A method generally applicable to the preparation of a CMAR based on a PDMS diaphragm

Abstract

The application provides a method for preparing a CMAR based on a PDMS vibrating diaphragm, and belongs to the technical fields of micro-electro-mechanical system processing, flexible polymer film transfer, micro-acoustic sensor manufacturing and implantable acoustic device preparation. The application adopts a route of surface activation + low-temperature hot pressing to prepare the PDMS vibrating diaphragm CMAR. The core is not to perform wafer bonding on two rigid wafers, but to use a flexible PDMS film as a transferable functional layer to perform hot pressing on a substrate with a cavity at a lower temperature. The application enables the device to be sealed and assembled with the flexible vibrating diaphragm and the substrate with the cavity only through low-temperature and short-time hot pressing without relying on a complex sacrificial layer release and fine wafer bonding, and is compatible with array manufacturing. The application realizes that the sealing and pressing can be completed through 100-degree hot pressing for 15 minutes, so that the manufacturability of the flexible vibrating diaphragm CMAR is significantly improved.

Description

Technical Field

[0001] This invention proposes a method universally applicable to the fabrication of capacitive micromechanical acoustic receivers (CMARs) based on polydimethylsiloxane (PDMS) diaphragms, belonging to the technical fields of microelectromechanical systems (MEMS) fabrication, flexible polymer film transfer, microacoustic sensor manufacturing, and implantable acoustic device fabrication. Background Technology

[0002] Existing capacitive micromechanical ultrasonic transducers (CMUTs) typically rely on wafer-level bonding or sacrificial layer release to form a sealed cavity. Wafer bonding processes have high requirements for surface flatness, temperature, bonding equipment, alignment accuracy, and material matching. Sacrificial layer release, especially when the diaphragm to be packaged is a flexible polymer film such as polydimethylsiloxane (PDMS), is difficult to implement, has a narrow process window, and is costly, which is not conducive to rapid iteration and universal fabrication.

[0003] Currently, the most commonly used wafer bonding process in the fabrication of silicon-based CMUTs is direct silicon / silicon dioxide bonding. Regarding bonding surface conditions, literature generally emphasizes that direct bonding requires very high surface flatness and cleanliness. The bonding surface typically needs to be cleaned with a piranha solution and surface activated, and the surface micro-roughness should generally be below approximately 0.5 nm to achieve reliable bonding. This requirement can usually be met by wafer cleaning and chemical mechanical polishing. In the direct bonding CMUT process, after the two wafers come into contact in a vacuum, they are immediately annealed in a high-vacuum environment at approximately 1100 degrees Celsius, while simultaneously being subjected to a 3 kg / cm² pressure. 2 The force is used to form strong covalent bonds.

[0004] In existing technologies, a cavity is typically formed on a silicon substrate first through photolithography and etching, then an insulating layer and a lower electrode are deposited, and finally bonded to it using another functional wafer or film carrier to form a closed cavity. This approach originates from the traditional CMUT manufacturing process, which, although mature, suffers from a mismatch between bonding requirements and process supply when combined with flexible polymer diaphragms.

[0005] The main drawbacks of existing preparation processes include: 1. Direct bonding equipment has high requirements and high manufacturing costs; 2. High-temperature or high-stress bonding is detrimental to the dimensional stability and yield control of PDMS flexible films; 3. The direct bonding window between the flexible film layer and the rigid substrate is narrow, which can easily lead to material deformation, wrinkling, voids or uneven sealing. Summary of the Invention

[0006] The technical problem to be solved by this invention is to provide a method that is universally applicable to the fabrication of capacitive micromechanical acoustic receivers (CMARs) based on polydimethylsiloxane (PDMS) diaphragms. This method enables the device to achieve sealed assembly of the flexible diaphragm and cavity substrate through only low-temperature and short-time hot-press bonding without relying on complex sacrificial layer release and fine wafer bonding, and is compatible with array manufacturing.

[0007] The purpose of this invention is to provide a PDMS diaphragm CMAR preparation method with clear steps, a wide parameter window, and low equipment dependence, focusing on achieving "bonding and sealing can be completed by hot pressing at 100 degrees Celsius for 15 minutes", thereby significantly improving the manufacturability of flexible diaphragm CMAR.

[0008] This invention employs a "surface activation + low-temperature hot-press bonding" approach to prepare PDMS diaphragm CMARs. The core technology no longer involves wafer bonding of two rigid wafers, but rather uses a flexible PDMS film as a transferable functional layer, which is hot-pressed onto a cavity substrate at a lower temperature.

[0009] The method steps for preparing the CMAR chip according to the present invention are described in detail below: Step 1. Provide a silicon substrate, preferably <100> Silicon wafers. The silicon substrate undergoes sequential organic cleaning, deionized water rinsing, and dehydration treatment to meet the requirements of subsequent photolithography and etching.

[0010] Step 2. Spin coat a positive photoresist onto the silicon substrate surface, preferably at a speed of about 3000 rpm, and pre-bake at about 120 degrees Celsius for about 2 minutes.

[0011] Step 3. Subsequently, the cavity and lower electrode pad area are defined using a mask or direct write exposure method, followed by development.

[0012] Step 4. Perform deep reactive ion etching (DRIE) on the exposed silicon areas, preferably using the Bosch deep reactive ion etching process, to form a depth of 10μm–50μm. Remove residual photoresist after etching.

[0013] Step 5. Deposit an insulating layer on the etched silicon substrate surface, preferably silicon dioxide deposited by plasma-enhanced chemical vapor deposition (PECVD), with a thickness of 100nm–1000nm. This insulating layer is used to isolate the electrodes and improve device reliability. Simultaneously, the lower electrode pad area is covered by a mask, which can be made of silicon, metal, or other materials. This mask can be prepared or custom-purchased, is reusable, and is only used to cover the lower electrode pad area.

[0014] Step 6. After the silicon dioxide deposition is completed by PECVD, remove the mask from step 5. Since the mask is relatively large, it can be removed directly.

[0015] Step 7. Form the lower electrode pad in the predetermined area using a mask. Preferably, a metal layer is deposited using sputtering, evaporation, and / or patterning processes as the lower electrode pad portion. The metal thickness can be 50nm–300nm; the metal material can be Au, Cr and Au, Ti and Au, Pt, or other conductive metals. The mask can be silicon-based, metal, or other materials. This mask can be prepared or custom-purchased, and can be reused to mask areas other than the lower electrode pad.

[0016] Step 8. After completing the metal layer deposition at the lower electrode pad, remove the mask from step 7. Since the mask is relatively large, it can be removed directly. After completing this step, the cavity substrate is obtained.

[0017] Step 9. Provide a temporary carrier substrate, which may be a silicon wafer, a glass sheet, or a flat substrate with a release layer on its surface. The carrier substrate is then subjected to organic cleaning, deionized water rinsing, and dehydration treatment in sequence to meet the requirements of subsequent thin film deposition.

[0018] Step 10. Prepare a PDMS film on the carrier substrate to obtain a temporary carrier substrate and PDMS composite layer, or prepare a release layer and PDMS film on the carrier substrate, referred to as the composite layer. The release layer can be a water-soluble polyvinyl alcohol thin layer or other materials that can be selectively removed by wet etching or are easily soluble in water. PDMS is preferably a commercial two-component system of Dow Corning / Dow PDMS (Sylgard 184). The base adhesive and curing agent are mixed at a mass ratio of 10:1, degassed, and then spin-coated onto the surface of the carrier substrate. The PDMS film thickness is adjusted to 5μm–30μm by adjusting the rotation speed, time, and viscosity. Pre-curing or complete curing is then performed to give the PDMS film transferable mechanical integrity. This composite layer and the cavity substrate obtained in Step 8 are activated with oxygen plasma. This involves etching the surfaces of the PDMS and cavity substrate with oxygen plasma at low power in a vacuum environment. After the composite layer and cavity substrate are ignited, they are roughly aligned so that the composite layer of the same area completely covers the cavity substrate area.

[0019] Step 11. After rough alignment, the composite layer and the cavity substrate from Step 8 are hot-pressed together in a hot press. Preferred conditions are: a temperature of approximately 100 degrees Celsius, a holding time of approximately 15 minutes, and a pressure between 0.01 MPa and 0.2 MPa applied to achieve a surface-to-surface seal. This step is crucial to the invention, as it completes the cavity encapsulation through the bonding between the composite layer and the cavity substrate, eliminating the need for traditional wafer bonding.

[0020] Step 12. After hot pressing and cooling to room temperature, the temporary carrier substrate and PDMS in the composite layer are removed by dry etching. The release layer in the composite layer, along with the PDMS, is removed by wet etching, causing the temporary carrier substrate to detach. After removing the temporary carrier substrate, the PDMS diaphragm remains in a sealed and suspended state on the cavity substrate, forming the original CMAR.

[0021] Step 13. Deposit the top electrode for the original CMAR. Preferably, an indium tin oxide (ITO) thin layer is formed by sputtering under the influence of a mask. Alternatively, Au, Pt, Cr / Au, graphene, silver nanowires, or conductive polymer thin layers can be used. The thickness of the top electrode is preferably 20 nm–100 nm. This mask can be prepared or custom-purchased, and can be reused to cover an area slightly larger than the bottom electrode pad.

[0022] Step 14. After completing the deposition of the top metal layer, remove the mask from step 13. Since the mask is large, it can be removed directly.

[0023] Step 15. Further complete the cutting, wire connection, printed circuit board (PCB) packaging and testing as needed to obtain the CMAR chip or array device based on the PDMS diaphragm.

[0024] In the above methods, the carrier substrate can be silicon, glass, metal plate, or polymer plate with release coating; In the above methods, the PDMS film formation method can be spin coating, blade coating, casting, molding, or pre-film transfer; In the above method, the hot pressing temperature can be adjusted within the range of 80 degrees Celsius to 200 degrees Celsius, and the time can be adjusted within the range of 5 minutes to 30 minutes, as long as a reliable fit can be formed; In the above methods, the insulating layer and electrode materials can be replaced according to the application scenario. The choice depends on factors such as the rigidity or flexibility of the device, whether the material needs to transmit electromagnetic waves of a specific wavelength, whether the device is used in vivo or in vitro, the biocompatibility of the material, the required dielectric constant of the material, the required breakdown voltage of the material, the market price of the material, and the packaging requirements of the device. In the above methods, the temporary carrier substrate can be removed by mechanical peeling, or by wet or dry methods to remove the intermediate release layer.

[0025] The above method is not strictly limited to specific materials. As long as the core process logic of "lower cavity structure + carrier-assisted PDMS film formation + low-temperature hot-press bonding to form a closed cavity" is met, it falls within the protection scope of this invention. This method can be used for a single CMAR cell or for an array CMAR.

[0026] The innovation of this invention lies in: 1. A flexible PDMS film is pre-prepared on a temporary carrier and then bonded to a cavity substrate; 2. After activation by oxygen plasma, a low-temperature short-time process of hot pressing at 100 degrees Celsius for 15 minutes is used to complete the sealing, instead of using traditional wafer bonding; 3. The PDMS film, upper electrode, and lower cavity structure are fabricated in a decoupled manner to improve process compatibility; 4. A free PDMS diaphragm across the cavity is formed through carrier assistance and subsequent carrier removal steps; 5. This method is applicable to both single devices and array devices, and has universality and scalability.

[0027] The advantages and beneficial effects of this invention are as follows: 1. Compared with traditional wafer bonding, the present invention does not rely on strict dual-wafer bonding conditions, the process is simpler, the equipment requirements are lower, and the cost is more controllable.

[0028] 2. Compared with processes for rigid films, the present invention is more suitable for flexible polymer films such as PDMS, and can reduce film damage, wrinkling and stress mismatch problems.

[0029] 3. This invention is particularly suitable for rapid iteration and small-batch trial production in the R&D stage, while retaining the possibility of expansion to array-based and large-scale manufacturing.

[0030] 4. Compared with traditional wafer bonding, this invention is more suitable for laboratory and pilot line environments, and can significantly reduce the development threshold of flexible CMAR. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the method of the present invention.

[0032] Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0033] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The following are different embodiments to illustrate the practicality and scope of application of the present invention, but the present invention is not limited to the following specific parameters.

[0035] Figure 1The fabrication process of a CMAR device based on a PDMS diaphragm is shown in the figure, with the fabrication sequence proceeding sequentially according to numbers (1) to (15) in the figure. First, a silicon substrate is provided, and photoresist is formed on the surface of the silicon substrate. Then, the cavity and pad / lead areas are formed in the silicon substrate through two photolithography and etching processes, and a silicon dioxide insulating layer is deposited on the corresponding surface. Next, the lower electrode structure is formed by mask patterning and metal deposition. On the other hand, a PDMS thin film is fabricated on a temporary carrier substrate, and the PDMS thin film is aligned and bonded to the silicon substrate with the fabricated cavity and electrode, so that the PDMS thin film covers the cavity area and forms a diaphragm structure. After removing the temporary carrier, a metal upper electrode is deposited on the PDMS diaphragm. Finally, the fabricated CMAR is connected to a PCB and packaged to obtain a PDMS diaphragm CMAR chip that can be used for acoustic signal detection.

[0036] Example 1: Fabrication of single or multiple circular CMAR units Step 1. Select a 4-inch screen. <100> The silicon wafer, as the silicon substrate, is sequentially cleaned with acetone, isopropanol, and deionized water, and then dehydrated and baked at 120 degrees Celsius for 5 minutes to meet the requirements of subsequent photolithography and etching.

[0037] Step 2. Spin coat the positive photoresist Shipley 1811 onto the silicon substrate at 3000 rpm for 30 seconds, and pre-bake at 120 degrees Celsius for 2 minutes.

[0038] Step 3. Subsequently, the cavity and lower electrode pad area are defined using the direct write exposure method (equipment model: MLA150 Direct Write UVLithography system). After exposure, the cavity and pad area are immersed in developer (model: MF-319) for 45 seconds to form a circular cavity pattern and pad area pattern with a radius of about 150μm.

[0039] Step 4. Use the DRIE Bosch cyclic etching process to etch the exposed silicon area to a depth of approximately 15 μm. After etching, clean the area sequentially with acetone, isopropanol, and deionized water, and then bake at 120 degrees Celsius for 5 minutes to remove residual photoresist.

[0040] Step 5. Deposit an insulating layer on the etched silicon substrate surface by plasma-enhanced chemical vapor deposition (PECVD) to deposit a 500 nm silicon dioxide film. Simultaneously, the lower electrode pad area is covered by a mask made of silicon wafer. This mask is pre-prepared, reusable, and only used to mask the lower electrode pad area.

[0041] Step 6. After the silicon dioxide deposition is completed by PECVD, remove the mask from step 5. Since the mask is relatively large, it can be removed directly.

[0042] Step 7. Subsequently, with an acrylic mask overlaid, 10 nm of Cr and 90 nm of Au are deposited on the predetermined area by metal sputtering to form the lower electrode pad, with a total metal thickness of approximately 100 nm. This mask is made of acrylic material, is prepared in advance, and can be reused multiple times to mask areas other than the lower electrode pad.

[0043] Step 8. After completing the metal layer deposition at the lower electrode pad, remove the acrylic mask from Step 7. Since the mask is relatively large, it can be removed directly. After completing this step, the cavity substrate is obtained.

[0044] Step 9. Prepare a silicon wafer as a temporary substrate. The temporary substrate is subjected to organic cleaning, deionized water rinsing, and dehydration treatment in sequence to meet the requirements of subsequent thin film deposition.

[0045] Step 10. Spin-coat Sylgard 184 PDMS onto the cleaned temporary carrier substrate. The base adhesive to curing agent mass ratio is 10:1. After degassing, spin-coat to form a PDMS film approximately 10 μm thick. Cure at 80°C for 30 minutes to obtain a composite layer consisting of the temporary carrier substrate and PDMS. After activating this composite layer with the cavity substrate obtained in Step 8 using oxygen plasma for 60 seconds, the composite layer and cavity substrate are cremated and roughly aligned to ensure that the composite layer of the same area completely covers the cavity substrate area.

[0046] Step 11. After rough alignment, the composite layer and the cavity substrate are hot-pressed together in a hot press at 100 degrees Celsius for approximately 15 minutes, and a pressure of 0.2 MPa is applied to achieve a surface-to-surface seal. This step is crucial to the invention, as it enables cavity encapsulation through the bonding between the composite layer and the cavity substrate, eliminating the need for traditional wafer bonding.

[0047] Step 12. After hot pressing and cooling to room temperature, the temporary carrier substrate in the composite layer is removed by dry etching. After removing the temporary carrier substrate, the PDMS diaphragm remains in a sealed cavity substrate and suspended state on the cavity substrate to form the original CMAR.

[0048] Step 13. For the original CMAR, deposit the top electrode by sputtering a 50 nm indium tin oxide (ITO) thin layer using polyimide as a mask. This is purchased and used to mask an area slightly larger than the lower electrode pad.

[0049] Step 14. After completing the deposition of the top metal layer, remove the mask from step 13. Since the mask is large, it can be removed directly.

[0050] Step 15. Secure the device with the top metallized layer onto a printed circuit board (PCB) and connect the top and bottom electrode pads to the positive and negative pads on the PCB using leads, thereby obtaining a CMAR chip or array device based on a PDMS diaphragm. PCBs can be customized or purchased. Example 2: Preparation of low-damage transfer using a release layer carrier Step 1. Select a 4-inch screen. <100> The silicon wafer, as the silicon substrate, is sequentially cleaned with acetone, isopropanol, and deionized water, and then dehydrated and baked at 120 degrees Celsius for 5 minutes to meet the requirements of subsequent photolithography and etching.

[0051] Step 2. Spin coat the positive photoresist Shipley 1811 onto the silicon substrate at 3000 rpm for 30 seconds, and pre-bake at 120 degrees Celsius for 2 minutes.

[0052] Step 3. Subsequently, the cavity and lower electrode pad area are defined using the direct write exposure method (equipment model: MLA150 Direct Write UVLithography system). After exposure, the cavity and pad area are immersed in developer (model: MF-319) for 45 seconds to form a circular cavity pattern and pad area pattern with a radius of about 150μm.

[0053] Step 4. Use the DRIE Bosch cyclic etching process to etch the exposed silicon area to a depth of approximately 15 μm. After etching, clean the area sequentially with acetone, isopropanol, and deionized water, and then bake at 120 degrees Celsius for 5 minutes to remove residual photoresist.

[0054] Step 5. Deposit an insulating layer on the etched silicon substrate surface by plasma-enhanced chemical vapor deposition (PECVD) to deposit a 500 nm silicon dioxide film. Simultaneously, the lower electrode pad area is covered by a mask made of silicon wafer. This mask is pre-prepared, reusable, and only used to mask the lower electrode pad area.

[0055] Step 6. After the silicon dioxide deposition is completed by PECVD, remove the mask from step 5. Since the mask is relatively large, it can be removed directly.

[0056] Step 7. Subsequently, with an acrylic mask overlaid, 10 nm of Cr and 90 nm of Au are deposited on the predetermined area by metal sputtering to form the lower electrode pad, with a total metal thickness of approximately 100 nm. This mask is made of acrylic material, is prepared in advance, and can be reused multiple times to mask areas other than the lower electrode pad.

[0057] Step 8. After completing the metal layer deposition at the lower electrode pad, remove the acrylic mask from Step 7. Since the mask is relatively large, it can be removed directly. After completing this step, the cavity substrate is obtained.

[0058] Step 9. Prepare a silicon wafer as a temporary substrate. The temporary substrate is subjected to organic cleaning, deionized water rinsing, and dehydration treatment in sequence to meet the requirements of subsequent thin film deposition.

[0059] Step 10. Spin-coat polyvinyl alcohol onto the cleaned temporary carrier substrate and dry it, then spin-coat Sylgard 184 type PDMS with a base adhesive to curing agent mass ratio of 10:1. After degassing, spin-coat to form a PDMS film approximately 10 μm thick, and cure at 80 degrees Celsius for 30 minutes to obtain a composite layer consisting of a temporary carrier substrate, polyvinyl alcohol, and PDMS. After activating this composite layer with the cavity substrate obtained in Step 8 using oxygen plasma for 60 seconds, the composite layer and the cavity substrate are cremated and roughly aligned to ensure that the composite layer of the same area completely covers the cavity substrate area.

[0060] Step 11. After rough alignment, the composite layer and the cavity substrate are hot-pressed together in a hot press at 100 degrees Celsius for approximately 15 minutes, and a pressure of 0.2 MPa is applied to achieve a surface-to-surface seal. This step is crucial to the invention, as it enables cavity encapsulation through the bonding between the composite layer and the cavity substrate, eliminating the need for traditional wafer bonding.

[0061] Step 12. After hot pressing and cooling to room temperature, the polyvinyl alcohol in the composite layer is removed by wet etching, thereby causing the temporary carrier substrate to detach. After removing the temporary carrier substrate, the PDMS diaphragm remains in a sealed and suspended state on the cavity substrate, forming the original CMAR. This method reduces the risk of stretching and tearing of the thin PDMS diaphragm during mechanical peeling, and is particularly suitable for CMAR devices with thin film thickness, large array area, or fragile upper electrode layer.

[0062] Step 13. For the original CMAR, deposit the top electrode by sputtering a 50 nm indium tin oxide (ITO) thin layer using polyimide as a mask. This is purchased and used to mask an area slightly larger than the lower electrode pad.

[0063] Step 14. After completing the deposition of the top metal layer, remove the mask from step 13. Since the mask is large, it can be removed directly.

[0064] Step 15. Secure the device with the top metallized layer onto a printed circuit board (PCB) and connect the top and bottom electrode pads to the positive and negative pads on the PCB using leads, thereby obtaining a CMAR chip or array device based on a PDMS diaphragm. PCBs can be customized or purchased. As can be seen from the above two embodiments, the present invention is applicable to single CMAR units, arrayed CMAR chips, and PDMS diaphragm transfer processes using different carrier removal methods, and can form a reliable cross-cavity PDMS diaphragm structure under low temperature and short-time hot pressing conditions.

Claims

1. A method universally applicable to the fabrication of CMARs based on PDMS diaphragms, characterized in that, Includes the following steps: Step 1. Provide a silicon substrate and perform organic cleaning, deionized water rinsing and dehydration treatment on the silicon substrate in sequence to meet the requirements of subsequent photolithography and etching; Step 2. Spin-coat positive photoresist onto the silicon substrate at 3000 rpm and pre-bake at 120 degrees Celsius for 2 minutes; Step 3. Define the cavity and lower electrode pad area using a mask or direct-write exposure method, then develop the product; Step 4. Perform deep reactive ion etching (DRIE) on the exposed silicon area, and remove the residual photoresist after etching is complete; Step 5. Deposit an insulating layer on the etched silicon substrate surface. This insulating layer is used to isolate the electrodes and improve device reliability. At the same time, the lower electrode pad area is covered by a mask, which is only used to block the lower electrode pad area. Step 6. After the PECVD deposition of silicon dioxide is completed, remove the mask from step 5; Step 7. Form a lower electrode pad in a predetermined area using a mask; deposit a metal layer as the lower electrode pad portion using sputtering, evaporation and / or patterning processes, and use a mask to cover the area other than the lower electrode pad. Step 8. After completing the metal layer deposition at the lower electrode pad, the cavity substrate is obtained; Step 9. Provide a temporary carrier substrate, and perform organic cleaning, deionized water rinsing and dehydration treatment on the carrier substrate in sequence to meet the requirements of subsequent thin film deposition; Step 10. Prepare a PDMS thin film on a carrier substrate to obtain a temporary carrier substrate and PDMS composite layer, or prepare a release layer and PDMS composite layer on a carrier substrate; activate the composite layer and the cavity substrate obtained in step 8 with oxygen plasma, and etch the surfaces of PDMS and cavity substrate with low power oxygen plasma in a vacuum environment; after the composite layer and cavity substrate are ignited, perform rough alignment so that the composite layer of the same area completely covers the cavity substrate area; Step 11. After rough alignment, the composite layer and the cavity substrate from step 8 will be hot-pressed together in a hot press; the cavity encapsulation is completed by bonding the composite layer and the cavity substrate, without the need for traditional wafer bonding. Step 12. After hot pressing and cooling to room temperature, for the composite layer of temporary carrier substrate and PDMS, the temporary carrier substrate in the composite layer is removed by dry etching; for the composite layer of temporary carrier substrate, release layer and PDMS, the release layer in the composite layer is removed by wet etching, thereby causing the temporary carrier substrate to detach; after the temporary carrier substrate is removed, the PDMS diaphragm will remain in a sealed cavity substrate and suspended state on the cavity substrate to form the original CMAR; Step 13. For the original CMAR deposition of the top electrode, under the action of the mask, an indium tin oxide (ITO) thin layer is formed by sputtering. The thickness of the top electrode is 20nm–100nm; the mask is used to cover the area slightly larger than the bottom electrode pad. Step 14. After completing the deposition of the top metal layer, remove the mask from step 13; Step 15. Further complete the cutting, wire connection, printed circuit board packaging and testing as needed to obtain the CMAR chip or array device based on the PDMS diaphragm.

2. The method for preparing a CMAR based on a PDMS diaphragm according to claim 1, characterized in that: In step 4, Bosch deep reactive ion etching process is used to form a depth of 10μm–50μm.

3. The method for preparing a CMAR based on a PDMS diaphragm according to claim 1, characterized in that: In step 5, silicon dioxide deposited by plasma-enhanced chemical vapor deposition (PECVD) with a thickness of 100 nm–1000 nm is selected.

4. The method for preparing a CMAR based on a PDMS diaphragm according to claim 1, characterized in that: In step 7, the metal thickness is 50nm–300nm; the metal material is Au, Cr and Au, Ti and Au, Pt.

5. The method for preparing a CMAR based on a PDMS diaphragm according to claim 1, characterized in that: In step 10, the release layer is a water-soluble thin film of polyvinyl alcohol or other materials that can be selectively removed by wet etching or are easily soluble in water; the PDMS uses the commercial two-component system Sylgard184 of Dow Corning / Dow PDMS. The base adhesive and curing agent are mixed at a mass ratio of 10:1, degassed, and then spin-coated onto the surface of the carrier substrate. The thickness of the PDMS film is made up of 5μm–30μm by adjusting the rotation speed, time, and viscosity. The PDMS film is then pre-cured or fully cured to give it transferable mechanical integrity.

6. The method for preparing a CMAR based on a PDMS diaphragm according to claim 1, characterized in that: In step 13, Au, Pt, Cr / Au, graphene, silver nanowires, or conductive polymer thin layers may be used.

7. The method for preparing a CMAR based on a PDMS diaphragm according to claim 1, characterized in that: In step 9, step 10 or step 12, the carrier substrate is silicon, glass, metal plate or polymer plate with release coating.

8. The method for preparing a CMAR based on a PDMS diaphragm according to claim 1, characterized in that: In step 11, the hot pressing temperature is 80 degrees Celsius–200 degrees Celsius, the time is 5 minutes–30 minutes, and the pressure applied to achieve a surface contact seal is between 0.01 MPa and 0.2 MPa, thus forming a reliable fit.

9. A method for preparing CMARs based on PDMS diaphragms according to claim 1, characterized in that: PDMS film formation methods include spin coating, blade coating, casting, molding, or pre-film transfer.

10. A method for preparing a CMAR based on a PDMS diaphragm according to any one of claims 1-9, characterized in that: The specific materials are not strictly limited; as long as they meet the requirements of "lower cavity structure + carrier-assisted PDMS film formation + low-temperature hot pressing to form a closed cavity", they can be used for a single CMAR unit or for an array CMAR.

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