Silicon resonance pressure sensor

Abstract

The invention provides a silicon resonance pressure sensor. The silicon resonance pressure sensor comprises a pressure sensing layer, a resonance layer and a glass layer, one side, close to the resonance layer, of the pressure sensing layer is provided with a first pressure sensing groove, and two opposite sides in the first pressure sensing groove are respectively provided with a silicon island; the resonance layer comprises a cover plate, a mass block, an elastic piece, a resonance main beam, a resonance auxiliary beam, fixed comb teeth and movable comb teeth. The cover plate is arranged on the silicon island in a covering manner; the two ends of the mass block are connected with the two cover plates through elastic pieces respectively, a plurality of through holes are formed in the mass block, and the through holes form a honeycomb nest structure; the two ends of the resonance main beam are connected with the two cover plates respectively, the end, away from the resonance main beam, of the resonance auxiliary beam is connected with movable comb teeth, and the fixed comb teeth and the movable comb teeth are matched with each other to form an electrostatic comb tooth pair. One technical effect of the invention is that the temperature drift can be reduced, so that the accuracy of the measurement result of the silicon resonance pressure sensor is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of pressure sensors, and in particular relates to a silicon resonant pressure sensor. Background Art

[0002] The basic principle of the silicon resonant pressure sensor is based on the vibration principle of the resonator. The magnitude of the pressure to be measured is calculated by measuring the influence of the pressure to be measured on the vibration frequency of the resonator.

[0003] The current silicon resonant pressure sensor has temperature drift phenomenon. How to reduce the temperature drift of the silicon resonant pressure sensor has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a new technical solution for a silicon resonant pressure sensor.

[0005] According to one aspect of the present invention, a silicon resonant pressure sensor is provided, comprising a pressure-sensitive layer, a resonant layer and a glass layer; the pressure-sensitive layer, the resonant layer and the glass layer are bonded together in sequence from top to bottom;

[0006] A first pressure-sensing groove is disposed on one side of the pressure-sensing layer close to the resonance layer, and a silicon island is disposed on both opposite sides of the first pressure-sensing groove;

[0007] The resonance layer includes a cover plate, a mass block, an elastic member, a resonance main beam, a resonance sub-beam, fixed comb teeth and movable comb teeth; the cover plate corresponds to the position of the silicon island, and the cover plate is arranged on the silicon island; the mass block is located between the two silicon islands, and the two ends of the mass block are respectively connected to the two cover plates through the elastic member, and the mass block is provided with a plurality of through holes, and the plurality of through holes form a honeycomb structure; the two ends of the resonance main beam are respectively connected to the two cover plates, the middle part of the resonance main beam is connected to the resonance sub-beam, and the end of the resonance sub-beam away from the resonance main beam is provided with movable comb teeth, and the fixed comb teeth and the movable comb teeth cooperate with each other to form an electrostatic comb tooth pair;

[0008] A periodic driving signal is applied to the electrostatic comb teeth pair, so that the resonant secondary beam generates periodic vibration and drives the resonant main beam to generate periodic vibration;

[0009] When the pressure to be measured acts on the pressure-sensitive layer, the pressure-sensitive layer is deformed and the resonant main beam is deformed through the silicon island to change the resonant frequency of the resonant main beam. The pressure to be measured is measured by detecting the change in the resonant frequency of the resonant main beam.

[0010] Optionally, the silicon resonant pressure sensor further comprises a piezoresistive beam, wherein the piezoresistive beam is connected to the resonant sub-beam;

[0011] The resonant main beam, the resonant sub-beam, and the piezoresistive beam vibrate at the same frequency;

[0012] When the pressure to be measured acts on the pressure-sensitive layer, the change in the resonant frequency of the resonant main beam is measured by detecting the change in the frequency of the resistance of the piezoresistive beam.

[0013] Optionally, a plurality of concentric circular grooves are arranged on a side of the glass layer away from the resonance layer.

[0014] Optionally, the two piezoresistive beams are symmetrically arranged on opposite sides of the resonant sub-beam.

[0015] Optionally, the two cover plates are connected via the two resonant main beams; and the mass block is located between the two resonant main beams.

[0016] Optionally, each of the resonant main beams is connected to a resonant sub-beam, each of the resonant sub-beams corresponds to an electrostatic comb tooth pair, and two of the electrostatic comb tooth pairs are respectively located on opposite sides of the mass block.

[0017] Optionally, a second pressure-sensitive groove is provided on a side of the pressure-sensitive layer away from the resonance layer, and the second pressure-sensitive groove corresponds to a position of the first pressure-sensitive groove.

[0018] Optionally, the silicon resonant pressure sensor further comprises a connecting beam, and the resonant main beam is connected to the resonant sub-beam via the connecting beam; wherein a plurality of triangular holes are provided on the connecting beam.

[0019] Optionally, a glass groove is provided in the middle of one side of the glass layer close to the resonance layer, and a getter layer is provided on the bottom of the glass groove.

[0020] Optionally, the silicon resonant pressure sensor further includes a first pad, a second pad and a third pad;

[0021] The first pad is connected to the fixed comb teeth, the second pad is connected to the input end of the piezoresistive beam, and the third pad is connected to the output end of the piezoresistive beam.

[0022] A technical effect of the present invention is:

[0023] In the embodiment of the present application, the silicon resonant pressure sensor is provided with a honeycomb structure in the key heat transfer area of ​​the resonant layer, and the honeycomb structure as a heat dissipation structure can effectively reduce temperature drift. Furthermore, a plurality of triangular holes are provided on the connecting beam, and the plurality of triangular holes can dissipate heat, thereby helping to further reduce temperature drift. Therefore, the silicon resonant pressure sensor can reduce temperature drift, thereby ensuring the accuracy of the measurement results of the silicon resonant pressure sensor.

[0024] In addition, the honeycomb structure on the mass block can not only reduce the impact of temperature on the thermal stress of the resonant main beam, but also play a role in adjusting the weight of the mass block, thereby achieving the adjustment of the stiffness of the resonant main beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the main structure of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of an exploded structure of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0027] Figure 3 This is a schematic structural diagram of a second pressure-sensing groove of a pressure-sensing layer of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0028] Figure 4 This is a schematic structural diagram of a first pressure-sensing groove of a pressure-sensing layer of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0029] Figure 5 This is a schematic structural diagram of a resonant layer of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0030] Figure 6 A schematic diagram of the structure of an electrostatic comb pair of a resonant layer of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0031] Figure 7 It is an enlarged schematic diagram of an electrostatic comb tooth pair of a resonant layer of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0032] Figure 8 This is a schematic structural diagram of a glass layer of a silicon resonant pressure sensor according to an embodiment of the present invention;

[0033] Fig. 9 The figure is a cross-sectional schematic diagram of a silicon resonant pressure sensor according to an embodiment of the present invention.

[0034] In the figure: 1, pressure-sensitive layer; 11, first pressure-sensitive groove; 12, second pressure-sensitive groove; 13, silicon island; 2, resonance layer; 21, cover plate; 22, mass block; 221, honeycomb structure;

[0035] 23. Elastic part; 24. Resonant main beam; 25. Resonant sub-beam; 26. Fixed comb teeth; 27. Movable comb teeth; 28. Piezoresistive beam; 29. ​​Connecting beam; 291. Triangular hole; 3. Glass layer; 31. Concentric grooves; 32. Glass grooves; 33. Getter layer; 41. First pad; 42. Second pad; 43. Third pad. DETAILED DESCRIPTION

[0036] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0037] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0038] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0039] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0040] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0041] According to one aspect of the present invention, see Figures 1 to 9 , a silicon resonant pressure sensor is provided, comprising a pressure-sensitive layer 1, a resonant layer 2 and a glass layer 3; the pressure-sensitive layer 1, the resonant layer 2 and the glass layer 3 are bonded together in sequence from top to bottom;

[0042] A first pressure-sensing groove 11 is disposed on one side of the pressure-sensing layer 1 close to the resonance layer 2, and a silicon island 13 is disposed on both opposite sides of the first pressure-sensing groove 11;

[0043] The resonant layer 2 includes a cover plate 21, a mass block 22, an elastic member 23, a resonant main beam 24, a resonant sub-beam 25, fixed comb teeth 26 and movable comb teeth 27; the cover plate 21 corresponds to the position of the silicon island 13, and the cover plate 21 is covered on the silicon island 13; the mass block 22 is located between the two silicon islands 13, and the two ends of the mass block 22 are respectively connected to the two cover plates 21 through the elastic member 23, and the mass block 22 is provided with a plurality of through holes, and the plurality of through holes form a honeycomb structure 221; the two ends of the resonant main beam 24 are respectively connected to the two cover plates 21, the middle part of the resonant main beam 24 is connected to the resonant sub-beam 25, and the end of the resonant sub-beam 25 away from the resonant main beam 24 is provided with movable comb teeth 27, and the fixed comb teeth 26 and the movable comb teeth 27 cooperate with each other to form an electrostatic comb tooth pair;

[0044] A periodic driving signal is applied to the electrostatic comb teeth pair, so that the resonant sub-beam 25 generates periodic vibration and drives the resonant main beam 24 to generate periodic vibration;

[0045] When the pressure to be measured acts on the pressure-sensitive layer 1, the pressure-sensitive layer 1 is deformed and the resonant main beam 24 is deformed through the silicon island 13 to change the resonant frequency of the resonant main beam 24. The pressure to be measured is measured by detecting the change in the resonant frequency of the resonant main beam 24.

[0046] In the embodiment of the present application, the silicon resonant pressure sensor is provided with a honeycomb structure 221 in the key heat transfer area of ​​the resonant layer 2. The honeycomb structure 221 as a heat dissipation structure can effectively reduce temperature drift. Furthermore, a plurality of triangular holes 291 are provided on the connecting beam 29, and the plurality of triangular holes 291 can dissipate heat, thereby helping to further reduce temperature drift. Therefore, the silicon resonant pressure sensor can reduce temperature drift, thereby ensuring the accuracy of the measurement results of the silicon resonant pressure sensor.

[0047] In addition, the honeycomb structure 221 on the mass block 22 can not only reduce the influence of temperature on the thermal stress of the resonant main beam 24 , but also play a role in adjusting the weight of the mass block 22 , thereby achieving the adjustment of the stiffness of the resonant main beam 24 .

[0048] It should be noted that the working principle of the silicon resonant pressure sensor is as follows:

[0049] 1. Pressure sensing principle: The second pressure sensing groove 12 of the pressure sensing layer 1 is used to sense the external load (i.e., the pressure to be measured). The external load causes the pressure film of the resonance layer 2 to deform, thereby causing the silicon island 13 in the first pressure sensing groove 11 to deform, which helps to accurately measure the pressure.

[0050] Furthermore, the deformation of the silicon island 13 caused by the external load is transmitted to the resonant main beam 24 through the cover plate 21, thereby causing the resonant main beam 24 to bend and deform, and causing its stiffness to change, which occasionally causes its resonant frequency to change. By detecting the frequency change of the resonant main beam 24, the measurement of the external pressure load can be achieved.

[0051] 2. Driving principle: Since the resonant main beam 24 does not vibrate spontaneously, an external driving source is often required to make the resonant main beam 24 vibrate. The electrostatic driving method adopted in this application is that the fixed comb teeth 26 and the movable comb teeth 27 cooperate with each other to form an electrostatic comb tooth pair. By loading a periodic driving signal on the electrostatic comb tooth pair, the resonant sub-beam 25 drives the main beam 24 to produce periodic vibrations under the action of electrostatic force, and the vibration frequency will change with the change of the external load.

[0052] 3. Resonance frequency detection principle: The resonant frequency signal of the present application is indirectly measured through the piezoresistive beam 28 connected to the resonant structure, that is, the resonant sub-beam 25 drives the piezoresistive beam 28 to vibrate at the same frequency, and occasionally the measured resistance of the piezoresistive beam 28 will also change periodically at the same vibration frequency. By detecting the changing frequency of the resistance of the piezoresistive beam 28, the vibration frequency of the resonator (that is, the resonant main beam 24 and the resonant sub-beam 25) can be measured.

[0053] Optionally, the silicon resonant pressure sensor further includes a piezoresistive beam 28, wherein the piezoresistive beam 28 is connected to the resonant sub-beam 25;

[0054] The resonant main beam 24, the resonant sub-beam 25, and the piezoresistive beam 28 vibrate at the same frequency;

[0055] When the pressure to be measured acts on the pressure-sensitive layer 1 , the change in the resonant frequency of the resonant main beam 24 is measured by detecting the change in the resistance of the piezoresistive beam 28 .

[0056] In the above embodiment, the piezoresistive beam 28 helps to quickly and accurately measure the change in the resonant frequency of the resonant main beam 24, thereby helping to measure the external load.

[0057] Optionally, a side of the glass layer 3 away from the resonance layer 2 is provided with a plurality of concentric circular grooves 31. The plurality of concentric circular grooves 31 can significantly reduce the influence of packaging stress on the resonance structure of the silicon resonant pressure sensor.

[0058] Optionally, the two piezoresistive beams 28 are symmetrically arranged on opposite sides of the resonant sub-beam 25. The two piezoresistive beams 28 are symmetrically arranged, which makes the silicon resonant pressure sensor have better stability, and the redundant design makes the silicon resonant pressure sensor have a spare resonant frequency detection channel.

[0059] Optionally, the two cover plates 21 are connected by the two resonant main beams 24, and the mass block 22 is located between the two resonant main beams 24. This helps to ensure the stability of the vibration of the resonant main beam 24. In addition, while maintaining stability, the sensitivity can be increased, that is, the pressure to be measured is transmitted to the pressure-sensitive layer 1, and the mass blocks 22 symmetrically arranged on the pressure-sensitive layer 1 are deformed and squeeze the main beam 24, so that the resonant frequency of the silicon resonant pressure sensor is more sensitive to changes in external pressure.

[0060] Optionally, each of the resonant main beams 24 is connected to a resonant sub-beam 25, each of the resonant sub-beams 25 corresponds to an electrostatic comb tooth pair, and the two electrostatic comb tooth pairs are respectively located on opposite sides of the mass block 22. That is, the resonant layer symmetrically arranges two groups of resonators (i.e., electrostatic comb tooth pairs) on both sides of the mass block (which has a honeycomb structure), which can improve the structural stability of the silicon resonant pressure sensor on the one hand; on the other hand, the two groups of resonators vibrate on the same side, which can increase the stress of squeezing or stretching on the left and right sides of the piezoresistive beam, thereby causing the size deformation of the piezoresistive beam to be more obvious, which is convenient for the subsequent measurement of the resonant frequency.

[0061] Optionally, a second pressure-sensitive groove 12 is provided on a side of the pressure-sensitive layer 1 away from the resonance layer 2 , and the second pressure-sensitive groove 12 corresponds to the position of the first pressure-sensitive groove 11 .

[0062] In the above embodiment, the second pressure-sensing groove 12 of the pressure-sensing layer 1 is used to sense the external load (i.e., the pressure to be measured). The external load causes the pressure film of the resonance layer 2 to deform, thereby causing the silicon island 13 in the first pressure-sensing groove 11 to deform, thereby facilitating accurate pressure measurement.

[0063] Furthermore, the deformation of the silicon island 13 caused by the external load is transmitted to the resonant main beam 24 through the cover plate 21, thereby causing the resonant main beam 24 to bend and deform, and causing its stiffness to change, which occasionally causes its resonant frequency to change. By detecting the frequency change of the resonant main beam 24, the measurement of the external pressure load can be achieved.

[0064] Exemplarily, the silicon island 13 is connected to the cover plate 21 on the resonance layer 2 by silicon-silicon bonding.

[0065] Optionally, the silicon resonant pressure sensor further includes a connecting beam 29 , through which the resonant main beam 24 is connected to the resonant sub-beam 25 ; wherein a plurality of triangular holes 291 are provided on the connecting beam 29 .

[0066] Alternatively, see Figure 8 and Fig. 9 A glass groove 32 is provided in the middle of one side of the glass layer 3 close to the resonance layer 2, and a getter layer 33 is provided on the bottom of the glass groove 32. This helps to ensure the vacuum degree of the vibration space and improve the measurement accuracy of the silicon resonant pressure sensor.

[0067] Optionally, the silicon resonant pressure sensor further includes a first pad 41, a second pad 42 and a third pad 43;

[0068] The first pad 41 is connected to the fixed comb teeth 26 , the second pad 42 is connected to the input end of the piezoresistive beam 28 , and the third pad 43 is connected to the output end of the piezoresistive beam 28 .

[0069] In the above-mentioned implementation, the electrical connection of the various components of the silicon resonant pressure sensor can be achieved through the various pads, and the connection relationship is relatively simple.

[0070] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A silicon resonant pressure sensor, characterized in that: It comprises a pressure-sensitive layer, a resonance layer and a glass layer; the pressure-sensitive layer, the resonance layer and the glass layer are bonded together in sequence from top to bottom; A first pressure-sensing groove is disposed on one side of the pressure-sensing layer close to the resonance layer, and a silicon island is disposed on both opposite sides of the first pressure-sensing groove; The resonance layer includes a cover plate, a mass block, an elastic member, a resonance main beam, a resonance sub-beam, fixed comb teeth and movable comb teeth; the cover plate corresponds to the position of the silicon island, and the cover plate is arranged on the silicon island; the mass block is located between the two silicon islands, and the two ends of the mass block are respectively connected to the two cover plates through the elastic member, and the mass block is provided with a plurality of through holes, and the plurality of through holes form a honeycomb structure; the two ends of the resonance main beam are respectively connected to the two cover plates, the middle part of the resonance main beam is connected to the resonance sub-beam, and the end of the resonance sub-beam away from the resonance main beam is provided with movable comb teeth, and the fixed comb teeth and the movable comb teeth cooperate with each other to form an electrostatic comb tooth pair; A periodic driving signal is applied to the electrostatic comb teeth pair, so that the resonant secondary beam generates periodic vibration and drives the resonant main beam to generate periodic vibration; When the pressure to be measured acts on the pressure-sensitive layer, the pressure-sensitive layer is deformed and the resonant main beam is deformed through the silicon island to change the resonant frequency of the resonant main beam. The pressure to be measured is measured by detecting the change in the resonant frequency of the resonant main beam.

2. The silicon resonant pressure sensor according to claim 1, characterized in that: It also includes a piezoresistive beam, wherein the piezoresistive beam is connected to the resonant sub-beam; The resonant main beam, the resonant sub-beam, and the piezoresistive beam vibrate at the same frequency; When the pressure to be measured acts on the pressure-sensitive layer, the change in the resonant frequency of the resonant main beam is measured by detecting the change in the frequency of the resistance of the piezoresistive beam.

3. The silicon resonant pressure sensor according to claim 1, characterized in that: A plurality of concentric circular grooves are arranged on a side of the glass layer away from the resonance layer.

4. The silicon resonant pressure sensor according to claim 2, characterized in that: The two piezoresistive beams are symmetrically arranged on opposite sides of the resonant sub-beam.

5. The silicon resonant pressure sensor according to claim 1, characterized in that: The two cover plates are connected via the two resonant main beams; and the mass block is located between the two resonant main beams.

6. The silicon resonant pressure sensor according to claim 5, characterized in that: Each of the resonant main beams is connected to a resonant sub-beam, each of the resonant sub-beams corresponds to an electrostatic comb tooth pair, and two electrostatic comb tooth pairs are respectively located on opposite sides of the mass block.

7. The silicon resonant pressure sensor according to claim 1, characterized in that: A second pressure-sensitive groove is disposed on a side of the pressure-sensitive layer away from the resonance layer, and the second pressure-sensitive groove corresponds to the position of the first pressure-sensitive groove.

8. The silicon resonant pressure sensor according to claim 1, characterized in that: It also includes a connecting beam, and the resonant main beam is connected to the resonant sub-beam through the connecting beam.

9. The silicon resonant pressure sensor according to claim 1, characterized in that: A glass groove is arranged in the middle of one side of the glass layer close to the resonance layer, and a getter layer is arranged on the bottom of the glass groove.

10. The silicon resonant pressure sensor according to claim 2, characterized in that: Also includes a first pad, a second pad and a third pad; The first pad is connected to the fixed comb teeth, the second pad is connected to the input end of the piezoresistive beam, and the third pad is connected to the output end of the piezoresistive beam.

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