System and method for measuring temperature

Abstract

To provide a technique capable of reducing a calculation cost when measuring a temperature of an object by using light.SOLUTION: A system for measuring a temperature includes a light source configured to emit broadband light, a sensor head including a lens having chromatic aberration, configured to irradiate an object with the broadband light generated by the light source through the lens, and configured to receive return light from a back surface of the object, a wavelength acquisition unit configured to receive the return light from the sensor head and acquire a peak wavelength of the return light, and a control unit configured to output the temperature of the object based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the object and the peak wavelength of the return light acquired by the sensor head.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] SUMMARY OF THE DISCLOSURE Exemplary embodiments of the present disclosure relate to a system for measuring temperature and a method for measuring temperature. [Background technology]

[0002] Patent Document 1 discloses a temperature measurement system that uses optical interference. The temperature measurement system emits output light including a first wavelength region and a second wavelength region to an object, and receives return light from the front and back surfaces of the object. The temperature measurement system performs a Fourier transform on the intensity distribution of the return light and calculates an optical path length ratio, which is the ratio between a first optical path length, which is the optical path length related to the output light in the first wavelength region, and a second optical path length, which is the optical path length related to the output light in the second wavelength region. The temperature measurement system calculates the temperature of the object based on a previously acquired relationship between the refractive index ratio and the temperature of the object, and the optical path length ratio. The refractive index ratio is the ratio between a first refractive index, which is the refractive index of the object related to the output light in the first wavelength region, and a second refractive index, which is the refractive index of the object related to the output light in the second wavelength region. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-060276 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can reduce the computational cost when measuring the temperature of an object using light. [Means for solving the problem]

[0005] One aspect of the present disclosure is a system for measuring temperature. The system includes a light source, a sensor head, a wavelength acquisition unit, and a control unit. The light source emits broadband light. The sensor head includes a lens with chromatic aberration and is configured to irradiate an object with the broadband light generated by the light source through the lens, and is also configured to receive return light from the back surface of the object. The wavelength acquisition unit is configured to receive the return light from the sensor head and acquire a peak wavelength of the return light. The control unit is configured to output the temperature of the object based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the object and the peak wavelength of the return light acquired by the sensor head. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to reduce the computational cost when measuring the temperature of an object using light. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a temperature measurement system according to an exemplary embodiment. [Figure 2] Fig. 2A is a schematic diagram showing an example of a light ray image of the sensor head when the temperature T of the object is temperature T1, and Fig. 2B is a schematic diagram showing an example of a light ray image of the sensor head when the temperature T of the object is temperature T2. [Figure 3] FIG. 3A shows an example of the relationship between the light intensity and wavelength of the measurement light, and FIG. 3B shows an example of the relationship between the light intensity and wavelength of the return light. [Figure 4] FIG. 4 is a table showing an example of the relationship between the peak wavelength and the temperature. [Figure 5] FIG. 5 is a flow chart of a method for using the temperature measurement system. [Figure 6] FIG. 6 is a diagram schematically illustrating an example of a substrate processing apparatus according to an exemplary embodiment. [Figure 7]Fig. 7A is a schematic diagram showing an example of a light ray image of the sensor head when the lens temperature T is temperature T3, and Fig. 7B is a schematic diagram showing an example of a light ray image of the sensor head when the lens temperature T is temperature T4. [Figure 8] FIG. 8 is a diagram illustrating an example of a temperature measurement system according to another exemplary embodiment. [Figure 9] FIG. 9(A) is a schematic diagram showing an example of the configuration of the temperature sensor section, and FIG. 9(B) is a schematic diagram showing another example of the configuration of the temperature sensor section. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various exemplary embodiments are described below.

[0009] Thermometers that measure temperature electrically or optically are known. Thermometers that measure temperature electrically include, for example, thermocouples or platinum resistance thermometers. Thermometers that measure temperature optically include, for example, infrared temperature sensors or fluorescent thermometers. Thermometers that measure temperature electrically have high noise levels in an environment where high frequency waves are applied (RF environment), such as in a substrate processing apparatus, making it difficult to measure the correct temperature.

[0010] Although thermometers that measure temperature optically can measure temperature appropriately even in an RF environment, they have other issues. For example, when an infrared temperature sensor measures the temperature of a material that transmits infrared rays (such as a silicon material), the infrared rays may penetrate the material and irradiate other materials. This limits the objects that can be measured depending on whether or not the infrared rays can penetrate. Fluorescent thermometers have fewer limitations on what can be measured, but they have the issue that the measurement cycle cannot be shortened to less than the fluorescence lifetime because they must measure the fluorescence lifetime.

[0011] The present disclosure provides a technology that can reduce the computational cost when measuring the temperature of an object using light. Computational cost refers to the amount of computation required, the number of tasks, complexity, etc. Furthermore, the present disclosure provides a technology that can detect temperature faster than a fluorescent thermometer while relaxing the limitations on the object being measured compared to an infrared temperature sensor.

[0012] One aspect of the present disclosure is a system for measuring temperature. The system includes a light source, a sensor head, a wavelength acquisition unit, and a control unit. The light source emits broadband light. The sensor head includes a lens with chromatic aberration and is configured to irradiate an object with the broadband light generated by the light source through the lens, and is also configured to receive return light from the back surface of the object. The wavelength acquisition unit is configured to receive the return light from the sensor head and acquire a peak wavelength of the return light. The control unit is configured to output the temperature of the object based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the object and the peak wavelength of the return light acquired by the sensor head.

[0013] In this system, broadband light generated by a light source is irradiated onto an object through a lens in a sensor head. Return light from the back surface of the object enters the sensor head and then enters a wavelength acquisition unit. The wavelength acquisition unit acquires the peak wavelength of the return light. The temperature of the object is then output based on a previously acquired relationship between the peak wavelength of the return light and the object temperature and the peak wavelength of the return light acquired by the sensor head. If the object is made of a material that has low absorption in the broadband light wavelength range and a temperature-dependent refractive index, changes in the distance to the back surface of the object are correlated with changes in the object's temperature. Because the intensity of the return light is highest for light with a wavelength focused on the back surface of the object, the distance to the back surface of the object depends on the peak wavelength of the return light. By acquiring the relationship between the peak wavelength of the return light and the object temperature in advance, this system can directly convert the measured peak wavelength into the object's temperature. Therefore, this system eliminates the need for Fourier transforms of the intensity distribution of the return light or calculating the optical path length ratio, as in conventional methods, thereby reducing computational costs. This system can measure the temperature of any object made of a material that has low absorption in the broadband light wavelength range and has a temperature-dependent refractive index. Therefore, this system has fewer limitations on the object it can measure than an infrared temperature sensor. Furthermore, because this system does not need to wait for the fluorescence lifetime to expire, it can detect temperature faster than a fluorescent thermometer.

[0014] In one embodiment, the control unit may calculate a correction value for correcting a change in peak wavelength due to a change in lens temperature based on the light returned from the surface of the object, and may correct the peak wavelength of the returned light using the correction value. This configuration allows the peak wavelength of the returned light to be corrected to a more appropriate value even if the focal length of the lens changes due to a change in lens temperature. Therefore, this system can more accurately measure the temperature of the object.

[0015] Another aspect of the present disclosure is a system for measuring temperature. The system includes a light source, a temperature sensor unit, a wavelength acquisition unit, and a control unit. The light source emits broadband light. The temperature sensor unit is configured to be in thermal contact with an object and generates return light using the broadband light generated by the light source. The wavelength acquisition unit is configured to receive the return light from the temperature sensor unit and acquire a peak wavelength of the return light. The control unit is connected to the temperature sensor unit and configured to output the temperature of the object. The temperature sensor unit includes a sensor head including a lens with chromatic aberration and a tip member. The sensor head is configured to irradiate the tip member with broadband light generated by the light source through the lens, and is configured to receive return light from the back surface of the tip member. The control unit is configured to output the temperature of the object based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the tip member and the peak wavelength of the return light acquired by the sensor head.

[0016] In this system, broadband light generated by the light source is irradiated onto the tip member through the lens of the sensor head of the temperature sensor unit. Return light from the rear surface of the tip member enters the sensor head and then enters the wavelength acquisition unit. The wavelength acquisition unit acquires the peak wavelength of the return light. The temperature of the tip member is then output based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the tip member and the peak wavelength of the return light acquired by the sensor head. If the tip member is made of a material that has low absorption in the wavelength range of broadband light and a temperature-dependent refractive index, changes in the distance to the rear surface of the tip member are correlated with changes in the temperature of the tip member. Because the light with a wavelength focused on the rear surface of the tip member has the highest return light intensity, the distance to the rear surface of the tip member depends on the peak wavelength of the return light. By acquiring the relationship between the peak wavelength of the return light and the temperature of the tip member in advance, this system can directly convert the measured peak wavelength into the temperature of the tip member. Because the temperature sensor unit is configured to be in thermal contact with the object, the temperature of the temperature sensor unit approximately matches the temperature of the object. Therefore, this system can output the temperature of the object. This system reduces computational costs because it does not require Fourier transform of the intensity distribution of the returned light or calculation of the optical path length ratio, as in conventional methods. Furthermore, this system can measure the temperature of an object as long as the temperature sensor unit is in thermal contact with the object. Therefore, this system can relax the restrictions on the object to be measured compared to infrared temperature sensors. Furthermore, this system can detect temperature faster than a fluorescent thermometer because it does not need to wait for the fluorescence lifetime to expire.

[0017] Yet another aspect of the present disclosure is a method for measuring temperature. The method includes the steps of irradiating an object with broadband light generated by a light source through a lens having chromatic aberration and receiving return light from the back surface of the object, acquiring a peak wavelength of the return light, and outputting the temperature of the object based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the object and the acquired peak wavelength of the return light. The method of the present disclosure achieves the same effects as the above-described system.

[0018] Various embodiments will be described in detail below with reference to the drawings. In the following description and in each drawing, the same or equivalent elements are designated by the same reference numerals, and redundant description will not be repeated. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper," "lower," "left," and "right" are based on the illustrated state and are for convenience.

[0019] [Temperature measurement system overview] FIG. 1 is a diagram illustrating an example of a temperature measurement system according to an exemplary embodiment. The temperature measurement system 1 illustrated in FIG. 1 is a system for measuring the temperature of an object 5. The temperature measurement system 1 measures temperature using the principle of a white light confocal sensor. A white light confocal sensor is a displacement sensor that utilizes the fact that, when broadband light (e.g., white light) is emitted into space through a lens with chromatic aberration and the returned light from the object to be measured is acquired, the returned light has the highest intensity for light of a wavelength that is focused on the surface of the object to be measured. This displacement sensor is used to measure the distance to the back surface of a component made of a material that has low absorption in the wavelength range of the measurement light used and has a refractive index that is temperature-dependent. This makes it possible to measure the temperature of the component made of that material.

[0020] 1, the temperature measurement system 1 includes a light source 10, a sensor head 12, a wavelength acquisition unit 13, and a control unit 14. The temperature measurement system 1 may also include a circulator 11 and a storage unit 15. The light source 10, the circulator 11, the sensor head 12, and the wavelength acquisition unit 13 are connected to each other by optical fibers.

[0021] The object 5 is, for example, plate-shaped. The object 5 has a first main surface 5a and a second main surface 5b opposite to the first main surface 5a. The first main surface 5a and the second main surface 5b may be parallel. In the following description, the first main surface 5a will be referred to as the front surface 5a and the second main surface 5b as the back surface 5b, as necessary. The back surface 5b is the surface to be measured by the temperature measurement system 1. The object 5 to be measured is made of at least one of, for example, Si (silicon), SiO2 (quartz), Al2O3 (sapphire), and SiC (silicon carbide).

[0022] The light source 10 is, for example, a broadband light source. A broadband light source is a light source that generates broadband light. Broadband light is light with a wide wavelength range. The light source 10 can generate light over a wide range of wavelengths, rather than only generating light of a certain wavelength. For example, a broadband light source is configured to emit white light as broadband light. The broadband light source generates light including a predetermined wavelength range, for example, from 180 nm to 6000 nm. The broadband light source is, for example, an SLD (Superluminescent Diode) or an LED (Light-Emitting Diode). As described above, the object 5 is made of a material that has low absorption in the wavelength range of the measurement light used and has a refractive index that is temperature-dependent. When the object 5 is made of quartz, the light source 10 generates light within a wavelength range of 180 nm to 2100 nm, for example. When the object 5 is made of silicon, the light source 10 generates light within a wavelength range of 1200 nm to 6000 nm, for example. In this way, the light source 10 is selected depending on the material of the object 5. In the following description, the measurement light is assumed to be white light, but the measurement light is not limited to white light. The measurement light generated by the light source 10 propagates to the circulator 11. The circulator 11 propagates the measurement light to the sensor head 12.

[0023] The sensor head 12 includes a lens with chromatic aberration. A lens with chromatic aberration has a different focal length for each wavelength. The sensor head 12 is configured to irradiate the object 5 with white light generated by the light source 10 through the lens. Furthermore, the sensor head 12 is configured to receive returning light from the back surface 5b of the object 5. The returning light may include not only light from the back surface 5b of the object 5 but also light reflected from other parts.

[0024] The wavelength acquisition unit 13 receives the returned light via the circulator 11. The wavelength acquisition unit 13 is configured to receive the returned light from the sensor head 12 and acquire the peak wavelength of the returned light. The returned light from the rear surface 5b of the object 5 has the strongest intensity and peaks at a wavelength that is focused by the lens on the rear surface 5b of the object 5. The peak wavelength is the wavelength at which the light intensity peaks when the light intensity for each wavelength is plotted. The wavelength acquisition unit 13 is, for example, a spectrometer, an image sensor, or the like.

[0025] FIG. 2A is a schematic diagram showing an example of a light beam image from the sensor head when the temperature T of the object is temperature T1. Because the sensor head 12 emits white light, it is not the case that only light of a certain wavelength is emitted. However, for ease of understanding, only the light beam of the peak wavelength is illustrated. As shown in FIG. 2A, the sensor head 12 emits white light containing light L1 of wavelength λ1 onto the object 5 (temperature T1) made of a material with a refractive index n1. Although the original focal position (position P1) of light L1 does not reach the back surface 5b of the object 5, due to the refractive index n1 of the material of the object 5, it extends to position P2, which is the position of the back surface 5b of the object 5. Thus, the peak wavelength of the object 5 at temperature T1 is wavelength λ1.

[0026] The refractive index of the object 5 is temperature-dependent. For example, when the temperature of the object 5 rises from T1 to T2, the refractive index changes from n1 to n2. Figure 2B is a schematic diagram showing an example of a light beam image of the sensor head when the object temperature T is T2. As shown in Figure 2B, as the refractive index of the material changes to n2, the focal position of light L1 with wavelength λ1 extends to position P3 and no longer overlaps with the rear surface 5b of the object 5. Instead, the focal position of light L2 with wavelength λ2 extends to position P2 due to the refractive index n2 of the material of the object 5, and becomes the rear surface 5b of the object 5. Thus, the peak wavelength of the object 5 at temperature T2 is wavelength λ2. Note that, in Figures 2A and 2B, the focal length of light with shorter wavelengths is closer; however, depending on the lens configuration of the sensor head 12, the focal length of shorter wavelengths may be longer.

[0027] FIG. 3A shows an example of the relationship between the intensity and wavelength of measurement light, and FIG. 3B shows an example of the relationship between the intensity and wavelength of returned light. As shown in FIG. 3A, the white light irradiated onto the object 5 is light with a wide wavelength band. In contrast, as shown in FIG. 3B, the returned light has the largest intensity from the back surface 5b of the object 5, forming a peak. When the temperature of the object 5 is temperature T1, the light focused on the back surface 5b of the object 5 is light with wavelength λ1, which represents the peak shown by the solid line. When the temperature of the object 5 is temperature T2, the light focused on the back surface 5b of the object 5 is light with wavelength λ2, which represents the peak shown by the dashed line. Thus, the wavelength (peak wavelength) of the light focused on the back surface 5b of the object 5 correlates with temperature. The wavelength acquisition unit 13 detects the peak and can acquire the wavelength (peak wavelength) of the light focused on the back surface 5b of the object 5.

[0028] The control unit 14 may be a computer equipped with a processor, a storage device such as a memory, a display device, an input / output device, a communication device, etc. A series of operations of the temperature measurement system is realized by control by the control unit 14 in accordance with a program stored in the storage device.

[0029] The control unit 14 is configured to output the temperature of the object 5 based on a previously acquired relationship between the peak wavelength of the returned light and the temperature of the object 5 and the peak wavelength of the returned light acquired by the sensor head 12. The previously acquired relationship between the peak wavelength of the returned light and the temperature of the object 5 is stored, for example, in a storage unit 15 that can be referenced by the control unit 14. The storage unit 15 is, for example, a storage medium such as an HDD (Hard Disk Drive).

[0030] FIG. 4 is a table showing an example of the relationship between peak wavelength and temperature. As shown in FIG. 4, peak wavelength and temperature are associated with each other. For example, when the peak wavelength is λ1, the temperature of the object 5 is T1. For example, when the peak wavelength is λ2, the temperature of the object 5 is T2. For example, when the peak wavelength is λ3, the temperature of the object 5 is T3. In this way, once the peak wavelength is determined, the temperature of the object 5 is determined. Note that the relationship between peak wavelength and temperature is not limited to the table format shown in FIG. 4, but may be a mathematical formula using the peak wavelength and temperature as parameters.

[0031] The control unit 14, for example, refers to the table shown in Fig. 4 stored in the storage unit 15, and acquires the temperature corresponding to the measured peak wavelength. Then, the control unit 14 outputs the temperature of the object 5. "Output" includes not only transmitting the temperature to another component, but also displaying it on a display device such as a monitor or storing it in a storage device.

[0032] [Displacement measurement method] 5 is a flowchart of a method using the temperature measurement system. As shown in FIG. 5, in the method MT, step S10 is first executed. In step S10, the control unit 14 turns on the power of the light source 10 and causes the white light generated by the light source 10 to propagate to the sensor head 12. The sensor head 12 irradiates the object 5 with the white light and receives return light from the back surface 5b of the object 5.

[0033] Next, step S12 is executed. In step S12, the wavelength acquisition unit 13 acquires the peak wavelength of the returned light obtained in step S10. For example, as shown in FIG. 3B, the wavelength acquisition unit 13 acquires the light intensity for each wavelength and acquires the wavelength at which the light intensity is at its peak as the peak wavelength.

[0034] Next, step S14 is executed. In step S14, the control unit 14 outputs the temperature of the object 5 based on the peak wavelength obtained in step S12. For example, the control unit 14 refers to the table shown in FIG. 4 and acquires the temperature corresponding to the peak wavelength obtained in step S12. The control unit 14 outputs the acquired temperature as the temperature of the object 5. When step S14 is completed, the flowchart shown in FIG. 5 ends.

[0035] Summary of Exemplary Embodiments In the temperature measurement system 1, white light generated by the light source 10 is irradiated onto the object through the lens of the sensor head 12. Return light from the back surface 5b of the object 5 enters the sensor head 12 and then enters the wavelength acquisition unit 13 from the sensor head 12. The wavelength acquisition unit 13 acquires the peak wavelength of the return light. The temperature of the object 5 is then output based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the object 5 and the peak wavelength of the return light acquired by the sensor head 12. If the object 5 is made of a material that has low absorption in the wavelength range of white light and a temperature-dependent refractive index, changes in the distance to the back surface 5b of the object 5 are correlated with changes in the temperature of the object 5. Because the intensity of the return light is highest for light with a wavelength that is focused on the back surface 5b of the object 5, the distance to the back surface 5b of the object 5 depends on the peak wavelength of the return light. By previously acquiring the relationship between the peak wavelength of the return light and the temperature of the object 5, the temperature measurement system 1 can directly convert the measured peak wavelength into the temperature of the object 5. Therefore, the temperature measurement system 1 does not need to perform a Fourier transform on the intensity distribution of the returned light or calculate the optical path length ratio, as in conventional methods, thereby reducing computational costs. The temperature measurement system 1 can measure the temperature of any object 5 made of a material that has low absorption in the wavelength range of white light and has a temperature-dependent refractive index. Therefore, the temperature measurement system 1 can relax the restrictions on the object to be measured compared to an infrared temperature sensor. Furthermore, because the temperature measurement system 1 does not need to wait for the fluorescence lifetime to expire, it can detect temperature faster than a fluorescent thermometer.

[0036] [Variations] It will be understood that various modifications can be made to the embodiments of the present disclosure without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

[0037] [Application to substrate processing equipment] For example, the temperature measurement system 1 described in one embodiment may be installed in a substrate processing apparatus. FIG. 6 is a diagram schematically illustrating an example of a substrate processing apparatus according to an illustrative embodiment. In FIG. 6, the object 5 is a wafer Tw, but the object 5 may be any component housed in the substrate processing apparatus 300. The component housed in the substrate processing apparatus 300 may be, for example, at least one of a wafer, a focus ring, and an upper electrode. The substrate processing apparatus 300 is, for example, a plasma etching apparatus.

[0038] Light that is transmitted through and reflected from both end surfaces S1 and S2 of the wafer Tw, which is the object, is used as the light source 10. For example, since the wafer Tw is made of silicon, a light source that can irradiate light having a wavelength of 1.2 to 2.5 μm that can transmit through silicon materials such as silicon and silicon oxide film is used as the light source 10.

[0039] As shown in FIG. 9 , the substrate processing apparatus 300 includes a processing chamber 310 in which a predetermined process, such as an etching process or a film formation process, is performed on a wafer Tw. The wafer Tw is accommodated in the processing chamber 310. The processing chamber 310 is connected to an exhaust pump (not shown) and configured to be able to evacuate. An upper electrode 350 and a lower electrode 340 facing the upper electrode 350 are disposed inside the processing chamber 310. The lower electrode 340 also serves as a holder for holding the wafer Tw. An electrostatic chuck (not shown) that electrostatically attracts the wafer Tw is disposed above the lower electrode 340. The lower electrode 340 is also provided with a cooling means. The cooling means controls the temperature of the lower electrode 340 by circulating a cooling medium through a cooling medium flow path 342 formed in a substantially annular shape in the lower electrode 340. This controls the temperature of the wafer Tw. The wafer Tw is loaded into the processing chamber 310 through, for example, a gate valve (not shown) provided on the side of the processing chamber 310. High frequency power supplies 320 and 330 that apply predetermined high frequency power are connected to the lower electrode 340 and the upper electrode 350, respectively.

[0040] The upper electrode 350 is configured such that an electrode plate 351 located at the bottom is supported by an electrode support 352. The electrode plate 351 is made of, for example, a silicon material (silicon, silicon oxide, etc.), and the electrode support 352 is made of, for example, an aluminum material. An inlet pipe (not shown) through which a predetermined process gas is introduced is provided above the upper electrode 350. A large number of discharge holes (not shown) are formed in the electrode plate 351 so that the process gas introduced from this inlet pipe is uniformly discharged toward the wafer Tw placed on the lower electrode 340.

[0041] The upper electrode 350 is provided with a cooling means. This cooling means controls the temperature of the upper electrode 350, for example, by circulating a refrigerant through a refrigerant channel formed in an electrode support 352 of the upper electrode 350. The refrigerant channel is formed in a substantially annular shape and is divided into two systems: an outer refrigerant channel 353 for cooling the outer side of the surface of the upper electrode 350, and an inner refrigerant channel 354 for cooling the inner side. These outer refrigerant channel 353 and inner refrigerant channel 354 are each configured so that a refrigerant is supplied from a supply pipe, flows through each refrigerant channel 353, 354, and is discharged from a discharge pipe, as indicated by the arrows in FIG. 9, and returns to an external refrigerator (not shown) for circulation. The same refrigerant may be circulated through these two refrigerant channel systems, or different refrigerants may be circulated through these two refrigerant channel systems. Note that the cooling means for the upper electrode 350 is not limited to the two refrigerant channel systems shown in FIG. 9, but may instead be provided with only one refrigerant channel system, or may be provided with one refrigerant channel system branched into two.

[0042] The electrode support 352 is provided with a low heat transfer layer 356 between an outer region where the outer refrigerant flow path 353 is provided and an inner region where the inner refrigerant flow path 354 is provided. As a result, heat is not easily transferred between the outer region and the inner region of the electrode support 352 due to the action of the low heat transfer layer 356, and therefore it is possible to control the outer region and the inner region to have different temperatures by controlling the refrigerants in the outer refrigerant flow path 353 and the inner refrigerant flow path 354. In this way, it becomes possible to efficiently and accurately control the in-plane temperature of the upper electrode 350.

[0043] In such a substrate processing apparatus 300, the wafer Tw is loaded via a gate valve by, for example, a transfer arm. The wafer Tw loaded into the processing chamber 310 is placed on the lower electrode 340, and high-frequency power is applied to the upper electrode 350 and the lower electrode 340, while a predetermined processing gas is introduced from the upper electrode 350 into the processing chamber 310. As a result, the processing gas introduced from the upper electrode 350 is converted into plasma, and the surface of the wafer Tw is subjected to, for example, etching processing.

[0044] The output light in the temperature measurement system 1 is irradiated from the lower electrode 340 to the wafer Tw, which is the object to be measured, via the optical element 30. Specifically, the optical element 30 is disposed so that the output light is irradiated to the wafer Tw via a through-hole 344 formed in, for example, the center of the lower electrode 340. Note that the position in the in-plane direction of the wafer Tw where the optical fiber is disposed does not have to be the center of the wafer Tw as shown in FIG. 6, as long as it is a position where the output light is irradiated to the wafer Tw. For example, the optical fiber may be disposed so that the output light is irradiated to the edge of the wafer Tw.

[0045] As described above, the temperature of at least one of the substrate, focus ring, and upper electrode can be measured by installing the temperature measurement system 1 in the substrate processing apparatus 300. In addition, the temperature of the wafer Tw, which is an object being etched, can be measured.

[0046] [Peak wavelength correction] The temperature measurement system 1 may have a function for correcting the peak wavelength. The peak wavelength may be subject to an error depending on the temperature of the optical system of the sensor head 12.

[0047] FIG. 7A is a schematic diagram showing an example of a light beam image of the sensor head when the lens temperature T is temperature T3. Because the sensor head 12 emits white light, it is not the case that only light of a certain wavelength is emitted. However, for ease of understanding, only the light beam of the peak wavelength is illustrated. As shown in FIG. 7A, the sensor head 12 (temperature T3) emits white light containing light L3 of wavelength λ3 onto the object 5 (temperature T1) made of a material with a refractive index n1. Although the original focal position (position P4) of light L3 does not reach the back surface 5b of the object 5, due to the refractive index n1 of the material of the object 5, it extends to position P2, which becomes the position of the back surface 5b of the object 5. Thus, when the sensor head 12 is at temperature T3, the peak wavelength of the object 5 is wavelength λ3.

[0048] The lens 12a of the sensor head 12 may heat up from temperature T3 to temperature T4 due to fluctuations in the ambient temperature or irradiation with white light. FIG. 7B is a schematic diagram showing an example of a light beam image of the sensor head when the lens temperature T is temperature T4. As shown in FIG. 7B, as the temperature of the sensor head 12 changes to temperature T4, the focal position of the light L3 with wavelength λ3 extends to position P5 and no longer overlaps with the rear surface 5b of the object 5. Instead, the focal position of the light L4 with wavelength λ4 extends to position P2 due to the temperature change of the sensor head 12 and becomes the rear surface 5b of the object 5. Thus, the peak wavelength of the object 5 at temperature T2 is wavelength λ4. While FIGS. 7A and 7B illustrate an example in which the focal length increases as the temperature of the lens 12a increases, the focal length may also decrease as the temperature of the lens 12a increases.

[0049] The control unit 14 acquires the temperature of the lens 12a based on the light returned from the object 5 when the temperature is unchanged, and calculates a correction value for the peak wavelength corresponding to the temperature. This calculation of the correction value is achieved by measuring a fixed length, so light returned from the surface 5a of the object 5 may also be used. In other words, the control unit 14 can acquire the peak wavelength related to the temperature of the object 5 based on the light returned from the back surface 5b of the object 5, while calculating a correction value that corrects for changes in the peak wavelength due to temperature changes of the lens 12a based on the light returned from the surface 5a of the object 5. The control unit 14 then corrects the peak wavelength related to the temperature of the object 5 using the correction value to calculate the final peak wavelength. The control unit 14 outputs the temperature corresponding to the final peak wavelength as the temperature of the object 5. This configuration allows the temperature measurement system 1 to measure the temperature of the object 5 with greater accuracy.

[0050] [Built-in or contact temperature sensor] Although the temperature measurement systems described so far irradiate the object 5 directly with light, the temperature of the object 5 may also be measured without irradiating the object 5 directly with light. FIG. 8 is a diagram showing an example of a temperature measurement system according to another exemplary embodiment. Compared to the temperature measurement system 1 shown in FIG. 1, the temperature measurement system 1A shown in FIG. 8 differs in that it includes a temperature sensor unit 2 that houses a sensor head 12, but the other configurations are the same. In explaining the temperature measurement system 1A, the differences from the temperature measurement system 1 will be mainly explained, and duplicate explanations will be omitted.

[0051] 8, the temperature measurement system 1A includes a light source 10, a temperature sensor unit 2, a wavelength acquisition unit 13, and a control unit 14. The temperature measurement system 1A may also include a circulator 11 and a storage unit 15. The light source 10, the circulator 11, the temperature sensor unit 2, and the wavelength acquisition unit 13 are connected to each other by optical fibers. The light source 10 has the same configuration as the light source of the temperature measurement system 1.

[0052] The object 5 is not particularly limited as long as it is an object in which the temperature sensor unit 2 can be embedded or attached. The temperature sensor unit 2 is configured to be in thermal contact with the object 5. The temperature sensor unit 2 generates return light using white light generated by the light source 10.

[0053] FIG. 9A is a schematic diagram showing an example of the configuration of the temperature sensor unit. As shown in FIG. 9A, the temperature sensor unit 2 includes a sensor head 12 and a tip member 16. The sensor head 12 and the tip member 16 are housed in a sleeve 17, and their relative positions are fixed. The sleeve 17 is made of, for example, stainless steel, aluminum, ceramic, quartz, sapphire, or the like. To improve the accuracy of measuring the temperature of the object 5, the sleeve 17 may be made of the same material as the object 5. The tip member 16 is a member that is irradiated with white light from the sensor head 12. To improve the accuracy of measuring the temperature of the object 5, the tip member 16 may also be made of the same material as the object 5. In the temperature sensor unit 2 integrated with the sleeve 17, the temperatures of the components that make up the temperature sensor unit 2 are the same or approximately the same.

[0054] The tip member 16 is, for example, plate-shaped or block-shaped. The tip member 16 has a first main surface 16a and a second main surface 16b opposite the first main surface 16a. The first main surface 16a and the second main surface 16b may be parallel. In the following description, the first main surface 16a will be referred to as the front surface 16a and the second main surface 16b as the back surface 16b, as necessary. The back surface 16b is the surface to be measured by the temperature measurement system 1A. The tip member 16 is made of a material that has low absorption in the wavelength range of the measurement light used and has a refractive index that is temperature-dependent. The tip member 16 to be measured is made of, for example, at least one of silicon, quartz, sapphire, and silicon carbide.

[0055] The sensor head 12 includes a lens 12a with chromatic aberration. The lens 12a has a different focal length for each wavelength. The sensor head 12 is configured to irradiate the tip member 16 with white light generated by the light source 10 through the lens 12a. Furthermore, the sensor head 12 is configured to receive returning light from the rear surface 16b of the tip member 16. The returning light may include not only light from the rear surface 16b of the tip member 16 but also light reflected from other parts.

[0056] The wavelength acquisition unit 13 has the same configuration as the wavelength acquisition unit of the temperature measurement system 1.

[0057] The control unit 14 is configured to output the temperature of the object 5 based on a previously acquired relationship between the peak wavelength of the returned light and the temperature of the tip member 16 and the peak wavelength of the returned light acquired from the temperature sensor unit 2. The memory unit 15 stores the previously acquired relationship between the peak wavelength of the returned light and the temperature of the tip member 16, similar to the table shown in FIG. 4. The control unit 14, for example, references the relationship stored in the memory unit 15 and acquires the temperature of the tip member 16 corresponding to the measured peak wavelength. The control unit 14 then outputs the temperature of the tip member 16 as the temperature of the object 5. "Output" includes not only transmitting it to another component but also displaying it on a display device or storing it in a storage device.

[0058] In the temperature measurement system 1A, white light generated by the light source 10 is irradiated onto the tip member 16 through the lens 12a of the sensor head 12 of the temperature sensor unit 2. Return light from the rear surface 16b of the tip member 16 enters the sensor head 12 and then enters the wavelength acquisition unit 13. The wavelength acquisition unit 13 acquires the peak wavelength of the return light. The temperature of the tip member 16 is then output based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the tip member 16 and the peak wavelength of the return light acquired by the sensor head 12. If the tip member 16 is made of a material that has low absorption in the wavelength range of white light and a temperature-dependent refractive index, changes in the distance to the rear surface 16b of the tip member 16 are correlated with changes in the temperature of the tip member 16. Because light with a wavelength that is focused on the rear surface 16b of the tip member 16 has the highest return light intensity, the distance to the rear surface 16b of the tip member 16 depends on the peak wavelength of the return light. By acquiring the relationship between the peak wavelength of the returned light and the temperature of the tip component 16 in advance, the temperature measurement system can directly convert the measured peak wavelength into the temperature of the tip component 16. Because the temperature sensor unit 2 is configured to be in thermal contact with the object 5, the temperature of the temperature sensor unit 2 nearly coincides with the temperature of the object 5. Therefore, the temperature measurement system 1A can output the temperature of the object 5. The temperature measurement system 1A does not require Fourier transform of the intensity distribution of the returned light or calculation of the optical path length ratio, as in conventional methods, thereby reducing computational costs. Furthermore, the temperature measurement system 1A can measure the temperature of the object 5 as long as the temperature sensor unit 2 is in thermal contact with the object 5. Therefore, the temperature measurement system 1A can relax the limitations on the object to be measured compared to infrared temperature sensors. Furthermore, because the temperature measurement system 1A does not need to wait for the fluorescence lifetime to expire, it can detect temperature faster than a fluorescent thermometer.

[0059] The temperature measurement system 1A may have the function of correcting the peak wavelength described above. Also, the temperature measurement system 1A may measure the temperature of the lens 12a of the sensor head 12, i.e., the temperature of the temperature sensor unit 2, using the return light from the surface 16a of the tip member 16.

[0060] The temperature sensor unit 2 does not necessarily have to include the sleeve 17. Fig. 9(B) is a schematic diagram showing another example of the configuration of the temperature sensor unit. As shown in Fig. 9(B), in the temperature sensor unit 2A, the sensor head 12 and the tip member 16 may be fixed in direct contact with each other. Specifically, the sensor head 12 and the tip member 16 may be bonded together. The temperature sensor unit 2A achieves the same effects as when the temperature sensor unit 2 is used, and can also be made lighter.

[0061] In the temperature measurement system 1A, at least one of the front surface 16a and the back surface 16b of the tip member 16 may be optically treated. For example, the back surface 16b, which is the reflecting surface of the measurement light, may be coated with a multilayer dielectric film or with aluminum or gold to increase the reflectivity of the back surface 16b. Increasing the reflectivity of the back surface 16b clarifies the spectrum of the returned light. Alternatively, the front surface 16a, which is the incident surface of the measurement light, may be coated with an anti-reflection film. In this case, reflection on the front surface 16a is suppressed, thereby clarifying the spectrum of the returned light. [Explanation of symbols]

[0062] 1,1A...temperature measurement system, 2,2A...temperature sensor section, 10...light source, 12...sensor head, 12a...lens, 13...wavelength acquisition section, 14...control section.

Claims

1. a light source configured to emit broadband light; a sensor head including a lens having chromatic aberration, configured to irradiate an object with broadband light generated by the light source through the lens, and configured to receive return light from a rear surface of the object; a wavelength acquisition unit configured to receive return light from the sensor head and acquire a peak wavelength of the return light; a control unit configured to output the temperature of the object based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the object and the peak wavelength of the return light acquired by the sensor head; A system for measuring temperature, comprising:

2. The control unit calculating a correction value for correcting a change in peak wavelength caused by a change in temperature of the lens based on the return light from the surface of the object; The system of claim 1 , wherein the correction value is used to correct a peak wavelength of the returned light.

3. a light source configured to emit broadband light; a temperature sensor unit configured to be in thermal contact with the object and generating return light using the broadband light generated by the light source; a wavelength acquisition unit configured to receive return light from the temperature sensor unit and acquire a peak wavelength of the return light; a control unit connected to the temperature sensor unit and configured to output the temperature of the object; Equipped with the temperature sensor unit has a sensor head including a lens having chromatic aberration and a tip member, The sensor head is configured to irradiate the tip member with broadband light generated by the light source through the lens, and to receive return light from a back surface of the tip member, the control unit is configured to output the temperature of the object based on a relationship acquired in advance between a peak wavelength of the return light and the temperature of the tip member and the peak wavelength of the return light acquired by the sensor head. A system for measuring temperature.

4. a step of irradiating a target object with broadband light generated by a light source through a lens having chromatic aberration, and allowing return light from a rear surface of the target object to be incident thereon; obtaining a peak wavelength of the returned light; outputting the temperature of the object based on a previously acquired relationship between the peak wavelength of the return light and the temperature of the object and the acquired peak wavelength of the return light; A method for measuring temperature, comprising:

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