MEMS device and preparation method thereof

Abstract

The invention discloses an MEMS device and a preparation method thereof, and the preparation method comprises the steps: providing a substrate, and forming a cavity in the upper part of the substrate; a first sacrificial layer is formed in the cavity, and the upper surface of the first sacrificial layer is flush with the upper surface of the substrate; a stacked film layer is formed on the substrate, and the stacked film layer comprises a second sacrificial layer, a vibrating diaphragm layer located on the second sacrificial layer, a third sacrificial layer located on the vibrating diaphragm layer and a backboard layer located on the third sacrificial layer; forming a first through hole exposing the first sacrificial layer in the stacked film layer, and forming a second through hole exposing the third sacrificial layer in the backboard layer; forming a back cavity exposing the first sacrificial layer and the second sacrificial layer in the substrate; releasing the first sacrificial layer, the second sacrificial layer and the third sacrificial layer; wherein the vibrating diaphragm layer is a full diaphragm, and the first through hole is communicated with the back cavity through the concave cavity. According to the technical scheme, the diaphragm can be effectively prevented from being broken during diaphragm pasting.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically to a MEMS device and its fabrication method. Background Technology

[0002] MEMS (Micro-Electro-Mechanical System) microphones used in electronic cigarettes require a full-diaphragm due to special functional requirements and oil and dirt resistance. That is, the diaphragm does not have venting structures such as vent holes or venting grooves.

[0003] Because there is no venting structure on the diaphragm, it is prone to rupture due to instantaneous air pressure when the adhesive film is applied and a vacuum is drawn.

[0004] Therefore, improvements are needed to at least partially address the aforementioned problems. Summary of the Invention

[0005] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. The summary section of this invention is not intended to limit the key features and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0006] To at least partially solve the above-mentioned problems, according to a first aspect of the present invention, a method for fabricating a MEMS device is provided, comprising: A substrate is provided, and a cavity is formed on the upper part of the substrate; A first sacrificial layer is formed within the cavity, wherein the upper surface of the first sacrificial layer is flush with the upper surface of the substrate; A stacked film layer is formed on the substrate, wherein the stacked film layer includes a second sacrificial layer, a diaphragm layer located on the second sacrificial layer, a third sacrificial layer located on the diaphragm layer, and a backplate layer located on the third sacrificial layer; A first through-hole is formed in the stacked film layer to expose the first sacrificial layer, and a second through-hole is formed in the backing layer to expose the third sacrificial layer; A back cavity is formed in the substrate to expose the first sacrificial layer and the second sacrificial layer; Release the first sacrificial layer, the second sacrificial layer, and the third sacrificial layer; The diaphragm layer is a full-film structure, and the first through-hole communicates with the back cavity through the concave cavity.

[0007] For example, the first sacrificial layer includes a first sub-sacrificial layer, a second sub-sacrificial layer and a third sub-sacrificial layer stacked together, wherein the second sub-sacrificial layer is located between the first sub-sacrificial layer and the third sub-sacrificial layer; The release rate of the second sub-sacrificial layer is greater than that of the first sub-sacrificial layer and the third sub-sacrificial layer.

[0008] For example, both the first sub-sacrificial layer and the third sub-sacrificial layer are made of silicon oxide; The material of the second sub-sacrificial layer includes PSG.

[0009] For example, the stacked film layers further include a protective layer located below the first sacrificial layer and at least partially covering the first sacrificial layer; The diaphragm layer includes a diaphragm body and at least one annular support portion located on the lower side of the diaphragm body. The diaphragm body is located on the second sacrificial layer, and the annular support portion is located in the second sacrificial layer and partially located on the protective layer. The backplate layer covers the circumferential side surface of the second sacrificial layer, the circumferential side surface of the diaphragm body, and the circumferential side surface of the third sacrificial layer; The back cavity exposes the second sacrificial layer located inside the innermost annular support portion; The second sacrificial layer between adjacent annular support portions and the second sacrificial layer between the outermost annular support portion and the backplate layer are both isolated from the first sacrificial layer by the protective layer and are not released.

[0010] For example, both the second sacrificial layer and the third sacrificial layer are silicon oxide layers.

[0011] For example, the protective layer may be made of silicon nitride.

[0012] For example, there are at least two cavities.

[0013] For example, the diaphragm layer is made of polycrystalline silicon; The material of the backsheet layer includes silicon nitride.

[0014] According to a second aspect of the present invention, a MEMS device is provided, comprising: A substrate having a back cavity and a recess communicating with the back cavity; A stacked film layer is located on the substrate. The stacked film layer includes a support layer, a diaphragm layer located on the support layer, and a backplate layer located on the diaphragm layer. The diaphragm layer has a lower cavity communicating with the back cavity on the side facing the back cavity, and an upper cavity between the diaphragm layer and the backplate layer. The diaphragm layer is a full-film structure, the stacked film layers have a first through hole communicating with the cavity, and the backplate layer has a second through hole communicating with the upper cavity.

[0015] For example, the stacked film layer further includes a protective layer located below the support layer and at least partially covering the cavity; The diaphragm layer includes a diaphragm body and at least one annular support portion located on the lower side of the diaphragm body. The diaphragm body is located on the support layer, and the annular support portion is partially located on the protective layer. The backplate layer covers the circumferential side surface of the diaphragm body and the circumferential side surface of the support layer; The lower cavity is located inside the innermost annular support portion; The support layer is located between the outermost annular support portion and the back plate layer, or the support layer is located between the outermost annular support portion and the back plate layer and between adjacent annular support portions, and the support layer is spaced apart from the cavity by the protective layer.

[0016] According to the MEMS device and its fabrication method of the present invention, a concave cavity and a first through hole are formed that communicate with the back cavity. The concave cavity and the first through hole can serve as venting channels to achieve venting when the adhesive film is pasted on the underside of the substrate, thereby preventing the diaphragm layer from being ruptured due to air pressure. Attached Figure Description

[0017] The following figures are included as part of this application for understanding the application. The figures illustrate embodiments of the application and their descriptions, serving to explain the apparatus and principles of the application. In the figures, Figure 1 This is a schematic flowchart of a method for fabricating a MEMS device according to an embodiment of this application; Figures 2A-2G A top view schematic diagram of the structure corresponding to each step of the fabrication method of a MEMS device according to an embodiment of this application; Figures 3A-3G They are respectively Figures 2A-2G Schematic diagram of cross-section at point AA.

[0018] Explanation of reference numerals in the attached figures: 100-Substrate, 110-Cavity, 120-Back cavity, 200-First sacrificial layer, 210-First sub-sacrificial layer, 220-Second sub-sacrificial layer, 230-Third sub-sacrificial layer, 300-Stacked film layers, 301-First through-hole, 302-Second through-hole, 303-Lower cavity, 304-Upper cavity, 310-Protective layer, 320-Second sacrificial layer, 321-Support layer, 330-Diaphragm layer, 331-Diaphragm body, 332-Annular support, 340-Third sacrificial layer, 350-Backplate layer, 351-Backplate body, 3511-Protrusion, 352-Dielectric layer, 400-Adhesive film. Detailed Implementation

[0019] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0020] It should be understood that this application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this application to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0021] It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or parts, these elements, components, areas, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or part from another element, component, area, layer, or part. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or part discussed below may be referred to as the second element, component, area, layer, or part.

[0022] Spatial relation terms such as "below," "under," "below," "under," "above," and "above" are used here for convenience to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms are intended to also include different orientations of devices in use and operation.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0024] Embodiments of the invention are described herein with reference to cross-sectional views that serve as schematic diagrams of preferred embodiments (and intermediate structures) of this application. Thus, variations in the shown shape are contemplated due to, for example, manufacturing techniques and / or tolerances. Therefore, embodiments of this application should not be limited to the specific shapes shown herein, but include shape deviations due to, for example, manufacturing processes. Consequently, the figures are substantially schematic, and their shapes are not intended to show the actual shape of the device and are not intended to limit the scope of this application.

[0025] See attached document Figure 1 An exemplary description will be given of a method for fabricating a MEMS device according to an embodiment of this application. The MEMS device can be a MEMS microphone. The fabrication method includes the following steps: S10: Provide a substrate and form a cavity on the upper part of the substrate.

[0026] S20: A first sacrificial layer is formed within the cavity. The upper surface of the first sacrificial layer is flush with the upper surface of the substrate.

[0027] S30: Forming a stacked film layer on a substrate. The stacked film layer includes a second sacrificial layer, a diaphragm layer on the second sacrificial layer, a third sacrificial layer on the diaphragm layer, and a backplate layer on the third sacrificial layer.

[0028] S40: A first through-hole is formed in the stacked film layer to expose the first sacrificial layer, and a second through-hole is formed in the backsheet layer to expose the third sacrificial layer.

[0029] S50: Form a back cavity in the substrate that exposes the first sacrificial layer and the second sacrificial layer; S60: Release the first, second, and third sacrificial layers.

[0030] The diaphragm layer is a complete membrane, meaning it is an intact membrane layer without any venting holes or venting grooves. The first through hole connects to the back cavity through a recess.

[0031] According to the MEMS device fabrication method of the embodiments of this application, a concave cavity and a first through hole communicating with the back cavity are formed. The concave cavity and the first through hole can serve as venting channels to achieve venting when the adhesive film is pasted on the underside of the substrate, thereby preventing the diaphragm layer from being ruptured due to air pressure.

[0032] The following is a reference to the appendix. Figures 2A-2G , Figures 3A-3G A method for fabricating a MEMS device according to an embodiment of this application (i.e., steps S10-S60 described above) will be described in detail.

[0033] In step S10, see Appendix Figure 2A , Figure 3A ( Figure 3A for Figure 2A (See the cross-sectional view at point AA). A substrate 100 is provided, and a cavity 110 is formed on the upper part of the substrate 100. The cavity 110 is a groove on the upper part of the substrate 100. Exemplarily, a patterned mask layer is first formed on the substrate 100; then, the substrate 100 is etched using the mask layer as a mask to form the cavity 110; then, the mask layer is removed. The material of the substrate 100 can be any suitable semiconductor material well known to those skilled in the art, including but not limited to: germanium, silicon, etc. This application does not limit the material of the substrate 100. The depth of the cavity 110 is less than the thickness of the substrate 100. In this embodiment, there may be only one cavity 110 in the MEMS device; in some other embodiments, there may be at least two cavities 110.

[0034] In step S20, firstly, see Appendix Figure 2B , Figure 3B ( Figure 3B for Figure 2B (See the cross-sectional view at point AA). A first sacrificial layer 200 is formed on the upper surface of the substrate 100 and the inner surface of the cavity 110 using a deposition process. In this embodiment, the first sacrificial layer 200 includes a first sub-sacrificial layer 210, a second sub-sacrificial layer 220, and a third sub-sacrificial layer 230 stacked together, with the second sub-sacrificial layer 220 located between the first sub-sacrificial layer 210 and the third sub-sacrificial layer 230. The release rate of the second sub-sacrificial layer 220 is greater than that of the first sub-sacrificial layer 210 and the third sub-sacrificial layer 230. Therefore, when the first sacrificial layer 200 is subsequently released, the second sub-sacrificial layer 220 will be released rapidly, forming a channel between the first sub-sacrificial layer 210 and the third sub-sacrificial layer 230, accelerating the release of the first sub-sacrificial layer 210 and the third sub-sacrificial layer 230, thereby significantly improving the overall release rate of the first sacrificial layer 200. For example, the thickness of the first sacrificial layer 200 is greater than or equal to the depth of the cavity 110, and the sum of the thicknesses of the first sub-sacrificial layer 210 and the second sub-sacrificial layer 220 is less than the depth of the cavity 110.

[0035] For example, the first sub-sacrificial layer 210 and the third sub-sacrificial layer 230 are both made of silicon oxide, and the second sub-sacrificial layer 220 is made of PSG (Phosphosilicate Glass). For example, the first sub-sacrificial layer 210, the second sub-sacrificial layer 220, and the third sub-sacrificial layer 230 can be formed by a deposition process such as PECVD (Plasma-Enhanced Chemical Vapor Deposition).

[0036] Then, see appendix. Figure 2C , Figure 3C ( Figure 3C for Figure 2C (See the cross-sectional view at point AA). The first sacrificial layer 200 is polished using a CMP (Chemical Mechanical Polishing) process until the upper surface of the substrate 100 is exposed. The remaining first sacrificial layer 200 after polishing is located in the cavity 110, and the upper surface of the first sacrificial layer 200 is flush with the upper surface of the substrate 100.

[0037] In step S30, firstly, see Appendix Figure 2C , Figure 3C ( Figure 3C for Figure 2C (See the cross-sectional view at point AA). A patterned protective layer 310 is formed on the substrate 100 and the first sacrificial layer 200. In this embodiment, the stacked film layer 300 also includes the protective layer 310. Exemplarily, a protective layer 310 is first formed integrally on the substrate 100 and the first sacrificial layer 200 using a deposition process such as LPCVD (Low Pressure Chemical Vapor Deposition); then, a patterned mask layer is formed on the protective layer 310; then, the protective layer 310 is etched using the mask layer as a mask, and the etched remaining protective layer 310 at least partially covers the first sacrificial layer 200, that is, it can partially cover the first sacrificial layer 200 or completely cover the first sacrificial layer 200; then, the mask layer is removed. Exemplarily, the material of the protective layer 310 may include silicon nitride.

[0038] Then, see appendix. Figure 2D , Figure 3D ( Figure 3D for Figure 2D(See the cross-sectional view at point AA), which sequentially forms the second sacrificial layer 320, the diaphragm layer 330, the third sacrificial layer 340, and the backplate layer 350. For example, a patterned second sacrificial layer 320 is first formed on the substrate 100 and the protective layer 310 using deposition and etching processes. The second sacrificial layer 320 has at least one annular trench that penetrates the second sacrificial layer 320 and exposes a portion of the protective layer 310. Then, a diaphragm layer 330 is formed in the annular trench and on the second sacrificial layer 320 using deposition and planarization processes. The diaphragm layer 330 includes a diaphragm body 331 and at least one annular support portion 332 located below the diaphragm body 331. The diaphragm body 331 is located on the second sacrificial layer 320, and the annular support portion 332 is located in the second sacrificial layer 320, i.e., in the annular trench, and partially on the protective layer 310. When there are multiple annular support portions 332, the multiple annular support portions are coaxial and spaced apart. The arrangement of the annular support portions 332 can effectively enhance the structural strength and stability of the diaphragm layer 330. Then, the diaphragm layer 330 and the second sacrificial layer 320 are... The circumferential edges are etched to ensure that the diaphragm layer 330 and the second sacrificial layer 320 are within a predetermined size range, exposing a portion of the substrate 100 and a portion of the protective layer 310 located on the first sacrificial layer 200. Then, a third sacrificial layer 340 is formed on the diaphragm layer 330 through deposition and etching processes, wherein the vertical projection of the third sacrificial layer 340 does not exceed the range of the diaphragm layer 330. Then, a patterned dielectric layer 352 is formed on the third sacrificial layer 340, and a dielectric layer 352 is formed on the third sacrificial layer 340. Layer 352 serves as a mask to etch the third sacrificial layer 340, forming multiple trenches with a depth less than the thickness of the third sacrificial layer 340. Then, a backplate body 351 is formed in the trenches, on the substrate 100, and on the dielectric layer 352 using a deposition process. The backplate body 351 and the dielectric layer 352 together constitute the backplate layer 350, which covers the circumferential sides of the second sacrificial layer 320, the circumferential sides of the diaphragm body 331, and the circumferential sides of the third sacrificial layer 340. The backplate layer 350, composed of the backplate body 351 and the dielectric layer 352, improves the mechanical strength of the backplate layer 350 and prevents the suspended portion of the backplate layer 350 from collapsing after the upper cavity 304 is formed in subsequent steps. The backplate body 351 located in the trenches is a protrusion 3511, which prevents the diaphragm layer 330 from adhering to the backplate layer 350 during vertical vibration. For example, the second sacrificial layer 320 and the third sacrificial layer 340 are both made of silicon oxide, the diaphragm layer 330 is made of polycrystalline silicon, the dielectric layer 352 is made of polycrystalline silicon, and the backplate body 351 is made of silicon nitride. The diaphragm layer 330 is a full-film structure, meaning it is a complete film layer without any venting holes or venting grooves.It should be noted that the above-described stacked film layer 300 structure and formation method are merely examples. In other embodiments, the stacked film layer 300 may be other structures known to those skilled in the art, including a second sacrificial layer 320, a diaphragm layer 330 located on the second sacrificial layer 320, a third sacrificial layer 340 located on the diaphragm layer 330, and a backplate layer 350 located on the third sacrificial layer 340, as long as it can realize the MEMS device function (e.g., MEMS microphone function) after the subsequent sacrificial layer is released.

[0039] In step S40, see Appendix Figure 2D , Figure 3D ( Figure 3D for Figure 2D (See the cross-sectional view at point AA). A first via 301 is formed in the stacked film layer 300 to expose the first sacrificial layer 200, and a second via 302 is formed in the backplane layer 350 to expose the third sacrificial layer 340. For example, a patterned mask layer can be formed on the backplane layer 350, and then the backplane layer 350 and the protective layer 310 can be etched using the mask layer as a mask to form the first via 301 exposing the first sacrificial layer 200, after which the mask layer is removed. The second via 302 can be formed in the same manner as the first via 301, and will not be described again here.

[0040] In step S50, see Appendix Figure 2E , Figure 3E ( Figure 3E for Figure 2E (See the cross-sectional view at point AA). A back cavity 120 is formed in the substrate 100, exposing the first sacrificial layer 200 and the second sacrificial layer 320. For example, a patterned mask layer can be formed on the underside of the substrate 100, and then the substrate 100 can be etched using the mask layer as a mask to form the back cavity 120 exposing the first sacrificial layer 200 and the second sacrificial layer 320. In this embodiment, the back cavity 120 exposes the second sacrificial layer 320 located inside the innermost annular support portion 332, but does not expose the second sacrificial layer 320 between adjacent annular support portions 332 or the second sacrificial layer 320 between the outermost annular support portion 332 and the backplate layer 350. The second sacrificial layer 320 between adjacent annular support portions 332 and the second sacrificial layer 320 between the outermost annular support portion 332 and the backplate layer 350 are both isolated from the first sacrificial layer 200 by a protective layer 310, and do not directly contact the first sacrificial layer 200. Therefore, in the subsequent step S60, the second sacrificial layer 320 between adjacent annular support portions 332 and the second sacrificial layer 320 between the outermost annular support portion 332 and the backplate layer 350 will not be released, but will be retained as support layer 321 to support the mask layer.

[0041] In step S60, see Appendix Figure 2F , Figure 3F ( Figure 3F for Figure 2F (Cross-sectional view at point AA), releasing the first sacrificial layer 200, the second sacrificial layer 320, and the third sacrificial layer 340. Exemplarily, the first sacrificial layer 200, the second sacrificial layer 320, and the third sacrificial layer 340 are wet-etched using a wet etching solution to release them. Specifically, the second sacrificial layer 320 between adjacent annular support portions 332 and between the outermost annular support portion 332 and the backplate layer 350 is not released but is retained as support layer 321 to support the mask layer. After the first sacrificial layer 200 is released, the cavity 110 is exposed. After the second sacrificial layer 320 is released, a lower cavity 303 is formed below the diaphragm layer 330 and communicates with the back cavity 120. After the third sacrificial layer 340 is released, an upper cavity 304 is formed between the diaphragm layer 330 and the backplate layer 350. The first through hole 301 is connected to the back cavity 120 through the concave cavity 110.

[0042] After step S60, see Appendix Figure 2G , Figure 3G ( Figure 3G for Figure 2G (See the cross-sectional view at point AA). An adhesive film 400 can be adhered to the underside of the substrate 100, sealing the lower opening of the back cavity 120. Exemplarily, the adhesive film 400 can be used to maintain the integrity of the grains during subsequent dicing. Exemplarily, the adhesive film 400 can be a blue film (also known as electronic-grade tape) or a UV film. Exemplarily, the adhesive film 400 can be aligned with the lower side of the substrate 100, then a vacuum can be drawn to remove the cavity between them, and then the adhesive film 400 can be adhered to the lower side of the substrate 100. The first through-hole 301 communicates with the back cavity 120 through the recess 110. The recess 110 and the first through-hole 301 can serve as venting channels to release air during the adhesion of the adhesive film 400, preventing the diaphragm layer 330 from rupturing due to air pressure. Exemplarily, in some embodiments, the substrate 100 can be thinned before the adhesive film 400 is adhered.

[0043] Thus, the process steps of the MEMS device fabrication method according to the embodiments of this application are completed. It is understood that the MEMS device fabrication method of this embodiment includes not only the above steps, but may also include other necessary steps before, during or after the above steps, all of which are included in the scope of the fabrication method of this embodiment.

[0044] The following is a reference to the appendix. Figure 2F , Figure 3F ( Figure 3F for Figure 2F(A cross-sectional view at point AA) illustrates an embodiment of a MEMS device according to this application. The MEMS device can be fabricated using the methods described above. The microphone includes a substrate 100 and stacked film layers 300.

[0045] The substrate 100 has a back cavity 120 and a recess 110 communicating with the back cavity 120.

[0046] The stacked film layer 300 is located on the substrate 100. The stacked film layer 300 includes a support layer 321, a diaphragm layer 330 located on the support layer 321, and a back plate layer 350 located on the diaphragm layer 330. The diaphragm layer 330 has a lower cavity 303 communicating with the back cavity 120 on the side facing the back cavity 120, and an upper cavity 304 is provided between the diaphragm layer 330 and the back plate layer 350.

[0047] Among them, the diaphragm layer 330 is a full membrane, that is, the diaphragm layer 330 is a complete membrane layer, and the diaphragm layer 330 does not have venting structures such as venting holes and venting grooves. The stacked membrane layer 300 has a first through hole 301 that communicates with the cavity 110, and the back plate layer 350 has a second through hole 302 that communicates with the upper cavity 304.

[0048] According to the MEMS device of the present application embodiment, the first through hole 301 is connected to the back cavity 120 through the cavity 110. The cavity 110 and the first through hole 301 can serve as a venting channel to vent when the adhesive film 400 is pasted, so as to prevent the diaphragm layer 330 from being ruptured due to air pressure.

[0049] In this embodiment, the stacked diaphragm layer 300 further includes a protective layer 310, which is located below the support layer 321 and at least partially covers the cavity 110. The diaphragm layer 330 includes a diaphragm body 331 and at least one annular support portion 332 located below the diaphragm body 331. The diaphragm body 331 is located on the support layer 321, and the annular support portion 332 is partially located on the protective layer 310. The backplate layer 350 covers the circumferential side surfaces of the diaphragm body 331 and the support layer 321. The lower cavity 303 is located inside the innermost annular support portion 332. The support layer 321 is located between the outermost annular support portion 332 and the backplate layer 350, or, the support layer 321 is located between the outermost annular support portion 332 and the backplate layer 350 and between adjacent annular support portions 332, with the support layer 321 spaced from the cavity 110 by the protective layer 310. By setting the protective layer 310, the support layer 321 can be effectively formed when the first sacrificial layer 200 is formed, and it can be prevented from being released when the first sacrificial layer 200 is released, thereby effectively simplifying the preparation process.

[0050] It should be noted that the above-described structure of the stacked film layer 300 is only an example. In other embodiments, the stacked film layer 300 may be a structure known to those skilled in the art, including a support layer 321, a diaphragm layer 330 located on the support layer 321, and a backplate layer 350 located on the diaphragm layer 330, with a lower cavity 303 communicating with the back cavity 120 on the side of the diaphragm layer 330 facing the back cavity 120, and an upper cavity 304 between the diaphragm layer 330 and the backplate layer 350, as long as it can realize the function of MEMS device (e.g., MEMS microphone function).

[0051] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0052] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0053] Similarly, it should be understood that, in order to streamline this application and aid in understanding one or more of the various inventive aspects, features of this application may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, this approach should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, its inventive point lies in solving the corresponding technical problem with features fewer than all features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0054] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus so disclosed can be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature serving the same, equivalent, or similar purpose.

[0055] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0056] It should be noted that the above embodiments are illustrative of this application and not restrictive of this application, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.

Claims

1. A method for fabricating a MEMS device, characterized in that, include: A substrate is provided, and a cavity is formed on the upper part of the substrate; A first sacrificial layer is formed within the cavity, wherein the upper surface of the first sacrificial layer is flush with the upper surface of the substrate; A stacked film layer is formed on the substrate, wherein the stacked film layer includes a second sacrificial layer, a diaphragm layer located on the second sacrificial layer, a third sacrificial layer located on the diaphragm layer, and a backplate layer located on the third sacrificial layer; A first through-hole is formed in the stacked film layer to expose the first sacrificial layer, and a second through-hole is formed in the backing layer to expose the third sacrificial layer; A back cavity is formed in the substrate to expose the first sacrificial layer and the second sacrificial layer; Release the first sacrificial layer, the second sacrificial layer and the third sacrificial layer, wherein the diaphragm layer is a full-film diaphragm, and the first through hole communicates with the back cavity through the recess.

2. The preparation method according to claim 1, characterized in that, The first sacrificial layer includes a first sub-sacrificial layer, a second sub-sacrificial layer and a third sub-sacrificial layer stacked together, wherein the second sub-sacrificial layer is located between the first sub-sacrificial layer and the third sub-sacrificial layer; The release rate of the second sub-sacrificial layer is greater than that of the first sub-sacrificial layer and the third sub-sacrificial layer.

3. The preparation method according to claim 2, characterized in that, Both the first sub-sacrificial layer and the third sub-sacrificial layer are made of silicon oxide; The material of the second sub-sacrificial layer includes PSG.

4. The preparation method according to claim 1, characterized in that, The stacked film layers further include a protective layer located below the first sacrificial layer and at least partially covering the first sacrificial layer; The diaphragm layer includes a diaphragm body and at least one annular support portion located on the lower side of the diaphragm body. The diaphragm body is located on the second sacrificial layer, and the annular support portion is located in the second sacrificial layer and partially located on the protective layer. The backplate layer covers the circumferential side of the second sacrificial layer, the circumferential side of the diaphragm body, and the circumferential side of the third sacrificial layer; The back cavity exposes the second sacrificial layer located inside the innermost annular support portion; The second sacrificial layer between adjacent annular support portions and the second sacrificial layer between the outermost annular support portion and the backplate layer are both isolated from the first sacrificial layer by the protective layer and are not released.

5. The preparation method according to claim 4, characterized in that, Both the second sacrificial layer and the third sacrificial layer are silicon oxide layers.

6. The preparation method according to claim 4, characterized in that, The protective layer is made of silicon nitride.

7. The preparation method according to claim 1, characterized in that, There are at least two cavities.

8. The preparation method according to claim 1, characterized in that, The diaphragm layer is made of polycrystalline silicon; The material of the backsheet layer includes silicon nitride.

9. A MEMS device, characterized in that, include: A substrate having a back cavity and a recess communicating with the back cavity; A stacked film layer is located on the substrate. The stacked film layer includes a support layer, a diaphragm layer located on the support layer, and a backplate layer located on the diaphragm layer. The diaphragm layer has a lower cavity communicating with the back cavity on the side facing the back cavity, and an upper cavity between the diaphragm layer and the backplate layer. The diaphragm layer is a full-film structure, the stacked film layers have a first through hole communicating with the cavity, and the backplate layer has a second through hole communicating with the upper cavity.

10. The MEMS device according to claim 9, characterized in that, The stacked film layers also include a protective layer located below the support layer and at least partially covering the cavity; The diaphragm layer includes a diaphragm body and at least one annular support portion located on the lower side of the diaphragm body. The diaphragm body is located on the support layer, and the annular support portion is partially located on the protective layer. The backplate layer covers the circumferential side surface of the diaphragm body and the circumferential side surface of the support layer; The lower cavity is located inside the innermost annular support portion; The support layer is located between the outermost annular support portion and the back plate layer, or the support layer is located between the outermost annular support portion and the back plate layer and between adjacent annular support portions, and the support layer is spaced apart from the cavity by the protective layer.

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