Online calibration method and apparatus for spectrometers

Abstract

Various embodiments of this disclosure relate to an online calibration method and apparatus for a spectrometer, wherein the online calibration method includes: placing a first aperture, a second aperture, and a first reflector in a predetermined optical path leading to the spectrometer; adjusting at least one of the first aperture, the second aperture, and the first reflector to thereby determine the optical axis of the predetermined optical path; using a second reflector to couple standard light emitted from a standard light source located outside the predetermined optical path into the predetermined optical path to be emitted toward the spectrometer along the determined optical axis; and calibrating the spectrometer using the standard light. Using the method of this disclosure, online calibration of a spectrometer can be achieved.

Description

Technical Field

[0001] The embodiments of this disclosure relate to the field of optics, and more specifically to online calibration methods and apparatus for spectrometers. In particular, the spectrometer is suitable for use in film thickness measurement equipment (e.g., ellipsometers) in semiconductor large-scale integrated circuit manufacturing. Background Technology

[0002] Ellipsometry is a highly practical optical technique. It is a non-contact, non-destructive measurement method used to measure thin film thickness, optical constants, reflectivity, surface microstructure, roughness, and more. It has wide applications in physics, chemistry, biology, medicine, semiconductors, and other fields. The value obtained by ellipsometric measurement is the sum of two complex reflection coefficients R. P and R S The ratio:

[0003]

[0004] Where δ p and δ s It is R p and R s The phase, Ψ and Δ are elliptic parameters.

[0005] Ellipsometry can be divided into single-wavelength ellipsometrics and multi-wavelength spectral ellipsometrics. The spectrometer is the element in spectral ellipsometric equipment that acquires the intensity of the light signal; the accuracy of the spectrometer's wavelength calibration directly affects the accuracy of the ellipsometric measurement results. Spectrometer calibration requires the use of characteristic spectral lines from low-pressure mercury lamps and argon lamps. Figure 1 The characteristic spectral lines of a standard light source, such as a mercury-argon lamp, are shown.

[0006] Traditional spectrometer calibration is performed offline (e.g., detached from the sample or measuring equipment). The method involves directly connecting the output light from a mercury-argon lamp to the spectrometer; then, based on the characteristic spectrum of the mercury-argon lamp and the corresponding pixels of the CCD, a polynomial fitting is used to derive the relationship between wavelength and pixels, thereby performing spectral calibration. For example, the quadratic polynomial used for fitting is shown below:

[0007] λ = ax 2 +bx+c

[0008] Where λ is the wavelength and x is the number of pixels in the CCD.

[0009] However, in practical sample measurement applications (i.e., online applications), the spectrometer after offline calibration may require position and orientation adjustments to receive the light signal reflected from the sample. This can lead to angular and positional errors in the incident light signal, deviating from the ideal state of offline calibration and causing wavelength drift, thus resulting in measurement deviations. Therefore, online recalibration is often necessary. Summary of the Invention

[0010] One of the objectives of this disclosure is to provide an online calibration method and apparatus for spectrometers, which can at least overcome or mitigate the measurement deviations caused by existing spectrometers deviating from the ideal state of offline calibration.

[0011] According to a first aspect of this disclosure, an online calibration method for a spectrometer is provided, wherein the spectrometer is located in a predetermined optical path of a measuring device for analyzing the characteristics of light from the predetermined optical path. The online calibration method includes: placing a first aperture, a second aperture, and a first reflector in the predetermined optical path leading to the spectrometer; adjusting at least one of the first aperture, the second aperture, and the first reflector such that light from a main light source of the measuring device traveling along the predetermined optical path can sequentially pass through the first aperture and the second aperture and be incident on the first reflector, and such that reflected light from the first reflector can sequentially pass through the second aperture and the first aperture, thereby determining the optical axis of the predetermined optical path; using the second reflector to reflect standard light emitted from a standard light source located outside the predetermined optical path into the predetermined optical path, and causing the reflected standard light to be emitted toward the spectrometer along the determined optical axis; and calibrating the spectrometer using the standard light.

[0012] The online calibration method disclosed herein can be advantageously used to calibrate spectrometers online, thereby improving the accuracy of the measuring equipment. Furthermore, the calibration method of this disclosure is simple to operate and can quickly achieve online calibration of the spectrometer.

[0013] In some embodiments, using a second reflector to reflect standard light emitted from a standard light source located outside the predetermined optical path into the predetermined optical path, and to cause the reflected standard light to be emitted toward the spectrometer along a determined optical axis, may further include: placing the second reflector on the predetermined optical path to reflect the standard light emitted from the standard light source into the predetermined optical path; adjusting the second reflector and / or the standard light source such that the standard light reflected by the second reflector can sequentially pass through the first aperture and the second aperture and be incident on the first reflector, and such that the standard light reflected by the first reflector can sequentially pass through the second aperture and the first aperture, thereby determining that the optical axis of the beam emitted from the standard light source and reflected by the second reflector coincides with the optical axis of the beam in the predetermined optical path; and removing the first reflector from the predetermined optical path so that the standard light emitted from the standard light source enters the spectrometer. In this way, it is easy to ensure that the optical axis of the optical path emitted from the standard light source is aligned with the optical axis of the predetermined optical path; and that standard light along the optical axis of the predetermined optical path is input into the spectrometer.

[0014] In some embodiments, the step of placing the first aperture, the second aperture, and the first mirror on the predetermined optical path leading to the spectrometer may include any of the following: placing the first aperture and the second aperture in the incident optical path before incident on the sample; or placing the first aperture and the second aperture in the receiving optical path for receiving light emitted from the sample. In this way, flexible arrangement of the first aperture, the second aperture, and the first mirror on the predetermined optical path is provided.

[0015] In some embodiments, placing the first aperture, the second aperture, and the first mirror in the predetermined optical path leading to the spectrometer may include placing the first mirror in a receiving optical path of the predetermined optical path for receiving light emitted from the sample, and at a position adjacent to the spectrometer. In this way, it can be ensured that the optical path of the standard light near the spectrometer is consistent with the predetermined optical path.

[0016] In some embodiments, placing the second reflector in the predetermined optical path may include either placing the second reflector in the incident optical path before it reaches the sample, or placing the second reflector in the receiving optical path for receiving light emitted from the sample. This provides flexibility in the arrangement of the second reflector.

[0017] In some embodiments, the first aperture may be a variable aperture or a pinhole, and the second aperture may be a variable aperture or a pinhole. In the pinhole embodiment, the light from the main light source and / or standard light source of the measuring device can be passed through simply by adjusting the position of the pinhole.

[0018] In some embodiments, when both the first and second apertures are variable apertures, the step of adjusting at least one of the first aperture, the second aperture, and the first reflector includes: reducing the aperture of both the first and second apertures to their respective predetermined values; and determining the optical axis of the predetermined optical path while ensuring that the reflected light can still pass through the reduced apertures of the first and second apertures. Determining the optical axis of the predetermined optical path by reducing the aperture can further improve the accuracy of the optical axis determination.

[0019] In some embodiments, the spectrometer may exist independently as a receiver in addition to the measuring device, or the spectrometer may be part of the measuring device.

[0020] In some embodiments, the measuring device may be a film thickness measuring device. This film thickness measuring device may be, for example, an ellipsometer.

[0021] According to a second aspect of this disclosure, an online calibration apparatus for a spectrometer is provided. This online calibration apparatus is used to perform online calibration of the spectrometer located on a predetermined optical path of a measuring device. The online calibration apparatus includes at least the following components: a movable first aperture, a second aperture, and a first reflector, configured to be operably moved to appropriate positions on the predetermined optical path leading to the spectrometer from the measuring device during online calibration, such that light from a main light source of the measuring device traveling along the predetermined optical path can sequentially pass through the first aperture and the second aperture and be incident on the first reflector, and that reflected light from the first reflector can sequentially return through the second aperture and the first aperture, thereby determining the optical axis of the predetermined optical path; a standard light source, disposed outside the predetermined optical path and configured to emit standard light for calibrating the spectrometer; and a movable second reflector configured to operably reflect the standard light into the predetermined optical path during online calibration, and to cause the reflected standard light to be emitted toward the spectrometer along the determined optical axis, thereby achieving the calibration of the spectrometer.

[0022] In some embodiments, the movable second reflector may also be configured to be operably moved onto the predetermined optical path such that the standard light reflected by the second reflector can pass sequentially through the first aperture and the second aperture and be incident on the first reflector, and that the standard light reflected by the first reflector can return sequentially through the second aperture and the first aperture.

[0023] In some embodiments, the first aperture is a variable aperture or a pinhole, the second aperture is a variable aperture or a pinhole, and the first reflector is a plane reflector.

[0024] In some embodiments, the spectrometer exists independently as a receiver of the measuring device, or the spectrometer is part of the measuring device.

[0025] According to a third aspect of this disclosure, a measuring device is provided. This measuring device includes an online calibration apparatus as described in the second aspect, thereby enabling online calibration of the measuring device.

[0026] In some embodiments, the measuring device is a film thickness measuring device. As an example, the film thickness measuring device is an ellipsometer.

[0027] It should be understood that the description in the Summary of the Invention is not intended to limit the key or essential features of the embodiments of this disclosure, nor is it intended to restrict the scope of this disclosure. Other features of the embodiments of this disclosure will become readily apparent from the following description. Attached Figure Description

[0028] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. In the drawings, the same or similar reference numerals denote the same or similar elements.

[0029] Figure 1 The characteristic spectral lines of a mercury-argon lamp, used as a standard light source, are shown.

[0030] Figure 2 A schematic diagram of the structure for online calibration of a spectrometer according to a first embodiment of the present disclosure is shown.

[0031] Figure 3 A schematic diagram of the structure for online calibration of a spectrometer according to a second embodiment of the present disclosure is shown.

[0032] Figure 4 A schematic diagram of the structure for online calibration of a spectrometer according to a third embodiment of the present disclosure is shown.

[0033] Figure 5 A flowchart of an online calibration method for a spectrometer according to various embodiments of the present disclosure is shown. Detailed Implementation

[0034] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0035] The embodiments of this disclosure provide an online calibration method and apparatus for a spectrometer, aiming to achieve online calibration of the spectrometer. It should be noted that the term "online calibration" herein refers to the calibration of the spectrometer based on the presence of an actual sample in the optical path, or on the spectrometer being on a measuring device, thus distinguishing it from offline calibration (where the actual sample or measuring device is not being measured). Furthermore, it will be understood that online calibration of the spectrometer is performed in conjunction with a measuring device (e.g., a film thickness measuring device) used to measure the characteristics of the sample, wherein the spectrometer may be part of the measuring device or exist as a receiver outside of the measuring device.

[0036] It will be understood that the concept of this disclosure is as follows: First, the optical axis of the measuring device is calibrated using two apertures and a reflector located before the spectrometer. Then, standard light emitted by a standard light source is incident on the spectrometer along the determined optical axis to achieve spectrometer calibration. Specifically, for example, the optical axis of the predetermined optical path can be determined by placing a first aperture, a second aperture, and a first reflector on a predetermined optical path leading to or upstream of the spectrometer, such that light from the main light source of the measuring device traveling along the predetermined optical path can sequentially pass through the first aperture and the second aperture and be incident on the first reflector, and that reflected light from the first reflector can sequentially return through the second aperture and the first aperture, thereby determining the optical axis of the predetermined optical path; and the standard light emitted by the standard light source is coupled into or introduced into the predetermined optical path along the determined optical axis using the second reflector, thereby using the standard light to calibrate the spectrometer. It will be understood that through the above steps, the optical path of the standard light source entering the spectrometer can be strictly aligned with the optical path of the light source of the measuring device entering the spectrometer, thereby achieving the purpose of calibrating the spectrometer at the current position.

[0037] The following will be combined with measuring equipment (e.g., film thickness measuring equipment) and referenced. Figures 2 to 4 This section describes various embodiments of the online calibration method and apparatus for the spectrometer disclosed herein. It should be noted that... Figures 2 to 4 The measuring device shown is merely an example; in other application scenarios, the structure and / or optical path of the measuring device may differ.

[0038] Figure 2 A schematic diagram of the structure for online calibration of a spectrometer according to a first embodiment of the present disclosure is shown.

[0039] For example only, such as Figure 2 As shown, the measuring device 20 may include a light source 1, a polarizer 2, a focusing lens 3, a collecting lens 5, an analyzer 6, a focusing lens 7, and a spectrometer 8. The polarizer 2 converts light from the light source 1 into polarized light, the focusing lens 3 then focuses the polarized light onto the sample 4, and the collecting lens 5 collects light scattered, reflected, or diffracted from the sample 4, which is then analyzed by the analyzer 6 and focused by the focusing lens 7 before being incident on the spectrometer 8. It should be understood that the inclusion of the spectrometer 8 in the measuring device 20 is not essential; in other embodiments, the spectrometer 8 may exist independently as a receiver outside the measuring device 20. It should also be understood that the light collected from the sample 4 contains information characterizing key parameters of the sample (e.g., film thickness, grating size, etc.), and therefore, the key parameters of the sample can be obtained by analyzing the light from the sample 4 using the spectrometer 8. Furthermore, in other embodiments, the measuring device 20 is not limited to the above-described embodiments. Figure 2 The structure and arrangement shown may not be limited to the optical components shown, but may include other different, more or fewer optical components.

[0040] As described in the background section, the position of the spectrometer may be adjusted or moved during actual measurements, deviating from the ideal state of offline calibration. This results in wavelength drift and consequently, measurement result bias. Therefore, online calibration of the spectrometer may be desirable during actual measurements.

[0041] In order to achieve online calibration of the spectrometer 8, the calibration method disclosed herein first includes: using a first aperture 11, a second aperture 12 and a first reflector 13 to determine the optical axis of the predetermined optical path from the measuring device 20 to the spectrometer 8.

[0042] Specifically, such as Figure 2 As shown, for example, the first aperture 11 and the second aperture 12 can be placed in the incident light path before the sample 4 in the predetermined light path, and the first reflector 13 can be placed in the receiving light path of the light emitted from the sample 4 in the predetermined light path.

[0043] As an example only, the first aperture 11 can be placed between the light source 1 and the polarizer 2 of the test device 20, and the second aperture 12 can be placed between the polarizer 2 and the focusing lens 3. It should be understood that placing the first aperture 11 and the second aperture 12 at other locations in the incident light path is also possible. For example, both the first aperture 11 and the second aperture 12 can be placed between the light source 1 and the polarizer 2, or both can be placed between the polarizer 2 and the focusing lens 3. Meanwhile, the first mirror 13 can be placed at any location in the receiving light path for receiving light emitted from the sample in the predetermined light path, for example, between the analyzer 6 and the focusing lens 7. In particular, the first mirror 13 can be placed close to the focusing lens 7, which allows the first mirror 13 to be as close as possible to the spectrometer 8. This is advantageous for ensuring the accuracy of determining the optical axis directly upstream of the spectrometer, as described later.

[0044] Furthermore, with the aforementioned arrangement of the first aperture 11, the second aperture 12, and the first reflector 13, the optical axis of the predetermined optical path can be determined, for example, by adjusting at least one of the first aperture 11, the second aperture 12, and the first reflector 13 (e.g., by moving at least one of the first aperture 11, the second aperture 12, and the first reflector 13 through a two-dimensional translation). This allows light from the main light source 1 of the measuring device 20, traveling along the predetermined optical path, to sequentially pass through the first aperture 11 and the second aperture 12 and be incident on the first reflector 13, and allows reflected light from the first reflector 13 to sequentially return through the second aperture 12 and the first aperture 12, thereby determining the optical axis of the predetermined optical path. It will be understood that, in this case, the line connecting the centers of the first aperture 11 and the second aperture 12 can be determined as the optical axis of the predetermined optical path.

[0045] In some embodiments, the first aperture 11 and the second aperture 12 may be a variable aperture or a pinhole.

[0046] In embodiments where the first aperture 11 and the second aperture 12 are variable apertures, the step of adjusting at least one of the first aperture 11, the second aperture 12, and the first reflecting mirror 13 may further include: reducing the apertures of both the first aperture 11 and the second aperture 12 to their respective predetermined values ​​(e.g., minimum values ​​of 1 mm and 0.5 mm), and if the reflected light via the first reflecting mirror 13 can still return through the reduced apertures of the first aperture 11 and the second aperture, the optical axis of the predetermined optical path can be determined more accurately. It will be understood that, in this case, the line connecting the centers of the reduced apertures of the first aperture 11 and the second aperture 12 can be more accurately determined as the optical axis of the predetermined optical path.

[0047] Once the optical axis of the predetermined optical path is determined, the calibration method disclosed herein may further include: using the second reflector 10 to introduce or couple standard light emitted by a standard light source 9 located outside the predetermined optical path into the predetermined optical path, and causing the reflected standard light to be emitted toward the spectrometer 8 along the determined optical axis; and using the standard light to calibrate the spectrometer 8.

[0048] More specifically, utilizing the second reflector 10 may include: placing the second reflector 10 in a predetermined optical path to reflect standard light emitted by a standard light source 9 positioned outside the predetermined optical path back to the predetermined optical path; adjusting the second reflector 10 (e.g., adjusting the angle of the second reflector) and / or the standard light source 9 (e.g., adjusting the position of the standard light source 9) such that the standard light reflected by the second reflector 10 can sequentially pass through the first aperture 11 and the second aperture 12 and be incident on the first reflector 13, and such that the standard light reflected by the first reflector 13 can sequentially return through the second aperture 12 and the first aperture 11, thereby ensuring that the optical axis of the beam emitted from the standard light source and reflected by the second reflector coincides with the optical axis of the beam in the predetermined optical path of the measuring device; and after ensuring that the two optical axes coincide, removing the first reflector from the predetermined optical path to allow the standard light emitted from the standard light source to enter the spectrometer, thereby calibrating the spectrometer.

[0049] In some embodiments, placing the second reflector 10 in the predetermined optical path may include placing the second reflector 10 in the incident optical path before it is incident on the sample 4. This is merely an example. Figure 2 As shown, the second reflector 10 can be placed at an appropriate position in the incident light path, between the main light source 1 and the polarizer 11. However, it will be understood that this is not a limitation, and the second reflector 10 can also be placed at other positions in the incident light path, in which case the positions of the first aperture 11, the second aperture 12, and the standard light source 10 can be adjusted accordingly.

[0050] Furthermore, despite Figure 2 The second reflector 10 is shown as a single planar reflector; however, it should be understood that this is not a limitation. In other embodiments, the second reflector 10 may also be a non-planar reflector or a combination of multiple planar and / or non-planar reflective devices.

[0051] Figure 3 A schematic diagram of the structure for online calibration of a spectrometer according to a second embodiment of the present disclosure is shown. Figure 3 The second embodiment and Figure 2 The only difference in the first embodiment is that the first aperture 11 and the second aperture 12 are instead placed in the receiving optical path of the predetermined optical path for receiving light emitted from the sample 4.

[0052] For example only, such as Figure 3 As shown, the first aperture 11 and the second aperture 12 can be placed between the analyzer 6 and the focusing lens 7. However, it will be understood that this is not a limitation, and it is possible for the first aperture 11 and the second aperture 12 to be placed in other positions in the receiving optical path. For example, the first aperture 11 and the second aperture 12 can also be placed between the collecting lens 5 and the analyzer 6, or the first aperture 11 can be placed between the collecting lens 5 and the analyzer 6, while the second aperture 12 can be placed between the analyzer 6 and the focusing lens 7. It will be understood that... Figure 3 The embodiments advantageously provide Figure 2 Variations of the embodiments.

[0053] Figure 4 A schematic diagram of the structure for online calibration of a spectrometer according to a third embodiment of the present disclosure is shown. Figure 4 The third embodiment and Figure 3 The second embodiment differs only in that the second reflector 10 is instead placed in the receiving optical path of the predetermined optical path for receiving light emitted from the sample 4, so as to reflect standard light from the corresponding standard light source 10 into the receiving optical path.

[0054] For example only, such as Figure 4 As shown, the second reflector 10 can be placed between the collecting lens 5 and the analyzer 6. However, it will be understood that this is not a limitation, and the second reflector 10 can be placed in other positions in the receiving optical path. For example, it is possible for the second reflector 10 to be placed between the analyzer 6 and the focusing lens 7, in which case the first aperture 11, the second aperture 12, and the standard light source 9 will be adjusted accordingly. It will be understood that... Figure 4 The embodiments also advantageously provide Figure 2 Variations of the embodiments.

[0055] The schematic structural arrangement for implementing the online calibration method for the spectrometer disclosed herein has been described in detail above. It should be understood that placing the first aperture 11, the second aperture 12, the first reflector 13, and the second reflector 10 in the above manner, and making corresponding adjustments, ensures that the optical path of the standard light source 9 and the optical path of the test equipment 20 are strictly aligned, at least from the second reflector 10 onwards. In particular, placing the first reflector 13 closer to the focusing lens 7 (and thus closer to the spectrometer 8), and placing the second reflector 10 closer to the main light source 1, may be more advantageous, as this allows the optical path of the standard light source 9 to follow the optical path of the test equipment as closely as possible, thereby achieving more accurate calibration of the spectrometer.

[0056] The following will refer to Figure 5The procedure for online calibration of the spectrometer disclosed herein will be briefly described.

[0057] like Figure 5 As shown, the method includes: placing a first aperture 11, a second aperture 12 and a first reflector 13 in block 510 on the predetermined optical path of the measuring device 20 leading to the spectrometer 8.

[0058] It should be understood that the measuring device 20 may include, but is not limited to, a film thickness measuring device, such as an ellipsometer, and the spectrometer 8 may or may not be part of the measuring device 20. For example, the spectrometer 8 may exist as a receiver outside of the measuring device 20.

[0059] In some embodiments, the steps in block 510 can be implemented in the following manner:

[0060] The first and second apertures are placed in the incident optical path before the light is incident on the sample in the predetermined optical path, or the first and second apertures are placed in the receiving optical path for receiving light emitted from the sample in the predetermined optical path; and

[0061] The first reflecting mirror 13 is placed in the incident light path or the receiving light path. In either case, the two apertures are located downstream of the first aperture, and the first reflector is located downstream of the second aperture.

[0062] In some embodiments, the first aperture and the second aperture can both be variable apertures or pinholes; the first reflector can be a plane mirror.

[0063] In frame 520, at least one of the first aperture 11, the second aperture 12, and the first reflector 13 is adjusted such that light from the main light source 1 of the measuring device 20, traveling along the predetermined optical path, can sequentially pass through the first aperture 11 and the second aperture 12 and be incident on the first reflector 13, and that reflected light from the first reflector 13 can sequentially return through the second aperture 12 and the first aperture 11, thereby determining the optical axis of the predetermined optical path.

[0064] It will be understood that the above adjustments may include translation (e.g., two-dimensional translation), rotation (e.g., adjusting the angle of the mirror) of at least one of the first aperture 11, the second aperture 12, and the first reflector 13. In embodiments where both the first and second apertures are variable apertures, the above adjustments may further include reducing the apertures of both the first and second apertures to their respective predetermined values. Once the reflected light can still pass through the reduced apertures of the first and second apertures, the optical axis of the predetermined optical path can be more accurately determined.

[0065] In frame 530, the standard light emitted by the standard light source 9, which is located outside the predetermined optical path, is reflected into the predetermined optical path using the second reflector 10, so that the reflected standard light is emitted toward the spectrometer 8 along the determined optical axis.

[0066] In some embodiments, utilizing the second reflector 10 may include the following operations:

[0067] The second reflector is placed in the predetermined optical path to reflect the standard light emitted by the standard light source into the predetermined optical path;

[0068] Adjust the second reflector and / or the standard light source such that the standard light reflected by the second reflector can sequentially pass through the first aperture and the second aperture and be incident on the first reflector, and that the standard light reflected by the first reflector can sequentially return through the second aperture and the first aperture, thereby ensuring that the optical axis of the beam emitted from the standard light source and reflected by the second reflector coincides with the optical axis of the beam in the predetermined optical path of the measuring device; and

[0069] The first reflector is removed from the predetermined optical path so that the standard light emitted from the standard light source enters the spectrometer.

[0070] The above operations can ensure that the standard light from the standard light source can be incident on the spectrometer according to the optical axis of the predetermined optical path, thereby realizing online calibration of the spectrometer at the current location.

[0071] In frame 540, the spectrometer is calibrated using the standard light.

[0072] In some embodiments, this step may include: reading the spectrum from the spectrometer, and then obtaining a relationship curve between the number of pixels of the spectrometer's CCD and the characteristic spectral peaks of the standard light source based on the characteristic peaks of the standard light source. Then, a quadratic polynomial fitting is performed on the pixels of the spectrometer's CCD to achieve online calibration of the spectrometer. As an example only, the formula for this quadratic polynomial is as follows:

[0073] λ = ax 2 +bx+c

[0074] Where λ is the wavelength and x is the number of pixels in the CCD.

[0075] The online calibration method for a spectrometer has been described in detail above. This disclosure may also relate to an online calibration device for a spectrometer. It will be understood that the online calibration device of this disclosure may be integrated into the aforementioned measuring equipment or provided to the measuring equipment in the form of a kit.

[0076] Specifically, the online calibration device may include at least the following components or a kit of the following components: a first aperture 11, a second aperture 12, a first reflector 13, a standard light source 9, and a second reflector 10. In embodiments integrated into the measuring device, these components may be mounted within the housing of the measuring device, for example, on the base plate of a measuring device such as a film thickness measuring device, just like other components of the measuring device.

[0077] During online calibration, the first aperture 11, the second aperture 12, and the first reflector 13 can be moved (e.g., driven by a motor or manually actuated) to appropriate positions on the predetermined optical path of the measuring device leading to the spectrometer. This allows light from the main light source of the measuring device, traveling along the predetermined optical path, to pass sequentially through the first aperture and the second aperture and be incident on the first reflector, and allows reflected light from the first reflector to return sequentially through the second aperture and the first aperture, thereby determining the optical axis of the predetermined optical path. Simultaneously, the position and / or orientation and / or rotation angle of the first aperture 11, the second aperture 12, and the first reflector 13 can be adjusted, for example, driven by a motor or manually actuated.

[0078] When the second reflector 13 is introduced, it can also be moved to an appropriate position on the predetermined optical path of the measuring device by motor drive or manual actuation, so that the standard light reflected by the second reflector can pass through the first aperture and the second aperture in sequence and be incident on the first reflector, and so that the standard light reflected by the first reflector can return to pass through the second aperture and the first aperture in sequence, thereby confirming that the optical axis of the standard light source is consistent with the optical axis of the testing device.

[0079] In some embodiments, the first aperture is a variable aperture or a pinhole, and the second aperture is a variable aperture or a pinhole. When the first and second apertures are variable apertures, the aperture of the variable aperture can be reduced by motor drive or manual actuation.

[0080] While the invention has been detailed and described in the accompanying drawings and foregoing description, these descriptions and descriptions should be considered illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments will be understood and practiced by those skilled in the art in practicing the claimed invention through study of the drawings, disclosure, and appended claims.

[0081] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation that may be implemented by the devices and methods according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent one or more modules, one or more devices, or one or more steps. In some cases, the steps of two consecutive blocks may be performed substantially in parallel, and they may sometimes be performed in reverse order, depending on the functionality involved. Furthermore, the flowcharts described above are merely examples. Although the steps of a method are described in a specific order in the specification, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result; rather, the order in which the steps are performed may be changed. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0082] In the claims, the word "comprising" does not exclude other elements, and the indefinite articles "a" or "an" do not exclude a plurality. A single element or other unit may fulfill the function of multiple items set forth in the claims. The mere fact that certain features are recited only in dissimilar embodiments or dependent claims does not imply that combinations of these features cannot be used advantageously. Without departing from the spirit and scope of this application, the scope of protection of this application covers any possible combination of the various features recited in the various embodiments or dependent claims.

[0083] Any reference marks in the claims should not be construed as limiting the scope of the invention.

Claims

1. A method of online calibration of a spectrometer (8), wherein the spectrometer (8) is in a predetermined light path of a measuring device (20) for analyzing a property of light from the predetermined light path, characterized in that, The method comprises: placing a first diaphragm (11), a second diaphragm (12) and a first mirror (13) in the predetermined optical path to the spectrometer (8); adjusting at least one of the first diaphragm (11), the second diaphragm (12) and the first mirror (13) so that light from a primary light source (1) of the measuring device (20) travelling along the predetermined optical path can pass through the first diaphragm (11) and the second diaphragm (12) in turn and be incident on the first mirror (13), and so that reflected light from the first mirror (13) can pass back through the second diaphragm (12) and the first diaphragm (11) in turn, to thereby determine an optical axis of the predetermined optical path; introducing standard light emitted by a standard light source (9) located outside the predetermined optical path into the predetermined optical path using a second mirror (10) for emission along the determined optical axis towards the spectrometer (8), comprising: placing the second mirror (10) in the predetermined optical path to reflect standard light emitted by the standard light source (9) into the predetermined optical path; adjusting the second mirror (10) and / or the standard light source (9) so that the standard light reflected via the second mirror (10) can pass through the first diaphragm (11) and the second diaphragm (12) in turn and be incident on the first mirror (13), and so that the standard light reflected via the first mirror (13) can pass back through the second diaphragm (12) and the first diaphragm (11) in turn, to thereby ensure that an optical axis of a light beam of the standard light source (9) reflected by the second mirror (10) coincides with an optical axis of a light beam of the predetermined optical path; and calibrating the spectrometer (8) using the standard light.

2. The online calibration method according to claim 1, wherein introducing standard light emitted by a standard light source (9) located outside the predetermined optical path into the predetermined optical path using a second mirror (10) for emission along the determined optical axis towards the spectrometer (8) further comprises: removing the first mirror (13) from the predetermined optical path so that the standard light exiting from the standard light source (9) enters the spectrometer (8) along the determined optical axis.

3. The online calibration method according to any one of claims 1-2, wherein the step of placing a first diaphragm (11), a second diaphragm (12) and a first mirror (13) in the predetermined optical path to the spectrometer (8) comprises any one of: placing the first diaphragm (11) and the second diaphragm (12) in an incident light path on the predetermined optical path before the incident to a sample; or placing the first diaphragm (11) and the second diaphragm (12) in a receiving light path on the predetermined optical path for receiving light exiting from a sample.

4. The on-line calibration method according to any one of claims 1-2, wherein placing a first diaphragm (11), a second diaphragm (12) and a first mirror (13) on the predetermined optical path to the spectrometer (8) comprises: placing the first mirror (13) on the predetermined optical path in a receiving optical path for receiving light exiting from a sample and adjacent to the spectrometer (8).

5. The on-line calibration method according to claim 2, wherein placing a second mirror (10) on the predetermined optical path comprises any one of: placing the second mirror (10) on the predetermined optical path in an incident optical path before incidence to a sample; or placing the second mirror (10) on the predetermined optical path in a receiving optical path for receiving light exiting from the sample.

6. The on-line calibration method according to any one of claims 1-2, wherein the first diaphragm (11) is a variable diaphragm or a pinhole, and the second diaphragm (12) is a variable diaphragm or a pinhole.

7. The on-line calibration method according to claim 6, wherein in the case that both the first diaphragm (11) and the second diaphragm (12) are variable diaphragms, the adjusting at least one of the first diaphragm (11), the second diaphragm (12) and the first mirror (13) comprises: reducing the aperture of both the first diaphragm (11) and the second diaphragm (12) to a respective set predetermined value; and such that light of a main light source (1) of the measuring device (20) is still able to pass through the reduced aperture of both the first diaphragm (11) and the second diaphragm (12), and the reflected light via the first mirror (13) is still able to return through the first diaphragm (11) and the second diaphragm (12) to thereby determine an optical axis of the predetermined optical path.

8. The on-line calibration method according to any one of claims 1-2, wherein the spectrometer (8) is part of the measuring device (20), or exists as a receiver outside the measuring device (20).

9. The on-line calibration method according to any one of claims 1-2, wherein the measuring device (20) is a film thickness measuring device (20).

10. An on-line calibration apparatus of a spectrometer (8) for on-line calibration of a spectrometer (8) on a predetermined optical path of a measuring device (20), the on-line calibration apparatus comprising at least: a first diaphragm (11) and a second diaphragm (12) placed on the predetermined optical path to the spectrometer (8); and a first mirror (13) placed on the predetermined optical path in a receiving optical path for receiving light exiting from a sample and adjacent to the spectrometer (8). a first aperture (11), a second aperture (12) and a first mirror (13) movable configured to be operatively movable to appropriate positions on the predetermined optical path to the spectrometer (8) of the measuring device (20) when performing an online calibration, such that light from a primary light source (1) of the measuring device (20) travelling along the predetermined optical path is able to pass through the first aperture (11) and the second aperture (12) in turn and be incident on the first mirror (13), and such that reflected light from the first mirror (13) is able to pass through the second aperture (12) and the first aperture (11) in turn, thereby determining an optical axis of the predetermined optical path; a standard light source (9) arranged outside the predetermined optical path and configured to emit standard light for calibrating the spectrometer (8); a second mirror (10) movable configured to be operatively introduce the standard light into the predetermined optical path when performing an online calibration, to be emitted along the determined optical axis towards the spectrometer (8), thereby enabling calibration of the spectrometer (8); wherein the second mirror (10) is further configured to be operatively moved onto the predetermined optical path such that the standard light reflected via the second mirror (10) is able to pass through the first aperture (11) and the second aperture (12) in turn and be incident on the first mirror (13), and such that the standard light reflected via the first mirror (13) is able to pass back through the second aperture (12) and the first aperture (11) in turn, to thereby determine that an optical axis of a light beam of the standard light source (9) reflected via the second mirror (10) coincides with an optical axis of a light beam of the predetermined optical path.

11. The online calibration device according to claim 10, wherein the first aperture (11) is a variable aperture or a pinhole, the second aperture (12) is a variable aperture or a pinhole, and the first mirror (13) is a plane mirror.

12. The online calibration device according to claim 10 or 11, wherein the spectrometer (8) is part of the measuring device (20) or is present as a receiver outside the measuring device (20).

13. A measuring device (20) comprising the online calibration device according to any one of claims 10-12, to thereby enable online calibration of the measuring device (20).

14. The measuring device (20) according to claim 13, the measuring device (20) being a film thickness measuring device (20).

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