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

Abstract

A light emitting unit (light source (18a)) that emits a measurement light (L1) toward a surface (Wa), a light receiving unit (light receiving sensor (18b)) that receives a light receiving signal by receiving a reflected light (L2A) of the measurement light (L1) reflected from the surface (Wa) and a reflected light (L2B) of the measurement light (L1) reflected from a back surface (Wb) opposite to the surface (Wa) of the object to be measured, and a thickness calculation unit (18c) that calculates a second thickness based on a light receiving signal output from the light receiving unit when the actual thickness of the object to be measured is set as a first thickness (thickness Lv) and the thickness obtained by multiplying the first thickness by the refractive index of the object to be measured is set as a second thickness (thickness (Lopt)), a object information acquisition unit (wafer information acquisition unit (34)) that acquires object information (wafer information (29)), and a temperature calculation unit (36) that calculates the temperature of the object to be measured based on the second thickness and object information. Provides.

Description

Technology Field

[0001] The present invention relates to a non-contact temperature measuring device and a non-contact temperature measuring method for measuring the temperature of a light-transmitting object without contact. Background Technology

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

[0003] Methods for measuring the temperature of a wafer (object to be measured) include, for example, using electric thermometers (thermocouples, thermistors, platinum resistance thermometers, etc.), using radiation thermometers, and using fluorescent optical fiber thermometers. Prior art literature

[0004] Japanese Patent Publication No. 2018-073962 and Japanese Patent Publication No. 2020-077864

[0005] Kenji Ishikawa et al., "The Cutting Edge of Ultra-Dry Etching Technology Realizing Advanced Device Structures", [online], J. Plasma Fusion Res. Vol.97, No.9 (2021) 508-510, [Accessed 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], Measurement and Control Vol. 47, No. 5, May 2008, [Accessed December 27, 2023], Internet<URL: https: / / www.jstage.jst.go.jp / article / sicejl / 47 / 5 / 47_395 / _pdf> The problem to be solved

[0006] However, when measuring the wafer temperature using an electric thermometer, the problem arises that the operator's workload increases because the thermometer must be brought into contact with the wafer. Furthermore, there is a risk that the measurement error of the electric thermometer may increase due to electromagnetic interference on the thermometer's lead wires, or the influence of high magnetic fields or high voltage.

[0007] When measuring the temperature of a wafer using a radiation thermometer, there is a problem that errors occur in the temperature measurement results if a source generating infrared radiation, such as plasma, is present around the wafer.

[0008] Fluorescent fiber thermometers are resistant to electrical, magnetic, and mechanical noise, but they require contact of a phosphor with the wafer. For this reason, temperature measurement using fluorescent fiber thermometers cannot be considered completely non-contact, leading to the problem of increased workload for the operator.

[0009] The present invention has been made in consideration of these circumstances and aims to provide a non-contact temperature measuring device and a non-contact temperature measuring method capable of measuring the temperature of an object simply and with high precision. means of solving the problem

[0010] A non-contact temperature measuring device for achieving the objective of the present invention comprises a non-contact temperature measuring device for measuring a light-transmitting object having a surface and a back surface, wherein the device comprises: a light emitting unit that emits a measurement light toward a surface; a light receiving unit that receives a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object from the surface and is reflected from the back surface opposite to the surface of the object, and outputs a light receiving signal; a thickness calculation unit that calculates a second thickness based on a light receiving signal output from the light receiving unit when the actual thickness of the object is set as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is set as a second thickness; an object information acquisition unit that acquires object information including a first thickness, a refractive index, and a refractive index temperature coefficient of the object; and a temperature calculation unit that calculates the temperature of the object 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 measuring device, the temperature of a workpiece can be measured non-contactually based on the measurement result of non-contactually measuring the second thickness of the workpiece.

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

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

[0014] The thickness calculation unit calculates a second thickness for each wavelength based on a light reception signal for each wavelength output from the light reception 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 to be measured information.

[0015] A non-contact temperature measuring device for achieving the objective of the present invention comprises a non-contact temperature measuring device for measuring a light-transmitting object having a surface and a back surface, wherein the device comprises: a light-emitting unit that emits a measurement light toward a surface; a light-receiving unit that receives a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object from the surface and is reflected from the back surface opposite to the surface of the object, and outputs a light-receiving signal; a thickness calculation unit that calculates a second thickness based on a light-receiving signal output from the light-receiving unit when the actual thickness of the object is set as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is set as a second thickness; a correlation data acquisition unit that acquires correlation data in advance that indicates the correlation between the second thickness and the temperature of the object; and a temperature calculation unit that calculates the temperature of the object by referring to the correlation data acquired by the correlation data acquisition unit based on the second thickness calculated by the thickness calculation unit.

[0016] According to this non-contact temperature measuring device, the temperature of a workpiece can be measured non-contactually based on the measurement result of non-contactually measuring the second thickness of the workpiece.

[0017] A non-contact temperature measurement method for achieving the objective of the present invention comprises a non-contact temperature measurement method for measuring the temperature of a light-transmitting object having a surface and a back surface, the method comprising: a light emission step for emitting a measurement light toward a surface; a light reception step for receiving a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object from the surface and is reflected from the back surface opposite to the surface of the object, and outputting a light reception signal; a thickness calculation step for calculating a second thickness based on the light reception signal output in the light reception step, wherein the actual thickness of the object is a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is a second thickness; a object information acquisition step for acquiring object information including a first thickness, a refractive index, and a refractive index temperature coefficient of the object; and a temperature calculation step for calculating the temperature of the object based on the second thickness calculated in the thickness calculation step and the object information acquired in the object information acquisition step.

[0018] A non-contact temperature measurement method for achieving the objective of the present invention comprises a non-contact temperature measurement method for measuring the temperature of a light-transmitting object having a surface and a back surface, the method comprising: a light emission step for emitting a measurement light toward a surface; a light reception step for receiving a light signal by receiving a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object from the surface and is reflected from the back surface opposite to the surface of the object; a thickness calculation step for calculating a second thickness based on the light signal output in the light reception step, wherein the actual thickness of the object is a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is a second thickness; a correlation data acquisition step for acquiring correlation data in advance that indicates the correlation between the second thickness and the temperature of the object; and a temperature calculation step for calculating the temperature of the object by referring to the correlation data acquired in the correlation data acquisition step based on the second thickness calculated in the thickness calculation step. Effects of the invention

[0019] The present invention enables simple yet high-precision temperature measurement of an object. Brief explanation of the drawing

[0020] FIG. 1 is a schematic diagram of a non-contact temperature measuring device of a first embodiment. Figure 2 is an explanatory diagram for explaining the measurement light emitted from the sensor head and the reflected light incident on the sensor head. FIG. 3 is a functional block diagram of a control device of the first embodiment. Figure 4 shows the thickness L when the wafer is silicon. opt This is a graph showing the relationship between and the temperature change ΔT. Figure 5 is a graph showing the error between the graph of symbol 4A in Figure 4 and the graph of symbol 4B in Figure 4. FIG. 6 is a flowchart showing the flow of a method for measuring the non-contact temperature of a wafer using a non-contact temperature measuring device of the first embodiment. FIG. 7 is a schematic diagram of a non-contact temperature measuring device of a second embodiment. FIG. 8 is a functional block diagram of a control device of a second embodiment. FIG. 9 is a schematic diagram of a non-contact temperature measuring device of a third embodiment. Figure 10 is an explanatory diagram illustrating an example of a method for generating correlation data. Figure 11 is a diagram showing an example of recorded data recorded by a data logger. Figure 12 is a diagram showing an example of correlation data. FIG. 13 is a flowchart showing the flow of a method for measuring the non-contact temperature of a wafer by a non-contact temperature measuring device of the third embodiment. Specific details for implementing the invention

[0021] [First embodiment]

[0022] FIG. 1 is a schematic diagram of a non-contact temperature measuring device (10) according to a first embodiment of the present invention. The non-contact temperature measuring device (10) is used in a semiconductor manufacturing process for manufacturing various wafers (W), such as silicon, and measures the wafer temperature, which is the temperature of the wafer (W), non-contactually. The wafer (W) corresponds to the object to be measured according to the present invention and has light transmittance. For example, if the wafer (W) is a silicon wafer, the wafer (W) is almost transparent to light with a wavelength of 1.2 μm to 6 μm.

[0023] The non-contact temperature measuring device (10) is equipped with a thickness measuring device (12) and a computer (20). Additionally, the function of the computer (20) described later may be provided in the thickness measuring device (12) (thickness measuring device body (18)). In this case, the thickness measuring device (12) also functions as a single unit of the non-contact temperature measuring device (10).

[0024] The thickness measuring device (12) optically and non-contactually measures the thickness of the wafer (W). Examples of this thickness measuring device (12) include a wavelength-sweeping laser interferometer, an interferometer using spectroscopic interferometry (SS-OCT: Swept Source Optical Coherence Tomography), or an interferometer using vertical scanning low-coherence interferometry [CSI: Coherence Scanning Interferometry, TD(Time-domain)-OCT].

[0025] The thickness measuring device (12) is composed of, for example, a sensor head (14), an optical fiber cable (16), and a thickness measuring device body (18). Additionally, the configuration of the thickness measuring device (12) can be appropriately changed if it is capable of optically non-contact measuring the thickness of a wafer (W).

[0026] 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 FIG. 1 described above, the sensor head (14) corresponds to the light emission unit of the present invention and is positioned opposite to the surface (Wa) of the wafer (W). Here, the surface (Wa) is the opposite surface facing the sensor head (14) and is the incident surface where the measurement light (L1) from the sensor head (14) is incident. In addition, the back surface (Wb) of the wafer (W) is the surface opposite to the surface (Wa) of the wafer (W).

[0027] The sensor head (14) is optically connected to the thickness measuring body (18) via an optical fiber cable (16) and emits measurement light (L1) incident from the thickness measuring body (18) toward the surface (Wa). Additionally, the measurement light (L1) is light of a wavelength (wavelength band) that passes through the wafer (W).

[0028] Measurement light (L1) incident from the sensor head (14) onto the surface (Wa) has a portion reflected from the surface (Wa) toward the sensor head (14) as reflected light (L2A), while the remainder passes through the interior of the wafer (W) and reaches the back side (Wb) of the wafer (W). For example, the wafer (W) is a silicon wafer [refractive index 3.483 (wavelength of measurement light (L1): 1.5 μm), temperature coefficient 1.8 × 10⁻⁶ -4 In the case of ], 27% of the measured light (L1) becomes reflected light (L2A).

[0029] The measurement light (L1) that reaches the back surface (Wb) is partially reflected from the back surface (Wb) toward the surface (Wa) as reflected light (L2B), and the remainder is emitted from the back surface (Wb) to the outside of the wafer (W). Then, the reflected light (L2B) reflected toward the surface (Wa) is partially emitted from the surface (Wa) toward the sensor head (14), and the remainder is reflected again from the surface (Wa) toward the back surface (Wb).

[0030] In addition, if 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 surface (Wa) toward the sensor head (14) is 14% of the original measurement light (L1).

[0031] Reflected light (L2), including reflected light (L2A) reflected from a surface (Wa) and reflected light (L2B) reflected from a 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 body (18) through the optical fiber cable (16).

[0032] Returning to FIG. 1, the thickness measuring device body (18) is equipped with a light source (18a), a light receiving sensor (18b), and a thickness calculation unit (18c), etc.

[0033] The light source (18a) emits measurement light (L1) through the optical fiber cable (16). Accordingly, measurement light (L1) is incident on the sensor head (14) through the optical fiber cable (16), and measurement light (L1) is emitted from the sensor head (14) toward the surface (Wa). Additionally, the light receiving sensor (18b) corresponds to the light receiving part of the present invention and receives reflected light (L2) incident from the sensor head (14) through the optical fiber cable (16) and outputs a light receiving signal. Furthermore, the light source (18a) and the light receiving sensor (18b) may be installed on the sensor head (14).

[0034] The thickness calculation unit (18c) calculates the thickness L of the wafer (W) based on the light signal output from the light receiving sensor (18b). opt Calculate (equivalent to the second thickness of the present invention), and this thickness L opt The calculation result is output to the computer (20). In addition, the thickness L in the wavelength-sweeping laser interferometer, the interferometer using spectroscopic interferometer, and the interferometer using vertical scanning low-coherence interferometer. optAs the calculation method is a known technology, a specific explanation is omitted here. In addition, the thickness L of the wafer (W) calculated by the thickness calculation unit (18c) opt is the actual thickness L of the wafer (W). v Since the thickness is obtained by multiplying the refractive index of the wafer (W) by (equivalent to the first thickness of the present invention), the actual thickness L v It is different from the department.

[0035] Additionally, the thickness calculation unit (18c) may be installed in the control device (22) of the computer (20) described later (see FIG. 3). In this case, the light receiving sensor (18b) outputs the light receiving signal of the reflected light (L2) to the control device (22).

[0036] The computer (20) is equipped with a control unit (22), an operating unit (24), and a display unit (26). Additionally, various known computing devices may be used instead of the computer (20).

[0037] The control device (22) measures the thickness of the wafer (W) by the thickness measuring device (12) (emission of measurement light (L1), reception of reflected light (L2) and thickness L opt It performs control of the operation of the wafer temperature and the operation of the wafer temperature. The control device (22) is connected to the thickness measuring device body (18), the operation unit (24), and the display unit (26).

[0038] The control unit (24) receives various operations of the non-contact temperature measuring device (10), for example, an operation to start measuring the temperature of a wafer (W). The control unit (24) includes various operation devices such as a mouse, a keyboard, and operation buttons.

[0039] 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.

[0040] FIG. 3 is a functional block diagram of a control device (22) of a first embodiment. As shown in FIG. 3, the control device (22) is equipped with a computational circuit composed of various processors and memory, etc. 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)]. In addition, various functions of the control device (22) may be realized by a single processor or by multiple processors of the same or different types.

[0041] In addition to the aforementioned thickness measuring device body (18), operating unit (24), and display unit (26), a memory unit (28) is connected to the control device (22). Furthermore, the memory unit (28) may be built into the control device (22). In this memory unit (28), in addition to the control program not shown in the control device (22), wafer information (29) corresponding to the object to be measured information of the present invention is stored in advance for each type of wafer (W).

[0042] Wafer information (29) is information regarding the actual dimensions, properties, and characteristics 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 different from the method using the thickness measuring device (12). v Wow, the refractive index n of a known wafer (W) and the refractive index temperature coefficient Δn t and the coefficient of linear thermal expansion α is included.

[0043] 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 an unillustrated control program stored in a memory unit (28).

[0044] The measurement control unit (30) operates in accordance with the input of a temperature measurement start operation to the operation unit (24) to perform thickness measurement of the wafer (W) by the thickness measuring device (12). Specifically, the measurement control unit (30) emits measurement light (L1) from the light source (18a), receives reflected light (L2) by the light receiving sensor (18b) and outputs the light receiving signal, and calculates the thickness L by the thickness calculation unit (18c). opt Execute the operation of.

[0045] The thickness acquisition unit (32) has a thickness calculation unit (18c) for thickness L opt When the operation is executed, the thickness L from this thickness calculation unit (18c) opt The calculation result is obtained and the calculation result is output to the temperature calculation unit (36).

[0046] The wafer information acquisition unit (34) corresponds to the object to be measured information acquisition unit of the present invention. This wafer information acquisition unit (34) operates, for example, in response to an input of a temperature measurement start operation, to acquire wafer information (29) from the memory unit (28) and output the wafer information (29) to the temperature calculation unit (36). Additionally, instead of acquiring wafer information (29) from the memory unit (28), the wafer information acquisition unit (34) may acquire wafer information (29) from an external server via a known communication network.

[0047] The temperature calculation unit (36) receives the thickness L input from the thickness acquisition unit (32). opt And, the wafer temperature is calculated based on the wafer information (29) input from the wafer information acquisition unit (34). Below, an example of the calculation of the wafer temperature by the temperature calculation unit (36) will be explained in detail.

[0048] As mentioned above, the thickness L of the wafer (W) opt is the actual thickness L v It is the thickness obtained by multiplying by the refractive index n of the wafer (W). For this reason, the actual thickness L v It is expressed by the following Equation 1.

[0049] [Equation 1]

[0050]

[0051] Here, the refractive index n has a temperature dependence, and this temperature dependence is the refractive index temperature coefficient Δn t It is known as 」. Also, the actual thickness L v There is also a temperature dependency, which is known as the "coefficient of linear thermal expansion α". For this reason, when the temperature change from a predetermined reference temperature T of the wafer (W) is ΔT, the above Equation 1 is expressed as Equation 2 below.

[0052] [Equation 2]

[0053]

[0054] In Equation 2 above, the refractive index n at the reference temperature T and the refractive index temperature coefficient Δn t is a known value as it is a parameter regarding the material of the wafer (W). Also, the coefficient of linear thermal expansion α is a known value as it is a parameter regarding the material of the wafer (W). Therefore, the aforementioned wafer information (29) (actual thickness L v , refractive index n, refractive index temperature coefficient Δn t and by obtaining the coefficient of linear thermal expansion α) in advance, thickness L opt Based on the wafer information (29), a temperature change ΔT can be derived as shown in Equation 3 below. Then, the wafer temperature can be calculated based on the derived temperature change ΔT and a known reference temperature T.

[0055] [Equation 3]

[0056]

[0057] The temperature calculation unit (36) receives 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.

[0058] In addition, in Equation 3 above, the refractive index temperature coefficient Δn t is approximately 100 times the magnitude of the linear thermal expansion coefficient α. For this reason, depending on the precision of the wafer temperature to be determined, the linear thermal expansion coefficient α can be simplified to α = 0.0. In this case, Equation 3 above is simplified as shown in Equation 4 below.

[0059] [Equation 4]

[0060]

[0061] FIG. 4 shows a wafer (W) made of silicon [refractive index n = 3.4, refractive index temperature coefficient Δn t = 2.0 × 10 -4 and actual thickness L v Thickness L in the case where = 0.777mm] opt This is a graph showing the relationship between and the temperature change ΔT. In addition, the graph of symbol 4A in Fig. 4 represents the linear thermal expansion coefficient α as α = 2.6 × 10⁻⁶ -6 Thickness L in the case of 」 opt It shows the relationship between and the temperature change ΔT. In addition, the graph of symbol 4B in Fig. 4 is for thickness L when the coefficient of linear thermal expansion α is simplified to “α=0.0”. opt It represents the relationship between and the temperature change ΔT.

[0062] Figure 5 is a graph showing the error between the graph of symbol 4A in Figure 4 and the graph of symbol 4B in Figure 4.

[0063] As shown in FIGS. 4 and 5, 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 minimal, so it was confirmed that there is no problem even if the linear thermal expansion coefficient α is simplified depending on the precision of the wafer temperature to be obtained. In this case, the calculation of the temperature change ΔT by the temperature calculation unit (36) is simplified, so the time required for calculating the wafer temperature is shortened.

[0064] [Operation of the non-contact temperature measuring device of the first embodiment]

[0065] FIG. 6 is a flowchart showing the flow of a non-contact temperature measurement method of a wafer (W) by a non-contact temperature measuring device (10) of the first embodiment. Additionally, wafer information (29) is assumed to be stored in a memory unit (28) in advance.

[0066] As shown in FIG. 6, when a temperature measurement start operation is input to the control unit (24) (step S1), 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). Then, the measurement control unit (30) executes a thickness measurement of the wafer (W) by the thickness measuring device (12). Accordingly, a measurement light (L1) is emitted from the light source (18a) and the measurement light (L1) is emitted from the sensor head (14) toward the surface (Wa) of the wafer (W) through the optical fiber cable (16) (step S2, corresponding to the light emission step of the present invention).

[0067] When a measurement light (L1) is emitted from the sensor head (14) toward the surface (Wa), reflected light (L2), including reflected light (L2A) reflected from the 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) through the optical fiber cable (16). Accordingly, the reception of the reflected light (L2) by the light receiving sensor (18b) and the output of the light reception signal are executed (step S3, corresponding to the light reception step of the present invention).

[0068] Next, the thickness calculation unit (18c) calculates the thickness L of the wafer (W) based on the light reception signal output from the light reception sensor (18b). opt The calculation is performed, and the result of the calculation is output to the temperature calculation unit (36) (step S4, corresponding to the thickness calculation step of the present invention). Accordingly, the thickness L of the wafer (W) opt It is measured non-contactually.

[0069] Meanwhile, the wafer information acquisition unit (34) acquires wafer information (29) from the memory unit (28) in response to the input of the temperature measurement start operation for the operation unit (24), and outputs the wafer information (29) to the temperature calculation unit (36) (step S5, corresponding to the step of acquiring information of the object to be measured in the present invention). In addition, the timing of the acquisition of wafer information (29) by the wafer information acquisition unit (34) is not particularly limited as long as it is before the calculation of the wafer temperature by the temperature calculation unit (36).

[0070] And, the temperature calculation unit (36) receives the thickness L input from the thickness calculation unit (18c). opt And, 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 the above 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).

[0071] As described above, the non-contact temperature measuring device (10) of the first embodiment has a thickness L of a wafer (W). opt Since the wafer temperature can be measured by non-contact measurement alone, the wafer temperature can be measured non-contact without being affected by electrical, magnetic, and mechanical noise, or by plasma that generates infrared radiation. As a result, the temperature of the wafer (W) can be measured simply and with high precision.

[0072] [Second embodiment]

[0073] 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 of a second embodiment. The non-contact temperature measuring device (10) of the first embodiment non-contact measures the wafer temperature using a single wavelength measuring light (L1), but the actual thickness L of the wafer (W) during the semiconductor manufacturing process v If the temperature changes significantly, there is a risk of an error in the measurement result of the wafer temperature. Therefore, the non-contact temperature measuring device (10) of the second embodiment non-contact measures the wafer temperature using a measuring light (L1) of multiple wavelengths (here, 2 wavelengths).

[0074] As shown in FIGS. 7 and 8, the non-contact temperature measuring device (10) of the second embodiment is basically the same configuration as the non-contact temperature measuring device (10) of the first embodiment, except that it is equipped with a thickness measuring device (12A) different from the thickness measuring device (12) of the first embodiment. For this reason, the same reference numerals are assigned to parts that are functionally or structurally identical to the first embodiment, and their descriptions are omitted.

[0075] The thickness measuring device (12A) measures the thickness L of the wafer (W) using measuring light (L1) of two different wavelengths (wavelength λ1, wavelength λ2). opt, λ1 and thickness L opt, λ2It measures non-contact. In addition to the aforementioned sensor head (14) and optical fiber cable (16), this thickness measuring device (12A) is equipped with an optical fiber coupler (17) and a thickness measuring device body (18-1, 18-2).

[0076] The optical fiber coupler (17) is, for example, a WDM (Wavelength Division Multiplexing) combiner / splitter. An optical fiber cable (16) (sensor head (14)) is connected to one end of the optical fiber coupler (17), and a thickness measuring device body (18-1, 18-2) is connected to the other end, respectively. The optical fiber coupler (17) combines (combines) the measurement light (L1) of wavelength λ1 incident from the thickness measuring device body (18-1) described later and the measurement light (L1) of wavelength λ2 incident from the thickness measuring device body (18-2) described later, and outputs it to the optical fiber cable (16) (sensor head (14)). Additionally, the optical fiber coupler (17) splits the reflected light (L2) of two wavelengths incident from the optical fiber cable (16), and emits the reflected light (L2) of wavelength λ1 to the thickness measuring device body (18-1), and emits the reflected light (L2) of wavelength λ2 to the thickness measuring device body (18-2).

[0077] The thickness measuring device body (18-1, 18-2) is basically the same configuration as the thickness measuring device body (18) of the first embodiment.

[0078] The light source (18a) of the thickness measuring device body (18-1) emits a measurement light (L1) of wavelength λ1, and the light source (18a) of the thickness measuring device body (18-2) emits a measurement light (L1) of wavelength λ2, which is different from wavelength λ1. These measurement light (L1) of wavelength λ1 and measurement light (L1) of wavelength λ2 are combined in an optical fiber coupler (17), then incident on a sensor head (14) through an optical fiber cable (16), and then emitted from the sensor head (14) toward the surface (Wa). Accordingly, reflected light (L2) of two wavelengths (wavelength λ1, wavelength λ2) is incident from the sensor head (14) through the optical fiber cable (16) to the optical fiber coupler (17) and split into reflected light (L2) of wavelength λ1 and reflected light (L2) of wavelength λ2. Then, reflected light (L2) of wavelength λ1 is emitted from the optical fiber coupler (17) to the thickness measuring device body (18-1), and reflected light (L2) of wavelength λ2 is emitted from the optical fiber coupler (17) to the thickness measuring device body (18-2).

[0079] The light receiving sensor (18b) of the thickness measuring device body (18-1) receives reflected light (L2) of 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 body (18-1) calculates the thickness L of the wafer (W) based on this light receiving signal. opt, λ1 ...is calculated. In addition, the light receiving sensor (18b) of the thickness measuring device body (18-2) receives reflected light (L2) of 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 body (18-2) calculates the thickness L of the wafer (W) based on this light receiving signal. opt, λ2 Calculate .

[0080] The measurement control unit (30) of the second embodiment, in response to the input of a temperature measurement start operation to the operation unit (24), emits measurement light (L1) from a light source (18a) for each thickness measuring device body (18-1, 18-2), receives reflected light (L2) by a light receiving sensor (18b) and outputs a light receiving signal, and calculates the thickness L by the thickness calculation unit (18c). opt, λk The operation [k=1, 2] is executed. Accordingly, for each wavelength of the measurement light (L1), the thickness L opt, λk It is measured non-contactually.

[0081] The thickness acquisition unit (32) of the second embodiment obtains the thickness L for each wavelength of the measurement light (L1) from the thickness measuring device body (18-1, 18-2). opt, λk The calculation results are obtained and output to the temperature calculation unit (36).

[0082] The temperature calculation unit (36) of the second embodiment, for each wavelength of the measurement light (L1), thickness L opt, λk Based on the wafer information (29), the temperature change ΔT is calculated in the same manner as in the first embodiment. 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. Below, an example of the calculation of the wafer temperature by the temperature calculation unit (36) of the second embodiment will be described in detail.

[0083] The refractive index n of the wafer (W) for each wavelength of the measurement light (L1) is the refractive index n λk In the case where [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 It is the thickness multiplied by. For this reason, the actual thickness L v It is expressed by the following Equation 5.

[0084] [Equation 5]

[0085]

[0086] And, refractive index nλk The temperature dependence of the refractive index temperature coefficient Δn t, λk In the case where [k=1, 2] is represented, the above Equation 5 is expressed as the following Equation 6.

[0087] [Equation 6]

[0088]

[0089] When the above Equation 6 is expanded for each wavelength of the measurement light (L1), it is expressed as the upper and lower equations of Equation 7 below.

[0090] [Equation 7]

[0091]

[0092] 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 is obtained from the above Equation 7.

[0093] [Equation 8]

[0094]

[0095] And, by modifying Equation 8 above, a temperature change ΔT can be derived as shown in Equation 9 below. Accordingly, just like in the first embodiment above, the wafer temperature can be calculated based on the derived temperature change ΔT and a known reference temperature T.

[0096] [Equation 9]

[0097]

[0098] In addition, the actual thickness L of the wafer (W) v It can be expressed in three formulas as shown in Equation 10 below. For this reason, by substituting the temperature change ΔT obtained from Equation 9 above into any one of the three formulas, the actual thickness L of the wafer (W) v It is saved.

[0099] [Equation 10]

[0100]

[0101] As for the flow of the non-contact temperature measurement method of a wafer (W) by the non-contact temperature measuring device (10) of the second embodiment, since it is basically the same as the flow described in FIG. 6 above, a detailed explanation is omitted here.

[0102] As described above, the non-contact temperature measuring device (10) of the second embodiment uses a measuring light (L1) of two wavelengths to measure the thickness L of a wafer (W). opt, λk By measuring the wafer temperature based on the measurement results and wafer information (29), the actual thickness L of the wafer (W) during the semiconductor manufacturing process v Even if the temperature changes significantly, the wafer temperature can be measured with high precision.

[0103] In addition, in the non-contact temperature measuring device (10) of the second embodiment above, wafer temperature measurement is performed using two wavelengths of measuring light (L1), but wafer temperature measurement may also be performed using three or more different wavelengths of measuring light (L1).

[0104] [Third Embodiment]

[0105] FIG. 9 is a schematic diagram of a non-contact temperature measuring device (10) of a third embodiment. The non-contact temperature measuring device (10) of each embodiment has a thickness L of a wafer (W). opt (Thickness L opt, λk The wafer temperature is calculated based on ) and wafer information (29), but due to doping treatment of the wafer (W), the wafer information (29) (refractive index n, refractive index temperature coefficient Δn t There are cases where the coefficient of linear thermal expansion α) becomes unclear. Therefore, the non-contact temperature measuring device (10) of the third embodiment measures the wafer temperature without using wafer information (29).

[0106] As shown in FIG. 9, the non-contact temperature measuring device (10) of the third embodiment is basically the same configuration as the first embodiment, except that correlation data (29A) is stored in the memory unit (28) instead of wafer information (29), the control unit (22) functions as a correlation data acquisition unit (35) instead of a wafer information acquisition unit (34), and the wafer temperature calculation method of the temperature calculation unit (36) is different. For this reason, the same reference numerals are assigned to parts that are functionally or structurally identical to the first embodiment, and their descriptions are omitted.

[0107] Correlation data (29A) is the thickness L of the wafer (W). opt This is data showing the correlation between the wafer temperature and the wafer temperature, and is stored in the memory unit (28) in advance for each type of wafer (W).

[0108] FIG. 10 is an explanatory diagram for explaining an example of a method for generating correlation data (29A). As shown in FIG. 10, when generating correlation data (29A), a temperature sensor (100) is attached to a wafer (W), and a data logger (102) is connected to the thickness measuring device body (18) and the temperature sensor (100).

[0109] 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 body (18) measures the thickness L of the wafer (W). opt This thickness L is continuously measured along with this thickness L opt The measurement results are continuously output to the data logger (102).

[0110] FIG. 11 is a diagram showing an example of recording data recorded by a data logger (102). As shown in FIG. 11, the data logger (102) continuously receives a wafer temperature (see reference numeral XIA) from a temperature sensor (100) and a wafer (W) thickness L continuously received from a thickness measuring device body (18).opt (Refer to symbol XIB) is recorded on the same time axis. In addition, the wafer temperature and thickness L by the data logger (102) opt The recording is performed repeatedly near the actual operating temperature.

[0111] FIG. 12 is a diagram showing an example of 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, the thickness L of the wafer (W) opt Correlation data (29A) (here, a formula) showing the correlation between and wafer temperature is obtained.

[0112] Additionally, instead of the formula shown in FIG. 12 as correlation data (29A), a data table may be generated. Alternatively, the wafer temperature and thickness L recorded by the data logger (102) may be used. opt Using the recorded data of as training data, and thickness L opt A machine learning model can be created with the wafer temperature as input and used as the correlation data (29A).

[0113] Returning to Fig. 9, 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, so a detailed description is omitted here.

[0114] The correlation data acquisition unit (35) operates, for example, in response to an input of a temperature measurement start operation, to acquire correlation data (29A) from the memory unit (28) and output the correlation data (29A) to the temperature calculation unit (36). Additionally, instead of acquiring correlation data (29A) from the memory unit (28), the correlation data acquisition unit (35) may acquire correlation data (29A) from an external server via a known communication network.

[0115] The temperature calculation unit (36) of the third embodiment receives the thickness L input from the thickness acquisition unit (32). opt Based on this, the wafer temperature is calculated by referring to the correlation data (29A) input from the correlation data acquisition unit (35).

[0116] FIG. 13 is a flowchart showing the flow of a non-contact temperature measurement method of a wafer (W) by a non-contact temperature measuring device (10) of the third embodiment. Additionally, the correlation data (29A) is assumed to be stored in the memory unit (28) in advance. Furthermore, since the processing from step S1 to step S4 is the same as that of the first embodiment described in FIG. 6 above, the explanation is omitted here.

[0117] As shown in FIG. 13, in response to the input of a temperature measurement start operation for the operation unit (24), the correlation data acquisition unit (35) acquires correlation data (29A) from the memory unit (28) and outputs the correlation data (29A) to the temperature calculation unit (36) (step S5A, corresponding to the correlation data acquisition step of the present invention). Furthermore, the timing of the acquisition of 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).

[0118] Next, the temperature calculation unit (36) receives the thickness L input from the thickness calculation unit (18c). opt Based on this, the wafer temperature is calculated by referring to the correlation data (29A) input from the correlation data acquisition unit (35) (step S6A, corresponding to the temperature calculation step of the present invention). By using the correlation data (29A), the temperature calculation unit (36) [calculates] thickness L opt The wafer temperature can be directly calculated from this.

[0119] As described above, in the non-contact temperature measuring device (10) of the third embodiment, the thickness L of the wafer (W) optSince the wafer temperature can be measured solely by non-contact measurement, the same effect as the non-contact temperature measuring device (10) of the first embodiment is obtained. In addition, in the third embodiment, thickness L opt Since the wafer temperature can be directly calculated from it, the wafer temperature can be calculated more simply and in a shorter time than in the first embodiment.

[0120] [etc]

[0121] In each of the above embodiments, the thickness L of the wafer (W) opt (Thickness L opt, λk A thickness measuring instrument (12, 12A) (see FIG. 1 and FIG. 7) is exemplified as a thickness measuring device for non-contact measuring (including), but the thickness L of the wafer (W) opt If optical non-contact measurement is possible, the configuration of the thickness gauge (12, 12A) can be appropriately changed.

[0122] In each of the above embodiments, a non-contact temperature measuring device (10) for measuring the temperature of a wafer (W) in a non-contact manner was described as an example, but the present invention can also be applied to a non-contact temperature measuring device (10) for measuring the temperature of various objects having light transmittance in a non-contact manner. Explanation of the symbols

[0123] 10… Non-contact temperature measuring 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 unit, 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, Lv … actual thickness, T… reference temperature, W… wafer, Wa… surface, Wb… back side, n… refractive index, n λk … refractive index, ΔT… temperature change, Δn t … refractive index, temperature coefficient, α… linear thermal expansion coefficient

Claims

Claim 1 A non-contact temperature measuring device for measuring a light-transmitting object having a surface and a back surface, comprising: a light-emitting unit that emits a measurement light toward the surface; a light-receiving unit that receives a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object from the surface and is reflected from the back surface opposite to the surface of the object, 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 is set as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is set as a second thickness; 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; and a temperature calculation unit that calculates the temperature of the object based on the second thickness calculated by the thickness calculation unit and the object information acquired by the object information acquisition unit. Claim 2 A non-contact temperature measuring device according to claim 1, wherein 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. Claim 3 A non-contact temperature measuring device according to claim 1 or 2, wherein 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 wavelength 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, 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 to be measured information. Claim 4 A non-contact temperature measuring device for measuring a light-transmitting object having a surface and a back surface, comprising: a light-emitting unit that emits a measurement light toward the surface; a light-receiving unit that receives a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object from the surface and is reflected from the back surface opposite to the surface of the object, 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 is set as a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is set as a second thickness; a correlation data acquisition unit that acquires correlation data in advance indicating the correlation between the second thickness and the temperature of the object; and a temperature calculation unit that calculates the temperature of the object by referring to the correlation data acquired by the correlation data acquisition unit based on the second thickness calculated by the thickness calculation unit. Claim 5 A non-contact temperature measurement method for measuring the temperature of a light-transmitting object having a surface and a back surface, comprising: a light emission step for emitting a measurement light toward the surface; a light reception step for receiving a light reception signal by receiving a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object from the surface and is reflected from the back surface opposite to the surface of the object; a thickness calculation step for calculating a second thickness based on the light reception signal output in the light reception step, wherein the actual thickness of the object is a first thickness and the thickness obtained by multiplying the first thickness by the refractive index of the object is a second thickness; a object information acquisition step for acquiring object information including the first thickness, the refractive index, and the refractive index temperature coefficient of the object; and a temperature calculation step for calculating the temperature of the object based on the second thickness calculated in the thickness calculation step and the object information acquired in the object information acquisition step. Claim 6 A non-contact temperature measurement method for measuring the temperature of a light-transmitting object having a surface and a back surface, comprising: a light emission step for emitting a measurement light toward the surface; a light reception step for receiving a light reception signal by receiving a reflected light of the measurement light reflected from the surface and a reflected light of the measurement light that passes through the interior of the object to be measured from the surface and is reflected from the back surface opposite to the surface of the object to be measured; a thickness calculation step for calculating a second thickness based on the light reception signal output in the light reception step, wherein 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 acquisition step for acquiring correlation data in advance that indicates the correlation between the second thickness and the temperature of the object to be measured; and a temperature calculation step for calculating the temperature of the object to be measured by referring to the correlation data acquired in the correlation data acquisition step, based on the second thickness calculated in the thickness calculation step.

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