Pendent cantilever structure, preparation method thereof and application of pendent cantilever structure in MEMS (Micro Electro Mechanical System) biosensor

Abstract

The invention discloses a pendent cantilever structure, a preparation method thereof and an application of the pendent cantilever structure in an MEMS (micro-electromechanical system) biosensor, and relates to the technical field of MEMS sensing. The pendent cantilever structure comprises a supporting part and at least one cantilever arm, the cantilever arm is arranged to convexly extend from the supporting part to one side far away from the supporting part, and the preparation method comprises the following steps: providing a substrate; coating at least one polymer film layer on the top surface of the substrate; preparing and obtaining a continuous line / gap mask with a preset width; sequentially carrying out exposure treatment and development treatment on the polymer film layer by using a mask so as to prepare and obtain a drooping cantilever structure in the polymer film layer; wherein the droop depth of the droop type cantilever beam structure is increased along with the reduction of the preset width. The size range of the drooping type cantilever structure prepared by the preparation method of the drooping type cantilever structure is large, and the drooping type cantilever structure has a drooping type structure, so that the detection range and the detection sensitivity of the drooping type cantilever structure applied to the field of MEMS sensing are improved.

Description

Technical Field

[0001] The invention belongs to the field of MEMS (Micro-Electro-Mechanical System) technology, and in particular relates to a drooping cantilever beam structure and a preparation method thereof and application in a biological MEMS sensor. Background Art

[0002] MEMS refers to a micro device or system that integrates micro mechanisms, micro sensors, micro actuators, and signal processing and control circuits. It has the characteristics of small size, light weight, low power consumption, and high performance, which makes MEMS have broad application prospects in many fields. Among them, the cantilever structure is the key structure in MEMS, which is used to convert external physical stimuli (such as force, pressure, temperature, etc.) into electrical signals, that is, the cantilever structure is usually used in sensor detection and mechanical measurement.

[0003] In the prior art, cantilever beam structures usually use inorganic materials such as Si and SiO2 as the preparation materials of cantilever beam structures, and use photolithography technology and wet etching technology to prepare silicon-based cantilever beam structures with a size less than 5μm. However, the size of the cantilever beam structure prepared by the above process technology is limited, that is, the size of the silicon-based cantilever beam structure exceeds 5μm, and due to mechanical force or heat, the device may fail or its life may be shortened. In some MEMS biological detection chips, the cantilever beam structure is required to sag, and the cantilever beam structure prepared by inorganic materials (such as Si, SiO2, etc.) cannot achieve the drooping effect and cannot meet the requirements. Summary of the invention

[0004] One object of the first aspect of the present invention is to provide a method for preparing a drooping cantilever beam structure, so as to solve the technical problem in the prior art that the inorganic material cantilever beam structure is limited in size and has a small detection range.

[0005] Another object of the first aspect of the present invention is to improve the mechanical strength of the drooping cantilever beam structure.

[0006] The second aspect of the present invention aims to provide a drooping cantilever beam structure, which is prepared according to the above-mentioned preparation method.

[0007] The third aspect of the present invention aims to provide an application of a drooping cantilever beam structure in a biological MEMS sensor, wherein the drooping cantilever beam structure is prepared according to the above-mentioned preparation method.

[0008] According to the purpose of the first aspect of the present invention, the present invention provides a method for preparing a drooping cantilever beam structure, the drooping cantilever beam structure comprising a support portion and at least one cantilever beam arm, the cantilever beam arm being arranged to protrude from the support portion toward a side away from the support portion, the preparation method comprising the following steps:

[0009] providing a substrate;

[0010] Coating at least one polymer film layer on the top surface of the substrate;

[0011] Prepare a mask having continuous lines / spaces with a preset width;

[0012] The polymer film layer is sequentially exposed and developed using the mask to prepare the drooping cantilever beam structure in the polymer film layer; wherein,

[0013] The drooping depth of the drooping cantilever beam structure increases as the preset width decreases.

[0014] Optionally, the polymer film layer is made of polymer material.

[0015] Optionally, the step of sequentially performing an exposure process and a development process on the polymer film layer using the mask to prepare the drooping cantilever beam structure in the polymer film layer further includes the following steps:

[0016] The exposure energy and exposure focus of the exposure process are adjusted to adjust the crosslinking degree and exposure depth of the polymer film layer.

[0017] Optionally, in the step of sequentially performing an exposure process and a development process on the polymer film layer using the mask to prepare the drooping cantilever beam structure in the polymer film layer, the preparation method further comprises the following steps:

[0018] After the polymer film layer is exposed, the polymer is subjected to post-exposure baking.

[0019] Optionally, in the step of sequentially performing an exposure process and a development process on the polymer film layer using the mask to prepare the drooping cantilever beam structure in the polymer film layer, the preparation method further comprises the following steps:

[0020] After the polymer film layer is developed, the polymer film layer is cured.

[0021] Optionally, in the step of coating at least one polymer film layer on the top surface of the substrate, the preparation method further comprises the following steps:

[0022] The substrate and the polymer film layer are subjected to a heating treatment.

[0023] Optionally, in the step of providing a substrate, the preparation method further comprises the following steps:

[0024] The substrate is sequentially subjected to plasma cleaning, wet cleaning and dehydration baking.

[0025] Optionally, the substrate is made of silicon wafer or glass.

[0026] According to the purpose of the second aspect of the present invention, the present invention further provides a drooping cantilever beam structure, the drooping cantilever beam structure comprising:

[0027] A support portion, located on the top surface of the substrate, and the support portion is configured to protrude upward from the top surface of the substrate toward a side away from the substrate;

[0028] At least one cantilever arm, the cantilever arm is arranged to protrude from the support portion toward a side away from the support portion; wherein,

[0029] The drooping cantilever beam structure is prepared according to any of the preparation methods described above.

[0030] According to the purpose of the third aspect of the present invention, the present invention further provides an application of a drooping cantilever beam structure in a biological MEMS sensor, wherein the drooping cantilever beam structure is prepared according to any of the preparation methods described above.

[0031] The present invention prepares a mask plate with continuous lines / gaps of preset width, and uses the mask plate to sequentially expose and develop a polymer film layer located on the top surface of a substrate to prepare a drooping cantilever beam structure with a size range of any value between 1 μm and 1000 μm. The drooping cantilever beam structure prepared in this embodiment has a larger size range, thereby improving the detection sensitivity of the drooping cantilever beam structure 100 applied to a biological MEMS sensor, and increasing the detection range of the drooping cantilever beam structure applied to a biological MEMS sensor.

[0032] Furthermore, in the present invention, after developing the polymer film layer, curing the polymer can solidify the polymer film layer, thereby improving the corrosion resistance and mechanical strength of the drooping cantilever beam structure.

[0033] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0035] Figure 1 is a schematic flow chart of a method for preparing a drooping cantilever beam structure according to an embodiment of the present invention;

[0036] Figure 2 is a schematic structural diagram of a drooping cantilever beam structure according to an embodiment of the present invention;

[0037] Figure 3 is a schematic structural diagram of a mask in a horizontal state according to an embodiment of the present invention.

[0038] Reference numerals:

[0039] 100-drooping cantilever structure, 200-substrate, 10-supporting portion, 20-cantilever arm. DETAILED DESCRIPTION

[0040] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0041] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0042] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0043] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] Figure 1 is a schematic flow chart of a method for preparing a drooping cantilever beam structure according to an embodiment of the present invention. Figure 2 is a schematic structural diagram of a drooping cantilever beam structure according to an embodiment of the present invention, Figure 3is a schematic structural diagram of a mask in a horizontal state according to an embodiment of the present invention.

[0045] like Figure 1 As shown, the present invention provides a method for preparing a drooping cantilever beam structure 100, the drooping cantilever beam structure 100 includes a support portion 10 and at least one cantilever beam arm 20, the cantilever beam arm 20 is arranged to protrude from the support portion 10 toward a side away from the support portion 10, and the preparation method includes the following steps:

[0046] Step S100: providing a substrate 200;

[0047] Step S200: coating at least one polymer film layer on the top surface of the substrate 200;

[0048] Step S300: preparing a mask having continuous lines / spaces with a preset width;

[0049] Step S400: using a mask to sequentially perform exposure processing and development processing on the polymer film layer to prepare a drooping cantilever beam structure 100 in the polymer film layer, wherein the drooping depth of the drooping cantilever beam structure 100 increases as the preset width decreases.

[0050] In this embodiment, at least one polymer film layer is first coated on the top surface of the provided substrate 200, and then a mask having a preset width and continuous lines / gaps is prepared, and the polymer film layer is sequentially exposed and developed to prepare a drooping cantilever beam structure 100. Here, the preset width of the lines / gaps of the mask is designed according to the drooping depth of the drooping cantilever beam structure 100, and the drooping depth of the drooping cantilever beam structure 100 increases as the preset width decreases, that is, the larger the preset width of the lines / gaps of the mask, the smaller the drooping depth of the drooping cantilever beam structure 100 prepared, and the smaller the preset width of the lines / gaps of the mask, the larger the drooping depth of the drooping cantilever beam structure 100 prepared. Here, the material of the polymer film layer is epoxy resin, and the thickness of the polymer film layer is 100μm.

[0051] In the present embodiment, a mask having continuous lines / gaps with a preset width is prepared, and the polymer film layer located on the top surface of the substrate 200 is sequentially exposed and developed using the mask to prepare a drooping cantilever beam structure 100 having a size range of 1 μm-1000 μm. The drooping cantilever beam structure 100 prepared in the present embodiment has a larger size range, that is, the detection range when applied to a biological MEMS sensor is increased, and can meet various size requirements of the drooping cantilever beam structure 100 and the detection range requirements of the biological MEMS sensor. The drooping cantilever beam structure 100 has a certain drooping depth, thereby improving the detection capability of the biological MEMS sensor for small changes, improving the detection sensitivity of the drooping cantilever beam structure 100 applied to the biological MEMS sensor, and increasing the detection range of the drooping cantilever beam structure applied to the biological MEMS sensor.

[0052] like Figure 3 As shown, in this embodiment, the width of the line in the mask is any value in the range of 0.5μm-2.0μm, the width of the gap is any value in the range of 0.5μm-2.0μm, and the width of the line and the width of the gap of the mask are set to be along the first horizontal direction (refer to Figure 3 The width of the mask line and the width of the gap are set to be along the second horizontal direction (refer to Figure 3 b direction) is the same as shown in the figure, so as to prepare a drooping cantilever structure 100 with a certain drooping depth, wherein the first horizontal direction is the extension direction of the cantilever arm 20, and the first horizontal direction is perpendicular to the second horizontal direction. That is, the width of the line in the mask can be 0.5μm, 0.8μm, 1.0μm, 1.5μm or 2.0μm, or any value in the range of 0.5μm-2.0μm, and the width of the gap can be 0.5μm, 0.65μm, 0.8μm, 0.9μm, 1.0μm, 1.25μm, 1.5μm, 1.75μm or 2.0μm, or any value in the range of 0.5μm-2.0μm.

[0053] In this embodiment, during the development process of the polymer film layer, PGMEA (Propylene Glycol Monomethyl Ether Acetate) is used as a developer, and the developer PGMEA is dripped on the surface of the polymer film layer to achieve the development process of the polymer film layer, or it is placed in a PGMEA developing tank to achieve the development process of the polymer film layer, wherein the development method is single-chip rotary development or tank development, and the single-chip rotary development needs to be cycled at least 15 times, and each development time is 30s. Tank development needs to be equipped with an ultrasonic system, and the development time is not less than 3min.

[0054] In a further embodiment, the material of the polymer film layer is a polymer material. In this embodiment, the polymer material can be a liquid polymer material or a dry film polymer material. Specifically, the polymer material can be a liquid material and a dry film material such as polyimide, epoxy resin, acrylic resin, etc., that is, the polymer material can be a polyimide liquid material, an epoxy resin liquid material, an acrylic resin liquid material, a polyimide dry film material, an epoxy resin dry film material or an acrylic resin dry film material. In other words, polyimide, epoxy resin and acrylic resin materials all have good biocompatibility and can be in direct contact with biological tissues or cells for the detection of biological molecules or the monitoring of biological reactions. Moreover, these liquid materials and dry film materials can be combined with MEMS manufacturing processes to achieve miniaturization and integration of biosensors.

[0055] In this embodiment, the dry film polymer material generally has high precision and stability. When preparing the drooping cantilever beam structure 100, the dry film material can ensure the size and shape accuracy of the structure, thereby improving the performance of the MEMS sensor. The dry film polymer material generally has good flexibility and plasticity, which is easy to process and integrate into the MEMS sensor.

[0056] In a further embodiment, in step S400, the following steps are also included:

[0057] The exposure energy and exposure focus of the exposure treatment are adjusted to adjust the cross-linking degree and exposure depth of the polymer film layer.

[0058] In this embodiment, when light is irradiated on the mask, dense lines will produce strong diffraction light when out of focus, and interference will be formed between adjacent diffraction lights, thereby reducing the intensity. At low energy, the exposure depth will be significantly reduced, and therefore the surface of the polymer film layer will be exposed to light to form a photochemical reaction, and the lower part of the polymer film layer will not be exposed to light and no photochemical reaction will occur, which provides the necessary conditions for forming a cantilever structure. Since the dense line spacing of different sizes is designed on the mask, the diffraction of small-sized dense lines is relatively strong, and the interference is also correspondingly strengthened. Therefore, the light intensity distributed on the polymer surface will also be strong and weak, providing the necessary conditions for forming a drooping structure. The setting of the exposure focal length will affect the flatness of the surface of the drooping cantilever structure 100. When the focal length is set closer to the optimal imaging focus, the surface of the drooping cantilever structure 100 is uneven. When the focal length is set farther from the optimal imaging focus, the surface of the drooping cantilever structure 100 is relatively flat.

[0059] In this embodiment, the exposure time in the exposure process is any value in the range of 100ms-150ms, and the exposure focal length is any value in the range of -6μm to -15μm, so as to prepare a drooping cantilever beam structure 100 with a drooping depth of any value in the range of 1.0μm-3.0μm. That is, the exposure time can be 100ms,

[0060] 110ms, 120ms, 130ms, 140ms or 150ms, or any value between 100ms and 150ms. The exposure focal length can be -6μm, -7μm, -8μm, -9μm, -10μm, -11μm, -12μm, -

[0061] 13μm, -14μm or -15μm, or any value in the range of -6μm-15μm. For example, the exposure time is 100ms, the exposure focal length is -9μm, and the drooping cantilever beam structure 100 with a drooping depth of 2.05μm is prepared.

[0062] In this embodiment, when the exposure time is greater than 100ms, the prepared cantilever beam structure has an upturned structure. When the exposure time is 100ms and the exposure focal length is -6μm to 9μm, the surface of the prepared cantilever beam structure is uneven and has a bumpy shape. When the exposure time is 150ms and the exposure focal length is greater than 12μm, the surface of the prepared cantilever beam structure is uneven and has a bumpy shape.

[0063] In a further embodiment, in step S400, the method for preparing the drooping cantilever beam structure 100 further includes the following steps:

[0064] After the polymer film layer is exposed, a post-exposure baking process is performed on the polymer film layer.

[0065] In this embodiment, after the polymer film layer is exposed, the polymer film layer is heated to allow the molecular chains to reorganize with each other to form larger molecular chains. The reorganized molecular chains will not dissolve in the developer, while the unreorganized molecular chains will dissolve in the developer, thereby preparing a drooping cantilever beam structure 100 with a preset depth after development. Here, during the post-exposure baking process, the polymer film layer is first placed at 65° C. for 30 minutes, and then baked at 95° C. for 25 minutes.

[0066] In a further embodiment, after step S400, the method for preparing the drooping cantilever beam structure 100 further includes the following steps:

[0067] After the polymer film layer is developed, the polymer film layer is cured.

[0068] In this embodiment, after the polymer film layer is developed, the polymer film layer is cured by baking to cure the polymer film layer and improve the corrosion resistance and mechanical strength of the drooping cantilever structure 100. In addition, the curing treatment can also enhance the adhesion between the polymer film layer and the substrate 200. Here, the curing treatment is carried out in an oven, that is, the polymer film layer is baked in the oven to achieve the curing treatment, the baking time is 60 minutes, the baking temperature is 280°C, and the protective atmosphere during the baking process is nitrogen.

[0069] In a further embodiment, after step S200, the method for preparing the drooping cantilever beam structure 100 further includes the following steps:

[0070] The substrate 200 and the polymer film layer are subjected to a heating process.

[0071] In this embodiment, the substrate 200 and the polymer film layer are subjected to a heat treatment to increase the adhesion between the polymer film layer and the substrate 200, improve the uniformity of the polymer film layer, increase the modeling strength of the polymer film layer, and effectively remove the solvent in the polymer film layer. Here, during the heating treatment, the polymer film layer is first placed at 65° C. and baked for 10 minutes, and then baked at 95° C. for 20 minutes.

[0072] In a further embodiment, in step S100, the method for preparing the drooping cantilever beam structure 100 further includes the following steps:

[0073] The substrate 200 is sequentially subjected to plasma cleaning, wet cleaning and dehydration baking.

[0074] In this embodiment, before the polymer film layer is coated on the top surface of the substrate 200, the substrate 200 is sequentially subjected to plasma cleaning, wet cleaning and dehydration baking, that is, plasma cleaning can remove organic matter remaining on the surface of the substrate 200, improve the surface cleanliness, thereby enhancing the adhesion between the polymer film layer and the substrate 200, and improving the stability and reliability of the polymer film layer. Plasma cleaning can also perform micro-machining on the surface of the substrate 200, for example, roughening the surface of the substrate 200 to provide a better base for subsequent polymer film layer coating. Wet cleaning uses a cleaning liquid such as a chemical solvent or deionized water to deeply clean the substrate 200 by soaking, spraying, etc., to remove contaminants that may not be completely removed by plasma cleaning. Dehydration baking removes moisture from the surface of the substrate 200 by heating the substrate 200 to ensure that the surface of the substrate 200 is clean and dry. In a preferred embodiment, the power of plasma cleaning is 800 W, the cleaning time is 8 minutes, the wet cleaning method is SPM (Sulfuric Peroxide Mixture) cleaning, the baking temperature of dehydration baking is 200° C., and the baking time is 10 minutes.

[0075] In a further embodiment, the substrate 200 is made of silicon wafer or glass.

[0076] The present invention also provides a drooping cantilever structure 100, the drooping cantilever structure 100 includes a support portion 10 and at least one cantilever arm 20, the support portion 10 is located on the top surface of the substrate 200, and the support portion 10 is configured to protrude upward from the top surface of the substrate 200 toward a side away from the substrate 200, and the cantilever arm 20 is configured to protrude from the support portion 10 toward a side away from the support portion 10, wherein the drooping cantilever structure 100 is prepared according to the above-mentioned preparation method. Here, the number of cantilever arms 20 can be two or more, and the two cantilever arms 20 are symmetrically arranged about the center line of the support portion 10. The preparation method of the drooping cantilever structure 100 will not be described one by one here. The present invention also provides an application of a drooping cantilever structure 100 in a MEMS biosensor, and the drooping cantilever structure 100 is prepared according to the above-mentioned preparation method. The preparation method of the drooping cantilever structure 100 will not be described one by one here.

[0077] In this embodiment, the drooping cantilever beam structure 100 is applied to a MEMS biosensor, that is, the drooping cantilever beam structure 100 can be applied to various fluid detections in MEMS biosensors, for example, in vivo biological molecule concentration detection, protein adsorption and detection, and nanopore sequencing, etc. The drooping cantilever beam structure 100 in this embodiment has a larger size range, which can increase the detection range of the MEMS biosensor.

[0078] The preparation method of the drooping cantilever beam structure in the present application will be described below in conjunction with specific embodiments.

[0079] Embodiment 1

[0080] First, a silicon wafer substrate is provided, and the substrate is sequentially plasma cleaned, wet cleaned and dehydrated and baked, a polymer dry film layer is coated on the top surface of the silicon wafer substrate, and the substrate and the polymer dry film layer are heat-treated, that is, baked at 65°C for 10 minutes, and then baked at 95°C for 20 minutes, and then a mask with equal width and continuous lines / gaps is prepared, and the polymer dry film layer is sequentially exposed and developed using the mask, the exposure time of the exposure treatment is 100ms, the exposure focal length is -10μm, and after the exposure treatment, the polymer dry film layer is post-exposure baked, that is, baked at 65°C for 30 minutes, and then baked at 95°C for 25 minutes, the material of the polymer dry film layer is epoxy resin, and after the development treatment, the polymer dry film layer is cured, the curing temperature is 280°C, and the curing time is 60min, to prepare a drooping cantilever structure.

[0081] Table 1. Dimensions of the drooping cantilever structure at different positions in the wafer prepared in Example 1

[0082]

[0083] As shown in Table 1, by using a polymer material as the polymer film layer, adjusting the line / space width of the mask, the exposure time and exposure focal length during the exposure process, and the baking temperature after the exposure process and the development process, a drooping cantilever beam structure 100 with different drooping depths can be prepared. The slicing position refers to the drooping cantilever beam structure 100 at the top, bottom, left, right, and middle positions of the wafer surface when the wafer is placed horizontally.

[0084] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a drooping cantilever beam structure, characterized in that: The drooping cantilever structure comprises a support portion and at least one cantilever arm, wherein the cantilever arm is arranged to protrude from the support portion toward a side away from the support portion, and the preparation method comprises the following steps: providing a substrate; Coating at least one polymer film layer on the top surface of the substrate; Prepare a mask having continuous lines / spaces with a preset width; The polymer film layer is sequentially exposed and developed using the mask to prepare the drooping cantilever beam structure in the polymer film layer; wherein, The drooping depth of the drooping cantilever beam structure increases as the preset width decreases.

2. The preparation method according to claim 1, characterized in that: The material of the polymer film layer is polymer material.

3. The preparation method according to claim 2, characterized in that: The step of sequentially performing an exposure process and a development process on the polymer film layer using the mask to prepare the drooping cantilever beam structure in the polymer film layer further includes the following steps: The exposure energy and exposure focus of the exposure process are adjusted to adjust the crosslinking degree and exposure depth of the polymer film layer.

4. The preparation method according to claim 3, characterized in that: The step of sequentially exposing and developing the polymer film layer using the mask to prepare the drooping cantilever beam structure in the polymer film layer further includes the following steps: After the polymer film layer is exposed, the polymer film layer is subjected to a post-exposure baking treatment.

5. The preparation method according to claim 4, characterized in that: The step of sequentially exposing and developing the polymer film layer using the mask to prepare the drooping cantilever beam structure in the polymer film layer further includes the following steps: After the polymer film layer is developed, the polymer film layer is cured.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The step of coating at least one polymer film layer on the top surface of the substrate further includes the following steps: The substrate and the polymer film layer are subjected to a heating treatment.

7. The preparation method according to claim 6, characterized in that: The step of providing a substrate further includes the following steps: The substrate is sequentially subjected to plasma cleaning, wet cleaning and dehydration baking.

8. The preparation method according to claim 7, characterized in that: The substrate is made of silicon wafer or glass.

9. A drooping cantilever beam structure, characterized in that: include: A support portion, located on the top surface of the substrate, and the support portion is configured to protrude upward from the top surface of the substrate toward a side away from the substrate; At least one cantilever arm, the cantilever arm is arranged to protrude from the support portion toward a side away from the support portion; wherein, The drooping cantilever beam structure is prepared according to the preparation method described in any one of claims 1-8.

10. An application of a drooping cantilever beam structure in a bio-MEMS sensor, characterized in that: The drooping cantilever beam structure is prepared according to the preparation method described in any one of claims 1-8.

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