JP2023086233A - Substrate polishing device and substrate polishing method - Google Patents

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

The present invention relates to a substrate polishing apparatus and substrate polishing method, and more particularly to a substrate polishing apparatus and substrate polishing method for measuring the film thickness of a substrate being polished.

In chemical mechanical polishing (CMP), a polishing liquid containing abrasive grains such as silica (SiO ₂ ) 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. It is a technique to perform The substrate polishing apparatus used in the CMP process includes a type in which the surface to be polished of the substrate faces upward (face-up type) and a type in which the surface to be polished of the substrate faces downward (face-down type).

A face-up type substrate polishing apparatus places a substrate on a stage with the surface to be polished facing upward, and rotates a polishing pad having a diameter smaller than that of the substrate so that the polishing pad is brought into contact with the substrate. configured to polish the 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 a substrate during polishing, the surface of the substrate is irradiated with light by an optical film thickness measuring device installed in the substrate polishing apparatus, and the spectral waveform of the light reflected from the substrate is used. There are techniques for determining film thickness.

JP 2016-78156 A JP-A-9-298176

However, since foreign matters such as polishing liquid and polishing dust are present on the surface of the substrate being polished, the light transmittance decreases when light is irradiated by the film thickness measuring device and reflected light is received. For this reason, it has been difficult to measure the film thickness of the substrate being polished with high accuracy.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a substrate polishing apparatus capable of measuring the film thickness of a substrate being polished with high accuracy without reducing the light transmittance.

In one aspect, a stage that supports a substrate with the surface to be polished facing upward and rotates the substrate, and 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; and a film thickness measuring head that irradiates a measurement area on the surface of the substrate on the stage with light and receives light reflected 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 first channel system and a second channel system for forming a liquid flow across an optical path of light, the first channel system having an opening positioned on the optical path; A substrate polishing apparatus is provided, wherein the system has a liquid outlet and a liquid inlet, and wherein the liquid outlet and the liquid inlet are located on opposite sides of the opening.

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

In one aspect, the first channel system includes a fluid chamber provided on the optical path, a first liquid supply channel for supplying liquid to the fluid chamber, and a liquid for discharging liquid from the fluid chamber. and the opening that communicates with the lower end of the fluid chamber and is accessible to the surface of the substrate. a second liquid supply channel for supplying the liquid, a second liquid discharge channel for discharging the liquid on the surface of the substrate, and a second liquid supply channel communicating with the second liquid supply channel and close to the surface of the substrate and the liquid suction port that communicates with the second liquid discharge channel and that can be brought close to the surface of the substrate.

In one aspect, both the liquid ejection port and the liquid suction port are larger than the opening.
In one aspect, the liquid inlet is larger than the liquid outlet.
In one aspect, the second channel system further includes a liquid collecting groove that is connected to the liquid suction port and is accessible to the surface of the substrate, and the liquid collecting groove extends in the rotation direction of the substrate in the direction of rotation of the substrate. Located upstream of the liquid suction port, the width of the liquid collecting groove is greater than the width of the liquid suction port.

In one aspect, the substrate is supported with the surface to be polished facing upward, the substrate is rotated, and a polishing pad having a polishing surface is pressed against the substrate by a polishing head while a polishing liquid is supplied to the surface of the substrate. polishing the substrate, supplying the liquid onto the surface of the substrate from a liquid ejection port provided in the head nozzle while flowing the liquid into an opening provided in a head nozzle adjacent to the surface of the substrate; Further, while sucking the liquid on the surface of the substrate through the liquid suction port, light is emitted from the film thickness measurement head through the opening to the measurement region on the surface of the substrate, and light is emitted from the measurement region through the opening. receiving reflected light with the film thickness measuring head and determining the film thickness of the substrate from the spectrum of the reflected light, wherein the liquid ejection port and the liquid suction port are positioned on both sides of the opening. , a substrate polishing method is provided.

In one aspect, the step of flowing a liquid through the opening provided in the head nozzle is a step of flowing the liquid through a fluid chamber provided in the head nozzle and the opening, wherein The step of irradiating the measurement region on the surface of the substrate with light through the portion is a step of irradiating the measurement region on the surface of the substrate with light from the film thickness measurement head through the fluid chamber and the opening. and the step of receiving the reflected light from the measurement region through the opening with the film thickness measurement head is a step of receiving the reflected light from the measurement region with the film thickness measurement head through the opening and the fluid chamber. be.

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

In one aspect, both the liquid ejection port and the liquid suction port are larger than the opening.
In one aspect, the liquid inlet is larger than the liquid outlet.
In one aspect, the head nozzle has a liquid collecting groove connected to the liquid suction port, and the liquid collecting groove is positioned upstream of the liquid suction port in the rotation direction of the substrate. and the width of the liquid collecting groove is larger than the width of the liquid suction port.

According to the present invention, the head nozzle is provided with the first flow path system and the second flow path system, and these two separate liquid supply/drainage mechanisms remove the polishing liquid and polishing debris present on the optical path. be. 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.

The liquid supplied onto the surface of the substrate from the liquid ejection port of the second channel system flows along the surface of the substrate through the gap between the opening of the first channel system and the substrate, and the liquid in the second channel system Sucked in from the suction port. The flow of the liquid removes the polishing liquid and polishing dust existing between the opening and the substrate, so that the film thickness of the substrate being polished can be measured with high accuracy.

1 is a top view showing one embodiment of a substrate polishing apparatus; FIG. FIG. 2 is a side view of the substrate polishing apparatus shown in FIG. 1 as viewed in the direction indicated by an arrow A; It is a schematic diagram for demonstrating the principle of an optical film-thickness-measurement apparatus. FIG. 4 is a diagram showing an example of spectral waveforms generated by a spectrum analysis section; 5(a) to 5(c) are diagrams for explaining the operation of the polishing unit and the film thickness measuring device. It is a figure which shows the arrangement|positioning of a 1st flow-path system and a 2nd flow-path system when a head nozzle is seen from the bottom. FIG. 7 is a cross-sectional view along the line BB in FIG. 6 schematically showing one embodiment of the first channel system. FIG. 7 is a cross-sectional view taken along the line CC of FIG. 6 schematically showing one embodiment of the second channel system. It is the figure which looked at the head nozzle which concerns on this embodiment from the bottom. 4 is a flow chart illustrating an example of a process for measuring the film thickness of a substrate; FIG. 4 is a cross-sectional view schematically showing another embodiment of the second flow path system of the head nozzle; FIG. 12 is a bottom view of the head nozzle according to the embodiment shown in FIG. 11;

BEST MODE FOR CARRYING OUT THE INVENTION 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 explanations are omitted.
FIG. 1 is a top view showing one 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. FIG. As shown in FIGS. 1 and 2, the substrate polishing apparatus 1 includes a stage 10 for supporting the substrate W, a polishing unit 20 for polishing the substrate W, and a film thickness measuring unit for measuring the film thickness of the substrate W. A device 30 is provided. Examples of substrates 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.

The stage 10 supports a substrate W to be polished with its surface 2 to be polished 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. FIG.

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 a 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 and 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 around the rotating shaft 25 . It is

The polishing head arm 23 is further connected to a polishing head moving mechanism 24. 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 the polishing position and the non-polishing position. move between The polishing position is a position where the polishing head 21 can polish the substrate W, that is, a position where at least part of the polishing head 21 is arranged 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 arranged outside the substrate W on the stage 10 . 1 and 2, the polishing head 21 is arranged at the non-polishing position.

The two polishing liquid supply nozzles 28 are connected to the polishing head arm 23 , and the tips of the polishing liquid supply nozzles 28 are arranged on both sides of the polishing head 21 in the moving direction of the polishing head 21 . The two polishing liquid supply nozzles 28 are configured to supply polishing liquid containing abrasive grains such as silica (SiO ₂ ) or cleaning water onto the surface of the substrate W. As shown in FIG.

Operations of the stage rotation mechanism and the polishing unit 20 are controlled by the operation control section 60 . The motion control section 60 is electrically connected to the stage rotation mechanism, the polishing head moving mechanism 24 and the polishing head rotation mechanism 26 . 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 section 60 .

The operation control section 60 is composed of at least one computer. The operation control section 60 includes a storage device 60a storing a program for operating the substrate polishing apparatus 1, and a processing device 60b for executing operations 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 solid state drive (SSD). Examples of the processing device 60b include a CPU (central processing unit) and a GPU (graphic processing unit). However, the specific configuration of the operation control unit 60 is not limited to these examples.

The substrate W is polished as follows. The operation control unit 60 supplies the polishing liquid from the polishing liquid supply nozzle 28 while rotating the stage 10 and the substrate W. As shown in FIG. The motion 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 . While the polishing pad 22 held by the polishing head 21 is rotated by the polishing head rotating mechanism 26, the polishing head 21 moves the polishing surface 22a of the polishing pad 22 onto the substrate W while the polishing liquid is present on the substrate W. Press against the polishing surface 2. 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 .

The film thickness measurement device 30 is an optical film thickness measurement device, and includes a light source 32, a spectroscope 33, a spectrum analysis section 34, a film thickness measurement head 31, a head nozzle 40, and a film thickness measurement head arm 36. and a film thickness measuring head moving mechanism 37 . The film thickness measuring head 31 has respective ends of a light-projecting optical fiber cable 38 and a light-receiving optical fiber cable 39 . A light source 32 that emits light is coupled to a light-projecting fiber optic cable 38 . The spectroscope 33 is connected to a light receiving optical fiber cable 39 . Light source 32 and spectroscope 33 are connected to spectrum analysis section 34 .

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 moving mechanism 37 . The film thickness measuring head moving mechanism 37 swings the film thickness measuring head arm 36 in the direction indicated by the arrow to move the film thickness measuring head 31 between the measuring position and the non-measuring position. The measurement position is a position where the film thickness measurement head 31 can measure the film thickness of the substrate W, that is, a position where the film thickness measurement head 31 is arranged above the substrate W on the stage 10 . The non-measurement position is a position where the film thickness measurement head 31 cannot measure the film thickness of the substrate W, that is, a position where the film thickness measurement head 31 is arranged outside the substrate W on the stage 10 . In FIGS. 1 and 2, the film thickness measuring head 31 is arranged at the measuring position. The film thickness measuring head moving mechanism 37 is electrically connected to the operation control section 60 , and the operation of the film thickness measuring head moving mechanism 37 is controlled by the operation control section 60 .

The film thickness measuring head 31 including the tip of the light emitting optical fiber cable 38 and the tip of the light receiving optical fiber cable 39 is attached to the head nozzle 40 . The head nozzle 40 includes a first channel system 71 and a second channel system 72, details of which will be described later. The first flow path system 71 is connected to a first liquid supply line 142 for supplying liquid to the head nozzles 40 and a first liquid discharge line 143 for discharging liquid from the head nozzles 40 . The second flow path system 72 is connected to a second liquid supply line 242 for supplying liquid to the head nozzles 40 and a second liquid discharge line 243 for discharging liquid from the head nozzles 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 pure water, for example. The liquid may be any transparent liquid, such as a KOH solution used as a polishing liquid.

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 . Attached to the first liquid discharge line 143 is a first discharge valve 145, a flow meter 147, and a liquid pump 148 such as an ejector. Attached to the second liquid discharge line 243 is a second discharge valve 245, a flow meter 247, and a liquid pump 248 such as an ejector. The first supply valve 144, the second supply valve 244, the first exhaust valve 145, and the second exhaust valve 245 may be manual or the first supply valve 144, the second supply valve 244, the first exhaust valve. The valve 145 and the second discharge valve 245 are connected to the operation control section 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 are controlled by the operation control section 60 . may be controlled by Details of the head nozzle 40 will be described later.

FIG. 3 is a schematic diagram for explaining the principle of the optical film thickness measuring device 30. As shown in FIG. 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 ends of a light-projecting optical fiber cable 38 and a light-receiving optical fiber cable 39, and is arranged to face the surface of the substrate W. As shown in FIG. Although the head nozzle 40 is attached to the film thickness measuring head 31 in this embodiment, the configuration of the head nozzle 40 is omitted in FIG. 3 for the sake of simplicity of explanation.

The light emitted from the light source 32 is transmitted to the film thickness measurement head 31 through the optical fiber cable 38 for light projection, and the surface of the substrate W is irradiated with the light from the film thickness measurement head 31 including the tip of the optical fiber cable 38 for light projection. 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 sent to the spectroscope 33 through the light receiving optical fiber cable 39 . The spectroscope 33 decomposes the reflected light according to wavelength and measures the intensity of the reflected light at each wavelength. The reflected light intensity measurement data is sent to the spectrum analysis unit 34 .

The spectrum analyzer 34 is configured to generate a spectrum of reflected light from the intensity measurement data of the reflected light. The spectrum of reflected light is represented as a line graph (that is, spectral waveform) showing the relationship between the wavelength and intensity of reflected light. The intensity of reflected light can also be expressed as a relative value such as reflectance or relative reflectance.

The light irradiated to the substrate W is reflected at the interface between the medium (water in the example of FIG. 3) and the layer to be polished and the interface between the layer to be polished and the lower layer, and the waves of light reflected at these interfaces have a finger in the pie. The manner in which the light waves interfere changes depending on the thickness of the layer to be polished (that is, the optical path length). Therefore, the spectrum generated from the reflected light from the substrate W varies according to the thickness of the layer to be polished. The spectrum analysis unit 34 determines the film thickness of the substrate W based on the optical information contained in the spectrum of the reflected light.

FIG. 4 is a diagram showing an example of the spectrum generated by the spectrum analysis section 34. As shown in FIG. 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 reflected light, and is the ratio of the intensity of light to a predetermined reference intensity. By dividing the light intensity (actually measured intensity) at each wavelength by a predetermined reference intensity, unnecessary noise such as variations in intensity specific to the optical system of the apparatus and the light source can be removed from the measured intensity. In the example shown in FIG. 4, the spectrum of the reflected light is a spectral waveform that indicates the relationship between the relative reflectance and the wavelength of the reflected light. It may be a spectral waveform showing the relationship of

The reference intensity is the pre-measured intensity of light for each wavelength, and the relative reflectance is calculated at each wavelength. Specifically, the relative reflectance is obtained by dividing the light intensity (measured intensity) at each wavelength by the corresponding reference intensity. The reference intensity is obtained, for example, by directly measuring the intensity of light emitted from the film thickness measuring head 31, or by irradiating the mirror with light from the film thickness measuring head 31 and measuring the intensity of the reflected light from the mirror. can get. Alternatively, the reference intensity is obtained when a silicon substrate (bare substrate) on which no film is formed is water-polished on the stage 10 in the presence of water, or when the silicon substrate (bare substrate) is placed on the stage 10. It may be the intensity of the reflected light from the silicon substrate measured by the spectroscope 33 when the light is on.

ここで、λは基板Ｗから反射した光の波長であり、Ｅ（λ）は波長λでの強度であり、Ｂ（λ）は波長λでの基準強度であり、Ｄ（λ）は光を遮断した条件下で測定された波長λでの背景強度（ダークレベル）である。 In actual polishing, the dark level (background intensity obtained under the condition that light is blocked) is subtracted from the measured intensity to obtain the corrected measured intensity, and the dark level is further subtracted from the reference intensity to obtain the corrected reference intensity. , and 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).

where λ is the wavelength of the light reflected from the substrate W, E(λ) is the intensity at wavelength λ, B(λ) is the reference intensity at wavelength λ, and D(λ) is the light Background intensity (dark level) at wavelength λ measured under blocked conditions.

The spectrum analysis unit 34 determines the film thickness of the substrate W from the spectrum of the reflected light from the substrate W. FIG. 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 reflected light, or a spectrum of reflected light among a plurality of reference spectra There are methods such as determining the film thickness associated with the reference spectrum whose shape is closest to .

The spectrum 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. ). The spectrum 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 an auxiliary storage device such as a hard disk drive (HDD) and solid state drive (SSD). Examples of the processing device 34b include a CPU (central processing unit) and a GPU (graphic processing unit). However, the specific configuration of the spectrum analysis unit 34 is not limited to these examples.

The spectrum 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 section 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 at which the determined thickness of the layer to be polished reaches the target value. In one embodiment, the thickness of the layer to be polished plus the thickness of the underlying layer may be measured to determine the polishing endpoint. The spectrum 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 integrated. In this specification, examples of the film thickness of the substrate W include the thickness of the layer to be polished and the sum of the thickness of the layer to be polished and the thickness of the lower layer.

5A to 5C are diagrams for explaining the operation of the polishing unit 20 and the film thickness measuring device 30. FIG. The polishing unit 20 and the film thickness measuring device 30 are configured to move together. Specifically, the operation control unit 60 controls the polishing head moving mechanism 24 and the film thickness measuring head moving mechanism 37 so that the polishing head 21 and the film thickness measuring head 31 do not contact each other.

5A shows a state in which 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. FIG. . That is, the polishing head 21 is arranged at the polishing position, and the film thickness measuring head 31 is arranged at the measuring position. The polishing head moving mechanism 24 causes the polishing head 21 to move the polishing pad 22 (see FIG. 2) to the substrate W while moving the polishing head arm 23 in the direction in which the polishing head 21 moves toward the center of the substrate W, as indicated by the arrow. The substrate W is polished by pressing. 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. As shown in FIG. The substrate polishing apparatus 1 may include side stages (not shown) arranged on both sides of the stage 10 in the moving direction of the polishing head 21 . The side stage is configured to support a polishing head 21 located outside the stage 10 . As a result, the pressing force of the polishing head 21 is not concentrated on the peripheral portion of the substrate W, and the substrate W can be uniformly polished.

The film thickness measuring head moving mechanism 37 measures the film thickness of the substrate W while moving the film thickness measuring head arm 36 in the direction in which the film thickness measuring head 31 faces the outside of the substrate W as indicated by the arrow. More specifically, the film thickness measuring device 30 measures the film thickness of the substrate W while the film thickness measuring head 31 moves in the radial direction of the substrate W. FIG. 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. FIG.

5B shows a state in which 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. FIG. That is, the polishing head 21 is arranged at the polishing position, and the film thickness measuring head 31 is arranged at the non-measurement position. The polishing head moving mechanism 24 moves the polishing head arm 23 so that the polishing head 21 traverses the substrate W as indicated by an arrow, while the polishing head 21 presses the polishing pad 22 (see FIG. 2) against the substrate W. to polish the substrate W. The film thickness measuring head moving mechanism 37 moves the film thickness measuring head arm 36 in the direction in which the film thickness measuring head 31 faces further outside the substrate W, as indicated by the arrow. Since the film thickness measurement head 31 is arranged at the non-measurement position, the film thickness of the substrate W is not measured.

FIG. 5C shows a state in which 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 arranged at the non-polishing position, and the film thickness measuring head 31 is arranged at the measuring position. The polishing head moving mechanism 24 moves the polishing head arm 23 in the direction in which the polishing head 21 faces further outside of the substrate W, as indicated by the arrow. Since the polishing head 21 is arranged at the non-polishing position, the substrate W is not polished. The film thickness measuring head moving mechanism 37 measures the film thickness of the substrate W while moving the film thickness measuring head arm 36 so that the film thickness measuring head 31 traverses the substrate W as indicated by an arrow. More specifically, the film thickness measuring device 30 measures the film thickness of the substrate W while the film thickness measuring head 31 moves in the radial direction of the substrate W. FIG. 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. FIG.

As shown in FIGS. 5(a) to 5(c), the polishing head 21 and the film thickness measuring head 31 swing on a track that passes through the center of the substrate W on the stage 10, while the polishing head 21 and the film thickness measuring head 31 swing. It operates so that the measuring head 31 does not come into contact with each other.

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

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

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 defined by two lines L1 and L2 that intersect at the center point O1 of the head nozzle 40 (an imaginary line indicated by a dashed dotted line). ), respectively. The first channel system 71 and the second channel 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 channel 152 , the first liquid discharge channel 153 and the opening 154 of the first channel system 71 , the second liquid supply channel 252 of the second channel system 72 , the second The two-liquid discharge channel 253, the liquid ejection port 254, and the liquid suction port 255 are arranged at positions separated from each other. A predetermined angle α between the two lines L1 and L2 is, for example, 30 degrees, but is not limited to this.

Details of the configurations of the first channel system 71 and the second channel system 72 will be described below. FIG. 7 is a cross-sectional view along line BB in FIG. 6 schematically showing one embodiment of the first flow path system 71 of the head nozzle 40. As shown in FIG. The film thickness measuring head 31 has respective ends of a light-projecting optical fiber cable 38 and a light-receiving optical fiber cable 39, and a fiber holder 41 for holding these ends. The head nozzle 40 has a shape that covers the tip of the film thickness measurement head 31 . The first channel system 71 of the head nozzle 40 has a fluid chamber 151 , a first liquid supply channel 152 , a first liquid discharge channel 153 and an opening 154 . The fluid chamber 151 is provided on the optical path of the light emitted from the film thickness measuring head 31 to the surface of the substrate W and the reflected light from the substrate W received by the film thickness measuring head 31 . A lower end 31 a of the film thickness measuring head 31 faces the fluid chamber 151 .

The first liquid supply channel 152 and the first liquid discharge channel 153 are connected to the fluid chamber 151 . The first liquid supply channel 152 is connected to the first liquid supply line 142 (see FIG. 1) at the first pipe connection portion 152b. The first liquid discharge channel 153 is connected to the first liquid discharge line 143 (see FIG. 1) at the second pipe connection portion 153c. A first connecting portion 152 a between the first liquid supply channel 152 and the fluid chamber 151 is positioned below a second connecting portion 153 a between the first liquid discharge channel 153 and the fluid chamber 151 . More specifically, the first connecting portion 152a between the first liquid supply channel 152 and the fluid chamber 151 is positioned below the fluid chamber 151, and the second connecting portion 152a between the first liquid discharge channel 153 and the fluid chamber 151 is located. The connecting portion 153 a is positioned above the fluid chamber 151 .

Since the first connecting portion 152a between the first liquid supply channel 152 and the fluid chamber 151 is positioned below the fluid chamber 151, the liquid that has flowed into the fluid chamber 151 from the first connecting portion 152a and the fluid chamber 151 have already Collision with the liquid existing in 151 is mitigated, and generation of air bubbles due to collision between liquids can be reduced. In addition, since the second connecting portion 153a between the first liquid discharge channel 153 and the fluid chamber 151 is located above the fluid chamber 151, the air bubbles generated in the fluid chamber 151 are discharged into the first liquid discharge channel. 153 can be quickly discharged.

The opening 154 is provided on the optical path of the light emitted from the film thickness measuring head 31 to the surface of the substrate W and the reflected light from the substrate W received by the film thickness measuring head 31 . The opening 154 communicates with the lower end of the fluid chamber 151 , and the width a 1 of the opening 154 is smaller than the width a 2 of the fluid chamber 151 . As a result, air bubbles generated in the fluid chamber 151 are dispersed above the fluid chamber 151 without remaining in the opening 154 . In one embodiment, the width a1 of opening 154 is in the range of 1.0 mm to 2.0 mm. This minimizes the flow rate of the liquid flowing out of the fluid chamber 151 through the opening 154 to prevent dilution of the polishing liquid on the substrate W, and to prevent the light emitted from the film thickness measurement head 31 and the substrate W from This is to ensure a path for reflected light.

The opening 154 is located in the bottom surface 40a of the head nozzle 40 and can be approached facing the surface of the substrate W for measuring the film thickness of the substrate W. As shown in FIG. 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 within the range of 0.5 mm to 1.0 mm. This is also to prevent dilution of the polishing liquid on the substrate W by minimizing the flow rate of the liquid flowing out from the fluid chamber 151 through the opening 154 .

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

The width a2 of the portion of the fluid chamber 151 where the first connecting portion 152a between the first liquid supply channel 152 and the fluid chamber 151 is located is the width of the portion of the fluid chamber 151 facing the lower end 31a of the film thickness measuring head 31. smaller than the width a3. As a result, bubbles generated in the fluid chamber 151 are dispersed outside the optical path without remaining on the optical path during film thickness measurement. The second connecting portion 153 a is located at the lower end of the film thickness measuring head 31 . More specifically, the upper surface 153 b of the first liquid discharge channel 153 extending from the second connecting portion 153 a is positioned higher than the lower end of the film thickness measuring head 31 . With this arrangement, bubbles are quickly discharged through the first liquid discharge channel 153 without remaining in the fluid chamber 151 .

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

The liquid supplied from the first liquid supply line 142 is pure water, for example. The liquid may be any transparent liquid, such as a KOH solution used as 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, the liquid is supplied to the substrate W, and the polishing liquid and the polishing dust present on the substrate W are removed. be. Since the optical path during film thickness measurement is filled with 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 always be open during polishing of the substrate W regardless of the position of the film thickness measurement head 31, or they may be opened only when the film thickness measurement head 31 is at the measurement position. may

In one embodiment, the flow rate of liquid flowing through the first liquid discharge channel 153 is in the range of 90% to 95% of the flow rate of liquid flowing through the first liquid supply channel 152, and from the opening 154 to the substrate W. The flow rate of the liquid supplied is within 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 deteriorating the polishing performance.

FIG. 8 is a cross-sectional view taken along line CC of FIG. 6 schematically showing one embodiment of the second channel system 72 of the head nozzle 40. As shown in FIG. FIG. 9 is a bottom view of the head nozzle 40 according to this embodiment. The second channel system 72 of the head nozzle 40 has a second liquid supply channel 252 , a second liquid discharge channel 253 , a liquid outlet 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 a third pipe connection portion 252a. The second liquid discharge channel 253 is connected to the second liquid discharge line 243 (see FIG. 1) at a fourth pipe connection portion 253a.

The liquid ejection port 254 communicates with the lower end of the second liquid supply channel 252 . The second liquid supply channel 252 bends at a bend 252 b and the lower portion of the second liquid supply channel 252 is inclined 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 is bent at a bend 253 b and the lower part of the second liquid discharge channel 253 is inclined 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 , the entirety of the second liquid supply channel 252 and the second liquid discharge channel 253 may be inclined toward the opening 154 of the first channel system 71 without the bends 252b and 253b. .

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

Both the liquid ejection port 254 and the liquid suction port 255 are larger than the opening 154 . Also, the liquid inlet 255 is larger than the liquid outlet 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 . A liquid outlet 254 is oppositely proximate to the surface of the substrate W for supplying liquid onto the surface of the substrate W. As shown in FIG. The liquid suction port 255 is capable of facing and approaching the surface of the substrate W for sucking liquid on the surface of the substrate W. As shown in FIG. In one embodiment, the distance c1 from the lower ends of the liquid ejection 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. is.

When the second supply valve 244 (see FIG. 1) is opened, the liquid flowing through the second liquid supply line 242 passes through the second liquid supply channel 252 and flows from the liquid discharge port 254 to the surface of the substrate W (the surface to be polished 2). ). When the second discharge valve 245 (see FIG. 1) is opened, the liquid on the surface of the substrate W (surface to be polished 2) is sucked into the liquid suction port 255, passes through the second liquid discharge channel 253, and flows into the second liquid. It flows through the second liquid discharge line 243 and is discharged out of 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 liquid supplied to the substrate W from the liquid outlet 254 is greater than the flow rate of liquid flowing through the opening 154 .

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

The liquid thus mixed 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 dust existing between the opening 154 and the substrate W are removed. Since the optical path between the opening 154 and the substrate W during film thickness measurement is filled with transparent liquid, the film thickness of the substrate W can be measured with high accuracy. In particular, according to this embodiment, since the liquid flow from the liquid ejection port 254 to 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 opening portion can be The optical path between 154 and substrate W can be filled with a clear liquid.

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

FIG. 10 is a flow chart illustrating an example of the process of measuring the film thickness of the substrate W. As shown in FIG.
In step S<b>101 , the stage 10 supports the substrate W with the surface 2 to be polished of the substrate W facing upward, and the stage rotation mechanism rotates the stage 10 .
In step S<b>102 , the polishing unit 20 starts polishing the substrate W while supplying the polishing liquid to the substrate W from the polishing liquid supply nozzle 28 .

In step S<b>103 , the polishing head moving mechanism 24 starts moving the polishing head 21 , and the film thickness measuring head moving mechanism 37 starts moving the film thickness measuring head 31 . At this time, the polishing head 21 and the film thickness measuring head 31 move so as not to contact each other.
In step S<b>104 , the first supply valve 144 and the first discharge valve 145 are opened to discharge the liquid from the liquid chamber 51 while supplying the liquid to the liquid chamber 51 of the head nozzle 40 . Further, the second supply valve 244 and the second discharge valve 245 are opened, and liquid supply from the head nozzle 40 is started.

In step S105, the film thickness measurement head 31 is moved to the measurement position, and the opening 154, the liquid ejection port 254, and the liquid suction port 255 of the head nozzle 40 are brought close to the surface of the substrate W. FIG. The liquid flows out through the opening 154 of the head nozzle 40 , is supplied to the substrate W from the liquid ejection port 254 , and is sucked from the substrate W through the liquid suction port 255 . A liquid flow is formed on the surface of the substrate W from the liquid ejection port 254 toward the liquid suction port 255 . The opening 154 faces this liquid flow, and the liquid flowing out from the opening 154 joins the liquid flowing from the liquid ejection port 254 to the liquid suction port 255 .

In step S<b>106 , the light source 32 emits light, and the surface of the substrate W is irradiated with the light from the film thickness measurement head 31 through the fluid chamber 151 and the opening 154 .
In step S<b>107 , the film thickness measurement head 31 receives reflected light from the substrate W through the fluid chamber 151 and the opening 154 . The light from the film thickness measuring head 31 and the reflected light from the substrate W flow through the liquid flowing in the fluid chamber 151 , the liquid flowing in the opening 154 , and the liquid discharging port 254 to the liquid suction port 255 . Since it passes through the liquid, a good optical path can be secured.
In step S<b>108 , 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 section 34 . The spectrum analysis unit 34 determines the film thickness of the substrate W by generating the spectrum of the reflected light from the intensity measurement data of the reflected light.

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 reaches 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 polishing the substrate W and repeats steps S105 to S109.

FIG. 11 is a cross-sectional view schematically showing another embodiment of the second channel system 72 of the head nozzle 40. As shown in FIG. FIG. 12 is a bottom view of the head nozzle 40 according to the embodiment shown in FIG. The second channel system 72 shown in FIG. 11 further comprises a liquid collection groove 257 . The liquid collecting groove 257 is positioned within the bottom surface 40 a 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 channel 253 via the liquid suction port 255 . A liquid collection groove 257 can be approached opposite the surface of the substrate W for collecting and draining liquid on the surface of the substrate W. As shown in FIG. 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 within the range of 0.3 mm to 5.0 mm.

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 rotation direction P of the substrate W. As shown in FIG. The liquid collecting groove 257 has a substantially elliptical shape when the head nozzle 40 is viewed from below. Width d2 of liquid collecting groove 257 is greater than width d3 of liquid suction port 255 . The width d2 of the liquid collecting groove 257 is the width in the direction substantially orthogonal to the rotation direction P of the substrate W, and the width d3 of the liquid suction port 255 is the width in the direction substantially orthogonal to the rotation direction P of the substrate W. width.

As indicated by the arrows in FIG. 12, the liquid supplied onto the surface of the substrate W from the liquid ejection port 254 flows along the rotation direction P of the substrate W, and when it spreads outward, it is recovered by the liquid collecting groove 257. and discharged through the second liquid discharge channel 253 . This is to prevent the polishing liquid on the substrate W from being diluted and deteriorating the polishing performance by collecting the liquid flowing out from the opening 154 and the liquid ejection port 254 in the liquid collecting groove 257 .

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. may be

The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiments can be made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in its broadest scope in accordance with the technical spirit defined by the claims.

1 substrate polishing apparatus 2 surface to be polished 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 measurement head 32 Light source 33 Spectrometer 34 Spectrum analysis section 34a Storage device 34b Processing device 36 Film thickness measurement head arm 37 Film thickness measurement head moving mechanism 38 Optical fiber cable for light projection 39 Optical fiber cable for light reception 40 Head nozzle 41 Fiber holder 60 Operation control unit 60a Storage device 60b Processing device 71 First channel system 72 Second channel system 142 First liquid supply line 143 First liquid discharge line 144 First supply valve 145 First discharge valves 146, 147 Flow meter 148 Liquid pump 151 Fluid chamber 152 First liquid supply channel 152a First connection part 152b First pipe connection part 153 First liquid discharge channel 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 valves 246, 247 Flowmeter 248 Liquid pump 252 Second liquid supply channel 252a Third pipe connection portion 252b Bent portion 253 Second liquid discharge channel 253a Fourth pipe connection portion 253b Bent portion 254 Liquid discharge port 255 Liquid suction port 257 Liquid collecting groove

Claims (16)

a stage that supports the substrate with the surface to be polished facing upward and rotates the substrate;
a polishing head holding a polishing pad having a polishing surface for polishing the substrate supported by the stage;
a polishing liquid supply nozzle that supplies a polishing liquid onto the surface of the substrate;
a film thickness measuring head that irradiates a measurement area on the surface of the substrate on the stage with light 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 comprises a first channel system and a second channel system that form a flow of liquid across optical paths of the light and the reflected light;
The first channel system has an opening located on the optical path,
The substrate polishing apparatus, wherein the second channel system has a liquid outlet and a liquid inlet, and the liquid outlet and the liquid inlet are positioned on both sides of the opening. 2. The substrate polishing apparatus according to claim 1, wherein said liquid discharge port and said liquid suction port are arranged symmetrically with respect to said opening. 3. The substrate polishing apparatus according to claim 1, wherein said opening, said liquid ejection port, and said liquid suction port are positioned within the bottom surface of said head nozzle. 4. The substrate polishing apparatus according to claim 1, wherein said liquid ejection port is located upstream of said opening and said liquid suction port in the rotation direction of said substrate. The first channel system is
a fluid chamber provided on the optical path;
a first liquid supply channel for supplying liquid to the fluid chamber;
a first liquid discharge channel for discharging liquid from the fluid chamber;
The opening communicates with the lower end of the fluid chamber and is accessible to the surface of the substrate,
The second channel system is
a second liquid supply channel for supplying liquid onto the surface of the substrate;
a second liquid discharge channel for discharging liquid on the surface of the substrate;
the liquid ejection port that communicates with the second liquid supply channel and is accessible to the surface of the substrate;
5. The substrate polishing apparatus according to any one of claims 1 to 4, further comprising said liquid suction port communicating with said second liquid discharge channel and being able to approach the surface of said substrate. 6. The substrate polishing apparatus according to claim 1, wherein both said liquid ejection port and said liquid suction port are larger than said opening. 7. The substrate polishing apparatus according to claim 1, wherein said liquid suction port is larger than said liquid discharge port. the second channel system further comprising a liquid collecting groove accessible to the surface of the substrate, connected to the liquid inlet;
the liquid collecting groove is located upstream of the liquid suction port in the rotation direction of the substrate,
8. The substrate polishing apparatus according to claim 1, wherein width of said liquid collecting groove is larger than width of said liquid suction port. rotating the substrate while supporting the substrate with the surface to be polished facing upward;
polishing the substrate by pressing a polishing pad having a polishing surface against the substrate with a polishing head while supplying a polishing liquid to the surface of the substrate;
supplying the liquid onto the surface of the substrate from a liquid ejection port provided in the head nozzle while flowing the liquid into an opening provided in the head nozzle adjacent to the surface of the substrate; irradiating a measurement region on the surface of the substrate with light from the film thickness measurement head through the opening while sucking the liquid of through the liquid suction port;
receiving reflected light from the measurement region through the opening with the film thickness measurement head;
determining the film thickness of the substrate from the spectrum of the reflected light;
The substrate polishing method, wherein the liquid discharge port and the liquid suction port are positioned on both sides of the opening. 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 the measurement region on the surface of the substrate from the film thickness measurement head through the opening includes: irradiating the measurement region on the surface of the substrate from the film thickness measurement head through the fluid chamber and the opening; A step of irradiating light on
The step of receiving the reflected light from the measurement region through the opening with the film thickness measurement head is a step of receiving the reflected light from the measurement region with the film thickness measurement head through the opening and the fluid chamber. 10. The substrate polishing method according to claim 9. 11. The substrate polishing method according to claim 9, wherein said liquid ejection port and said liquid suction port are arranged symmetrically with respect to said opening. 12. The substrate polishing method according to claim 9, wherein said opening, said liquid ejection port, and said liquid suction port are positioned within the bottom surface of said head nozzle. 13. The method of polishing a substrate according to claim 9, wherein said liquid ejection port is located upstream of said opening and said liquid suction port in the direction of rotation of said substrate. 14. The substrate polishing method according to claim 9, wherein both said liquid ejection port and said liquid suction port are larger than said opening. 15. The substrate polishing method according to claim 9, wherein said liquid suction port is larger than said liquid discharge port. The head nozzle has a liquid collection groove connected to the liquid suction port,
the liquid collecting groove is located upstream of the liquid suction port in the rotation direction of the substrate,
16. The substrate polishing method according to any one of claims 9 to 15, wherein the width of said liquid collecting groove is larger than the width of said liquid suction port.

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