Sensitive structure of pressure sensor

Abstract

The invention relates to the technical field of force measurement, and provides a pressure sensor sensitive structure which comprises a pressure sensing layer, a vibrating beam layer, a stress isolation layer and a substrate layer. The pressure sensing layer comprises a pressure sensing film, the pressure sensing film is provided with a first concave cavity, a second concave cavity and a boss, the first concave cavity is formed in the first side of the pressure sensing film, the second concave cavity is formed in the second side of the pressure sensing film, the first side of the pressure sensing film is opposite to the second side of the pressure sensing film, and the boss is arranged in the first concave cavity; the vibration beam layer comprises a vibration beam base body and vibration beam structures, the vibration beam base body is connected to the first side of the pressure sensing film, the vibration beam structures are connected to the vibration beam base body, and the anchor area of at least one vibration beam structure is fixedly connected to the boss; the stress isolation layer is connected to the side, away from the pressure sensing layer, of the vibration beam layer. The substrate layer is connected to the side, away from the vibration beam layer, of the stress isolation layer. The folding structure is formed by the first concave cavity and the second concave cavity of the pressure-sensitive film, so that pressure-sensitive deformation of the pressure-sensitive film can be converted into bending deformation from traditional tension-compression deformation, and the sensitivity of the pressure-sensitive film is improved.

Description

Technical Field

[0001] The present application relates to the field of force measurement technology, and in particular to a sensitive structure of a pressure sensor. Background Art

[0002] As a high-precision and high-stability pressure measurement device, quartz resonant pressure sensor is widely used in industrial production, scientific research and other fields. Its sensitive structure, as the core part of the sensor, plays a decisive role in the performance of the sensor. At present, the sensitive structure of quartz resonant pressure sensor mainly includes all-quartz sensitive structure, metal Bourdon tube + quartz vibration beam structure and other types. These structures have their own characteristics in design, but they also expose some problems in practical applications: 1. The existing metal wave lamp tube + quartz vibration beam structure cannot solve the problem of thermal expansion coefficient matching. Due to the use of multiple materials, the thermal expansion coefficients of the materials themselves cannot be completely matched, and the use of process adhesive bonding cannot effectively guarantee the matching of thermal expansion coefficients, resulting in a relatively large temperature drift coefficient when the temperature changes within the full temperature range; 2. The existing all-quartz sensitive structure adopts a circular structure, which has a large loss at the base, the manufacturing process of the integrated structure is difficult, and the ultra-thin pressure-sensitive film is difficult to process; 3. The existing sensitive structure vibration beam electrode cannot be led out separately, and gold wire bonding is required to lead out the wire. Chip-level micro-assembly is required, which is difficult and inefficient. The gold wire is anchored to the pressure-sensitive film through the vibration beam structure layer. The thermal deformation of the gold wire itself will affect the pressure-sensitive film, thereby causing the vibration beam frequency to drift; 4. The pressure-sensitive membranes of existing sensitive structures are all over-positioned structures, which cannot effectively isolate assembly stress and thermal stress, causing the pressure-sensitive membrane itself to be easily deformed. The contact process between the pressure-sensitive membrane and the external fluid will cause the uniformity of the pressure-sensitive temperature to change. The temperature gradient of the pressure-sensitive membrane itself will also cause vibration beam drift; 5. The existing structure cannot eliminate the common mode error of the vibration beam caused by temperature or packaging stress. The vibration beam changes with temperature and the frequency drifts. The assembly stress also causes the vibration beam to drift in time. As a characteristic of the sensitive structure itself, it cannot be compensated by software, resulting in poor product accuracy. Summary of the invention

[0003] The present application aims to solve at least one of the technical problems existing in the related art. To this end, the present application proposes a pressure sensor sensitive structure.

[0004] A pressure sensor sensitive structure proposed according to an embodiment of the present application includes: The pressure-sensitive layer comprises a pressure-sensitive film, wherein the pressure-sensitive film is provided with a first concave cavity, a second concave cavity and a convex platform, wherein the first concave cavity is provided at a first side of the pressure-sensitive film, the second concave cavity is provided at a second side of the pressure-sensitive film, the first side of the pressure-sensitive film and the second side of the pressure-sensitive film are opposite to each other, and the convex platform is provided in the first concave cavity; A vibration beam layer, the vibration beam layer comprising a vibration beam base and a vibration beam structure, the vibration beam base is connected to the first side of the pressure-sensitive film, the vibration beam structure is connected to the vibration beam base, and at least one anchor area of ​​the vibration beam structure is fixedly connected to the boss; A stress isolation layer connected to a side of the vibration beam layer away from the pressure-sensing layer; The base layer is connected to a side of the stress isolation layer away from the vibration beam layer.

[0005] According to the sensitive structure of the pressure sensor in the embodiment of the present application, a folded structure is formed by the first cavity and the second cavity of the pressure-sensitive membrane, which can transform the pressure-sensitive deformation of the pressure-sensitive membrane from traditional tensile and compressive deformation into bending deformation, thereby improving the sensitivity of the pressure-sensitive membrane. It can also effectively absorb assembly stress and thermal stress. The boss can amplify the deformation of the pressure-sensitive membrane, thereby improving the sensitivity.

[0006] According to one embodiment of the present application, the first cavity and the second cavity are staggered.

[0007] According to one embodiment of the present application, the first cavity and the second cavity have the same depth.

[0008] According to an embodiment of the present application, the pressure-sensitive film is fixedly connected to the vibration beam base through glass slurry, and the pressure-sensitive film is provided with an overflow groove, and the overflow groove is arranged beside the glass slurry.

[0009] According to one embodiment of the present application, the vibration beam structure includes a pressure measuring vibration beam, a reference vibration beam and a matching vibration beam, the anchor area of ​​the pressure measuring vibration beam is fixedly connected to the boss, the anchor area of ​​the reference vibration beam is fixedly connected to the vibration beam base, the matching vibration beam and the reference vibration beam are symmetrically arranged on the vibration beam base with respect to the pressure measuring vibration beam, and the anchor area of ​​the matching vibration beam is fixedly connected to the vibration beam base.

[0010] According to an embodiment of the present application, the pressure measuring vibration beam, the reference vibration beam and the matching vibration beam have the same size.

[0011] According to one embodiment of the present application, the vibration beam structure includes an anchor area, a connecting beam, a node, and a tuning fork vibration beam, the anchor area is connected to the connecting beam, the connecting beam is connected to the node, and the node is connected to the tuning fork vibration beam.

[0012] According to an embodiment of the present application, the stress isolation layer includes a stress isolation ring structure, and the stress isolation ring structure is hollow inside and provided with a through hole.

[0013] According to an embodiment of the present application, the stress isolation ring structure connects the vibration beam layer and the base layer through a bonding glass paste ring.

[0014] According to an embodiment of the present application, the pressure-sensitive film is a quartz crystal pressure-sensitive film, the vibration beam structure is a quartz crystal vibration beam structure, the stress isolation ring structure is a quartz isolation ring structure, and the base layer is a quartz crystal base layer.

[0015] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present application or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a cross-sectional view of the assembly of the sensitive structure of the pressure sensor provided in the embodiment of the present application.

[0018] Figure 2 It is an assembly top view of the pressure sensor sensitive structure provided by an embodiment of the present application without the pressure-sensitive layer.

[0019] Figure 3 It is a schematic diagram of the structure of the pressure-sensitive film provided in the embodiment of the present application.

[0020] Figure 4 yes Figure 3 A schematic diagram of the cross-sectional structure of the pressure-sensitive film provided in the embodiment as viewed along line A.

[0021] Figure 5 It is a schematic diagram of the structure of the stress isolation layer provided in an embodiment of the present application.

[0022] Figure 6 yes Figure 5 A schematic diagram of the cross-sectional structure of the stress isolation layer in the B direction provided in the embodiment.

[0023] Figure 7 It is a schematic diagram of the structure of the base layer provided in an embodiment of the present application.

[0024] Figure 8 yes Figure 7 A schematic diagram of the C-direction cross-sectional structure of the base layer provided in the embodiment.

[0025] Fig. 9 It is a schematic diagram of the dimensions of the vibration beam structure provided in the embodiment of the present application.

[0026] Reference numerals: 100, pressure-sensitive layer; 110, pressure-sensitive film; 111, first concave cavity; 112, second concave cavity; 113, boss; 114, overflow groove; 200, vibration beam layer; 210, vibration beam base; 220, vibration beam structure; 221, pressure measuring vibration beam; 222, reference vibration beam; 223, matching vibration beam; 224, first excitation electrode; 225, second excitation electrode; 226, anchor area; 227, connecting beam; 228, wave node; 229, tuning fork vibration beam; 230, folding beam; 300, stress isolation layer; 310, stress isolation ring structure; 311, through hole; 400, base layer; 410, quartz base plate; 420, coating getter layer. DETAILED DESCRIPTION

[0027] The following is a further detailed description of the implementation of the present application in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but cannot be used to limit the scope of the present application.

[0028] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0029] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection, wherein the fixed connection can include an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0030] In the embodiments of the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0032] Combine the following Figures 1 to 9 The sensitive structure of the pressure sensor of the present application is described.

[0033] According to an embodiment of the present application, a pressure sensor sensitive structure (hereinafter referred to as a sensitive structure) is proposed. The sensitive structure includes a pressure sensing layer 100 , a vibration beam layer 200 , a stress isolation layer 300 and a base layer 400 . The pressure-sensitive layer 100 includes a pressure-sensitive film 110, and the pressure-sensitive film 110 is provided with a first cavity 111, a second cavity 112 and a boss 113. The first cavity 111 is provided on a first side of the pressure-sensitive film 110, and the second cavity 112 is provided on a second side of the pressure-sensitive film 110. The first side of the pressure-sensitive film 110 and the second side of the pressure-sensitive film 110 are opposite to each other, and the boss 113 is provided in the first cavity 111; the vibration beam layer 200 includes a vibration beam base 210 and a vibration beam structure 220. The vibration beam base 210 is connected to the first side of the pressure-sensitive film 110, and the vibration beam structure 220 is connected to the vibration beam base 210. An anchor area 226 of at least one vibration beam structure 220 is fixedly connected to the boss 113; the stress isolation layer 300 is connected to a side of the vibration beam layer 200 away from the pressure-sensitive layer 100; and the base layer 400 is connected to a side of the stress isolation layer 300 away from the vibration beam layer 200.

[0034] According to the sensitive structure of the pressure sensor in the embodiment of the present application, a folded structure is formed by the first cavity 111 and the second cavity 112 of the pressure-sensitive film 110, which can transform the pressure-sensitive deformation of the pressure-sensitive film 110 from traditional tensile and compressive deformation into bending deformation, thereby improving the sensitivity of the pressure-sensitive film 110, and can also effectively absorb assembly stress and thermal stress. The boss 113 can amplify the deformation of the pressure-sensitive film 110, thereby improving the sensitivity.

[0035] It is understandable that the pressure-sensitive film 110 is designed with a first cavity 111, a second cavity 112 and a boss 113. The boss 113 is arranged in the first cavity 111, and the two together constitute a stress isolation groove structure. During the assembly process, due to the existence of assembly stress, the over-positioned pressure-sensitive film 110 may be twisted and deformed, and the pressure-sensitive film 110 with the first cavity 111 can effectively absorb the assembly stress; when the sensitive structure is tested at high and low temperatures, the thermal stress will cause the pressure-sensitive film 110 to be twisted and deformed, and the first cavity 111 can effectively absorb the thermal stress; fourth, the boss 113 can amplify the deformation of the pressure-sensitive film 110, thereby improving the resistance to temperature change and overload. In one embodiment, the pressure-sensitive film 110 is fixedly connected to the vibration beam base 210 by glass slurry.

[0036] The vibration beam base 210 is connected to the portion of the pressure-sensitive layer 100 provided with the first side of the pressure-sensitive film 110, and plays the role of supporting and fixing the vibration beam structure 220. The vibration beam structure 220 is connected to the vibration beam base 210, and at least one anchor area 226 thereof is fixedly connected to the boss 113. The vibration beam structure 220 will vibrate when affected by the deformation of the pressure-sensitive film 110, and its vibration frequency is related to the pressure.

[0037] The stress isolation layer 300 is connected to the side of the vibration beam layer 200 away from the pressure-sensing layer 100, and its main function is to isolate the influence of external stress on the vibration beam layer 200 and protect the stability and accuracy of the vibration beam structure 220. It can be understood that the stress isolation layer 300 can effectively weaken the assembly stress, thermal stress and vibration impact stress from the package, and improve the stability of the zero bias of the whole table.

[0038] The base layer 400 is connected to the side of the stress isolation layer 300 facing away from the vibration beam layer 200 to provide support and stability for the entire sensitive structure.

[0039] According to an embodiment of the present application, the first cavity 111 and the second cavity 112 are staggered. It can be understood that the first cavity 111 is located on one side of the pressure-sensitive film 110, and the second cavity 112 is located on the opposite side of the pressure-sensitive film 110. The first cavity 111 and the second cavity 112 are staggered to form a folded structure of bending deformation, thereby enhancing the deformation effect of the pressure-sensitive film 110.

[0040] According to an embodiment of the present application, the first cavity 111 and the second cavity 112 have the same depth. It is understandable that the first cavity 111 and the second cavity 112 have the same depth, and this design helps to maintain uniform deformation of the pressure-sensitive film 110 when subjected to force, thereby improving measurement accuracy.

[0041] According to an embodiment of the present application, the pressure-sensitive film 110 is fixedly connected to the vibration beam base 210 through glass slurry, and the pressure-sensitive film 110 is provided with an overflow groove 114, and the overflow groove 114 is arranged beside the glass slurry. It can be understood that the overflow groove 114 is arranged beside the glass slurry, which can provide a channel for excess slurry to flow out during the curing process of the glass slurry, so as to avoid the overflow of slurry affecting the stability and accuracy of the structure. At the same time, the overflow groove 114 can also alleviate the thermal stress caused by temperature changes to a certain extent, thereby improving the reliability of the sensor.

[0042] According to an embodiment of the present application, the depth of the first cavity 111 is the same as the height of the boss 113. It can be understood that the first cavity 111 and the boss 113 cooperate to form a stress isolation groove structure, wherein the depth of the first cavity 111 and the height of the boss 113 are the same to ensure that the boss 113 does not protrude too much from the pressure-sensitive layer 100 to the vibration beam layer 200.

[0043] According to one embodiment of the present application, the vibration beam structure 220 includes a pressure measuring vibration beam 221, a reference vibration beam 222 and a matching vibration beam 223. The anchor area 226 of the pressure measuring vibration beam 221 is fixedly connected to the boss 113, the anchor area 226 of the reference vibration beam 222 is fixedly connected to the vibration beam base 210, the matching vibration beam 223 and the reference vibration beam 222 are symmetrically arranged on the vibration beam base 210 with respect to the pressure measuring vibration beam 221, and the anchor area 226 of the matching vibration beam 223 is fixedly connected to the vibration beam base 210.

[0044] The vibration beam layer 200 includes a vibration beam base 210 and a plurality of vibration beam structures 220, and the anchoring area 226 of the pressure measuring vibration beam 221 is fixedly connected to the boss 113. Since the boss 113 can amplify the deformation of the pressure sensing film 110, the pressure measuring vibration beam 221 can more accurately sense the change in pressure and convert it into an electrical signal for output. The anchoring area 226 of the reference vibration beam 222 is fixedly connected to the vibration beam base 210. The reference vibration beam 222 is used as a reference for comparison with the output signal of the pressure measuring vibration beam 221, thereby eliminating common mode errors and improving the accuracy of the measurement. The matching vibration beam 223 makes the entire vibration beam layer 200 more symmetrical and stable in structure, which helps to reduce the influence of external interference on the measurement results. In addition, the matching vibration beam 223 can also be used as an additional reference vibration beam to further improve the accuracy and reliability of the measurement.

[0045] According to one embodiment of the present application, the pressure measuring vibration beam 221, the reference vibration beam 222 and the matching vibration beam 223 have the same size. It is understandable that the same size of the vibration beam structure 220 helps to reduce the thermal stress and mechanical stress caused by the size difference, thereby improving the stability and reliability of the sensor. The pressure measuring vibration beam 221, the reference vibration beam 222 and the matching vibration beam 223 with the same size are integrated into one process, and the process consistency of the pressure measuring vibration beam 221 and the reference vibration beam 222 is utilized to suppress the common mode error of the pressure sensing vibration beam, thereby reducing and improving the temperature drift coefficient of the sensitive structure as a whole, and effectively isolating the influence of external thermal stress on the tuning fork vibration beam 229, thereby solving the stress isolation problem under high sensitivity conditions. The integrated temperature measuring diode bare DIE can accurately reflect the core temperature of the vibration beam and improve the temperature compensation effect.

[0046] According to one embodiment of the present application, the vibration beam structure 220 includes an anchor area 226, a connecting beam 227, a node 228, and a tuning fork vibration beam 229, wherein the anchor area 226 is connected to the connecting beam 227, the connecting beam 227 is connected to the node 228, and the node 228 is connected to the tuning fork vibration beam 229.

[0047] It is understandable that the vibration beam structure 220 is responsible for converting the mechanical deformation sensed by the pressure-sensitive layer 100 into an electrical signal for output. The anchor area 226 of the vibration beam structure 220 of this embodiment is connected to the connecting beam 227, providing a stable support point for the connecting beam 227. The connecting beam 227 is the connecting part between the anchor area 226 and the node 228. It is responsible for transferring the fixing effect of the anchor area 226 to the node 228 while maintaining the integrity and stability of the structure. The node 228 is located between the connecting beam 227 and the tuning fork vibration beam 229. The design of the node 228 enables the vibration beam to form a specific vibration mode when vibrating, thereby improving the accuracy and stability of the measurement. The tuning fork vibration beam 229 is the vibration part in the vibration beam structure 220, which is responsible for converting the mechanical deformation sensed by the pressure-sensitive layer 100 into an electrical signal for output. In this embodiment, the tuning fork vibration beam 229 is connected to the wave node 228, and the external force is transmitted to the tuning fork vibration beam 229 through the vibration of the wave node 228, thereby realizing the output of the vibration signal.

[0048] According to an embodiment of the present application, the first excitation electrodes 224 of the two reference vibration beams are led out by routing on the vibration beam base 210. In this embodiment, the first excitation electrodes 224 of the two reference vibration beams are led out by routing on the vibration beam base 210. This design not only simplifies the electrode lead-out process, but also reduces the manufacturing cost. At the same time, since the first excitation electrode 224 of the reference vibration beam is directly connected to the vibration beam base 210, it can more accurately reflect the real state of the vibration beam, thereby improving the accuracy of the measurement.

[0049] According to an embodiment of the present application, the vibration beam layer 200 includes a folded beam 230, and the second excitation electrode 225 of the pressure measuring vibration beam is electrically led out through the folded beam 230. The folded beam 230 achieves compactness and lightness of the vibration beam structure 220 by folding a part of the vibration beam. At the same time, the folded beam 230 also serves as an electrical lead-out path for the second excitation electrode 225 of the pressure measuring vibration beam. This design not only simplifies the electrode lead-out process, but also improves the overall rigidity and stability of the vibration beam structure 220.

[0050] According to an embodiment of the present application, the number of bosses 113 corresponds to the number of anchor areas 226 of the pressure measuring vibration beam 221 . The number of anchor areas 226 of the pressure measuring vibration beam 221 is two, and the anchor areas 226 of the two pressure measuring vibration beams 221 are arranged at intervals.

[0051] The number of bosses 113 is set corresponding to the number of anchoring areas 226 of the pressure measuring vibration beam 221. In this embodiment, the number of anchoring areas 226 of the pressure measuring vibration beam 221 is two, so the number of bosses 113 is also two. The two bosses 113 are arranged at intervals, providing a stable support point for the anchoring area 226 of the pressure measuring vibration beam 221. The anchoring areas 226 of the two pressure measuring vibration beams 221 are arranged at intervals, so that the pressure measuring vibration beam 221 can better sense the deformation of the pressure sensing film 110.

[0052] According to an embodiment of the present application, the stress isolation layer 300 includes a stress isolation ring structure 310 , and the stress isolation ring structure 310 is hollow and has a through hole 311 therein.

[0053] When the sensitive structure is bonded to the TO tube shell or LCC ceramic tube shell base, the thermal expansion coefficients of the tube shell material and the quartz material do not match, resulting in assembly stress. The stress isolation ring structure 310 can effectively isolate the assembly stress. The stress isolation ring structure 310 can be used to protect the vibration beam layer 200; adding a stress isolation layer 300 between the base layer 400 and the vibration beam layer 200 can provide a second level of "blocking" of the thermal stress of the external tube shell.

[0054] The through hole 311 can reduce the thermal expansion coefficient of the stress isolation ring structure 310 , making its dimensional changes at different temperatures more stable.

[0055] According to an embodiment of the present application, the stress isolation ring structure 310 connects the vibration beam layer 200 and the base layer 400 through a bonding glass paste ring.

[0056] According to an embodiment of the present application, the pressure-sensitive film 110 is a quartz crystal pressure-sensitive film 110 , the vibration beam structure 220 is a quartz crystal vibration beam structure 220 , the stress isolation ring structure 310 is a quartz isolation ring structure, and the base layer 400 is a quartz crystal base layer 400 .

[0057] According to an embodiment of the present application, the anchor region 226 of the pressure measuring vibration beam 221 is fixedly connected to the boss 113 by an adhesive material, and the adhesive material is at least one of glass paste, metal solder, epoxy glue and gold-gold bonding material.

[0058] According to an embodiment of the present application, the base layer 400 includes a quartz base plate 410 and a film-coated getter layer 420, the film-coated getter layer 420 is connected to the quartz base plate 410, the quartz base plate 410 is connected to the stress isolation ring structure 310, and the film-coated getter layer 420 is arranged on the side of the quartz base plate 410 close to the stress isolation ring structure 310. The film-coated getter layer 420 is provided with a getter, and the getter can absorb the surrounding gas when activated.

[0059] It is understandable that a coated getter layer 420 is provided at the bottom of the through hole 311 of the stress isolation ring structure 310, and the coated getter layer 420 is activated at the same time at the hot pressing bonding temperature to achieve long-term maintenance of high vacuum and ensure that the quartz resonator has a higher quality factor.

[0060] In one embodiment, the sensitive structure adopts a full quartz sensitive structure solution; the pressure-sensitive film 110, the vibration beam structure 220, the stress isolation ring and the base layer 400 are all made of quartz crystal materials, which improves the matching of the thermal expansion coefficient of the material, solves the temperature drift problem caused by the mismatch of the thermal expansion coefficient of the material, and replaces the traditional single-part processing method.

[0061] In one embodiment, the pressure sensor sensitive structure of the present application is described below in conjunction with an embodiment.

[0062] This embodiment uses a full quartz vibration beam structure 220 with temperature compensation, and the overall structure is as follows: Figure 4 As shown, the entire sensitive structure includes four layers: a pressure-sensitive layer 100 , a vibration beam layer 200 , a stress isolation layer 300 and a base layer 400 .

[0063] First, the pressure-sensitive layer 100 and the vibration beam layer 200 are aligned and pre-fixed at the wafer level through glass slurry, and wafer-level bonding is achieved under vacuum conditions, with a bonding temperature of 400 degrees, a holding time of 15 minutes, a load of 500kg, and a bonding vacuum of 1E-3Pa; secondly, the three-layer structure of the pressure-sensitive layer 100 + vibration beam layer 200 combination sheet, the stress isolation layer 300, and the base layer 400 is aligned and pre-fixed at the wafer level, and the three-layer alignment accuracy is ±10um; under vacuum conditions, the three-layer wafer-level bonding and getter activation are achieved, with a bonding temperature of 390 degrees, a holding time of 15 minutes, a load of 500kg, and a bonding vacuum of 1E-3Pa; Remove the sensitive structure of the pressure-sensitive layer 100 Figure 5As shown, the entire vibration beam structure 220 includes a pressure measuring vibration beam 221, a reference vibration beam 222 and a matching vibration beam 223. The anchor area 226 of the pressure measuring vibration beam 221 is rigidly connected to the boss 113 of the pressure sensitive film 110 through glass slurry, directly sensing the stress and strain of the pressure sensitive film 110, and the excitation electrode of the pressure measuring vibration beam 221 is electrically led out through the folding beam 230; the anchor area 226 of the reference vibration beam 222 is rigidly connected to the frame of the vibration beam layer 200 as an integrated whole, so that the reference vibration beam 222 is not affected by the stress and strain of the pressure sensitive film 110, and the two excitation electrodes of the reference vibration beam 222 are led out through wiring on the vibration beam layer 200, and a lead-free connection is realized inside the structure. The matching vibration beam 223 is mainly used to realize the structural symmetry of the vibration beam layer 200.

[0064] The pressure-sensitive layer 100 is made of a 3-inch quartz wafer cut from z0, and the structure is as follows: Figure 6 As shown, the thickness of the film is 220um~1920um, the pressure-sensitive film 110 includes a first cavity 111, a second cavity 112, a boss 113 and a slurry overflow groove 114, the top and bottom layers of the pressure-sensitive film 110 are simultaneously sandblasted, wet-etched or laser-processed, and the angle between the side edge of the structure and the wafer is thet1, and the value range is: 45 degrees~75 degrees, so that the depth of the bottom cavity layer is equal to the height of the top boss 113 layer, and the thickness of the pressure-sensitive film 110 determines the range of the sensitive structure , the design thickness is 108um~500um, and the measuring range is 100kPa~50.1MPa; the height of the quartz boss 113 is 50um, and the quartz boss 113 plays the role of amplifying the strain of the pressure-sensitive film 110, thereby improving the pressure sensitivity of the pressure-sensitive film 110, and the back cavity and the front cavity form a folded pressure-sensitive film 110 structure. The recommended dimensions are shown in Table 1, and the thickness of the pressure-sensitive layer 100 and the pressure-sensitive film 110 under different measuring ranges are shown in Table 2.

[0065] The stress isolation layer 300 is made of a 3-inch quartz wafer cut from z0, and the structure is as follows: Figure 7 As shown, it includes a stress isolation ring structure 310 and a double-sided bonding glass slurry ring. The width of the bonding slurry ring is 0.5 mm. The cavity ring is processed by double-sided sandblasting, double-sided laser grooving or double-sided wet etching. The angle between the edge of the processed structure and the wafer plane is thet2, with a value range of 45 degrees to 75 degrees. The recommended dimensions are shown in Table 3.

[0066] The base layer 400 is made of a 3-inch quartz wafer cut from z0, and the structure is as follows: Figure 8 As shown, it includes a quartz substrate 410 and a coated getter layer 420. A hard shielding plate process is used to sputter a non-evaporable metal film getter at the bottom of the cavity using magnetron sputtering technology. The main component of the target material is titanium-zirconium alloy. The specific dimensions of the substrate layer 400 structure are shown in Table 4.

[0067] The vibration beam layer 200 is made of a 3-inch quartz wafer cut from z0, and the internal structure is as follows: Fig. 9 As shown, the vibration beam structure 220 includes three types of pressure measuring vibration beams 221, a reference vibration beam 222 and a matching vibration beam 223. The basic dimensions of the three vibration beam structures 220 are exactly the same, and the entire structure is axially symmetrical. Each quartz vibration beam structure 220 includes four parts: an anchor area 226, a connecting beam 227, a wave node 228, and a tuning fork vibration beam 229; the anchor area E and the anchor area F of the pressure measuring vibration beam 221 are rigidly connected to the upper surface of the boss 113 of the folding pressure sensing film 110 through glass slurry to sense the pressure changes input from the outside; the anchor area A and the anchor area B of the reference vibration beam 222 are rigidly connected to the vibration beam layer 200 frame, and have the same temperature characteristics as the pressure measuring vibration beam 221 when not sensing the external input pressure. The frequencies of the two vibration beams are subtracted, and the common mode suppression function is realized through the frequency difference output; the matching vibration beam 223 mainly realizes the symmetry of the vibration beam layer 200 structure, and its anchor area C and the anchor area D are rigidly connected to the vibration beam layer 200 frame; When the input pressure of the pressure-sensitive film 110 in the normal direction increases, the strain of the pressure-sensitive film 110 causes the relative position of the two quartz islands on the pressure-sensitive film 110 to increase, and the axial tensile stress of the pressure-sensitive vibration beam anchored thereto increases, causing the resonance frequency of the tuning fork to increase. When the input pressure of the pressure-sensitive film 110 in the normal direction decreases, the strain of the pressure-sensitive film 110 causes the relative position of the two quartz islands on the pressure-sensitive film 110 to decrease, and the axial tensile stress of the pressure-sensitive vibration beam anchored thereto decreases, causing the resonance frequency of the tuning fork to decrease. The strain of the pressure-sensitive film 110 causes the axial pressure of the tuning fork resonance, and the resonance frequency of the tuning fork resonance plane differential mode caused by the pressure-sensitive film 110 is as follows: (1) here, To measure the axial tensile stress felt by the pressure vibration beam, is the eigenresonant frequency of the reference beam, is the Euler constant of the tuning fork beam, where and The expression is as follows: (2) (3) here, is the elastic modulus of the quartz beam, is the density of quartz, , and is the length, width and thickness of a single beam of the tuning fork vibration beam. The recommended resonant frequency of the vibration beam is 115kHz~125kHz, and the recommended quality factor Q is 12000~19000; the vibration beam is an axisymmetric structure, symmetrical along the x-axis.

[0068] In order to improve the symmetry of the sensitive structure, a counterweight vibration beam is added, and the structural dimensions of the reference vibration beam 222 and the pressure measuring vibration beam 221 are exactly the same. Therefore, the vibration beam has a pressure measuring tuning fork vibration beam, a reference tuning fork vibration beam and a counterweight tuning fork vibration beam. The thickness of the vibration beam layer 200 is 80um~90um, the width of the wiring electrode is 30um, and the recommended structural dimensions are shown in Table 5.

[0069] It should be noted that this solution can be extended to high-precision quartz resonant accelerometers or high-precision silicon resonant accelerometers. Using an all-quartz solution to replace the traditional solution can effectively improve the consistency of the sensitive structure and facilitate mass production; Table 1 Quartz pressure-sensitive membrane structural dimension parameters (unit: um)

[0070] Table 2 Correspondence between quartz pressure-sensitive film and measuring range (unit: um)

[0071] Table 3 Quartz transition ring structural dimension parameters (unit: um)

[0072] Table 4 Quartz substrate structure size parameters (unit: um)

[0073] Table 5 Quartz vibration beam structure size parameters (unit: um)

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A pressure sensor sensitive structure, characterized in that: include: The pressure-sensitive layer (100) comprises a pressure-sensitive film (110), wherein the pressure-sensitive film (110) is provided with a first concave cavity (111), a second concave cavity (112) and a convex platform (113), wherein the first concave cavity (111) is provided on a first side of the pressure-sensitive film (110), the second concave cavity (112) is provided on a second side of the pressure-sensitive film (110), the first side of the pressure-sensitive film (110) and the second side of the pressure-sensitive film (110) are opposite to each other, and the convex platform (113) is provided in the first concave cavity (111); A vibration beam layer (200), the vibration beam layer (200) comprising a vibration beam base (210) and a vibration beam structure (220), the vibration beam base (210) being connected to a first side of the pressure-sensitive film (110), the vibration beam structure (220) being connected to the vibration beam base (210), and at least one anchor region (226) of the vibration beam structure (220) being fixedly connected to the boss (113); A stress isolation layer (300) connected to a side of the vibration beam layer (200) facing away from the pressure sensing layer (100); The base layer (400) is connected to a side of the stress isolation layer (300) that is away from the vibration beam layer (200).

2. The pressure sensor sensitive structure according to claim 1, characterized in that: The first concave cavity (111) and the second concave cavity (112) are arranged in a staggered manner.

3. The pressure sensor sensitive structure according to claim 1, characterized in that: The first concave cavity (111) and the second concave cavity (112) have the same depth.

4. The pressure sensor sensitive structure according to claim 1, characterized in that: The pressure-sensitive film (110) is fixedly connected to the vibration beam base (210) via glass paste, and the pressure-sensitive film (110) is provided with an overflow groove (114), and the overflow groove (114) is arranged beside the glass paste.

5. The pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The vibration beam structure (220) comprises a pressure measuring vibration beam (221), a reference vibration beam (222) and a matching vibration beam (223); the anchor region (226) of the pressure measuring vibration beam (221) is fixedly connected to the boss (113); the anchor region (226) of the reference vibration beam (222) is fixedly connected to the vibration beam base (210); the matching vibration beam (223) and the reference vibration beam (222) are symmetrically arranged on the vibration beam base (210) with respect to the pressure measuring vibration beam (221); and the anchor region (226) of the matching vibration beam (223) is fixedly connected to the vibration beam base (210).

6. The pressure sensor sensitive structure according to claim 5, characterized in that: The pressure measuring vibration beam (221), the reference vibration beam (222), and the matching vibration beam (223) have the same size.

7. The pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The vibration beam structure (220) comprises an anchor region (226), a connecting beam (227), a wave node (228), and a tuning fork vibration beam (229); the anchor region (226) is connected to the connecting beam (227), the connecting beam (227) is connected to the wave node (228), and the wave node (228) is connected to the tuning fork vibration beam (229).

8. The pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The stress isolation layer (300) comprises a stress isolation ring structure (310), and the stress isolation ring structure (310) is hollow inside and provided with a through hole (311).

9. The pressure sensor sensitive structure according to claim 8, characterized in that: The stress isolation ring structure (310) connects the vibration beam layer (200) and the base layer (400) via a bonding glass slurry ring.

10. The pressure sensor sensitive structure according to claim 8, characterized in that: The pressure-sensitive film (110) is a quartz crystal pressure-sensitive film (110), the vibration beam structure (220) is a quartz crystal vibration beam structure (220), the stress isolation ring structure (310) is a quartz isolation ring structure, and the base layer (400) is a quartz crystal base layer (400).

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