Temperature measurement method and temperature measurement system

Abstract

The application belongs to the technical field of semiconductor manufacturing, and provides a temperature measuring method and a temperature measuring system. The method comprises the following steps: providing a semiconductor device, a thickness measuring device, a refractive index measuring device, and a theoretical correspondence between thickness and temperature; placing a to-be-tested piece on a base, controlling a heating device to heat the base, and controlling the thickness measuring device and the refractive index measuring device to respectively emit a first light beam and a second light beam to the to-be-tested piece; obtaining a real-time refractive index of the to-be-tested piece according to reflected light information of the second light beam passing through the to-be-tested piece, and calculating a real-time corrected thickness of the to-be-tested piece according to interference light information of the first light beam passing through the to-be-tested piece and the real-time refractive index; and calculating a real-time temperature of the to-be-tested piece according to the real-time corrected thickness and the theoretical correspondence between thickness and temperature. The method can realize direct temperature measurement of the to-be-tested piece without infrared temperature measurement, and fundamentally avoids the adverse effects of factors such as the base structure on the temperature measurement accuracy in traditional non-contact temperature measurement.

Description

A temperature measurement method and system Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a temperature measurement method and temperature measurement system. Background Technology

[0002] Temperature is a core process parameter affecting semiconductor manufacturing processes, such as epitaxial growth. Precise temperature control during the epitaxial growth of semiconductor material layers is a key factor in ensuring normal process operation and product quality. In semiconductor manufacturing equipment, taking Metal-organic Chemical Vapor Deposition (MOCVD) equipment as an example, the substrate is placed on a pedestal, and a heating device is positioned below the pedestal to heat it. Heat transfer from the pedestal to the substrate is then achieved. Infrared thermometry, as a non-contact temperature measurement method that can directly sample the substrate, is a commonly used temperature measurement technique in the field of semiconductor equipment measurement and control. Specifically, infrared radiation is received through the optical window of the process chamber. Using the intensity of the received infrared radiation and the spectral emissivity fed back from the surface of the substrate, the temperature of the substrate can be obtained based on Planck's law of radiation.

[0003] Optically transparent substrates have very low emissivity in the infrared band, while the base supporting the substrate, such as a graphite base, has relatively high emissivity. The infrared radiation emitted by the base will pass through the optically transparent substrate and be received by the infrared thermometer. In other words, what the infrared thermometer actually measures is the temperature of the base.

[0004] However, even if the recesses supporting the substrate on the substrate have good adhesion to the bottom surface of the substrate, during the growth of the semiconductor material layer, stress can cause warping of the substrate, as shown in Figures 5 and 6, resulting in a space filled with gaseous medium between the substrate and the recesses. Furthermore, to mitigate or even avoid substrate warping, existing technologies, as shown in Figure 4, modify the recess structure on the substrate, making the substrate supported by edge support. However, this modified recess structure also results in a space filled with gaseous medium between the substrate and the recesses, causing the infrared radiation emitted by the substrate to be reflected multiple times at the interfaces between the substrate and the gaseous medium, and between the gaseous medium and the substrate. The interference between these reflections affects the accuracy of infrared thermometry. Moreover, since the gaseous medium has lower thermal conductivity than the substrate and the substrate, it significantly hinders heat conduction, resulting in a large temperature difference between the substrate and the substrate.

[0005] Therefore, a new temperature measurement method is urgently needed to solve the above-mentioned problems of existing technologies. Summary of the Invention

[0006] The purpose of this application is to provide a temperature measurement method and system that does not rely on infrared thermometry or a substrate-supported method, which is beneficial for directly and accurately measuring the real-time temperature of the test piece rather than the test piece.

[0007] To achieve the above objectives, the temperature measurement method provided in this application includes at least the following steps:

[0008] S1: Provides a semiconductor device, a thickness measuring device, a refractive index measuring device, and a theoretical relationship between thickness and temperature, wherein the semiconductor device includes a base and a heating device;

[0009] S2: Place the optically transparent test piece on the base, control the heating device to heat the base, and control the thickness measuring device and the refractive index measuring device to emit a first beam with a bandwidth of no more than 0.1 nanometers and a second beam with a bandwidth ratio of no less than 100:1 and the same as the center wavelength of the first beam to the light-receiving surface of the test piece, respectively.

[0010] S3: Obtain the real-time refractive index n of the test piece based on the reflected light information of the second beam passing through the test piece. Calculate the real-time corrected thickness d of the test piece based on the interference light information of the first beam passing through the test piece and the real-time refractive index n. c ;

[0011] S4: Based on the real-time correction thickness d c Based on the theoretical relationship between the thickness and temperature, the real-time temperature T of the test piece is calculated.

[0012] Optionally, the theoretical relationship between the thickness and temperature is: d = d0[1 + α(T - T0)], where d is the thickness, d0 is the initial thickness, T is the real-time temperature, T0 is the room temperature, and α is the coefficient of thermal expansion;

[0013] Step S1 further includes providing the coefficient of thermal expansion α and the initial thickness d0 at room temperature T0 of the test piece;

[0014] In step S4, the real-time corrected thickness d is determined. c The real-time temperature T is calculated from the ambient temperature T0, the corresponding initial thickness d0, and the theoretical relationship between the thickness and temperature.

[0015] Optionally, both the light-receiving surface and the back-light-receiving surface of the test piece are polished.

[0016] Optionally, the thickness of the test piece shall not exceed 10 mm.

[0017] Optionally, the bandwidth of the second beam is not less than 10 nanometers.

[0018] Optionally, the first beam is a laser, the second beam is a beam emitted by a blue LED, and the center wavelength range of the first beam and the second beam is 405 nm ± 5 nm.

[0019] Optionally, during step S2, the first beam and the second beam are switched on and off using mechanical chopping or direct electrical modulation, and the refractive index measuring device is controlled to be in a closed state while the thickness measuring device emits the first beam.

[0020] Optionally, the step of obtaining the real-time refractive index n of the test specimen includes:

[0021] The real-time reflectivity R of the test piece is obtained using the reflected light information of the second beam;

[0022] The real-time refractive index n is obtained based on the measured reflectivity R and the correspondence between reflectivity and refractive index.

[0023] Optionally, the second beam exits perpendicularly to the light-receiving surface of the test piece, and the relationship between the reflectivity and refractive index is: R=[(n-1) / (n+1)] 2 .

[0024] Optionally, the corrected thickness d of the test piece is obtained. c The steps include:

[0025] The real-time optical path difference L is obtained based on the corresponding interference light information fed back by the first beam;

[0026] The real-time corrected thickness d is obtained based on the real-time optical path difference L and the real-time refractive index n. c .

[0027] Optionally, the first beam exits perpendicular to the light-receiving surface of the test piece, and the real-time corrected thickness is calculated using the following formula: d c =L / (2n).

[0028] Optionally, the base includes a recess, and the inner sidewall of the recess is provided with a support platform along the circumferential direction for supporting the edge of the test piece, so that there is a gap between the bottom surface of the test piece and the inner bottom surface of the recess.

[0029] Optionally, the test piece in step S2 is a substrate, and after step S4, the following preset process steps are further performed:

[0030] The heating device is controlled to heat the base until the process isothermal state is reached, and process gas is supplied to the reaction chamber where the test piece is located, so as to grow an optically transparent homogeneous material layer on the light-receiving surface of the test piece.

[0031] During the execution of the preset process steps, step S2 controls the thickness measuring device and the refractive index measuring device to emit a first beam with a bandwidth of no more than 0.1 nanometers and a second beam with a bandwidth ratio of no less than 100:1 and the same as the center wavelength of the first beam, respectively, onto the light-receiving surface of the test piece; and step S3 obtains the real-time growth thickness of the homogeneous material layer.

[0032] This application also provides a temperature measuring system for performing any of the temperature measuring methods described above, the temperature measuring system comprising:

[0033] The thickness measuring device is configured to emit a first beam with a bandwidth not exceeding 0.1 nanometers and receive interference light information fed back from the first beam.

[0034] The refractive index measuring device is configured to emit a second beam with a bandwidth ratio of not less than 100:1 to the first beam and with the same center wavelength as the first beam, and to receive reflected light information fed back from the second beam.

[0035] Optionally, the temperature measurement system further includes a main control device that communicates with the thickness measuring device and the refractive index measuring device to obtain the real-time refractive index n of the test piece based on the reflected light information of the second beam, and to calculate the real-time corrected thickness d of the test piece based on the interference light information of the first beam and the real-time refractive index n. c ;

[0036] The main control device has a pre-stored theoretical correspondence between thickness and temperature, so as to correct the thickness d in real time. c Based on the theoretical relationship between the thickness and temperature, the real-time temperature T of the test piece is calculated.

[0037] Compared with existing technologies, the temperature measurement method and system provided in this application have at least the following advantages:

[0038] In the temperature measurement method of this application, a first beam and a second beam with the same center wavelength are emitted from a thickness measuring device and a refractive index measuring device onto the light-receiving surface of the test piece, respectively. The real-time refractive index n of the test piece and the real-time corrected thickness d after correction using the real-time refractive index n are obtained based on the light information fed back by the first beam and the second beam after passing through the test piece. c And adjust the thickness d in real time cThe real-time temperature T of the test piece is obtained by inverting the theoretical correspondence between thickness and temperature. The entire temperature measurement process does not require infrared thermography, realizing direct measurement of the test piece. Furthermore, the optical information obtained from the first and second beams can directly reflect the real-time physical information of the test piece, fundamentally avoiding the adverse effects of traditional non-contact temperature measurement methods, such as infrared thermography, on the accuracy of temperature measurement. Further, by controlling the bandwidth of the first beam to not exceed 0.1 nanometers, the bandwidth ratio of the second beam to the first beam to be not less than 100:1, and ensuring that the center wavelengths of the first and second beams are consistent, the interference optical information related to thickness and refractive index obtained from the narrow-bandwidth first beam through the test piece can be effectively combined with the real-time refractive index n obtained from the wide-bandwidth second beam through the test piece. The real-time refractive index n is then used to correct the thickness in the interference optical information, thereby obtaining the real-time corrected thickness d. c .

[0039] The temperature measurement system provided in this application is used to perform the above-mentioned temperature measurement method, and therefore has the same beneficial effects as described above. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 shows a flowchart of a temperature measurement method provided in this application.

[0042] Figure 2 shows a schematic diagram of the principle structure of the semiconductor equipment and optical measurement device in a temperature measurement method provided in this application.

[0043] Figure 3 shows a schematic diagram illustrating the working principle of the optical measuring device in a temperature measurement method provided in this application.

[0044] Figure 4 shows a schematic diagram of the base with a recess in a temperature measurement method provided in this application.

[0045] Figures 5 and 6 show schematic diagrams of the structure in the prior art where the substrate warps downward and upward on a base with recesses, respectively.

[0046] Figure 7 shows a waveform diagram of the unmodulated signal emitted by the optical measuring device in a temperature measurement method provided in this application.

[0047] Figure 8 shows a waveform diagram of the modulation signal in a temperature measurement method provided in this application.

[0048] Figure 9 shows a waveform diagram of the modulated signal in a temperature measurement method provided in this application.

[0049] Figure 10 shows a schematic diagram of the principle structure of interference of the first beam on the surface of the test piece in a temperature measurement method provided in this application.

[0050] Figure 11 shows a schematic diagram of the principle structure of an optical lens group in a temperature measurement system provided in this application.

[0051] Figure 12 shows the relationship between refractive index and temperature obtained by using a temperature measuring instrument to collect infrared temperature information and using an ellipsometer to measure the refractive index.

[0052] Illustration of reference numerals in the attached diagram:

[0053] 100. Semiconductor equipment; 11. Base; 111. Recess; 1111. Support platform; 12. Heating device; 13. Test piece; 211. Thickness measuring device; 2111. First light source; 2112. First information detection unit; 212. Refractive index measuring device; 2121. Second light source; 2122. Second information detection unit; 213. Optical lens group; 2131. First beam splitter; 2132. Second beam splitter; 2133. Third beam splitter; 2134. First polarizer; 2135. Second polarizer; 2136. Third polarizer; 22. Main control device. Detailed Implementation

[0054] To make the technical objectives, technical solutions, and technical effects of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0056] In the description of this application, it should be noted that the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with an implementation or example, which are included in at least one implementation or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same implementation or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more implementations or examples.

[0057] Example 1

[0058] This invention provides a temperature measurement method for measuring the temperature of a test piece 13. Referring to Figures 1 to 3, the temperature measurement method includes steps S1 to S4, specifically including:

[0059] S1: Provides a semiconductor device 100, a thickness measuring device 211, a refractive index measuring device 212, and a theoretical correspondence between thickness and temperature. The semiconductor device 100 includes a base 11 and a heating device 12. The thickness measuring device 211 is used to emit a first light beam and receive the optical information fed back by the first light beam. The refractive index measuring device 212 is used to emit a second light beam and receive the optical information fed back by the second light beam.

[0060] S2: Place the optically transparent test piece 13 on the base 11, control the heating device 12 to heat the base 11, and control the thickness measuring device 211 and the refractive index measuring device 212 to emit a first beam and a second beam to the light-receiving surface of the test piece 13, respectively; the bandwidth of the first beam is no more than 0.1 nanometers, the bandwidth ratio of the second beam to the first beam is no less than 100:1, and the center wavelength of the second beam is consistent with that of the first beam;

[0061] S3: Obtain the real-time refractive index n of the test piece 13 based on the reflected light information of the second beam passing through the test piece 13. Calculate the real-time corrected thickness d of the test piece 13 based on the interference light information of the first beam passing through the test piece and the real-time refractive index n. c ;

[0062] S4: Based on real-time thickness correction d c Based on the theoretical relationship between the thickness and temperature, the real-time temperature T of the test piece 13 is calculated.

[0063] In this embodiment, a first light beam and a second light beam are emitted from a thickness measuring device 211 and a refractive index measuring device 212 onto the light-receiving surface of the test piece 13, respectively. Based on the light information fed back by the first and second light beams after passing through the test piece 13, the real-time refractive index n of the test piece 13 and the real-time corrected thickness d after correction using the real-time refractive index n are obtained. cAccording to the real-time correction thickness d c Based on the theoretical relationship between thickness and temperature, the real-time temperature T of the test piece 13 can be obtained by inversion. The entire temperature measurement process does not rely on external temperature sensors or infrared temperature measurement, realizing direct measurement of the test piece 13. Furthermore, the acquired light information can accurately reflect the real-time physical information of the test piece 13, fundamentally avoiding the adverse effects of the base structure on the accuracy of temperature measurement in traditional non-contact temperature measurement methods such as infrared temperature measurement.

[0064] Furthermore, in the temperature measurement method of this embodiment, the center wavelengths of the first beam and the second beam are consistent, the bandwidth of the first beam does not exceed 0.1 nanometers, and the bandwidth ratio of the second beam to the first beam is not less than 100:1. This allows for the effective combination of the interference light information related to thickness and refractive index obtained by the narrow-bandwidth first beam through the test piece 13 and the real-time refractive index n obtained by the wide-bandwidth second beam through the test piece 13. The real-time refractive index n is then used to correct the thickness in the interference light information to obtain the real-time corrected thickness d. c Specifically, thickness measurement is performed using a first light beam with a bandwidth of no more than 0.1 nanometers. The strong coherence and monochromaticity of this first beam allow for accurate characterization of the thickness information between the upper and lower surfaces through interference. The real-time reflectivity obtained by measuring using a second beam with a wide bandwidth characterizes the material's ability to reflect light. Conversely, if reflectivity is measured using a first beam with a bandwidth of no more than 0.1 nanometers, the result is not the reflectivity of the material itself, but rather a reflectance that is also related to the material's thickness and other factors.

[0065] In step S1, referring to Figures 2 and 3, the semiconductor device 100 is provided with a base 11 and a heating device 12 for heating. The heating device 12 is located below the base 11 to heat the base 11. The test piece 13 is placed on the base 11. The semiconductor device 100 may be provided with a reaction chamber. Both the base 11 and the heating device 12 are located in the reaction chamber. The heating device 12 can adjust the temperature of the test piece 13 and affect the temperature distribution in the reaction chamber. Optionally, referring to Figure 4, the upper surface of the base 11 may be provided with a recess 111. The inner sidewall of the recess 111 is provided with a support platform 1111 for supporting the edge of the test piece 13 along the circumferential direction, so that there is a gap between the bottom surface of the test piece 13 and the inner bottom surface of the recess 111, thereby enabling the base 11 to provide edge support for the test piece 13. A gas injection device may also be provided at the top of the reaction chamber. The gas injection device is positioned opposite to the top surface of the base 11 and is used to inject process gas into the reaction chamber. Optionally, a gas passage is provided at the top of the reaction chamber, and the gas injection device injects process gas into the reaction chamber through the gas passage to grow an optically transparent homogeneous material layer on the light-receiving surface of the test piece 13.

[0066] In this embodiment, the first light beam is a laser, and the thickness measuring device 211 may include a laser or other suitable type of light-emitting device to emit laser light as the first light beam; the second light beam is blue light, and the refractive index measuring device 212 may include a blue LED or other suitable type of light-emitting device to emit blue light as the second light beam. The specific structures of the thickness measuring device 211 and the refractive index measuring device 212 can be referred to the prior art, and will not be described in detail in this embodiment.

[0067] In an optional embodiment, the center wavelength range of the first beam and the second beam is 405 nm ± 5 nm, specifically, it can be 400 nm, 403 nm, 405 nm, 407 nm, 410 nm, or other suitable wavelength values. When a preset semiconductor process is performed using the semiconductor device 100, during the heating process inside the reaction chamber, the objects inside the reaction chamber will radiate electromagnetic waves of a certain wavelength. The base 11 supporting the test piece 13, such as a graphite base, has a high emissivity in the infrared band. By controlling the center wavelength of the first beam and the second beam to be between the violet band and the blue band, it is possible to prevent the wavelength from being too small and the energy from being too high, which would affect the environment inside the reaction chamber (for example, the thermal effect of the high-energy beam on the reaction atmosphere inside the reaction chamber, making the reaction atmosphere prone to thermal decomposition), or the wavelength from being too large and the energy from being too low, which would cause strong interference to the measurement process due to high-temperature infrared radiation.

[0068] In some specific embodiments, the first beam is a laser, and the second beam is a beam emitted by a blue LED.

[0069] In this embodiment, the bandwidth of the first beam is no more than 0.1 nanometers, and the bandwidth of the second beam is no less than 10 nanometers. By giving the first beam a narrow spectral width, it helps to improve measurement accuracy and reduce the influence of background noise. Giving the second beam a wide spectral width can help provide fast and wide-range scanning while meeting measurement accuracy requirements.

[0070] Furthermore, the center wavelength of the first beam is the same as that of the second beam, so as to ensure that the interference light information related to thickness and refractive index obtained by the first beam through the test piece 13 can be effectively combined with the real-time refractive index n obtained by the second beam through the test piece 13.

[0071] In this embodiment, the thickness of the test piece 13 does not exceed 10 mm. If the thickness of the test piece 13 is too large, it will easily lead to an excessive temperature difference between its top surface and the top surface, resulting in an obvious temperature gradient and thus affecting the accuracy of temperature measurement.

[0072] In this embodiment, the test piece 13 is a substrate. In some embodiments, the optically transparent test piece 13 is, for example, a sapphire substrate, specifically, a sapphire substrate that is substantially transparent to light of 200 nanometers to 5 micrometers. In some embodiments, the optically transparent test piece 13 may also be, for example, a silicon substrate, specifically, a silicon substrate that is substantially transparent to light of 1.1 micrometers to 6 micrometers.

[0073] Optionally, the test piece 13 is an optically transparent structure with double-sided polishing, that is, both the light-receiving surface and the back-lighting surface of the test piece 13 are polished, so that the test piece 13 is suitable for optical measurement and helps to improve measurement accuracy.

[0074] In step S2, the optically transparent test piece 13 is placed on the base 11 in the semiconductor device 100, and the thickness measuring device 211 and the refractive index measuring device 212 are controlled to emit a first beam and a second beam towards the test piece 13, respectively. The first beam and the second beam can be emitted obliquely to the light-receiving surface of the test piece 13 or perpendicularly to the light-receiving surface of the test piece 13. Preferably, the first beam and the second beam are emitted perpendicularly to the test piece 13 to facilitate optical thickness measurement and refractive index measurement of the test piece 13, reduce the difficulty of subsequent data processing, and improve measurement accuracy.

[0075] In this embodiment, the first beam emitted by the thickness measuring device 211 and the second beam emitted by the refractive index measuring device 212 can be either unmodulated beams or modulated beams. Optionally, in step S2, the first and second beams are modulated by mechanical chopping or direct electrical modulation, and the refractive index measuring device 212 is kept in a closed state during the emission of the first beam from the thickness measuring device 211, so that both the first and second beams emitted to the test piece are modulated beams, while preventing the second beam emitted by the refractive index measuring device 212 from interfering with the measurement process of the first beam. By modulating the first and second beams, DC and background radiation noise can be effectively suppressed, which helps to extract a pure measurement signal and improves measurement accuracy and anti-interference capability. The specific implementation of mechanical chopping or direct electrical modulation is a conventional technique in the art.

[0076] Figures 7 to 9 exemplarily illustrate the waveforms of an optical signal emitted by a thickness measuring device 211 or a refractive index measuring device 212 before and after modulation. Figure 7 shows the waveform of the unmodulated signal emitted by the thickness measuring device 211 or the refractive index measuring device 212 over time. The blue dashed line represents the actual signal emitted by the thickness measuring device 211 or the refractive index measuring device 212, the red dashed line represents the background signal, and the black solid line represents the total signal of the actual and background signals. It is evident that the background signal strongly interferes with the actual signal. Figure 8 shows the modulation signal used to modulate the actual signal shown in Figure 7. The modulation signal is a square wave with a frequency of 10 kHz and a duty cycle of 50%. Figure 9 shows the waveform of the modulated signal over time. The blue dashed line represents the actual signal before modulation, the magenta dashed line represents the background signal after modulation, the red dashed line represents the actual signal after modulation, and the black solid line represents the total signal after modulation. It is evident that the signal after on / off modulation effectively suppresses background noise.

[0077] Step S3, the step of obtaining the real-time refractive index n of the test piece 13, includes: obtaining the real-time reflectivity R using the reflected light information of the second beam; and obtaining the real-time refractive index n based on the real-time reflectivity R and the correspondence between reflectivity and refractive index. Specifically, the reflected light information of the second beam includes the real-time reflected light intensity I of the second beam passing through the test piece 13. _ref According to the real-time reflected light intensity I _re The real-time reflectivity of the test piece 13 to the second beam can be calculated, and then the real-time refractive index n of the test piece 13 can be calculated according to the Fresnel reflection formula.

[0078] In an optional embodiment, step S1 further includes: providing the initial refractive index n0 of the test piece; before executing step S2 to control the heating device to heat the base, it further includes: acquiring the initial reflected light intensity I of the test piece. _ref0 In step S3, the real-time reflectivity R is calculated based on the initial refractive index n0, the initial reflected light intensity I0, and the reflected light information fed back by the second beam.

[0079] In an optional embodiment, the second beam exits perpendicularly to the light-receiving surface of the test piece. In the case of perpendicular incidence, the relationship between reflectivity and refractive index can be simplified to: R = [(n-1) / (n+1)] 2 .

[0080] The refractive index of the actual test piece is affected by the temperature inside the reaction chamber. Existing technologies typically use a method of fitting the refractive index-temperature relationship at different temperatures to obtain the real-time refractive index. However, as mentioned earlier, the heating device 12 is located below the base 11 and is designed to heat the base 11. Existing technologies, whether using thermocouples near the base or infrared thermometry, obtain temperatures close to the temperature of the base 11 rather than the temperature of the test piece, especially for optically transparent test pieces. Therefore, conventional refractive index measurement methods, even if they fit the relationship between the refractive index n and the real-time temperature T, do not establish a corresponding relationship between the refractive index and the temperature of non-optically transparent test pieces. This makes it impossible to accurately measure the optically transparent test piece inside the reaction chamber in this embodiment.

[0081] Furthermore, taking the fitting of the real-time refractive index of an optically transparent test piece with infrared temperature measurement data as an example, even with this fitting method, the relationship between the obtained real-time refractive index n and the real-time temperature T of the infrared temperature measurement data shows that n changes very slightly with the real-time temperature T, with the difference only reflected in the change of the last decimal place, indicating insufficient reliability of the fitting. For example, taking a double-sided polished sapphire substrate placed in a graphite base cavity as an example, the heating device 12 is controlled to heat the graphite base, and an infrared temperature measurement instrument is used to collect infrared temperature information. The temperature measurement instrument can be, for example, a non-contact multi-channel fiber optic temperature measuring instrument, and the refractive index is measured using an ellipsometer. The relationship between the obtained refractive index and temperature is shown in Figure 12.

[0082] Therefore, in this embodiment, the refractive index of the test piece 13 is directly measured based on the initial reflected light intensity of the test piece and the reflected light information fed back in real time by the second beam. This measurement result can reflect the real-time physical information of the test piece, realizing the accurate measurement of the refractive index of the test piece. The thickness is corrected by using the real-time refractive index n, and the real-time temperature of the test piece is calculated by using the obtained real-time corrected thickness and the theoretical correspondence between thickness and temperature.

[0083] In step S3, the real-time corrected thickness d of the test piece is calculated. c The steps include: obtaining the real-time optical path difference L based on the corresponding interference light intensity information fed back by the first beam; and obtaining the real-time corrected thickness d based on the real-time optical path difference L and the real-time refractive index n. c .

[0084] In step S4, the test piece 13 has a light-receiving surface and a backlight surface arranged opposite to each other. The first light beam is emitted to the light-receiving surface of the test piece 13. The first light beam reflected from the light-receiving surface of the test piece 13 interferes with the first light beam reflected from the backlight surface of the test piece 13 to form an interference beam. The intensity change of the interference beam is detected by the thickness measuring device 211 to obtain the interference light information. The optical path difference between the two reflected beams of the first beam can be calculated based on the interference light information, and is denoted as the real-time optical path difference L.

[0085] Thickness measuring device 211, such as a laser interferometric thickness gauge, wherein the pre-stored refractive index n0 is a constant value. Its principle is based on conventional techniques in the field. For example, referring to Figure 10, the light intensity is denoted as I. The light intensity of the two reflected beams of the first beam and the real-time optical path difference L have the following relationship: I = I1 + I2 + 2cos(2πL / λ0)(I1I2) 0.5 In this context, I1 and I2 represent the light intensities of the first beam reflected from the light-receiving and back-light-receiving surfaces of the test piece 13, respectively, and λ0 is the center wavelength of the first beam. By detecting changes in the interference beam, such as the movement of extreme points or phase changes, the real-time optical path difference L can be calculated. Then, based on the incident angle of the first beam, the thickness d of the test piece 13 can be calculated. For example, in the case of normal incidence of the first beam, the thickness d = L / (2n0). It is evident that this thickness d is obtained based on a pre-stored refractive index n0 with a specific assignment. However, as mentioned earlier, the refractive index n is related to the chamber temperature; directly using the thickness measurement device 211 to obtain the measured thickness value will introduce measurement errors. Therefore, it is necessary to calculate the real-time corrected thickness d of the test piece based on the interference light information of the first beam passing through the test piece and the real-time refractive index n. c .

[0086] In an optional embodiment, the first beam exits perpendicular to the light-receiving surface of the test piece 13, and the real-time corrected thickness can be calculated using the following formula: d c =L / (2n).

[0087] In step S1, the theoretical relationship between thickness and temperature is: d = d0[1 + α(T - T0)], where d is the thickness, d0 is the initial thickness, T is the real-time temperature, T0 is the room temperature, and α is the coefficient of thermal expansion. Step S1 may also include the following steps: providing the coefficient of thermal expansion α of the test piece and the initial thickness d0 at room temperature T0.

[0088] The initial thickness d0 can be obtained by contact or non-contact thickness measurement of the test piece 13 at room temperature T0. The specific measurement method can refer to the existing technology. In this embodiment, the thickness measuring device 211 is used to measure the test piece 13 to obtain the initial thickness d0 of the test piece 13.

[0089] In step S4, the thickness d is corrected in real time. c The real-time temperature T of the test piece 13 is calculated using the ambient temperature T0 and the corresponding initial thickness d0, as well as the theoretical relationship between thickness and temperature.

[0090] In this embodiment, after step S4 is completed, the following preset process steps may be performed: controlling the heating device 12 to heat the base 11 until a constant process temperature is reached, and providing process gas into the reaction chamber where the test piece 13 is located, so as to grow an optically transparent homogeneous material layer on the light-receiving surface of the test piece 13. The type of process gas and the process for growing the homogeneous material layer can be selected according to the applicability of the process requirements. The method of controlling the heating device to heat the base until a constant process temperature is reached is a conventional technique in the art, such as PLC temperature control.

[0091] During the execution of the preset process steps, step S2 controls the thickness measuring device 211 and the refractive index measuring device 212 to emit a first beam with a bandwidth of no more than 0.1 nanometers and a second beam with a bandwidth ratio of no less than 100:1 and the same center wavelength as the first beam to the light-receiving surface of the test piece 13, respectively; and step S3 obtains the real-time growth thickness of the homogeneous material layer. Specifically, based on the real-time corrected thickness of the test piece 13 calculated in step S3 and the thickness measured by the thickness measuring device 211, the real-time growth thickness of the homogeneous material layer grown on the test piece 13 is calculated.

[0092] In the temperature detection method of this embodiment, by limiting the center wavelength range of the first beam and the second beam, the influence of background noise on the measurement accuracy can be reduced, while preventing interference with the environment inside the reaction chamber. By modulating the first beam and the second beam, DC and background radiation noise can be further suppressed, improving measurement accuracy and anti-interference capability. Furthermore, by using the first beam and the second beam with the same center wavelength, direct measurement of the test piece 13 can be achieved, and the acquired optical information can accurately reflect the real-time physical information of the test piece 13. The entire measurement process does not rely on an external temperature sensor, nor does it require infrared temperature measurement, fundamentally avoiding the adverse effects of factors such as the base structure on the temperature measurement accuracy in traditional non-contact temperature measurement.

[0093] Example 2

[0094] This embodiment provides a temperature measurement system for performing any of the temperature measurement methods in Embodiment 1. Referring to FIG3, the temperature measurement system includes at least a thickness measuring device 211 and a refractive index measuring device 212.

[0095] In this embodiment, the thickness measuring device 211 is used to emit a first light beam to the test piece 13 placed in the semiconductor device 100. The thickness measuring device 211 is configured to emit a first light beam with a bandwidth not exceeding 0.1 nanometers and to receive interference light information fed back from the first light beam. The refractive index measuring device 212 is used to emit a second light beam to the test piece 13. The refractive index measuring device 212 is configured to emit a second light beam with a bandwidth ratio of not less than 100:1 to the first light beam and consistent with the center wavelength of the first light beam, and to receive reflected light information fed back from the second light beam.

[0096] In this embodiment, referring to FIG2, the temperature measurement system further includes a main control device 22, which is communicatively connected to the thickness measuring device 211 and the refractive index measuring device 212. The main control device 22 obtains the real-time refractive index n of the test piece based on the reflected light information of the second beam, and calculates the real-time corrected thickness d of the test piece based on the interference light information of the first beam and the real-time refractive index n. c The main control device 22 has a pre-stored theoretical relationship between thickness and temperature, which is used to adjust the thickness d in real time. c Based on the theoretical relationship between thickness and temperature, the real-time temperature T of the test piece 13 was calculated.

[0097] In an optional embodiment, the semiconductor device 100 is provided with a reaction chamber for performing a preset semiconductor process. For example, the semiconductor device can be a semiconductor epitaxy device. The base 11 and the heating device 12 are both located in the reaction chamber. A gas injection device is provided at the top of the reaction chamber. The gas injection device is disposed opposite to the top surface of the base 11. A gas passage of the gas injection device is provided at the top of the reaction chamber for introducing process gas into the reaction chamber. The first beam and the second beam are vertically emitted to the test piece 13 through the gas passage of the gas injection device.

[0098] In this embodiment, referring to FIG11, the thickness measuring device 211 includes at least a first light source 2111 and a first information detection unit 2112. The first light source 2111 is used to emit a first light beam, and the first information detection unit 2112 is used to detect the interference light signal fed back by the first light beam through the test piece 13. The refractive index measuring device 212 includes at least a second light source 2121 and a second information detection unit 2122. The second light source 2121 is used to emit a second light beam, and the second information detection unit 2122 is used to detect the reflected light signal fed back by the second light beam through the test piece 13.

[0099] In this embodiment, the thickness measuring device 211 and the refractive index measuring device 212 can be separate thickness measuring devices and refractive index measuring devices, or they can constitute an integrated measurement system. Optionally, the thickness measuring device 211 and the refractive index measuring device 212 constitute an integrated measurement system. Referring also to FIG11, the optical measuring device 21 further includes an optical lens group 213, which includes at least a first beam splitter 2131, a second beam splitter 2132, a third beam splitter 2133, a first polarizer 2134, and a second polarizer 2135. The first beam emitted from the first light source 2111 is perpendicularly emitted to the test piece 13 via the first beam splitter 2131 and the second beam splitter 2132. The first beam reflected by the test piece 13 is then emitted to the first information detection unit 2112 via the second beam splitter 2132, the third beam splitter 2133, and the first polarizer 2134. The second beam emitted from the second light source 2121 is perpendicularly emitted to the test piece 13 via the first beam splitter 2131 and the second beam splitter 2132. The second beam reflected by the test piece 13 is emitted to the second information detection unit 2122 via the second beam splitter 2132, the third beam splitter 2133, and the second polarizer 2135.

[0100] In some embodiments, the first light beam emitted from the first light source 2111 passes through the first beam splitter 2131 and is reflected by the second beam splitter 2132 before being emitted vertically to the test piece 13. The first light beam reflected by the test piece 13 passes through the second beam splitter 2132 and is reflected by the third beam splitter 2133 before being emitted through the first polarizer 2134 and emitted to the first information detection unit 2112. The second light beam emitted from the second light source 2121 is reflected by the first beam splitter 2131 before being emitted to the second beam splitter 2132. After being reflected by the second beam splitter 2132, it is emitted vertically to the test piece 13. The second light beam reflected by the test piece 13 passes through the second beam splitter 2132, the third beam splitter 2133, and the second polarizer 2135 in sequence before being emitted to the second information detection unit 2122.

[0101] In some embodiments, the polarization direction of the first polarizer 2134 is perpendicular to the polarization direction of the second polarizer 2135.

[0102] In some embodiments, the optical lens group 213 may further include a third polarizer 2136, which is located between the first light source 2111 and the first beam splitter 2131. The polarization direction of the third polarizer 2136 is perpendicular to the first polarizer 2134. The first light beam emitted from the first light source 2111 passes through the third polarizer 2136 and is emitted to the first beam splitter 2131.

[0103] In some embodiments, the thickness measuring device 211 is further provided with a first modulator for modulating the first light beam emitted by the first light source 2111 so that the first light beam is a modulated beam, and the refractive index measuring device 212 is further provided with a second modulator for modulating the second light beam emitted by the second light source 2121 so that the second light beam is a modulated beam. The first modulator and the second modulator can be mechanical choppers or other suitable modulation devices or modulation circuits, as can be found in the prior art. The modulation signals of the first modulator and the second modulator can be square waves of a specific frequency or other suitable types of modulation signals.

[0104] The temperature measurement system provided in this embodiment is used to perform any of the temperature measurement methods in Embodiment 1, and therefore has the same beneficial effects as Embodiment 1.

[0105] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify, alter, or combine the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A temperature measurement method, characterized in that, Includes the following steps: S1: Provides a semiconductor device, a thickness measurement device, a refractive index measurement device, and a theoretical relationship between thickness and temperature. The semiconductor device includes a reaction chamber, a base located within the reaction chamber, and a heating device. The top of the reaction chamber has a gas passage for introducing process gas into the reaction chamber. The base includes a recess, and the inner wall of the recess has a support platform along its circumference for supporting the edge of the workpiece under test, such that there is a gap between the bottom surface of the workpiece under test and the bottom surface of the recess. S2: Place the optically transparent workpiece under test on the base, control the heating device to heat the base, and control the emission bandwidth of the thickness measurement device and the refractive index measurement device to the light-receiving surface of the workpiece under test to not exceed 0.

1. A first light beam (nanometer-sized) and a second light beam (with a bandwidth ratio of not less than 100:1 and the same center wavelength as the first light beam) are emitted to the test piece through the gas passage. The first light beam is a laser, and the second light beam is a beam emitted by a blue LED. The center wavelength range of the first and second light beams is 405 nm ± 5 nm, and the bandwidth of the second light beam is not less than 10 nm. S3: Obtain the real-time refractive index n of the test piece based on the reflected light information of the second light beam through the test piece. Calculate the real-time corrected thickness d of the test piece based on the interference light information of the first light beam through the test piece and the real-time refractive index n. c ; S4: Based on the real-time correction thickness d c Based on the theoretical relationship between the thickness and temperature, the real-time temperature T of the test piece is calculated.

2. The temperature measurement method according to claim 1, characterized in that, The theoretical relationship between thickness and temperature is: d = d0[1 + α(T - T0)], where d is the thickness, d0 is the initial thickness, T is the real-time temperature, T0 is the room temperature, and α is the coefficient of thermal expansion; step S1 further includes providing the coefficient of thermal expansion α of the test piece and the initial thickness d0 at room temperature T0; in step S4, the thickness d is corrected according to the real-time thickness d c The real-time temperature T is calculated from the ambient temperature T0, the corresponding initial thickness d0, and the theoretical relationship between the thickness and temperature.

3. The temperature measurement method according to claim 1, characterized in that, Both the light-receiving and back-light-receiving surfaces of the test piece are polished.

4. The temperature measurement method according to claim 1, characterized in that, The thickness of the test piece does not exceed 10 mm.

5. The temperature measurement method according to claim 1, characterized in that, The first beam is a laser.

6. The temperature measurement method according to claim 1, characterized in that, During step S2, the first beam and the second beam are switched on and off using mechanical chopping or direct electrical modulation, and the refractive index measuring device is controlled to be in the off state while the thickness measuring device emits the first beam.

7. The temperature measurement method according to claim 1, characterized in that, In step S3, the step of obtaining the real-time refractive index n of the test piece includes: obtaining the real-time reflectivity R of the test piece using the reflected light information of the second beam; and obtaining the real-time refractive index n based on the real-time reflectivity R and the correspondence between reflectivity and refractive index.

8. The temperature measurement method according to claim 7, characterized in that, The second light beam exits perpendicularly to the light-receiving surface of the test piece, and the relationship between the reflectivity and refractive index is: R = [(n-1) / (n+1)] 2 .

9. The temperature measurement method according to claim 1, characterized in that, In step S3, the real-time corrected thickness d of the test piece is calculated. c The steps include: obtaining the real-time optical path difference L based on the corresponding interference light information fed back by the first beam; and obtaining the real-time corrected thickness d based on the real-time optical path difference L and the real-time refractive index n. c .

10. The temperature measurement method according to claim 9, characterized in that, The first beam exits perpendicularly to the light-receiving surface of the test piece, and the real-time corrected thickness is calculated using the following formula: d c =L / (2n).

11. The temperature measurement method according to claim 1, characterized in that, The test piece in step S2 is a substrate. After step S4, the following preset process steps are also performed: control the heating device to heat the base until the process isothermal state is reached, and provide process gas to the reaction chamber where the test piece is located, so as to grow an optically transparent homogeneous material layer on the light-receiving surface of the test piece. During the execution of the preset process steps, step S2 controls the thickness measuring device and the refractive index measuring device to emit a first beam with a bandwidth of no more than 0.1 nanometers and a second beam with a bandwidth ratio of no less than 100:1 and the same as the center wavelength of the first beam, respectively, onto the light-receiving surface of the test piece; and step S3 obtains the real-time growth thickness of the homogeneous material layer.

12. A temperature measurement system, characterized in that, For performing the temperature measurement method according to any one of claims 1 to 11, the temperature measurement system includes: a thickness measuring device configured to emit a first light beam with a bandwidth not exceeding 0.1 nanometers, and to receive interference light information fed back from the first light beam; and a refractive index measuring device configured to emit a second light beam with a bandwidth ratio not less than 100:1 to the first light beam and consistent with the center wavelength of the first light beam, and to receive reflected light information fed back from the second light beam.

13. The temperature measurement system according to claim 12, characterized in that, It also includes a main control device that communicates with the thickness measuring device and the refractive index measuring device, so as to obtain the real-time refractive index n of the test piece based on the reflected light information of the second beam, and to calculate the real-time corrected thickness d of the test piece based on the interference light information of the first beam and the real-time refractive index n. c ; The main control device has a pre-stored theoretical correspondence between thickness and temperature, so as to correct the thickness d in real time. c Based on the theoretical relationship between the thickness and temperature, the real-time temperature T of the test piece is calculated.

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