Radiation temperature measurement device, radiation temperature measurement method, and radiation temperature measurement program

Abstract

A radiation temperature measurement device 100 that detects infrared rays radiated from a measurement subject W to measure the temperature of the measurement subject W, the radiation temperature measurement device 100 comprising: an infrared ray detection unit 2 that detects the respective infrared ray amounts of a plurality of wavelength components and that detects the infrared ray amount of each of a plurality of polarization components in at least one of the plurality of wavelength components; and a temperature computation unit 3 that computes the temperature of the measurement subject W on the basis of at least three kinds of infrared ray amounts detected by the infrared ray detection unit 2.

Description

Radiation temperature measuring device, radiation temperature measuring method, and radiation temperature measuring program

[0001] The present invention relates to a radiation temperature measuring device, a radiation temperature measuring method, and a radiation temperature measuring program.

[0002] Conventionally, a wavelength differential type radiation thermometer has been proposed, as disclosed in Patent Document 1. This radiation thermometer measures the temperature of a wafer using two wavelengths with different emissivities. In addition, by placing the radiation thermometer above the wafer in a position directly facing the surface of the wafer, the reflected component from the wafer is considered to be infrared radiation from the radiation thermometer, and the temperature is calculated.

[0003] However, in dry etching equipment, etc., the presence of electrodes above the wafer makes it impossible to place the radiation thermometer above the wafer, so in such cases, it is necessary to place the radiation thermometer on the side wall of the chamber, for example, and measure the wafer from an oblique angle.

[0004] Here, when measuring from an oblique angle, the wafer and the radiation thermometer are not directly facing each other, so the infrared rays that are reflected from the wafer surface and incident on the radiation thermometer are not infrared rays from the radiation thermometer but are incident on something other than the radiation thermometer (for example, a component on which the radiation thermometer is reflected, such as the inner wall of the chamber), making it impossible to calculate the temperature as a known value.

[0005] In the case of the conventional wavelength difference method, the following two relational expressions can be obtained from two wavelengths with different emissivity of the wafer, but they cannot be solved because there are three unknowns: the wafer temperature Tx, the temperature of the member at the reflection destination (reflection destination temperature) Tr, and the temperature of the member on the backside of the wafer (wafer backside temperature) Tb. １ = ε １ ・F １ (Tx) + r １ ・F １ (Tr) + t １ ・F １ (Tb) E ２ = ε ２ ・F ２ (Tx) + r ２ ・F ２ (Tr) + t ２ ・F ２ (Tb) where ε １is the emissivity of the wafer at the first wavelength, r １ is the reflectivity of the wafer at the first wavelength, t １ is the transmittance of the wafer at the first wavelength, and ε ２ is the emissivity of the wafer at the second wavelength, r ２ is the reflectivity of the wafer at the second wavelength, t ２ is the transmittance of the wafer at the second wavelength.

[0006] International Publication No. 2021 / 080002

[0007] Therefore, the present invention has been made in consideration of the above-mentioned problems, and its main object is to provide a wavelength differential type radiation temperature measuring device that can accurately determine the temperature of an object to be measured, regardless of infrared components from the surroundings that are reflected by the object to be measured.

[0008] That is, the radiation temperature measuring device of the present invention is a radiation temperature measuring device that detects infrared rays radiated from a measurement object and measures the temperature of the measurement object, and is characterized by comprising an infrared detection unit that detects the amount of infrared rays for each of a plurality of wavelength components and detects the amount of infrared rays for each of a plurality of polarization components in at least one of the plurality of wavelength components, and a temperature calculation unit that calculates the temperature of the measurement object based on the amount of at least three types of infrared rays detected by the infrared detection unit.

[0009] Such a radiation temperature measuring device detects the amount of infrared light for each of multiple wavelength components, and also detects the amount of infrared light for each of multiple polarization components in at least one of the multiple wavelength components, and calculates the temperature of the object to be measured based on the detected amounts of at least three types of infrared light.Therefore, the temperature of the object to be measured can be determined accurately regardless of the infrared light components from the surroundings that are reflected by the object to be measured.

[0010] The infrared detection unit preferably includes a first infrared sensor that detects the amount of infrared at a first wavelength, and a second infrared sensor that detects the amount of infrared at a second wavelength, the emissivity of which is different from that of the first wavelength.

[0011] It is desirable that the infrared detection unit further includes a polarizer provided in front of the first infrared sensor and the second infrared sensor, and that the first infrared sensor detects the amount of infrared light for each of two different polarization components of the first wavelength, and the second infrared sensor detects the amount of infrared light for each of two different polarization components of the second wavelength.

[0012] It is desirable that the first infrared sensor detects the amount of p-polarized infrared light of the first wavelength and the amount of s-polarized infrared light of the first wavelength, and the second infrared sensor detects the amount of p-polarized infrared light of the second wavelength and the amount of s-polarized infrared light of the second wavelength.

[0013] In order to simultaneously measure the amounts of p-polarized and s-polarized infrared light to improve responsiveness and minimize a decrease in the amount of infrared light, it is desirable that the infrared detection unit further include a polarizer arranged at an angle of 20 to 65 degrees with respect to the incident infrared light, which transmits either p-polarized or s-polarized infrared light and reflects the other p-polarized or s-polarized infrared light. In this configuration, the first infrared sensor includes a first transmission infrared sensor that detects the amount of infrared light of the first wavelength, either p-polarized or s-polarized light, that has transmitted through the polarizer, and a first reflection infrared sensor that detects the amount of infrared light of the first wavelength, either p-polarized or s-polarized light, that has reflected from the polarizer. Furthermore, the second infrared sensor includes a second transmission infrared sensor that detects the amount of infrared light of the second wavelength, either p-polarized or s-polarized light, that has transmitted through the polarizer, and a second reflection infrared sensor that detects the amount of infrared light of the second wavelength, either p-polarized or s-polarized light, that has reflected from the polarizer.

[0014] In order to use the radiation temperature measuring device appropriately when it is not possible to place it directly opposite the surface of the object to be measured, it is desirable that the infrared detection unit detects the amount of infrared rays at a position inclined with respect to the surface of the object to be measured.

[0015] As a specific arrangement of the infrared detection unit, it is conceivable that the infrared detection unit detects the amount of infrared rays at a position inclined so that the angle formed with the surface of the measurement object is the Brewster angle.

[0016] The temperature calculation unit can solve the problem using the conventional dichotomy method by combining the relational equations for at least three types of detected infrared radiation, eliminating one of the three unknown temperatures (the temperature of the object being measured, the temperature of the material behind the object being measured, and the temperature of the material emitting the infrared radiation reflected by the object being measured). However, actual detection signals contain noise from the infrared sensor, and while combining the relational equations reduces the number of unknowns, it becomes more susceptible to the influence of noise. For this reason, it is desirable for the temperature calculation unit to calculate the temperature of the object being measured using an optimization calculation method from at least three types of infrared radiation detected by the infrared detection unit. This configuration reduces the influence of noise from the infrared sensor and allows the temperature of the object to be determined accurately.

[0017] Furthermore, it is desirable that the temperature calculation unit calculates, in addition to the temperature of the object to be measured, the temperature of a member on the back surface of the object to be measured and / or the temperature of a member that emits infrared rays reflected by the object to be measured.

[0018] Specifically, it is desirable that the temperature calculation unit calculates the temperature of the object to be measured from the amount of at least three types of infrared rays detected by the infrared detection unit using a Kalman filter as an optimization calculation method.

[0019] Furthermore, a radiation temperature measurement method according to the present invention is a radiation temperature measurement method for detecting infrared rays emitted from a measurement object and measuring the temperature of the measurement object, which is characterized in that it detects the amount of infrared rays for each of a plurality of wavelength components, and detects the amount of infrared rays for each of a plurality of polarization components in at least one of the plurality of wavelength components, and calculates the temperature of the measurement object based on the detected amounts of at least three types of infrared rays.

[0020] Furthermore, the radiation temperature measurement program of the present invention is a radiation temperature measurement program used in a radiation temperature measurement device that includes an infrared detection unit that detects the amount of infrared light for each of a plurality of wavelength components in infrared light radiated from a measurement object and detects the amount of infrared light for each of a plurality of polarization components in at least one of the plurality of wavelength components, and is characterized in that the program has a computer function as a temperature calculation unit that calculates the temperature of the measurement object based on the amount of at least three types of infrared light detected by the infrared detection unit.

[0021] The radiation temperature measurement program may be distributed electronically or may be recorded on a program recording medium such as a CD, DVD, or flash memory.

[0022] According to the present invention as described above, in a wavelength differential type radiation temperature measuring device, the temperature of the object to be measured can be determined with high accuracy regardless of the infrared components from the surroundings that are reflected by the object to be measured.

[0023] FIG. 1 is a diagram showing a state in which a radiation thermometer is disposed in a semiconductor manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a graph showing the transmittance, reflectance, and emissivity of a silicon wafer for s-polarized light and p-polarized light (left: first wavelength (9.3-14 μm), right: second wavelength (7-7.8 μm)). FIG. 3 is a diagram showing a schematic configuration of the radiation thermometer according to the embodiment (a configuration in which each infrared detection unit has two infrared detectors). FIG. 4 is a graph showing an indication error when an optimization calculation method is used and an indication error when calculation is performed by eliminating unknowns in the temperature calculation unit according to the embodiment. FIG. 5 is a diagram showing a schematic configuration of a radiation thermometer according to a modified embodiment (a configuration in which each infrared detection unit has one infrared detector). FIG. 6 is a diagram showing a schematic configuration of a radiation thermometer according to a modified embodiment. FIG. 7 is a diagram showing a schematic configuration of a radiation thermometer according to a modified embodiment.

[0024] <One embodiment of the present invention> Hereinafter, one embodiment of a radiation temperature measuring device according to the present invention will be described with reference to the drawings. Note that in all of the drawings shown below, parts are appropriately omitted or exaggerated for ease of understanding. Identical components are assigned the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0025] 1, the radiation thermometer 100 of this embodiment is disposed in a processing chamber 200 of a semiconductor manufacturing apparatus such as a plasma etching apparatus, and measures the temperature of a measurement object W, such as a wafer, being processed in the processing chamber 200. The radiation thermometer 100 is disposed on a sidewall of the processing chamber 200, and measures the temperature of the measurement object W from diagonally above.

[0026] 2, the radiation temperature measuring device 100 includes an infrared detection unit 2 that detects infrared rays radiated from the measurement object W, and a temperature calculation unit 3 that calculates the temperature of the measurement object W based on the amount of infrared rays detected by the infrared detection unit 2. The measurement object W in this embodiment has the properties of radiating, reflecting, and transmitting infrared rays, and is, for example, a silicon wafer.

[0027] <Infrared Detector 2> The infrared detector 2 detects the amount of infrared light for each of a plurality of wavelength components, and also detects the amount of infrared light for each of a plurality of polarization components in at least one of the plurality of wavelength components. １ The amount of infrared light for each of the two polarization components (here, s-polarized and p-polarized) at the first wavelength λ １ A second wavelength λ different from ２ The amount of infrared light for each of the two polarized components (here, s-polarized light and p-polarized light) is detected.

[0028] 1, the infrared detection unit 2 detects the amount of infrared light at a position inclined with respect to the surface of the measurement object W. Here, as shown in FIG. 2, the angle dependence of the emissivity ε, reflectance r, and transmittance t of s-polarized light and p-polarized light of the measurement object W (here, a silicon wafer) changes significantly as the angle becomes more inclined, and at the Brewster angle (74 degrees), the reflectance r of s-polarized light is ｓ and the reflectivity of p-polarized light r ｐ The difference between the reflectance and transmittance of s-polarized light and p-polarized light is maximized. Since the measurement method of this embodiment utilizes the difference between the reflectance and transmittance of s-polarized light and p-polarized light (ΔR = Rs - Rp, ΔT = Ts - Tp), it is desirable that the infrared detection unit 2 detect the amount of infrared light at a position tilted at an angle that generates the difference between the s-polarized light and p-polarized light (ΔR, ΔT). Furthermore, since the Brewster angle maximizes ΔR and ΔT, it is desirable that the infrared detection unit 2 detect the amount of infrared light at a position tilted so that the angle it forms with the surface of the measurement object W is the Brewster angle.

[0029] Specifically, the infrared detection unit 2 detects a first wavelength λ １ a first infrared sensor 21 for detecting an amount of infrared light having a second wavelength λ ２ and a polarizer 23 provided in front of the first infrared sensor 21 and the second infrared sensor 22. In addition, the infrared detection unit 2 includes a condenser lens 24 that condenses infrared light, and a polarizer 25 that condenses infrared light having a first wavelength λ. １ or the second wavelength λ ２ (here, the second wavelength λ ２ ) and transmits the other (here, the first wavelength λ １ The infrared sensors 21 and 22 each include a sensor element such as a thermopile that detects infrared rays.

[0030] The first infrared sensor 21 detects the amount of p-polarized infrared light of a first wavelength and the amount of s-polarized infrared light of a first wavelength, while the second infrared sensor 22 detects the amount of p-polarized infrared light of a second wavelength and the amount of s-polarized infrared light of a second wavelength.

[0031] Here, two first infrared sensors 21 are provided, with a polarizer 23a for extracting s-polarized light provided in front of one first infrared sensor 21a, and a polarizer 23b for extracting p-polarized light provided in front of the other first infrared sensor 21b. Note that infrared light is split and incident on the two infrared sensors 21a, 21b by a half mirror 26a. Two second infrared sensors 22 are also provided, with a polarizer 23c for extracting s-polarized light provided in front of one second infrared sensor 22a, and a polarizer 23d for extracting p-polarized light provided in front of the other second infrared sensor 22b. Note that infrared light is split and incident on the two infrared sensors 22a, 22b by the half mirror 26b.

[0032] <Temperature Calculation Unit 3> The temperature calculation unit 3 calculates the temperature of the measurement object W based on the amount of at least three types of infrared rays (values ​​of the detection signals of the sensors 21 and 22) detected by the infrared detection unit 2. In this embodiment, the first wavelength λ １ The amount of s-polarized infrared light E １,ｓ , first wavelength λ １ The amount of p-polarized infrared light E １,ｐ , second wavelength λ ２ The amount of s-polarized infrared light E ２,ｓ , and the second wavelength λ ２ The amount of p-polarized infrared light E ２,ｐ The temperature of the object W to be measured is calculated based on the above.

[0033] Specifically, the temperature calculation unit 3 calculates three unknowns (the temperature Tx of the measurement object, the temperature Tr (reflected component temperature) of the reflection target member (e.g., the side wall of the chamber) that emits the infrared rays reflected by the measurement object W, and the temperature Tb (transmitted component temperature) of the member on the back side of the measurement object W) from the following four relational expressions. In other words, the temperature calculation unit 3 calculates the temperature of the measurement object W using relational expressions including parameters using the three unknowns (the temperature Tx of the measurement object, the temperature Tr (reflected component temperature) of the reflection target member (e.g., the side wall of the chamber) that emits the infrared rays reflected by the measurement object W, and the temperature Tb (transmitted component temperature) of the member on the back side of the measurement object W).

[0034] E １,ｓ = ε １,ｓ ・F １ (Tx) + r １,ｓ ・F１ (Tr) + t １,ｓ ・F １ (Tb) E １,ｐ = ε １,ｐ ・F １ (Tx) + r １,ｐ ・F １ (Tr) + t １,ｐ ・F １ (Tb) E ２,ｓ = ε ２,ｓ ・F ２ (Tx) + r ２,ｓ ・F ２ (Tr) + t ２,ｓ ・F ２ (Tb) E ２,ｐ = ε ２,ｐ ・F ２ (Tx) + r ２,ｐ ・F ２ (Tr) + t ２,ｐ ・F ２ (Tb)

[0035] where ε １,ｓ is the first wavelength λ １ The emissivity of the measurement object W in s-polarized light is ε １,ｐ is the first wavelength λ １ The emissivity of the measurement object W in p-polarized light is r １,ｓ is the first wavelength λ １ The reflectivity of the measurement object W in s-polarized light, r １,ｐ is the first wavelength λ １ The reflectivity of the measurement object W in p-polarized light, t １,ｓ is the first wavelength λ １ transmittance of the measurement object W in s-polarized light, t １,ｐ is the first wavelength λ １ is the transmittance of the measurement object W in p-polarized light. ２,ｓ is the second wavelength λ ２ The emissivity of the measurement object W in s-polarized light is ε ２,ｐ is the second wavelength λ ２ The emissivity of the measurement object W in p-polarized light is r ２,ｓ is the second wavelength λ ２ The reflectivity of the measurement object W in s-polarized light, r ２,ｐ is the second wavelength λ ２ The reflectivity of the measurement object W in p-polarized light, t ２,ｓ is the second wavelength λ ２transmittance of the measurement object W in s-polarized light, t ２,ｐ is the second wavelength λ ２ is the transmittance of the measurement object W in p-polarized light.

[0036] The temperature calculation unit 3 calculates three unknowns (temperature Tx of the object to be measured, reflected component temperature Tr, and transmitted component temperature Tb) from the above four relational expressions using an optimization calculation method. Specifically, the temperature calculation unit 3 uses a Kalman filter, such as an unscented Kalman filter or an extended Kalman filter, as the optimization calculation method to calculate the temperature of the object to be measured W. In addition to the Kalman filter, the temperature calculation unit 3 may also use a particle filter or a Gaussian filter. The temperature calculated by the temperature calculation unit 3 is displayed on a display unit 4, such as a display.

[0037] 4 is a graph showing the indication error when the optimization calculation method is used in the temperature calculation unit 3, and the indication error when the unknowns are eliminated and calculation is performed with one unknown (when the bisection method is used). As can be seen from this graph, even if the sensor noise σ increases, the indication error when the optimization calculation method is used is less affected by the sensor noise σ than the indication error when the bisection method is used, and the temperature can be calculated with high accuracy.

[0038] <Effects of this embodiment> According to the radiation temperature measuring device 100 of this embodiment configured as described above, the amount of infrared light for each of the multiple polarization components for each of the multiple wavelength components is detected, and the temperature of the object to be measured W is calculated based on the detected amounts of at least three types of infrared light. Therefore, the temperature of the object to be measured W can be determined with high accuracy regardless of the infrared light components from the surroundings that are reflected by the object to be measured W.

[0039] In particular, in this embodiment, the temperature calculation unit 3 uses an optimization calculation method that employs a Kalman filter, making it possible to determine the temperature of the object to be measured W while reducing the influence of noise from the infrared sensors 21 and 22. The bisection method, which solves for one unknown, can be changed to a quartering method to solve two unknowns, and to an octupling method to solve three unknowns. However, the amount of calculation increases exponentially, resulting in a long calculation time. On the other hand, Kalman filters such as the unscented Kalman filter can perform calculations quickly even with three unknowns.

[0040] <Other Embodiments> For example, in the above embodiment, four infrared sensors 21, 22 (two first infrared sensors 21a, 21b and two second infrared sensors 22a, 22b) are used to simultaneously detect four types of infrared radiation amounts. However, as shown in FIG. 5 , two infrared sensors 21, 22 (one first infrared sensor 21 and one second infrared sensor 22) may be used to intermittently detect four types of infrared radiation amounts.

[0041] In this case, the polarizer 23 may be common to the two infrared sensors 21, 22 and provided in front of the condenser lens 24 or between the condenser lens 24 and the beam splitter 25. The polarizer 23 may be rotated by a rotation mechanism 26 to switch between a state in which s-polarized light is extracted and a state in which p-polarized light is extracted. When the polarizer 23 is continuously rotated by the rotation mechanism 26, the amount of s-polarized infrared light and the amount of p-polarized infrared light may be detected from the output signals from the infrared sensors 21, 22 using a lock-in detection unit (not shown).

[0042] The optical configuration of the above embodiment is capable of simultaneously measuring the amount of p-polarized infrared light and the amount of s-polarized infrared light, and has good responsiveness, but the amount of infrared light is reduced by the beam splitter 25. Furthermore, the optical configuration shown in Fig. 5 can suppress the reduction in the amount of infrared light, but requires the polarizer 23 to be rotated, which doubles the sampling rate. A configuration shown in Fig. 6 can be considered to solve these problems all at once.

[0043] The infrared detection unit 2 shown in FIG. 6 includes a polarizer 20 that is positioned at an angle of 20 to 65 degrees relative to the incident infrared light, transmits either p-polarized or s-polarized infrared light (here, s-polarized light) and reflects the other p-polarized or s-polarized infrared light (here, p-polarized light). The polarizer 20 is positioned at an angle of 20 to 65 degrees, more preferably 40 to 50 degrees, and even more preferably 45 degrees, relative to the incident infrared light. However, any design that can separate the reflected and transmitted s-polarized and p-polarized light is sufficient. The polarizer 20 may be a wire-grid polarizer or a polarizer other than a wire-grid polarizer. In this case, the direction in which the grid of the polarizer 20 extends (grid direction) is perpendicular to the rotation axis of the polarizer 20. Note that when the grid direction of the polarizer 20 is parallel to the rotation axis of the polarizer 20, p-polarized light is transmitted and s-polarized light is reflected. The extinction ratio of the polarizer 20 is 1:4 to 1:100.

[0044] The first infrared sensor 21 detects the first wavelength λ of either p-polarized or s-polarized light that has passed through the polarizer 20. １ and a first transmission infrared sensor 211 for detecting the amount of infrared light of the first wavelength λ of the other of the p-polarized light and the s-polarized light reflected by the polarizer 20. １ and a first reflective infrared sensor 212 for detecting the amount of infrared light.

[0045] The second infrared sensor 22 detects a second wavelength λ of either p-polarized or s-polarized light that has passed through the polarizer 20. ２ and a second transmission infrared sensor 221 that detects the amount of infrared light of the second wavelength λ of the other of the p-polarized light and the s-polarized light reflected by the polarizer 20. ２ and a second reflective infrared sensor 222 for detecting the amount of infrared light.

[0046] Here, in front of the first transmissive infrared sensor 211 and the second transmissive infrared sensor 221, a first wavelength λ １ or the second wavelength λ ２ (here, the first wavelength λ １ ) and transmits the other (here, the second wavelength λ ２) in the reflected p-polarized light. １ or the second wavelength λ ２ (here, the first wavelength λ １ ) and transmits the other (here, the second wavelength λ ２ ) is provided as a beam splitter 252 such as a dichroic mirror.

[0047] 6, by using the polarizer 20 as a beam splitter, a half mirror is not required, and the amount of s-polarized infrared light and the amount of p-polarized infrared light can be measured simultaneously without reducing the amount of infrared light. Also, by separating the s-polarized light and the p-polarized light with the first mirror in the infrared detection unit 2, it is possible to design dichroic mirrors 251 and 252 dedicated to each polarization, which eliminates the difference in cut-on wavelength due to the difference between s-polarized light and p-polarized light and also increases the transmittance.

[0048] Furthermore, although the temperature calculation unit 3 in the above embodiment calculates the temperature of the measurement object W using four relational expressions, it may also use three or five or more relational expressions to calculate the temperature of the measurement object W. Here, the five or more relational expressions may, in addition to those in the above embodiment, include an amount of s-polarized or p-polarized infrared light at a third wavelength, or may include an amount of infrared light at a polarization angle different from that of s-polarized or p-polarized light at the first or second wavelength.

[0049] In the above embodiment, the temperature of the object to be measured is calculated (using four relational expressions) based on the amount of s-polarized infrared light and the amount of p-polarized infrared light of the first wavelength, and the amount of s-polarized infrared light and the amount of p-polarized infrared light of the second wavelength. However, the temperature of the object to be measured may also be calculated (using three relational expressions) based on the amount of s-polarized infrared light and the amount of p-polarized infrared light of one of the first wavelength or the second wavelength, and the amount of infrared light before polarization of the other of the first wavelength or the second wavelength (amount of infrared light that is a mixture of s-polarized and p-polarized light).

[0050] Furthermore, although the temperature calculation unit 3 in the above embodiment calculates the temperature using an optimization calculation method, it may be configured to calculate the temperature by eliminating unknowns from three or more relational expressions.

[0051] The radiation temperature measuring device 100 in the above embodiment is configured to combine the wavelength differential method and the polarization differential method, but it may also be configured to combine the angle differential method and the polarization differential method, as shown in Fig. 7. Specifically, the radiation temperature measuring device 100 includes an infrared detection unit 2 that detects the amount of infrared light for one or more polarization components for each of the multiple measurement optical axes L1, L2, and a temperature calculation unit 3 that calculates the temperature of the object to be measured based on the amounts of at least three types of infrared light detected by the infrared detection unit 2.

[0052] Specifically, the infrared detection unit 2 includes a first infrared detection unit 2a that detects the amount of infrared light along the measurement optical axis L1, and a second infrared detection unit 2b that detects the amount of infrared light along the measurement optical axis L2.

[0053] The first infrared detector 2a detects the amount of p-polarized infrared light and the amount of s-polarized infrared light along the measurement optical axis L1, while the second infrared detector 2b detects the amount of p-polarized infrared light and the amount of s-polarized infrared light along the measurement optical axis L2.

[0054] Specifically, the first infrared detection unit 2a has two first infrared sensors 21, a polarizer 23a that extracts s-polarized light is provided in front of one first infrared sensor 21a, and a polarizer 23b that extracts p-polarized light is provided in front of the other first infrared sensor 21b. In addition, the first infrared detection unit 2a also has a condenser lens 24 that collects the infrared light, and beam splitters 26a and 26b such as dichroic mirrors that split the infrared light and reflect the other light.

[0055] The second infrared detection unit 2b has two second infrared sensors 22, with a polarizer 23c for extracting s-polarized light provided in front of one second infrared sensor 22a, and a polarizer 23d for extracting p-polarized light provided in front of the other second infrared sensor 22b. The second infrared detection unit 2b also has a condenser lens 24 for collecting infrared light and a beam splitter 26b such as a dichroic mirror for splitting the infrared light and reflecting the other light.

[0056] The temperature calculation unit 3 calculates the temperature of the measurement object W based on the amount of at least three types of infrared rays detected by the infrared detection unit 2. In this embodiment, the amount of s-polarized infrared rays E Ｌ１,ｓ , the amount of p-polarized infrared light E Ｌ１,ｐ , the amount of s-polarized infrared light E Ｌ２,ｓ , and the amount of p-polarized infrared light E of the measurement optical axis L2 Ｌ２,ｐ The temperature of the object W to be measured is calculated based on the above. The calculation method is the same as in the above embodiment.

[0057] 7, the first infrared detection unit 2a has two infrared sensors 21a, 21b and polarizers 23a, 23b provided in front of them, but a single infrared sensor 21 may also be used. In this case, it is conceivable to provide a single polarizer 23 in front of the infrared sensor 21 and rotate the polarizer 23 using a rotation mechanism 26 to switch between a state in which s-polarized light is extracted and a state in which p-polarized light is extracted. Furthermore, when the polarizer 23 is continuously rotated by the rotation mechanism 26, it is conceivable to detect the amount of s-polarized infrared light and the amount of p-polarized infrared light on the measurement optical axis L1 using a lock-in detection unit (not shown) from the output signal from the infrared sensor 21.

[0058] 7, the second infrared detection unit 2b has two infrared sensors 22a and 22b, and polarizers 23c and 23d are provided in front of them, but a single infrared sensor 22 may be used. In this case, it is conceivable to provide a single polarizer 23 in front of the infrared sensor 22 and rotate the polarizer 23 using a rotation mechanism 26 to switch between a state in which s-polarized light is extracted and a state in which p-polarized light is extracted. Furthermore, when the polarizer 23 is continuously rotated by the rotation mechanism 26, it is conceivable to detect the amount of s-polarized infrared light and the amount of p-polarized infrared light on the measurement optical axis L2 using a lock-in detection unit (not shown) from the output signal from the infrared sensor 21.

[0059] Another radiation thermometer 100 measures the temperature of a measurement object, such as a metal, by detecting infrared rays emitted from the measurement object. As shown in FIG. 8 , the radiation thermometer 100 may include an infrared detector 2 that detects the amount of infrared rays for each of a plurality of polarization components (e.g., s-polarized and p-polarized components) and a temperature calculator 3 that calculates the temperature of the measurement object based on the amount of at least two types of infrared rays (e.g., the amount of s-polarized infrared rays and the amount of p-polarized infrared rays) detected by the infrared detector 2. In this case, the infrared detector 2 detects the amount of p-polarized infrared rays and the amount of s-polarized infrared rays along the measurement optical axis L. Specifically, the infrared detector 2 includes two infrared sensors 21. A polarizer 23a for extracting s-polarized light is provided in front of one infrared sensor 21a, and a polarizer 23b for extracting p-polarized light is provided in front of the other infrared sensor 21b. The infrared detector 2 also includes a condenser lens 24 that collects the infrared rays and a beam splitter 25, such as a dichroic mirror, that splits the infrared rays and reflects the other. The temperature calculation unit 3 calculates the temperature of the measurement object W based on the amount of at least two types of infrared rays detected by the infrared detection unit 2. In this embodiment, the amount of s-polarized infrared rays E Ｌ,ｓ , and the amount of p-polarized infrared light E of the measurement optical axis L Ｌ,ｐ The temperature of the object W to be measured is calculated based on the above. The calculation method is the same as in the above embodiment.

[0060] In the above embodiment, the infrared sensors 21 and 22 each include a thermopile element, but this is not limiting. The sensor element used as each of the infrared sensors 21 and 22 may be any suitable sensor element depending on the temperature range to be measured.

[0061] For example, when the radiation thermometer 100 is used in a dry etching apparatus or the like, the upper limit of the measurement temperature range is approximately 200° C. As can be seen from Planck's law, it is common to use the long-wavelength infrared region in order to ensure sensitivity in such a low-temperature range. In such cases, it is preferable to use a thermopile sensor or a quantum sensor such as an InAsSb sensor as each of the infrared sensors 21 and 22.

[0062] Furthermore, when the radiation thermometer 100 is used in a film forming apparatus such as a CVD apparatus or an ashing apparatus, the upper limit of the measurement temperature range is approximately 700° C., which makes it possible to use the visible light region, near-infrared region, and mid-infrared region in addition to the long-wavelength infrared region. Therefore, in such a case, not only a thermopile sensor or a quantum sensor such as an InAsSb sensor, but also an InGaAs sensor or the like can be used as each of the infrared sensors 21 and 22.

[0063] The infrared sensors 21 and 22 may be made of the same type of sensor element, or may be made of different types of sensor elements.

[0064] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention.

[0065] According to the present invention, in a wavelength differential type radiation temperature measuring device, the temperature of an object to be measured can be determined with high accuracy regardless of infrared components from the surroundings that are reflected by the object to be measured.

[0066] 100: Radiation temperature measuring device W: Measurement object 2: Infrared detection unit 21 (21a, 21b): First infrared sensor 22 (22a, 22b): Second infrared sensor 23 (23a to 24d): Polarizer 3: Temperature calculation unit

Claims

1. A radiation thermometer that detects infrared rays emitted from a measurement object and measures the temperature of the measurement object, comprising: an infrared detector that detects the amount of infrared rays for each of a plurality of wavelength components and detects the amount of infrared rays for each of a plurality of polarization components in at least one of the plurality of wavelength components; and a temperature calculator that calculates the temperature of the measurement object based on the amount of at least three types of infrared rays detected by the infrared detector.

2. The radiation temperature measuring device according to claim 1, wherein the infrared detection unit has a first infrared sensor that detects the amount of infrared radiation at a first wavelength, and a second infrared sensor that detects the amount of infrared radiation at a second wavelength different from the first wavelength.

3. The radiation temperature measuring device according to claim 2, wherein the infrared detection unit further comprises polarizers provided in front of the first infrared sensor and the second infrared sensor, the first infrared sensor detects the amount of infrared light for each of the two different polarized components of the first wavelength, and the second infrared sensor detects the amount of infrared light for each of the two different polarized components of the second wavelength.

4. The radiation temperature measuring device according to claim 3, wherein the first infrared sensor detects the amount of p-polarized infrared light of the first wavelength and the amount of s-polarized infrared light of the first wavelength, and the second infrared sensor detects the amount of p-polarized infrared light of the second wavelength and the amount of s-polarized infrared light of the second wavelength.

5. The radiation temperature measuring device according to claim 2, wherein the infrared detection unit is arranged at an angle of 20 to 65 degrees with respect to the incident infrared light, and further comprises a polarizer that transmits either p-polarized or s-polarized infrared light and reflects the other of the p-polarized or s-polarized infrared light; the first infrared sensor comprises a first transmission infrared sensor that detects the amount of either p-polarized or s-polarized infrared light of the first wavelength that has transmitted through the polarizer, and a first reflection infrared sensor that detects the amount of the other of p-polarized or s-polarized infrared light of the first wavelength that has reflected off the polarizer; and the second infrared sensor comprises a second transmission infrared sensor that detects the amount of either p-polarized or s-polarized infrared light of the second wavelength that has transmitted through the polarizer, and a second reflection infrared sensor that detects the amount of the other of p-polarized or s-polarized infrared light of the second wavelength that has reflected off the polarizer.

6. A radiation temperature measuring device according to any one of claims 1 to 5, wherein the infrared detection unit detects the amount of infrared radiation at a position inclined with respect to the surface of the measurement object.

7. A radiation temperature measuring device according to claim 6, wherein the infrared detection unit detects the amount of infrared radiation at a position inclined so that the angle formed with the surface of the measurement object is the Brewster angle.

8. A radiation temperature measuring device as claimed in any one of claims 1 to 7, wherein the temperature calculation unit calculates the temperature of the object to be measured using an optimization calculation method from the amount of at least three types of infrared rays detected by the infrared detection unit.

9. The radiation temperature measuring device according to claim 8, wherein the temperature calculation unit calculates the background temperature of the measurement object and / or the ambient temperature of the measurement object in addition to the temperature of the measurement object.

10. A radiation temperature measuring device according to claim 8 or 9, wherein the temperature calculation unit calculates the temperature of the object to be measured using a Kalman filter from the amount of at least three types of infrared radiation detected by the infrared detection unit.

11. A radiation temperature measurement method for detecting infrared rays emitted from an object to be measured and measuring the temperature of said object, comprising: detecting the amount of infrared rays for each of a plurality of wavelength components; detecting the amount of infrared rays for each of a plurality of polarization components for at least one of said plurality of wavelength components; and calculating the temperature of said object based on the detected amounts of at least three types of infrared rays.

12. A radiation temperature measurement program used in a radiation temperature measurement device that has an infrared detection unit that detects the amount of infrared light for each of multiple wavelength components in infrared light emitted from a measurement object and detects the amount of infrared light for each of multiple polarization components in at least one of the multiple wavelength components, and that causes a computer to function as a temperature calculation unit that calculates the temperature of the measurement object based on the amount of at least three types of infrared light detected by the infrared detection unit.

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