MEMS resonant pressure sensor and manufacturing method thereof

Abstract

The invention relates to the technical field of pressure sensors. The invention specifically relates to an MEMS resonant pressure sensor and a manufacturing method thereof. The MEMS resonant pressure sensor provided by the invention comprises a substrate layer; the substrate layer comprises a sensitive film; the sensitive film is suitable for converting pressure applied by the sensor into stress; an intermediate layer; the middle layer comprises a harmonic oscillator structure; the harmonic oscillator structure is connected to the sensitive film through the anchor area and is suitable for converting stress converted by the sensitive film into resonant motion of the harmonic oscillator structure. The middle layer further comprises an excitation detection structure; and the excitation detection structure is arranged at the side part of the harmonic oscillator structure and is suitable for exciting the resonant motion of the harmonic oscillator structure, detecting the frequency of the resonant motion and calculating the pressure applied by the sensor through the output electric signal. The harmonic oscillator structure comprises a resonant beam and a fixed beam which is perpendicular to the resonant beam and is connected with the resonant beam. One end of the fixed beam is connected to the midpoint of the resonant beam. The MEMS resonant pressure sensor provided by the invention has relatively high sensitivity.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure sensors, and in particular to a MEMS resonant pressure sensor and a manufacturing method thereof. Background Art

[0002] MEMS silicon micromechanical resonant pressure sensor is an instrument that measures pressure by detecting the change in the natural frequency of the resonant beam. Compared with traditional sensors, resonant pressure sensors have the advantages of small size, light weight, easy integration, high measurement accuracy, and mass production. It has broad development prospects in the future.

[0003] Sensitivity is one of the key indicators of pressure sensors. High-sensitivity pressure sensors can detect smaller pressure changes, which is reflected in the resonant pressure sensor as a higher frequency change of the resonator under unit pressure. In order to make the resonant pressure sensor more sensitive, researchers usually reduce the diaphragm thickness of the sensitive membrane or increase the diaphragm area. However, this approach is inevitably accompanied by a reduction in the range, which limits its universality in various occasions.

[0004] Therefore, a solution is needed to improve the sensitivity of the pressure sensor without reducing the range of the pressure sensor. Summary of the invention

[0005] Therefore, the present invention provides a MEMS resonant pressure sensor and a method for manufacturing the same, so as to solve the problem that the pressure sensor inevitably has a reduced range when the sensitivity is improved.

[0006] In one aspect of the present invention, the present invention provides a MEMS resonant pressure sensor, comprising: a substrate layer; the substrate layer comprises a sensitive film; the sensitive film is suitable for converting the pressure applied to the sensor into stress; an intermediate layer; the intermediate layer comprises a resonator structure; the resonator structure is connected to the sensitive film through an anchor region, and is suitable for converting the stress converted by the sensitive film into its own resonant motion; the intermediate layer also comprises an excitation detection structure; the excitation detection structure is arranged on the side of the resonator structure, and is suitable for exciting the resonant motion of the resonator structure and detecting the frequency of its resonant motion and converting it into an electrical signal to calculate the pressure applied to the sensor. Wherein, the resonator structure comprises a resonant beam and a fixed beam perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam.

[0007] The MEMS resonant pressure sensor provided by the present invention has a resonant structure including a resonant beam and a fixed beam which is perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam. The resonant beam and the fixed beam arranged in this way constitute a T-shaped resonant beam, and the fixed beam is used to structurally constrain the first-order horizontal vibration mode of the resonant beam, and the process of spontaneously transforming the resonant beam from the second-order mode to the first-order mode is constrained to a constant first-order mode. Without increasing the working mode and changing the overall structural size, the stress-frequency response of the sensor is greatly improved, so that the resonant pressure sensor has a higher frequency change under unit pressure, and can detect smaller pressure changes, thereby achieving the purpose of improving the sensitivity of the resonant pressure sensor. In addition, the present application does not make any special restrictions on the area or thickness of the sensitive film, that is, the sensitive film does not have a change in area or thickness relative to the prior art, and only the resonator is structurally optimized, so it will not affect the range of the pressure sensor.

[0008] Furthermore, the anchor area includes a first anchor area at both ends of the resonant beam and a second anchor area at one end of the fixed beam away from the resonant beam; the first anchor area and the second anchor area are connected to the sensitive film through a sacrificial layer; the resonant beam and the fixed beam are suspended above the sensitive film, and are separated from the sensitive film by the height of the sacrificial layer.

[0009] The MEMS resonant pressure sensor provided by the present invention connects the resonant beam and the fixed beam to the sensitive film through the first anchor region and the second anchor region respectively, so that they can realize their respective resonant modes and transform the stress of the sensitive film.

[0010] Furthermore, the excitation detection structure includes an excitation unit and a detection unit arranged on the side of the resonant beam; the excitation unit and the detection unit are respectively led out to the periphery of the sensitive film through a signal transmission unit, and the signal transmission unit is provided with a lead-out contact on the surface of one end of the periphery of the sensitive film.

[0011] The MEMS resonant pressure sensor provided by the present invention leads out the excitation unit and the detection unit through the signal transmission unit and the lead-out contact to connect to the external circuit, and the resonator unit is excited and detected through the external circuit. And because the lead-out contact is located outside the sensitive film, it will not affect the stress conversion of pressure.

[0012] Furthermore, the substrate layer also includes: a substrate outer frame, which is arranged on the periphery of the sensitive film and connected to the sensitive film to form an integrated structure; the intermediate layer also includes: a middle layer outer frame, which is arranged on the periphery of the resonator structure and the excitation detection structure and is connected to the substrate outer frame through a sacrificial layer; the middle layer outer frame is spaced apart from the resonator structure and the excitation detection structure.

[0013] Furthermore, the MEMS resonant pressure sensor provided by the present invention also includes: a cover layer; the cover layer includes a cover, and a through hole penetrating the cover from the thickness direction is arranged at the corresponding lead-out contact of the cover, and the lead-out electrode is filled in the through hole; the lead-out electrode corresponds to the position of the lead-out contact; a contact electrode is arranged between the lead-out electrode and the lead-out contact, and the contact electrode is electrically contacted with the lead-out contact and the lead-out electrode respectively.

[0014] Furthermore, the MEMS resonant pressure sensor provided by the present invention also includes: a temperature compensation structure; the temperature compensation structure is arranged in the middle layer, and is spaced apart from the resonator structure and the excitation detection structure; the temperature compensation structure includes: a carrier, one end of the carrier is connected to the outer frame of the substrate through a sacrificial layer, and the rest of the carrier is suspended in the substrate layer, and is spaced apart from the substrate layer by the height of the sacrificial layer; a filling layer, the filling layer covers the surface of the carrier; resistors, the resistors are arranged on the surface of the filling layer; the resistors are led out to positions corresponding to the periphery of the sensitive film, the lead-out contacts connected to the resistors are different from the lead-out contacts connected to the detection unit and the excitation unit, and the lead-out contacts connected to the resistors are located on the filling layer to lead out the temperature signal.

[0015] The MEMS resonant pressure sensor provided by the present invention can, through the setting of the temperature compensation structure, reflect the ambient temperature during measurement through the resistance change of the resistor during pressure detection, and can provide the external circuit with the electrical signal change of the resistor through the lead-out contact, thereby providing a temperature compensation basis for the calculation of pressure.

[0016] Furthermore, the filling layer also covers the middle outer frame, and an adhesive layer is provided on the surface of the filling layer at a position corresponding to the middle outer frame, so as to be bonded to the cover plate at the position of the adhesive layer;

[0017] The MEMS resonant pressure sensor provided by the present invention realizes the flatness of the overall structure by setting the filling layer, so that the overall structure is stable.

[0018] In another aspect of the present invention, the present invention provides a method for manufacturing a MEMS resonant pressure sensor, comprising the following steps: forming a substrate layer; the substrate layer includes a sensitive film; the sensitive film is suitable for converting the pressure applied to the sensor into stress; forming an intermediate layer; the intermediate layer includes a resonator structure; the resonator structure is connected to the sensitive film through an anchor region, and is suitable for converting the stress converted by the sensitive film into its own resonant motion; the intermediate layer also includes an excitation detection structure; the excitation detection structure is arranged on the side of the resonator structure, and is suitable for exciting the resonant motion of the resonator structure and detecting the frequency of its resonant motion and converting it into an electrical signal to calculate the pressure applied to the sensor. Wherein, the resonator structure includes a resonant beam and a fixed beam perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam.

[0019] The manufacturing method of the MEMS resonant pressure sensor provided by the present invention can manufacture the pressure sensor provided by the present invention. The MEMS resonant pressure sensor provided by the present invention, the resonator structure includes a resonant beam and a fixed beam perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam. The resonant beam and the fixed beam arranged in this way constitute a T-shaped resonant beam, and the first-order horizontal vibration mode of the resonant beam is structurally constrained and eliminated by the fixed beam, and the second-order mode of the resonant beam is constrained to a constant first-order mode. Without increasing the working mode and changing the overall structural size, the stress-frequency response of the sensor is greatly improved, so that the resonant pressure sensor has a higher frequency change under unit pressure, and can detect smaller pressure changes, thereby achieving the purpose of improving the sensitivity of the resonant pressure sensor. In addition, the present application scheme does not make any special restrictions on the area or thickness of the sensitive film, that is, the sensitive film has no change in area or thickness relative to the prior art, and only the resonator is structurally optimized, so it will not affect the range of the pressure sensor.

[0020] Furthermore, the step of forming a substrate layer includes: providing an initial substrate, etching the initial substrate, forming a sensitive film and a substrate outer frame surrounding the sensitive film; the substrate outer frame is connected to the sensitive film into an integrated structure; the step of forming an intermediate layer includes: forming a sacrificial layer on one surface of the substrate layer; forming an initial intermediate layer on the surface of the sacrificial layer facing away from the substrate layer; etching the initial intermediate layer to form a resonator structure, an anchor area, an excitation detection structure and a middle layer outer frame; corroding and releasing part of the sacrificial layer through the gaps between the various structures of the intermediate layer, removing the silicon dioxide layer between the resonant beam and the fixed beam and the substrate layer, and leaving the resonant beam and the fixed beam suspended in the air.

[0021] Furthermore, the step of forming the intermediate layer also includes: in the step of etching the initial intermediate layer, a carrier separated from the resonator structure, the anchor area, the excitation detection structure and the middle layer outer frame is simultaneously formed; a filling layer is deposited on the surface of the carrier facing away from the substrate layer, and the filling layer covers the surface of the carrier; a resistor is deposited on the surface of the filling layer, and the resistor is led out to a position corresponding to the periphery of the sensitive film.

[0022] Furthermore, the manufacturing method of the MEMS resonant pressure sensor also includes: forming a plurality of lead-out contacts, the lead-out contacts are located at one end of the signal transmission unit corresponding to the periphery of the sensitive film. The lead-out contacts connected to the resistor are different from the lead-out contacts connected to the detection unit and the excitation unit. The lead-out contacts connected to the detection unit and the excitation unit are located on the surface of one end of the periphery of the sensitive film to lead out the resonant signal; the lead-out contacts connected to the resistor are located on the upper surface of the filling layer to lead out the temperature signal.

[0023] Furthermore, the manufacturing method of the MEMS resonant pressure sensor also includes: forming a cover layer; including: providing a cover; forming a through hole penetrating the cover from the thickness direction at the corresponding lead-out contact of the cover; filling metal in the through hole to form a lead-out electrode; the filling layer also covers the middle layer outer frame; forming an adhesive layer at the position of the filling layer corresponding to the middle layer outer frame; covering the cover on the filling layer, and fixedly connected to the filling layer at the corresponding middle layer outer frame through the adhesive layer; the lead-out electrode is contact-connected with the contact electrode accordingly.

[0024] The manufacturing method and structural process of the MEMS resonant pressure sensor provided by the present invention have good compatibility with the resonant accelerometer and the MEMS gyroscope structure, and are convenient for the integrated design of subsequent structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic cross-sectional structure diagram of a MEMS resonant pressure sensor according to an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the overall appearance of a MEMS resonant pressure sensor according to an embodiment of the present invention;

[0028] Figure 3 A schematic top view of an intermediate layer of a MEMS resonant pressure sensor according to an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the structure of a MEMS resonant pressure sensor showing a resonant subunit and an excitation detection unit according to an embodiment of the present invention;

[0030] Figure 5 A schematic diagram of a local structure of a MEMS resonant pressure sensor showing a lead-out contact point according to an embodiment of the present invention;

[0031] Figure 6 A schematic diagram of a partial structure of a temperature compensation unit of a MEMS resonant pressure sensor according to an embodiment of the present invention;

[0032] Figure 7 This is a schematic structural diagram of a MEMS resonant pressure sensor according to an embodiment of the present invention after a portion of the cover plate is removed;

[0033] Figure 8A partial schematic diagram of a MEMS resonant pressure sensor showing the connection state between a lead-out contact and a lead-out electrode according to an embodiment of the present invention;

[0034] Fig. 9 FIG. 1 is a schematic diagram comparing a resonator unit of a MEMS resonant pressure sensor according to an embodiment of the present invention and a traditional resonator unit. DETAILED DESCRIPTION

[0035] In order to solve the problem that the range of pressure sensors is inevitably reduced while the sensitivity is improved, the inventors of the present application have proposed a MEMS resonant pressure sensor and a manufacturing method thereof after careful research, so as to improve the sensitivity of the pressure sensor without reducing the range of the pressure sensor.

[0036] The present invention provides a MEMS resonant pressure sensor, comprising: a substrate layer; the substrate layer comprises a sensitive film; the sensitive film is suitable for converting the pressure applied to the sensor into stress; an intermediate layer; the intermediate layer comprises a resonator structure; the resonator structure is connected to the sensitive film through an anchor region, and is suitable for converting the stress converted by the sensitive film into its own resonant motion; the intermediate layer also comprises an excitation detection structure; the excitation detection structure is arranged on the side of the resonator structure, and is suitable for exciting the resonant motion of the resonator structure and detecting the frequency of its resonant motion, and calculating the pressure applied to the sensor through the output electrical signal. Wherein, the resonator structure comprises a resonant beam and a fixed beam perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam.

[0037] The present invention provides a method for manufacturing a MEMS resonant pressure sensor, comprising the following steps: forming a substrate layer; the substrate layer includes a sensitive film; the sensitive film is suitable for converting the pressure applied to the sensor into stress; forming an intermediate layer; the intermediate layer includes a resonator structure; the resonator structure is connected to the sensitive film through an anchor region, and is suitable for converting the stress converted by the sensitive film into its own resonant motion; the intermediate layer also includes an excitation detection structure; the excitation detection structure is arranged on the side of the resonator structure, and is suitable for exciting the resonant motion of the resonator structure and detecting the frequency of its resonant motion and converting it into an electrical signal to calculate the pressure applied to the sensor. Wherein, the resonator structure includes a resonant beam and a fixed beam perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam.

[0038] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0039] Example 1

[0040] refer to Figure 1-Figure 8 This embodiment provides a MEMS resonant pressure sensor, including:

[0041] The substrate layer comprises a sensitive film 12; the sensitive film 12 is suitable for converting the pressure applied to the sensor into stress;

[0042] The middle layer includes a resonator structure; the resonator structure is connected to the sensitive film 12 through the anchor region 10, and is suitable for converting the stress converted by the sensitive film 12 into its own resonant motion;

[0043] The middle layer also includes an excitation detection structure; the excitation detection structure is arranged on the side of the resonator structure, suitable for exciting the resonant motion of the resonator structure and detecting the frequency of its resonant motion and converting it into an electrical signal to calculate the pressure applied to the sensor.

[0044] The resonator structure includes a resonant beam 18 and a fixed beam 19 which is perpendicular to and connected to the resonant beam 18 ; one end of the fixed beam 19 is connected to the midpoint of the resonant beam 18 .

[0045] The MEMS resonant pressure sensor provided in this embodiment has a resonant substructure including a resonant beam 18 and a fixed beam 19 which is perpendicular to and connected to the resonant beam 18; one end of the fixed beam 19 is connected to the midpoint of the resonant beam 18. The resonant beam 18 and the fixed beam 19 thus arranged constitute a T-shaped resonant beam 9, and the fixed beam 19 is used to structurally constrain the first-order horizontal vibration mode of the resonant beam 18, and the second-order mode of the resonant beam 18 is constrained to the first-order mode. Without increasing the working mode and changing the overall structural size, the stress-frequency response of the sensor is greatly improved, so that the resonant pressure sensor has a higher frequency change under unit pressure, and can detect smaller pressure changes, thereby achieving the purpose of improving the sensitivity of the resonant pressure sensor.

[0046] Specifically, the resonant beam 18 and the fixed beam 19 form a T-shaped resonant beam 9. When the fixed beam 19 is not provided, the resonance of the resonant beam 18 is as follows: Fig. 9 As shown in , there are two states shown in the middle and right sides. The middle one is the first-order vibration mode, and the right side is the second-order vibration mode. For a naturally resonant oscillator, its first-order mode has a higher energy share and a lower energy level. When the oscillator is in a second-order excitation state, part of its second-order energy will flow to the first-order. Therefore, the system always tends to transform to the first-order mode, and the loss of energy will reduce the original quality factor. By introducing the fixed beam 19, the first-order mode of horizontal vibration is constrained and eliminated, and the second-order mode of the resonant beam is constrained to be constant. Fig. 9The mode on the left side of the middle, and at this time, since the resonant beam has only one resonant mode, this state is the first-order mode of the resonant substructure of this embodiment, which is the same as the second-order mode of the resonant beam 18 without the fixed beam 19. However, since there is only one first-order mode, there will be no conversion to the original first-order mode ( Fig. 9 The change tendency of the intermediate state) is constant to the first-order mode ( Fig. 9 The state on the left side of the middle), so that this first-order mode not only retains the original high-order mode ( Fig. 9 The state on the right side of the middle) has a high sensitivity characteristic, and a relatively stable mode is also obtained. Therefore, without increasing the working mode and changing the overall structural size, the stress-frequency response of the sensor can be greatly improved, so that the resonant pressure sensor has a higher frequency change under unit pressure, and then can detect smaller pressure changes, thereby achieving the purpose of improving the sensitivity of the resonant pressure sensor. In addition, the present application does not make any special restrictions on the area or thickness of the sensitive film, that is, the sensitive film does not change in area or thickness relative to the prior art, and only the structure of the resonator is optimized, so it will not affect the range of the pressure sensor.

[0047] Furthermore, in some embodiments of the present invention, the anchor region 10 includes a first anchor region at both ends of the resonant beam 18 and a second anchor region of the fixed beam 19 away from one end of the resonant beam 18; the first anchor region and the second anchor region are connected to the sensitive film 12 through the sacrificial layer 8; the resonant beam 18 and the fixed beam 19 are suspended above the sensitive film 12, and are separated from the sensitive film 12 by the height of the sacrificial layer 8.

[0048] The MEMS resonant pressure sensor provided in this embodiment connects the resonant beam 18 and the fixed beam 19 to the sensitive film 12 through the first anchor region and the second anchor region respectively, so that they can realize their respective resonant modes and transform the stress of the sensitive film 12 .

[0049] Furthermore, in some embodiments of the present invention, the excitation detection structure includes an excitation unit 16 and a detection unit 17 arranged on the side of the resonant beam 18; the excitation unit 16 and the detection unit 17 are respectively led out to the periphery of the sensitive film 12 through the signal transmission unit 7, and the signal transmission unit 7 is provided with a lead-out contact 20 and a contact electrode 3 located on the surface of the lead-out contact on one end of the periphery of the sensitive film 12.

[0050] As shown in the figure, on both sides of the fixed beam 19, different excitation units 16 are located on one side of the resonant beam 18, and different detection units 17 are located on the other side of the resonant beam 18. In some other embodiments, the positions of different excitation units 16 and different detection units 17 can be changed, not limited to being located on one side of the resonant beam, two or more excitation units 16 can be located on different sides of the resonant beam 18, and the same is true for the detection units 17. However, the excitation units 16 and the detection units 17 are always arranged relative to each other.

[0051] The MEMS resonant pressure sensor provided in this embodiment leads the excitation unit 16 and the detection unit 17 through the signal transmission unit 7 and the lead-out contact 20 to connect to the external circuit, and the resonator unit is excited and detected through the external circuit. And because the lead-out contact 20 is located outside the sensitive film 12, it will not affect the stress conversion of pressure.

[0052] Furthermore, in some embodiments of the present invention, the base layer further comprises:

[0053] The base outer frame 11 is arranged on the periphery of the sensitive film 12 and connected to the sensitive film 12 to form an integrated structure; the intermediate layer also includes: a middle layer outer frame 6, which is arranged on the periphery of the resonator structure and the excitation detection structure and connected to the base outer frame 11 through a sacrificial layer 8; the middle layer outer frame 6 is spaced apart from the resonator structure and the excitation detection structure.

[0054] Furthermore, in some embodiments of the present invention, the MEMS resonant pressure sensor further includes:

[0055] The cover plate layer comprises a cover plate 2, at the position of the cover plate 2 corresponding to the lead-out contact 20, a through hole penetrating the cover plate 2 in the thickness direction is provided, and the lead-out electrode 1 is filled in the through hole; the lead-out electrode 1 corresponds to the position of the lead-out contact 20; a contact electrode 3 is provided between the lead-out electrode 1 and the lead-out contact 20, and the contact electrode 3 is in electrical contact with the lead-out contact 20 and the lead-out electrode 1 respectively.

[0056] Further, in some embodiments of the present invention, the MEMS resonant pressure sensor also includes: a temperature compensation structure; the temperature compensation structure is arranged in the middle layer, and is spaced apart from the resonator structure and the excitation detection structure; the temperature compensation structure includes: a carrier 13, one end of the carrier 13 is connected to the base outer frame 11 through the sacrificial layer 8, and the rest of the carrier 13 is suspended in the base layer, and is spaced apart from the base layer by the height of the sacrificial layer 8; a filling layer 5, the filling layer 5 covers the surface of the carrier 13; a resistor 15, the resistor 15 is arranged on the surface of the filling layer 5; the resistor 15 is led out to a position corresponding to the periphery of the sensitive film 12, and the lead-out contact 20 connected to the resistor 15 is a different lead-out contact from the lead-out contact 20 connected to the detection unit 16 and the excitation unit 17. The lead-out contact connecting the detection unit and the excitation unit is located on the surface of one end of the periphery of the sensitive film to lead out the resonance signal; the lead-out contact connected to the resistor is located on the upper surface of the filling layer to lead out the temperature signal.

[0057] The MEMS resonant pressure sensor provided in this embodiment can, through the setting of the temperature compensation structure, reflect the ambient temperature during measurement through the resistance change of the resistor 15 during pressure detection, and can provide the external circuit with an electrical signal change of the resistor through the lead-out contact 20, thereby providing a temperature compensation basis for the calculation of pressure.

[0058] Furthermore, in some embodiments of the present invention, the filling layer 5 also covers the middle outer frame 6 , and an adhesive layer 4 is provided on the surface of the filling layer 5 at a position corresponding to the middle outer frame 6 so as to be bonded to the cover plate 2 at the position of the adhesive layer 4 .

[0059] The MEMS resonant pressure sensor provided in this embodiment realizes the flatness of the overall structure by disposing the filling layer 5, so that the overall structure is stable.

[0060] In addition, the MEMS resonant pressure sensor provided in this embodiment also has a spatial cavity 14, which accommodates the resonator structure, the excitation detection structure and the temperature compensation structure, and is surrounded by the base layer, the middle layer and the cover layer.

[0061] In the above structure, the material of the base layer is, for example, silicon, the material of the intermediate layer is, for example, silicon, the material of the sacrificial layer 8 is, for example, silicon dioxide, the material of the filling layer 5 is, for example, silicon nitride, the material of the resistor 15 is, for example, platinum, the material of the lead-out node 20 is, for example, platinum, the material of the contact electrode 3 is, for example, gold, the material of the cover plate 2 is, for example, silicon dioxide, and the material of the lead-out electrode 1 is, for example, copper.

[0062] Example 2

[0063] This embodiment provides a method for manufacturing a MEMS resonant pressure sensor, comprising the following steps: forming a substrate layer; the substrate layer includes a sensitive film 12; the sensitive film 12 is suitable for converting the pressure applied to the sensor into stress; forming an intermediate layer; the intermediate layer includes a resonator structure; the resonator structure is connected to the sensitive film 12 through an anchor region 10, and is suitable for converting the stress converted by the sensitive film 12 into its own resonant motion; the intermediate layer also includes an excitation detection structure; the excitation detection structure is arranged on the side of the resonator structure, and is suitable for exciting the resonant motion of the resonator structure and detecting the frequency of its resonant motion, and calculating the pressure applied to the sensor through the output electrical signal. Wherein, the resonator structure includes a resonant beam 18 and a fixed beam 19 that is perpendicular to and connected to the resonant beam 18; one end of the fixed beam 19 is connected to the midpoint of the resonant beam 18.

[0064] The manufacturing method of the MEMS resonant pressure sensor provided in this embodiment can manufacture the pressure sensor provided in this embodiment. The MEMS resonant pressure sensor provided in this embodiment, the resonator structure includes a resonant beam 18 and a fixed beam 19 which is perpendicular to and connected to the resonant beam 18; one end of the fixed beam 19 is connected to the midpoint of the resonant beam 18. The resonant beam 18 and the fixed beam 19 arranged in this way constitute a T-shaped resonant beam 9, and the fixed beam 19 is used to structurally constrain the first-order horizontal vibration mode of the resonant beam 18, and the process of spontaneously transforming the resonant beam 18 from the second-order mode to the first-order mode is constrained to a constant first-order mode. Without increasing the working mode and changing the overall structural size, the stress-frequency response of the sensor is greatly improved, so that the resonant pressure sensor has a higher frequency change under unit pressure, and can detect smaller pressure changes, thereby achieving the purpose of improving the sensitivity of the resonant pressure sensor. In addition, the present application scheme does not make any special restrictions on the area or thickness of the sensitive film, that is, the sensitive film has no change in area or thickness relative to the prior art, and only the resonator is structurally optimized, so it will not affect the range of the pressure sensor.

[0065] Furthermore, the step of forming the substrate layer includes: providing an initial substrate, etching the initial substrate, forming a sensitive film 12 and a substrate outer frame 11 surrounding the outer periphery of the sensitive film 12; the substrate outer frame 11 is connected to the sensitive film 12 to form an integral structure; the step of forming the intermediate layer includes: forming a sacrificial layer 8 on one side of the substrate layer; forming an initial intermediate layer on the side of the sacrificial layer 8 facing away from the substrate layer; etching the initial intermediate layer to form a resonator structure, an anchor region 10, an excitation detection structure and a middle layer outer frame 6; corroding and releasing part of the sacrificial layer 8 through the gaps between the various structures of the intermediate layer, removing the silicon dioxide layer between the resonant beam 18 and the fixed beam 19 and the substrate layer, and making the resonant beam 18 and the fixed beam 19 suspended. For the sacrificial layer under the larger area of ​​the carrier, auxiliary release is required by etching release holes on the front side.

[0066] Furthermore, the step of forming the intermediate layer also includes: in the step of etching the initial intermediate layer, a carrier 13 separated from the resonator structure, the anchor area 10, the excitation detection structure and the middle layer outer frame 6 is simultaneously formed; a filling layer 5 is deposited on the surface of the carrier 13 facing away from the substrate layer, and the filling layer 5 covers the surface of the carrier 13; a resistor is deposited on the surface of the filling layer 5, and the resistor is led out to a position corresponding to the periphery of the sensitive film 12.

[0067] Furthermore, the manufacturing method of the MEMS resonant pressure sensor also includes: forming a plurality of lead-out contacts 20, some of the lead-out contacts 20 are connected to the excitation detection structure through the signal transmission unit 7; some of the lead-out contacts 20 are connected to the resistor 15; and contact electrodes 3 are formed on the lead-out contacts 20.

[0068] Furthermore, the manufacturing method of the MEMS resonant pressure sensor also includes: forming a cover layer; including: providing a cover 2; forming a through hole penetrating the cover 2 in the thickness direction at the cover 2 corresponding to the lead-out contact 20; filling metal in the through hole to form a lead-out electrode 1; the filling layer 5 also covers the position of the lead-out contact 20 corresponding to the signal transmission unit 7 led outward by the excitation unit 16 and the detection unit 17, and the corresponding lead-out contact 20 is formed on the filling layer 5 at this position; the filling layer 5 also covers the middle layer outer frame 6; forming an adhesive layer 4 at the position of the filling layer 5 corresponding to the middle layer outer frame 6; the cover is placed on the filling layer 5, and fixedly connected to the filling layer 5 at the corresponding middle layer outer frame 6 through the adhesive layer 4; the lead-out electrode 1 is contact-connected with the contact electrode 3 accordingly.

[0069] The manufacturing method of the MEMS resonant pressure sensor provided in this embodiment is manufactured based on an SOI wafer, and the structural process has good compatibility with the resonant accelerometer and the MEMS gyroscope structure, which facilitates the integrated design of the subsequent structure.

[0070] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A MEMS resonant pressure sensor, characterized in that: include: Base layer; The base layer includes a sensitive film; the sensitive film is suitable for converting the pressure applied to the sensor into stress; Middle layer; The intermediate layer includes a resonator structure; The resonator structure is connected to the sensitive film through an anchor region, and is suitable for converting the stress converted by the sensitive film into its own resonant motion; The intermediate layer further comprises an excitation detection structure; the excitation detection structure is arranged at the side of the resonator structure, and is suitable for exciting the resonant motion of the resonator structure and detecting the frequency of the resonant motion, and calculating the pressure applied to the sensor through the output electrical signal; The resonator structure includes a resonant beam and a fixed beam which is perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam.

2. The MEMS resonant pressure sensor according to claim 1, characterized in that: The anchor region includes first anchor regions at both ends of the resonant beam and a second anchor region of the fixed beam away from one end of the resonant beam; The first anchor region and the second anchor region are connected to the sensitive film through a sacrificial layer; The resonant beam and the fixed beam are suspended above the sensitive film, and are spaced apart from the sensitive film by a height of the sacrificial layer.

3. The MEMS resonant pressure sensor according to claim 2, characterized in that: The excitation detection structure includes an excitation unit and a detection unit arranged at the side of the resonant beam; The excitation unit and the detection unit are respectively led out to the periphery of the sensitive film through a signal transmission unit, and the signal transmission unit is provided with a lead-out contact on a surface at one end of the periphery of the sensitive film.

4. The MEMS resonant pressure sensor according to claim 3, characterized in that: The substrate layer further comprises: a substrate outer frame, which is arranged at the periphery of the sensitive film and connected with the sensitive film to form an integral structure; The intermediate layer further comprises: a middle layer outer frame, which is arranged outside the resonator structure and the excitation detection structure and connected to the base outer frame through the sacrificial layer; the middle layer outer frame is spaced apart from the resonator structure and the excitation detection structure.

5. The MEMS resonant pressure sensor according to claim 4, characterized in that: Also includes: Covering layer; The cover plate layer includes a cover plate, wherein a through hole penetrating the cover plate in a thickness direction is provided at a position of the cover plate corresponding to the lead-out contact, and the lead-out electrode is filled in the through hole; the lead-out electrode corresponds to the position of the lead-out contact; A contact electrode is disposed between the lead-out electrode and the lead-out contact, and the contact electrode is in electrical contact with the lead-out contact and the lead-out electrode respectively.

6. The MEMS resonant pressure sensor according to claim 5, characterized in that: Also includes: Temperature compensation structure; The temperature compensation structure is arranged in the middle layer, and is spaced apart from the resonator structure and the excitation detection structure; The temperature compensation structure comprises: A carrier, one end of which is connected to the base outer frame through a sacrificial layer, and the rest of the carrier is suspended from the base layer and is spaced from the base layer by the height of the sacrificial layer; A filling layer, the filling layer covers the surface of the carrier; A resistor is arranged on the surface of the filling layer; the resistor is led out to a position corresponding to the periphery of the sensitive film, and a lead-out contact connected to the resistor is located on the filling layer to lead out the temperature signal.

7. The MEMS resonant pressure sensor according to claim 6, characterized in that: The filling layer also covers the middle outer frame, and an adhesive layer is provided on the surface of the filling layer at a position corresponding to the middle outer frame, so as to be bonded to the cover plate at the position of the adhesive layer.

8. A method for manufacturing a MEMS resonant pressure sensor, characterized in that: The following steps are involved: forming a matrix layer; The base layer includes a sensitive film; the sensitive film is suitable for converting the pressure applied to the sensor into stress; Forming an intermediate layer; The intermediate layer includes a resonator structure; The resonator structure is connected to the sensitive film through an anchor region, and is suitable for converting the stress converted by the sensitive film into its own resonant motion; The intermediate layer further comprises an excitation detection structure; the excitation detection structure is arranged at the side of the resonator structure, and is suitable for exciting the resonant motion of the resonator structure and detecting the frequency of the resonant motion, and calculating the pressure applied to the sensor through the output electrical signal; The resonator structure includes a resonant beam and a fixed beam which is perpendicular to and connected to the resonant beam; one end of the fixed beam is connected to the midpoint of the resonant beam.

9. The method for manufacturing a MEMS resonant pressure sensor according to claim 8, characterized in that: The step of forming the base layer comprises: Providing an initial substrate, etching the initial substrate to form the sensitive film and a substrate outer frame surrounding the sensitive film; the substrate outer frame and the sensitive film are connected to form an integral structure; The steps of forming the intermediate layer include: forming a sacrificial layer on one side surface of the base layer; forming an initial intermediate layer on a surface of the sacrificial layer facing away from the base layer; Etching the initial middle layer to form the resonator structure, the anchor region, the excitation detection structure and the middle layer outer frame; The sacrificial layer to be released is corroded through the gaps between the structures of the intermediate layer, and the silicon dioxide layer between the resonance beam, the fixed beam, and the carrier and the base layer is removed, so that the resonance beam, the fixed beam, and the carrier are suspended.

10. The method for manufacturing a MEMS resonant pressure sensor according to claim 9, characterized in that: The step of forming the intermediate layer further comprises: In the step of etching the initial intermediate layer, a carrier separated from the resonator structure, the anchor region, the excitation detection structure and the intermediate layer outer frame is simultaneously formed; Depositing a filling layer on the surface of the carrier facing away from the base layer, wherein the filling layer covers the surface of the carrier; A resistor is deposited on the surface of the filling layer, and the resistor is led out to a position corresponding to the periphery of the sensitive film.

11. The method for manufacturing a MEMS resonant pressure sensor according to claim 10, characterized in that: The excitation detection structure includes an excitation unit and a detection unit formed on the side of the resonant beam; The method for manufacturing the MEMS resonant pressure sensor further includes: A plurality of lead-out contacts are formed, some of which are connected to the excitation detection structure through the signal transmission unit; some of which are connected to the resistor; the lead-out contacts connecting the detection unit and the excitation unit are located on the outer surface of one end of the sensitive film to lead out the resonance signal; the lead-out contacts connected to the resistor are located on the upper surface of the filling layer to lead out the temperature signal; A contact electrode is formed on the lead-out contact.

12. The method for manufacturing a MEMS resonant pressure sensor according to claim 11, characterized in that: Also includes: Forming a cover layer; comprising: Provide cover plate; Forming a through hole penetrating the cover plate in the thickness direction at a position of the cover plate corresponding to the lead-out contact point; Filling metal in the through-hole to form a lead-out electrode; The filling layer also covers the middle outer frame; an adhesive layer is formed at a position of the filling layer corresponding to the middle outer frame; The cover plate is placed on the filling layer, and is fixedly connected to the filling layer via the adhesive layer at the corresponding position of the middle layer outer frame; the lead-out electrode is contact-connected with the contact electrode accordingly.

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