the opening 154 in the rotational direction P of the substrate W. The liquid collecting groove 257 has a substantially elliptical shape when the head nozzle 40 is viewed from below. The width d2 of the liquid collecting groove 257 is larger than the width d3 of the liquid suction port 255. The width d2 of the liquid collecting groove 257 is the width in a direction substantially orthogonal to the rotational direction P of the substrate W, and the width d3 of the liquid suction port 255 is the width in a direction substantially orthogonal to the rotational direction P of the substrate W.

[0074] As shown by the arrow in FIG. 12, when the liquid supplied onto the surface of the substrate W from the liquid discharge port 254 flows along the rotational direction P of the substrate W and spreads outward, it is collected by the liquid collecting groove 257 and discharged through the second liquid discharge flow path 253. This is to prevent the polishing liquid on the substrate W from being diluted and the polishing performance from being deteriorated by collecting the liquid flowing out from the opening 154 and the liquid discharge port 254 into the liquid collecting groove 257.

[0075] The liquid collecting groove 257 is not limited to the embodiment shown in FIG. 12, and may have, for example, an elliptical shape or a substantially fan shape as long as the width d2 of the liquid collecting groove 257 is larger than the width d3 of the liquid suction port 255.

[0076] The above-described embodiments are described for the purpose of enabling a person having ordinary skill in the technical field to which the present invention pertains to practice the present invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is construed in the broadest scope in accordance with the technical idea defined by the claims.

Explanation of Reference Numerals

[0077] 1 Substrate polishing apparatus 2 Polished surface 10 Stage 20 Polishing unit 21 Polishing head 22 Polishing pad 22a Polishing surface 23 Polishing head arm 24 Polishing head moving mechanism 25 Rotating shaft 26 Polishing head rotating mechanism 28 Polishing liquid supply nozzle 30 Film thickness measuring device 31 Film thickness measuring head 32 Light source 33 Spectrometer 34 Spectrum analysis unit 34a Storage device 34b Processing device 36 Film thickness measuring head arm 37 Film thickness measuring head moving mechanism 38 Light projection optical fiber cable 39 Light reception optical fiber cable 40 Head nozzle 41 Fiber holding part 60 Operation control unit 60a Storage device 60b Processing device 71 First flow path system 72 Second flow path system 142 First liquid supply line 143 First liquid discharge line 144 First supply valve 145 First discharge valve 146, 147 Flow meters 148 Liquid pump 151 Fluid chamber 152 First liquid supply flow path 152a First connection part 152b First pipe connection part 153 First liquid discharge flow path 153a Second connection part 153b Upper surface 153c Second pipe connection part 154 Opening 242 Second liquid supply line 243 Second liquid discharge line 244 Second supply valve 245 Second discharge valve 246, 247 Flow meters 248 Liquid pump 252 Second liquid supply flow path 252a Third pipe connection part 252b Bending part 253 Second liquid discharge flow path 253a Fourth pipe connection part 253b Bending part 254 Liquid discharge port 255 Liquid suction port 257 Liquid collecting groove

Claims

1. A stage that supports the polished surface of the substrate facing upward and rotates the substrate, A polishing head that holds a polishing pad having a polishing surface for polishing the substrate supported by the stage, A polishing liquid supply nozzle that supplies polishing liquid onto the surface of the substrate, A film thickness measurement head that irradiates light onto a measurement area on the surface of the substrate on the stage and receives reflected light from the measurement area, A spectrum analysis unit that generates a spectrum of the reflected light and determines the film thickness of the substrate from the spectrum, A head nozzle to which the film thickness measurement head is attached, The head nozzle includes a first flow path system and a second flow path system that form a flow of liquid crossing the optical paths of the light and the reflected light, The first flow path system has an opening located on the optical path, The second flow path system has a liquid discharge port and a liquid suction port. The liquid discharge port is located on one side of the opening, and the liquid suction port is located on the opposite side of the liquid discharge port across the opening. A substrate polishing apparatus.

2. The substrate polishing apparatus according to claim 1, wherein the liquid discharge port and the liquid suction port are symmetrically arranged with respect to the opening.

3. The substrate polishing apparatus according to claim 1 or 2, wherein the opening, the liquid discharge port, and the liquid suction port are located within the bottom surface of the head nozzle.

4. The substrate polishing apparatus according to any one of claims 1 to 3, wherein the liquid discharge port is located upstream of the opening and the liquid suction port in the rotational direction of the substrate.

5. The first flow path system includes: A fluid chamber provided on the optical path, A first liquid supply flow path for supplying liquid to the fluid chamber, A first liquid discharge flow path for discharging liquid from the fluid chamber, It has an opening that communicates with the lower end of the fluid chamber and can be close to the surface of the substrate, The second flow path system includes: A second liquid supply flow path for supplying liquid onto the surface of the substrate, A second liquid discharge flow path for discharging liquid on the surface of the substrate, A liquid discharge port that communicates with the second liquid supply flow path and can be close to the surface of the substrate, The substrate polishing apparatus according to any one of claims 1 to 4, which has a liquid suction port that communicates with the second liquid discharge flow path and can be close to the surface of the substrate.

6. The liquid discharge port and the liquid suction port are both larger than the opening, the substrate polishing apparatus according to any one of claims 1 to 5.

7. The liquid suction port is larger than the liquid discharge port, the substrate polishing apparatus according to any one of claims 1 to 6.

8. The second flow path system further includes a liquid collecting groove connected to the liquid suction port and capable of approaching the surface of the substrate. The liquid collecting groove is located upstream of the liquid suction port in the rotational direction of the substrate. The width of the liquid collecting groove is larger than the width of the liquid suction port, the substrate polishing apparatus according to any one of claims 1 to 7.

9. Support the polished surface of the substrate upward and rotate the substrate. While supplying a polishing liquid to the surface of the substrate, press a polishing pad having a polishing surface against the substrate with a polishing head to polish the substrate. While flowing a liquid through an opening of a first flow path system provided in a head nozzle close to the surface of the substrate, and supplying a liquid onto the surface of the substrate from a liquid discharge port of a second flow path system provided in the head nozzle, and sucking the liquid on the surface of the substrate through a liquid suction port of the second flow path system, irradiate light from a film thickness measurement head through the opening onto a measurement region on the surface of the substrate. Receive reflected light from the measurement region through the opening with the film thickness measurement head. The method includes a step of determining the film thickness of the substrate from the spectrum of the reflected light. The first flow path system and the second flow path system are configured to form a flow of liquid crossing the optical paths of the light and the reflected light. The liquid discharge port is located on one side of the opening, and the liquid suction port is located on the side opposite to the liquid discharge port with the opening therebetween, a substrate polishing method.

10. The step of flowing a liquid through the opening provided in the head nozzle is a step of flowing a liquid through a fluid chamber provided in the head nozzle and the opening. The step of irradiating light from the film thickness measurement head through the opening onto a measurement region on the surface of the substrate is a step of irradiating light from the film thickness measurement head through the fluid chamber and the opening onto a measurement region on the surface of the substrate. The step of receiving, through the opening, the reflected light from the measurement region with the film thickness measurement head is the step of receiving, through the opening and the fluid chamber, the reflected light from the measurement region with the film thickness measurement head, according to the substrate polishing method of claim 9.

11. The liquid discharge port and the liquid suction port are arranged symmetrically with respect to the opening, according to the substrate polishing method of claim 9 or 10.

12. The opening, the liquid discharge port, and the liquid suction port are located within the bottom surface of the head nozzle, according to the substrate polishing method of any one of claims 9 to 11.

13. The liquid discharge port is located upstream of the opening and the liquid suction port in the rotational direction of the substrate, according to the substrate polishing method of any one of claims 9 to 12.

14. Both the liquid discharge port and the liquid suction port are larger than the opening, according to the substrate polishing method of any one of claims 9 to 13.

15. The liquid suction port is larger than the liquid discharge port, according to the substrate polishing method of any one of claims 9 to 14.

16. The head nozzle has a liquid collection groove connected to the liquid suction port, The liquid collection groove is located upstream of the liquid suction port in the rotational direction of the substrate, The width of the liquid collection groove is larger than the width of the liquid suction port, according to the substrate polishing method of any one of claims 9 to 15.

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