Non-contact temperature measuring device and non-contact temperature measuring method

Abstract

This non-contact temperature measuring device comprises: a light emitting unit (light source (18a)) that emits measurement light (L1) toward a front surface (Wa) of a measured object; a light receiving unit (light receiving sensor (18b)) that receives reflected light (L2A) of the measurement light (L1) reflected by the front surface (Wa) and reflected light (L2B) of the measurement light (L1) reflected by a rear surface (Wb) on the opposite side to the front surface (Wa), and outputs a light reception signal; a thickness calculating unit (18c) that calculates a second thickness on the basis of the light reception signal output from the light receiving unit, where the actual thickness of the measured object is defined as a first thickness (thickness (Lv)), and a thickness obtained by multiplying the first thickness by the refractive index of the measured object is defined as the second thickness (Lopt)); a measured object information acquiring unit (wafer information acquiring unit (34)) that acquires measured object information (wafer information (29)); and a temperature calculating unit (36) that calculates the temperature of the measured object on the basis of the second thickness and the measured object information.

Description

Non-contact temperature measuring device and non-contact temperature measuring method

[0001] The present invention relates to a non-contact temperature measuring device and a non-contact temperature measuring method for measuring the temperature of an optically transparent object without contact.

[0002] In semiconductor manufacturing processes for manufacturing wafers of silicon (Si), silicon carbide (SiC), gallium nitride (GaN), or the like, it is necessary to accurately measure and control various parameters during the semiconductor manufacturing process, particularly wafer temperature, in order to improve wafer quality and yield (see Patent Documents 1 and 2, and Non-Patent Documents 1 and 2).

[0003] Known methods for measuring the temperature of a wafer (object to be measured) include, for example, a method using an electric thermometer (such as a thermocouple, thermistor, or platinum resistance thermometer), a method using a radiation thermometer, and a method using a fluorescent optical fiber thermometer.

[0004] JP 2018-073962 A JP 2020-077864 A

[0005] Kenji Ishikawa and 1 other author, "The cutting edge of ultra-dry etching technology for realizing advanced device structures," [online], J. Plasma Fusion Res. Vol. 97, No. 9 (2021) 508-510, [Retrieved December 27, 2023], Internet <URL: https: / / www.jspf.or.jp / Journal / PDF_JSPF / jspf2021_09 / 9709SPall.pdf> Toru Iuchi, "In situ temperature measurement of silicon semiconductor wafers," [online], Instrumentation and Control, Vol. 47, No. 5, May 2008, [Retrieved December 27, 2023], Internet <URL: https: / / www.jstage.jst.go.jp / article / sicejl / 47 / 5 / 47_395 / _pdf>

[0006] However, when measuring the wafer temperature using an electric thermometer, the electric thermometer must be brought into contact with the wafer, which increases the operator's workload and may increase measurement errors due to the effects of electromagnetic interference, high magnetic fields, or high voltages on the lead wires of the electric thermometer.

[0007] When measuring the temperature of a wafer using a radiation thermometer, there is a problem that an error occurs in the temperature measurement results if there is a source of infrared rays, such as plasma, around the wafer.

[0008] Although fluorescent fiber optic thermometers are resistant to electrical, magnetic, and mechanical noise, they require a fluorescent material to be in contact with the wafer, which means that temperature measurement using a fluorescent fiber optic thermometer is not completely non-contact, and this increases the operator's workload.

[0009] The present invention has been made in view of the above circumstances, and has an object to provide a non-contact temperature measuring device and a non-contact temperature measuring method that are capable of measuring the temperature of an object to be measured simply and with high accuracy.

[0010] A non-contact temperature measuring device for achieving the object of the present invention is a non-contact temperature measuring device that measures the temperature of a light-transmitting object to be measured without contact, having a front surface and a back surface, and is equipped with: a light emitting unit that emits measurement light toward the front surface; a light receiving unit that receives reflected light of the measurement light reflected by the front surface and reflected light of the measurement light that passes through the inside of the object to be measured from the front surface and is reflected by the back surface opposite the front surface of the object to be measured, and outputs a light receiving signal; a thickness calculation unit that calculates a second thickness based on the light receiving signal output from the light receiving unit, where the actual thickness of the object to be measured is defined as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is defined as a second thickness; a measurand information acquisition unit that acquires measurand information including the first thickness, the refractive index, and the refractive index temperature coefficient of the object to be measured; and a temperature calculation unit that calculates the temperature of the object to be measured based on the second thickness calculated by the thickness calculation unit and the measurand information acquired by the measurand information acquisition unit.

[0011] According to this non-contact temperature measuring device, the temperature of the object can be measured non-contact based on the measurement result of the second thickness of the object.

[0012] In a non-contact temperature measurement device according to another aspect of the present invention, the object information acquisition unit acquires object information including the first thickness, refractive index, refractive index temperature coefficient, and linear thermal expansion coefficient of the object, thereby enabling non-contact measurement of the temperature of the object based on the measurement result of non-contact measurement of the second thickness of the object.

[0013] In a non-contact temperature measuring device according to another aspect of the present invention, the light emitting unit emits measurement light of multiple wavelengths toward the surface, the light receiving unit receives reflected light for each wavelength and outputs a light receiving signal, the thickness calculation unit calculates a second thickness for each wavelength based on the light receiving signal for each wavelength output from the light receiving unit, and the temperature calculation unit calculates the temperature of the object to be measured based on the second thickness for each wavelength calculated by the thickness calculation unit and information about the object to be measured.

[0014] A non-contact temperature measuring device for achieving the object of the present invention is a non-contact temperature measuring device that measures the temperature of a light-transmitting object to be measured without contact, the non-contact temperature measuring device being configured to include: a light emitting unit that emits measurement light toward the surface; a light receiving unit that receives reflected light of the measurement light reflected by the surface and reflected light of the measurement light that passes through the interior of the object from the surface and is reflected by the back surface of the object opposite the surface, and outputs a light receiving signal; a thickness calculation unit that calculates a second thickness based on the light receiving signal output from the light receiving unit, where the actual thickness of the object to be measured is defined as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is defined as a second thickness; a correlation data acquisition unit that acquires correlation data in advance showing the correlation between the second thickness and the temperature of the object to be measured; and a temperature calculation unit that calculates the temperature of the object to be measured by referring to the correlation data acquired by the correlation data acquisition unit, based on the second thickness calculated by the thickness calculation unit.

[0015] According to this non-contact temperature measuring device, the temperature of the object can be measured non-contact based on the measurement result of the second thickness of the object.

[0016] A non-contact temperature measurement method for achieving the object of the present invention is a non-contact temperature measurement method for non-contactly measuring the temperature of a light-transmitting object having a front surface and a back surface, the non-contact temperature measurement method comprising: a light emitting step of emitting measurement light toward the front surface; a light receiving step of receiving reflected light of the measurement light reflected by the front surface and reflected light of the measurement light that has passed through the interior of the object from the front surface and is reflected by the back surface opposite the front surface of the object, and outputting a light receiving signal; a thickness calculation step of calculating a second thickness based on the light receiving signal output in the light receiving step, where the actual thickness of the object is defined as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is defined as a second thickness; a measurand information acquisition step of acquiring measurand information including the first thickness, the refractive index, and the refractive index temperature coefficient of the object; and a temperature calculation step of calculating the temperature of the object based on the second thickness calculated in the thickness calculation step and the measurand information acquired in the measurand information acquisition step.

[0017] A non-contact temperature measurement method for achieving the object of the present invention is a non-contact temperature measurement method for non-contactly measuring the temperature of a light-transmitting object having a front surface and a back surface, the method comprising: a light emitting step of emitting measurement light toward the front surface; a light receiving step of receiving reflected light of the measurement light reflected by the front surface and reflected light of the measurement light that has passed through the interior of the object from the front surface and is reflected by the back surface opposite the front surface of the object, and outputting a light receiving signal; a thickness calculation step of calculating a second thickness based on the light receiving signal output in the light receiving step, where the actual thickness of the object is defined as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is defined as a second thickness; a correlation data acquisition step of previously acquiring correlation data showing the correlation between the second thickness and the temperature of the object; and a temperature calculation step of calculating the temperature of the object based on the second thickness calculated in the thickness calculation step and by referring to the correlation data acquired in the correlation data acquisition step.

[0018] The present invention makes it possible to measure the temperature of an object to be measured simply and with high accuracy.

[0019] 1 is a schematic diagram of a non-contact temperature measuring device according to a first embodiment; FIG. 2 is an explanatory diagram for explaining measurement light emitted from a sensor head and reflected light incident on the sensor head; FIG. 3 is a functional block diagram of a control device according to a first embodiment; ｏｐｔ and temperature change ΔT. FIG. 4 is a graph showing the error between the graph indicated by reference numeral 4A in FIG. 4 and the graph indicated by reference numeral 4B in FIG. 4. FIG. 5 is a flowchart showing the flow of a non-contact temperature measurement method for a wafer using the non-contact temperature measurement device of the first embodiment. FIG. 6 is a schematic diagram of a non-contact temperature measurement device of the second embodiment. FIG. 7 is a functional block diagram of a control device of the second embodiment. FIG. 8 is a schematic diagram of a non-contact temperature measurement device of the third embodiment. FIG. 9 is an explanatory diagram for explaining an example of a method for generating correlation data. FIG. 10 is a diagram showing an example of recorded data recorded by a data logger. FIG. 11 is a diagram showing an example of correlation data. FIG. 12 is a flowchart showing the flow of a non-contact temperature measurement method for a wafer using the non-contact temperature measurement device of the third embodiment.

[0020] 1 is a schematic diagram of a non-contact temperature measurement device 10 according to a first embodiment of the present invention. The non-contact temperature measurement device 10 is used in a semiconductor manufacturing process for manufacturing various types of wafers W, such as silicon wafers, and performs non-contact measurement of the wafer temperature of the wafer W. The wafer W corresponds to the object to be measured in the present invention and is optically transparent. For example, if the wafer W is a silicon wafer, the wafer W is substantially transparent to light with a wavelength of 1.2 μm to 6 μm.

[0021] The non-contact temperature measuring device 10 includes a thickness measuring device 12 and a computer 20. Note that the functions of the computer 20, which will be described later, may be provided in the thickness measuring device 12 (thickness measuring device main body 18). In this case, the thickness measuring device 12 alone also functions as the non-contact temperature measuring device 10.

[0022] The thickness measuring device 12 optically and non-contactly measures the thickness of the wafer W. Examples of the thickness measuring device 12 include a wavelength swept laser interferometer, an interferometer using spectroscopic interferometry (SS-OCT: Swept Source Optical Coherence Tomography), and an interferometer using vertical scanning low coherence interferometry (CSI: Coherence Scanning Interferometry, TD (Time-domain)-OCT).

[0023] The thickness gauge 12 is composed of, for example, a sensor head 14, an optical fiber cable 16, and a thickness gauge main body 18. The configuration of the thickness gauge 12 can be changed as appropriate as long as it can optically measure the thickness of the wafer W in a non-contact manner.

[0024] 2 is an explanatory diagram illustrating the measurement light L1 emitted from the sensor head 14 and the reflected light L2 incident on the sensor head 14. As shown in FIG. 2 and the above-described FIG. 1, the sensor head 14 corresponds to the light emitting unit of the present invention and is disposed at a position facing the front surface Wa of the wafer W. Here, the front surface Wa is an opposing surface facing the sensor head 14 and is an incident surface onto which the measurement light L1 from the sensor head 14 is incident. The back surface Wb of the wafer W is the surface opposite the front surface Wa of the wafer W.

[0025] The sensor head 14 is optically connected to a thickness measuring device main body 18 via an optical fiber cable 16, and emits measurement light L1 incident from the thickness measuring device main body 18 toward the surface Wa. The measurement light L1 is light of a wavelength (wavelength range) that is transmitted through the wafer W.

[0026] A portion of the measurement light L1 incident on the front surface Wa from the sensor head 14 is reflected from the front surface Wa toward the sensor head 14 as reflected light L2A, and the remainder is transmitted through the interior of the wafer W to reach the back surface Wb of the wafer W. For example, if the wafer W is a silicon wafer [refractive index: 3.483 (wavelength of the measurement light L1: 1.5 μm), temperature coefficient: 1.8×10 －４ ], 27% of the measurement light L1 becomes the reflected light L2A.

[0027] Part of the measurement light L1 that reaches the back surface Wb is reflected from the back surface Wb toward the front surface Wa as reflected light L2B, and the remainder is emitted from the back surface Wb to the outside of the wafer W. Then, part of the reflected light L2B reflected toward the front surface Wa is emitted from the front surface Wa toward the sensor head 14, and the remainder is reflected again from the front surface Wa toward the back surface Wb.

[0028] In addition, when the wafer W is the silicon wafer described above, the measurement light L1 emitted from the back surface Wb to the outside of the wafer W is 53% of the original measurement light L1, and the reflected light L2B emitted from the front surface Wa toward the sensor head 14 is 14% of the original measurement light L1.

[0029] Reflected light L2, which includes reflected light L2A reflected from the front surface Wa and reflected light L2B reflected from the back surface Wb, is incident on the sensor head 14. The reflected light L2 incident on the sensor head 14 is incident on the thickness measuring device main body 18 via the optical fiber cable 16.

[0030] Returning to FIG. 1, the thickness measuring device main body 18 includes a light source 18a, a light receiving sensor 18b, and a thickness calculation unit 18c.

[0031] The light source 18a emits measurement light L1 to the optical fiber cable 16. As a result, the measurement light L1 is incident on the sensor head 14 via the optical fiber cable 16, and the measurement light L1 is emitted from the sensor head 14 toward the surface Wa. The light-receiving sensor 18b corresponds to the light-receiving unit of the present invention, and receives reflected light L2 incident from the sensor head 14 via the optical fiber cable 16 and outputs a light-receiving signal. The light source 18a and the light-receiving sensor 18b may be provided in the sensor head 14.

[0032] The thickness calculation unit 18c calculates the thickness L of the wafer W based on the light receiving signal output from the light receiving sensor 18b. ｏｐｔ (corresponding to the second thickness of the present invention) is calculated, and this thickness L ｏｐｔ The calculation result is output to the computer 20. The thickness L measured by the wavelength sweep laser interferometer, the interferometer using spectroscopic interferometry, and the interferometer using vertical scanning low coherence interferometry is ｏｐｔThe calculation method for the thickness L of the wafer W calculated by the thickness calculation unit 18c is a known technique, and therefore a detailed description thereof will be omitted here. ｏｐｔ is the actual thickness L of the wafer W ｖ (corresponding to the first thickness of the present invention) multiplied by the refractive index of the wafer W, so the actual thickness L ｖ is different.

[0033] The thickness calculation unit 18c may be provided in a control device 22 (see FIG. 3) of the computer 20, which will be described later. In this case, the light receiving sensor 18b outputs a light receiving signal of the reflected light L2 to the control device 22.

[0034] The computer 20 includes a control device 22, an operation unit 24, and a display unit 26. Note that the computer 20 may be replaced by various known arithmetic units.

[0035] The control device 22 controls the thickness measurement of the wafer W by the thickness measuring device 12 (emission of the measurement light L1, reception of the reflected light L2, and measurement of the thickness L ｏｐｔ The control device 22 controls the thickness measurement device 18, the operation unit 24, and the display unit 26.

[0036] The operation unit 24 accepts various operations of the non-contact temperature measuring device 10, such as an operation to start measuring the temperature of the wafer W. The operation unit 24 includes various operation devices such as a mouse, a keyboard, and operation buttons.

[0037] The display unit 26 is, for example, a liquid crystal display, and displays various setting screens of the non-contact temperature measuring device 10, measurement results of the wafer temperature, and the like.

[0038] FIG. 3 is a functional block diagram of the control device 22 according to the first embodiment. As shown in FIG. 3, the control device 22 includes an arithmetic circuit configured with various processors, memories, and the like. The various processors include a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), and a programmable logic device (e.g., a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). The various functions of the control device 22 may be implemented by a single processor or by multiple processors of the same or different types.

[0039] In addition to the thickness measuring instrument main body 18, the operation unit 24, and the display unit 26, a storage unit 28 is connected to the control device 22. The storage unit 28 may be built into the control device 22. In addition to a control program (not shown) for the control device 22, the storage unit 28 stores wafer information 29, which corresponds to the object to be measured information of the present invention, for each type of wafer W in advance.

[0040] The wafer information 29 is information relating to the actual size, properties, characteristics, etc. of the material (silicon, etc.) of the wafer W, and is information used for calculating the wafer temperature by the control device 22 (temperature calculation unit 36) described later. Specifically, the wafer information 29 includes the actual thickness L of the wafer W measured by a method other than the method using the thickness gauge 12. ｖ and the refractive index n and refractive index temperature coefficient Δn of the known wafer W. ｔ and the coefficient of linear thermal expansion α.

[0041] The control device 22 executes a control program (not shown) stored in the storage unit 28 to function as a measurement control unit 30, a thickness acquisition unit 32, a wafer information acquisition unit 34, and a temperature calculation unit 36.

[0042] The measurement control unit 30 operates in response to a temperature measurement start operation input to the operation unit 24, and causes the thickness measuring device 12 to measure the thickness of the wafer W. Specifically, the measurement control unit 30 controls the emission of measurement light L1 from the light source 18a, the reception of reflected light L2 by the light receiving sensor 18b and the output of a light reception signal, and the calculation of the thickness L by the thickness calculation unit 18c. ｏｐｔ Calculation and are performed.

[0043] The thickness acquisition unit 32 is configured to acquire the thickness L ｏｐｔ When the calculation of the thickness L is performed, the thickness calculation unit 18c outputs the thickness L ｏｐｔ and outputs the calculation result to the temperature calculation unit 36.

[0044] Wafer information acquisition unit 34 corresponds to the object to be measured information acquisition unit of the present invention. Wafer information acquisition unit 34 operates, for example, in response to input of a temperature measurement start operation, acquires wafer information 29 from storage unit 28, and outputs this wafer information 29 to temperature calculation unit 36. Note that instead of acquiring wafer information 29 from storage unit 28, wafer information acquisition unit 34 may acquire wafer information 29 from an external server via a known communication network.

[0045] The temperature calculation unit 36 ​​calculates the thickness L input from the thickness acquisition unit 32. ｏｐｔ and the wafer information 29 input from the wafer information acquisition unit 34. An example of the calculation of the wafer temperature by the temperature calculation unit 36 ​​will now be described in detail.

[0046] As mentioned above, the thickness L of the wafer W ｏｐｔ is the actual thickness L ｖ is the thickness obtained by multiplying the refractive index n of the wafer W. Therefore, the actual thickness L ｖ is expressed by the following formula (1).

[0047]

[0048] Here, the refractive index n has temperature dependency, and this temperature dependency is called the "refractive index temperature coefficient Δn ｔ Also, the actual thickness L ｖThere is a temperature dependency on the temperature coefficient α, which is known as the "linear thermal expansion coefficient α." Therefore, when the temperature change of the wafer W from a predetermined reference temperature T is defined as ΔT, the above [Equation 1] can be expressed as the following [Equation 2].

[0049]

[0050] In the above formula (2), the refractive index n at the reference temperature T and the refractive index temperature coefficient Δn ｔ is a parameter related to the material of the wafer W and is therefore a known value. The linear thermal expansion coefficient α is also a parameter related to the material of the wafer W and is therefore also a known value. ｖ , refractive index n, refractive index temperature coefficient Δn ｔ and the linear thermal expansion coefficient α) are obtained in advance, ｏｐｔ and wafer information 29, the temperature change ΔT can be derived as shown in the following [Equation 3]. Then, the wafer temperature can be calculated based on the derived temperature change ΔT and a known reference temperature T.

[0051]

[0052] The temperature calculation unit 36 ​​calculates the thickness L input from the thickness acquisition unit 32. ｏｐｔ Based on the wafer information 29 input from the wafer information acquisition unit 34, the temperature change ΔT is calculated using the above equation (3), and the wafer temperature is calculated based on this temperature change ΔT and a known reference temperature T.

[0053] In the above formula (3), the refractive index temperature coefficient Δn ｔ is approximately 100 times the linear thermal expansion coefficient α. Therefore, depending on the desired precision of the wafer temperature, the linear thermal expansion coefficient α can be simplified to α = 0.0. In this case, the above [Equation 3] is simplified as shown in the following [Equation 4].

[0054]

[0055] FIG. 4 shows that the wafer W is made of silicon (refractive index n=3.4, refractive index temperature coefficient Δn ｔ = 2.0 × 10 －４ and the actual thickness L ｖ= 0.777 mm), the thickness L ｏｐｔ 4 is a graph showing the relationship between the linear thermal expansion coefficient α and the temperature change ΔT. －６ " Thickness L ｏｐｔ The graph indicated by reference numeral 4B in FIG. 4 shows the relationship between the thickness L and the temperature change ΔT when the linear thermal expansion coefficient α is simplified to "α=0.0". ｏｐｔ and temperature change ΔT.

[0056] FIG. 5 is a graph showing the error between the graph 4A in FIG. 4 and the graph 4B in FIG.

[0057] 4 and 5, there is only a small difference between the case where the linear thermal expansion coefficient α is simplified to "α = 0.0" and the case where it is not simplified, so it has been confirmed that simplifying the linear thermal expansion coefficient α does not pose a problem depending on the accuracy of the desired wafer temperature. In this case, the calculation of the temperature change ΔT by the temperature calculation unit 36 ​​is simplified, and the time required to calculate the wafer temperature is shortened.

[0058] 6 is a flowchart showing the flow of the non-contact temperature measurement method for the wafer W by the non-contact temperature measurement device 10 of the first embodiment. It is assumed that the wafer information 29 is stored in advance in the storage unit 28.

[0059] 6, when a temperature measurement start operation is input to the operation unit 24 (step S1), the control device 22 functions as the measurement control unit 30, the thickness acquisition unit 32, the wafer information acquisition unit 34, and the temperature calculation unit 36. Then, the measurement control unit 30 causes the thickness measurement device 12 to measure the thickness of the wafer W. As a result, the light source 18a emits measurement light L1, which is then emitted from the sensor head 14 via the optical fiber cable 16 toward the front surface Wa of the wafer W (step S2, which corresponds to the light emission step of the present invention).

[0060] When the measurement light L1 is emitted from the sensor head 14 toward the front surface Wa, reflected light L2, which includes reflected light L2A reflected from the front surface Wa and reflected light L2B reflected from the back surface Wb, is incident on the sensor head 14. The reflected light L2 incident on the sensor head 14 is incident on the light-receiving sensor 18b via the optical fiber cable 16. This causes the light-receiving sensor 18b to receive the reflected light L2 and output a light-receiving signal (step S3, which corresponds to the light-receiving step of the present invention).

[0061] Next, the thickness calculation unit 18c calculates the thickness L of the wafer W based on the light receiving signal output from the light receiving sensor 18b. ｏｐｔ The calculation result is output to the temperature calculation unit 36 ​​(step S4, which corresponds to the thickness calculation step of the present invention). ｏｐｔ is measured non-contact.

[0062] Meanwhile, in response to input of a temperature measurement start operation to operation unit 24, wafer information acquisition unit 34 acquires wafer information 29 from storage unit 28 and outputs this wafer information 29 to temperature calculation unit 36 ​​(step S5, which corresponds to a measurement object information acquisition step of the present invention). Note that the timing of acquisition of wafer information 29 by wafer information acquisition unit 34 is not particularly limited as long as it is before the wafer temperature is calculated by temperature calculation unit 36.

[0063] Then, the temperature calculation unit 36 ​​calculates the thickness L ｏｐｔ Based on the wafer information 29 input from the wafer information acquisition unit 34, the temperature change ΔT is calculated using the above [Equation 3] or [Equation 4], and the wafer temperature is calculated based on this temperature change ΔT and the reference temperature T (step S6, corresponding to the temperature calculation step of the present invention).

[0064] As described above, the non-contact temperature measuring device 10 of the first embodiment can measure the temperature of the wafer W having a thickness L ｏｐｔ Since the wafer temperature can be measured simply by contactlessly measuring the temperature of the wafer W, the wafer temperature can be measured without being affected by electrical, magnetic, or mechanical noise, or by plasma that generates infrared rays, etc. As a result, the temperature of the wafer W can be measured simply and with high accuracy.

[0065] [Second embodiment] Fig. 7 is a schematic diagram of a non-contact temperature measuring device 10 of a second embodiment. Fig. 8 is a functional block diagram of a control device 22 of the second embodiment. The non-contact temperature measuring device 10 of the first embodiment measures the wafer temperature in a non-contact manner using a measurement light L1 of a single wavelength. However, the actual thickness L of the wafer W during the semiconductor manufacturing process is measured. ｖ If the wavelength L1 of the measurement light L1 changes significantly, an error may occur in the measurement result of the wafer temperature. Therefore, the non-contact temperature measurement device 10 of the second embodiment performs non-contact measurement of the wafer temperature using measurement light L1 of multiple wavelengths (two wavelengths in this case).

[0066] 7 and 8, the non-contact temperature measuring device 10 of the second embodiment has basically the same configuration as the non-contact temperature measuring device 10 of the first embodiment, except that it includes a thickness measuring device 12A that is different from the thickness measuring device 12 of the first embodiment. Therefore, components that are the same in function or configuration as those of the first embodiment are given the same reference numerals and their description will be omitted.

[0067] The thickness measuring device 12A measures two different wavelengths (wavelengths λ １ , wavelength λ ２ ) to measure the thickness L of the wafer W. ｏｐｔ，λ１ and thickness L ｏｐｔ，λ２ The thickness measuring device 12A includes the sensor head 14 and the optical fiber cable 16, as well as an optical fiber coupler 17 and thickness measuring device main bodies 18-1 and 18-2.

[0068] The optical fiber coupler 17 is, for example, a WDM (Wavelength Division Multiplexing) combiner / splitter. The optical fiber cable 16 (sensor head 14) is connected to one end of the optical fiber coupler 17, and thickness measuring device main bodies 18-1 and 18-2 are connected to the other end. The optical fiber coupler 17 receives the wavelength λ １ and the wavelength λ incident from the thickness measuring instrument main body 18-2 described later. ２The optical fiber coupler 17 combines (multiplexes) the reflected light L2 of two wavelengths incident from the optical fiber cable 16 and outputs it to the optical fiber cable 16 (sensor head 14). １ The reflected light L2 of wavelength λ is emitted to the thickness measuring instrument main body 18-1. ２ The reflected light L2 is emitted to the thickness measuring device main body 18-2.

[0069] The thickness measuring device main bodies 18-1 and 18-2 have basically the same configuration as the thickness measuring device main body 18 of the first embodiment.

[0070] The light source 18a of the thickness measuring device main body 18-1 emits light of wavelength λ １ The light source 18a of the thickness measuring device main body 18-2 emits measuring light L1 of wavelength λ １ different wavelength λ ２ The measuring light L1 having a wavelength λ １ Measurement light L1 and wavelength λ ２ The measuring light L1 is combined by the optical fiber coupler 17, and then enters the sensor head 14 via the optical fiber cable 16, and is emitted from the sensor head 14 toward the surface Wa. １ , wavelength λ ２ ) is incident on the optical fiber coupler 17 via the optical fiber cable 16 from the sensor head 14 and has a wavelength λ １ Reflected light L2 and wavelength λ ２ The reflected light L2 is split into the reflected light L1 and the reflected light L2 of wavelength λ １ The reflected light L2 is emitted from the optical fiber coupler 17 to the thickness measuring device main body 18-1 and has a wavelength λ ２ The reflected light L2 is emitted from the optical fiber coupler 17 to the thickness measuring device main body 18-2.

[0071] The light receiving sensor 18b of the thickness measuring device main body 18-1 receives the wavelength λ １ The thickness calculation unit 18c of the thickness measuring device main body 18-1 receives the reflected light L2 and outputs a light reception signal, and calculates the thickness L of the wafer W based on the light reception signal. ｏｐｔ，λ１ The light receiving sensor 18b of the thickness measuring device main body 18-2 receives the wavelength λ ２The thickness calculator 18c of the thickness measuring device main body 18-2 receives the reflected light L2 and outputs a light receiving signal, and calculates the thickness L of the wafer W based on the light receiving signal. ｏｐｔ，λ２ Calculate the following.

[0072] In response to a temperature measurement start operation input to the operation unit 24, the measurement control unit 30 of the second embodiment controls, for each of the thickness measuring device main bodies 18-1 and 18-2, the emission of measurement light L1 from the light source 18a, the reception of reflected light L2 by the light receiving sensor 18b and the output of a light reception signal, and the calculation of thickness L by the thickness calculation unit 18c. ｏｐｔ，λｋ [K=1, 2]. This allows the thickness L ｏｐｔ，λｋ is measured non-contact.

[0073] The thickness acquisition unit 32 of the second embodiment acquires the thickness L for each wavelength of the measurement light L1 from the thickness measurement device main bodies 18-1 and 18-2. ｏｐｔ，λｋ and outputs these calculation results to the temperature calculation unit 36.

[0074] The temperature calculation unit 36 ​​of the second embodiment calculates the thickness L ｏｐｔ，λｋ and wafer information 29. Then, the temperature calculation unit 36 ​​calculates the wafer temperature based on the temperature change ΔT calculated for each wavelength of the measurement light L1 and the reference temperature T. An example of the calculation of the wafer temperature by the temperature calculation unit 36 ​​of the second embodiment will be specifically described below.

[0075] The refractive index n of the wafer W for each wavelength of the measurement light L1 is expressed as the refractive index n λＫ When [K=1, 2], the thickness L for each wavelength of the measurement light L1 ｏｐｔ，λｋ is the actual thickness L ｖ The refractive index n of the wafer W λＫ Therefore, the actual thickness L ｖ is expressed by the following formula [5].

[0076]

[0077] And the refractive index n λＫ The temperature dependence of the refractive index temperature coefficient Δn ｔ，λＫ When expressed as [K=1, 2], the above [Equation 5] can be expressed as the following [Equation 6].

[0078]

[0079] When the above formula (6) is written for each wavelength of the measurement light L1, it is expressed by the upper and lower formulas of the following formula (7).

[0080]

[0081] Since the left side of the upper equation and the left side of the lower equation of the above [Equation 7] are equal, the following [Equation 8] can be obtained from the above [Equation 7].

[0082]

[0083] By modifying the above [Equation 8], the temperature change ΔT can be derived as shown in the following [Equation 9]. As a result, similar to the first embodiment, the wafer temperature can be calculated based on the derived temperature change ΔT and the known reference temperature T.

[0084]

[0085] The actual thickness L of the wafer W ｖ can be expressed by three different equations as shown in the following [Equation 10]. Therefore, by substituting the temperature change ΔT obtained by the above [Equation 9] into one of the three equations, the actual thickness L of the wafer W can be calculated. ｖ is required.

[0086]

[0087] The flow of the non-contact temperature measuring method for the wafer W by the non-contact temperature measuring device 10 of the second embodiment is basically the same as the flow already explained in FIG. 6, so a detailed explanation will be omitted here.

[0088] As described above, the non-contact temperature measuring device 10 of the second embodiment can measure the thickness L of the wafer W using the measurement light L1 with two wavelengths. ｏｐｔ，λｋ By measuring the wafer temperature based on the measurement result of the wafer temperature and the wafer information 29, the actual thickness L of the wafer W during the semiconductor manufacturing process can be calculated. ｖ Even if the temperature of the wafer changes significantly, the wafer temperature can be measured with high accuracy.

[0089] In the non-contact temperature measuring device 10 of the second embodiment, the wafer temperature is measured using measurement light L1 of two wavelengths, but the wafer temperature may also be measured using measurement light L1 of three or more different wavelengths.

[0090] 9 is a schematic diagram of a non-contact temperature measuring device 10 according to a third embodiment. ｏｐｔ (Thickness L ｏｐｔ，λＫ ) and wafer information 29, but the wafer temperature is calculated based on the wafer information 29 (refractive index n, refractive index temperature coefficient Δn ｔ and the linear thermal expansion coefficient α) may become unknown. Therefore, the non-contact temperature measuring device 10 of the third embodiment measures the wafer temperature without using the wafer information 29.

[0091] 9, the non-contact temperature measuring device 10 of the third embodiment has basically the same configuration as the first embodiment, except that correlation data 29A is stored in the storage unit 28 instead of the wafer information 29, the control device 22 functions as a correlation data acquisition unit 35 instead of the wafer information acquisition unit 34, and the method of calculating the wafer temperature by the temperature calculation unit 36 ​​is different. For this reason, components that are the same in function or configuration as those of the first embodiment are given the same reference numerals, and their description will be omitted.

[0092] The correlation data 29A is the thickness L of the wafer W. ｏｐｔ The data indicates the correlation between the temperature and the wafer temperature, and is stored in advance in the storage unit 28 for each type of wafer W.

[0093] 10 is an explanatory diagram for explaining an example of a method for generating correlation data 29 A. As shown in FIG. 10, when generating correlation data 29 A, a temperature sensor 100 is attached to wafer W, and a data logger 102 is connected to thickness measuring device main body 18 and temperature sensor 100.

[0094] The temperature sensor 100 continuously measures the wafer temperature of the wafer W and outputs the measured value to the data logger 102. The thickness measuring device main body 18 also measures the thickness L of the wafer W. ｏｐｔ Measurement of the thickness Lｏｐｔ The measurement results are continuously output to the data logger 102.

[0095] 11 is a diagram showing an example of recorded data recorded by the data logger 102. As shown in FIG. 11, the data logger 102 records the wafer temperature (see symbol XIA) continuously input from the temperature sensor 100 and the thickness L of the wafer W continuously input from the thickness measuring device main body 18. ｏｐｔ (See symbol XIB) and are recorded on the same time axis. ｏｐｔ The recording is repeatedly performed at temperatures close to the actual operating temperature.

[0096] 12 is a diagram showing an example of the correlation data 29A. As shown in FIG. 12, the wafer temperature and thickness L recorded by the data logger 102 ｏｐｔ By performing linear approximation processing (or polynomial approximation processing depending on the measurement object) on the recorded data, the thickness L of the wafer W can be calculated. ｏｐｔ Correlation data 29A (here, a mathematical formula) showing the correlation between the temperature and the wafer is obtained.

[0097] 12. Alternatively, a data table may be generated as the correlation data 29A. ｏｐｔ The recorded data is used as training data, and the thickness L ｏｐｔ Alternatively, a machine learning model may be generated that uses the above as input and the wafer temperature as output, and this machine learning model may be used as correlation data 29A.

[0098] Returning to FIG. 9, the functions of the measurement control unit 30 and thickness acquisition unit 32 of the third embodiment are the same as those of the measurement control unit 30 and thickness acquisition unit 32 of the first embodiment, and therefore a detailed description thereof will be omitted here.

[0099] The correlation data acquisition unit 35 operates in response to, for example, input of a temperature measurement start operation, acquires the correlation data 29A from the storage unit 28, and outputs the correlation data 29A to the temperature calculation unit 36. Note that instead of acquiring the correlation data 29A from the storage unit 28, the correlation data acquisition unit 35 may acquire the correlation data 29A from an external server via a known communication network.

[0100] The temperature calculation unit 36 ​​of the third embodiment calculates the thickness L ｏｐｔ Based on this, the correlation data 29A input from the correlation data acquisition unit 35 is referenced to calculate the wafer temperature.

[0101] 13 is a flowchart showing the flow of the non-contact temperature measuring method for a wafer W using the non-contact temperature measuring device 10 of the third embodiment. It is assumed that the correlation data 29A is stored in advance in the storage unit 28. The processes from step S1 to step S4 are the same as those in the first embodiment described with reference to FIG. 6, and therefore will not be described here.

[0102] 13 , in response to input of a temperature measurement start operation to operation unit 24, correlation data acquisition unit 35 acquires correlation data 29A from storage unit 28 and outputs this correlation data 29A to temperature calculation unit 36 ​​(step S5A, which corresponds to the correlation data acquisition step of the present invention). Note that the timing of acquisition of correlation data 29A by correlation data acquisition unit 35 is not particularly limited as long as it is before the wafer temperature is calculated by temperature calculation unit 36.

[0103] Next, the temperature calculation unit 36 ​​calculates the thickness L ｏｐｔ Based on this, the temperature calculation unit 36 ​​calculates the wafer temperature by referring to the correlation data 29A input from the correlation data acquisition unit 35 (step S6A, which corresponds to the temperature calculation step of the present invention). ｏｐｔ The wafer temperature can be calculated directly from the

[0104] As described above, in the non-contact temperature measuring device 10 of the third embodiment, the thickness L of the wafer W ｏｐｔ Since the wafer temperature can be measured by simply contactlessly measuring the thickness L ｏｐｔ Since the wafer temperature can be calculated directly from the temperature sensor, the wafer temperature can be calculated more simply and in a shorter time than in the first embodiment.

[0105] [Others] In each of the above embodiments, the thickness L of the wafer W ｏｐｔ(Thickness L ｏｐｔ，λｋ 1 and 7, the thickness measuring devices 12 and 12A are shown as examples of thickness measuring devices that non-contactly measure the thickness L of the wafer W. ｏｐｔ The configuration of the thickness measuring devices 12 and 12A can be changed as appropriate as long as they can be optically measured in a non-contact manner.

[0106] In each of the above embodiments, a non-contact temperature measuring device 10 that measures the temperature of a wafer W in a non-contact manner has been used as an example, but the present invention can also be applied to a non-contact temperature measuring device 10 that measures the temperature of various optically transparent objects in a non-contact manner.

[0107] 10...Non-contact temperature measuring device, 12...Thickness measuring device, 12A...Thickness measuring device, 14...Sensor head, 16...Optical fiber cable, 17...Optical fiber coupler, 18...Thickness measuring device main body, 18-1...Thickness measuring device main body, 18-2...Thickness measuring device main body, 18a...Light source, 18b...Light receiving sensor, 18c...Thickness calculation unit, 20...Computer, 22...Control device, 24...Operation unit, 26...Display unit, 28...Memory unit, 29...Wafer information, 29A...Correlation data, 30...Measurement control unit, 32...Thickness acquisition unit, 34...Wafer information acquisition unit, 35...Correlation data acquisition unit, 36...Temperature calculation unit, 100...Temperature sensor, 102...Data logger, L1...Measurement light, L2...Reflected light, L2A...Reflected light, L2B...Reflected light, L ｏｐｔ ...Thickness, L ｖ ...actual thickness, T...reference temperature, W...wafer, Wa...surface, Wb...back surface, n...refractive index, n λＫ ...Refractive index, ΔT...Temperature change, Δn ｔ …Temperature coefficient of refractive index, α…Linear thermal expansion coefficient

Claims

1. In a non-contact temperature measurement device that measures the temperature of a light-transmissive object to be measured having a front surface and a back surface in a non-contact manner, a light emitting unit that emits measurement light toward the front surface, a light receiving unit that receives the reflected light of the measurement light reflected by the front surface and the reflected light of the measurement light that has passed through the interior of the object to be measured from the front surface and is reflected by the back surface on the side opposite to the front surface of the object to be measured, and outputs a light reception signal, a thickness calculation unit that calculates the second thickness based on the light reception signal output from the light receiving unit when the actual thickness of the object to be measured is defined as the first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is defined as the second thickness, an object information acquisition unit that acquires object information to be measured including the first thickness, the refractive index, and the refractive index temperature coefficient of the object to be measured, and a temperature calculation unit that calculates the temperature of the object to be measured based on the second thickness calculated by the thickness calculation unit and the object information acquired by the object information acquisition unit. A non-contact temperature measurement device comprising:

2. The non-contact temperature measurement device according to claim 1, wherein the object information acquisition unit acquires the object information to be measured including the first thickness, the refractive index, the refractive index temperature coefficient, and the linear thermal expansion coefficient of the object to be measured.

3. The light emitting unit emits the measurement light of a plurality of wavelengths toward the front surface, the light receiving unit receives the reflected light for each wavelength and outputs the light reception signal, the thickness calculation unit calculates the second thickness for each wavelength based on the light reception signal for each wavelength output from the light receiving unit, and the temperature calculation unit calculates the temperature of the object to be measured based on the second thickness for each wavelength calculated by the thickness calculation unit and the object information. The non-contact temperature measurement device according to claim 1 or 2.

4. In a non-contact temperature measurement device that measures the temperature of a light-transmissive object to be measured having a front surface and a back surface in a non-contact manner, a light emitting unit that emits measurement light toward the front surface; a light receiving unit that receives the reflected light of the measurement light reflected from the front surface and the reflected light of the measurement light that has passed through the interior of the object to be measured from the front surface and is reflected from the back surface on the side opposite to the front surface of the object to be measured, and outputs a light receiving signal; a thickness calculation unit that calculates the second thickness based on the light receiving signal output from the light receiving unit when the actual thickness of the object to be measured is defined as the first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is defined as the second thickness; a correlation data acquisition unit that acquires in advance correlation data indicating the correlation between the second thickness and the temperature of the object to be measured; a temperature calculation unit that calculates the temperature of the object to be measured by referring to the correlation data acquired by the correlation data acquisition unit based on the second thickness calculated by the thickness calculation unit. A non-contact temperature measurement device comprising:

5. In a non-contact temperature measurement method for measuring the temperature of a light-transmissive object to be measured having a front surface and a back surface in a non-contact manner, a light emitting step of emitting measurement light toward the front surface; a light receiving step of receiving the reflected light of the measurement light reflected from the front surface and the reflected light of the measurement light that has passed through the interior of the object to be measured from the front surface and is reflected from the back surface on the side opposite to the front surface of the object to be measured, and outputting a light receiving signal; a thickness calculation step of calculating the second thickness based on the light receiving signal output in the light receiving step when the actual thickness of the object to be measured is defined as the first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is defined as the second thickness; an object information acquisition step of acquiring object information including the first thickness, the refractive index, and the refractive index temperature coefficient of the object to be measured; a temperature calculation step of calculating the temperature of the object to be measured based on the second thickness calculated in the thickness calculation step and the object information acquired in the object information acquisition step. A non-contact temperature measurement method comprising:

6. In a non-contact temperature measurement method for non-contact measurement of the temperature of a light-transmissive object having a front surface and a back surface, a light emission step of emitting measurement light toward the front surface, a light reception step of receiving the reflected light of the measurement light reflected by the front surface and the reflected light of the measurement light transmitted through the interior of the object to be measured from the front surface and reflected by the back surface on the side opposite to the front surface of the object to be measured and outputting a light reception signal, a thickness calculation step of calculating the second thickness when the actual thickness of the object to be measured is defined as the first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is defined as the second thickness, based on the light reception signal output in the light reception step, a correlation data acquisition step of previously acquiring correlation data indicating the correlation between the second thickness and the temperature of the object to be measured, and a temperature calculation step of calculating the temperature of the object to be measured with reference to the correlation data acquired in the correlation data acquisition step, based on the second thickness calculated in the thickness calculation step. A non-contact temperature measurement method having these steps.

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