A silicon-metal composite MEMS material atmospheric corrosion sensor, its preparation method, and an atmospheric corrosion detection device for materials

Abstract

The present application provides a silicon-metal composite MEMS material atmospheric corrosion sensor, a preparation method thereof, and a material atmospheric corrosion detection device, which relate to the field of material corrosion sensors. The silicon-metal composite MEMS material atmospheric corrosion sensor includes a cathode-anode module and a cavity structure module; the cathode-anode module includes a first substrate and independent metal anodes and metal cathodes disposed on the surface of the first substrate; the cavity structure module includes a second substrate, the second substrate is provided with a recess and a through hole for communicating with the test environment atmosphere, the recess extends from a first side of the second substrate to a second side opposite thereto, and the through hole extends from the surface of the second side to the bottom of the recess; the surface of the second side abuts against the surface of the first substrate, and the metal cathodes and the metal anodes are disposed in the recess. The sensor provided by the present application has good sensitivity, reliability and consistency.

Description

Technical Field

[0001] This application relates to the technical field of material corrosion sensors, and particularly to a silicon-metal composite MEMS material atmospheric corrosion sensor, a preparation method thereof, and a material atmospheric corrosion detection device. Background Art

[0002] Material corrosion is one of the important reasons for the failure of metal structural components. Especially in the microelectronics industry, the corrosion failure of electronic device materials will directly threaten the service life of industrial equipment, and in severe cases, it may even lead to information security problems. Device-level material corrosion monitoring is one of the key technologies for analyzing the causes of device corrosion failure, judging the state of material corrosion failure, and predicting the corrosion failure life of devices. Traditional corrosion monitoring technologies use mechanical structure sensors, which cannot achieve device-level material corrosion monitoring. At the same time, they have the characteristics of large volume, low precision, high cost, and difficulty in mass production, and cannot achieve large-scale monitoring of electronic device corrosion failure. With the continuous progress of technology and the continuous development of society in recent years, MEMS (Micro-Electro-Mechanical Systems) has been greatly developed. Correspondingly, as MEMS sensors have also been greatly developed, and they have been widely used in fields such as automobiles, security, biomedicine, electric power, smart buildings, forest fire prevention, smartphones, and the Internet of Things. However, MEMS sensors suitable for material corrosion have been in an undeveloped state due to technical reasons. Therefore, this application uses micro-machining processes to achieve device-level material corrosion monitoring, which is very important for the development of material corrosion big data technology and the development of MEMS sensors. Summary of the Invention

[0003] The purpose of this application is to provide a silicon-metal composite MEMS material atmospheric corrosion sensor, a preparation method thereof, and a material atmospheric corrosion detection device to solve the problems of poor stability, low repeatability, and difficulty in mass production of existing mechanical atmospheric corrosion sensors.

[0004] To achieve the above purpose, this application adopts the following technical solutions:

[0005] A silicon-metal composite MEMS material atmospheric corrosion sensor includes a cathode-anode module and a cavity structure module;

[0006] The cathode-anode module includes a first substrate and independent metal anodes and metal cathodes disposed on the surface of the first substrate;

[0007] The cavity structure module includes a second substrate, the second substrate is provided with a recess and a through hole for communicating with the test environment atmosphere, the recess extends from a first side of the second substrate to an opposite second side, and the through hole extends from the surface of the second side to the bottom of the recess;

[0008] The surface of the second side abuts against the surface of the first substrate, and the metal cathode and the metal anode are disposed within the recessed portion;

[0009] The material of the metal anode is the metal material to be measured, and the material of the metal cathode is coupled with the metal material to be measured;

[0010] The distance between the metal anode and the metal cathode is 10 - 100 μm.

[0011] When the distance is too small, short circuits are likely to occur when corrosive products with conductive properties or particulate matter with wire properties in the air are deposited; while when the distance is too large, the sensor will be insensitive to changes in environmental corrosivity, greatly reducing the sensitivity of the sensor. Considering comprehensively, the distance between the metal anode and the metal cathode should be controlled between 10 microns and 100 microns.

[0012] Preferably, the first substrate and the second substrate are each independently a silicon wafer or glass.

[0013] Preferably, the first substrate is a silicon wafer, the second substrate is glass, the metal material to be measured is stainless steel, and the material of the metal cathode is copper.

[0014] This application also provides a preparation method of the silicon-metal composite MEMS material atmospheric corrosion sensor as described above, including:

[0015] Bond the sheet-shaped metal material to be measured with the first substrate to obtain a substrate-metal composite sheet;

[0016] Apply photoresist on the surface of the substrate-metal composite sheet, then use a mask plate with a metal anode pattern for exposure, development, and fixing to form a metal anode target pattern; use the metal anode target pattern for etching until the first substrate is revealed, and then remove the residual photoresist to obtain a first composite sheet;

[0017] Apply photoresist on the side of the first composite sheet having the metal anode, use a mask plate with a metal cathode pattern for exposure, development, and fixing to form a metal cathode target pattern to obtain a second composite sheet; adopt a sputtering method to sputter the cathode material on the second composite sheet, and then remove the residual photoresist and cathode material on the second composite sheet to obtain the anode-cathode module;

[0018] A photoresist is disposed on the first side of the second substrate, and then exposure, development, and fixing are performed using a mask plate with the pattern of the recessed portion to form a target pattern of the recessed portion; etching is performed using the target pattern of the recessed portion until the recessed portion is formed; the remaining photoresist is removed, and then a photoresist is disposed on the second side, and then exposure, development, and fixing are performed using a mask plate with the pattern of the through hole to form a target pattern of the through hole; etching is performed using the target pattern of the through hole until the through hole is formed, and the remaining photoresist is removed to obtain the cavity structure module;

[0019] The metal anode and the metal cathode of the anode-cathode module are disposed in the recessed portion of the cavity structure module, and then the surface of the second side of the first substrate is connected to the surface of the first substrate.

[0020] Preferably, the bonding is performed using a two-component polydimethylsiloxane adhesive.

[0021] Preferably, when etching is performed using the metal anode target pattern, the etchant includes:

[0022] HCl 2.7 - 5.4 mol / L, hydrogen peroxide 4.4 - 7.4 mol / L, corrosion inhibitor 1 - 10 g / L, dispersant 20 - 50 g / L, hydrogen peroxide stabilizer 5 - 10 g / L.

[0023] Preferably, the connection includes:

[0024] The surface of the second side and the surface of the first substrate are chemically cleaned and activated using a wet chemical treatment method;

[0025] The first substrate is connected to the positive electrode of the power supply, the second substrate is connected to the negative electrode of the power supply, the temperature is raised to 300 - 500 °C, and a bias voltage of more than 500 V is applied to complete the bonding of the first substrate and the second substrate by the generated electrostatic force.

[0026] The present application also provides a material atmospheric corrosion detection device, including the silicon-metal composite MEMS material atmospheric corrosion sensor described above.

[0027] Preferably, the material atmospheric corrosion detection device further includes a signal processing module electrically connected to the silicon-metal composite MEMS material atmospheric corrosion sensor, and the signal processing module includes an ASIC chip with the ability to detect microcurrent and microvoltage.

[0028] Preferably, the material atmospheric corrosion detection device further includes a lead frame structure capable of carrying the silicon-metal composite MEMS material atmospheric corrosion sensor and the ASIC chip.

[0029] Compared with the prior art, the beneficial effects of the present application include:

[0030] The silicon-metal composite MEMS material atmospheric corrosion sensor provided by the present application optimizes the performance of the material corrosion sensor by setting a material corrosion electrochemically sensitive material on a non-metal substrate and integrating the material corrosion sensitive element and the electric quantity detection module, which can greatly improve the sensitivity, reliability and consistency of the material corrosion sensor.

[0031] The present application adopts the manufacturing process of the silicon-metal composite MEMS atmospheric environment corrosion sensor. By bonding silicon and metal materials together, and then etching a working metal electrode (anode) for corrosion monitoring on the metal through an etching method, and subsequently sputtering a counter electrode and a reference electrode (cathode) on the silicon substrate through a sputtering method. The present application not only solves the problem that there are differences in the composition and organizational structure between traditional sputtered metal sensors and machined sensors, but also solves the problems of small size, uniformity, high stability and batch manufacturing. The related technology can promote the wider application of MEMS atmospheric environment corrosion sensors in various high-precision on-line monitoring scenarios of material atmospheric corrosion.

[0032] The material atmospheric corrosion detection equipment provided by the present application includes two major parts: microfabrication technology and microelectronics technology. One part is to convert material corrosion into signal changes such as capacitance, resistance, and current through a MEMS chip, and the other part is to convert signal changes such as capacitance, resistance, and inductance into electrical signals through an ASIC chip, thereby realizing the function of the MEMS corrosion sensor - converting material corrosion signals into electrical signals. Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope of the present application.

[0034] Figure 1 Schematic diagram of the bonding of a silicon wafer and a metal sheet;

[0035] Figure 2 Schematic diagram of the preparation of a MEMS sensor;

[0036] Figure 3 Schematic diagram of a cavity structure;

[0037] Figure 4 Front view of a MEMS sensor;

[0038] Figure 5 Top view of a MEMS sensor;

[0039] Figure 6 Three-dimensional view of a MEMS sensor.

[0040] Reference numerals:

[0041] 1 - Metal anode, 2 - Silicon wafer, 3 - PDMS adhesive, 4 - Metal cathode, 5 - Glass sheet, 6 - Through hole. Detailed implementation manners

[0042] The following will describe in detail the implementation schemes of the present application in combination with specific embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0043] Example 1

[0044] This example provides a silicon - metal composite MEMS material atmospheric corrosion sensor, including a cathode - anode module and a cavity structure module; the cathode - anode module includes a silicon wafer and independent metal anodes and metal cathodes provided on the surface of the silicon wafer; the cavity structure module includes a glass sheet, the glass sheet is provided with a recess and a through hole for communicating with the test environment atmosphere, the recess extends from the first side of the glass sheet to the opposite second side, and the through hole extends from the surface of the second side to the bottom of the recess; the surface of the second side is bonded to the surface of the silicon wafer, and the metal cathode and the metal anode are arranged in the recess.

[0045] Its preparation method is as follows:

[0046] (1) Preparation of the metal anode 1

[0047] 5.1 Refer to Figure 1 , Figure 1 , which is a schematic diagram of the bonding of a silicon wafer and a metal sheet. As shown in Figure 1 , select a silicon wafer 2, specifically select a 4 - inch (φ100.84 mm) wafer as the substrate material, select 316L stainless steel as the metal anode material, cut the 316L stainless steel into a size of φ100.84 mm × 300 μm, polish the surface of the stainless steel step by step with SiC sandpaper to 5000#, and polish it step by step with Al2O3 polishing paste to a particle size of 1 μm, clean it with deionized water and high - purity alcohol, and dry it for later use.

[0048] 5.2 The silicon wafer 2 and 316L stainless steel are bonded using a PDMS adhesive 3 (polydimethylsiloxane two-component adhesive). First, the two components of liquid component A (PDMS prepolymer) and component B (curing agent) are completely mixed at a weight ratio of 10:1 to form a mixed liquid with medium viscosity. Subsequently, it is evenly coated on the surface of the silicon wafer and 316L stainless steel, and the two are concentrically bonded and placed on a heating table. The temperature of the heating table is adjusted to 100 °C and cured for 35 minutes to fully cure the PDMS adhesive.

[0049] 5.3 An acidic cleaning solution is prepared by mixing 30% hydrochloric acid and ultrapure water at a volume ratio of 1:1 to remove the surface oxides of 316L stainless steel. After that, the silicon-316L stainless steel sheet is rinsed with a large amount of deionized water and dried using a high-speed spin-drying device. The spin-drying process takes 300 s.

[0050] 5.4 Refer to Figure 2 , the silicon wafer 2 is coated with SU-8 semiconductor ultraviolet photoresist. The SU-8 photoresist components are evenly spin-coated on the substrate at a speed of 1000 r / min, and the spin-coated thickness is controlled at 120 microns. After being fully dried by heating the silicon wafer on a uniform heating plate at 80 to 120 °C for 120 s, it is transferred to a lithography machine, and a mask plate of the anode metal material is loaded onto the lithography machine for lithography and development. The ultraviolet radiation dose is 200 mJ / cm 2 for 10 seconds of exposure.

[0051] 5.5 It is developed using SU-8 developer until the pattern of the anode metal material is clearly and completely presented.

[0052] 5.6 After that, the stainless steel is etched using a stainless steel etching solution. The recommended component solutes of the stainless steel etching solution are FeCl3 800 g / L, HCl 100 mL / L, HF 100 mL / L, H3PO4 8 g / L, CuSO4 20 g / L; the etching depth is the thickness of the stainless steel.

[0053] 5.7 After sufficient etching, first, the surface of the silicon-316L stainless steel is thoroughly cleaned with ultrapure water; then, the SPM cleaning technology is used to strip and clean the photoresist.

[0054] (2) Preparation of the metal cathode 4

[0055] 5.8 Refer to Figure 2 , repeat step 5.4, except that a mask plate of the cathode metal material is loaded onto the lithography machine for lithography and development;

[0056] 5.9 Repeat step 5.5, except that the pattern of the cathode metal material is clearly and completely presented;

[0057] 5.10 The cathode electrode required for the electrochemical measurement of material corrosion is formed by magnetron sputtering. In this embodiment, a Cu target with 99.999% metal is selected, the working pressure is 0.5 Pa, the target voltage is 450 V, and the target current density is 20 mA / cm 2 , and the deposition rate is about 1.5 nm / min;

[0058] 5.11 The SPM cleaning technology is used to strip the photoresist on the anode and cathode metals and clean the residual metals.

[0059] The distance between the metal anode and the metal cathode is 50 μm.

[0060] (3) Preparation of the cavity structure

[0061] 5.12 Refer to Figure 3 , select a 4-inch (φ100.84 mm) glass sheet 5 as the cavity structure material, and clean the surface with deionized water; subsequently, use a cleaning solution composed of 25% hydrogen peroxide, 25% ammonia water and pure water in a volume ratio of 1:1:20 to clean the glass sheet, and the cleaning time is about 260 s; then use a cleaning solution composed of 30% hydrochloric acid, 25% hydrogen peroxide and pure water in a volume ratio of 1:1:20 to continue cleaning for 250 s; then rinse the silicon wafer with a large amount of deionized water and dry the silicon wafer with a high-speed spin-drying device, and the spin-drying process time is 300 s;

[0062] 5.13 Repeat step 5.4, except that the mask plate of the cavity structure is loaded onto the lithography machine for lithography and development;

[0063] 5.14 Repeat step 5.5, except that the pattern of the cavity structure is presented clearly and completely;

[0064] 5.15 Etch the glass sheet by deep silicon etching to remove the exposed substrate area and etch out a cavity downward in the exposed substrate area;

[0065] 5.16 Use the SPM cleaning technology to strip and clean the photoresist;

[0066] 5.17 Repeat the glass sheet cleaning process in step 5.12;

[0067] 5.18 Repeat step 5.4, except that the photoresist is coated on the back side of the glass sheet and the mask plate of the cavity structure is loaded onto the lithography machine for lithography and development;

[0068] 5.19 Repeat steps 5.15 - 5.17, except that a through hole 6 is etched from the back side of the glass sheet so that atmospheric environmental factors can pass through the glass sheet and enter the sensor surface.

[0069] (4) Silicon-glass anodic bonding

[0070] 5.20 First, use wet chemical treatment methods to chemically clean and activate the silicon-316L stainless steel sensor structure and the cavity structure. The wet chemical treatment solution is RCA1 (NH4OH:H2O2:H2O = 1:1:5) solution to clean the silicon wafer and remove organic contamination on the silicon surface; use RCA2 (HCI:H2O2:H2O = 1:1:6) solution for surface activation to treat silicon interface ions and metal contamination and increase the electrostatic tension at the silicon-glass interface;

[0071] 5.21 Connect the silicon wafer 2 to the positive pole of the power supply and the glass wafer 5 to the negative pole of the power supply. Heat up to 300 - 500 °C and apply a bias voltage of more than 500 V, so that the silicon wafer 2 and the glass wafer 5 complete bonding relying on the generated electrostatic force.

[0072] The obtained MEMS sensor is as shown in Figure 4 and Figure 5 and Figure 6 shown.

[0073] In other embodiments, the anode and cathode modules and the cavity structure module can also be connected by coating a titanium bonding layer on the surface of the cavity structure or setting solder.

[0074] This embodiment also provides a material atmospheric corrosion detection device, and the specific preparation method is as follows:

[0075] (5) Wire bonding

[0076] 5.22 Perform wire bonding on the above-obtained MEMS sensor and the nickel-palladium-silver-gold frame. Before bonding, perform plasma cleaning on the lead frame and the MEMS corrosion sensor through a plasma cleaning device. The cleaning process is: introduce argon gas into the copper of the device, place the sample in the plasma area, control the pressure at 200 Pa, and the power density is 8 W / cm 2 , and the cleaning time is 10 minutes. Subsequently, use copper bonding technology to perform wire bonding on the MEMS chip and the nickel-palladium-silver-gold frame.

[0077] In addition, the material atmospheric corrosion detection device also includes a signal processing module. The signal processing module is a dedicated ASIC chip with the ability to detect microcurrents and microvoltages. In this example, the MAX4080SASA+T current high-precision detection amplifier IC chip is selected to detect the current and voltage signals generated when the material atmospheric corrosion sensitive element is corroded by the atmosphere and convert them into material corrosion rate electrical signals. This ASIC chip is carried on the above nickel-palladium-silver-gold frame and is electrically connected to the MEMS corrosion sensor.

[0078] Finally, the MEMS material corrosion sensor and the ASIC signal processing module are encapsulated with a plastic packaging material.

[0079] This application provides a silicon-metal composite MEMS material atmospheric corrosion sensor and its preparation method. By etching out an anode electrode made of a metal material that is consistent with the structural material and combining it with a cathode electrode prepared by sputtering, a MEMS corrosion sensor with a planar structure is formed. Combining with an ASIC micro-current processing chip, the detection of the atmospheric corrosion of the metal material and the tiny corrosion current formed between the anode and the cathode is realized. Through the ASIC amplifier circuit and analog-to-digital conversion, the detection of the corrosion signal is realized. Thus, the sensor preparation technology for materials that is consistent with the structural composition and microstructure of bulk metal is achieved, eliminating the problem of inconsistent material microstructure caused by sputtering metal, which leads to a difference in the actual corrosion mechanism and the corrosion mechanism of the metal to be measured. At the same time, this application realizes the mass production of microsensors through MEMS technology, which greatly improves the consistency and linearity of the material corrosion sensor.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, not to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A silicon-metal composite MEMS material atmospheric corrosion sensor, characterized in that, It includes a cathode and anode module and a cavity structure module; The cathode and anode module includes a first substrate, and a separate metal anode and metal cathode disposed on the surface of the first substrate; The cavity structure module includes a second substrate, the second substrate is provided with a recess and a through hole for communicating with the test environment atmosphere, the recess extends from a first side of the second substrate to an opposite second side, and the through hole extends from the surface of the second side to the bottom of the recess; The surface of the second side abuts against the surface of the first substrate, and the metal cathode and the metal anode are disposed in the recess; The material of the metal anode is the metal material to be tested, and the material of the metal cathode is coupled with the metal material to be tested; The distance between the metal anode and the metal cathode is 10 - 100 μm.

2. The silicon-metal composite MEMS material atmospheric corrosion sensor according to claim 1, characterized in that The first substrate and the second substrate are each independently a silicon wafer or glass.

3. The silicon-metal composite MEMS material atmospheric corrosion sensor according to claim 1 or 2, characterized in that, The first substrate is a silicon wafer, the second substrate is glass, the metal material to be tested is stainless steel, and the material of the metal cathode is copper.

4. A method for preparing a silicon-metal composite MEMS material atmospheric corrosion sensor according to any one of claims 1-3, characterized in that, It includes: Bonding the sheet-shaped metal material to be tested with the first substrate to obtain a substrate-metal composite sheet; Applying a photoresist on the surface of the substrate-metal composite sheet, then using a mask plate with a metal anode pattern for exposure, development, and fixing to form a metal anode target pattern; Etching using the metal anode target pattern until the first substrate is exposed, and then removing the residual photoresist to obtain a first composite sheet; Applying a photoresist on the side of the first composite sheet having the metal anode, using a mask plate with a metal cathode pattern for exposure, development, and fixing to form a metal cathode target pattern to obtain a second composite sheet; adopting a sputtering method, sputtering a cathode material on the second composite sheet, and then removing the residual photoresist and residual cathode material on the second composite sheet to obtain the cathode and anode module; Applying a photoresist on the first side of the second substrate, then using a mask plate with a pattern of the recess for exposure, development, and fixing to form a recess target pattern; Etching using the recess target pattern until the recess is formed; Removing the residual photoresist, then applying a photoresist on the second side, and then using a mask plate with a pattern of the through hole for exposure, development, and fixing to form a through hole target pattern; Etching using the through hole target pattern until the through hole is formed, and removing the residual photoresist to obtain the cavity structure module; Placing the metal anode and the metal cathode of the cathode and anode module in the recess of the cavity structure module, and then connecting the surface of the second side of the first substrate to the surface of the first substrate.

5. The preparation method of the silicon-metal composite MEMS material atmospheric corrosion sensor according to claim 4, characterized in that, The bonding is carried out using a two-component polydimethylsiloxane adhesive.

6. The preparation method of the silicon-metal composite MEMS material atmospheric corrosion sensor according to claim 4, characterized in that, When etching using the metal anode target pattern, the etchant includes: HCl 2.7 - 5.4 mol / L, hydrogen peroxide 4.4 - 7.4 mol / L, corrosion inhibitor 1 - 10 g / L, dispersant 20 - 50 g / L, hydrogen peroxide stabilizer 5 - 10 g / L.

7. The preparation method of the silicon-metal composite MEMS material atmospheric corrosion sensor according to any one of claims 4-6, characterized in that The connection includes: The surfaces of the second side and the first substrate are chemically cleaned and activated by a wet chemical treatment method; The first substrate is connected to the positive electrode of the power supply, and the second substrate is connected to the negative electrode of the power supply. The temperature is raised to 300 - 500 °C, and a bias voltage of more than 500 V is applied to bond the first substrate and the second substrate by the generated electrostatic force.

8. An atmospheric corrosion detection device for materials, characterized in that, It includes the silicon-metal composite MEMS material atmospheric corrosion sensor according to any one of claims 1 - 3.

9. The material atmospheric corrosion detection device according to claim 8, characterized in that, It further includes a signal processing module electrically connected to the silicon-metal composite MEMS material atmospheric corrosion sensor, and the signal processing module includes an ASIC chip with the ability to detect microcurrent and microvoltage.

10. The material atmospheric corrosion detection device according to claim 9, characterized in that, It further includes a lead frame structure capable of carrying the silicon-metal composite MEMS material atmospheric corrosion sensor and the ASIC chip.

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