Vacuum microcavity interferometer chip and high-sensitivity optical pressure sensor

Abstract

The utility model relates to a vacuum microcavity interferometer chip and a high-sensitivity optical pressure sensor, the vacuum microcavity interferometer chip comprises a first substrate structure, a second substrate structure and a third substrate structure, the lower surface of the first substrate structure is provided with a first reflecting surface; the second substrate structure is arranged between one side, facing the lower surface of the first substrate structure, of the first substrate structure and one side, facing the upper surface of the third substrate structure, of the third substrate structure, the upper surface of the second substrate structure is provided with a second reflecting surface opposite to and parallel to the first reflecting surface, and the third substrate structure is provided with an optical through hole; the first substrate structure, the second substrate structure and the third substrate structure are configured to be symmetrical relative to the central axis of the substrate structure. In addition, the utility model also provides a high-sensitivity optical pressure sensor. The vacuum microcavity interferometer chip and the high-sensitivity optical pressure sensor provided by the embodiment of the utility model are high in measurement sensitivity, convenient to use and high in adaptability.

Description

TECHNICAL FIELD

[0001] The present application relates to a sensor in the field of optoelectronic technology, in particular to a vacuum microcavity interferometer chip and a high-sensitivity optical pressure sensor. BACKGROUND

[0002] A pressure sensor is a device or apparatus that can sense the pressure signal of a fluid medium such as gas or liquid, and can convert the pressure signal into an electrical signal or optical signal according to certain rules. The pressure sensor is the most commonly used sensor in industrial practice, and is widely used in water conservancy and hydropower, railway transportation, intelligent building, production automatic control, aerospace, military, petrochemical, oil well, power, ship, machine tool, pipeline and other industrial automatic control environments, and is also increasingly widely used in medical devices, robots and automotive electronics, smart phones, smart home appliances and wearable electronic products in the consumer electronics field.

[0003] The product price of a pressure sensor mainly depends on the applicable use conditions and the long-term maintained measurement accuracy. An industrial-grade pressure sensor that meets 0.01% accuracy in a working temperature range of -55℃ to 85℃ and a pressure sensor that meets 0.1% accuracy in a full temperature range and withstands a temperature of more than 200℃ both cost several thousand yuan or even tens of thousands of yuan.

[0004] Especially in airplanes, nuclear power units, high-voltage power transmission and transformation equipment, semiconductor equipment and process industries, as global competition intensifies, digitization and intelligentization have become the main development path for manufacturing to improve quality and increase efficiency, and higher requirements are placed on the long-term measurement accuracy of pressure sensors and their ability to adapt to harsh environments: existing MEMS silicon resonant pressure sensors and capacitive pressure transmitters both require front-end power supply and do not have dynamic response capability to pulsating pressure signals, making it difficult to implant into industrial equipment to achieve data acquisition throughout the life cycle, and they also do not meet the wide frequency response requirements of sensors for real-time capture of transient abnormal signals before equipment failure for predictive maintenance management; and existing optical fiber pressure sensors that use optical fibers or locally processed optical fiber elements (such as fiber Bragg gratings, fiber F-P interference cavities, etc.) as pressure sensitive elements cannot meet the performance requirements of high-precision and high-sensitivity industrial measurement in terms of normal temperature measurement accuracy and sensitivity, wide temperature range measurement accuracy and sensitivity from low temperature to high temperature, and long-term stability, which are far from the level of imported MEMS silicon resonant pressure sensors and capacitive pressure transmitters. If external mechanical forces are transmitted to the MEMS pressure sensitive chip or the welding and packaging part of the MEMS pressure sensitive chip and the optical fiber during the secondary packaging process, the multi-beam F-P interferometer will be subjected to uneven stress, causing the interference spectrum to deteriorate and causing abnormal changes in the measured value.

[0005] Therefore, the prior art still needs to be improved and enhanced.

[0006] It should be noted that the above introduction to the technical background is only for the convenience of clearly and completely describing the technical solutions of the present application and facilitating the understanding of those skilled in the art. The above technical solutions cannot be considered as known to those skilled in the art merely because they are described in the background section of the present application. Content of the utility model

[0007] In order to solve one or more of the above technical problems, the present disclosure proposes a vacuum microcavity interferometer chip and a high-sensitivity optical pressure sensor comprising the same, which is mainly used for measuring pressure signals of fluid media such as gas and liquid. The vacuum microcavity interferometer chip in some embodiments can achieve the requirement of long-term maintenance of high-precision and high-sensitivity measurement.

[0008] In a first aspect of the present disclosure, a vacuum microcavity interferometer chip is provided, comprising: a first substrate structure, a second substrate structure, and a third substrate structure; the first substrate structure is configured with a first substrate structure upper surface and a first substrate structure lower surface, the first substrate structure upper surface is configured as a membrane-island structure with the upper surface surrounded by the side surface, and the first substrate structure lower surface is provided with a first reflecting surface; the second substrate structure is configured with a second substrate structure upper surface and a second substrate structure lower surface, the second substrate structure is arranged between the first substrate structure on the side facing the first substrate structure lower surface and the third substrate structure on the side facing the third substrate structure upper surface, and the second substrate structure upper surface is configured with a second reflecting surface parallel to the first reflecting surface; the third substrate structure is configured with a third substrate structure upper surface and a third substrate structure lower surface, and the third substrate structure is configured with an optical through hole penetrating through the third substrate structure upper surface and the third substrate structure lower surface; the first substrate structure, the second substrate structure, and the third substrate structure are respectively configured as structures symmetrical with respect to the central axis thereof; the first substrate structure lower surface is arranged to be connected with the second substrate structure upper surface, and the second substrate structure lower surface is arranged to be connected with the third substrate structure upper surface.

[0009] Further, in some embodiments, the lower surface of the first substrate structure is configured as a concave cavity, and an F-P interference cavity is arranged between the concave cavity of the first substrate structure and the upper surface of the second substrate structure; the first reflecting surface is arranged on the lower surface of the first substrate structure in the F-P interference cavity; and a top transmission surface is arranged on the surface of the island of the membrane-island structure.

[0010] Further, in some embodiments, the projection area of the second substrate structure in the transverse direction is greater than the projection area of the first substrate structure in the transverse direction or the projection area of the third substrate structure in the transverse direction.

[0011] Further, in some embodiments, the part of the lower surface of the second substrate structure that laterally exceeds the third substrate structure is arranged to be the lower surface of the second substrate structure.

[0012] Further, in some embodiments, the first substrate structure is configured as a quasi-cylindrical structure, the upper surface of the first substrate structure is configured as a circular frame of a membrane-island structure; the second substrate structure and the third substrate structure are configured as square frames of a quasi-cuboid structure; the first substrate structure, the second substrate structure, and the third substrate structure are arranged to have coincident central axes.

[0013] Further, in some embodiments, the diameter of the circular frame of the first substrate structure is the same as the side length of the square frame of the third substrate structure.

[0014] Further, in some embodiments, the optical via hole is provided with a first flat-bottomed groove on the side circumference close to the upper surface of the third substrate structure.

[0015] Further, in some embodiments, the optical via hole is provided with a second flat-bottomed groove on the side circumference close to the lower surface of the third substrate structure.

[0016] Further, in some embodiments, the lower surface of the second substrate structure is configured with a first transmission surface parallel to the second reflection surface; the central axes of the first reflection surface, the second reflection surface, the first transmission surface, the top transmission surface, and the optical via hole coincide.

[0017] Further, in some embodiments, an air-adsorbing agent film is deposited on the periphery of the second reflection surface.

[0018] Further, in some embodiments, the first substrate structure is arranged to be composed of an SOI silicon wafer, the SOI silicon wafer is a three-layer structure composed of a top layer of silicon, a buried oxygen layer, and a bottom layer of silicon in sequence; the second substrate structure is arranged to be composed of a glass substrate; and the third substrate structure is arranged to be composed of a double-polished silicon wafer.

[0019] In a second aspect of the present disclosure, a high-sensitivity optical pressure sensor is also provided, which includes the vacuum microcavity interferometer chip described above, and a fiber collimator arranged to extend from the lower surface of the third substrate structure into the vacuum microcavity interferometer chip through the optical via hole, and the working end face of the fiber collimator is arranged to face and be parallel to the first transmission surface, and the central axis of the fiber collimator coincides with the central axis of the first transmission surface.

[0020] According to some embodiments described above and below, the present disclosure has the beneficial effects that:

[0021] In some embodiments, by configuring the upper surface of the first substrate structure as a membrane-island structure with the upper surface surrounded by the side surface, and by providing the lower surface of the first substrate structure with the first reflective surface (correspondingly, within the F-P cavity), the membrane-island structure as a whole is located outside the F-P interference cavity, the optical path can be increased by increasing the thickness of the island, the process difficulty and transmittance requirement of depositing an optical antireflection film on the island surface can be reduced, the interference influence of multi-interface reflection on the F-P interference cavity can be better eliminated, and the multi-beam F-P interferometer has more excellent spectral characteristics, thereby reducing the interference of pressure detection; at the same time, by providing the lower surface of the first substrate structure to be connected with the upper surface of the second substrate structure, and providing the lower surface of the second substrate structure to be connected with the upper surface of the third substrate structure, the three-layer substrate has good stress matching characteristics, not only can the optical pressure chip as a whole have extremely low heat output, but also the first substrate structure, the second substrate structure and the third substrate structure are respectively configured as a structure symmetrical with respect to the central axis, and such a balanced symmetrical structure is conducive to achieving high stability of the zero-point output of the optical pressure chip through good stress matching. Further, in some embodiments, by providing the second reflective surface with a getter film deposited thereon around the periphery, the long-term high vacuum of the interference cavity is maintained, the refractive index is constant, and the pressure chip has low-vacuum testing capability. By providing the second substrate structure with a second substrate structure lower surface that laterally protrudes beyond the third substrate structure, the outer dimension of the second substrate structure is made larger than the exposed surface formed by the first substrate structure and the third substrate structure to realize bonding or welding fixation with the sensor housing, and then the first substrate structure and the third substrate structure and the fiber collimator are not connected with the sensor housing by solder or adhesive, so as to improve the spectral quality and stability of the vacuum microcavity interferometer chip and the high-sensitivity optical pressure sensor containing the same. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and other features, advantages, and aspects of embodiments of the present disclosure will become more apparent by describing in detail some embodiments thereof with reference to the attached drawings, in which:

[0023] Figure 1 A diagram of a vacuum microcavity interferometer chip according to an embodiment of the present disclosure is shown;

[0024] Figure 2 Another diagram of a vacuum microcavity interferometer chip according to an embodiment of the present disclosure is shown;

[0025] Figure 3 Top and bottom views of a vacuum microcavity interferometer chip according to an embodiment of the present disclosure are shown;

[0026] Figure 4A diagram of a high-sensitivity optical pressure sensor according to an embodiment of the present disclosure is shown;

[0027] Figure 5 A diagram of a high-sensitivity optical pressure sensor according to an embodiment of the present disclosure is shown; and

[0028] In the various drawings, like or corresponding reference numerals indicate like or corresponding parts, wherein: first base structure 10, second base structure 20, third base structure 30, membrane-island structure 11, first reflective surface 12, top transmissive surface 15, second reflective surface 21, first transmissive surface 22, getter film 23, optical via 31, first flat-bottomed groove 32, second flat-bottomed groove 33, fiber collimator 40, fiber collimator protection glass tube 41, solder 42, vacuum microcavity interferometer chip 100, high-sensitivity optical pressure sensor 1000. DETAILED DESCRIPTION

[0029] Embodiments of the present disclosure will be described in more detail with reference to the drawings. Although certain embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms and should not be interpreted as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly and completely understood. It should be understood that the drawings of the present disclosure are for illustrative purposes only and are not intended to limit the scope of the present disclosure.

[0030] In the description of embodiments of the present disclosure, the term "including" and its conjugates are to be understood as open-ended, i.e., "including but not limited to". The term "based on" is to be understood as "based, at least in part, on". The term "one embodiment" or "an embodiment" are to be understood as "at least one embodiment". The term "first", "second", etc. can refer to different or identical objects. Other explicitly and implicitly recited definitions can also be included below.

[0031] It should be understood that the combination of MEMS chip-level manufacturing technology and optical signal detection technology improves the detection sensitivity of the pressure sensor and the ability to withstand strong electromagnetic interference, wide temperature and high impact vibration in harsh working environment. Since the dynamic detection resolution of the multi-beam F-P interferometer to the cavity length can reach 1pm-10pm, and the dynamic detection resolution of the double-beam F-P interferometer to the cavity length can only reach 100pm-1nm, therefore, by constructing a multi-beam F-P interferometer inside the pressure sensitive chip, the sensitivity of the pressure sensor can be greatly improved. However, the construction of a multi-beam F-P interferometer requires the deposition of optical films to improve the optical reflectivity of the two reflecting surfaces of the F-P interferometer, and the parallelism and cleanliness of the two reflecting surfaces have very high requirements, in order to maintain the laser signal incident into the cavity to form hundreds of reflections between the two reflecting surfaces, and meet the basic conditions of multi-wavelength interference. Limited by the temperature resistance range of the optical film 500℃-600℃, only by using the silicon-glass bonding process in the temperature range of 300℃-400℃, can the optical film of the multi-beam F-P interferometer inside the MEMS chip be kept intact, but the gas released by the silicon-glass bonding will reduce the vacuum degree of the interference cavity inside the multi-beam F-P interferometer and form an unstable refractive index, affecting the low pressure measurement range and zero point stability of the MEMS pressure sensitive chip, and also increasing the temperature coefficient and reducing the measurement repeatability. In order to perform high-precision pressure measurement, such sensors usually need to vacuumize the interior of the F-P optical interference cavity, and the vacuum degree needs to be kept stable. Under normal circumstances, some residual gas will be retained in the cavity during the manufacturing process. Therefore, it is necessary to seal a getter in the vacuum cavity, and activate the getter during the sensor manufacturing process to absorb the residual gas in the F-P optical interference cavity, so as to realize high vacuum inside the pressure sensor.

[0032] In addition, after the MEMS pressure sensitive chip and the optical fiber are coupled and packaged to form a MEMS optical pressure module, it is usually necessary to be secondary packaged and fixed on the pressure sensor shell to realize the isolation and protection of the lead cable from the sealed pressure measurement, module measurement to the lead cable, and become a MEMS optical pressure sensor that can be independently installed and used. If the external mechanical force on the shell is transmitted to the MEMS pressure sensitive chip or the welding and packaging part of the MEMS pressure sensitive chip and the optical fiber during the secondary packaging process, it will cause the multi-beam F-P interferometer to be subjected to uneven stress and cause the interference spectrum to deteriorate, causing abnormal changes in the measured value.

[0033] Therefore, only by starting from the design and implementation scheme of the MEMS optical pressure sensitive chip, and from the packaging scheme of the MEMS optical pressure sensitive chip to the pressure module and the pressure sensor, technological innovation can be carried out, so as to truly improve the sensitivity and temperature drift and zero drift characteristics of the MEMS optical pressure sensor, and meet the requirements of long-term high-precision and high-sensitivity measurement.

[0034] To solve one or more of the above technical problems, or potential problems, the present disclosure proposes a vacuum microcavity interferometer chip and a high-sensitivity optical pressure sensor comprising the same. A more detailed description is given below in conjunction with the accompanying drawings.

[0035] Figure 1 A diagram of a vacuum microcavity interferometer chip according to an embodiment of the present disclosure is shown. In this example embodiment, a vacuum microcavity interferometer chip 100 is shown, which comprises: a first substrate structure 10, a second substrate structure 20, and a third substrate structure 30; the first substrate structure 10 is configured with a first substrate structure upper surface (i.e. paper facing up side) and a first substrate structure lower surface (i.e. paper facing down side), the first substrate structure upper surface is configured as a membrane-island structure 11 surrounded by an upper surface and a side surface, as shown, the top surface of the island of the membrane-island structure can be configured with a top transmission surface 15, while the first substrate structure lower surface is provided with a first reflection surface 12; the second substrate structure 20 is configured with a second substrate structure upper surface (i.e. paper facing up direction) and a second substrate structure lower surface (i.e. paper facing down direction), and the second substrate structure 20 is disposed between the side of the first substrate structure facing the first substrate structure lower surface and the side of the third substrate structure facing the third substrate structure upper surface, the second substrate structure upper surface is configured with a second reflection surface 21 opposite and parallel to the first reflection surface 12; the third substrate structure 30 is configured with a third substrate structure upper surface (i.e. paper facing up direction) and a third substrate structure lower surface (i.e. paper facing down direction), the third substrate structure 30 is configured with an optical through-hole 31 through the third substrate structure upper surface and the third substrate structure lower surface; preferably, the first substrate structure 10, the second substrate structure 20, and the third substrate structure 30 are respectively configured as structures symmetric about a central axis (it should be understood that the first substrate structure 10 is symmetric about a central axis of its paper up-down direction, the second substrate structure 20 is symmetric about a central axis of its paper up-down direction, and the third substrate structure 30 is symmetric about a central axis of its paper up-down direction); as shown, the first substrate structure lower surface is provided to be connected to the second substrate structure upper surface (it should be understood that, as shown in the embodiment, the peripheral frame (side wall) of the first substrate structure 10 on the side facing the first substrate structure lower surface is provided to be connected to the second substrate structure 20 on the side facing the second substrate structure upper surface, and this connection can be a bond between silicon (bottom layer of the first substrate structure 10) and glass (second substrate structure 20), similarly, the second substrate structure 20 on the side facing the second substrate structure lower surface is provided to be connected to the peripheral frame (side wall) of the third substrate structure 30 on the side facing the third substrate structure upper surface, and this connection can be a bond between glass (second substrate structure 20) and silicon (top layer of the third substrate structure 30).

[0036] Further, in some preferred embodiments, the second substrate structure 20 has a larger lateral area than the first substrate structure 10 or the third substrate structure 30. It should be understood that the lateral area refers to the size of the area (dimension) of the plane perpendicular to the central axis. In the illustrated embodiment, the second substrate structure 20 has a larger size than the first substrate structure 10 above and the third substrate structure 30 below, and thus an exposed surface appears, with the side facing the first substrate structure 10 being the upper exposed surface of the second substrate structure and the side facing the third substrate structure 30 being the lower exposed surface of the second substrate structure. The portion of the lower surface of the second substrate structure that laterally exceeds the third substrate structure 30 is configured as the lower exposed surface of the second substrate structure. Thus, the size of the second substrate structure 20 is larger than the exposed surface formed by the first substrate structure 10 and the third substrate structure 30, and thus the bonding or welding of the exposed surface (particularly the lower exposed surface of the second substrate structure) to the sensor housing can achieve isolation and protection of the lead cable from the sealed pressure measurement module, and thus the high-sensitivity optical pressure sensor (e.g., a MEMS optical pressure sensor) can be independently installed and used, so that the zero-point output of the final high-sensitivity optical pressure sensor does not change due to stress on the housing before and after mechanical fastening installation.

[0037] Further, in some embodiments, the first substrate structure 10 is configured as a cylindrical structure, and the upper surface of the first substrate structure is configured as a circular frame film-island structure. The circular frame refers to the bottom surface of the first substrate structure 10 being configured as a circular structure when the first substrate structure is configured as a cylindrical structure. The upper surface of the first substrate structure is configured as a film-island structure (although the island portion is convex, the film-island structure is concave except for the island area), and the lower surface is also configured as a concave area to cooperate with the upper surface of the second substrate structure to form an F-P cavity. The concave area can effectively prevent bonding (fitting) between the lower surface of the first substrate structure around the F-P cavity and the upper surface of the second substrate structure. In addition, it should be understood that the circular frame film-island structure of the first substrate structure 10 is the receiving side for sensing fluid pressure, and thus the circular frame film-island structure can ensure that the deformation of the first substrate structure 10 is uniform in all directions when subjected to fluid pressure, whereas a non-circular frame (e.g., a square, triangular, or diamond frame) film-island structure cannot uniformly transmit fluid pressure to the lower surface of the first substrate structure 10, i.e., the F-P cavity, and thus the high-sensitivity optical pressure sensor cannot achieve high-precision and high-sensitivity measurement.

[0038] Further, in some preferred embodiments, the second substrate structure 20 and the third substrate structure 30 are configured as square-frame-like cuboid structures. And the first substrate structure 10, the second substrate structure 20 and the third substrate structure 30 are arranged with the central axes coinciding. The second substrate structure 20 and the third substrate structure 30 are configured as square-frame-like cuboid structures to facilitate the fastening of the vacuum microcavity interferometer chip 100, especially through square recess structures and the like, so that the vacuum microcavity interferometer chip 100 is not prone to rotation along the central axis. Ensuring that the first substrate structure 10, the second substrate structure 20 and the third substrate structure 30 are arranged with the central axes coinciding can ensure the measurement accuracy and sensitivity of the vacuum microcavity interferometer chip 100 formed thereby. It should be understood that if the first substrate structure 10, the second substrate structure 20 and the third substrate structure 30 do not ensure the central axes coinciding, the optical axis of the entire structure (the spatial optical path through which the laser incident on the vacuum microcavity interferometer chip from the fiber collimator) can not be on the central axis, which can affect the change of the optical axis of the overall structure when subjected to fluid pressure, thereby affecting the measurement accuracy and sensitivity of the vacuum microcavity interferometer chip 100.

[0039] Further, in some embodiments, the diameter of the circular frame of the first substrate structure 10 is the same as the side length of the square frame of the third substrate structure 30. This facilitates the processing to form the first substrate structure 10, the second substrate structure 20 and the third substrate structure 30 with the central axes coinciding, and ensures that the side walls of the first substrate structure 10 and the third substrate structure 30 have a larger projected overlapping area (projected overlapping area on the second substrate structure 20) when the wall thickness is the same, so that the second substrate structure 20 is not easily damaged when the first substrate structure 10 and the third substrate structure 30 are extruded to the second substrate structure 20.

[0040] Further, in some embodiments, the optical through-hole 31 is provided with a first flat-bottomed groove 32 on the side near the upper surface of the third substrate structure; preferably, the area of the first flat-bottomed groove 32 near the lower surface of the second substrate structure is larger than the area of the first transmission surface 22 on the lower surface of the second substrate structure (formed by the coating of the antireflection film), to avoid the influence of the antireflection film on the bonding of the second substrate structure 20 and the third substrate structure 30.

[0041] Further, in some embodiments, the optical through-hole 31 is provided with a second flat-bottomed groove 33 on the side near the lower surface of the third substrate structure; the second flat-bottomed groove 33 is used to provide positioning and shear-resistant support for the solder for fixing the fiber collimator and the glass protection tube.

[0042] Further, in some embodiments, the second substrate structure lower surface is configured with a first transmission surface 22 parallel to the second reflection surface 21; and the first reflection surface 12, the second reflection surface 21, the first transmission surface 22 and the optical through hole 31 central axis coincide. Thus, the precision and sensitivity of the high-sensitivity optical pressure sensor formed are improved.

[0043] Further, in some embodiments, in order to increase the vacuum degree between the F-P cavities, a getter film 23 is deposited around the second reflection surface 21. By setting the getter film 23, the residual gas in the cavity is absorbed to ensure high vacuum in the cavity and reduce the influence of residual gas thermal expansion and contraction on pressure measurement precision and sensitivity. It should be understood that if the second reflection surface 21 is an expanded film with a circular structure on the upper surface of the second substrate structure 20, then the getter film 23 is an annular structure around the second reflection surface 21 (reflection film area) on the upper surface of the second substrate structure 20 but not in contact with the second reflection surface 21 (the reflection film area) (i.e. there is a gap).

[0044] Further, in some embodiments, the first substrate structure 10 is configured by an SOI silicon wafer, which is a three-layer structure of top layer silicon, buried oxygen layer and bottom layer silicon, i.e. a three-layer structure of top layer silicon-buried oxygen layer-bottom layer silicon. The cavity formed by removing the top layer silicon and buried oxygen layer serves as the interference cavity of the F-P interferometer. The lower surface of the bottom layer silicon is patterned to deposit an optical reflection film, which serves as the first reflection surface 12 of the F-P cavity. The upper surface of the bottom layer silicon is processed by etching and KOH etching to form a film-island structure with a frame. The frame and island are thick, the film is thin, the upper surface of the island is the original polished surface of silicon and its thickness is consistent with the thickness of the frame. The first substrate structure as a whole is a cylindrical structure. The frame, island and film deformation structures are made on the pressure receiving side of the F-P interference cavity. The thickness of the single crystal silicon of the film and island can be measured and selectively processed in real time after the three-layer substrate is bonded by silicon-glass-silicon. Further, the second substrate structure 20 is configured by a glass substrate, which is a double-polished glass substrate with a second reflection surface 21 and a first transmission surface 22 (optical anti-reflection film) deposited thereon to form an optical F-P interference cavity. A getter film 23 is deposited around the second reflection surface 21 to improve and maintain the vacuum degree in the F-P cavity. The third substrate structure 30 is configured by a silicon wafer, such as an ultra-flat double-polished silicon wafer. It should be understood that in the illustrated embodiment, the first substrate structure 10 is configured by an SOI silicon wafer, so that the first substrate structure 10 in the illustration shows a similar three-layer structure. As can be seen from the illustration, the film-island structure with a frame is disposed on the top layer silicon. The dark part in the middle of the illustration is the buried oxygen layer, and the bottom layer silicon is connected to the second substrate structure 20.

[0045] In addition, in cooperation with the optical collimator, the following drawings are combined to elaborate in detail.

[0046] Figure 2 Another diagram of the vacuum microcavity interferometer chip according to the embodiment of the present disclosure is shown. In the diagram, the fiber collimator 40 is arranged to extend into the vacuum microcavity interferometer chip 100 from the lower surface of the third base structure through the optical through hole 31, and the working end face of the fiber collimator 40 is arranged to face and be parallel to the first transmission face 22, and the central axis of the fiber collimator 40 coincides with the central axis of the first transmission face 22, so as to improve the pressure measurement accuracy. In particular, the second flat-bottomed groove 33 is arranged on the side of the optical through hole 31 close to the lower surface of the third base structure; the second flat-bottomed groove 33 is used to provide positioning and shear-resistant support for the solder 42 for fixing the fiber collimator 40 and the glass protection tube 41 for the fiber collimator.

[0047] Figure 3 The top view and the bottom view of the vacuum microcavity interferometer chip according to the embodiment of the present disclosure are shown. In the diagram, the upper diagram is the top view of the vacuum microcavity interferometer chip, and it can be seen that the square frame is the upper surface of the second base structure, and the circular frame is the upper surface of the first base structure, so that the symmetry of the first base structure 10 and the second base structure 20 relative to the central axis thereof can be better seen. While the lower diagram is the bottom view of the vacuum microcavity interferometer chip, and it can be seen that the large square frame is the lower surface of the second base structure, and the small square frame is the lower surface of the third base structure, so that the symmetry of the second base structure 20 and the third base structure 30 relative to the central axis thereof can be better seen. In addition, the diameter of the circular frame of the first base structure 10 and the side length of the square frame of the third base structure 30 are the same, which is shown by the dashed line, so as to facilitate the processing of the coinciding of the central axes of the first base structure 10, the second base structure 20 and the third base structure 30, and to ensure that the side walls of the first base structure 10 and the third base structure 30 have a larger projected coinciding area (the projected coinciding area on the second base structure 20) when the wall thicknesses thereof are the same, so that the second base structure 20 is not easily damaged when the first base structure 10 and the third base structure 30 are pressed towards the second base structure 20.

[0048] Further, the following drawings are combined to elaborate in detail for the assembly of the vacuum microcavity interferometer chip on the high-sensitivity optical pressure sensor.

[0049] Figure 4 The diagram of the high-sensitivity optical pressure sensor according to the embodiment of the present disclosure is shown. In the diagram, and referring to Figure 5Fig. 10 shows a high-sensitivity optical pressure sensor 1000 comprising the above-mentioned vacuum microcavity interferometer chip 100, a fiber collimator 40 arranged to extend from the third substrate structure lower surface into the above-mentioned vacuum microcavity interferometer chip 100 through the above-mentioned optical via 31, and the working end face of the above-mentioned fiber collimator 40 is arranged to face and be parallel to the above-mentioned first transmission face 22, and the central axis of the above-mentioned fiber collimator 40 coincides with the central axis of the above-mentioned first transmission face 22. It should also be noted that by arranging the second substrate structure lower surface to laterally overhang the portion of the third substrate structure lower surface, i.e. the second substrate structure lower surface is arranged to laterally overhang the portion of the third substrate structure lower surface, the second substrate structure is arranged to have an outer dimension larger than the exposed surface formed by the first substrate structure and the third substrate structure, which enables the sensor housing to be bonded or soldered to the second substrate structure, and in turn the first substrate structure and the third substrate structure and the fiber collimator are not connected to the sensor housing by solder or adhesive, which improves the spectral quality and stability of the vacuum microcavity interferometer chip and the high-sensitivity optical pressure sensor comprising the same.

[0050] Furthermore, the present disclosure is not intended to change the principle of sensing pressure by fiber F-P cavity.

[0051] The above has described various embodiments of the present disclosure, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles, practical applications, or technical improvements in the art, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

[0052] The above is only an optional embodiment of the present disclosure, and is not intended to limit the present disclosure. The present disclosure can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A vacuum microcavity interferometer chip, characterized by Comprising: a first substrate structure, a second substrate structure and a third substrate structure; the first substrate structure is configured with a first substrate structure upper surface and a first substrate structure lower surface, the first substrate structure upper surface is configured as a membrane-island structure with an upper surface surrounded by side surfaces, the first substrate structure lower surface is provided with a first reflecting surface; the second substrate structure is configured with a second substrate structure upper surface and a second substrate structure lower surface, the second substrate structure is disposed between the first substrate structure side towards the first substrate structure lower surface and the third substrate structure side towards the third substrate structure upper surface, the second substrate structure upper surface is configured with a second reflecting surface opposite and parallel to the first reflecting surface; the third substrate structure is configured with a third substrate structure upper surface and a third substrate structure lower surface, the third substrate structure is configured with an optical through hole through the third substrate structure upper surface and the third substrate structure lower surface; the first substrate structure, the second substrate structure and the third substrate structure are respectively configured as structures symmetrical with respect to their central axes; the first substrate structure lower surface is provided to connect with the second substrate structure upper surface, the second substrate structure lower surface is provided to connect with the third substrate structure upper surface.

2. The vacuum microcavity interferometer chip according to claim 1, wherein: the first substrate structure lower surface is configured as a concave cavity, the concave cavity of the first substrate structure and the upper surface of the second substrate structure are provided as an F-P interference cavity; in the F-P interference cavity, the first substrate structure lower surface is provided with the first reflecting surface; the surface of the island of the membrane-island structure is provided with a top transmitting surface.

3. The vacuum microcavity interferometer chip according to claim 2, wherein: the projection area of the second substrate structure in the lateral direction is greater than the projection area of the first substrate structure in the lateral direction or the projection area of the third substrate structure in the lateral direction.

4. The vacuum microcavity interferometer chip according to claim 3, wherein: the part of the second substrate structure lower surface laterally beyond the third substrate structure is provided as the second substrate structure lower exposed surface.

5. The vacuum microcavity interferometer chip according to claim 1, wherein: the first substrate structure is configured as a quasi-cylindrical structure, the first substrate structure upper surface is configured as a membrane-island structure with a circular frame; the second substrate structure and the third substrate structure are configured as square-frame quasi-cuboid structures; the first substrate structure, the second substrate structure and the third substrate structure are provided with coinciding central axes.

6. The vacuum microcavity interferometer chip according to claim 5, wherein: the diameter of the circular frame of the first substrate structure is the same as the side length of the square frame of the third substrate structure.

7. The vacuum microcavity interferometer chip according to claim 1, wherein: the optical through hole is provided with a first flat-bottomed groove on the side close to the third substrate structure upper surface.

8. The vacuum microcavity interferometer chip of claim 1, wherein, a second flat-bottomed groove is provided on a side periphery of the optical via near the third substrate structure lower surface side.

9. The vacuum microcavity interferometer chip of claim 2, wherein, the second substrate structure lower surface is configured with a first transmission surface parallel to the second reflection surface; and the first reflection surface, the second reflection surface, the first transmission surface, the top transmission surface, and a central axis of the optical via coincide.

10. The vacuum microcavity interferometer chip of claim 1, wherein, a getter film is deposited on a periphery of the second reflection surface.

11. The vacuum microcavity interferometer chip of claim 1, wherein, the first substrate structure is configured with an SOI silicon wafer, which is a three-layer structure of a top layer of silicon, a buried oxygen layer, and a bottom layer of silicon; the second substrate structure is configured with a glass substrate; the third substrate structure is configured with a double-polished silicon wafer.

12. A high-sensitivity optical pressure sensor, characterized by, including: the vacuum microcavity interferometer chip of any one of claims 1-11; an optical fiber collimator configured to extend into the vacuum microcavity interferometer chip from the third substrate structure lower surface through the optical via, and an operating end surface of the optical fiber collimator is configured to face and be parallel to the first transmission surface, and a central axis of the optical fiber collimator coincides with a central axis of the first transmission surface.

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