Wafer surface high-precision temperature measurement method and device based on photoluminescence principle

Abstract

The application discloses a wafer surface high-precision temperature measuring method and device based on a photoluminescence principle, wherein a fluorescent or phosphorescent material is coated on a wafer surface; the material emits fluorescent light or phosphorescent light after being excited by an external light source; a temperature sensor arranged at a key point is combined to complete calibration of the coated wafer; high-temporal and spatial resolution temperature response characteristics of the whole wafer surface are calculated; and high-precision, high-temporal and spatial resolution wafer temperature measurement can be realized.

Description

Technical Field

[0001] This invention relates to the field of wafer surface temperature measurement technology, specifically to a high-precision wafer surface temperature measurement method and device based on the photoluminescence principle. Background Technology

[0002] Wafer surface temperature measurement refers to the process of measuring the surface temperature of a semiconductor wafer using specific methods or equipment. With the increasing sophistication of semiconductor processes, temperature control of the wafer surface has become crucial. Temperature affects yield throughout the entire integrated circuit chip production process, including wafer fabrication, etching, and deposition. Inaccurate or uneven temperatures can lead to wafer warping, thermal stress, and even microcracks, severely impacting chip yield and performance. Therefore, high-precision monitoring and control of the temperature field distribution on the wafer surface are essential during the manufacturing process.

[0003] Currently, wafer surface temperature measurement typically employs two methods: contact and non-contact. Contact temperature measurement integrates tiny sensors at specific locations on the wafer surface for temperature monitoring. During wafer fabrication, the sensors measure temperature information at different coordinates, encode this information into digital signals, and write it into a storage circuit. The main control chip then transmits the stored data wirelessly. This method is technologically mature, offers high measurement accuracy, and is low-cost. However, because the sensors can only perform point measurements, their spatial resolution is limited, failing to meet the high-precision temporal and spatial requirements. Non-contact temperature measurement primarily uses radiation thermometry, which does not contact the wafer. By measuring radiated heat, the temperature of the wafer surface is calculated using radiation formulas. Non-contact temperature measurement offers a large measurement range, real-time monitoring, and fast response time. However, because it uses radiated heat measurement, it is susceptible to environmental influences, resulting in low measurement accuracy at low temperatures.

[0004] In summary, new technologies and methods are urgently needed to achieve high-precision, high-spatiotemporal resolution, large-scale wafer surface temperature measurement. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a high-precision temperature measurement method and device for wafer surfaces based on the principle of photoluminescence.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a high-precision temperature measurement method for wafer surfaces based on the photoluminescence principle, comprising the following steps:

[0008] S1. Arrange temperature sensors at designated points on the surface of a wafer coated with fluorescent or phosphorescent materials.

[0009] S2. Perform the following wafer surface temperature measurement process at different standard temperature points:

[0010] The tunable laser source emits excitation light of a specific wavelength, the excitation light is reflected to the surface of the wafer through the reflecting lens, the surface of the wafer coated with fluorescent or phosphorescent material is excited by the excitation light to generate light signals of a specific wavelength;

[0011] The convex lens converges the light signals emitted from the surface of the wafer; the light signals converged through the convex lens further pass through the filter group, the filter group filters out the noise components in the light signals, and only retains the light signals generated by the fluorescent or phosphorescent material; the pure light signals obtained after filtering through the filter group finally reach the detector, the detector converts the captured pure light signals into corresponding electrical signals, and transmits the electrical signals to the computer;

[0012] S3, each temperature sensor simultaneously transmits the temperature value obtained at the point to the computer;

[0013] S4, through steps S2 and S3, the computer obtains the corresponding relationship between the electrical signals at different standard temperature points and the temperature data measured by the temperature sensor, and further fits the equation through a mathematical algorithm, so as to obtain the quantitative relationship between the electrical signals and the temperature;

[0014] S5, when actual temperature measurement is performed, the wafer surface to be measured is coated with fluorescent or phosphorescent material calibrated, and then the wafer surface temperature measurement process is performed according to step S2, and the computer uses the equation fitted through the mathematical algorithm in step S4 to calculate the temperature data of the wafer surface according to the received electrical signals.

[0015] Further, the time controller coordinates the working time of the tunable laser source and the signal acquisition time of the detector through the time control mechanism, controls the tunable laser source to emit stable excitation light within the set time interval, and controls the detector to be able to perform signal acquisition within the set optimal time window.

[0016] The application also provides a wafer surface high-precision temperature measurement device for realizing the above method, comprising a detector, a computer, a filter group, a convex lens, a tunable laser source, a reflecting lens, fluorescent or phosphorescent material, a wafer and a temperature sensor.

[0017] The tunable laser source is used for emitting excitation light of a specific wavelength, the reflecting lens is used for receiving the excitation light and reflecting the excitation light to the surface of the wafer; the surface of the wafer is coated with a fluorescent or phosphorescent material; the convex lens is used for receiving the light signal emitted from the surface of the wafer and performing converging processing on the light signal; the filter set is used for filtering the light signal after converging by the convex lens, filtering out the noise component in the light signal, and only retaining the light signal generated by the fluorescent or phosphorescent material; the detector is used for receiving the pure light signal filtered by the filter set and converting the pure light signal into an electric signal, and transmitting the electric signal to the computer;

[0018] The temperature sensor comprises a plurality of temperature sensors, and each temperature sensor is arranged at a preset point on the surface of the wafer during calibration, and is used for obtaining the temperature value of the point at a current standard temperature point and transmitting the temperature value to the computer;

[0019] The computer is used for fitting an equation by a mathematical algorithm according to the corresponding relationship between the electric signal and the temperature data measured by the temperature sensor at different standard temperature points during calibration, and obtaining the quantitative relationship between the electric signal and the temperature; and the computer is used for calculating the temperature data of the surface of the wafer according to the received electric signal by using the equation fitted by the mathematical algorithm during actual temperature measurement.

[0020] Further, the device further comprises a timing controller, which is respectively connected to the tunable laser source and the detector in communication, and is used for coordinating the working time of the tunable laser source and the signal acquisition time of the detector, controlling the tunable laser source to emit stable excitation light within a set time interval, and controlling the detector to perform signal acquisition within a set optimal time window.

[0021] The present application has the following advantages:

[0022] 1. The present application realizes high-precision temperature measurement of the surface of the wafer by calibrating the temperature response characteristic equation based on the temperature-sensitive characteristics of the fluorescent or phosphorescent material, is suitable for measuring a wide range of temperature changes, solves the problems of weak signal and poor measurement precision of the traditional thermometer in a low-temperature environment, and ensures the accuracy of the measured temperature data of the surface of the wafer.

[0023] 2. The present application realizes high-temporal and high-spatial resolution temperature measurement by combining in-situ calibration with photoluminescence temperature measurement, is suitable for high-precision measurement under the demand of planar high-resolution, solves the problem of discontinuous spatial measurement of the traditional thermometer, and provides important support for integrated circuit surface temperature source monitoring. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 A device used to realize the method of embodiment 1 of the present application is shown in the schematic diagram.

[0025] Fig. 2 Schematic diagram of the position of the wafer surface temperature sensor when calibrating in embodiment 1 of the present application;

[0026] The figure shows: 1, a detector; 2, a timing controller; 3, a computer; 4, a filter set; 5, a convex lens sheet; 6, a tunable laser source; 7, a mirror sheet; 8, a fluorescent or phosphorescent material; 9, a wafer; 10, an experimental table; 11, a temperature sensor. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings. It should be noted that the present embodiment is based on the technical solution, and gives a detailed implementation and specific operation process, but the protection scope of the present application is not limited to the present embodiment. Embodiment 1

[0028] The present embodiment provides a wafer surface high-precision temperature measurement method based on the photoluminescence principle, as shown in the figure, comprising the following steps: Figs. 1-2

[0029] S1, arranging temperature sensors 11 (the number of arrangement in the present embodiment is 5) on the set point positions on the surface of the wafer 9 coated with the fluorescent or phosphorescent material 8;

[0030] S2, respectively executing the following wafer surface temperature measurement process at different standard temperature points:

[0031] The tunable laser source 6 emits excitation light of a specific wavelength, the excitation light is reflected to the surface of the wafer 9 by the mirror sheet 7, and the fluorescent or phosphorescent material 8 coated on the surface of the wafer 9 is excited by the excitation light to generate a light signal of a specific wavelength. It should be noted that the wavelength, intensity and lifetime of the light signal emitted by the fluorescent or phosphorescent material 8 are determined by the characteristics of the fluorescent or phosphorescent material 8, and are the result of the interaction between the fluorescent or phosphorescent material 8 and the excitation light.

[0032] The convex lens sheet 5 converges the light signal emitted from the surface of the wafer 9, focusing the dispersed light signal into a light signal with concentrated intensity, facilitating subsequent signal acquisition and processing. The light signal after converging by the convex lens sheet 5 is further passed through the filter set 4, which filters out the reflected light from the excitation light, the environmental background light and other possible noise components of the interference signal in the light signal, and only retains the light signal generated by the fluorescent or phosphorescent material 8. This process can ensure the purity of the light signal and the accuracy of the detection. The pure light signal obtained after filtering by the filter set 4 finally reaches the detector 1, which converts the captured pure light signal into a corresponding electrical signal and transmits the electrical signal to the computer 3;

[0033] ​S3, each temperature sensor 11 simultaneously transmits the temperature value of the point at the current standard temperature point to the computer 3;

[0034] S4, through steps S2 and S3, the computer 3 can obtain the corresponding relationship between the electrical signal and the temperature value measured by the temperature sensor at different standard temperature points, and the accurate quantitative relationship between the electrical signal and the temperature can be obtained by fitting the equation through a mathematical algorithm;

[0035] S5, when actual temperature measurement is performed, the wafer surface to be measured is coated with a calibrated fluorescent or phosphorescent material 8, and then the wafer surface temperature measurement process is performed according to step S2, and the computer 3 calculates the temperature data of the wafer surface according to the received electrical signal by using the equation fitted through the mathematical algorithm in step S4.

[0036] In the embodiment, the time controller 2 coordinates the working time of the tunable laser source 6 and the signal acquisition time of the detector 1 with a high-precision time control mechanism, and controls the tunable laser source 6 to emit stable excitation light within a set time interval and controls the detector 1 to perform signal acquisition within a set optimal time window through precise time matching, so as to avoid omission or time misalignment of the signal.

[0037] It should be noted that since the characteristic emission spectrum of the fluorescent or phosphorescent material is usually distributed in a narrow band, and the stray light of the excitation light source (such as an ultraviolet LED or a laser), the environmental background radiation (such as infrared thermal radiation or visible light interference), and the dark current noise of the photodetector often cover a wider band, therefore, the embodiment accurately matches the target wavelength window through a high-performance band-pass filter, and only retains the light signal generated by the fluorescent or phosphorescent material.

[0038] It should be noted that when the fluorescent or phosphorescent material is excited, four stages appear, namely, an excited period, a completely excited period, a decay period, and an unexcited period. When temperature detection is performed based on the lifetime principle, the time window should include part of the completely excited period and the entire decay period; when temperature detection is performed based on the intensity ratio, the time window should only include part or the entire completely excited period. Embodiment 2

[0039] The embodiment provides a wafer surface high-precision temperature measurement device for implementing the method in embodiment 1, which comprises a detector 1, a computer 3, a filter set 4, a convex lens 5, a tunable laser source 6, a mirror 7, a fluorescent or phosphorescent material 8, a wafer 9, and a temperature sensor 11.

[0040] The tunable laser source 6 is used to emit excitation light of a specific wavelength, the reflecting lens 7 is used to receive the excitation light and reflect the excitation light to the surface of the wafer 9; the surface of the wafer 9 is coated with a fluorescent or phosphorescent material 8; the convex lens 5 is used to receive the light signal emitted from the surface of the wafer 9 and perform converging processing on the light signal; the filter set 4 is used to filter the light signal after converging by the convex lens 5, filter out the noise component in the light signal, and only keep the light signal generated by the fluorescent or phosphorescent material; the detector 1 is used to receive the pure light signal filtered by the filter set 4 and convert the pure light signal into an electric signal, and transmit the electric signal to the computer 3;

[0041] The temperature sensor 11 includes a plurality of temperature sensors, and each temperature sensor 11 is arranged at a set point on the surface of the wafer 9 during calibration, and is used to obtain the temperature value of the point at the current standard temperature point and transmit the temperature value to the computer 3;

[0042] The computer 3 is used to obtain the quantitative relationship between the electric signal and the temperature by fitting an equation through a mathematical algorithm according to the corresponding relationship between the electric signal and the temperature data measured by the temperature sensor at different standard temperature points during calibration; and is used to calculate the temperature data of the surface of the wafer according to the received electric signal by using the equation fitted through the mathematical algorithm during actual temperature measurement.

[0043] In the embodiment, the wafer 9 is placed on the experimental table 10.

[0044] In the embodiment, the device further includes a timing controller 2, which is respectively communicatively connected to the tunable laser source 6 and the detector 1, and is used to coordinate the working time of the tunable laser source 6 and the signal acquisition time of the detector 1, control the tunable laser source 6 to emit stable excitation light within a set time interval, and control the detector 1 to perform signal acquisition within a set optimal time window.

[0045] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all these changes and modifications should be included in the protection scope of the claims of the present application.

Claims

1. A high-precision temperature measurement method for wafer surfaces based on the photoluminescence principle, characterized in that, Includes the following steps: S1. Temperature sensors (11) are arranged at designated points on the surface of a wafer (9) coated with fluorescent or phosphorescent material (8), and the temperature sensors (11) include multiple sensors. S2. Perform the following wafer surface temperature measurement process at different standard temperature points: A tunable laser source (6) emits excitation light of a specific wavelength. The excitation light is reflected by a reflective lens (7) onto the surface of a wafer (9). The fluorescent or phosphorescent material (8) coated on the surface of the wafer (9) is excited by the excitation light to generate a light signal of a specific wavelength. The convex lens (5) converges the light signal emitted from the surface of the wafer (9); the light signal converged by the convex lens (5) further passes through the filter group (4), the filter group (4) filters out the noise components in the light signal, and only retains the light signal generated by the fluorescent or phosphorescent material (8); the pure light signal obtained after being filtered by the filter group (4) finally reaches the detector (1), the detector (1) converts the captured pure light signal into the corresponding electrical signal, and transmits the electrical signal to the computer (3); the timing controller (2) coordinates the working time of the tunable laser source (6) and the signal acquisition time of the detector (1) through the time control mechanism, controls the tunable laser source (6) to emit stable excitation light within the set time interval, and controls the detector (1) to be able to acquire signals within the set optimal time window; S3. Each temperature sensor (11) simultaneously transmits the temperature value obtained at its location to the computer (3); S4. Through steps S2 and S3, the computer (3) obtains the correspondence between the electrical signal and the temperature data measured by the temperature sensor at different standard temperature points. Further, by fitting the equation through a mathematical algorithm, the quantitative relationship between the electrical signal and the temperature can be obtained. S5. When performing actual temperature measurement, a calibrated fluorescent or phosphorescent material (8) is coated on the surface of the wafer to be measured. Then, the wafer surface temperature measurement process is performed according to step S2. The computer (3) uses the equation obtained by fitting the mathematical algorithm in step S4 to calculate the temperature data of the wafer surface based on the received electrical signal.

2. A high-precision temperature measurement device for a wafer surface implementing the method of claim 1, characterized in that, It includes a detector (1), a computer (3), a filter group (4), a convex lens (5), a tunable laser source (6), a reflective mirror (7), a fluorescent or phosphorescent material (8), a wafer (9), and a temperature sensor (11); The tunable laser source (6) is used to emit excitation light of a specific wavelength, and the reflective lens (7) is used to receive the excitation light and reflect it to the surface of the wafer (9). The surface of the wafer (9) is coated with fluorescent or phosphorescent material (8). The convex lens (5) is used to receive the light signal emitted from the surface of the wafer (9) and converge the light signal. The filter group (4) is used to filter the light signal converged by the convex lens (5), filter out the noise components in the light signal, and retain only the light signal generated by the fluorescent or phosphorescent material (8). The detector (1) is used to receive the pure light signal filtered by the filter group (4), convert the pure light signal into an electrical signal, and transmit the electrical signal to the computer (3). The temperature sensor (11) includes multiple sensors. During calibration, each temperature sensor (11) is placed at a set point on the surface of the wafer (9) to obtain the temperature value of the point at the current standard temperature point and transmit it to the computer (3). The computer (3) is used to obtain the quantitative relationship between the electrical signal and the temperature by fitting an equation through a mathematical algorithm during calibration, based on the correspondence between the electrical signal at different standard temperature points and the temperature data measured by the temperature sensor. It is used in actual temperature measurement to fit the equation obtained by mathematical algorithm and to deduce the temperature data of the wafer surface based on the received electrical signal; It also includes a timing controller (2), which is communicatively connected to the tunable laser source (6) and the detector (1) respectively, and is used to coordinate the working time of the tunable laser source (6) and the signal acquisition time of the detector (1), control the tunable laser source (6) to emit stable excitation light within a set time interval, and control the detector (1) to acquire signals within a set optimal time window.

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