MEMS pressure sensor and manufacturing method thereof

Abstract

The invention provides an MEMS pressure sensor and a preparation method thereof. The MEMS pressure sensor includes: a functional substrate; and the packaging layer is packaged on the surface of the functional substrate and is used for packaging the functional substrate, and the material of the packaging layer comprises polyether-ether-ketone. Therefore, the polyetheretherketone and the functional substrate have better binding force, higher strength, strong antistatic capability and good wear resistance and corrosion resistance, the pressure sensor can be effectively protected from being influenced by the external environment, the pressure sensor can normally work in a severe environment, the performance is kept stable, and the service life is prolonged.

Description

Technical Field

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

[0002] MEMS pressure sensors are sensitive to the external environment, and the key to the protection of the membrane layer in harsh environments is good stability. Traditional protective layer materials such as polyimide and epoxy resin are not suitable for MEMS devices in high-temperature environments due to their poor high-temperature resistance, which limits their application space. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a MEMS pressure sensor, which has good packaging properties and is conducive to improving its stability or extending its service life.

[0004] In one aspect of the present invention, the present invention provides a MEMS pressure sensor. According to an embodiment of the present invention, the MEMS pressure sensor includes: a functional substrate; a packaging layer, the packaging layer is packaged on the surface of the functional substrate, used to package the functional substrate, and the material of the packaging layer includes polyetheretherketone. As a result, polyetheretherketone has better bonding force with the functional substrate, higher strength, strong antistatic ability, good wear resistance and corrosion resistance, can effectively protect the pressure sensor from the external environment, can make the pressure sensor work normally in a harsh environment, maintain stable performance and extend service life.

[0005] According to an embodiment of the present invention, the thickness of the encapsulation layer is 70-100 micrometers.

[0006] According to an embodiment of the present invention, the hardness of the encapsulation layer is 22HV to 30HV.

[0007] According to an embodiment of the present invention, the surface resistivity of the encapsulation layer is 1×10 14 Ω.cm~9.99×10 14 Ω.cm.

[0008] According to an embodiment of the present invention, the bonding force between the encapsulation layer and the functional substrate is 50N-60N.

[0009] According to an embodiment of the present invention, the functional substrate includes: a substrate, the substrate having a first surface and a second surface arranged opposite to each other, the first surface having a back cavity; at least one varistor, the varistor being arranged on the second surface, and the orthographic projection of the varistor on the substrate overlaps with the back cavity; at least one lead, the lead being located on the second surface and electrically connected to the varistor; at least one contact resistor, the contact resistor being located on a side of the lead away from the substrate and electrically connected to the lead; an insulating layer, the insulating layer covering the second surface and the lead, a cavity being provided between the varistor and the insulating layer, and the insulating layer having at least one through hole, the through hole exposing the contact resistor; an electrode layer, the electrode layer being arranged on a side of the insulating layer away from the substrate, and electrically connected to the contact resistor through the through hole, and the encapsulation layer filling the through hole and encapsulating on a surface of the electrode layer away from the substrate.

[0010] In another aspect of the present invention, the present invention provides a method for manufacturing the aforementioned MEMS pressure sensor. According to an embodiment of the present invention, the method for manufacturing a MEMS pressure sensor includes: spraying a packaging layer on the surface of a functional substrate, and the material of the packaging layer includes polyetheretherketone. Therefore, in the manufacturing method, polyetheretherketone is used as the packaging material, and polyetheretherketone has better bonding with the functional substrate, higher strength, strong antistatic ability, good wear resistance and corrosion resistance, and can effectively protect the pressure sensor from the external environment, so that the pressure sensor can work normally in a harsh environment, maintain stable performance and extend service life.

[0011] According to an embodiment of the present invention, at least one of the following conditions is met during the spraying process: the vertical distance between the spray gun nozzle and the surface of the functional substrate is 20 to 30 cm; the translation rate of the spray gun is 200 mm / s to 300 mm / s; and the powder spraying amount is 5 g / min to 15 g / min.

[0012] According to an embodiment of the present invention, the method for manufacturing a MEMS pressure sensor further includes: before spraying the packaging layer, pre-roughening the surface of the functional substrate.

[0013] According to an embodiment of the present invention, the roughening process is laser processing.

[0014] According to an embodiment of the present invention, the laser processing conditions satisfy at least one of the following conditions: the wavelength is 800nm-1900nm; the pulse width is 400fs-800fs; the moving speed of the laser source is 200mm / s-300mm / s.

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

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0017] Figure 1 is a schematic diagram of the structure of a MEMS pressure sensor in one embodiment of the present invention;

[0018] Figure 2 is a schematic structural diagram of a MEMS pressure sensor in another embodiment of the present invention;

[0019] Figure 3 It is a schematic structural diagram of a MEMS pressure sensor in another embodiment of the present invention. Description of the drawings:

[0021] Packaging layer 100 ; functional substrate 200 ; substrate 210 ; back cavity 211 ; varistor 220 ; lead 230 ; contact resistor 240 ; insulating layer 250 ; through hole 251 ; electrode layer 260 ; pore 101 . DETAILED DESCRIPTION

[0022] The scheme of the present invention will be explained below in conjunction with the embodiments. It will be appreciated by those skilled in the art that the following embodiments are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used are not indicated by the manufacturer and are all conventional products that can be obtained commercially.

[0023] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0024] In one aspect of the present invention, the present invention provides a MEMS pressure sensor. According to an embodiment of the present invention, referring to Figure 1The MEMS pressure sensor includes: a functional substrate 200; a packaging layer 100, wherein the packaging layer 100 is packaged on the surface of the functional substrate 200 and is used to package the functional substrate 200, and the material of the packaging layer 100 includes polyetheretherketone (PEEK). Therefore, polyetheretherketone has a better bonding force with the functional substrate, higher strength, strong antistatic ability, good wear resistance and corrosion resistance, and can effectively protect the pressure sensor from the external environment, so that the pressure sensor can work normally in a harsh environment, maintain stable performance and extend service life; and polyetheretherketone is easy to purchase and has a wide source, which is conducive to reducing production costs and facilitating industrial mass production.

[0025] According to the embodiment of the present invention, polyetheretherketone is resistant to high temperature, has excellent mechanical properties, good self-lubrication, chemical corrosion resistance, flame retardancy, peeling resistance, radiation resistance, hydrolysis resistance and easy processing, and has good insulation and dielectric properties. The molecular structure of polyetheretherketone is When applied to the packaging layer of MEMS pressure sensors, the benzene ring on its molecular chain segment shows good rigidity, the ether bond shows good flexibility, and the carbonyl group shows a higher interaction force between molecules. Therefore, the packaging layer of polyetheretherketone material can effectively improve the mechanical properties of the packaging layer, and also has good antistatic properties and other properties.

[0026] According to some embodiments of the present invention, the thickness of the packaging layer D is 70 to 100 microns, for example, the thickness of the packaging layer is 70 microns, 72 microns, 75 microns, 78 microns, 80 microns, 82 microns, 85 microns, 88 microns, 90 microns, 93 microns, 95 microns, 98 microns, 100 microns, etc. The packaging layer of the above thickness is suitable, which will not make the overall thickness of the pressure sensor too thick, and can achieve a good packaging effect and ensure its performance stability; and the obtained packaging layer has a more uniform thickness and better quality. It should be noted that the thickness of the above packaging layer refers to the thickness of the packaging layer at the non-through hole.

[0027] According to some embodiments of the present invention, the hardness of the encapsulation layer is 22HV to 30HV, such as 22HV, 23HV, 24HV, 25HV, 26HV, 27HV, 28HV, 29HV, 30HV, etc. It can be seen that the encapsulation layer of the present invention has better mechanical properties, which helps to improve the friction resistance of the pressure sensor and improve its performance stability.

[0028] It should be noted that the above hardness data of the present invention is obtained by testing the hardness of the surface of the packaging layer using a microhardness tester. The test load is 0.05 kg. The load is released after 15 seconds and the data is read. Each sample is tested 5 times and the average value is taken to obtain the above hardness data.

[0029] According to some embodiments of the present invention, the bonding force between the encapsulation layer and the functional substrate is 50N-60N, for example, the bonding force is 50N, 51N, 52N, 53N, 54N, 55N, 56N, 57N, 58N, 59N, 60N, etc. It can be seen that the encapsulation layer of the present invention has better mechanical properties, which helps to improve the friction resistance of the pressure sensor and improve its performance stability.

[0030] It should be noted that the above-mentioned bonding force data of the present invention is obtained by scratch test. In the test, the loading force is 0-70N, the loading time is 30s, the scratch is 3mm, and the bonding force is judged according to the scratch morphology. The calculation method is: bonding force = (L1 / L2) × 70N, L1 is the distance from the coating peeling position to the scratch starting position, and L2 is the total length of the scratch.

[0031] According to some embodiments of the present invention, the surface resistivity of the encapsulation layer is 1×10 14 Ω.cm~9.99×10 14 Ω.cm, for example, the surface resistivity is 1×10 14 Ω.cm、1.5×10 14 Ω.cm, 2×10 14 Ω.cm、2.5×10 14 Ω.cm、3×10 14 Ω.cm、3.5×10 14 Ω.cm、4×10 14 Ω.cm、4.35×10 14 Ω.cm、5×10 14 Ω.cm、5.5×10 14 Ω.cm、6×10 14 Ω.cm、6.5×10 14 Ω.cm、7×10 14 Ω.cm、7.5×10 14 Ω.cm、8×10 14 Ω.cm、8.5×10 14 Ω.cm、9×10 14 Ω.cm、9.5×10 14 Ω.cm、9.5×10 14 Ω.cm、9.99×10 14 Ω.cm, etc. Therefore, the packaging layer with the above surface resistivity can effectively leak the charge, thereby improving the anti-static ability of the pressure sensor.

[0032] It should be noted that the above-mentioned surface resistivity of the present invention is measured by an insulation resistance measuring instrument in accordance with the method specified in the national standard GB / T15662-1995. Air is used as the environmental medium, and the surface resistivity is measured at a voltage of 100V. The formula: Rs=ρs(d / L) is used for calculation. Each group of samples is tested 5 times and the average value is taken as the test result.

[0033] According to an embodiment of the present invention, the friction coefficient of polyetheretherketone is 0.25, which is 50% lower than the friction coefficient (0.5) of polyimide commonly used in the prior art. This can make the pressure sensor have better wear resistance, effectively resist the influence of the external environment, and maintain good performance stability.

[0034] In the existing technical means, polyimide material or epoxy resin is often used as the encapsulation layer. In some examples, under the same conditions as the present invention, polyimide material is used as the encapsulation layer, the thickness is 80 microns, the hardness of the polyimide encapsulation layer is 22HV, the bonding force is 45N, and the surface resistivity is 3.92×10 15 Ω.cm. By comparison, it can be seen that compared with polyimide, the encapsulation layer of the present invention has better mechanical properties and relatively low surface resistivity, which can better improve the stability and antistatic ability of the pressure sensor. If epoxy resin is used to coat the encapsulation layer, the prepared encapsulation layer has low density, poor high temperature resistance, insufficient wear resistance, corrosion resistance and antistatic ability, and cannot protect the pressure sensor well.

[0035] According to some embodiments of the present invention, referring to Figure 1The functional substrate 200 includes: a substrate 210, the substrate 210 has a first surface and a second surface arranged opposite to each other, the first surface has a back cavity 211; at least one varistor 220, the varistor 200 is arranged on the second surface, and the positive projection of the varistor 220 on the substrate 100 overlaps with the back cavity 211; at least one lead 230, the lead 230 is located on the second surface and is electrically connected to the varistor 220; at least one contact resistor 240, the contact resistor 240 is located on the side of the lead 230 away from the substrate, and is connected to the lead The varistor 220 and the lead 230 are electrically connected; the insulating layer 250 covers the second surface and the lead 230, a cavity 225 is provided between the varistor 220 and the insulating layer 250, and the insulating layer 250 has at least one through hole 251, and the through hole 251 exposes the contact resistor 240; the electrode layer 260 is arranged on the side of the insulating layer 250 away from the substrate 210, and is electrically connected to the contact resistor 240 through the through hole 251, and the encapsulation layer 100 fills the through hole 251 and is encapsulated on the surface of the electrode layer 260 away from the substrate 100. In this way, the encapsulation layer not only encapsulates the functional substrate 200, but also fills the through hole, so that the contact area between the encapsulation layer and the electrode is increased, which can help to further improve the bonding force between the encapsulation layer and the functional substrate; moreover, the adhesion between the polyetheretherketone and the metal material of the electrode layer is good, and its expansion coefficient is small, which can effectively prevent the occurrence of the undesirable phenomenon of abnormal hole connection function due to the mismatch between the stress and the electrode layer.

[0036] Further, in some specific embodiments, in the positional relationship between the contact resistor 240 and the through hole 251, the contact resistor 240 is located inside the through hole 251, that is, the contact resistor 240 is located at the center of the bottom of the through hole 251, and the area of ​​the contact resistor 240 is smaller than the area of ​​the bottom of the through hole 251, such as Figure 2 shown.

[0037] In some embodiments, the number of varistors, leads, contact resistors, and through holes is substantially the same and arranged in a one-to-one correspondence, such as Figure 1 As shown, a varistor is provided with leads, contact resistors and corresponding through holes.

[0038] In some embodiments, the orthographic projection of the piezoresistor 220 on the substrate 100 is located in the back cavity 211 , so that the piezoresistor can sense stress more sensitively, thereby improving the sensitivity of the pressure sensor.

[0039] In some embodiments, there is no special requirement for the specific height of the cavity, and those skilled in the art can flexibly set it according to actual needs, and the requirements are not limited here.

[0040] In some embodiments, the substrate 210 may be made of glass, metal, or polymer.

[0041] In some embodiments, there is no special requirement for the specific material of the varistor, and those skilled in the art can flexibly select it according to existing technical means. In some specific embodiments, the material of the varistor includes zinc oxide.

[0042] In some embodiments, there are no special requirements for the specific material of the lead wire, and those skilled in the art can flexibly select it based on existing technical means. For example, it can be a conductive metal such as copper, silver, aluminum, and titanium.

[0043] In some embodiments, there are no special requirements for the specific material of the insulating layer, and those skilled in the art can flexibly select it based on existing technical means, for example, it can be glass.

[0044] In some embodiments, the material of the electrode layer includes but is not limited to metals such as copper, silver, and aluminum.

[0045] According to some embodiments of the present invention, the above refers to an example of a functional substrate structure, and is not a limitation on the pressure sensor structure of the present invention. The packaging layer structure, i.e., the material, of the present invention can be applied to any existing pressure sensor structure.

[0046] In another aspect of the present invention, the present invention provides a method for manufacturing the aforementioned MEMS pressure sensor. According to an embodiment of the present invention, the method for manufacturing a MEMS pressure sensor includes: spraying a packaging layer on the surface of a functional substrate, and the material of the packaging layer includes polyetheretherketone. Therefore, in the manufacturing method, polyetheretherketone is used as a packaging material, and after cooling after spraying, a dense, smooth, and flat packaging layer can be obtained, and polyetheretherketone has better bonding with the functional substrate, higher strength, strong antistatic ability, good wear resistance and corrosion resistance, and can effectively protect the pressure sensor from the external environment, so that the pressure sensor can work normally in a harsh environment, maintain stable performance and extend service life.

[0047] According to some embodiments of the present invention, the specific process of preparing the encapsulation layer by spraying may be thermal spraying or electrostatic spraying. In some specific embodiments, the encapsulation layer may be prepared by thermal spraying.

[0048] According to some embodiments of the present invention, in the spraying process, dense polyetheretherketone powder particles are melted at high temperature and then evenly sprayed on the surface of the functional substrate for through-hole filling and surface coating. In some embodiments, the particle size of the polyetheretherketone powder particles used can be 800-1000 mesh, so that it is easy to be heated evenly and fully melted.

[0049] According to some embodiments of the present invention, the vertical distance between the spray gun port and the surface of the functional substrate is 20-30 cm, such as 20 cm, 21 cm, 22 cm, 23 cm, 24 cm, 25 cm, 26 cm, 27 cm, 28 cm, 29 cm, 30 cm, etc. In this way, it is easy to prepare a packaging layer with good quality and performance.

[0050] According to some embodiments of the present invention, the translation rate of the spray gun is 200mm / s to 300mm / s, for example, 200mm / s, 205mm / s, 210mm / s, 215mm / s, 220mm / s, 225mm / s, 230mm / s, 235mm / s, 240mm / s, 245mm / s, 250mm / s, 255mm / s, 260mm / s, 265mm / s, 270mm / s, 275mm / s, 280mm / s, 285mm / s, 290mm / s, 295mm / s, 300mm / s, etc. The translation speed of the spray gun is conducive to obtaining a packaging layer with good sealing and good density; if the translation speed of the spray gun is relatively fast, that is, greater than 300 mm / s, the packaging layer is not uniform and has poor density, similar to a non-filled state, and there are more pores 101 in the packaging layer, such as Figure 3 As shown, this will seriously affect the density of the packaging layer, and may relatively reduce its mechanical properties; if the translation rate of the spray gun is relatively slow, that is, less than 200mm / s, the accumulation of the packaging layer material will cause the thickness to be relatively large and uneven, making the surface relatively uneven, thereby affecting the wear resistance of the pressure sensor.

[0051] According to some embodiments of the present invention, the powder spraying amount during spraying is 5g / min to 15g / min, such as 5g / min, 6g / min, 7g / min, 8g / min, 9g / min, 10g / min, 11g / min, 12g / min, 13g / min, 14g / min, 15g / min, etc. The above powder spraying amount is conducive to obtaining a packaging layer with good sealing and good density; if the powder spraying amount is relatively small, that is, less than 5g / min, the packaging layer is not uniform and has poor density, similar to a non-filled state, and there are more pores 101 in the packaging layer, such as Figure 3 As shown, this will seriously affect the density of the packaging layer, and may relatively reduce its mechanical properties; if the powder spraying amount is relatively large, that is, greater than 15g / min, the accumulation of the packaging layer material will cause the thickness to be relatively large and uneven, making the surface relatively uneven, thereby affecting the wear resistance of the pressure sensor.

[0052] According to some embodiments of the present invention, the method for manufacturing a MEMS pressure sensor further includes: roughening the surface of the functional substrate before spraying the packaging layer. In some embodiments, the surface of the electrode layer is roughened. This helps to improve the bonding force between the packaging layer and the functional substrate.

[0053] According to some embodiments of the present invention, the roughening treatment is laser treatment, which can effectively improve the roughness of the surface of the electrode layer, and the process is easy to control and implement, and does not damage other structures of the pressure sensor.

[0054] According to some embodiments of the present invention, the wavelength of the laser is 800nm~1900nm, the pulse width is 400fs~800fs, such as 400fs, 450fs, 500fs, 550fs, 600fs, 650fs, 700fs, 750fs, 800fs, etc., and the moving speed of the laser source is 200mm / s~300mm / s, such as 200mm / s, 205mm / s, 21 0mm / s, 215mm / s, 220mm / s, 225mm / s, 230mm / s, 235mm / s, 240mm / s, 245mm / s, 250mm / s, 255mm / s, 260mm / s, 265mm / s, 270mm / s, 275mm / s, 280mm / s, 285mm / s, 290mm / s, 295mm / s, 300mm / s, etc. Therefore, the laser treatment under the above conditions can obtain a suitable roughness, which is beneficial to improving the bonding force between the packaging layer and the functional substrate without causing adverse damage to other structures.

[0055] In some specific embodiments, the wavelength of the laser is 1030 nm and the pulse width is 600 fs.

[0056] According to some embodiments of the present invention, the above-mentioned MEMS pressure sensor can be used in various fields such as 5G, computers, iPads, smart phones, automotive electronics, artificial intelligence, etc.

[0057] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0058] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0059] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A MEMS pressure sensor, characterized in that: include: Functional substrate; The encapsulation layer is encapsulated on the surface of the functional substrate and is used to encapsulate the functional substrate, and the material of the encapsulation layer includes polyetheretherketone.

2. The MEMS pressure sensor according to claim 1, characterized in that: The thickness of the packaging layer is 70 to 100 microns.

3. The MEMS pressure sensor according to claim 1, characterized in that: The hardness of the packaging layer is 22HV to 30HV.

4. The MEMS pressure sensor according to claim 1, characterized in that: The surface resistivity of the encapsulation layer is 1×10 14 Ω.cm~9.99×10 14 Ω.cm.

5. The MEMS pressure sensor according to claim 1, characterized in that: The bonding force between the packaging layer and the functional substrate is 50N-60N.

6. The MEMS pressure sensor according to claim 1, characterized in that: The functional substrate comprises: A substrate, the substrate having a first surface and a second surface arranged opposite to each other, the first surface having a back cavity; at least one varistor, wherein the varistor is disposed on the second surface, and an orthographic projection of the varistor on the substrate overlaps with the back cavity; at least one lead, the lead being located on the second surface and electrically connected to the varistor; at least one contact resistor, the contact resistor being located on a side of the lead away from the substrate and electrically connected to the lead; an insulating layer, the insulating layer covering the second surface and the lead, a cavity being provided between the varistor and the insulating layer, and the insulating layer having at least one through hole, wherein the through hole exposes the contact resistor; an electrode layer, the electrode layer being arranged on a side of the insulating layer away from the substrate and being electrically connected to the contact resistor through the through hole, The encapsulation layer fills the through hole and is encapsulated on the surface of the electrode layer away from the substrate.

7. A method for manufacturing the MEMS pressure sensor according to any one of claims 1 to 6, characterized in that: include: A packaging layer is sprayed on the surface of the functional substrate, and the material of the packaging layer includes polyetheretherketone.

8. The method according to claim 7, characterized in that During the spraying process, at least one of the following conditions is met: The vertical distance between the spray gun mouth and the surface of the functional substrate is 20 to 30 cm; The translation speed of the spray gun is 200mm / s~300mm / s; The powder spraying amount is 5g / min~15g / min.

9. The method according to claim 7 or 8, characterized in that: Also includes: Before spraying the encapsulation layer, the surface of the functional substrate is roughened in advance.

10. The method according to claim 9, characterized in that The roughening process is laser processing.

11. The method according to claim 10, characterized in that The laser treatment conditions satisfy at least one of the following conditions: Wavelength: 800nm~1900nm; Pulse width is 400fs~800fs; The moving speed of the laser source is 200 mm / s to 300 mm / s.

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