A pressure sensor sensitive structure

Abstract

The present application relates to the field of force measurement technology, and provides a pressure sensor sensitive structure, which includes a pressure-sensitive layer, a vibration beam layer and a base layer. The pressure-sensitive layer includes a pressure-sensitive film, and the pressure-sensitive film is provided with a first cavity and a boss, and the boss is provided in the first cavity, and the first cavity and the boss form a stress isolation groove structure; the vibration beam layer includes a vibration beam base and a plurality of vibration beam structures, and the vibration beam base is connected to a side of the pressure-sensitive layer provided with a first cavity, and the vibration beam structure is connected to the vibration beam base, and the vibration beam structure includes a pressure-measuring vibration beam and a reference vibration beam, and the anchor area of ​​the pressure-measuring vibration beam is fixedly connected to the boss, and the anchor area of ​​the reference vibration beam is fixedly connected to the vibration beam base; the base layer is connected to the vibration beam layer, and the vibration beam layer is provided between the pressure-sensitive layer and the base layer. Through the first cavity and the boss of the pressure-sensitive film, the assembly stress and thermal stress can be effectively absorbed, and the possibility of distortion and deformation of the pressure-sensitive film can be reduced, and the boss can amplify the deformation of the pressure-sensitive film.

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:

[0003] 1. 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;

[0004] 2. 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, and the anti-vibration ability is weak;

[0005] 3. The existing metal Bourdon 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 poor temperature change resistance when the temperature changes within the full temperature range;

[0006] 4. 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. As a characteristic of the sensitive structure itself, it cannot be compensated by software, resulting in poor vibration and impact resistance of the product.

[0007] 5. 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, thereby affecting the structure's resistance to temperature change and overload performance.

[0008] In summary, the sensitive structure of the current quartz resonant pressure sensor has technical problems in manufacturing process, electrode lead-out, material matching, common mode error elimination, and pressure-sensitive film stress isolation, and further research and development and optimization are needed to improve the performance and stability of the sensor. Summary of the invention

[0009] 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.

[0010] The pressure sensor sensitive structure proposed in the embodiment of the present application includes:

[0011] The pressure-sensitive layer comprises a pressure-sensitive film, wherein the pressure-sensitive film is provided with a first cavity and a boss, wherein the boss is provided in the first cavity, and the first cavity and the boss form a stress isolation groove structure;

[0012] A vibration beam layer, the vibration beam layer comprising a vibration beam base and a plurality of vibration beam structures, the vibration beam base being connected to a side of the pressure-sensing layer provided with the first concave cavity, the vibration beam structure being connected to the vibration beam base, the vibration beam structure comprising a pressure-measuring vibration beam and a reference vibration beam, the anchor region of the pressure-measuring vibration beam being fixedly connected to the boss, and the anchor region of the reference vibration beam being fixedly connected to the vibration beam base;

[0013] The base layer is connected to the vibration beam layer, and the vibration beam layer is arranged between the pressure-sensitive layer and the base layer.

[0014] According to the sensitive structure of the pressure sensor in the embodiment of the present application, the first cavity and the boss of the pressure-sensitive membrane can effectively absorb assembly stress and thermal stress, reduce the possibility of distortion of the pressure-sensitive membrane, and the boss can amplify the deformation of the pressure-sensitive membrane, thereby improving the ability to resist temperature changes and overloads.

[0015] According to an embodiment of the present application, the first excitation electrode of the reference vibration beam is led out by routing on the vibration beam base.

[0016] According to an embodiment of the present application, the vibration beam layer includes a folded beam, and the second excitation electrode of the pressure measuring vibration beam is electrically led out through the folded beam.

[0017] According to an embodiment of the present application, the vibration beam structure includes a matching vibration beam, 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.

[0018] According to an embodiment of the present application, the number of the bosses is set corresponding to the number of the anchor areas of the pressure measuring vibration beam. The number of the anchor areas of the pressure measuring vibration beam is two, and the anchor areas of the two pressure measuring vibration beams are arranged at intervals.

[0019] 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.

[0020] According to an embodiment of the present application, the pressure-sensitive film is a quartz crystal pressure-sensitive film, the pressure-measuring vibration beam is a quartz crystal pressure-measuring vibration beam, the reference vibration beam is a quartz crystal reference vibration beam, and the base layer is a quartz crystal base layer.

[0021] According to an embodiment of the present application, the anchor area of ​​the pressure measuring vibration beam is fixedly connected to the boss by an adhesive material, and the adhesive material is one of glass paste, metal solder, epoxy glue and gold-gold bonding material.

[0022] According to an embodiment of the present application, the base layer is provided with a second cavity, and the second cavity opens toward the vibration beam layer.

[0023] 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

[0024] 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.

[0025] 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.

[0026] 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.

[0027] Figure 3 Schematic diagram of the structure of the pressure-sensitive film provided in the embodiment of the present application.

[0028] 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.

[0029] Figure 5 It is a schematic diagram of the structure of the base layer provided in an embodiment of the present application.

[0030] Figure 6 yes Figure 5 A schematic diagram of the cross-sectional structure of the substrate layer in the B direction provided in the embodiment.

[0031] Figure 7 It is a schematic diagram of the dimensions of the vibration beam structure provided in the embodiment of the present application.

[0032] Figure 8It is a structural schematic diagram of a screen-printed wafer with a CCD alignment mark provided in an embodiment of the present application.

[0033] Fig. 9 It is a schematic diagram of the dimensions of the screen printing alignment mark provided in the embodiment of the present application.

[0034] Fig.10 It is a schematic diagram of the dimensions of the wafer-level alignment mark provided in an embodiment of the present application.

[0035] Fig.11 It is a schematic diagram of the dimensions of the unit slurry ring provided in the embodiment of the present application.

[0036] Fig.12 It is a structural schematic diagram of screen printing of glass paste for the pressure-sensitive membrane structure layer provided in an embodiment of the present application.

[0037] Fig.13 It is a structural schematic diagram of the first wafer-level vacuum sintering provided in an embodiment of the present application.

[0038] Fig.14 It is a structural schematic diagram of the second wafer-level integrated vacuum sintering provided in an embodiment of the present application.

[0039] Fig.15 It is a schematic diagram of the steps of a sensitive packaging method of a quartz resonant pressure sensor provided in an embodiment of the present application.

[0040] Reference numerals:

[0041] 100, pressure-sensitive layer; 110, pressure-sensitive film; 111, first concave cavity; 112, boss; 113, overflow groove;

[0042] 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;

[0043] 300. Base layer; 310. Second concave cavity. DETAILED DESCRIPTION

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] According to the pressure sensor sensitive structure proposed in the embodiment of the present application (hereinafter referred to as the sensitive structure), please refer to Figures 1 to 4The sensitive structure includes a pressure-sensitive layer 100, a vibration beam layer 200 and a base layer 300. The pressure-sensitive layer 100 includes a pressure-sensitive film 110. The pressure-sensitive film 110 is provided with a first cavity 111 and a boss 112. The boss 112 is provided in the first cavity 111. The first cavity 111 and the boss 112 form a stress isolation groove structure. The vibration beam layer 200 includes a vibration beam base 210 and a plurality of vibration beam structures 220. The vibration beam base 210 is connected to the pressure-sensitive layer 100. There is one side of the first concave cavity 111, the vibration beam structure 220 is connected to the vibration beam base 210, the vibration beam structure 220 includes a pressure measuring vibration beam 221 and a reference vibration beam 222, the anchor area 226 of the pressure measuring vibration beam 221 is fixedly connected to the boss 112, and the anchor area 226 of the reference vibration beam 222 is fixedly connected to the vibration beam base 210; the base layer 300 is connected to the vibration beam layer 200, and the vibration beam layer 200 is arranged between the pressure sensing layer 100 and the base layer 300.

[0050] According to the sensitive structure of the pressure sensor in the embodiment of the present application, the first cavity 111 in the pressure-sensitive layer 100 can effectively absorb assembly stress and thermal stress, reduce the possibility of distortion of the pressure-sensitive film 110, and amplify the deformation of the pressure-sensitive film 110 through the boss 112, thereby improving the resistance to temperature change and overload.

[0051] It is understandable that the pressure-sensitive film 110 is designed with a first cavity 111 and a boss 112. The boss 112 is disposed 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 subjected to high and low temperature tests, the existing 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 112 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.

[0052] 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 112. Since the boss 112 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 measurement.

[0053] The base layer 300 is connected to the other side of the vibration beam layer 200 to provide stable support for the entire sensitive structure.

[0054] 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.

[0055] 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.

[0056] According to an embodiment of the present application, the vibration beam structure 220 includes a matching vibration beam 223 . 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 . The anchor area 226 of the matching vibration beam 223 is fixedly connected to the vibration beam base 210 .

[0057] It can be understood that the matching vibration beam 223 makes the entire vibration beam layer 200 more symmetrical and stable in structure, which helps to reduce the impact of external interference on the measurement results. In addition, the matching vibration beam 223 can also serve as an additional reference vibration beam to further improve the accuracy and reliability of the measurement.

[0058] According to an embodiment of the present application, the number of bosses 112 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.

[0059] The number of bosses 112 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 112 is also two. The two bosses 112 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.

[0060] 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.

[0061] 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.

[0062] According to an embodiment of the present application, the depth of the first cavity 111 is the same as the height of the boss 112. It can be understood that the first cavity 111 and the boss 112 cooperate to form a stress isolation groove structure, wherein the depth of the first cavity 111 and the height of the boss 112 are the same to ensure that the boss 112 does not protrude too much from the pressure-sensitive layer 100 to the vibration beam layer 200.

[0063] According to an embodiment of the present application, the pressure-sensitive film 110 is a quartz crystal pressure-sensitive film 110 , the pressure-measuring vibration beam 221 is a quartz crystal pressure-measuring vibration beam 221 , the reference vibration beam 222 is a quartz crystal reference vibration beam 222 , and the base layer 300 is a quartz crystal base layer 300 .

[0064] 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 112 by an adhesive material, and the adhesive material is one of glass paste, metal solder, epoxy glue and gold-gold bonding material.

[0065] According to an embodiment of the present application, the base layer 300 is provided with a second cavity 310, and the second cavity 310 opens toward the vibration beam layer 200. It can be understood that the base layer 300 structure with the second cavity 310 in this embodiment can effectively weaken the assembly stress, thermal stress and vibration impact stress from the package, and improve the overload resistance and vibration impact resistance of the whole table.

[0066] The sensitive structure of the pressure sensor of the present application is described below in conjunction with an embodiment.

[0067] This technical solution adopts a full quartz vibration beam structure 220 with temperature compensation, and the overall structure is as follows Figure 1 As shown, the entire pressure sensor sensitive structure includes a three-layer structure: a pressure-sensitive layer 100 , a vibration beam layer 200 and a base layer 300 .

[0068] Remove the sensitive structure of the pressure-sensitive layer 100 Figure 2 As 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 112 of the pressure sensitive film 110 through glass slurry, so that the pressure measuring vibration beam 221 can directly sense the stress and strain of the pressure sensitive film 110, and the second excitation electrode 225 of the pressure measuring vibration beam is electrically led out through the folding beam 230; the anchor area 226 of the reference vibration beam 222 is rigidly connected to the vibration beam base 210 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 first excitation electrodes 224 of the two reference vibration beams are led out by routing 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.

[0069] The pressure-sensitive film 110 of the pressure-sensitive layer 100 is made of a z-cut 3-inch quartz wafer, and the structure is as follows: Figure 3 and Figure 4 As shown, the sheet thickness is 220um~1920um, the pressure-sensitive film 110 includes a first cavity 111, a boss 112 and an overflow groove 113, the bottom layer of the pressure-sensitive film 110 is processed by sandblasting, wet etching or laser processing, the angle between the structural side edge and the wafer is thtet1, and the value range is: 45 degrees~75 degrees, the depth from the top of the first groove to the bottom layer is equal to the height from the bottom of the boss 112 to the top layer, the thickness of the pressure-sensitive film 110 determines the range of the sensitive structure, the design thickness is 108um~500um, and the range is 100kPa~50.1MPa; the height of the boss 112 is 50um, and the boss 112 plays a role in amplifying the strain of the pressure-sensitive film 110, thereby improving the pressure sensitivity of the pressure-sensitive film 110, the cavity and the boss 112 form a stress isolation groove structure, which can effectively improve the vibration resistance, the recommended dimensions are shown in Table 1, and the thickness of the pressure-sensitive layer 100 and the thickness of the pressure-sensitive film 110 under different ranges are shown in Table 2.

[0070] Table 1 Quartz pressure-sensitive membrane structural dimension parameters (unit: um)

[0071]

[0072] Table 2 Correspondence between quartz pressure-sensitive film and measuring range (unit: um)

[0073]

[0074] The base layer 300 is made of a z-cut 3-inch quartz wafer, and the structure is as follows: Figure 5 and Figure 6 As shown, the base layer 300 is mainly a quartz base plate, and a hard shielding plate process is adopted. The specific dimensions of the base layer 300 structure are shown in Table 3.

[0075] Table 3 Quartz substrate layer structural dimension parameters (unit: um)

[0076]

[0077] The vibration beam layer 200 is made of a z-cut 3-inch quartz wafer, and the internal structure is as follows: Figure 2 and Figure 7 As shown, there are three types of vibration beam structures 220, including a pressure measuring vibration beam 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 112 of the pressure sensing film 110 through glass slurry to sense the pressure change of external input; the anchor area A and the anchor area B of the reference vibration beam 222 are rigidly connected to the vibration beam base 210, and have the same temperature characteristics as the pressure measuring vibration beam 221 without 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 base 210.

[0078] 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 bosses 112 on the pressure-sensitive film 110 to increase, and the axial tensile stress of the pressure-sensing vibration beam 221 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 bosses 112 on the pressure-sensitive film 110 to decrease, and the axial tensile stress of the pressure-sensing 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:

[0079] (1)

[0080] 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:

[0081] (2)

[0082] (3)

[0083] 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.

[0084] 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 4.

[0085] Table 4 Quartz vibration beam structure size parameters (unit: um)

[0086]

[0087] The technical solution of the present application is further described below in conjunction with a packaging process of a pressure sensor sensitive structure according to an embodiment:

[0088] A packaging method for a sensitive structure of a pressure sensor includes: step 100, step 200 and step 300.

[0089] Step 100: Prepare a screen printing plate, wherein the screen printing plate includes two pairs of screen printing marks, a pair of wafer-level alignment marks, and 40 slurry units, wherein the screen printing marks, the wafer-level alignment marks, and the slurry units are arranged according to preset positions. Fig. 9 As shown), wafer-level alignment marks (such as Fig.10 as shown) and slurry units (as Fig.11 The shape, size and position dimensions of the Figure 8 As shown, the dimensions are shown in Table 5.

[0090] In step 100, during the preparation of the screen printing plate, the thickness of the photosensitive resin of the screen plate needs to be controlled between 35um and 50um. The screen frame material is cast aluminum with a specification of 320mm 320mm. The screen uses stainless steel screen or nylon screen, the mesh number is between 150 and 250 mesh, and the thickness of the photosensitive glue is accurate to 35um±1um. In addition, the viscosity of the high-temperature glass slurry needs to be controlled at 80~100Pa.s, the mesh number is 250~300 mesh, and the sintering temperature is set at 400~450 degrees.

[0091] Step 200, screen printing of the pressure-sensitive layer 100 wafer, including: processing screen printing marks and wafer-level alignment marks in advance on the wafer through high-precision laser marking, wet etching or dry etching process, covering with transparent film, forming a cross-shaped alignment mark on the wafer through screen printing, using two CCD electronic marks to clamp the wafer, after determining the position, putting the formal film into the suction cup and sucking it, adjusting the workbench so that the cross mark on the wafer coincides with the electronic mark, after the pressure-sensitive layer 100 is printed, the wafer needs to stand on the platform for a first preset time to allow the slurry to level to form a pressure-sensitive film 110; wherein, when the wafer is subjected to high-precision laser marking, wet etching or dry etching process, the pressure-sensitive film 110 is formed with a first cavity 111 and a boss 112.

[0092] In the step of screen printing the pressure-sensitive layer wafer, the pressure-sensitive layer uses a 3-8 inch z-cut quartz crystal as the wafer, the thickness of the wafer is between 158um and 1800um, the first preset time is 3-5 minutes, the slurry printing width is 400um-500um, and the slurry layer thickness is 25-30um.

[0093] Step 300, wafer-level bonding of the pressure-sensitive layer 100 and the vibration beam layer 200, includes: using glass slurry to align and pre-fix the pressure-sensitive layer 100 and the vibration beam layer 200 at the wafer level, and performing wafer-level bonding under vacuum conditions to form a vibration-sensing assembly sheet, wherein the anchor area 226 of the pressure-measuring vibration beam 221 of the vibration beam layer 200 and the boss 112 are aligned and pre-fixed.

[0094] In step 300, the alignment accuracy between the pressure-sensitive layer 100 and the vibration beam layer 200 must be controlled within ±10um. The two-layer wafer-level bonding is also performed under vacuum conditions, the bonding temperature is slightly lower at 390 degrees, the holding time is still 15 minutes, the load is maintained at 500kg, and the bonding vacuum is also maintained at 1E-3Pa.

[0095] Step 400 , wafer-level bonding of the vibration-sensing assembly sheet and the base layer 300 , including wafer-level alignment and pre-fixation of the vibration-sensing assembly sheet and the base layer 300 , and wafer-level bonding under vacuum conditions.

[0096] In the step of wafer-level bonding of the vibration-sensing assembly and the base layer, the alignment accuracy needs to be controlled within ±10um. In one embodiment, the bonding temperature is 390 degrees, the holding time is 15 minutes, the load is 500kg, and the bonding vacuum degree is 1E-3Pa.

[0097] Table 5 Sensitive structure packaging structure parameters (unit: um)

[0098]

[0099] It should be noted that this solution uses quartz crystal material as an example, and single crystal silicon material, fused quartz material, functional ceramic material and metal material can also be used.

[0100] It should be noted that the bonding material of the present solution is glass paste, and metal solder, matching epoxy glue or gold-gold bonding material may also be used.

[0101] This solution is suitable for low, medium and high range pressure sensors, and can measure gas, liquid and gas-liquid mixtures. It is used in pressure transmitters, level meters and flow meters. It can be expanded to quartz inertial sensors with high vibration resistance (quartz gyroscopes and quartz accelerometers) and silicon micromechanical inertial sensors with high vibration resistance (silicon microaccelerometers and silicon microgyroscopes).

[0102] It should be noted that the present application adopts a glass paste wafer-level bonding process, which can effectively improve the sealing strength and airtightness, and is conducive to maintaining a high vacuum degree for a long time.

[0103] The pressure sensor sensitive structure of the present application has at least the following advantages:

[0104] (1) The design of a low-temperature drift and high-vibration-resistance pressure-sensitive membrane 110 based on the stress isolation groove effectively reduces the influence of assembly stress, thermal stress and vibration shock on the stress of the pressure-sensitive membrane 110 through the stress isolation groove, and effectively reduces the zero drift of the sensitive structure vibration beam; by designing the boss 112, the strain of the pressure-sensitive membrane 110 caused by the increase in pressure is multiplied into the relative displacement of the two bosses 112, thereby improving the vibration and shock resistance of the pressure-sensitive membrane 110.

[0105] (2) Low-temperature glass paste sealing design based on thermal expansion coefficient matching. The use of low-temperature glass paste sealing that matches the thermal expansion coefficient of quartz crystal improves the bonding strength, air tightness, and electrical insulation of components. Wafer-level alignment sintering is used to improve packaging efficiency. Visual alignment of the vibration beam assembly improves assembly accuracy, thereby improving the vibration resistance of the structure.

[0106] (3) The three tuning fork vibration beams 229 are integrated into one design with good process consistency. The reference vibration beam 222 is used to suppress the temperature drift of the pressure measuring vibration beam 221. The matching tuning fork vibration beam 229 is designed to improve the symmetry of the sensitive structure, thereby suppressing the mechanical common mode error. The reference vibration beam 222 leads out the electrode through the folding beam 230 with extremely low stiffness, realizing lead-free connection inside the sensitive structure.

[0107] (4) The design of the pressure-sensitive membrane 110 with a top-level flat membrane structure can better sense assembly stress and thermal stress, making the stress more consistent, thereby improving the temperature change and overload resistance of the pressure-sensitive membrane 110 and ensuring the zero-bias stability of the vibration beam.

[0108] 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) and a convex platform (112), wherein the convex platform (112) is arranged in the first concave cavity (111), and the first concave cavity (111) and the convex platform (112) form a stress isolation groove structure; A vibration beam layer (200), the vibration beam layer (200) comprising a vibration beam base (210) and a plurality of vibration beam structures (220), the vibration beam base (210) being connected to a side of the pressure-sensing layer (100) provided with the first concave cavity (111), the vibration beam structure (220) being connected to the vibration beam base (210), the vibration beam structure (220) comprising 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) being fixedly connected On the boss (112), the anchor region (226) of the reference vibration beam (222) is fixedly connected to the vibration beam base (210); the first excitation electrode (224) of the reference vibration beam (222) is led out by routing on 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); The base layer (300) is connected to the vibration beam layer (200), and the vibration beam layer (200) is arranged between the pressure-sensitive layer (100) and the base layer (300).

2. The pressure sensor sensitive structure according to claim 1, characterized in that: The vibration beam layer (200) comprises a folded beam (230), and the second excitation electrode (225) of the pressure measuring vibration beam (221) is electrically led out via the folded beam (230).

3. The pressure sensor sensitive structure according to claim 1, characterized in that: The number of the bosses (112) is set corresponding to the number of the anchoring areas (226) of the pressure measuring vibration beam (221); the number of the anchoring areas (226) of the pressure measuring vibration beam (221) is two, and the anchoring areas (226) of the two pressure measuring vibration beams (221) are arranged at intervals.

4. The pressure sensor sensitive structure according to claim 1, 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).

5. The pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The pressure-sensitive film (110) is a quartz crystal pressure-sensitive film (110), the pressure-measuring vibration beam (221) is a quartz crystal pressure-measuring vibration beam (221), the reference vibration beam (222) is a quartz crystal reference vibration beam (222), and the base layer (300) is a quartz crystal base layer (300).

6. The pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The anchor area (226) of the pressure measuring vibration beam (221) is fixedly connected to the boss (112) via an adhesive material, wherein the adhesive material is one of glass paste, metal solder, epoxy glue and gold-gold bonding material.

7. The pressure sensor sensitive structure according to any one of claims 1 to 4, characterized in that: The base layer (300) is provided with a second concave cavity (310), and the second concave cavity (310) opens toward the vibration beam layer (200).

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