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

Abstract

To provide a non-contact temperature measuring device and a non-contact temperature measuring method that can simply and accurately execute measurement of the temperature of an object to be measured.SOLUTION: A non-contact temperature measuring device comprises: a light emitting unit (light source 18a) that emits measurement light LA toward a front face Wa; a light receiving unit (light receiving sensor 18b) that receives reflected light L2A of measurement light L1 reflected on the front face Wa, and reflected light L2B of the measurement light L1 reflected on a rear face Wb on the opposite side of the front face Wa of an object to be measured, and outputs a light reception signal; a thickness calculation unit 18c that, when the actual thickness of the object to be measured is defined as a first thickness (thickness Lv) and a thickness obtained by multiplying the first thickness by the refractive index of the object to be measured as a second thickness (thickness Lopt), calculates the second thickness on the basis of the light reception signal output from the light receiving unit; an object-to-be-measured information acquisition unit (wafer information acquisition unit 34) that acquires object-to-be-measured information (wafer information 29); and a temperature calculation unit 36 that calculates the temperature of the object to be measured on the basis of the second thickness and the object-to-be-measured information.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a non-contact temperature measurement device and a non-contact temperature measurement method for non-contact measurement of the temperature of a light-transmissive object to be measured.

Background Art

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

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

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, when measuring the temperature of a wafer with an electric thermometer, since it is necessary to bring this electric thermometer into contact with the wafer, there arises a problem that the work of the operator becomes more troublesome. Also, there is a risk that the measurement error of the electric thermometer increases due to electromagnetic interference, high magnetic field, or high voltage effects on the lead wires of the electric thermometer.

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

[0008] The fluorescent optical fiber thermometer is resistant to electrical, magnetic, and mechanical noises, but it is necessary to bring a phosphor into contact with the wafer. For this reason, temperature measurement with a fluorescent optical fiber thermometer is not a completely non-contact measurement, and there arises a problem that the work of the operator becomes more troublesome.

[0009] The present invention has been made in view of such circumstances, and an object thereof is to provide a non-contact temperature measurement device and a non-contact temperature measurement method capable of easily and highly accurately measuring the temperature of an object to be measured.

Means for Solving the Problems

[0010] A non-contact temperature measurement device for achieving the object of the present invention is a non-contact temperature measurement device that non-contact measures the temperature of a light-transmissive object to be measured having a front surface and a back surface. The non-contact temperature measurement device includes a light emitting unit that emits measurement light toward the front surface, a reflected light of the measurement light reflected by the front surface, and a 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 on the side opposite to the front surface of the object to be measured. A light receiving unit that receives the light and outputs a light reception signal, when 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 thickness calculation unit that calculates the second thickness based on the light reception signal output from the light receiving unit, an object information acquisition unit that acquires object 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 object information acquired by the object information acquisition unit.

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

[0012] In the 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, the refractive index, the refractive index temperature coefficient, and the linear thermal expansion coefficient of the object to be measured. Thereby, the temperature of the object to be measured can be non-contact measured based on the measurement result of non-contact measuring the second thickness of the object to be measured.

[0013] In the non-contact temperature measurement device according to another aspect of the present invention, the light emitting unit emits measurement light of a plurality of wavelengths toward the front surface, and the light receiving unit receives the reflected light for each wavelength and outputs a 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.

[0014] A non-contact temperature measurement device for achieving the object of the present invention is a non-contact temperature measurement device that non-contact measures the temperature of a light-transmissive object to be measured having a front surface and a back surface. The non-contact temperature measurement device includes a light emitting unit that emits measurement light toward the front surface, a reflected light of the measurement light reflected by the front surface, and a 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 on the opposite side of the object to be measured from the front surface. A light receiving unit that receives the reflected light 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 when 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 in advance correlation data indicating 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 measurement device, the temperature of the object to be measured can be non-contact measured based on the measurement result of non-contact measuring the second thickness of the object to be measured.

[0016] A non-contact temperature measurement method for achieving the object of the present invention is a non-contact temperature measurement method that non-contact measures the temperature of a light-transmissive object to be measured having a front surface and a back surface. The non-contact temperature measurement method includes a light emitting step of emitting measurement light toward the front surface, a light receiving step of receiving a reflected light of the measurement light reflected by the front surface and a 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 on the opposite side of the object to be measured from the front surface 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 when 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, 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, and 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.

[0017] A non-contact temperature measurement method for achieving the object of the present invention is a non-contact temperature measurement method for non-contact measurement of the temperature of a light-transmissive object to be measured having a front surface and a back surface. The method includes 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 from the front surface and the reflected light of the measurement light transmitted through the inside of the object to be measured from the front surface and reflected from 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 a second thickness by multiplying the actual thickness of the object to be measured by the refractive index of the object to be measured when the actual thickness of the object to be measured is defined as a first thickness, 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.

Advantages of the Invention

[0018] The present invention can easily and highly accurately measure the temperature of an object to be measured.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

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Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

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

[0021] The non-contact temperature measurement device 10 includes a thickness measuring device 12 and a computer 20. Note that the functions of the computer 20 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 also functions as a non-contact temperature measurement device 10 alone.

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

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

[0024] FIG. 2 is an explanatory diagram for explaining 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 aforementioned FIG. 1, the sensor head 14 corresponds to the light emitting part of the present invention and is disposed at a position facing the surface Wa of the wafer W. Here, the surface Wa is a facing surface facing the sensor head 14 and is an incident surface on which the measurement light L1 from the sensor head 14 is incident. Also, the back surface Wb of the wafer W is a surface on the opposite side of the surface Wa of the wafer W.

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

[0026] A part of the measurement light L1 incident on the surface Wa from the sensor head 14 is reflected from the surface Wa as the reflected light L2A and directed toward the sensor head 14, and the rest passes through the inside of the wafer W and reaches the back surface Wb of the wafer W. For example, if the wafer W is a silicon wafer [refractive index is 3.483 (wavelength of the measurement light L1: 1.5 μm), temperature coefficient is 1.8×10 -4When it is the case, 27% of the measurement light L1 becomes the reflected light L2A.

[0027] A part of the measurement light L1 that has reached the back surface Wb is reflected from the back surface Wb toward the front surface Wa as the reflected light L2B, and the rest is emitted from the back surface Wb to the outside of the wafer W. Then, a 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 rest is reflected again from the front surface Wa toward the back surface Wb.

[0028] When the wafer W is the above-mentioned silicon wafer, 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] The reflected light L2 including the reflected light L2A reflected on the front surface Wa and the reflected light L2B reflected on the back surface Wb enters the sensor head 14. The reflected light L2 that has entered the sensor head 14 enters 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, a thickness calculation unit 18c, and the like.

[0031] The light source 18a emits the measurement light L1 to the optical fiber cable 16. Thereby, the measurement light L1 enters the sensor head 14 via the optical fiber cable 16, and the measurement light L1 is emitted from this sensor head 14 toward the front surface Wa. The light receiving sensor 18b corresponds to the light receiving unit of the present invention, and receives the reflected light L2 incident from the sensor head 14 via the optical fiber cable 16 and outputs a light receiving signal. Note that 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 opt (corresponding to the second thickness of the present invention) of the wafer W based on the light receiving signal output from the light receiving sensor 18b, and this thickness L optOutput the calculation result to the computer 20. Note that for the thickness L in a wavelength-scanning laser interferometer, an interferometer using the spectroscopic interference method, and an interferometer using the vertical scanning low coherence interference method opt Since the calculation method of opt is a known technique, specific description is omitted here. Also, the thickness L of the wafer W calculated by the thickness calculation unit 18c opt is the thickness obtained by multiplying the refractive index of the wafer W by the actual thickness L v (corresponding to the first thickness of the present invention), so it is different from the actual thickness L v is different.

[0033] Note that the thickness calculation unit 18c may be provided in the control device 22 (see FIG. 3) of the computer 20 described later. In this case, the light receiving sensor 18b outputs the 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 various known arithmetic units may be used instead of the computer 20.

[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 calculation of the thickness L opt ), and calculates the wafer temperature. The thickness measuring device main body 18, the operation unit 24, and the display unit 26 are connected to this control device 22.

[0036] The operation unit 24 receives various operations of the non-contact temperature measuring device 10, for example, 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 uses, for example, a liquid crystal display, and displays various setting screens of the non-contact temperature measuring device 10 and the measurement results of the wafer temperature, etc.

[0038] FIG. 3 is a functional block diagram of the control device 22 of the first embodiment. As shown in FIG. 3, the control device 22 includes an arithmetic circuit composed of various processors and a memory. The various processors include a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), and programmable logic devices [e.g., SPLD (Simple Programmable Logic Devices), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Arrays)]. Note that the various functions of the control device 22 may be realized by one processor or by a plurality of processors of the same type or different types.

[0039] Connected to the control device 22 in addition to the above-described thickness measuring device main body 18, operation unit 24, and display unit 26 is a storage unit 28. Note that the storage unit 28 may be built in the control device 22. Stored in this storage unit 28 in advance for each type of wafer W is wafer information 29 corresponding to the information on the object to be measured of the present invention, in addition to a control program (not shown) of the control device 22.

[0040] The wafer information 29 is information regarding the actual dimensions, properties, and characteristics of the material (such as silicon) 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 different from the method using the thickness measuring device 12 v and the known refractive index n of the wafer W, the refractive index temperature coefficient Δn t and the linear thermal expansion coefficient α.

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

[0042] The measurement control unit 30 operates in response to the input of a temperature measurement start operation 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 causes the measurement light L1 to be emitted from the light source 18a, the reflected light L2 to be received by the light receiving sensor 18b and the output of the light receiving signal, and the thickness L opt to be calculated by the thickness calculation unit 18c.

[0043] The thickness acquisition unit 32 corresponds to the measured object information acquisition unit of the present invention. When the thickness calculation unit 18c executes the calculation of the thickness L opt the thickness acquisition unit 32 acquires the calculation result of the thickness L opt from the thickness calculation unit 18c and outputs this calculation result to the temperature calculation unit 36.

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

[0045] The temperature calculation unit 36 calculates the wafer temperature based on the thickness L opt input from the thickness acquisition unit 32 and the wafer information 29 input from the wafer information acquisition unit 34. Hereinafter, an example of the calculation of the wafer temperature by the temperature calculation unit 36 will be specifically described.

[0046] As described above, the thickness L opt of the wafer W is the thickness obtained by multiplying the actual thickness L v by the refractive index n of the wafer W. Therefore, the actual thickness L v is represented by the following equation [Equation 1].

[0047]

Equation

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

[0049]

Equation

[0050] In the above [Equation 2], the refractive index n and the refractive index temperature coefficient Δn t at the reference temperature T are known values because they are parameters related to the material of the wafer W. Also, the linear thermal expansion coefficient α is a known value because it is a parameter related to the material of the wafer W. Therefore, by previously obtaining the above-described wafer information 29 (actual thickness L v , refractive index n, refractive index temperature coefficient Δn t and linear thermal expansion coefficient α), based on the thickness L opt and the wafer information 29, the temperature change ΔT can be derived as shown in the following [Equation 3]. And based on the derived temperature change ΔT and the known reference temperature T, the wafer temperature can be calculated.

[0051]

Equation

[0052] The temperature calculation unit 36 calculates the temperature change ΔT using the above [Equation 3] based on the thickness L opt input from the thickness acquisition unit 32 and the wafer information 29 input from the wafer information acquisition unit 34, and calculates the wafer temperature based on this temperature change ΔT and the known reference temperature T.

[0053] Note that in the above [Equation 3], the refractive index temperature coefficient Δn tis about 100 times the linear thermal expansion coefficient α. Therefore, depending on the required accuracy 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]

Equation

[0055] FIG. 4 is a graph showing the relationship between the thickness L and the temperature change ΔT when 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). Note that the graph of reference numeral 4A in FIG. 4 shows the relationship between the thickness L opt and the temperature change ΔT when the linear thermal expansion coefficient α is set to "α = 2.6×10 -6 ". Also, the graph of reference numeral 4B in FIG. 4 shows the relationship between the thickness L opt and the temperature change ΔT when the linear thermal expansion coefficient α is simplified to "α = 0.0". opt

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

[0057] As shown in FIGS. 4 and 5, since the error between the case where the linear thermal expansion coefficient α is simplified to "α = 0.0" and the case where it is not simplified is small, it is confirmed that there is no problem in simplifying the linear thermal expansion coefficient α depending on the required accuracy of the wafer temperature. In this case, since the calculation of the temperature change ΔT by the temperature calculation unit 36 is simplified, the time required for calculating the wafer temperature is shortened.

[0058] [Operation of the Non-Contact Temperature Measurement Device of the First Embodiment] FIG. 6 is a flowchart showing the flow of the non-contact temperature measurement method of the wafer W by the non-contact temperature measurement device 10 of the first embodiment. Note that it is assumed that the wafer information 29 is stored in the storage unit 28 in advance. ​

[0059] 6, when a temperature measurement start operation is input to operation unit 24 (step S1), control device 22 functions as measurement control unit 30, thickness acquisition unit 32, wafer information acquisition unit 34, and temperature calculation unit 36. Then, measurement control unit 30 causes thickness measurement of wafer W to be performed by thickness measuring device 12. As a result, measurement light L1 is emitted from light source 18a, and measurement light L1 is emitted from sensor head 14 toward surface Wa of wafer W via optical fiber cable 16 (step S2, corresponding 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 step of acquiring information about the object to be measured 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 calculation of the wafer temperature by temperature calculation unit 36.

[0063] Then, the temperature calculation unit 36 calculates the thickness L optBased 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 wafer temperature only by non-contact measurement of the thickness L of the wafer W opt Therefore, it is possible to measure the wafer temperature non-contact without being affected by electrical, magnetic, and mechanical noises, or by plasma that generates infrared rays. As a result, the temperature measurement of the wafer W can be performed easily and with high accuracy.

[0065] [Second Embodiment] FIG. 7 is a schematic diagram of the non-contact temperature measuring device 10 of the second embodiment. FIG. 8 is a functional block diagram of the control device 22 of the second embodiment. The non-contact temperature measuring device 10 of the first embodiment measures the wafer temperature using the measurement light L1 of a single wavelength. However, during the semiconductor manufacturing process, the actual thickness L of the wafer W v If it changes greatly, there is a possibility that an error will occur in the measurement result of the wafer temperature. Therefore, the non-contact temperature measuring device 10 of the second embodiment measures the wafer temperature non-contact using measurement lights L1 of a plurality of wavelengths (here, two wavelengths).

[0066] As shown in FIGS. 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 different from the thickness measuring device 12 of the first embodiment. Therefore, those having the same functions or configurations as those in the first embodiment are denoted by the same reference numerals, and their descriptions are omitted.

[0067] The thickness measuring device 12A uses measurement lights L1 of two different wavelengths (wavelength λ1, wavelength λ2) to measure the thickness L of the wafer W opt,λ1 and the thickness L opt,λ2It measures without contact. This thickness measuring device 12A includes, in addition to the aforementioned sensor head 14 and the optical fiber cable 16, 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. One end of this optical fiber coupler 17 is connected to the optical fiber cable 16 (sensor head 14), and the other ends are respectively connected to the thickness measuring device main bodies 18-1 and 18-2. The optical fiber coupler 17 combines (multiplexes) the measurement light L1 with wavelength λ1 incident from the thickness measuring device main body 18-1 described later and the measurement light L1 with wavelength λ2 incident from the thickness measuring device main body 18-2 described later and emits them to the optical fiber cable 16 (sensor head 14). Also, the optical fiber coupler 17 divides the reflected light L2 of two wavelengths incident from the optical fiber cable 16, emits the reflected light L2 with wavelength λ1 to the thickness measuring device main body 18-1, and emits the reflected light L2 with wavelength λ2 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 the measurement light L1 with wavelength λ1, and the light source 18a of the thickness measuring device main body 18-2 emits the measurement light L1 with wavelength λ2 different from wavelength λ1. These measurement lights L1 with wavelength λ1 and measurement lights L1 with wavelength λ2 are combined by the optical fiber coupler 17 and then enter the sensor head 14 through the optical fiber cable 16 and are emitted from this sensor head 14 toward the surface Wa. As a result, the reflected light L2 of two wavelengths (wavelength λ1, wavelength λ2) enters the optical fiber coupler 17 from the sensor head 14 through the optical fiber cable 16 and is divided into the reflected light L2 with wavelength λ1 and the reflected light L2 with wavelength λ2. Then, the reflected light L2 with wavelength λ1 is emitted from the optical fiber coupler 17 to the thickness measuring device main body 18-1, and the reflected light L2 with wavelength λ2 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 reflected light L2 with a wavelength λ1 incident from the optical fiber coupler 17 and outputs a light receiving signal, and the thickness calculation unit 18c of the thickness measuring device main body 18-1 calculates the thickness L of the wafer W based on this light receiving signal. opt,λ1 Also, the light receiving sensor 18b of the thickness measuring device main body 18-2 receives the reflected light L2 with a wavelength λ2 incident from the optical fiber coupler 17 and outputs a light receiving signal, and the thickness calculation unit 18c of the thickness measuring device main body 18-2 calculates the thickness L of the wafer W based on this light receiving signal. opt,λ2 to calculate.

[0072] In response to the input of the temperature measurement start operation to the operation unit 24, the measurement control unit 30 of the second embodiment causes each of the thickness measuring device main bodies 18-1 and 18-2 to emit the measurement light L1 from the light source 18a, receive the reflected light L2 by the light receiving sensor 18b and output the light receiving signal, and calculate the thickness L opt,λk [K = 1, 2]. As a result, the thickness L opt,λk is measured non-contact for each wavelength of the measurement light L1.

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

[0074] The temperature calculation unit 36 of the second embodiment calculates the temperature change ΔT in the same manner as in the first embodiment based on the thickness L opt,λk and the wafer information 29 for each wavelength of the measurement light L1. 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. Hereinafter, an example of the calculation of the wafer temperature by the temperature calculation unit 36 of the second embodiment will be specifically described.

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

[0076] [Equation]

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

[0078] [Equation]

[0079] When the above [Equation 6] is written down for each wavelength of the measurement light L1, it is represented by the upper equation and the lower equation of the following [Equation 7].

[0080] [Equation]

[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] [Equation]

[0083] And, when the above [Equation 8] is transformed, the temperature change ΔT can be derived as shown in the following [Equation 9]. Thus, similarly to the above first embodiment, the wafer temperature can be calculated based on the derived temperature change ΔT and the known reference temperature T.

[0084] [Equation]

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

[0086] [Equation]

[0087] Regarding the flow of the non-contact temperature measurement method of the wafer W by the non-contact temperature measurement device 10 of the second embodiment, since it is basically the same as the flow described in FIG. 6 mentioned above, specific description is omitted here.

[0088] As described above, the non-contact temperature measurement device 10 of the second embodiment measures the wafer temperature based on the measurement result of the thickness L of the wafer W using the measurement light L1 of two wavelengths opt,λk and the wafer information 29, so that even when the actual thickness L of the wafer W v changes greatly during the semiconductor manufacturing process, the wafer temperature can be measured accurately.

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

[0090] [Third Embodiment] FIG. 9 is a schematic diagram of the non-contact temperature measurement device 10 of the third embodiment. The non-contact temperature measurement device 10 of each of the above embodiments calculates the wafer temperature based on the thickness L of the wafer W opt (thickness L opt,λK ) and the wafer information 29. However, due to the doping process on the wafer W, the wafer information 29 (refractive index n, refractive index temperature coefficient Δn tand the linear thermal expansion coefficient α) may become unclear. Therefore, the non-contact temperature measuring device 10 of the third embodiment measures the wafer temperature without using the wafer information 29.

[0091] As shown in FIG. 9, the non-contact temperature measuring device 10 of the third embodiment is basically the same 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 calculation method of the wafer temperature by the temperature calculation unit 36 is different. For this reason, those that are the same as those in the first embodiment in terms of function or configuration are denoted by the same reference numerals and their description is omitted.

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

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

[0094] The temperature sensor 100 continuously measures the wafer temperature of the wafer W and continuously outputs it to the data logger 102. In addition, the thickness measuring device main body 18 continuously measures the thickness L of the wafer W opt and continuously outputs the measurement result of this thickness L opt to the data logger 102.

[0095] FIG. 11 is a diagram showing an example of the recording data recorded by the data logger 102. As shown in FIG. 11, the data logger 102 includes the wafer temperature (see reference symbol XIA) continuously input from the temperature sensor 100 and the thickness L of the wafer W opt (see reference symbol XIB) continuously input from the thickness measuring device main body 18 are recorded on the same time axis. Note that the wafer temperature and the thickness L by the data logger 102opt The recording is repeatedly executed near the temperature at which it is actually operated.

[0096] FIG. 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 (polynomial approximation processing depending on the measurement target) on the recorded data of, the thickness L of the wafer W opt The correlation data 29A (here, a mathematical formula) showing the correlation between the wafer temperature and the wafer temperature is obtained.

[0097] Note that a data table may be generated instead of the mathematical formula shown in FIG. 12 as the correlation data 29A. Alternatively, the wafer temperature and thickness L recorded by the data logger 102 opt Using the recorded data as teacher data, a machine learning model that outputs the wafer temperature with the thickness L opt As an input may be generated, and this machine learning model may be used as the correlation data 29A.

[0098] Returning to FIG. 9, since the functions of the measurement control unit 30 and the thickness acquisition unit 32 of the third embodiment are the same as those of the measurement control unit 30 and the thickness acquisition unit 32 of the first embodiment, specific description thereof is omitted here.

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

[0100] The temperature calculation unit 36 of the third embodiment calculates the wafer temperature with reference to the correlation data 29A input from the correlation data acquisition unit 35 based on the thickness L opt input from the thickness acquisition unit 32.

[0101] FIG. 13 is a flowchart showing the flow of the non-contact temperature measurement method of the wafer W by the non-contact temperature measurement device 10 of the third embodiment. It is assumed that the correlation data 29A is stored in the storage unit 28 in advance. In addition, since the processes from step S1 to step S4 are the same as those of the first embodiment described with reference to FIG. 6 above, the description thereof is omitted here.

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

[0103] Next, based on the thickness L input from the thickness calculation unit 18c, the temperature calculation unit 36 refers to the correlation data 29A input from the correlation data acquisition unit 35 and calculates the wafer temperature (step S6A, corresponding to the temperature calculation step of the present invention). By using the correlation data 29A, the temperature calculation unit 36 can directly calculate the wafer temperature from the thickness L. opt opt

[0104] As described above, also in the non-contact temperature measurement device 10 of the third embodiment, the wafer temperature can be measured only by non-contact measurement of the thickness L of the wafer W, so the same effect as that of the non-contact temperature measurement device 10 of the first embodiment described above can be obtained. Further, in the third embodiment, since the wafer temperature can be directly calculated from the thickness L, the wafer temperature can be calculated more simply and in a shorter time than in the first embodiment. opt opt

[0105] [Others] In each of the above embodiments, the thickness measuring devices 12 and 12A (see FIGS. 1 and 7) are exemplified as the thickness measuring devices that non-contact measure the thickness L of the wafer W (including the thickness L). opt (Including the thickness L opt,λk ), but the thickness L of the wafer Wopt If it is optically non-contact measurable, the configuration of the thickness gauges 12 and 12A can be changed as appropriate.

[0106] In each of the above embodiments, the non-contact temperature measurement device 10 for non-contact measurement of the temperature of the wafer W has been described as an example, but the present invention is also applicable to a non-contact temperature measurement device 10 for non-contact measurement of the temperature of various objects to be measured having optical transparency.

Explanation of Reference Numerals

[0107] 10…Non-contact temperature measurement device, 12…Thickness gauge, 12A…Thickness gauge, 14…Sensor head, 16…Optical fiber cable, 17…Optical fiber coupler, 18…Thickness gauge main body, 18-1…Thickness gauge main body, 18-2…Thickness gauge 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…Storage 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 …Refractive index temperature coefficient, α…Linear thermal expansion coefficient

Claims

1. A non-contact temperature measuring device for measuring the temperature of a light-transmitting object having a front surface and a back surface, a light emitting unit that emits measurement light toward the surface; a light receiving unit that receives the reflected light of the measurement light reflected by the surface and the reflected light of the measurement light that has passed through the interior of the object from the surface and is reflected by a rear surface opposite to the surface of the object, 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, where the actual thickness of the object to be measured is a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is a second thickness; an object information acquiring unit that acquires object information including the first thickness, the refractive index, and a refractive index temperature coefficient of the object; a temperature calculation unit that calculates a 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 measuring device comprising:

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

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

4. A non-contact temperature measuring device for measuring the temperature of a light-transmitting object having a front surface and a back surface, a light emitting unit that emits measurement light toward the surface; a light receiving unit that receives the reflected light of the measurement light reflected by the surface and the reflected light of the measurement light that has passed through the interior of the object from the surface and is reflected by a rear surface opposite to the surface of the object, 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, where the actual thickness of the object to be measured is a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is a second thickness; a correlation data acquiring unit that acquires correlation data indicating a correlation between the second thickness and the temperature of the object to be measured in advance; a temperature calculation unit that calculates a temperature of the object to be measured based on the second thickness calculated by the thickness calculation unit and with reference to the correlation data acquired by the correlation data acquisition unit; A non-contact temperature measuring device comprising:

5. A non-contact temperature measurement method for measuring the temperature of a light-transmitting object having a front surface and a back surface, comprising: a light emitting step of emitting measurement light toward the surface; a light receiving step of receiving reflected light of the measurement light reflected by the surface and reflected light of the measurement light transmitted through the interior of the object from the surface and reflected by a rear surface opposite to the surface of the object, 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, where the actual thickness of the object to be measured is a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is a second thickness; an object information acquiring step of acquiring object information including the first thickness, the refractive index, and a refractive index temperature coefficient of the object; a temperature calculation step of calculating a 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. A non-contact temperature measurement method for measuring the temperature of a light-transmitting object having a front surface and a back surface, comprising: a light emitting step of emitting measurement light toward the surface; a light receiving step of receiving reflected light of the measurement light reflected by the surface and reflected light of the measurement light transmitted through the interior of the object from the surface and reflected by a rear surface opposite to the surface of the object, 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, where the actual thickness of the object to be measured is a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is a second thickness; a correlation data acquiring step of acquiring correlation data indicating a correlation between the second thickness and the temperature of the object; a temperature calculation step of calculating a temperature of the object based on the second thickness calculated in the thickness calculation step and with reference to the correlation data acquired in the correlation data acquisition step; A non-contact temperature measurement method comprising:

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