POLISHING APPARATUS

Description

TECHNICAL FIELD

The present invention relates to a polishing apparatus.

BACKGROUND ART

A planarization technology of a surface of a device is becoming increasingly important in a manufacturing process of a semiconductor device. A most important planarization technology is a chemical mechanical polishing (CMP). In this chemical mechanical polishing (hereinafter referred to as a CMP), a polishing apparatus is used to polish a substrate such as a wafer by sliding it against a polishing surface while a polishing liquid (slurry) containing abrasive grains such as silica (SiO₂) or ceria (CeO₂) is supplied to a polishing pad.

A CMP (Chemical Mechanical Polishing) apparatus is used in a process of polishing the surface of the substrate in a manufacture of the semiconductor device. The CMP apparatus holds the substrate by a polishing head, rotates the substrate, and then presses the substrate against the polishing pad on the rotating polishing table to polish the surface of the substrate. During polishing the substrate, the polishing liquid (slurry) is supplied onto the polishing pad, and the surface of the substrate is planarized by a chemical action of the polishing liquid and a mechanical action of the abrasive grains in the polishing liquid.

CITATION LIST

Patent Literature

• • Patent document 1: Japanese laid-open patent publication No. 2020-110859
  • Patent document 2: Japanese laid-open patent publication No. 2019-84614

SUMMARY OF INVENTION

Technical Problem

A polishing rate of the substrate depends on a surface temperature of the substrate. Therefore, in the manufacture of the semiconductor device, it is important to manage the polishing rate of the substrate based on the surface temperature of the substrate. Instead of directly measuring the surface temperature of the substrate during polishing the substrate, it is known to measure a temperature of the polishing pad. In such a method, the surface temperature of the substrate is estimated based on the measured temperature of the polishing pad. However, in order to manage the polishing rate more accurately, it is desirable to directly measure the surface temperature of the substrate.

A configuration may be considered in which a temperature measurement device is provided on the polishing head that holds a back surface of the substrate. In such a configuration, the temperature measurement device measures a back-surface temperature of the substrate from the polishing head side. However, since the substrate has a thickness, temperature distributions on a front surface and the back surface of the substrate are different, and even if the temperature on the back surface of the substrate is measured, the surface temperature of the substrate cannot be accurately obtained. Furthermore, since electronic devices are processed on the front surface of the substrate, a type of a temperature measurement sensor that comes into contact with the front surface of the substrate cannot generally be used.

Therefore, the present invention provides a polishing apparatus that can accurately measure a surface temperature of a substrate.

Solution to Problem

In an embodiment, there is provided a polishing apparatus comprising: a plurality of window members configured to transmit an infrared radiation; a polishing pad in which the window members are embedded; a polishing table configured to support the polishing pad and rotate together with the polishing pad; a polishing head configured to rotatably hold a substrate and press the substrate against the polishing pad; and a plurality of infrared radiation thermometers arranged below the window members and configured to measure a surface temperature of the substrate held by the polishing head.

In an embodiment, the infrared radiation thermometers are arranged in a radial direction of the polishing table and rotate together with the polishing table.

In an embodiment, each of the infrared radiation thermometers comprises a shutter having a black body structure configured to open and close a light receiving portion of each of the infrared radiation thermometers.

In an embodiment, each of the infrared radiation thermometers is a radiation thermometer with a capability to measure a temperature of an object to be measured, which has low emissivity, by suppressing effects of external disturbances.

In an embodiment, there is provided a polishing apparatus comprising: a window member configured to transmit an infrared radiation; a polishing pad in which the window member is embedded; a polishing table configured to support the polishing pad and rotate together with the polishing pad; a polishing head configured to rotatably hold a substrate and press the substrate against the polishing pad; and an infrared radiation thermometer arranged below the polishing table and configured to measure a surface temperature of the substrate held by the polishing head, the infrared radiation thermometer comprises a plurality of light receiving portions arranged along a rotation locus of the window member.

In an embodiment, the polishing table comprises a black body fixed to a lower surface of the polishing table, and the black body is arranged at a position corresponding to the rotation locus of the window member.

In an embodiment, the polishing apparatus comprises a liquid removal mechanism configured to remove a liquid from a light path of an infrared radiation transmitted through the window member.

In an embodiment, the liquid removal mechanism comprises an elastic ring surrounding the window member, and the elastic ring protrudes from a polishing surface of the polishing pad.

In an embodiment, the liquid removal mechanism comprises: a gas injection device configured to inject a gas across the light path; and a liquid collection member configured to collect the liquid blown out of the light path by the gas injection device.

In an embodiment, the infrared radiation thermometer is a radiation thermometer with a capability to measure a temperature of an object to be measured, which has low emissivity, by suppressing effects of external disturbances.

In an embodiment, there is provided a polishing apparatus comprising: a polishing pad; a polishing table configured to support the polishing pad and rotate together with the polishing pad; a polishing head configured to rotatably hold a substrate and press the substrate against the polishing pad; a first temperature measurement device configured to measure a surface temperature of a first region of the substrate; and a second temperature measurement device configured to measure the surface temperature of a second region having a larger temperature distribution than the first region, the first temperature measurement device comprises: a plurality of first window members configured to transmit an infrared radiation and embedded in the polishing pad; and a plurality of first infrared radiation thermometers arranged below the first window members, and the second temperature measuring device comprises: a second window member configured to transmit an infrared radiation and embedded in the polishing pad; and a second infrared radiation thermometer arranged below the polishing table and comprising a plurality of light receiving portions arranged along a rotation locus of the second window member.

Advantageous Effects of Invention

According to the invention, the surface temperature of the substrate can be accurately measured, without contact, during polishing the substrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing one embodiment of a polishing apparatus;

FIG. 2 is a cross sectional view of the polishing apparatus shown in FIG. 1;

FIG. 3 is an enlarged view of a window member and an infrared radiation thermometer;

FIG. 4 is a view showing a plurality of infrared radiation thermometers arranged in a radial direction of a polishing table;

FIG. 5 is a view showing a graph showing a surface temperature of a substrate measured by a plurality of infrared radiation thermometers, and a graph showing a temperature distribution in the radial direction of the substrate;

FIG. 6 is a view showing another embodiment of the infrared radiation thermometer;

FIG. 7 is a cross sectional view showing another embodiment of the polishing apparatus;

FIG. 8 is an enlarged view of the window member and the infrared radiation thermometer;

FIG. 9 is a view showing the infrared radiation thermometer according to the embodiment shown in FIGS. 7 and 8;

FIG. 10 is a graph showing the temperature distribution in the radial direction of the substrate;

FIG. 11A is a view showing a black body portion fixed to a lower surface of the polishing table;

FIG. 11B is a view showing the black body portion fixed to the lower surface of the polishing table;

FIG. 12A is a view showing an embodiment of a liquid removal mechanism that removes a liquid from a light path of the infrared radiation transmitted through the window member;

FIG. 12B is a view showing an embodiment of the liquid removal mechanism that removes the liquid from the light path of the infrared radiation transmitted through the window member;

FIG. 13A is a view showing another embodiment of the liquid removal mechanism; and

FIG. 13B is a view showing another embodiment of the liquid removal mechanism.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below with reference to the drawings. In the drawings described below, identical or equivalent components will be marked with the same symbol and redundant explanations will be omitted.

FIG. 1 is a perspective view showing one embodiment of a polishing apparatus. As shown in FIG. 1, a polishing apparatus (CMP apparatus) includes a polishing table 2 that supports a polishing pad 1 and rotates together with the polishing pad 1, a polishing head 3 that presses a substrate W such as a wafer to be polished against the polishing pad 1, and a polishing liquid supply mechanism 4 for supplying a polishing liquid (slurry) onto the polishing pad 1.

The polishing table 2 is coupled to a table motor 6 arranged below a table shaft 5 via the table shaft 5, and the table motor 6 rotates the polishing table 2 in a direction shown by an arrow. The polishing pad 1 is attached to an upper surface of the polishing table 2, and an upper surface of the polishing pad 1 constitutes a polishing surface 1a for polishing the substrate W. The polishing head 3 is fixed to a lower end of the head shaft 7. The polishing head 3 is configured to be able to hold the substrate W on a lower surface of the polishing head 3 by vacuum suction. More specifically, the polishing head 3 holds a surface (device surface) of the substrate W facing downward. A surface opposite to the surface is a back surface of the substrate W, and the polishing head 3 holds the back surface of the substrate W by suction.

The head shaft 7 is coupled to a rotation mechanism, not shown, installed in a head arm 8, and the polishing head 3 is driven rotationally via the head shaft 7 by this rotation mechanism.

The polishing apparatus further includes a dressing device 24 for dressing the polishing pad 1. The dressing device 24 includes a dresser 26 that comes into sliding contact with the polishing surface 1a of the polishing pad 1, a dresser arm 27 that supports the dresser 26, and a dresser swivel shaft 28 that swivels the dresser arm 27. As the dresser arm 27 swivels, the dresser 26 oscillates on the polishing surface 1a. A lower surface of the dresser 26 constitutes a dressing surface consisting of a number of abrasive grains such as diamond particles. The dresser 26 rotates while oscillating over the polishing surface 1a and dresses the polishing surface 1a by slightly scraping the polishing pad 1. During dressing the polishing pad 1, pure water is supplied from a pure water supply nozzle 25 onto the polishing surface 1a of the polishing pad 1.

The polishing liquid supply mechanism 4 includes a slurry supply nozzle 10 for supplying the polishing liquid onto the polishing pad 1, and a nozzle swivel shaft 11 to which the slurry supply nozzle 10 is fixed. The slurry supply nozzle 10 is configured to be able to swivel around the nozzle swivel shaft 11.

The substrate W is rotatably held by the polishing head 3. The polishing head 3 presses the substrate W against the polishing pad 1, and a polishing of the substrate W progresses by sliding between the polishing pad 1 and the substrate W. When polishing the substrate W, the polishing liquid (slurry) is supplied from the slurry supply nozzle 10 onto the polishing pad 1.

The polishing apparatus has a configuration that directly measures a surface temperature of the substrate W (i.e., a temperature on the device surface side) without contacting the substrate W during polishing the substrate W. Hereinafter, such a configuration will be explained with reference to the drawings.

As shown in FIG. 1, the polishing apparatus includes a plurality of window members 50A to 50E embedded in the polishing pad 1, and a plurality of infrared radiation thermometers 51A to 51E arranged below the window members 50A to 50E and measure the surface temperature of the substrate W held by the polishing head 3. Since the window members 50A to 50E have the same configuration, the window members 50A to 50E may hereinafter be referred to collectively as a window member 50. Similarly, since the infrared radiation thermometers 51A to 51E have the same configuration, the infrared radiation thermometers 51A to 51E may hereinafter be referred to collectively as an infrared radiation thermometers 51.

FIG. 2 is a cross sectional view of the polishing apparatus shown in FIG. 1. In FIG. 2, illustrations other than the main elements of the polishing apparatus are omitted. As shown in FIG. 2, a window hole 1b, having a size that allows the window member 50 to be inserted therein, is formed in the polishing pad 1. The window member 50 is inserted into the window hole 1b. The window hole 1b is a through hole that penetrates the polishing pad 1 in a vertical direction.

The window member 50 is made of a material that transmits an infrared radiation. The infrared radiation thermometer 51 is arranged directly below the window member 50. The infrared radiation thermometer 51 is a thermometer that measures the surface temperature of the substrate W based on an intensity of the infrared radiation emitted from the substrate W.

An embedded portion 52 communicating with the window hole 1b is formed in the polishing table 2, and the infrared radiation thermometer 51 is arranged in the embedded portion 52. In the embodiment shown in FIG. 2, the infrared radiation thermometer 51 is arranged so as to be embedded in the polishing table 2. Although not shown in the drawing, the polishing table 2 has the number (in this embodiment, five) of embedded portions 52 corresponding to the number of infrared radiation thermometers 51A to 51E.

FIG. 3 is an enlarged view of the window member and the infrared radiation thermometer. As shown in FIG. 3, the window member 50 has a front surface 50a facing the polishing head 3 and a back surface 50b facing the polishing table 2. The front surface 50a of the window member 50 is an exposed surface exposed from the polishing surface 1a of the polishing pad 1. The front surface 50a of the window member 50 and the polishing surface 1a of the polishing pad 1 are arranged in the same plane.

A space S1 in which no obstacles exist is formed between the back surface 50b of the window member 50 arranged on the polishing pad 1 and a light receiving portion 51a of the infrared radiation thermometer 51. In other words, the space S1 is a space for reliable measuring the surface temperature of the substrate W by the infrared radiation thermometer 51.

The substrate W is generally made of silicon. Silicon (Si) absorbs light in a range of 1.5 to 6.0 micrometer. Therefore, the infrared radiation in the same region is negligible. In this embodiment, since the infrared radiation thermometer is used that non-contactly measures a temperature of a radiator based on the amount of infrared radiations emitted, it is not desirable to measure a wavelength band with a little infrared radiation.

Therefore, an infrared radiation thermometer using an infrared radiation absorbing film suitable for measuring the amount of infrared radiations with a wavelength of 1.5 micrometers or less or 6.0 micrometers or more is used. The wavelength range of the measured amount of infrared radiation is 0.8 to 1.5 micrometers, or 6.0 to 1000 micrometers.

An infrared radiation thermometer using indium compounds such as InGaAs, InAs, InAsSb, and InSb as the infrared radiation absorbing films is considered desirable, but there is no need to limit a material as long as an infrared radiation absorbing film with sufficient sensitivity in the wavelength region to be measured above is used.

The window member 50 installed on the polishing pad 1 needs to be made of a material that transmits the infrared radiation of the wavelength to be measured. Materials that transmit the above wavelengths include an infrared radiation transmitting resin, calcium fluoride, synthetic quartz, germanium, magnesium fluoride, optical glass (N-BK7), potassium bromide, sapphire, silicon, sodium chloride, zinc selenium, or zinc sulfide. However, as long as the above conditions are met, there is no need to limit the material.

In this manner, by selecting the materials of the window member 50 and the infrared radiation absorbing film, the infrared radiation emitted from the substrate W made of silicon can pass through the window member 50 without being attenuated (or with sufficiently low attenuation), and the amount of infrared radiation can be measured by the infrared radiation thermometer 51. As a result, it becomes possible to measure the surface temperature of the substrate W.

A metal (conductor) film or an insulating film may be formed on the surface of the substrate W made of silicon. Therefore, in one embodiment, the materials of the window member 50 and the infrared radiation absorbing film may be selected depending on a wavelength dependence of an emissivity of the material constituting the metal film or the insulating film.

The window member 50 contacts the substrate W to be polished. Therefore, it is more desirable to construct the window member 50 from a material that has similar mechanical, thermal, and chemical properties to the polishing pad 1 as much as possible.

As shown in FIG. 1, the polishing apparatus has a capability to record or display the measured temperature distribution. More specifically, the polishing apparatus includes a storage device 101 that records the measured temperature distribution of the substrate W on a storage element such as HDD or SSD, and a display device 102 that can display on a screen the temperature distribution in a direction of a diameter of the substrate W through a center of the substrate W. In this embodiment, the storage device 101 and the display device 102 constitute a control device 100.

As shown in FIG. 1, the control device 100 is electrically connected to the infrared radiation thermometers 51A to 51E. Although not shown in the drawing, the control device 100 is connected to components (e.g., the polishing head 3, the polishing liquid supply mechanism 4, the table motor 6, and the dressing device 24) of the polishing apparatus to control operations of the above components. The controller 100 may control the operations of the components of the polishing apparatus and manage a polishing rate based on the temperature distribution of the substrate W stored in the storage device 101.

FIG. 4 is a view showing a plurality of infrared radiation thermometers arranged in a radial direction of the polishing table. As shown in FIG. 4, the infrared radiation thermometers 51A to 51E are arranged in the radial direction of the polishing table 2 and rotate together with the polishing table 2. During polishing the substrate W, the infrared radiation thermometers 51A to 51E cross the surface of the substrate W every time the polishing table 2 rotates once. In the embodiment shown in FIG. 4, the infrared radiation thermometer 51C is arranged so that its rotation locus passes over a center CP of the substrate W. In one embodiment, the infrared radiation thermometer 51C does not necessarily have to be arranged so that its rotation locus passes over the center CP of the substrate W.

Each of these infrared radiation thermometers 51A to 51E draws different trajectories on the substrate W and measures the entire surface temperature of the substrate W in the radial direction at a plurality of different measurement points. Therefore, even if each of the infrared radiation thermometers 51A to 51E does not have a sufficient temperature measurement frequency, the temperature distribution on the surface of the substrate W can be measured with sufficient spatial resolution.

FIG. 5 is a view showing a graph showing the surface temperature of the substrate measured by a plurality of infrared radiation thermometers, and a graph showing the temperature distribution in the radial direction of the substrate. In the graph shown in an upper side of FIG. 5, a horizontal axis represents time, and a vertical axis represents the surface temperature of the substrate W. In the graph shown in a bottom side of FIG. 5, a horizontal axis represents a distance in the radial direction of the substrate W, and a vertical axis represents the surface temperature of the substrate W.

As shown in the upper graph of FIG. 5, the infrared radiation thermometers 51A to 51E measure the surface temperature of the substrate W for a certain period of time. The control device 100 arranges the surface temperature of the substrate W, which changes over time, measured by the infrared radiation thermometers 51A to 51E, into the temperature distribution in the radial direction of the substrate W. More specifically, the control device 100 superimposes the respective trajectories of the infrared radiation thermometers 51A to 51E passing over the surface of the substrate W to form one trajectory in the radial direction of the substrate W. The control device 100 arranges the surface temperatures of the substrate W measured by each of the infrared radiation thermometers 51A to 51E on one trajectory formed. In this manner, according to the present embodiment, since the polishing apparatus includes the infrared radiation thermometers 51A to 51E, the entire surface temperature of the substrate W can be measured accurately (i.e., with high precision) in a non-contact manner.

FIG. 6 is a view showing another embodiment of the infrared radiation thermometer. As shown in FIG. 6, each of the infrared radiation thermometers 51A to 51E includes a shutter 161 having a black body structure, which opens and closes the light receiving portion 51a.

The shutter 161 having the black body structure is arranged to calibrate (more specifically, temperature calibrate) the infrared radiation thermometer 51. The infrared radiation thermometer 51 may be affected by an ambient temperature, etc., and as a result, the temperature measured by the infrared radiation thermometer 51 may deviate. Therefore, in the embodiment shown in FIG. 6, the infrared radiation thermometer 51 is calibrated using the black body structure with an emissivity of 1. As an example of the black body structure, a black-body tape may be attached to the shutter 161, or a black body may be applied to the shutter 161 using a black-body spray.

The shutter 161 is configured to open and close the light receiving portion 51a of the infrared radiation thermometer 51. Therefore, if necessary, the shutter 161 can be closed to calibrate the infrared radiation thermometer 51.

In one embodiment, the infrared radiation thermometer 51 may be calibrated periodically. For example, the shutter 161 may be closed and the infrared radiation thermometer 51 may be calibrated after processing a predetermined number of substrates W, or the infrared radiation thermometer 51 may be calibrated during idling (i.e., non-processing time of the substrate W) of the polishing apparatus.

When calibrating the infrared radiation thermometer 51, the temperature of the shutter 161 is measured by a reference thermometer (e.g., a thermocouple), and the temperature of the shutter 161 is measured by the infrared radiation thermometer 51 to be calibrated. Thereafter, the temperature of the shutter 161 measured by the reference thermometer is associated with the temperature measured by the infrared radiation thermometer 51 to be calibrated. Since it is known that the emissivity of the shutter 161 is 1, the infrared radiation thermometer 51 is calibrated based on a correlation between the temperature measured by the shutter 161 and the temperature measured by the infrared radiation thermometer 51.

In one embodiment, each of the infrared radiation thermometers 51A to 51E may be a radiation thermometer for metals or a radiation thermometer for mirror surfaces. More specifically, each of the infrared radiation thermometers 51A to 51E may be a radiation thermometer with a capability to accurately measure the temperature of an object to be measured, which generally has low emissivity, by suppressing the effects of external disturbances. With such a configuration, the surface temperature of the substrate W can be measured with higher accuracy based on the intensity of the infrared radiation emitted from the substrate W, which is a low emissivity material.

In the embodiment described above, the infrared radiation thermometers 51A to 51E are embedded in the polishing table 2, but in the embodiment shown below, the polishing apparatus includes a single infrared radiation thermometer 151 arranged below the polishing table 2.

FIG. 7 is a cross sectional view showing another embodiment of the polishing apparatus. FIG. 8 is an enlarged view of the window member and the infrared radiation thermometer. In this embodiment, the same structure as in the embodiment described above is indicated with the same symbol and detailed explanation is omitted.

As shown in FIGS. 7 and 8, the polishing apparatus includes a single window member 50 and the infrared radiation thermometer 151 arranged below the polishing table 2. In the embodiment shown in FIGS. 7 and 8, the polishing table 2 does not have the embedded portion 52 (see FIGS. 2 and 3).

FIG. 9 is a view showing the infrared radiation thermometer according to the embodiment shown in FIGS. 7 and 8. As shown in FIG. 9, the infrared radiation thermometer 151 has a different structure from the infrared radiation thermometer 51 described above. More specifically, the infrared radiation thermometer 151 is arranged to cover the entire measurement range of the substrate W.

In one embodiment, the infrared radiation thermometer 151 may be a radiation thermometer for metals or a radiation thermometer for mirror surfaces. More specifically, the infrared radiation thermometer 151 may be a radiation thermometer with the capability to accurately measure the temperature of an object to be measured, which generally has low emissivity, by suppressing the effects of external disturbances.

The infrared radiation thermometer 151 includes a plurality of light receiving portions 151a arranged in an arc along the rotation locus of the window member 50. These light receiving portions 151a are arranged over the entire substrate W. The window member 50 embedded in the polishing pad 1 rotates with the polishing table 2, but the infrared radiation thermometer 151 arranged below the polishing table 2 does not rotate with the table 2. Therefore, as the window member 50 passes directly under the substrate W, the plurality of light receiving portions 51a of the infrared radiation thermometer 151 continuously receive the infrared radiation emitted from the substrate W through the window member 50.

FIG. 10 is a graph showing a temperature distribution in the radial direction of the substrate. As shown in FIG. 10, the infrared radiation thermometer 151 is configured to measure the surface temperature at measurement points in the radial direction of the substrate W each time the polishing table 2 makes one rotation. In the embodiment shown in FIG. 10, the light receiving portions 151a of the infrared radiation thermometer 151 are arranged over the entire substrate W, so that the entire surface temperature in the radial direction of the substrate W can be measured each time the polishing table 2 makes one rotation.

In one embodiment, the first embodiment shown in FIGS. 1 to 6 and the second embodiment shown in FIGS. 7 to 10 may be combined. A combination of the window member 50 and the infrared radiation thermometer 51 according to the first embodiment corresponds to the first temperature measurement device. A combination of the window member 50 and the infrared radiation thermometer 151 according to the second embodiment corresponds to the second temperature measurement device. The polishing apparatus may include these first and second temperature measurement devices.

If a region of the substrate W is divided into a first region and a second region having a larger temperature distribution than the first region, the first temperature measurement device (i.e., the combination of the window member 50 and the infrared radiation thermometer 51) may measure the surface temperature of the first region of the substrate W. The second temperature measurement device (i.e., the combination of the window member 50 and the infrared radiation thermometer 151) may measure the surface temperature of the second region. For example, the second region is a periphery of the substrate W and the first region is a region inside the periphery of the substrate W.

When a liquid (e.g., pure water, polishing liquid) is supplied onto the polishing surface 1a of the polishing pad 1, the liquid contacts the periphery of the substrate W before the temperature rises, and then contacts the center side of the substrate W. In this manner, the liquid first contacts the periphery of the substrate W, resulting in a larger temperature distribution on the periphery of the substrate W. Since the infrared radiation thermometer 151 as a component of the second temperature measurement device is arranged at the periphery of the substrate W, the infrared radiation thermometer 151 can reliably measure the surface temperature of the periphery of the substrate W each time the polishing table 2 makes one rotation.

In this manner, by combining the first temperature measurement device that measures the first region of the substrate W and the second temperature measurement device that measures the second region of the substrate W, the polishing apparatus can measure the surface temperature of the substrate W with greater accuracy.

FIGS. 11A and 11B are views showing a black body portion fixed to a lower surface of the polishing table. As shown in FIGS. 11A and 11B, the polishing table 2 includes a black body 160 fixed to the lower surface (i.e., a surface facing the infrared radiation thermometer 151) of the polishing table 2. The black body 160 may be a fixed object to which the black-body tape is attached or a fixed object to which the black-body spray is applied.

As shown in FIGS. 11A and 11B, the black body 160 is arranged at a position corresponding to the rotation locus of the window member 50 (see FIG. 9). With this arrangement, the black body 160 passes above the infrared radiation thermometer 151 as the polishing table 2 rotates.

When calibrating the infrared radiation thermometer 151, the polishing apparatus rotates the polishing table 2 so that the black body 160 is arranged directly above the light receiving portion 151a of the infrared radiation thermometer 151. When the black body 160 is arranged directly above the light receiving portion 151a of the infrared radiation thermometer 151, a rotation of the polishing table 2 is stopped and the infrared radiation thermometer 151 is calibrated.

In one embodiment, the infrared radiation thermometer 151 may have a structure similar to the shutter 161 (see FIG. 6) described above, covering the light receiving portion 151a of the infrared radiation thermometer 151.

FIGS. 12A and 12B are views showing an embodiment of a liquid removal mechanism that removes a liquid from a light path of the infrared radiation transmitted through the window member. As shown in FIGS. 12A and 12B, the polishing apparatus includes a liquid removal mechanism 170 that removes the liquid from the light path (i.e., space S1) of the infrared radiation that is transmitted through the window member 50.

The liquid removal mechanism 170 includes an elastic ring 171 surrounding the window member 50. The elastic ring 171 protrudes from the polishing surface 1a of the polishing pad 1 and prevents the liquid flowing on the polishing surface 1a from entering the space S1. Since the elastic ring 171 is made of an elastic member such as rubber, even if the polishing head 3 comes into contact with the elastic ring 171, damage to the polishing head 3 (and/or the elastic ring 171) is prevented.

The liquid may pass through the window member 50 and enter onto the light path of the infrared radiation. If the liquid is present on the light path of the infrared radiation, the infrared radiation thermometer 51 (and infrared radiation thermometer 151) may not be able to accurately measure the surface temperature of the substrate W. Since the polishing apparatus includes the liquid removal mechanism 170, the infrared radiation thermometer 51 (and the infrared radiation thermometer 151) can accurately measure the surface temperature of the substrate W.

FIGS. 13A and 13B are views showing other embodiments of the liquid removal mechanism. In these embodiments, the liquid removal mechanism 170 includes a gas injection device 180 that injects a gas across the light path of the infrared radiation, and a liquid collection member 190 that collects the liquid blown out of the light path by the gas injection device 180.

As shown in FIG. 13A, the gas injection device 180 includes an injection nozzle 184 connected to the space S1, a gas supply line 181 connected to the injection nozzle 184, an on-off valve 182 that opens and closes the gas supply line 181, and a gas supply source 183 that supplies a high-pressure gas to the injection nozzle 184 through the gas supply line 181. Although not shown, the on-off valve 182 is electrically connected to the control device 100.

During polishing the substrate W, the high-pressure gas is continuously supplied from the gas supply source 183 to the injection nozzle 184 with the on-off valve 182 opens. The injection nozzle 184 injects the gas across the space S1, so the liquid that has entered the space S1 is vigorously blown out of the space S1 and collected by the liquid collection member 190.

As shown in FIG. 13B, the injection nozzle 184 is configured to form a curtain-like jet stream of gas throughout the space S1. In one embodiment, the injection nozzle 184 is fan-shaped nozzle. In one embodiment, the gas injection device 180 may include a plurality of injection nozzles 184. This configuration also allows the gas injection device 180 to form a curtain-like jet stream of the gas throughout the space S1.

The liquid collection member 190 is arranged on an opposite side of the injection nozzle 184 so as to collect the liquid blown by the injection nozzle 184. As shown in FIG. 13B, the liquid collection member 190 may be arranged to surround the space S1.

In one embodiment, the liquid removal mechanism 170 may include a combination of the elastic ring 171, the gas injection device 180, and the liquid collection member 190. This configuration allows the liquid removal mechanism 170 to more reliably remove the liquid that have entered the light path of the infrared radiation.

The above embodiments are described for the purpose of practicing the present invention by a person with ordinary skill in the art to which the invention pertains. Although preferred embodiments have been described in detail above, it should be understood that the present invention is not limited to the illustrated embodiments, but many changes and modifications can be made therein without departing from the appended claims.

INDUSTRIAL APPLICABILITY

The invention is applicable to a polishing apparatus.

REFERENCE SIGNS LIST

• • 1 polishing pad
  • 1a polishing surface
  • 1b window portion
  • 2 polishing table
  • 3 polishing head
  • 4 polishing liquid supply mechanism
  • 5 table shaft
  • 6 table motor
  • 7 head shaft
  • 8 head arm
  • 10 slurry supply nozzle
  • 11 nozzle swivel shaft
  • 24 dressing device
  • 25 pure water supply nozzle
  • 26 dresser
  • 27 dresser arm
  • 28 dresser swivel shaft
  • 50A˜50E window member
  • 50a front surface
  • 50b back surface
  • 51A˜51E infrared radiation thermometer
  • 51a light receiving portion
  • 52 embedded portion
  • 100 control device
  • 101 storage device
  • 102 display device
  • 151 infrared radiation thermometer
  • 151a light receiving portion
  • 160 black body
  • 161 shutter
  • 170 liquid removal mechanism
  • 171 elastic ring
  • 180 gas injection device
  • 181 gas supply line
  • 182 on-off valve
  • 183 gas supply source
  • 184 injection nozzle
  • 190 liquid collection member