Optical measuring head capable of measuring MEMS high aspect ratio array structure

Abstract

The invention provides an optical measuring head capable of measuring an MEMS high aspect ratio array structure, and relates to the field of MEMS microstructure measurement. The optical measuring head comprises an optical fiber input optical path used for receiving measuring light input from an optical fiber input interface and transmitting the measuring light to a beam combining device; the illumination light path is used for receiving illumination light input from the illumination light source interface and transmitting the illumination light to the beam combining device; the beam combining device is used for combining the measuring light and the illuminating light to obtain combined light; the first measuring light path is used for transmitting the combined beam light to an objective lens interface through a first light splitting flat plate so as to irradiate a measuring sample through an objective lens connected with the objective lens interface; the measuring light path is also used for acquiring reflected light of the measuring sample from the objective lens through the objective lens interface; and the second measuring light path is used for splitting the reflected light into first reflected light and second reflected light, transmitting the first reflected light to the optical fiber output interface and transmitting the second reflected light to the camera interface.

Description

Technical Field

[0001] The present disclosure relates to the field of MEMS microstructure measurement, and more specifically, to an optical probe capable of measuring a MEMS high aspect ratio array structure. Background Art

[0002] With the continuous development of silicon semiconductor manufacturing technology, micro-electromechanical systems (MEMS) have been widely used in the semiconductor field with advantages such as micro size, high performance and low power consumption. Microgrooves are a typical microstructure in MEMS devices, which construct channels, grooves, holes and other structures on silicon wafers to achieve specific functions or requirements in different fields. The microgroove structure has a larger surface area and longitudinal space, which can significantly improve the contact area of ​​the medium, the charge storage capacity of the device, the transmission speed of the signal, and enhance the sensitivity and working efficiency of the device, which is of great significance to the development of semiconductor devices.

[0003] Since it is necessary to determine whether the processed microstructure meets the requirements, it is of great significance to provide an optical non-destructive measurement method for MEMS high aspect ratio array microstructures.

[0004] At present, the measurement of characteristic parameters of MEMS microgroove periodic structure still uses scanning electron microscope (SEM), atomic force microscope (AFM), electronic computer tomography (CT) and other methods. Scanning electron microscope technology will damage the experimental samples and the operation is complicated and time-consuming. The measurement range of atomic force microscope technology is limited by the size of the probe. The cost of electronic computer tomography is high and the efficiency is low. When measuring MEMS high aspect ratio array structures, other existing optical measurement methods have low light return efficiency due to the high aspect ratio characteristics of the structure to be measured, and the measurement effect is not ideal. Summary of the invention

[0005] In view of the above technical problems, the present disclosure provides an optical probe capable of measuring a MEMS high aspect ratio array structure, so as to achieve non-destructive measurement of the MEMS high aspect ratio array structure.

[0006] According to a first aspect of the present disclosure, an optical probe capable of measuring a MEMS high aspect ratio array structure is provided, comprising: an optical fiber input optical path for receiving measurement light input from an optical fiber input interface and transmitting the measurement light to a beam combining device; an illumination optical path for receiving illumination light input from an illumination light source interface and transmitting the illumination light to the beam combining device; a beam combining device for combining the measurement light and the illumination light to obtain combined light; a first measurement optical path for transmitting the combined light to an objective lens interface through a first beam splitter plate, so as to transmit the combined light to a measurement sample through an objective lens connected to the objective lens interface; and the measurement optical path is also used to obtain reflected light of the measurement sample from the objective lens through the objective lens interface; a second measurement optical path for splitting the reflected light into a first reflected light and a second reflected light, and transmitting the first reflected light to the optical fiber output interface and the second reflected light to the camera interface.

[0007] According to an embodiment of the present disclosure, the fiber optic input optical path includes: a fiber optic collimation component for collimating the received measurement light; a first adjustable aperture for limiting the beam diameter of the collimated measurement light within a predetermined range, and transmitting the measurement light with limited beam diameter to a beam combining device to limit the incident numerical aperture range when the measurement light converges and irradiates the sample; wherein the predetermined range is 1~12mm.

[0008] According to an embodiment of the present disclosure, the numerical aperture of the measurement light input from the optical fiber input interface is limited to 0.22-0.39.

[0009] According to an embodiment of the present disclosure, the illumination light path includes: a second adjustable aperture, used to receive illumination light and limit the divergence angle of the illumination light to reduce stray light generated by the illumination light in the optical probe; an imaging component, used to image the illumination light source to the back focal plane of the objective lens, and then the real image is emitted into the objective lens to form uniform Kohler illumination; a first filter component, used to transmit the illumination light passing through the imaging component to the beam combining device.

[0010] According to an embodiment of the present disclosure, the second measurement optical path includes: a second splitter plate, used to split the reflected light passing through the first splitter plate into a first reflected light and a second reflected light; a spectral measurement sub-optical path, used to transmit the first reflected light to the optical fiber output interface; and a camera measurement sub-optical path, used to transmit the second reflected light to the camera interface.

[0011] According to an embodiment of the present disclosure, the reflected light is reflected by the second beam splitter plate to form the first reflected light, and is transmitted to form the second reflected light.

[0012] According to an embodiment of the present disclosure, the spectral measurement optical path includes: a second filtering component, used to filter and obtain the spectral information carried by the first reflected light; and a fiber coupling component, coupled to the output fiber through the fiber output interface, used to input the filtered first reflected light into a spectrometer connected to the optical probe through the output fiber.

[0013] According to an embodiment of the present disclosure, the camera measurement optical path includes: a tube lens and a reflector, the tube lens is used to image the second reflected light on the target surface of the camera via the reflector, and the camera is connected to the optical probe through a camera interface.

[0014] According to an embodiment of the present disclosure, the first measuring optical path and the second measuring optical path share the first beam splitter plate.

[0015] According to an embodiment of the present disclosure, the beam combining device includes a dichroic mirror.

[0016] In the optical probe of the embodiment of the present disclosure, the beam diameter of the collimated measuring light is adjusted so that the measuring light irradiated into the groove of the measuring sample can maintain a small incident light cone angle. The small incident light cone angle allows the measuring light to fully irradiate the bottom of the groove structure, obtain the reflected light at the bottom of the groove structure, and ensure the light return efficiency of the measuring sample.

[0017] Therefore, the present disclosure overcomes the technical problem of low light return efficiency and unsatisfactory measurement effect caused by the characteristics of the structure to be measured when measuring MEMS high aspect ratio array structures by strictly limiting the numerical aperture of the measurement light incident on the sample.

[0018] In addition, the present disclosure also transmits the illumination light to the surface of the measurement sample through the illumination light path, the beam combining device, the first measurement light path and the objective lens connected to the objective lens interface inside the optical probe to form Kohler illumination, thereby achieving uniform illumination of the measurement sample. By adjusting the brightness of the illumination light source, the measurement sample can be clearly imaged in the camera and there is a good contrast between the illumination light and the measurement light spot, which is convenient for observing the area to be measured and adjusting the irradiation position of the measurement light. By adjusting the divergence angle of the incident illumination light through the illumination light path, the interference of stray light generated by the illumination light inside the optical probe on other optical elements is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0020] Figure 1 The structural block diagram of an optical probe capable of measuring a MEMS high aspect ratio array structure is schematically shown.

[0021] Figure 2 The figure schematically shows the internal optical path structure of an optical probe according to an embodiment of the present disclosure.

[0022] Figure 3 Schematic diagram of internal components of an optical probe according to a preferred embodiment of the present invention.

[0023] Figure 4AThis is a diagram showing the depth measurement results of a groove structure with a width of 2 μm and a depth of 23 μm on measurement sample No. 1 with an aspect ratio of 18:1 according to the first embodiment of the present disclosure.

[0024] Figure 4B This is a diagram showing the depth measurement results of a groove structure with a width of 5 μm and a depth of 52 μm on measurement sample No. 2 with an aspect ratio of 10:1 according to the second embodiment of the present disclosure.

[0025] Figure 4C This is a diagram showing the depth measurement results of a groove structure with a width of 5 μm and a depth of 82 μm on measurement sample No. 3 with an aspect ratio of up to 17:1 according to the third embodiment of the present disclosure.

[0026] Figure 4D This is a diagram showing the depth measurement results of a groove structure with a width of 5 μm and a depth of 138 μm on measurement sample No. 4 with an aspect ratio of 27:1 according to the fourth embodiment of the present disclosure.

[0027] Figure 4E This is a diagram showing the depth measurement results of a groove structure with a width of 2 μm and a depth of 23 μm on measurement sample No. 5 with an aspect ratio of 50:1 according to the fifth embodiment of the present disclosure.

[0028] Figure 4F This is a diagram of the depth measurement results of a groove structure with a width of 10 μm and a depth of 441 μm on the No. 6 ultra-high aspect ratio measurement sample with an aspect ratio of 44:1 according to the sixth embodiment of the present disclosure.

[0029] Figure 5 A line graph of measured data for repeatability analysis of system performance in a preferred embodiment.

[0030] Figure 6 A comparison graph of measurement results and SEM calibration values ​​for accuracy analysis of the system performance of a preferred embodiment.

[0031] Figure 7 It is a linear fitting analysis diagram of the measurement results of a preferred embodiment and the SEM calibration value. DETAILED DESCRIPTION

[0032] Based on the above problems, the embodiments of the present disclosure provide an optical probe capable of measuring MEMS high aspect ratio array structures, thereby ensuring the light return efficiency of the structure to be measured and realizing optical non-destructive measurement of MEMS high aspect ratio micro-array structures.

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0034] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0035] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0036] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0037] Figure 1 The structural block diagram of an optical probe capable of measuring a MEMS high aspect ratio array structure is schematically shown.

[0038] like Figure 1As shown, the optical probe capable of measuring the MEMS high aspect ratio array structure of this embodiment includes an optical fiber input optical path 110, which is used to receive the measurement light input from the optical fiber input interface, and transmit the measurement light with a limited beam diameter to the beam combining device 130. The illumination optical path 120 is used to receive the illumination light input from the illumination light source interface, and transmit the illumination light to the beam combining device 130. The beam combining device 130 is used to combine the measurement light and the illumination light to obtain the combined light. The first measurement optical path 140 is used to transmit the combined light to the objective lens interface 141 through the first beam splitter plate, so as to transmit the combined light to the measurement sample 142 through the objective lens 240 connected to the objective lens interface 141. The first measurement optical path 140 is also used to obtain the reflected light of the measurement sample 142 from the objective lens through the objective lens interface 141. The second measurement optical path 150 is used to split the reflected light into a first reflected light and a second reflected light, and transmit the first reflected light to the optical fiber output interface 152 and the second reflected light to the camera interface 151. When the optical probe is used for measurement, the optical fiber output interface 152 is coupled to the output optical fiber connected to the spectrometer, and the camera interface 151 is connected to the camera.

[0039] According to the embodiments of the present disclosure, by strictly limiting the numerical aperture of the measurement light incident on the sample, a small incident light cone angle is maintained when the measurement light irradiates the groove structure of the measurement sample, thereby obtaining better reflected light return efficiency.

[0040] In one embodiment, the illumination light source may be an LED light source.

[0041] In another embodiment, the light emitting wavelength range of the illumination light source is blue light in the range of 441 nm to 461 nm.

[0042] In yet another embodiment, the illumination light source may be a sheet-shaped LED light source.

[0043] According to an embodiment of the present disclosure, the numerical aperture of the measurement light input from the optical fiber input interface is limited to 0.22-0.39.

[0044] According to an embodiment of the present disclosure, the measuring light is input into the optical probe through an incident optical fiber coupled to the optical fiber input interface, the numerical aperture of the incident optical fiber is limited to 0.22~0.39, and the beam diameter of the collimated measuring light is adjusted by the first adjustable aperture so that the cone angle is kept at a small value when the subsequent measuring light converges to the incident sample, thereby improving the light return rate at the bottom of the groove when the optical probe measures a high aspect ratio groove sample, thereby enhancing the measurement signal of the groove depth.

[0045] According to an embodiment of the present disclosure, the optical fiber input light path includes: an optical fiber collimation assembly for collimating the received measurement light; a first adjustable aperture for limiting the beam diameter of the collimated measurement light within a predetermined range, and transmitting the input light with limited beam diameter to the beam combining device; wherein the predetermined range is 1~12mm.

[0046] According to an embodiment of the present disclosure, the optical fiber input optical path includes an optical fiber collimation component to collimate the received measurement light. The measurement light is coupled to the optical fiber input interface via the incident optical fiber and injected into the optical fiber input optical path. The measurement light injected via the incident optical fiber may have a large divergence angle, resulting in the measurement light beam energy not being concentrated. Therefore, the incident measurement light is collimated by the optical fiber collimation component to make the measurement light energy more concentrated.

[0047] According to an embodiment of the present disclosure, the first adjustable aperture receives the measurement light collimated by the fiber collimation assembly. The predetermined range of the beam diameter restriction of the measurement light by the first adjustable aperture is 1 to 12 mm. By adjusting the beam diameter of the collimated measurement light, the numerical aperture of the measurement light incident on the MEMS high aspect ratio array groove structure is further controlled. By collimating the measurement light, limiting the beam diameter, and further performing numerical aperture restriction, the measurement light is made to illuminate the MEMS high aspect ratio array groove structure with an incident light cone angle as small as possible, thereby avoiding stray light generated by multiple reflections of the measurement light, thereby avoiding the interference of stray light on the measurement signal containing the groove information.

[0048] Therefore, in the embodiment of the present disclosure, the incident light cone angle can be ensured to be as small as possible through the optical fiber collimation component and the first adjustable aperture, so that the measurement light can reach the bottom of the groove structure more easily and the reflected light loss of the test sample can be reduced as much as possible, thereby increasing the amount of return light collected from the MEMS high aspect ratio array groove structure. According to the embodiment of the present disclosure, the illumination light path includes a second adjustable aperture for receiving illumination light and limiting the divergence angle of the illumination light to reduce the stray light generated by the illumination light in the optical probe; an imaging component for imaging the illumination light source to the back focal plane of the objective lens; and a first filter component for transmitting the illumination light passing through the imaging component to the beam combining device.

[0049] According to an embodiment of the present disclosure, the second adjustable iris is used to receive the illumination light and limit the divergence angle of the illumination light. Illumination light with a large divergence angle entering the interior of the optical probe will cause the scattered illumination light to be distributed in too many areas of the optical probe, which may easily generate stray light entering the camera or spectrometer. Therefore, by controlling the divergence angle of the incident illumination light through the second adjustable iris, the generation of stray light inside the optical probe is effectively controlled, and the interference of stray light on measurement is reduced.

[0050] According to an embodiment of the present disclosure, the illumination light path further includes an imaging component. The imaging component is used to form a real image of the illumination light source on the back focal plane of the objective lens. The illumination light source is imaged on the back focal plane of the objective lens by the imaging component, so that when the illumination light passes through the objective lens and irradiates the measurement sample, Kohler illumination is formed in the measured area of ​​the measurement sample.

[0051] According to the embodiment of the present disclosure, the illumination light path also includes a first filter component, which is used to transmit the illumination light passing through the imaging component to the beam combining device. The first filter component is also used to filter the illumination light irradiated into the first filter component through the imaging device, and filter out the illumination light with overlapping or similar frequency to the measurement light, so as to prevent the illumination light with the same frequency as the measurement light from interfering with the measurement spectrum received by the spectrometer.

[0052] According to an embodiment of the present disclosure, the illumination light is filtered by the first filter component and then transmitted to the beam combining device to be combined with the measurement light also transmitted to the beam combining device.

[0053] According to an embodiment of the present disclosure, in the process of combining the illumination light and the measurement light via the beam combining device, the illumination light is reflected and the measurement light is transmitted.

[0054] According to an embodiment of the present disclosure, the second measurement optical path includes: a second splitter plate, used to split the reflected light passing through the first splitter plate into a first reflected light and a second reflected light; a spectral measurement sub-optical path, used to transmit the first reflected light to the optical fiber output interface; and a camera measurement sub-optical path, used to transmit the second reflected light to the camera interface.

[0055] According to an embodiment of the present disclosure, the second beam splitter plate splits the reflected light into a first reflected light and a second reflected light. The first reflected light is sent to a spectrometer for spectral analysis, and the second reflected light is sent to a camera for imaging.

[0056] According to an embodiment of the present disclosure, the splitting ratio of the second splitter plate may be 50:50, and the operating wavelength may be 400 nm to 700 nm.

[0057] According to an embodiment of the present disclosure, the reflected light is reflected by the second beam splitter plate to form the first reflected light, and is transmitted to form the second reflected light.

[0058] According to an embodiment of the present disclosure, the spectral measurement optical path includes: a second filtering component, used to filter and obtain the spectral information carried by the first reflected light; and a fiber coupling component, coupled to the output fiber through the fiber output interface, used to input the filtered first reflected light into a spectrometer connected to the optical probe through the output fiber.

[0059] According to the embodiments of the present disclosure, the illumination light contained in the first reflected light can be filtered out by the second filter component, thereby preventing the illumination light from interfering with the spectral analysis.

[0060] According to an embodiment of the present disclosure, the optical fiber coupling assembly is used to input the filtered first reflected light into a spectrometer connected to an optical probe through an output optical fiber for analysis.

[0061] According to an embodiment of the present disclosure, the camera measurement optical path includes: a tube lens and a reflector, the tube lens is used to image the second reflected light on the target surface of the camera via the reflector, and the camera is connected to the optical probe through a camera interface.

[0062] According to an embodiment of the present disclosure, the first measuring optical path and the second measuring optical path share the first beam splitter plate.

[0063] According to an embodiment of the present disclosure, the beam combining device includes a dichroic mirror.

[0064] Figure 2 The figure schematically shows the internal optical path structure of an optical probe according to an embodiment of the present disclosure.

[0065] like Figure 2 As shown, the incident optical fiber 270 is coupled to the optical fiber input interface 111, and the measurement light output by the incident optical fiber 270 can be transmitted to the inside of the optical probe through the optical fiber input interface 111. The measurement light (numerical aperture limited) passing through the optical fiber input interface 111 passes through the optical fiber collimation component 210 and the first adjustable aperture 211 in sequence. The optical fiber collimation component 210 collimates the received measurement light, and the first adjustable aperture 211 is used to limit the beam diameter of the collimated measurement light within a predetermined range, and transmit the measurement light with limited beam diameter to the beam combining device 130.

[0066] According to an embodiment of the present disclosure, the optical fiber collimation assembly 210 may be a collimator. The incident optical fiber may be a multimode optical fiber with a numerical aperture range of 0.22 to 0.39. The first adjustable aperture 211 may be a lever-adjustable aperture.

[0067] According to an embodiment of the present disclosure, the illumination optical path includes a second adjustable diaphragm 221, an imaging component 222, and a first filter component 223. The second adjustable diaphragm 221 receives the illumination light incident from the illumination light source interface 220 and limits the divergence angle of the illumination light, and the illumination light may be generated by a light source connected to the illumination light source interface 220. The imaging component 222 receives the illumination light passing through the second adjustable diaphragm 221, and images the real image of the light source on the back focal plane 241 of the objective lens. The first filter component 223 receives the illumination light emitted from the imaging component 222, filters the illumination light so that the wavelength range of the illumination light and the measurement light do not overlap, and sends the illumination light to the beam combining device 130.

[0068] According to an embodiment of the present disclosure, the second adjustable aperture 221 may be a ring-driven adjustable aperture.

[0069] According to an embodiment of the present disclosure, the beam combining device 130 combines the measuring light with the illumination light to form a combined light beam, wherein the illumination light is reflected and the measuring light is transmitted.

[0070] According to an embodiment of the present disclosure, the beam combining device 130 may be a dichroic mirror.

[0071] According to an embodiment of the present disclosure, the dichroic mirror may be a long-wave pass mirror.

[0072] According to an embodiment of the present disclosure, the transmission band of the dichroic mirror may be 505 nm to 800 nm, and the reflection band may be 380 nm to 475 nm.

[0073] According to an embodiment of the present disclosure, the combined light beam is transmitted to the objective lens 240 connected to the objective lens interface 141 via the first beam splitter plate 241 in the first measurement sub-optical path. The objective lens 240 transmits the combined light beam to the measurement sample 142; the first measurement optical path 140 is also used to obtain the reflected light of the measurement sample 142 from the objective lens 240 through the objective lens interface 141; the combined light beam and the reflected light share the same objective lens and the first measurement optical path, ensuring the system consistency of the measurement optical path.

[0074] According to an embodiment of the present disclosure, the reflected light returned by the objective lens 240 transmits through the first beam splitter plate 241 of the first measuring sub-optical path and is transmitted to the second measuring optical path.

[0075] According to an embodiment of the present disclosure, the splitting ratio of the first splitter plate 241 may be 50:50, and the operating wavelength may be 400 nm to 700 nm.

[0076] According to an embodiment of the present disclosure, the second measuring optical path includes a second beam splitter plate 250 for splitting the reflected light passing through the first beam splitter plate 241 into a first reflected light and a second reflected light. The second beam splitter plate 250 may have a beam splitting ratio of 50:50 and an operating wavelength of 400nm to 700nm.

[0077] The reflected light is reflected by the second beam splitter plate 250 to form the first reflected light, and is transmitted by the second beam splitter plate 250 to form the second reflected light. The first reflected light enters the spectrum measurement sub-light path, and the second reflected light enters the camera measurement sub-light path.

[0078] The spectrum measurement sub-optical path includes: a second filter component 253 and a fiber coupling component 254. The second filter component 253 filters the incident first reflected light and blocks the illumination light from the spectrum measurement sub-optical path. The fiber coupling component 254 is coupled to the output fiber 260 through the fiber output interface 152, and inputs the filtered first reflected light through the output fiber 260 to the spectrometer connected to the optical probe for analysis.

[0079] The camera measurement sub-optical path includes: a tube lens 251 and a reflector 252. The tube lens 251 images the second reflected light on the target surface of the camera via the reflector 252. The camera is connected to the optical probe via the camera interface 151.

[0080] Figure 3 Schematic diagram of internal components of an optical probe according to a preferred embodiment of the present invention.

[0081] like Figure 3 As shown, the measuring light is input into the optical probe through the optical fiber input interface 1, and then passes through the collimator 6 and the lever adjustable aperture 7 to reach the dichroic mirror 8 to combine with the illumination light to form a combined light. The illumination light is emitted by the LED illumination light source 4, and then passes through the ring-driven adjustable aperture 9, the imaging mirror 10, and the bandpass filter 11 to reach the dichroic mirror 8 to combine with the measuring light to form a combined light.

[0082] The combined light is reflected by the first beam splitter plate 12 and enters the objective lens 5 to illuminate the measurement sample. The reflected light of the measurement sample enters the optical probe through the objective lens 5, and reaches the second beam splitter plate 13 through the transmission of the first beam splitter plate 12. The reflected light is reflected by the second beam splitter plate 13 to form the first reflected light, and is transmitted by the second beam splitter plate 13 to form the second reflected light. The first reflected light passes through the long-wave filter 16, the fiber coupling mirror 17, and the fiber output interface 2 in sequence, and is output by the optical probe and enters the spectrometer for spectral analysis. The second reflected light passes through the tube lens 14 and the reflector 15 in sequence to enter the camera 3 for imaging.

[0083] Figure 4A to Figure 4F Shows the use of Figure 3 The experimental results of the optical probe measuring the groove depth of the MEMS high aspect ratio array structure measurement samples with different aspect ratios. Each figure includes three parts (a), (b) and (c). Part (a) is the microscopic image of the measurement area of ​​the high aspect ratio sample formed by the camera when the measurement light irradiation position is adjusted, in which the circular spot is the measurement light spot; Part (b) is the measurement profile obtained by measuring the measurement sample using a cross-section SEM (scanning electron microscope); The left side of part (c) is the result analysis diagram obtained by performing spectral analysis and FFT analysis on the reflected light of the measurement sample in the spectrometer; the right side is the microscopic image of the measurement area presented by the reflected light of the above measurement sample in the camera.

[0084] Figure 4A This is a diagram showing the depth measurement results of a groove structure with a width of 2 μm and a depth of 23 μm on measurement sample No. 1 with an aspect ratio of 18:1 according to the first embodiment of the present disclosure.

[0085] In the figure (c), the analysis wavelength range of the spectrometer is 550-749 mm, the measurement range is 0-260 μm, the integration time is 500000 μs, the measurement resolution is 1.038 μm, the measurement result is 23.295 μm, and the standard deviation is 0.022 μm.

[0086] The following table 1 is for Figure 4A The corresponding statistics of the groove depth measurement results at multiple points of measurement sample No. 1. The width and depth are the calibrated width value and depth value of each groove on the measurement sample measured by cross-section SEM, respectively; the groove width and spacing in the design dimensions are the design values ​​of the groove width and groove spacing determined when designing the MEMS high aspect ratio array structure; the aspect ratio is the ratio of the depth calibration value to the width calibration value. The groove depth measurement value is the groove depth value measured in this preferred embodiment. The units of the above values ​​are all μm. The deviation from the SEM value refers to the deviation percentage between the groove depth measurement value and the depth calibration value measured by cross-section SEM.

[0087] Table 1

[0088]

[0089] refer to Figure 4A As can be seen from the data in Table 1 above, the preferred embodiment of the optical probe measures a MEMS high aspect ratio array structure in a depth range of 19.4 to 24.5 μm, and the aspect ratio can reach 18:1.

[0090] Figure 4B This is a diagram showing the depth measurement results of a groove structure with a width of 5 μm and a depth of 52 μm on measurement sample No. 2 with an aspect ratio of 10:1 according to the second embodiment of the present disclosure.

[0091] In the figure (c), the analysis wavelength range of the spectrometer is 550-749 mm, the measurement range is 0-260 μm, the integration time is 100000 μs, the measurement resolution is 1.038 μm, the measurement result is 52.114 μm, and the standard deviation is 0.032 μm.

[0092] The following table 2 is for Figure 4B The corresponding statistics of the multi-point groove depth measurement results of the measurement sample No. 2. The width and depth are the calibrated width value and depth value of each groove on the measurement sample measured by cross-section SEM, respectively; the groove width and spacing in the design dimensions are the design values ​​of the groove width and groove spacing determined when designing the MEMS high aspect ratio array structure; the aspect ratio is the ratio of the depth calibration value to the width calibration value. The groove depth measurement value is the groove depth value measured in this preferred embodiment. The units of the above values ​​are all μm. The deviation from the SEM value refers to the deviation percentage between the groove depth measurement value and the depth calibration value measured by cross-section SEM.

[0093] Table 2

[0094]

[0095] refer to Figure 4B As can be seen from the data in Table 2 above, the preferred embodiment of the optical probe measures a MEMS high aspect ratio array structure in a depth range of 52.3 to 53.4 μm, and the aspect ratio can reach 10:1.

[0096] Figure 4C This is a diagram showing the depth measurement results of a groove structure with a width of 5 μm and a depth of 82 μm on measurement sample No. 3 with an aspect ratio of up to 17:1 according to the third embodiment of the present disclosure.

[0097] In the figure (c), the analysis wavelength range of the spectrometer is 550-749 mm, the measurement range is 0-260 μm, the integration time is 100000 μs, the measurement resolution is 1.038 μm, the measurement result is 82.391 μm, and the standard deviation is 0.026 μm.

[0098] The following table 3 is for Figure 4C The corresponding statistics of the multi-point groove depth measurement results of the measurement sample No. 3. The width and depth are the calibrated width value and depth value of each groove on the measurement sample measured by cross-section SEM, respectively; the groove width and spacing in the design dimensions are the design values ​​of the groove width and groove spacing determined when designing the MEMS high aspect ratio array structure; the aspect ratio is the ratio of the depth calibration value to the width calibration value. The groove depth measurement value is the groove depth value measured in this preferred embodiment. The units of the above values ​​are all μm. The deviation from the SEM value refers to the deviation percentage between the groove depth measurement value and the depth calibration value measured by cross-section SEM.

[0099] Table 3

[0100]

[0101] refer to Figure 4C As can be seen from the data in Table 3 above, the preferred embodiment of the optical probe measures a MEMS high aspect ratio array structure in a depth range of 83.7 to 85.1 μm, and the aspect ratio can reach 17:1.

[0102] Figure 4D This is a diagram showing the depth measurement results of a groove structure with a width of 5 μm and a depth of 138 μm on measurement sample No. 4 with an aspect ratio of 27:1 according to the fourth embodiment of the present disclosure.

[0103] In the figure (c), the analysis wavelength range of the spectrometer is 550-749 mm, the measurement range is 0-260 μm, the integration time is 100000 μs, the measurement resolution is 1.038 μm, the measurement result is 138.453 μm, and the standard deviation is 0.051 μm.

[0104] The following table 4 is for Figure 4D The corresponding statistics of the multi-point groove depth measurement results of measurement sample No. 4. The width and depth are the calibrated width value and depth value of each groove on the measurement sample measured by cross-section SEM, respectively; the groove width and spacing in the design dimensions are the design values ​​of the groove width and groove spacing determined when designing the MEMS high aspect ratio array structure; the aspect ratio is the ratio of the depth calibration value to the width calibration value. The groove depth measurement value is the groove depth value measured in this preferred embodiment. The units of the above values ​​are all μm. The deviation from the SEM value refers to the deviation percentage between the groove depth measurement value and the depth calibration value measured by cross-section SEM.

[0105] Table 4

[0106]

[0107] refer to Figure 4D As can be seen from the data in Table 4 above, the preferred embodiment of the optical probe covers a depth range of 141 to 143 μm for measuring MEMS high aspect ratio array structures, and the aspect ratio index can reach 27:1.

[0108] Figure 4E This is a diagram showing the depth measurement results of a groove structure with a width of 5 μm and a depth of 251 μm on measurement sample No. 5 with an aspect ratio of 50:1 according to the fifth embodiment of the present disclosure.

[0109] In the figure (c), the analysis wavelength range of the spectrometer is 550-749 mm, the measurement range is 10-500 μm, the integration time is 500000 μs, the measurement resolution is 1.038 μm, the measurement result is 251.410 μm, and the standard deviation is 0.035 μm.

[0110] The following table 5 is for Figure 4E The corresponding statistics of the multi-point groove depth measurement results of measurement sample No. 5. The width and depth are the calibrated width value and depth value of each groove on the measurement sample measured by cross-section SEM, respectively; the groove width and spacing in the design dimensions are the design values ​​of the groove width and groove spacing determined when designing the MEMS high aspect ratio array structure; the aspect ratio is the ratio of the depth calibration value to the width calibration value. The groove depth measurement value is the groove depth value measured in this preferred embodiment. The units of the above values ​​are all μm. The deviation from the SEM value refers to the deviation percentage between the groove depth measurement value and the depth calibration value measured by cross-section SEM.

[0111] Table 5

[0112]

[0113] refer to Figure 4EAs can be seen from the data in Table 5 above, the aspect ratio index of the preferred embodiment of the optical probe for measuring the MEMS high aspect ratio array structure can reach 50:1.

[0114] Figure 4F This is a diagram of the depth measurement results of a groove structure with a width of 10 μm and a depth of 441 μm on the No. 6 ultra-high aspect ratio measurement sample with an aspect ratio of 44:1 according to the sixth embodiment of the present disclosure.

[0115] In the figure (c), the analysis wavelength range of the spectrometer is 550-740 mm, the measurement range is 20-700 μm, the integration time is 500,000 μs, the measurement resolution is 1.071 μm, the measurement result is 440.695 μm, and the standard deviation is 0.068 μm.

[0116] The following table 6 is for Figure 4F The corresponding statistics of the multi-point groove depth measurement results of measurement sample No. 6. The width and depth are the calibrated width value and depth value of each groove on the measurement sample measured by cross-section SEM, respectively; the groove width and spacing in the design dimensions are the design values ​​of the groove width and groove spacing determined when designing the MEMS high aspect ratio array structure; the aspect ratio is the ratio of the depth calibration value to the width calibration value. The groove depth measurement value is the groove depth value measured in this preferred embodiment. The units of the above values ​​are all μm. The deviation from the SEM value refers to the deviation percentage between the groove depth measurement value and the depth calibration value measured by cross-section SEM.

[0117] Table 6

[0118]

[0119] refer to Figure 4F As can be seen from the data in Table 6 above, the aspect ratio index of the preferred embodiment of the optical probe for measuring the MEMS high aspect ratio array structure can reach 44:1.

[0120] Figure 5 A line graph of measured data for repeatability analysis of system performance in a preferred embodiment.

[0121] The horizontal axis is the number of measurements, and the vertical axis is the measurement result / μm. Considering the influence of light source intensity fluctuation and external factors on the measurement results, the experimental sample is measured 10 times and the average is taken as the final measurement result. In the process of repeated measurement, the measurement conditions must be the same.

[0122] Table 7 below shows the data of repeated measurements of some experimental samples, and the relative standard deviation (RSD) is calculated. Among them, the SEM value is used as the calibration value.

[0123] Table 7

[0124]

[0125] The depth range of the experimental samples is about 20 to 440 μm. Through analysis, it can be seen that under the same measurement conditions, the fluctuation range of the measurement results is in the nanometer level, and the RSD values ​​are better than 0.1%, which proves that the measurement results of this preferred embodiment are relatively stable and have good repeatability.

[0126] Figure 6 A comparison graph of measurement results and SEM calibration values ​​for accuracy analysis of the system performance of a preferred embodiment.

[0127] Table 8 below shows the comparison and deviation between the SEM calibration values ​​and the measurement results of some experimental samples. Analysis shows that the deviation between the measurement results of the preferred embodiment and the SEM calibration values ​​is generally better than 3%.

[0128] Table 8

[0129]

[0130] Figure 7 The figure is a linear fitting analysis diagram of the measurement results of a preferred embodiment and the SEM calibration value. The linear fitting analysis of the measurement results of the preferred embodiment and the SEM calibration value shows that the linear correlation coefficient is better than 0.9994 through calculation, which proves that the depth measurement results of the preferred embodiment and the SEM calibration value have good linearity.

[0131] By using the optical probe capable of measuring the MEMS high aspect ratio array structure according to the embodiment of the present disclosure, accurate optical non-destructive measurement of the groove depth of the high aspect ratio array structure can be achieved. The collimation of the measuring light is adjusted by using the optical fiber input optical path and the beam diameter of the measuring light is limited. Through collimation and beam diameter limitation, the measuring light can be incident on the groove of the MEMS high aspect ratio array structure at a smaller light cone angle, so that the measuring light can reach the bottom of the groove and generate reflected light to be received by the optical probe. By analyzing the spectral information carried by the reflected light, the depth, width and other internal information of the groove of the high aspect ratio structure are determined. It is difficult for other existing optical measurement methods to measure the depth of structures with an aspect ratio greater than 20:1. The present disclosure can achieve the measurement of MEMS grooves with an aspect ratio higher than 40:1. The embodiment of the present disclosure improves the light return efficiency when the reflective optical measurement technology is applied to the measurement of the MEMS high aspect ratio array structure by controlling the numerical aperture of the measuring light incident on the sample, improves the measurement effect, and achieves non-destructive measurement of the MEMS high aspect ratio array structure.

[0132] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0133] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. An optical probe capable of measuring a MEMS high aspect ratio array structure, characterized in that: The optical probe comprises: The optical fiber input optical path is used to receive the measurement light input from the optical fiber input interface and transmit the measurement light with limited beam diameter to the beam combining device; An illumination light path, used for receiving illumination light input from an illumination light source interface and transmitting the illumination light to the beam combining device; The beam combining device is used to combine the measuring light and the illumination light to obtain a combined light; a first measuring optical path, used to transmit the combined light beam to the objective lens interface through the first beam splitter plate, so as to transmit the combined light beam to the measuring sample through the objective lens connected to the objective lens interface; and the measuring optical path is also used to obtain the reflected light of the measuring sample from the objective lens through the objective lens interface; The second measuring optical path is used to split the reflected light into a first reflected light and a second reflected light, and transmit the first reflected light to the optical fiber output interface and transmit the second reflected light to the camera interface.

2. The optical probe according to claim 1, characterized in that: The optical fiber input optical path comprises: An optical fiber collimation component, used for collimating the received measurement light; A first adjustable diaphragm is used to limit the beam diameter of the collimated measuring light within a predetermined range, and transmit the measuring light with the limited beam diameter to the beam combining device, so as to limit the incident numerical aperture range when the measuring light is converged and irradiated onto the sample; Wherein, the predetermined range is 1~12mm.

3. The optical probe according to claim 2, characterized in that: The numerical aperture of the measurement light input from the fiber input interface is limited to 0.22~0.

39.

4. The optical probe according to claim 1, characterized in that: The illumination light path comprises: a second adjustable aperture, for receiving the illumination light and limiting the divergence angle of the illumination light, so as to reduce stray light generated by the illumination light in the optical probe; An imaging component, used for imaging the illumination light source onto the back focal plane of the objective lens; The first filter component is used to transmit the illumination light passing through the imaging component to the beam combining device.

5. The optical probe according to claim 1, characterized in that: The second measuring optical path comprises: a second beam splitter plate, used for splitting the reflected light passing through the first beam splitter plate into the first reflected light and the second reflected light; A spectrum measurement sub-optical path, used for transmitting the first reflected light to the optical fiber output interface; The camera measurement sub-optical path is used to transmit the second reflected light to the camera interface.

6. The optical probe according to claim 5, characterized in that: The reflected light is reflected by the second beam splitter plate to form the first reflected light, and is transmitted to form the second reflected light.

7. The optical probe according to claim 5, characterized in that: The spectrum measurement optical path comprises: A second filter component, used for filtering to obtain spectral information carried by the first reflected light; The optical fiber coupling component is coupled with the output optical fiber through the optical fiber output interface, and is used to input the filtered first reflected light into the spectrometer connected to the optical probe through the output optical fiber.

8. The optical probe according to claim 5, characterized in that: The camera measurement optical path includes: a tube lens and a reflector, the tube lens is used to image the second reflected light on the target surface of the camera via the reflector, and the camera is connected to the optical probe through the camera interface.

9. The optical probe according to claim 5, characterized in that: The first measuring optical path and the second measuring optical path share the first beam splitter plate.

10. The optical probe according to claim 1, characterized in that: The beam combining device includes a dichroic mirror.

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