Vacuum microcavity interferometer chip, manufacturing method and wide-range optical pressure sensor

Abstract

The present invention relates to a vacuum microcavity interferometer chip, a manufacturing method and a wide-range optical pressure sensor. The chip comprises a first substrate and a second substrate, the second substrate is bonded to the first substrate as a whole, a pressure-sensitive film is made on the first substrate, a first reflection surface is deposited on the pressure-sensitive film, a second reflection surface arranged corresponding to the first reflection surface is deposited on the second substrate, when the two substrates are bonded, the first reflection surface and the second reflection surface form an F-P optical interference cavity, at least one getter cavity is arranged on the first substrate and / or the second substrate, a getter film is arranged on the surface of the getter cavity, the getter cavity is separated from the F-P optical interference cavity, and is connected through an airway, so that the size of the airway can be made very small, so as to avoid a small amount of particles generated after the getter is activated from contaminating the optical film and causing device failure; the sensor is a sealed structure as a whole, and there is no structure connected to the outside of the chip, so as to ensure the airtightness of the chip as a whole and reduce the vacuum degree requirement of the subsequent shell packaging.

Description

Technical Field

[0001] The present invention relates to sensors in the field of optoelectronic technology, and specifically to a wide-range vacuum microcavity interferometer chip based on the principle of a vacuum microcavity multi-beam interferometer, a manufacturing method and a sensor thereof, which are mainly used for measuring pressure signals of fluid media such as gas and liquid, and can also be used for measuring and controlling flow, flow velocity, density, liquid level, altitude, contact force between objects, etc. Background Art

[0002] Pressure sensor refers to a device or apparatus that can sense the pressure signal of fluid media such as gas and liquid, and can convert the pressure signal into a usable output electrical signal or optical signal according to certain rules. Pressure sensor is the most commonly used sensor in industrial practice. It is widely used in various industrial automatic control environments such as water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military industry, petrochemical, oil wells, electricity, ships, machine tools, pipelines, etc., and is also increasingly widely used in consumer electronics fields such as medical equipment, robots and automotive electronics, smart phones, smart home appliances and wearable electronic products.

[0003] The price of pressure sensor products mainly depends on the applicable use conditions and the measurement accuracy that can be maintained for a long time. The price of industrial-grade pressure sensors with an accuracy of 0.01% in the working temperature range of -55℃ to 85℃ and pressure sensors with a temperature resistance of more than 200℃ and an accuracy of 0.1% in the whole temperature range are several thousand yuan or even tens of thousands of yuan. Pressure sensors with wide temperature range, high accuracy and high reliability have huge application demands in many fields such as nuclear power, aerospace, rail transportation, semiconductor equipment and process industry. Pressure sensors can be classified according to the detection method, such as electrical detection and optical detection pressure sensors. At present, among the electrical detection pressure sensors, resonant pressure sensors have a series of advantages such as high temperature stability, high long-term stability and high comprehensive accuracy and are widely recognized by the market. However, their use in high temperature, or radiation, electromagnetic interference and other occasions will be restricted, while optical fiber pressure sensors can meet the use requirements of the above occasions. Optical fiber sensing technology is a new technology that has developed rapidly in the late 1970s. It is the application of fiber optics in non-communication fields. Fiber optic sensing technology can measure more than one hundred physical quantities. Its advantages are: wide range of applications, high sensitivity, anti-electromagnetic interference, good insulation, corrosion resistance, flexibility, small size, low cost, and good compatibility with fiber optic transmission lines, etc.

[0004] The fiber FP (Fabry-Perot) pressure sensor is a type of fiber optic pressure sensor. It usually consists of a fiber end face and a diaphragm end face to form a Fabry-Perot micro-resonant cavity. When pressure acts on the pressure-sensitive membrane, it deforms, causing the length of the Fabry-Perot cavity to change, thereby achieving sensing measurement. The fiber optic Fabry-Perot pressure sensor has a simple structure and is relatively easy to implement. It is currently the most commonly used interference fiber optic pressure sensor. The pressure-sensitive membrane of some sensors is made using the micro-electromechanical (MEMS) bulk silicon process and the surface sacrificial layer process; the pressure-sensitive membrane of some sensors is made using the fiber optic corrosion fusion process. In recent years, some design schemes have emerged. For example, in 2001, Jie Zhou, Samhita Dasgupta, et al. Optically interrogated MEMS pressure sensors for propulsion applications, Optical Engineering, 2001, 40: 598-604. of Cincinnati University used bulk silicon technology to make a fiber optic Fabry-Perot pressure sensor: a single-crystal silicon film was used as a pressure-sensitive film, and a shallow cylindrical cavity was etched on the glass with HF buffer solution. The silicon film and the glass were tightly bonded together using an electrostatic bonding process to form a Fabry-Perot cavity. Finally, the optical fiber and the sensor chip were aligned and bonded with epoxy resin. Since epoxy resin creeps under the influence of the external environment, the coupling angle between the optical fiber and the sensor chip will change, causing the zero-point output of the sensor to drift.

[0005] MEMS fiber optic pressure sensors combine the advantages of miniaturization, high reliability and high consistency of MEMS technology with the advantages of fiber optic signal readout technology, greatly expanding the scope of use of high-precision pressure sensors. High-precision MEMS fiber optic sensors usually use wavelength demodulation, especially FP optical interference cavity (Fabry-Perot) interference. Its working principle is to integrate the pressure-sensitive film with the optical FP optical interference cavity. The external pressure causes the pressure-sensitive film to produce a translational displacement. The cavity length of the FP optical interference cavity changes synchronously, and its interference wavelength also changes. The change in wavelength is read out through the optical fiber, thereby measuring the external pressure. For details, please refer to the Chinese patent application CN201410728291.6 in the prior art, which discloses the use of FP optical interference cavity to measure pressure. The sensor has a membrane island structure arranged in the FP optical interference cavity.

[0006] Since the dynamic detection resolution of the cavity length of the multi-beam FP interferometer can reach 1pm to 10pm, while the dynamic detection resolution of the cavity length of the dual-beam FP interferometer can only reach the order of 100pm to 1nm, the sensitivity of the pressure sensor can be greatly improved by constructing a multi-beam FP interferometer inside the pressure sensitive chip. However, the construction of the multi-beam FP interferometer requires the deposition of optical films to improve the optical reflectivity of the two reflection surfaces of the FP interferometer, and there are very high requirements for the parallelism and cleanliness of the two reflection surfaces in order to maintain the laser signal incident into the cavity to form hundreds of reflections between the two reflection surfaces to meet the basic conditions of multi-wavelength interference. Limited by the temperature resistance range of 500℃~600℃ of the optical film, only the silicon-glass bonding process with a temperature range of 300℃~400℃ can ensure that the optical film on the reflective surface of the multi-beam FP interferometer inside the MEMS chip remains intact. However, the gas released by the silicon-glass bonding will cause the vacuum degree of the interference cavity inside the multi-beam FP interferometer to decrease and form an unstable refractive index, which affects the low-pressure measurement range and zero-point stability of the MEMS pressure-sensitive chip, and will also increase the temperature coefficient and reduce the measurement repeatability. In order to perform high-precision pressure measurements, this type of sensor usually needs to evacuate the inside of the FP optical interference cavity, and its vacuum degree needs to be kept stable. Usually, some residual gas will remain 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 FP optical interference cavity to achieve a high vacuum inside the pressure sensor. Chinese patent application CN20121017590.0 discloses a MEMS chip packaging structure. Usually, the getter is deposited inside the FP optical interference cavity by PVD (physical vapor deposition). To ensure that the residual gas is absorbed cleanly, the getter usually occupies a large area. Therefore, when the sensor range is increased by reducing the area of ​​the pressure sensitive membrane, it will be limited by the getter area; on the other hand, the getter is a porous structure with poor density. The getter will produce particles when heated or vibrated by the outside world, polluting the FP optical interference cavity, potentially causing spectral degradation, and having a greater impact on the measurement of optical sensors, especially, and causing device failure in severe cases. Chinese patent application CN201410264998.6 relates to a hybrid wafer-level vacuum packaging method, in which a getter cavity is provided on the side of the chip packaging cavity and is connected through a vent hole. After the getter is fixed in the getter cavity, a cover plate is fixed. This structure and method also have the potential possibility of the getter contaminating the FP optical interference cavity. In this method, the getter cavity and the getter are superimposed after the chip is formed, and the manufacturing process is complicated; and there is a certain possibility that the getter particles enter the working cavity through the vent hole channel. The getter particles have a certain insulation property, and have little effect on electrical detection sensors.

[0007] When the getter is manufactured inside or above or below the pressure sensitive structure, the presence of the getter will limit the reduction of the area of ​​the pressure sensitive structure. The sensor structure of Chinese patent application CN201410728291.6 requires a relatively small pressure sensitive film when measuring large pressures, and the relatively small pressure sensitive film reduces the volume of the FP optical interference cavity, which brings challenges to the arrangement of the getter film.

[0008] In addition, after the MEMS pressure sensitive chip and the optical fiber coupling package form a MEMS optical pressure module, it is usually necessary to perform secondary packaging and fix it on the pressure sensor housing to achieve isolation and protection from sealing pressure taking, module measurement to lead-out cable, so as to become a MEMS optical pressure sensor that can be installed and used independently. During the secondary packaging process, whether the external mechanical force on the housing is transmitted to the MEMS pressure sensitive chip or to the welding and packaging part between the MEMS pressure sensitive chip and the optical fiber, the multi-beam FP interferometer will be subjected to uneven stress, causing the interference spectrum to deteriorate, resulting in abnormal changes in the measured value, and also causing the sensor zero point output to drift. Summary of the invention

[0009] In view of the shortcomings of the optical fiber pressure sensor in the prior art, the present application provides a vacuum microcavity interferometer chip, including a first substrate and a second substrate, wherein the first substrate is preferably a silicon substrate or a silicon nitride wafer or other substrates with similar functions, and the second substrate is a glass substrate or a sapphire or other substrates with similar functions, and can be fixed by silicon-glass bonding or bonding through a corresponding dielectric layer such as BCB glue, a gold layer or a glass slurry; the second substrate is bonded to the first substrate as a whole, a pressure-sensitive film is made on the first substrate, a first reflection surface is deposited on the pressure-sensitive film, and a pressure-sensitive film corresponding to the first reflection surface is deposited on the second substrate. The second reflection surface, when the two substrates are bonded, the first reflection surface and the second reflection surface form a FP optical interference cavity; at least one getter cavity is disposed on the first substrate and / or the second substrate, a getter film is disposed on the surface of the getter cavity, the getter cavity and the FP optical interference cavity are connected through an air channel, and the first reflection surface and the second reflection surface are disposed in the FP optical interference cavity; after the second substrate is bonded to the first substrate as one body, the getter cavity forms a closed structure, and is only connected to the FP optical interference cavity through the air channel; a fiber collimator is installed on the side of the second substrate away from the first substrate. Through the above structure, the getter cavity and the FP optical interference cavity are connected through the air channel, and the getter cavity can be disposed separately, which ensures that the getter cavity has enough surface area to absorb the residual gas in the FP optical interference cavity, and also ensures that the area of ​​the pressure sensitive film is small enough when measuring large pressure, so as to meet the requirements of high-sensitivity pressure measurement within a wide range.

[0010] In a further preferred embodiment, in order to reduce the bending of the center of the pressure sensitive film under the action of external pressure, the pressure sensitive film is a film-island structure with a thick center and a thin periphery.

[0011] In a further preferred embodiment, the getter cavity is arranged on the first substrate. Since the etching process of the silicon substrate is relatively mature, the getter cavity is arranged on the first substrate to reduce the manufacturing cost. Furthermore, the number of the getter cavities is more than two, and the multiple getter cavities are arranged symmetrically about the FP optical interference cavity, so that the vacuum degree of the FP optical interference cavity can be reduced to the maximum extent, so that the vacuum degree of the FP optical interference cavity is maintained at 10 -5 Pa high vacuum reference environment.

[0012] Further preferably, the number of the getter cavities is two or four, and the two or four getter cavities are centrally symmetrically arranged about the FP optical interference cavity, so that the temperature coefficients of the left and right ends and / or the upper and lower ends of the sensor can be consistent, avoiding the different deformation amounts on the two sides during thermal expansion and contraction caused by the asymmetry of the two sides, thereby reducing the difficulty of temperature compensation of the sensor.

[0013] In a further preferred embodiment, an optical anti-reflection film is deposited on the side of the second substrate facing away from the first substrate, and the second reflecting surface and the optical anti-reflection film are deposited on two different surfaces of the second substrate and their centers coincide. There is also a third substrate, which is a silicon substrate, and is formed as a whole with the second substrate through a bonding process. A mounting hole is provided on the third substrate and a fiber collimator is installed thereon, and the first reflecting surface, the second reflecting surface, the optical anti-reflection film, the mounting hole and the fiber collimator have the same axis.

[0014] In a further preferred embodiment, the diameter of the air channel is 10-100 microns, so that even in extreme cases, the getter film may generate particles due to external heating or vibration, and the diameter of the air channel can limit the flow of particles into the FP optical interference cavity.

[0015] In a preferred embodiment, the size of the second substrate is larger than that of the first substrate and the third substrate. Therefore, when the vacuum microcavity interferometer chip is used to make a sensor, the second substrate is larger than the first substrate and the third substrate to form an exposed surface for bonding or welding to the sensor housing, so that the first substrate, the third substrate and the optical fiber collimator are not in contact with the sensor housing; stress isolation is achieved between the membrane island structure of the vacuum microcavity interferometer chip, the optical fiber collimator on the third substrate and the sensor housing. When the sensor housing is subjected to force or vibration, it will be directly transmitted to the second substrate. Since the first substrate and the third substrate are arranged on both sides of the second substrate and have a roughly symmetrical structure, the first substrate and the third substrate will vibrate as a whole, and will not apply stress to the membrane island structure and the optical fiber collimator on the third substrate, thereby reducing the zero-point output change of the vacuum microcavity interferometer chip before and after mechanical fastening and installation on site or when it is impacted by external force.

[0016] The present invention also relates to a method for manufacturing a vacuum microcavity interferometer chip, which specifically includes: 1) etching a getter cavity, an airway and a pressure-sensitive film on a first substrate; one side of the pressure-sensitive film is used to sense pressure, and the other side has a roughly concave cavity structure, so that the thickness of the pressure-sensitive film is less than the thickness of the first substrate, and can be deformed under pressure. The thickness of the pressure-sensitive film determines the amount of deformation under the same pressure, and a suitable thickness can be selected according to the measured pressure range; 2) depositing a first reflective surface on the pressure-sensitive film; 3) a second substrate film layer deposition step: depositing a getter film, a second reflective surface on the second substrate corresponding to the getter cavity, the first reflective surface on the pressure-sensitive film and the mounting hole; and an optical anti-reflection film; by completing the getter film, the second reflective surface and the optical anti-reflection film in the second substrate film layer deposition step, compared with the traditional airtight packaging method in which the getter cavity and the getter are superimposed in the back-end process after the chip is formed, the manufacturing process is simpler and the laminated substrate is less; at the same time, the getter film is deposited on the second substrate, which reduces the potential deformation of the pressure-sensitive film caused by the getter film stress compared to setting it on the first substrate; 4) the first substrate, the second substrate and the third substrate are bonded together at a temperature greater than 300°C; the bonding temperature exceeds the activation temperature of the getter film, so the getter film is activated during the bonding process, so there is no need to activate the getter after the device is manufactured. When external pressure exists, the external pressure will cause the pressure-sensitive film to produce a translational displacement, the cavity length of the FP optical interference cavity changes synchronously, and its interference wavelength also changes. The spectral signal is coupled and transmitted to the full spectrum analyzer at the back end through the optical fiber to read the interference wavelength or the change of the continuous wavelength across multiple free spectrum domains, thereby measuring the external pressure. Due to the high vacuum state in the cavity, the pressure sensor of the present invention can measure absolute pressures smaller than atmospheric pressure. When it is necessary to measure a pressure of 10 MPa or greater, the area of ​​the pressure sensitive film can be reduced to meet the range requirements without considering the restriction of the area occupied by the getter.

[0017] In a further preferred embodiment, the getter film has poor stability and will react with a variety of solutions during the PVD deposition process. In the second base film layer deposition step, the getter film is selected to be deposited last; that is, the getter film is deposited after the second reflective surface and the optical anti-reflection film are deposited.

[0018] The present application also relates to a pressure sensor, comprising a sensor housing and a chip mounting seat arranged in the sensor housing, wherein the vacuum microcavity interferometer chip is fixed in contact with the sensitive chip mounting seat only through the second substrate. This structure can achieve stress isolation between the membrane island structure of the vacuum microcavity interferometer chip, the optical fiber collimator on the third substrate and the sensor housing. When the sensor housing is subjected to force or vibration, it will be directly transmitted to the second substrate. Since the first substrate and the third substrate are arranged on both sides of the second substrate and have a roughly symmetrical structure, the first substrate and the third substrate will vibrate as a whole, and will not apply stress to the membrane island structure and the optical fiber collimator on the third substrate, thereby ensuring that the zero-point output of the vacuum microcavity interferometer chip does not change before and after mechanical fastening and installation on site or when subjected to external force impact.

[0019] The MEMS pressure sensor of the present invention integrates the MEMS structure with the high-precision optical FP optical interference cavity for manufacturing, so it naturally has the characteristics of high precision; adding a getter in the sensor structure can absorb the residual gas in the FP optical interference cavity, thereby improving the zero point stability of the sensor and achieving higher detection accuracy; the getter cavity and the optical FP optical interference cavity in the MEMS pressure sensor chip can be set in the front-end process, compared with the traditional airtight packaging method in which the getter cavity and the getter are superimposed in the back-end process after the chip is formed, the manufacturing process is simpler and the laminated substrate is less; the getter cavity is separated from the FP optical interference cavity and connected through an airway, so the size of the airway can be made very small , to avoid the small amount of particles generated after the activation of the getter from contaminating the optical film and causing device failure; according to the needs of use, the FP optical interference cavity area (i.e., the pressure-sensitive film area) and the getter area can be adjusted independently without affecting each other; the MEMS sensor is a sealed structure as a whole, without any physical channels or structures connected to the outside of the chip, which ensures the airtightness of the chip as a whole and reduces the vacuum requirements for subsequent shell packaging; the chip adopts a three-layer bonding structure, which integrates and miniaturizes multiple structures and materials such as pressure-sensitive film, optical FP optical interference cavity and getter; the bonding temperature is controlled to activate the getter film during the bonding process, which simplifies the manufacturing process of the sensor and eliminates the need to consume energy to activate the getter film separately. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall structure of the MEMS pressure sensor of the present invention;

[0021] Figure 2 A bottom view of the first substrate of the present invention;

[0022] Figure 3 is a top view of the second substrate of the present invention;

[0023] Figure 4 is a schematic diagram of another embodiment of the present invention;

[0024] Figure 5 It is a structural schematic diagram of the wide-range optical pressure sensor of the present invention;

[0025] Figure 6 For the present invention Figure 5 A partial enlarged schematic diagram of the structure;

[0026] Figure 7 The present invention is a flowchart of a method for manufacturing a MEMS sensor.

[0027] Description of reference numerals:

[0028] 1-first substrate; 11-pressure sensitive film; 12-first reflection surface; 13-second reflection surface; 14-getter cavity; 15-getter film; 16-air channel; 2-second substrate; 21-optical antireflection film; 3-third substrate; 4-fiber collimator; 5-sensor; 51-sensor housing; 52-chip mounting seat. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0031] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0032] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In view of the shortcomings of pressure sensors in the prior art, the present application provides a vacuum microcavity interferometer chip, including a first substrate 1 and a second substrate 2, wherein the first substrate is preferably a substrate with similar functions such as a silicon substrate or a silicon nitride wafer, and the second substrate is a substrate with similar functions such as a glass substrate or a sapphire substrate, and can be bonded and fixed using silicon-glass bonding or a corresponding dielectric layer such as BCB glue, a gold layer or a glass slurry; the second substrate 2 is bonded to the first substrate 1 as a whole, a pressure-sensitive film 11 is made on the first substrate 1, a first reflection surface 12 is deposited on the pressure-sensitive film 11, and a second reflection surface 13 corresponding to the first reflection surface 12 is deposited on the second substrate 2, and when the two substrates are bonded, the first reflection surface and the second reflection surface form an FP optical interference cavity; at least one getter cavity 14 is arranged on the first substrate 1 and / or the second substrate 2, Figure 1 It is shown that the getter cavity and the FP optical interference cavity are arranged on the first substrate. In other embodiments, the getter cavity 14 and the FP optical interference cavity can be arranged on the second substrate, or the getter cavity 14 and a part of the FP optical interference cavity are arranged on the first substrate, and the other part is arranged on the second substrate. A getter film 15 is arranged on the surface of the getter cavity 14, and the getter cavity 14 and the FP optical interference cavity are connected through an air channel 16. The first reflection surface 12 and the second reflection surface 13 are arranged in the FP optical interference cavity; after the second substrate 2 is bonded to the first substrate 1 as a whole, the getter cavity 14 forms a closed structure, and has no other openings except the air channel 16, and is only connected to the FP optical interference cavity through the air channel 16, as shown in FIG. Figure 1 Through the above structure, the getter cavity 14 is connected to the FP optical interference cavity through the air channel 16, and the getter cavity 14 can be set separately, which ensures that the getter cavity 14 has enough surface area to absorb the residual gas in the FP optical interference cavity, and also ensures that the area of ​​the pressure sensitive film 11 is small enough during large pressure measurement to meet the corresponding measurement sensitivity requirements.

[0034] In a further preferred embodiment, in order to reduce the bending of the center of the pressure sensitive film 11 under the action of external pressure, the pressure sensitive film 11 is a film-island structure with a thick center and a thin periphery.

[0035] In a further preferred embodiment, the getter cavity 14 is arranged on the first substrate 1. Since the etching process of the silicon substrate is relatively mature, the getter cavity 14 is arranged on the first substrate 1, which can reduce the manufacturing cost; further, the number of the getter cavities 14 is more than two, and the multiple getter cavities 14 are arranged symmetrically about the FP optical interference cavity, so that the vacuum degree of the FP optical interference cavity can be reduced to the maximum extent, so that the vacuum degree of the FP optical interference cavity is maintained at 10- 5 Pa high vacuum reference environment.

[0036] Further preferably, the number of the getter cavities 14 is two or four, and the two or four getter cavities 14 are centrally symmetrically arranged with respect to the FP optical interference cavity. Figure 2 It is shown in the figure that two getter cavities 14 are set in the MEMS sensor and located at the left and right ends thereof, so that the temperature coefficients of the left and right ends and / or the upper and lower ends of the sensor can be consistent, avoiding the different deformation amounts of the two sides due to thermal expansion and contraction caused by asymmetry of the two sides, thereby reducing the difficulty of temperature compensation of the sensor.

[0037] In a further preferred embodiment, an optical anti-reflection film 21 is deposited on the side of the second substrate 2 facing away from the first substrate 1, and the second reflecting surface 13 and the optical anti-reflection film 21 are deposited on two different surfaces of the second substrate 2 and their centers coincide. There is also a third substrate 3, which is a silicon substrate. The third substrate 3 is formed as a whole with the second substrate 2 through a bonding process, and a mounting hole is provided on the third substrate 3 and a fiber collimator 4 is installed thereon. The first reflecting surface 12, the second reflecting surface 13, the optical anti-reflection film 21, the mounting hole and the fiber collimator 4 have the same axis.

[0038] In a further preferred embodiment, the diameter of the air channel 16 is 10-100 microns, so that even in extreme cases, the getter film 15 may generate particles due to external heating or vibration, and the diameter of the air channel 16 can limit the flow of particles into the FP optical interference cavity.

[0039] In a preferred embodiment, the size of the second substrate 2 is larger than that of the first substrate 1 and the third substrate 3. Figure 4 As shown in ; the dimension may be a parameter such as length or diameter, depending on the shape of the second substrate, and it is sufficient to ensure that the second substrate is partially exposed from the first substrate or the third substrate; therefore, when the vacuum microcavity interferometer chip is used to make a sensor, the second substrate is larger than the first substrate and the third substrate to form an exposed surface to be bonded or welded to the sensor housing, so that the first substrate and the third substrate and the optical fiber collimator are not in contact with the sensor housing; stress isolation is achieved between the membrane island structure of the vacuum microcavity interferometer chip, the optical fiber collimator on the third substrate and the sensor housing, and when the sensor housing is subjected to force or vibration, it will be directly transmitted to the second substrate. Since the first substrate and the third substrate are arranged on both sides of the second substrate and have a roughly symmetrical structure, the first substrate and the third substrate will vibrate as a whole, and stress will not be applied to the membrane island structure and the optical fiber collimator on the third substrate, thereby ensuring that the zero-point output of the vacuum microcavity interferometer chip does not change before and after mechanical fastening and installation on site or when subjected to external force impact.

[0040] The present invention also relates to a method for manufacturing a sensor for measuring pressure, such as Figure 7 As shown in, it specifically includes: 1) etching a getter cavity 14, an air channel 16 and a pressure sensitive film 11 on a first substrate 1; one side of the pressure sensitive film 11 is used to sense pressure, and the other side has a roughly concave cavity structure, so that the thickness of the pressure sensitive film 11 is less than the thickness of the first substrate, and can produce a translational displacement under the action of pressure. The thickness of the pressure sensitive film 11 determines the displacement under the same pressure, and a suitable thickness can be selected according to the measured pressure range; 2) depositing a first reflective surface 12 on the pressure sensitive film 11; 3) a second substrate film layer deposition step: a getter film 15, a second reflective surface 13 and an optical anti-reflection film 21 are deposited on the second substrate 2 at positions corresponding to the getter cavity 14, the pressure sensitive film 11 and the mounting hole, as shown Figure 3 As shown in ; by completing the getter film, the second reflection surface 13 and the optical anti-reflection film 21 in the second substrate film layer deposition step, compared with the traditional airtight packaging method in which the getter cavity 14 body and the getter are superimposed after the chip is formed, that is, in the back-end process, the manufacturing process is simpler and the laminated substrate is less; at the same time, the getter film 15 is deposited on the second substrate 2, compared with being set on the first substrate 1, the potential possibility of deformation of the pressure sensitive film 11 is reduced; 4) the first substrate 1, the second substrate 2 and the third substrate 3 are formed into one by bonding at a temperature greater than 300°C; the bonding temperature exceeds the activation temperature of the getter film 15, so the activation of the getter film 15 is completed during the bonding process, so there is no need to activate the getter after the device is manufactured. When external pressure exists, the external pressure will cause the pressure sensitive film 11 to produce a translational displacement, the cavity length of the FP optical interference cavity changes synchronously, and its interference wavelength also changes. The spectral signal is coupled and transmitted to the full spectrum analyzer at the back end through the optical fiber to read the interference wavelength or the change of the continuous wavelength across multiple free spectrum domains, thereby measuring the external pressure. Due to the high vacuum state in the cavity, the pressure sensor of the present invention can measure absolute pressures smaller than atmospheric pressure. When it is necessary to measure a pressure of 10 MPa or greater, the area of ​​the pressure sensitive film can be reduced to meet the range requirements without considering the restriction of the area occupied by the getter.

[0041] In a further preferred embodiment, the getter film has poor stability and will react with a variety of solutions during the PVD deposition process. In the second base film layer deposition step, the getter film is selected to be deposited last; that is, the getter film is deposited after the second reflective surface 13 and the optical anti-reflection film 21 are deposited.

[0042] The present application also relates to a wide-range optical pressure sensor, comprising a sensor housing 51 and a chip mounting seat 52 arranged in the sensor housing 51, Figure 5and 6 As shown in ; the vacuum microcavity interferometer chip is fixed in contact with the sensitive chip mounting seat only through the second substrate. This structure can achieve stress isolation between the membrane island structure of the vacuum microcavity interferometer chip, the fiber collimator on the third substrate and the sensor housing. When the sensor housing is subjected to force or vibration, it will be directly transmitted to the second substrate. Since the first substrate and the third substrate are arranged on both sides of the second substrate with a roughly symmetrical structure, the first substrate and the third substrate will vibrate as a whole, and will not apply stress to the membrane island structure and the fiber collimator on the third substrate, ensuring that the zero-point output of the vacuum microcavity interferometer chip does not change before and after mechanical fastening and installation on site or when impacted by external force.

Claims

1. A vacuum microcavity interferometer chip, comprising a first substrate and a second substrate; characterized in that: A pressure sensitive film is made on the first substrate, a first reflective surface is deposited on the pressure sensitive film, a second reflective surface corresponding to the first reflective surface is deposited on the second substrate, and when the two substrates are bonded, the first reflective surface and the second reflective surface form an FP optical interference cavity; At least one getter cavity is arranged on the first substrate and / or the second substrate, a getter film is arranged on the surface of the getter cavity, the getter cavity and the FP optical interference cavity are connected through an air channel, and the first reflection surface and the second reflection surface are arranged in the FP optical interference cavity; after the second substrate is bonded to the first substrate as one, the getter cavity is formed into a closed structure, and is only connected to the FP optical interference cavity through the air channel; a fiber collimator is installed on the side of the second substrate away from the first substrate; further, a third substrate is also provided, a mounting hole is arranged on the third substrate and the fiber collimator is installed, and the first reflection surface, the second reflection surface, the optical anti-reflection film, the mounting hole and the fiber collimator have the same axis; The second substrate has a larger outer dimension than the first substrate and the third substrate. The second substrate has an exposed surface that is fixed to the sensor housing by utilizing the fact that the outer dimension of the second substrate is larger than that of the first substrate and the third substrate.

2. The vacuum microcavity interferometer chip according to claim 1, characterized in that: The pressure sensitive film is a film-island structure with a thick center and a thin periphery.

3. The vacuum microcavity interferometer chip according to any one of claims 1 to 2, characterized in that: The getter cavity is disposed on the first substrate.

4. The vacuum microcavity interferometer chip according to claim 3, characterized in that: The number of the getter cavities is two or four, and the two or four getter cavities are centrally symmetrically arranged with respect to the FP optical interference cavity.

5. The vacuum microcavity interferometer chip according to claim 3, characterized in that: An optical anti-reflection film is deposited on the side of the second substrate facing away from the first substrate, and the second reflecting surface and the optical anti-reflection film are deposited on two different surfaces of the second substrate with their centers overlapping.

6. The vacuum microcavity interferometer chip according to claim 3, characterized in that: The diameter of the airway is 10-100 microns.

7. The vacuum microcavity interferometer chip according to claim 3, characterized in that: The getter film is deposited on the second substrate.

8. A method for manufacturing a vacuum microcavity interferometer chip according to any one of claims 1 to 7, comprising: 1) etching a getter cavity, an air channel, and a pressure sensitive film on a first substrate; 2) depositing a first reflective surface on the pressure sensitive film; 3) Second substrate film layer deposition step: a getter film, a second reflective surface and an optical anti-reflection film are deposited on the second substrate at positions corresponding to the getter cavity, the first reflective surface and the mounting hole; 4) The first substrate, the second substrate and the third substrate are bonded together at a temperature greater than 300°C.

9. The method for manufacturing a vacuum microcavity interferometer chip according to claim 8, characterized in that: In the second base film layer deposition step, the getter film is selected to be deposited last.

10. A wide-range optical pressure sensor, comprising a sensor housing and a chip mounting seat arranged in the sensor housing, wherein the vacuum microcavity interferometer chip according to any one of claims 1 to 7 is fixed in contact with the chip mounting seat only through the second substrate.

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