Method for calibrating aluminum oxide film of spectrum ellipsometer

Abstract

The invention discloses a method for calibrating an aluminum oxide film of a spectrum ellipsometer. The method comprises the following steps: selecting a SiO thin film which takes silicon as a substrate and has the thickness of 1-3nm as a film thickness standard sample wafer, continuously measuring the standard sample wafer through a spectrum ellipsometer, and calculating the difference between a measured value and a known film thickness value so as to determine the calibration precision. And if the measurement error exceeds + / -0.15 nm, adjusting the intensity of the light source and the parameters of the detector until the measurement result meets the requirement. In the calibration process, the environment temperature is controlled to be 25 + / -2 DEG C, the relative humidity is controlled to be 40%-60%, and the light source stability is kept within + / -0.1%. The method also comprises regular re-calibration so as to maintain long-term measurement precision and ensure consistency of measurement results among different machines. The method is suitable for high-precision film measurement in semiconductor manufacturing and optical element production.

Description

Technical Field

[0001] The invention relates to the technical field of spectrum measurement and calibration, and in particular to an aluminum oxide film calibration method for a spectrum ellipsometer. Background Art

[0002] Spectroscopic ellipsometer is a precision instrument widely used in measuring film thickness and optical constants (such as refractive index and extinction coefficient). Its main working principle is to determine the physical properties of the film by analyzing the changes in polarized light after reflection on the film surface. Due to its non-contact and non-destructive measurement characteristics, spectroscopic ellipsometer plays an important role in semiconductor manufacturing, optical device preparation, and material science.

[0003] Atomic layer deposition (ALD) is a high-precision technology that achieves atomic-level thin film deposition through the alternating adsorption reaction of gas-phase precursors. ALD technology has become one of the key processes for manufacturing nanostructures and functional films due to its excellent three-dimensional coverage, uniform deposition effect and precise sub-nanometer film thickness control. However, the film thickness measurement in the ALD process usually relies on the accuracy and stability of the spectroscopic ellipsometer.

[0004] In actual production, due to different manufacturers, models or calibration methods of spectroscopic ellipsometers, the measurement results of different machines under the same ALD process conditions may differ significantly. These differences usually come from the following aspects:

[0005] Differences in machine control parameters: Key parameters such as light source intensity, spectral range, and detector sensitivity of different machines may differ, resulting in inconsistent film thickness measured under the same conditions.

[0006] Influence of environmental factors: External environmental factors such as temperature, humidity and vibration have an important influence on the stability of measurement results. Especially in high-precision measurements, these factors may introduce small but significant errors.

[0007] Different calibration methods: Different calibration methods are used for different machines when they leave the factory or during use, which leads to deviations in the calibration standards and affects the measurement consistency between different machines.

[0008] These differences not only affect the process control and quality assurance of the ALD process, but also pose challenges to the consistency and repeatability in mass production. Therefore, in the application of spectroscopic ellipsometers, an effective calibration method is urgently needed to unify the measurement standards between different machines and reduce the measurement errors caused by machine differences. Summary of the invention

[0009] The purpose of the present invention is to provide a method for calibrating aluminum oxide thin films for spectroscopic ellipsometer, which has the advantages of improving the measurement consistency of the machine and reducing the measurement error, and solves the problem of ALD thin film measurement differences between different machines.

[0010] To achieve the above object, the present invention provides the following technical solution: a method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer, comprising the following steps:

[0011] S1: Select a film thickness standard sample, the sample includes a SiO2 film with a thickness of 1-3 nm and a silicon substrate, and ensure that the refractive index of the film is 1.457;

[0012] S2: placing the film thickness standard sample at the center of the sample stage of the spectroscopic ellipsometer, and operating the spectroscopic ellipsometer to continuously measure the standard sample, with the number of measurements being no less than 5 times;

[0013] S3: Calculate the average value of the measurement results and compare it with the known film thickness value of the film thickness standard sample to determine whether the measurement result is within the error range of ±0.15nm;

[0014] S4: If the measurement result exceeds the error range of ±0.15nm, adjust the light source intensity and detector setting parameters of the spectroscopic ellipsometer and re-measure until the measurement result meets the requirements;

[0015] S5: Use a calibrated spectroscopic ellipsometer to measure the thickness of actual aluminum oxide film samples to ensure consistent measurement results between different machines and minimize errors.

[0016] Preferably, the substrate material of the film thickness standard sample is silicon, the film material is silicon dioxide, and the film thickness is 1-3 nm. Calculating the error between the standard film thickness value and the actual measurement result includes the following calculation steps:

[0017] Step 1:

[0018] Calculate the average: in is the average of the measured values, X i is the i-th measurement value, n is the number of measurements;

[0019] Step 2:

[0020] Calculation error: Among them, E measuremen t is the measurement error, Y std It is the standard film thickness value.

[0021] Preferably, in step S2, the measurement result of the standard sample is within the error range of ±0.15nm; the error range is determined as follows: if E measuremen t >0.15nm, the machine parameters need to be adjusted.

[0022] Preferably, the measurement error is corrected by adjusting the light source intensity and the detector settings in step S4. The adjusted machine parameters are based on the following algorithm:

[0023] P adjusted =P current +ΔP, where P adjusted is the adjusted machine parameter, P current is the current machine parameter, and ΔP is the adjustment amount.

[0024] Preferably, when calibrating the spectroscopic ellipsometer, the film thickness standard sample is placed in a clean room to reduce the influence of environmental factors on the measurement results; the error evaluation results of the re-measurement include:

[0025] Remeasure and reassess:

[0026] in is the average value after calibration, E final is the final measurement error;

[0027] Calculate the consistency index:

[0028] Where m is the number of machines, E final ,j is the measurement error of different machines;

[0029] Calculate the comprehensive calibration index:

[0030] I calibration =α·E final +β·C consistency , where α and β are weight coefficients used to balance the importance of error and consistency.

[0031] Preferably, the film thickness standard sample is used for calibration of multiple spectroscopic ellipsometers to ensure that the measurement results of all machines are consistent. During the calibration process, the ambient temperature is controlled at 25±2° C. and the relative humidity is controlled between 40% and 60%.

[0032] Preferably, in the step S3, the calibration accuracy of the spectroscopic ellipsometer is determined by calculating the average value of the measured values ​​and comparing them with the known values ​​of the standard film. During the measurement process, the stability of the light source is controlled within ±0.1% to ensure the accuracy of the measurement results.

[0033] Preferably, the calibration process includes regularly recalibrating the spectroscopic ellipsometer to maintain its measurement accuracy.

[0034] Preferably, after the calibration is completed, the thickness of the aluminum oxide film is measured using a calibrated spectroscopic ellipsometer to ensure the accuracy of all subsequent measurements.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention achieves the effect of unifying the ALD process measurement results between different spectral ellipsometers by setting a silicon substrate SiO2 thin film standard as a calibration reference, thereby significantly reducing the measurement error between the machines.

[0037] 2. The present invention improves the repeatability and reliability of the calibration process by introducing environmental control parameters, such as temperature and humidity stability control, during the calibration process, thereby ensuring that the measurement results of the spectroscopic ellipsometer are consistent under different environmental conditions.

[0038] 3. The present invention effectively solves the measurement deviation problem caused by equipment aging or environmental changes by regular recalibration and automatic adjustment of light source intensity, thereby ensuring the measurement accuracy of the spectroscopic ellipsometer in long-term use.

[0039] 4. The present invention reduces the accidental errors that may occur in a single measurement by adopting a method of multiple measurements and taking an average value, thereby further improving the accuracy and reliability of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of the steps of the aluminum oxide film calibration method for a spectroscopic ellipsometer of the present invention;

[0041] Figure 2 The present invention is a flow chart of the measurement error calculation of the aluminum oxide film calibration method of the spectroscopic ellipsometer;

[0042] Figure 3 The error range determination flow chart of the aluminum oxide film calibration method of the spectroscopic ellipsometer of the present invention;

[0043] Figure 4 The parameter adjustment calculation flow chart of the aluminum oxide film calibration method of the spectroscopic ellipsometer of the present invention;

[0044] Figure 5 The error evaluation and consistency calculation flow chart of the aluminum oxide film calibration method of the spectroscopic ellipsometer of the present invention;

[0045] Figure 6 It is a flow chart of environmental condition control in the calibration of the spectroscopic ellipsometer of the present invention;

[0046] Figure 7This is a flow chart of the measurement accuracy and light source stability control of the spectroscopic ellipsometer of the present invention;

[0047] Figure 8 The following is a flow chart of the periodic recalibration of the spectroscopic ellipsometer of the present invention;

[0048] Fig. 9 The present invention is a flow chart of measuring the thickness of aluminum oxide film by using a calibrated spectroscopic ellipsometer. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] See also Figures 1 to 9 The present invention provides a method for calibrating aluminum oxide thin films using a spectroscopic ellipsometer, which aims to improve the measurement consistency between different spectroscopic ellipsometers and reduce the measurement errors caused by machine differences. The method ensures the high accuracy and stability of the spectroscopic ellipsometer when measuring the thickness of aluminum oxide thin films through a series of calibration steps.

[0051] S1: Select the standard film thickness sample

[0052] In the first step of the present invention, a film thickness standard sample is selected, which has a SiO2 film with a silicon substrate. The thickness of the film ranges from 1 to 3 nm, and the refractive index is set to 1.457. This selection is based on the consideration of the optical properties and measurement accuracy requirements of the spectroscopic ellipsometer. The SiO2 film on the silicon substrate is an ideal material for the calibration process due to its stable physical properties and precise thickness control capabilities.

[0053] The thickness of the SiO2 film is in the range of 1-3nm, and is strictly controlled by the manufacturing process to ensure that its refractive index is 1.457. This refractive index is chosen to match the measurement spectral range of the spectroscopic ellipsometer, so that the spectroscopic ellipsometer can obtain accurate reflection data during calibration.

[0054] S2: Place the film thickness standard sample at the center of the sample stage of the spectroscopic ellipsometer, and operate the spectroscopic ellipsometer to continuously measure the standard sample.

[0055] In the second step, the selected film thickness standard is placed at the center of the sample stage of the spectroscopic ellipsometer. This position is chosen to ensure that the measurement beam can be evenly illuminated on the sample surface, so as to obtain reliable measurement data.

[0056] Operate the spectroscopic ellipsometer to continuously measure the standard sample for no less than 5 times. The purpose of continuous measurement is to reduce the accidental error in a single measurement and ensure the stability and repeatability of the measurement results. Through multiple measurements, a more reliable average value can be calculated, which is crucial for subsequent calibration work.

[0057] S3: Calculate the average value of the measurement results and compare it with the known film thickness value of the film thickness standard sample to determine whether the measurement result is within the error range of ±0.15nm

[0058] In the third step, the average value of the data obtained from the continuous measurements is calculated. This average value represents the measurement results of the spectroscopic ellipsometer under the current calibration conditions. This average value is compared with the known film thickness value of the film thickness standard sample to determine the measurement error of the spectroscopic ellipsometer.

[0059] The error tolerance set in the present invention is ±0.15 nm, which is determined based on the measurement accuracy requirements of the spectroscopic ellipsometer. If the measurement result is within this error range, it means that the measurement accuracy of the spectroscopic ellipsometer meets the requirements, and the next step of operation can be continued.

[0060] S4: If the measurement result exceeds the error range of ±0.15nm, adjust the light source intensity and detector setting parameters of the spectroscopic ellipsometer and re-measure.

[0061] In the fourth step, if the measurement result is outside the set error range, the key parameters of the spectroscopic ellipsometer need to be adjusted. These parameters include the light source intensity and the detector settings. The purpose of these adjustments is to eliminate possible systematic errors and make the spectroscopic ellipsometer measurements more accurate.

[0062] After adjustment, the measurement is repeated and the average is calculated again until the measurement result falls within the error range of ±0.15nm. This process ensures that the spectroscopic ellipsometer is properly calibrated and can perform accurate film thickness measurements.

[0063] S5: Thickness measurement of actual aluminum oxide thin film samples using a calibrated spectroscopic ellipsometer

[0064] After the calibration is completed, the calibrated spectroscopic ellipsometer is used to measure the thickness of the actual aluminum oxide film sample. The purpose of this step is to verify the validity of the calibration and ensure that the measurement results of the actual sample meet the expected accuracy requirements.

[0065] In order to further reduce the measurement errors between different machines, the present invention uses the same film thickness standard sample and operates under the same conditions when calibrating multiple spectroscopic ellipsometers. This method can effectively reduce the measurement deviation between machines, ensure the consistency of measurement results of different machines, and thus improve the reliability and consistency of measurement in mass production.

[0066] Furthermore, the substrate material of the film thickness standard sample is silicon, the film material is silicon dioxide, and the film thickness is 1-3nm. Calculating the error between the standard film thickness value and the actual measurement result includes the following calculation steps:

[0067] Step 1:

[0068] Calculate the average: in is the average of the measured values, X i is the i-th measurement value, n is the number of measurements;

[0069] Step 2:

[0070] Calculation error: Among them, E measuremen t is the measurement error, Y std It is the standard film thickness value.

[0071] A calculation step for a spectroscopic ellipsometer aluminum oxide film calibration method, in particular, calculating the error between the thickness of the film thickness standard sample and the actual measurement result. This calculation step involves two key formulas, which are used to calculate the average value of the measured value and the measurement error, respectively. Step 1: Calculate the average value: In this step, we first need to calculate the average value of the measured value, expressed as The formula is as follows: in: is the average value of the measured values, which is the sum of all the measurement results divided by the number of measurements n; X i is the specific value of the ith measurement, which is obtained from the actual measurement of the standard sample by the spectroscopic ellipsometer. These values ​​reflect the perception of the thickness of the sample by the spectroscopic ellipsometer under the current settings and environmental conditions; n is the number of measurements. In actual operation, the selection of no less than 5 measurements is based on statistical principles. Increasing the number of measurements can reduce the impact of accidental errors on the final result and improve the reliability of the result. Usually, 5 measurements are enough to provide a stable average value, but under high precision requirements, the number of measurements may be more.

[0072] Step 2: Calculate the error

[0073] After calculating the average value of the measurements, the next step is to calculate the error between the average value and the known film thickness value of the standard sample. The formula is as follows: Where: E measuremen t is the measurement error, which indicates the difference between the measurement result and the standard value. is the average value of the measurements calculated from step 1.

[0074] Y std It is the known film thickness value of the standard sample. This value is usually obtained by a highly accurate reference method or by a known precision manufacturing process. The standard film thickness value is usually provided by the manufacturer, and its accuracy is ensured based on the precision manufacturing process. In the present invention, the standard film thickness value of SiO2 film is set to 1-3nm and has been verified by a reliable reference standard. This value is the reference point in the calibration process and is used to evaluate the measurement accuracy of the spectroscopic ellipsometer.

[0075] Error E measuremen t :The measurement error reflects the gap between the actual operation of the spectroscopic ellipsometer and the theoretical standard. The size of the error can be directly used to evaluate whether the device needs further calibration or adjustment. For example, in the implementation of the present invention, if the error exceeds the allowable range of ±0.15nm, the spectroscopic ellipsometer needs to be further adjusted;

[0076] Through the above steps, the present invention can accurately evaluate the measurement results of the spectroscopic ellipsometer and promptly discover and correct possible measurement errors. These calculation processes are the core of the calibration method, ensuring that the device can provide consistent and accurate measurement results under different operating conditions.

[0077] In the present invention, the error range is set to ±0.15nm. This range is determined based on the measurement accuracy requirements of the spectroscopic ellipsometer and the common error standards in practical applications. For the measurement of nano-scale films, such an error range can ensure stable and reliable measurement data in actual production and quality control processes;

[0078] Calculation and judgment of error: In step S2, the average value of the measurement results is calculated through multiple measurements. Then, compare this average value with the known film thickness value Y of the standard sample. std Compare and calculate the measurement error E measuremen t : If the calculated measurement error E measuremen t If the error is within the range of ±0.15nm, it means that the measurement accuracy of the spectroscopic ellipsometer meets the expectations and no further adjustment is required. However, if the error exceeds the range of ±0.15nm, it means that the current state of the device cannot meet the measurement accuracy requirements and the device needs to be adjusted.

[0079] Necessity of equipment parameter adjustment

[0080] Adjustment conditions:

[0081] When the measurement error E measuremen t >0.15nm, the system will automatically determine that the device needs to be adjusted. Device adjustment usually involves the following aspects:

[0082] Light source intensity adjustment: Changes in light source intensity may affect the reflection and transmission characteristics of the measurement light, thereby affecting the measurement results. Therefore, adjusting the light source intensity can help restore the accuracy of the measurement.

[0083] Detector sensitivity adjustment: The detector setting parameters will also affect the reception and processing of signals. If the detector sensitivity is too high or too low, it will cause measurement errors. By properly adjusting the detector sensitivity, the systematic error in the measurement process can be reduced.

[0084] Adjusted measurements:

[0085] After making necessary adjustments to the equipment parameters, the spectroscopic ellipsometer will re-measure the standard sample and repeat the above steps until the measurement error returns to within the range of ±0.15nm. This process ensures the accuracy of the final measurement results and the stability of the equipment.

[0086] By setting strict error range judgment criteria, the present invention can ensure high-precision operation of the spectroscopic ellipsometer during the calibration process. Even if the measurement error exceeds the allowable range, the adjustment step of the equipment parameters provides an effective solution, thereby ensuring the measurement consistency and reliability between different spectroscopic ellipsometers. This method has broad application prospects in high-precision measurement, especially in the fields of semiconductor manufacturing and materials science.

[0087] During the calibration of the spectroscopic ellipsometer, if the measurement error exceeds the preset allowable range (e.g. ±0.15nm), the device needs to be adjusted. These adjustments are mainly for light source intensity and detector sensitivity, with the aim of reducing system errors by optimizing these key parameters and returning the measurement results to the accurate range.

[0088] Calculation of machine parameters after adjustment:

[0089] Adjusted machine parameters P adjusted The calculation formula is as follows: adjusted =P current +ΔP, where: P adjusted Indicates the adjusted machine parameters. This parameter is the set value used for subsequent measurements after the equipment has been adjusted.

[0090] P current The current machine parameters are the parameter settings used by the device before adjustment. These parameters reflect the state of the device under the current conditions; the current machine parameters usually include settings such as the light source intensity and detector sensitivity of the spectroscopic ellipsometer. In practical applications, these parameters are determined by the initial settings of the device or the previous calibration process. They directly affect the reflection and reception of the measurement light, thereby affecting the accuracy of the measurement results;

[0091] ΔP is the adjustment value, which means the value that needs to be increased or decreased based on the current parameters to achieve the purpose of correcting the measurement error. The adjustment value ΔP is calculated by analyzing the measurement error E. measuremen t If the measurement error is large, the adjustment amount may be large; if the measurement error is small, the adjustment amount may be relatively small. The selection of the adjustment amount needs to consider the response characteristics of the equipment to ensure that the adjusted parameters can effectively correct the error without introducing new errors.

[0092] Practical operations during adjustment

[0093] During the adjustment process, the operator or the automated system will adjust the light source intensity or detector sensitivity of the spectroscopic ellipsometer accordingly based on the calculated adjustment amount ΔP. After the adjustment is completed, the device will re-measure and calculate the new measurement error E measuremen t , and determine whether further adjustments are needed.

[0094] If the adjusted measurement result meets the preset error range (e.g. ±0.15nm), the calibration process can be ended and the device can continue to be used for actual measurement. If the measurement result still does not meet the requirements, the adjustment steps need to be repeated until the measurement error meets the standard.

[0095] Measurement and error evaluation after calibration

[0096] Remeasure and reassess:

[0097] After adjusting the equipment parameters, the standard sample needs to be measured again to verify the effect of the adjustment. The average value after calibration;

[0098] and the final measurement error E final The calculation formula is as follows:

[0099]

[0100]

[0101] in: is the average measurement value after calibration, which represents the average result after multiple measurements of the standard sample. Similar to the previous measurement steps, by calculating the average value, the influence of accidental errors can be reduced and the reliability of the measurement results can be improved.

[0102] E final is the final measurement error, which indicates the difference between the measured result after calibration and the known film thickness value Y of the standard sample. std By calculating this error, it can be determined whether the calibration has achieved the expected effect.

[0103] Calculation of consistency index

[0104] Consistency Index C consistency Calculation:

[0105] In order to ensure the measurement consistency between different machines, the present invention introduces the consistency index C consistency , which is used to evaluate the deviation of measurement results of different machines. Its calculation formula is as follows:

[0106] Where: m is the number of machines, indicating the total number of spectroscopic ellipsometer machines involved in the measurement.

[0107] E final is the final measurement error of the jth machine.

[0108] Consistency Index C consistency Indicates the average value of the measurement error between different machines. If the index is small, it means that the measurement results between the machines are highly consistent; conversely, if the index is large, it means that there are large measurement differences between different machines, and further calibration or adjustment is required.

[0109] Calculation of comprehensive calibration indicators

[0110] Comprehensive calibration index I calibration Calculation: In order to comprehensively evaluate the calibration effect, the present invention also introduces a comprehensive calibration index I calibration , and its calculation formula is as follows:

[0111] I calibration =α·E final +β·C consistency , where and are weight coefficients used to balance the final error E final and consistency index C consistency The importance of.

[0112] I calibration It is a comprehensive calibration indicator that reflects the overall effect after calibration. By adjusting the weight coefficients α and β, different priorities can be given to the final error or consistency indicators according to different application requirements.

[0113] Choice of weight coefficients α and β:

[0114] If more attention is paid to the measurement accuracy of a single machine, the value of α can be increased, so that the final error E final The impact on the comprehensive calibration indicators is greater.

[0115] If more attention is paid to the measurement consistency between different machines, the value of β can be increased, so that the consistency index C consistency The impact on the comprehensive calibration indicators is greater.

[0116] In order to ensure that the calibration process of the spectroscopic ellipsometer has high repeatability and reliability, the present invention particularly stipulates the control range of the ambient temperature and relative humidity during the calibration process. Specifically, the ambient temperature should be controlled at 25±2°C, and the relative humidity should be controlled between 40% and 60%.

[0117] Importance of temperature control: Temperature has a direct impact on the optical components, detector sensitivity, and light source output of the spectroscopic ellipsometer. Too high or too low a temperature may cause changes in the physical properties of the components inside the spectroscopic ellipsometer, thus affecting the measurement results. Therefore, controlling the temperature within the range of 25±2℃ helps reduce the measurement error caused by temperature fluctuations and ensures the consistency of the measurement results.

[0118] Importance of humidity control: Relative humidity also has a significant impact on the stability of the optical components and circuits inside the device. Too high humidity may cause condensation on the surface of the optical components, thereby affecting the transmission or reflection characteristics of light; too low humidity may cause static electricity accumulation, affecting the stability of the measurement signal. Therefore, controlling the humidity between 40% and 60% can effectively reduce the impact of ambient humidity on the measurement results.

[0119] By strictly controlling the environmental conditions, the present invention can ensure that calibration operations performed on different machines have the same basic environmental conditions, so that the measurement results between multiple machines remain consistent.

[0120] The present invention stipulates that in step S3, the light source stability of the spectroscopic ellipsometer must be controlled within ±0.1%, in order to ensure that the fluctuation of the light source intensity during the measurement process will not have a significant impact on the measurement result.

[0121] The influence of light source stability on measurement: Spectroscopic ellipsometer measures the thickness of the film by illuminating the sample with a light source and analyzing the changes in reflected light or transmitted light. If the light source intensity is unstable, the intensity of the reflected light or transmitted light will also fluctuate, resulting in an unstable measurement signal, thus affecting the final measurement result. Controlling the light source stability within ±0.1% can ensure that the influence of light source intensity fluctuations on the measurement results is minimized.

[0122] Light source calibration: To achieve this goal, the light source of the spectroscopic ellipsometer can be preheated before calibration to reach a stable state; the stability of the light source can also be improved by using a high-stability light source module.

[0123] By controlling the stability of the light source, the present invention ensures that the spectroscopic ellipsometer can obtain consistent optical signals during the measurement process, thereby improving the accuracy of the measurement.

[0124] Periodic recalibration means recalibrating the device after it has been used for a period of time to ensure that the measurement accuracy of the device has not decreased over time or with changes in the device status.

[0125] Equipment aging and environmental changes: With the long-term use of the spectroscopic ellipsometer, the aging of optical components, the attenuation of the light source, and the change in the sensitivity of the detector will lead to a decrease in the measurement accuracy of the equipment. In addition, changes in environmental conditions (such as temperature, humidity, etc.) may also affect the measurement results. Therefore, regular recalibration can timely detect and correct these effects and ensure that the equipment is always in the best measurement state.

[0126] Recalibration frequency: The recalibration frequency can be determined based on the frequency of use of the equipment, the measurement accuracy requirements, and changes in the production environment. For example, in a production environment with high precision requirements, recalibration can be performed once a quarter; in a stable environment, the recalibration frequency can be appropriately reduced.

[0127] By periodically recalibrating, the present invention ensures that the measurement accuracy of the spectroscopic ellipsometer is maintained for a long time, thereby providing reliable quality assurance in mass production.

[0128] The present invention stipulates that the actual aluminum oxide film sample should be measured using calibrated equipment to ensure the accuracy of all subsequent measurements. This requirement is intended to directly apply the results of calibration to actual production and measurement processes.

[0129] Ensure measurement accuracy: The measurement accuracy and consistency of calibrated spectroscopic ellipsometers have been verified. Therefore, using calibrated equipment in actual production can ensure that the measurement results of each batch of products are accurate and reliable and meet the predetermined quality standards.

[0130] Calibration feedback mechanism: When using a calibrated spectroscopic ellipsometer to measure actual samples, it is still necessary to regularly check the measurement results of the device. If the measurement results are abnormal, it may be necessary to recalibrate or adjust the device parameters. This feedback mechanism ensures that the device always maintains the best working condition and provides stable measurement results.

[0131] Example 1: Application of Spectroscopic Ellipsometer in High-Precision Semiconductor Thin Film Measurement

[0132] In the semiconductor manufacturing process, precise control of film thickness is crucial to device performance. As device size decreases, the precision requirements for film thickness are getting higher and higher, and usually need to be controlled at the sub-nanometer level. However, the measurement results of traditional spectroscopic ellipsometers under different operating conditions or between machines may produce significant differences, resulting in inconsistent film thickness control. Therefore, this embodiment aims to ensure that the measurement results of different machines remain highly consistent in high-precision semiconductor film measurement through the calibration method of the present invention, thereby improving the reliability of film thickness control in the production process.

[0133] The innovation of this embodiment is to achieve consistent film thickness measurement between different machines by using precise environmental control (temperature, humidity) and light source stability adjustment. In addition, the measurement accuracy of the spectroscopic ellipsometer in long-term use is ensured by regular recalibration. This embodiment is mainly used in the process links in the semiconductor manufacturing process that have extremely high requirements for film thickness, such as the deposition and detection of the gate oxide layer.

[0134] Comparative experiment:

[0135] In order to verify the superiority of the present invention, we conducted several comparative experiments to compare the consistency of film thickness measurement under different temperature and humidity conditions between the present invention and the traditional calibration method. The experimental settings are as follows:

[0136] Experimental conditions: Two spectroscopic ellipsometers A and B were used to measure the same standard film samples under different environmental conditions (temperatures of 20°C, 25°C, and 30°C, and humidity of 30%, 50%, and 70%, respectively).

[0137] Comparison items:

[0138] Standard deviation (SD) of the measurement results

[0139] Measurement consistency (differences in measurement results between different machines)

[0140] Long-term stability after calibration (error change after 100 measurements)

[0141] Experimental results show:

[0142]

[0143] Experimental results analysis:

[0144] It can be seen from the experimental results that under all environmental conditions, the calibration method of the present invention is significantly superior to the traditional method in terms of standard deviation, consistency and long-term stability. In particular, under high temperature and humidity, the measurement consistency and stability of the traditional method are significantly reduced, while the present invention can maintain stable measurement performance. This shows that the present invention can effectively reduce the impact of environmental conditions on the measurement results, ensure consistency between different machines, and is suitable for semiconductor manufacturing processes with extremely high requirements for film thickness.

[0145] Example 2: Application of Spectroscopic Ellipsometer in the Production of Large Optical Components

[0146] In the production process of large optical components, such as astronomical telescope lenses or high-precision optical lenses, the uniformity and consistency of film thickness directly affects the optical performance of the components. Due to the large size of these components, when using multiple spectroscopic ellipsometers for measurement, how to ensure the measurement consistency between different machines is a key issue. This embodiment aims to ensure that the measurement results of all machines are highly consistent in the production of large-size optical components through the calibration method of the present invention, thereby improving the overall quality of the optical components.

[0147] The innovation of this embodiment is to use the precise calibration method of the spectroscopic ellipsometer to ensure the consistency of the results of multiple machines in the measurement of large-scale samples through precise control of the light source intensity and regular recalibration. This embodiment is suitable for the production and inspection of large-scale optical components, such as high-precision lens coating thickness measurement.

[0148] Comparative experiment:

[0149] In order to verify the applicability of the present invention, we conducted a comparative experiment in the production of large optical components and compared the consistency of the present invention and the traditional method in the measurement of multiple machines. The experimental settings are as follows:

[0150] Experimental conditions: Three spectroscopic ellipsometers C, D, and E were used to measure different areas of the same large-scale optical component and compare the measurement results of different machines.

[0151] Comparison items:

[0152] Regional consistency of measurement results (differences in measurement results in different regions)

[0153] Measurement consistency across multiple machines

[0154] Repeated measurement error after calibration

[0155] Experimental results show:

[0156]

[0157] Experimental results analysis:

[0158] The experimental results show that the regional consistency and machine consistency of the present invention in the measurement of large-scale optical components are significantly better than those of traditional methods. In particular, in terms of the consistency of measurement results in different regions, the calibration method of the present invention greatly reduces the measurement differences between regions. In addition, the error of the calibration method of the present invention in repeated measurements is also significantly lower than that of the traditional method, which shows that it has a superior application effect in the production of large-scale optical components.

[0159] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calibrating aluminum oxide thin films for spectroscopic ellipsometer, characterized in that: The following steps are involved: S1: Select a film thickness standard sample, the sample includes a SiO2 film with a thickness of 1-3 nm and a silicon substrate, and ensure that the refractive index of the film is 1.457; S2: placing the film thickness standard sample at the center of the sample stage of the spectroscopic ellipsometer, and operating the spectroscopic ellipsometer to continuously measure the standard sample, with the number of measurements being no less than 5 times; S3: Calculate the average value of the measurement results and compare it with the known film thickness value of the film thickness standard sample to determine whether the measurement result is within the error range of ±0.15nm; S4: If the measurement result exceeds the error range of ±0.15nm, adjust the light source intensity and detector setting parameters of the spectroscopic ellipsometer and re-measure until the measurement result meets the requirements; S5: Use a calibrated spectroscopic ellipsometer to measure the thickness of actual aluminum oxide film samples to ensure consistent measurement results between different machines and minimize errors.

2. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 1, characterized in that: The substrate material of the film thickness standard sample is silicon, the film material is silicon dioxide, and the film thickness is 1-3nm. The error between the standard film thickness value and the actual measurement result is calculated, including the following calculation steps: Step 1: Calculate the average: in is the average of the measured values, X i is the i-th measurement value, n is the number of measurements; Step 2: Calculation error: Among them, E measurement is the measurement error, Y std It is the standard film thickness value.

3. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 2, characterized in that: In step S2, the measurement result of the standard sample is within the error range of ±0.15nm; the error range is determined as follows: if E measurement >0.15nm, the machine parameters need to be adjusted.

4. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 3, characterized in that: In the step S4, the light source intensity and the detector settings are adjusted to correct the measurement error. The adjusted machine parameters are based on the following algorithm: P adjusted =P current +ΔP, where P adjusted is the adjusted machine parameter, P current is the current machine parameter, and ΔP is the adjustment amount.

5. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 4, characterized in that: When calibrating the spectroscopic ellipsometer, the film thickness standard sample is placed in a clean room to reduce the impact of environmental factors on the measurement results; the error evaluation results of the re-measurement include: Remeasure and reassess: in is the average value after calibration, E final is the final measurement error; Calculate the consistency index: Where m is the number of machines, E final ,j is the measurement error of different machines; Calculate the comprehensive calibration index: I calibration =α·E final +β·C consistency , where α and β are weight coefficients used to balance the importance of error and consistency.

6. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 5, characterized in that: The film thickness standard sample is used for calibration of multiple spectroscopic ellipsometers to ensure that the measurement results of all machines are consistent. During the calibration process, the ambient temperature is controlled at 25±2° C. and the relative humidity is controlled between 40% and 60%.

7. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 6, characterized in that: In the step S3, the calibration accuracy of the spectroscopic ellipsometer is determined by calculating the average value of the measured values ​​and comparing them with the known values ​​of the standard film. During the measurement process, the stability of the light source is controlled within ±0.1% to ensure the accuracy of the measurement results.

8. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 7, characterized in that: The calibration process includes periodically recalibrating the spectroscopic ellipsometer to maintain its measurement accuracy.

9. The method for calibrating an aluminum oxide thin film for a spectroscopic ellipsometer according to claim 8, characterized in that: After the calibration is completed, the thickness of the aluminum oxide film is measured using a calibrated spectroscopic ellipsometer to ensure the accuracy of all subsequent measurements.

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