Measurement and microscopic light path coaxial deviation calibration method based on micro-area spectrum device

Abstract

The invention belongs to the technical field of optical measurement, and relates to an optical measurement technology of semiconductor nano-films and anisotropic film materials, in particular to a measurement and microscopic light path coaxial deviation calibration method based on a micro-area spectrum device. The micro-area spectrum device comprises a light path collimation module, an imaging module and a focusing module. The micro-area spectrum device comprises a light path collimation module, an imaging module and a focusing module. The measurement and microscopic light path coaxial deviation calibration method is based on a micro-area spectrum device, and comprises the following steps: S1, placing a resolution plate on a six-axis displacement table; and S2, executing a calibration step. In the aspect of transverse resolution, micron-level resolution is achieved, the size of a light spot incident to the surface of a sample is reduced to about 30 microns by adopting the combination of a precise pinhole and a low-magnification microscope system, so that micro-area measurement is realized, and the micron-level transverse resolution is finally achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical measurement, and relates to the optical measurement technology of semiconductor nano-thin films and anisotropic thin film materials, in particular to a calibration method for the coaxial deviation between the measurement and microscopic optical paths based on a micro-region spectroscopy device. Background Art

[0002] With the continuous progress of semiconductor technology and the development of Moore's law, the chip manufacturing process technology has been continuously evolving, and the size of chip devices has also been further reduced. This trend has sparked great enthusiasm among researchers for microscopic structures with unique properties, especially for the research of complex microscopic structures such as thin film materials with nanoscale thickness and high aspect ratio structures. For example, two-dimensional nanomaterials represented by graphene, transition metal chalcogenides, black phosphorus, etc., as well as metal thin films, semiconductor thin films, and high aspect ratio microstructures, have physical and chemical properties that are very different from traditional materials in terms of mechanical strength, electrical conductivity, thermal conductivity, and electron mobility. They are the basic materials that are key research targets in the fields of optoelectronics, microelectronics, new energy, semiconductors, etc. in the post-Moore era. As the size of microscopic structures decreases, the requirement for the lateral resolution of measurement is also increasing day by day.

[0003] The accurate characterization of microscopic structures is crucial for the performance evaluation, quality control, and application development of new materials. With the continuous reduction of device size, traditional measurement methods can no longer meet the requirements at the micron or even nanoscale. Especially in the research of two-dimensional nanomaterials, micro-region measurement not only helps to obtain the overall properties of materials, but also reveals local heterogeneity and its impact on performance. Due to its non-contact and non-destructive characteristics, optical measurement has increasingly become the preferred method for micro-region characterization. Especially in the fields of microelectronics and optoelectronics, non-contact optical measurement can efficiently and accurately perform micro-region characterization, avoiding material damage or deformation that may be caused by traditional methods. Therefore, as the size of microscopic structures further decreases, the importance of optical micro-region measurement technology becomes even more prominent. It not only promotes the basic research of new materials, but also provides key technical support for the efficient manufacturing and optimization of chips and optoelectronic devices.

[0004] However, in optical measurement methods, it is usually necessary to accurately position microscopic structures with the help of a CCD camera. In this process, a beam splitter (such as a parallel plate or BS) is usually used, which will inevitably cause a significant loss of light intensity. In addition, if a high-frequency modulation device, such as a photoelastic modulator, is used in the optical path, since the exposure time of traditional CCD cameras or CMOS cameras is usually in the millisecond level, which is much lower than the modulation frequency of the photoelastic modulator, the accurate positioning of microscopic structures cannot be achieved. This limitation significantly restricts its application in the characterization of micron-scale microscopic structures. Especially in high-resolution measurements, it is difficult to provide sufficient time resolution to accurately capture rapidly changing optical signals. Summary of the Invention

[0005] The present invention provides a calibration method for the coaxial position deviation of the micro-region measurement and imaging illumination optical path in a reflection spectroscopy system. By adopting the disassembly and assembly of the beam splitter and the pixel point calibration mode, this method effectively avoids light intensity loss while accurately calibrating and removing the micron-level shift of the light spot caused by the beam splitter. This significantly improves the characterization accuracy of the system for microscopic structures, ensures the consistency of the light spot position, and thus improves the stability and reliability of the measurement. This calibration method not only eliminates the measurement error caused by the optical path deviation but also enhances the high-precision ability of the system in micro-region measurement by avoiding light intensity loss. The present invention is applicable to the accurate characterization of microscopic structures in reflection spectroscopy systems and has broad industrial application potential, especially in the field of industrial characterization of microscopic structures.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a micro-region spectroscopy device, including an optical path collimation module, an imaging module, and a focusing module;

[0007] The optical path collimation module successively includes: a broadband light source, an off-axis parabolic mirror, and a precision pinhole;

[0008] The imaging module successively includes: a CCD camera, a first beam splitter, a second beam splitter, and an illumination light source;

[0009] The focusing module successively includes: a microscope system and a six-axis displacement stage;

[0010] The off-axis parabolic mirror collimates the measurement beam emitted by the broadband light source to generate a parallel measurement beam; the second beam splitter transmits the measurement light and the illumination light emitted by the illumination light source into the microscope system, and the microscope system converges the incident light onto the sample; the first beam splitter transmits the measurement light and the illumination light reflected by the sample into the CCD camera, and the six-axis displacement stage is used to carry the sample and drive the sample to translate and rotate in the horizontal and vertical planes.

[0011] Preferably, the micro-region spectroscopy device further includes a pull rod for pulling the first beam splitter and the second beam splitter out of the measurement optical path.

[0012] The calibration method for the coaxial deviation between the measurement (optical path) and the microscopic optical path, based on the above micro-region spectroscopy device, includes the following steps:

[0013] S1. Place the resolution plate on the six-axis displacement stage;

[0014] S2. Execute the calibration step.

[0015] Among them, the calibration step in step S2 specifically includes:

[0016] S21. Install the first beam splitter and the second beam splitter so that at this time, both the measurement light emitted by the broadband light source and the illumination light emitted by the illumination light source can be received by the CCD camera. The data collected by the CCD camera is uploaded to the computer and made into a bitmap by software;

[0017] S22. Use the resolution target board to make the measurement spot fill the short side of a certain test bar on the resolution target board at this time, and record the position coordinates of the measurement spot at this time;

[0018] S23. Use the telescopic rod to remove the first beam splitter and the second beam splitter, and adjust the six-axis displacement stage to make the measurement spot return to the coordinate position in the calibration step S22;

[0019] S24. Use the telescopic rod to reinstall the first beam splitter and the second beam splitter, and compare the position coordinates of the measurement spot on the resolution target board at this time with the position coordinates of the measurement spot in step S22;

[0020] S25. Use pixel points of the same size as the measurement spot to fill the pixel area of the measurement spot in step S24 to complete the calibration process.

[0021] Due to the above technical solutions adopted by the present invention, compared with the prior art, it has the following advantages:

[0022] 1. In terms of the lateral resolution, the present invention achieves a micron-level resolution: by adopting the combination of a precision pinhole and a low-magnification microscope system, the spot size incident on the sample surface is reduced to about 30 μm, thereby realizing micro-area measurement and finally achieving a micron-level lateral resolution.

[0023] 2. Realize the enhancement of light intensity in the microscopic structure: By removing the beam splitter in this design, the problem of light intensity loss caused by the beam splitting effect of the beam splitter in micro-area measurement is solved, the signal quality is improved, thereby enhancing the light intensity in micro-area measurement and improving the overall sensitivity and measurement accuracy of the system.

[0024] 3. Realize the precise positioning of the sample in micro-area measurement: This design adopts the method of pixel point calibration to accurately calibrate the micron-level position offset of the spot after removing the beam splitter, ensuring the precise alignment of the measurement spot and the sample surface. Through this method, the sample can be precisely positioned during the micro-area measurement process, thereby improving the accuracy and stability of the measurement position;

[0025] 4. Due to the introduction of the beam splitter, a slight deviation may occur in the coaxial position in the optical path, resulting in inconsistent spot positions of the illumination light and the measurement light. This position deviation will cause a deviation in the path of the light beam, thereby affecting the accuracy of the spot, and further affecting the stability and accuracy of the measurement. Especially in micro-area measurement, a very small deviation may lead to significant measurement errors. In order to avoid light intensity loss and improve measurement accuracy, the present invention provides a calibration method for the coaxial position deviation between the micro-area measurement and the microscopic optical path in a micro-area spectroscopy system. This method can accurately calibrate and eliminate the spot position deviation introduced by the beam splitter, thereby ensuring that the spots of the illumination light and the measurement light are in the same position in space, further improving the accuracy and reliability of the system in micro-area measurement, and avoiding light intensity loss, thus effectively enhancing the measurement ability of the micro-area spectroscopy system at high resolution and high precision. Description of the Drawings

[0026] Figure 1 It is a structural diagram of a calibration device for the coaxial position deviation between the micro-area measurement and the imaging illumination optical path of a reflection spectroscopy system;

[0027] Figure 2 It is a micrograph of the measured spot size.

[0028] The names of the components represented by the reference numerals in the above drawings are as follows:

[0029] 1. Wide-spectrum light source; 2. Off-axis parabolic mirror; 3. Precision pinhole; 4. First beam splitter; 5. Second beam splitter; 6. Microscope system; 7. Six-axis displacement stage; 8. CCD camera; 9. Illumination light source; 10. Pull-out rod. Detailed Embodiments

[0030] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described below with reference to the drawings and embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

[0031] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention may be implemented in other ways different from those described herein. Therefore, the present invention is not limited by the specific embodiments disclosed in the following specification.

[0032] As Figure 1 、 Figure 2 shown, the micro-area spectroscopy device includes: an optical path collimation module, an illumination module, and a focusing module;

[0033] The optical path collimation module sequentially includes: a wide-spectrum (ultraviolet to near-infrared) light source 1, an off-axis parabolic mirror 2, and a precision pinhole 3;

[0034] The optical path modulation module sequentially includes: an illumination light source 9, a first beam splitter 4, a second beam splitter 5, and a CCD camera 8;

[0035] The focusing module sequentially includes: a microscope system 6, a six-axis displacement stage 7;

[0036] This measurement method is for the positioning of microscopic structure samples. Usually, the sample is placed on the six-axis displacement stage 7 under the microscope system 6. The measurement beam and the illumination beam enter the CCD camera 8 through the first beam splitter 4 and the second beam splitter 5 to complete the positioning of the microscopic structure sample.

[0037] Furthermore, this device also includes a pull rod 10 for removing the first beam splitter 4 and the second beam splitter 5 from the measurement optical path.

[0038] The calibration method for the coaxial deviation between the measurement (optical path) and the microscopic optical path, based on the above micro-region spectral device, includes the following steps:

[0039] S1. Place the resolution target on the six-axis displacement stage 7;

[0040] S2. Execute the calibration step.

[0041] Among them, the calibration step in step S2 specifically includes:

[0042] S21. Install the first beam splitter 4 and the second beam splitter 5 so that the measurement light emitted by the broadband light source and the illumination light emitted by the illumination light source 9 can both be received by the CCD camera 8. The data collected by the CCD camera 8 is uploaded to the computer and made into a bitmap by software;

[0043] S22. Use the resolution target to make the measurement spot fill the short side of a certain test target bar on the resolution target, and record the position coordinates of the measurement spot at this time;

[0044] S23. Use the pull rod 10 to remove the first beam splitter 4 and the second beam splitter 5, and adjust the six-axis displacement stage 7 to make the measurement spot return to the coordinate position in the calibration step S22;

[0045] S24. Use the pull rod 10 to reinstall the first beam splitter 4 and the second beam splitter 5, and compare the position coordinates of the measurement spot on the resolution target at this time with the position coordinates of the measurement spot in step S22;

[0046] S25. Use pixel points of the same size as the measurement spot to fill the pixel area of the measurement spot in step S24 to complete the calibration process.

[0047] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A micro-area spectroscopy device, characterized in that: It includes an optical path collimation module, an imaging module, and a focusing module; The optical path collimation module includes: a wide spectrum light source, an off-axis parabolic mirror, and a precision pinhole; The imaging module includes in sequence: a CCD camera, a first beam splitter, a second beam splitter, and an illumination light source; The focusing module includes: a microscope system and a six-axis translation stage.

2. The micro-area spectroscopy device according to claim 1, characterized in that: It also includes a pulling rod for pulling the first beam splitter and the second beam splitter out of the measuring light path.

3. A method for measuring and calibrating the coaxial deviation of a microscopic optical path, based on the micro-area spectroscopy device as claimed in claim 1, characterized in that: The following steps are involved: S1. Place the resolution board on the six-axis translation stage; S2. Execute calibration steps. The calibration step in step S2 specifically includes: S21, installing a first beam splitter and a second beam splitter so that the measurement light emitted by the wide spectrum light source and the illumination light emitted by the illumination light source can be received by the CCD camera, and the data collected by the CCD camera is uploaded to the computer and made into a bitmap by the software; S22, using a resolution board, so that the measurement spot now fills the short side of a test target strip on the resolution board, and recording the position coordinates of the measurement spot now; S23, removing the first beam splitter and the second beam splitter by pulling out the support rod, and adjusting the six-axis translation stage to make the measurement spot return to the coordinate position in the calibration step S22; S24, reinstall the first beam splitter and the second beam splitter by pulling out the support rod, and compare the position coordinates of the measuring spot position on the resolution plate at this time with the position coordinates of the measuring spot position in step S22; S25, using pixel points with the same size as the measurement spot to fill the measurement spot pixel area in step S24 to complete the calibration process.

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