A method for fabricating a pressure sensor and the pressure sensor itself.

Abstract

This invention relates to the field of sensor technology, and more particularly to a method for fabricating a pressure sensor and the pressure sensor itself. The method for fabricating the pressure sensor includes the following steps: S1, fabricating a first groove on the lower surface of an upper layer and pre-reserving a boss within the first groove; S2, fabricating a resonator structure inside an intermediate layer; S3, aligning and bonding the upper surface of the intermediate layer with the lower surface of the upper layer, and bonding the free end of the resonator structure to the boss of the upper layer; S4, fabricating a second groove on the upper surface of a lower layer; S5, under vacuum conditions, aligning and bonding the upper surface of the lower layer and the lower surface of the intermediate layer to form a sealed cavity, with the bonding portion between the lower layer and the intermediate layer insulated; S6, fabricating a pressure-sensitive film on the upper surface of the upper layer; S7, fabricating electrodes on the upper layer, intermediate layer, and lower layer respectively. This fabrication method can solve the problems of vacuum packaging and wire interconnection, improve packaging reliability, enhance product performance, and reduce process costs.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a method for manufacturing a pressure sensor and a pressure sensor itself. Background Technology

[0002] Pressure sensors are becoming increasingly miniaturized, posing a growing challenge to pressure sensor packaging technology. Silicon resonant pressure sensors are among the most accurate MEMS pressure sensors, but also the most complex in terms of manufacturing process. A key challenge is achieving vacuum packaging of the resonator. Typically, anodic bonding and silicon-to-silicon bonding are the two bonding methods with the lowest stress, and these two vacuum packaging methods are currently the primary methods used in high-precision products. A crucial issue in the vacuum packaging process is resolving the conflict between vacuum packaging and wire interconnection.

[0003] Existing pressure sensors without lead wires or through holes require an additional reference voltage between the pressure-sensitive diaphragm and the resonator, in addition to the driving voltage that drives the resonator to move periodically. When the pressure-sensitive diaphragm is subjected to the pressure to be measured, the electrostatic force and capacitance between the pressure-sensitive diaphragm and the resonator change, which in turn causes the resonator's resonant frequency to change. The magnitude of the pressure to be measured is calculated based on the change in the resonant frequency. Therefore, the measured pressure includes the error factor of the reference voltage itself, thereby reducing the measurement accuracy of the pressure to be measured.

[0004] Therefore, there is an urgent need for a fabrication method for a vacuum-encapsulated pressure sensor without lead-through holes to solve the above problems. Summary of the Invention

[0005] One objective of this invention is to provide a method for processing a pressure sensor that can solve the problems of vacuum packaging and lead interconnection, improve packaging reliability, enhance product performance, and reduce process costs.

[0006] Another object of the present invention is to provide a pressure sensor that can be manufactured using the above-described pressure sensor processing method, which has higher packaging reliability, better product performance, and lower cost.

[0007] To achieve the above objectives, the following technical solution is provided:

[0008] In a first aspect, a method for fabricating a pressure sensor is provided. The pressure sensor includes an upper layer, an intermediate layer, and a lower layer, wherein the upper layer, the intermediate layer, and the lower layer are all semiconductors. The method for fabricating the pressure sensor includes the following steps:

[0009] S1. A first groove is made on the lower surface of the upper layer and a boss is reserved in the first groove;

[0010] S2. Fabricate a resonator structure inside the intermediate layer;

[0011] S3. Align and bond the upper surface of the intermediate layer with the lower surface of the upper layer, bond the free end of the resonator structure with the boss of the upper layer, and insulate the bonding portion between the intermediate layer and the upper layer.

[0012] S4. A second groove is made on the upper surface of the lower layer;

[0013] S5. Under vacuum conditions, the upper surface of the lower layer and the lower surface of the middle layer are aligned and bonded to form a sealed cavity, and the bonding portion between the lower layer and the middle layer is insulated and connected.

[0014] S6. A pressure-sensitive membrane is formed on the upper surface of the upper layer;

[0015] S7. Fabricate an upper electrode on the upper layer; fabricate an intermediate electrode on the middle layer; and fabricate a lower electrode on the lower layer.

[0016] As an optional embodiment of the processing method for the pressure sensor, the lower surface of the upper layer is oxidized before step S1; or

[0017] After step S1 and before step S3, the lower surface of the upper layer is subjected to an oxidation treatment; or

[0018] In step S3, the bonding sites between the intermediate layer and the upper layer are subjected to oxidation treatment.

[0019] As an optional embodiment of the processing method for the pressure sensor, the upper surface of the lower layer is subjected to an oxidation treatment after step S3 and before step S4; or

[0020] After step S4 and before step S5, the upper surface of the lower layer is subjected to an oxidation treatment; or

[0021] In step S5, the bonding sites between the intermediate layer and the lower layer are subjected to oxidation treatment.

[0022] As an optional embodiment of the processing method for the pressure sensor, the outer contours of the upper layer, the middle layer, and the lower layer are the same. Before step S7, the method further includes: cutting off a portion of the upper layer to expose a portion of the upper surface of the middle layer, and cutting off a portion of the middle layer to expose a portion of the upper surface of the lower layer.

[0023] As an optional embodiment of the processing method for the pressure sensor, in step S7, the upper electrode is fabricated on the upper surface of the upper layer; the intermediate electrode is fabricated on the upper surface of the middle layer; and the lower electrode is fabricated on the upper surface of the lower layer.

[0024] As an optional embodiment of the processing method for the pressure sensor, the outer contour formed by the groove sidewall of the second groove is the same as the outer contour formed by the groove sidewall of the first groove.

[0025] As an optional embodiment of the processing method for the pressure sensor, in step S5, a gasket is inserted between the intermediate layer and the lower layer, and then the intermediate layer and the lower layer are sent into the vacuum chamber of the bonding machine. The gasket is removed, and the intermediate layer and the lower layer are aligned and bonded together by applying pressure and heating to form the sealing cavity.

[0026] As an alternative to the processing method of the pressure sensor, in step S7, an aluminum metal thin film used as an electrode is formed using electron beam evaporation deposition technology.

[0027] In a second aspect, a pressure sensor is provided, the pressure sensor comprising an upper layer, a middle layer and a lower layer, wherein the upper layer, the middle layer and the lower layer are all semiconductors;

[0028] A first groove is formed on the lower surface of the upper layer, and a boss is protruding in the first groove;

[0029] The intermediate layer includes a frame-shaped portion and a cantilever portion. One end of the cantilever portion is connected to the interior of the frame-shaped portion to form a resonator structure. The upper surface of the frame-shaped portion is insulated and bonded to the lower surface of the upper layer, and the free end of the cantilever portion is insulated and bonded to the boss.

[0030] A second groove is formed on the upper surface of the lower layer, and the lower surface of the frame-shaped part is insulated and bonded to the upper surface of the lower layer to form a sealed cavity;

[0031] An upper electrode is provided on the upper layer; an intermediate electrode is provided on the middle layer; and a lower electrode is provided on the lower layer.

[0032] As an alternative to the aforementioned pressure sensor, the lower surface of the boss and the lower surface of the upper layer are located on the same horizontal plane.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The pressure sensor manufacturing method provided by this invention includes the following steps: S1, fabricating a first groove on the lower surface of an upper layer and reserving a boss within the first groove; S2, fabricating a resonator structure inside an intermediate layer; S3, aligning and bonding the upper surface of the intermediate layer with the lower surface of the upper layer, bonding the free end of the resonator structure to the boss of the upper layer, and insulating the bonding portion between the intermediate layer and the upper layer; S4, fabricating a second groove on the upper surface of the lower layer; S5, under vacuum conditions, aligning and bonding the upper surface of the lower layer and the lower surface of the intermediate layer to form a sealed cavity, and insulating the bonding portion between the lower layer and the intermediate layer; S6, fabricating a pressure-sensitive membrane on the upper surface of the upper layer; S7, fabricating an upper electrode on the upper layer; fabricating an intermediate electrode on the intermediate layer; and fabricating a lower electrode on the lower layer. This manufacturing method can solve the problems of vacuum packaging and wire interconnection, improve packaging reliability, enhance product performance, and reduce process costs.

[0035] The pressure sensor provided by this invention can be manufactured using the aforementioned pressure sensor processing method. This pressure sensor has higher packaging reliability, better product performance, and lower cost. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0037] Figure 1 This is an exploded view of a pressure sensor provided in an embodiment of the present invention;

[0038] Figure 2 This is a side sectional view of a pressure sensor provided in an embodiment of the present invention.

[0039] Figure label:

[0040] 100. Oxide layer;

[0041] 1. Upper layer; 11. First groove; 12. Boss; 13. Third groove;

[0042] 2. Intermediate layer; 21. Frame section; 22. Cantilever section;

[0043] 3. Lower layer; 31. Second groove;

[0044] 4. Upper electrode;

[0045] 5. Intermediate electrode;

[0046] 6. Lower electrode. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0049] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0050] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0051] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0052] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0053] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0054] like Figures 1-2 As shown, this embodiment provides a pressure sensor, which includes an upper layer 1, a middle layer 2, and a lower layer 3, all of which are semiconductors.

[0055] Optionally, a pressure-sensitive membrane is formed on the upper surface of the upper layer 1, and a first groove 11 is formed on the lower surface of the upper layer 1, with a boss 12 protruding inside the first groove 11; the middle layer 2 includes a frame-shaped portion 21 and a cantilever portion 22, one end of which is connected to the interior of the frame-shaped portion 21 to form a resonator structure; the upper surface of the frame-shaped portion 21 is insulated and bonded to the lower surface of the upper layer 1, and the free end of the cantilever portion 22 is insulated and bonded to the boss 12; a second groove 31 is formed on the upper surface of the lower layer 3, and the lower surface of the frame-shaped portion 21 is insulated and bonded to the upper surface of the lower layer 3 to form a sealed cavity; an upper electrode 4 is provided on the upper layer 1; an intermediate electrode 5 is provided on the middle layer 2; and a lower electrode 6 is provided on the lower layer 3.

[0056] This pressure sensor is made of semiconductors, avoiding the differences in expansion coefficients between heterogeneous materials and significantly improving its temperature characteristics. Furthermore, using semiconductors as the conductive material allows for direct molding of electrode structures onto each layer of the pressure sensor, achieving an integrated design of structure and electrodes. This eliminates the need for complex processes such as opening holes and metal filling, enabling a reliable and simple manufacturing process. In terms of chip size, the elimination of large-area sealed bezels allows for chip miniaturization.

[0057] The pressure detection principle of the pressure sensor provided in this embodiment is as follows: a cantilever resonator (the resonator structure formed by the cantilever portion 22 is cantilever-shaped) and the first groove 11 of the upper layer 1 constitute a driving capacitor, and the cantilever resonator (the resonator structure formed by the cantilever portion 22 is cantilever-shaped) and the lower layer 3 constitute a detection capacitor. By applying a periodic signal to the upper electrode 4, the cantilever resonator structure moves periodically, thereby changing the distance between it and the bottom surface of the second groove 31 on the lower layer 3, thus changing the detection capacitor. By detecting the change in the detection capacitor, the vibration frequency of the resonator structure is picked up. When pressure is applied to the pressure-sensitive membrane of the pressure sensor, it deforms, thereby causing a change in the stiffness of the cantilever resonator structure, which in turn causes a change in its frequency. The magnitude of the pressure is characterized by the change in the frequency signal of the detection electrode.

[0058] By connecting the pressure-sensitive membrane and the resonator structure, the pressure to be measured is directly transmitted to the resonator structure through physical contact. The vibration frequency of the resonator structure changes as a result, which is used to measure the pressure to be measured without the need to introduce a reference voltage, thus improving the accuracy of pressure measurement.

[0059] Preferably, a third groove 13 is formed on the upper surface of the upper layer 1, and the third groove 13 can serve as the base for forming the pressure-sensitive membrane.

[0060] Preferably, the lower surface of the boss 12 is on the same horizontal plane as the lower surface of the upper layer 1, so that the cantilever 22 is in a horizontal state when it is not subjected to a force.

[0061] Optionally, the upper layer 1, the middle layer 2, and the lower layer 3 are all silicon wafers.

[0062] Simulation calculations were performed on the pressure sensor provided in this embodiment. The resonator structure frequency has a linear relationship with the applied pressure, and its sensitivity is 15.8 Hz / kPa.

[0063] This embodiment provides a method for manufacturing a pressure sensor, which includes the following steps:

[0064] S1. A first groove 11 is made on the lower surface of the upper layer 1 and a boss 12 is reserved in the first groove 11;

[0065] S2. Fabricate a resonator structure inside the intermediate layer 2;

[0066] S3. Align and bond the upper surface of the intermediate layer 2 with the lower surface of the upper layer 1, bond the free end of the resonator structure with the boss 12 of the upper layer 1, and insulate the bonding area between the intermediate layer 2 and the upper layer 1.

[0067] S4. Create a second groove 31 on the upper surface of the lower layer 3;

[0068] S5. Under vacuum conditions, the upper surface of the lower layer 3 and the lower surface of the middle layer 2 are aligned and bonded to form a sealed cavity, and the bonding part between the lower layer 3 and the middle layer 2 is insulated.

[0069] S6. A pressure-sensitive membrane is formed on the upper surface of the upper layer 1;

[0070] S7. Fabricate the upper electrode 4 on the upper layer 1; fabricate the middle electrode 5 on the middle layer 2; fabricate the lower electrode 6 on the lower layer 3.

[0071] Preferably, the outer contours of the upper layer 1, the middle layer 2, and the lower layer 3 are the same. In this case, in order to form the upper electrode 4, the middle electrode 5, and the lower electrode 6, before step S7, the method further includes: cutting off a portion of the upper layer 1 to expose a portion of the upper surface of the middle layer 2, and cutting off a portion of the middle layer 2 to expose a portion of the upper surface of the lower layer 3.

[0072] Optionally, in step S7, an upper electrode 4 is formed on the upper surface of the upper layer 1; an intermediate electrode 5 is formed on the upper surface of the middle layer 2; and a lower electrode 6 is formed on the upper surface of the lower layer 3.

[0073] Preferably, the outer contour formed by the groove sidewall of the second groove 31 is the same as the outer contour formed by the groove sidewall of the first groove 11.

[0074] Optionally, in this embodiment, both the first groove 11 and the second groove 31 are quadrilateral grooves, the length of the second groove 31 is the same as the length of the first groove 11, and the width of the second groove 31 is the same as the width of the first groove 11.

[0075] For example, the depth of the second groove 31 is 3 μm.

[0076] Preferably, before step S1, the lower surface of the upper layer 1 is oxidized to form an oxide layer 100 to ensure an insulating connection between the bonding sites of the upper layer 1 and the intermediate layer 2. In other embodiments, the lower surface of the upper layer 1 may be oxidized after step S1 and before step S3 to form the oxide layer 100. In other embodiments, the bonding sites between the intermediate layer 2 and the upper layer 1 may be oxidized in step S3.

[0077] Preferably, after step S3 and before step S4, the upper surface of the lower layer 3 is oxidized to form an oxide layer 100 to ensure an insulating connection between the lower layer 3 and the bonding portion of the intermediate layer 2. In other embodiments, after step S4 and before step S5, the upper surface of the lower layer 3 is oxidized to form an oxide layer 100. In other embodiments, in step S5, the bonding portion between the intermediate layer 2 and the lower layer 3 is oxidized.

[0078] In one embodiment, in step S1: a boss 12 is fabricated on the surface of the upper layer 1 using photolithography and deep silicon etching processes; a silicon oxide insulating layer is grown on the surface of the upper layer 1 using thermal oxidation technology as an oxide layer 100, and patterned using photolithography and silicon oxide dry etching.

[0079] In one embodiment, in step S2: a resonator structure is fabricated on the intermediate layer 2 using photolithography and deep silicon etching processes.

[0080] In one embodiment, in step S3: after cleaning the upper layer 1 and the middle layer 2, the upper layer 1 and the middle layer 2 are aligned and bonded together using a bonding machine, and then bonded together to form a whole.

[0081] In one embodiment, in step S4: using photolithography and deep silicon etching processes, a second groove 31 with a depth of 3 μm is etched on the lower layer 3 to provide a deformation area for the pressure-sensitive film; using thermal oxidation technology, a silicon oxide insulating layer is grown on the surface of the lower layer 3 as an oxide layer 100, and patterned using photolithography and silicon etching of the oxide layer 100.

[0082] In one embodiment, in step S5, a spacer is inserted between the intermediate layer 2 and the lower layer 3. Then, the intermediate layer 2 and the lower layer 3 are fed into the vacuum chamber of the bonding machine. The spacer is removed, and the intermediate layer 2 and the lower layer 3 are aligned and bonded together by applying pressure and heating to form a sealed cavity. Specifically, in step S5: after cleaning the intermediate layer 2 and the lower layer 3, the two silicon wafers are aligned using the bonding machine. After inserting the spacer, the two silicon wafers are fed into the vacuum chamber of the bonding machine. Under high vacuum conditions, the spacer is removed, allowing the two silicon wafers to adhere. The two silicon wafers are then bonded together by applying pressure and heating to form a single unit.

[0083] In one embodiment, in step S6: the upper surface of the three-layer bonded silicon wafer is patterned using photolithography, and a pressure-sensitive film is formed using deep silicon etching.

[0084] In one embodiment, in step S7, an aluminum metal thin film used as an electrode is formed using electron beam evaporation deposition technology. In step S7: to expose the pad area of ​​the pressure sensor, the upper layer 1 is further cut using a dicing machine to peel off the area of ​​the upper layer 1 that is blocking the electrode of the intermediate layer 2; the intermediate layer 2 is then cut using a dicing machine to peel off the area of ​​the intermediate layer 2 that is blocking the electrode of the lower layer 3, thereby exposing the pad areas of the lower layer 3 and the intermediate layer 2, respectively.

[0085] In one embodiment, in step S8, a hard mask for three-layer electrode windows is fabricated and attached to the chip surface. An aluminum metal thin film is deposited in the electrode area using electron beam evaporation for lead connection.

[0086] The following example further illustrates the embodiment of the pressure sensor fabrication described above:

[0087] Step 1) Using P-type double-polished single crystal silicon as the upper layer 1, with a resistivity of 0.0005Ω.cm~0.001Ω.cm and a thickness of 300μm, the silicon is dry etched using thick photoresist as a mask to fabricate a boss 12 as an anchoring region for anode bonding. The boss 12 has a height of 3μm.

[0088] Step 2) Using thermal oxidation technology, the surface of the upper layer 1 is oxidized on both sides to a thickness of 0.5 μm. Adhesive is applied using a 3D spray adhesive device, and electrode windows are formed by photolithography. The oxide layer 100 is removed by HF etching to ensure that this area cannot bond with the intermediate layer 2.

[0089] Step 3) Using P-type double-polished single-crystal silicon as the intermediate layer 2, with a resistivity of 0.0005Ω·cm to 0.001Ω·cm and a thickness of 15μm, the silicon is dry-etched using thick photoresist as a mask to form a resonator structure.

[0090] Step 4) Using P-type double-polished single-crystal silicon as the lower layer 3, with a resistivity of 0.0005Ω.cm~0.001Ω.cm and a thickness of 300μm, the silicon is dry-etched using thick photoresist as a mask to create a pressure film patterned groove with a depth of 3μm, forming a detection electrode and providing vibration space for the resonator structure.

[0091] Step 5) Double-sided oxidation of the lower layer 3 is performed using thermal oxidation technology to form a silicon oxide insulating layer with a thickness of 0.5 μm, serving as oxide layer 100. Adhesive is sprayed onto the layer using 3D spraying equipment, electrode windows are formed by photolithography, and oxide layer 100 is etched using HF acid to prevent this area from bonding with the intermediate layer 2.

[0092] Step 6) Clean the three-layer silicon using RCA1 and RCA2 cleaning solutions. Then, activate the bonding surfaces using RIE.

[0093] Step 7) Use a bonding machine to align and bond the upper layer 1 and the middle layer 2, and place them into the bonding chamber. Heat to 450℃, apply pressure and bond for 1 hour, then gradually cool down to below 100℃ after bonding.

[0094] Step 8) Remove the bonded sheet and clean it, including RCA cleaning solution and RIE plasma activation. After aligning the bonded sheet with the lower layer 3, insert the spacer and load it into the bonding machine chuck, then transfer it into the bonding chamber.

[0095] Step 9) Under vacuum conditions (less than 0.01 mbar), remove the gasket to bring the two sheets into contact, and pressurize and heat to 450°C to complete the triplet bonding.

[0096] Step 10) Spin-coat photoresist onto the surface of the upper layer 1 of the bonding wafer, photolithography to form a pressure-sensitive film area, and use dry etching to form a third groove 13 with a depth of 200μm, which is the pressure-sensitive film.

[0097] Step 11) Use a dicing machine to cut the chip into a rectangle, and remove the unbonded areas between the upper layer 1 and the middle layer 2, and the unbonded areas between the middle layer 2 and the lower layer 3, so that the middle layer electrode area and the lower layer electrode area are exposed.

[0098] Step 12) Attach the hard mask corresponding to the three silicon electrode regions to the chip surface, and use electron beam evaporation to deposit an Al film on the electrode regions for lead connection. Generally, the aluminum film thickness is 1 μm or more.

[0099] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method of processing a pressure sensor, characterized by, The pressure sensor comprises an upper layer (1), a middle layer (2) and a lower layer (3), the upper layer (1), the middle layer (2) and the lower layer (3) are all semiconductors; the processing method of the pressure sensor comprises the following steps: S1, a first groove (11) is made on the lower surface of the upper layer (1) and a boss (12) is reserved in the first groove (11); S2, a resonator structure is made inside the middle layer (2), the middle layer (2) comprises a frame type part (21) and a cantilever part (22), one end of the cantilever part (22) is connected to the inside of the frame type part (21) to form a resonator structure; S3, the upper surface of the middle layer (2) is aligned and bonded with the lower surface of the upper layer (1), the free end of the resonator structure is bonded with the boss (12) of the upper layer (1), and the bonding part between the middle layer (2) and the upper layer (1) is insulatedly connected; S4, a second groove (31) is made on the upper surface of the lower layer (3); S5, under vacuum conditions, the upper surface of the lower layer (3) and the lower surface of the middle layer (2) are aligned and bonded to form a sealed cavity, and the bonding part between the lower layer (3) and the middle layer (2) is insulatedly connected; S6, a pressure sensitive film is made on the upper surface of the upper layer (1); S7, an upper electrode (4) is made on the upper layer (1), a middle electrode (5) is made on the middle layer (2), and a lower electrode (6) is made on the lower layer (3).

2. The method of processing a pressure sensor according to claim 1, wherein, Before step S1, the lower surface of the upper layer (1) is subjected to oxidation treatment; or After step S1 and before step S3, the lower surface of the upper layer (1) is subjected to oxidation treatment; or In step S3, the bonding part between the middle layer (2) and the upper layer (1) is subjected to oxidation treatment.

3. The method of claim 1, wherein Before step S3 and after step S4, the upper surface of the lower layer (3) is subjected to oxidation treatment; or Before step S4 and after step S5, the upper surface of the lower layer (3) is subjected to oxidation treatment; or In step S5, the bonding part between the middle layer (2) and the lower layer (3) is subjected to oxidation treatment.

4. The method of claim 1, wherein The outer contour of the upper layer (1), the outer contour of the middle layer (2) and the outer contour of the lower layer (3) are the same, and before step S7, further comprising: cutting part of the upper layer (1) to expose part of the upper surface of the middle layer (2), and cutting part of the middle layer (2) to expose part of the upper surface of the lower layer (3).

5. The method of claim 4, wherein the pressure sensor is a diaphragm pressure sensor. In step S7, the upper electrode (4) is made on the upper surface of the upper layer (1), the middle electrode (5) is made on the upper surface of the middle layer (2), and the lower electrode (6) is made on the upper surface of the lower layer (3).

6. The method of claim 1, wherein The outer contour formed by the groove side wall of the second groove (31) is the same as the outer contour formed by the groove side wall of the first groove (11).

7. The method of claim 1, wherein In step S5, a gasket is inserted between the intermediate layer (2) and the lower layer (3), and then the intermediate layer (2) and the lower layer (3) are sent into a vacuum chamber of a bonder, the gasket is taken out, and the intermediate layer (2) and the lower layer (3) are aligned and bonded into one by pressurization and temperature rise, so as to form the sealed cavity.

8. The method of claim 1, wherein In step S7, an aluminum metal film used as an electrode is formed by using an electron beam evaporation deposition technology.

9. A pressure sensor, characterized by The pressure sensor comprises an upper layer (1), an intermediate layer (2) and a lower layer (3), and the upper layer (1), the intermediate layer (2) and the lower layer (3) are all semiconductors. A first recess (11) is formed on a lower surface of the upper layer (1), and a boss (12) is protruded in the first recess (11); The intermediate layer (2) comprises a frame-shaped portion (21) and a cantilever portion (22), one end of the cantilever portion (22) is connected to the inside of the frame-shaped portion (21) to form a resonator structure; an upper surface of the frame-shaped portion (21) is insulatively bonded to a lower surface of the upper layer (1), and a free end of the cantilever portion (22) is insulatively bonded to the boss (12); A second recess (31) is formed on an upper surface of the lower layer (3), and a lower surface of the frame-shaped portion (21) is insulatively bonded to the upper surface of the lower layer (3) to form a sealed cavity; An upper electrode (4) is arranged on the upper layer (1), an intermediate electrode (5) is arranged on the intermediate layer (2), and a lower electrode (6) is arranged on the lower layer (3).

10. The pressure sensor of claim 9, wherein, A lower surface of the boss (12) is located on the same horizontal plane as a lower surface of the upper layer (1).

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