Diaphragm and MEMS acoustic device
By using a sandwich structure of a polycrystalline silicon base layer and an antimony reinforcement layer in the diaphragm of a MEMS acoustic device, the problem of low sensitivity of traditional diaphragms is solved, and efficient electrical signal conversion and sensitivity improvement are achieved during diaphragm vibration.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- RONGCHENG GOERTEK MICROELECTRONICS CO LTD
- Filing Date
- 2022-12-14
- Publication Date
- 2026-05-29
Smart Images
Figure CN116156394B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of acoustic materials technology, specifically, this application relates to a diaphragm and a MEMS acoustic device. Background Technology
[0002] Micro-Electro-Mechanical System (MEMS) microphones are microphones manufactured based on MEMS technology. Due to their advantages such as small package size, high reliability, and low cost, they have been widely used in various voice devices.
[0003] MEMS microphones typically consist of a substrate and a backplate and a diaphragm formed on the substrate. A gap exists between the backplate and the diaphragm, allowing them to together form a planar capacitor sensing structure. However, traditional diaphragms are relatively stiff, resulting in lower sensitivity during vibration and reducing the sound pickup performance of the MEMS microphone. Summary of the Invention
[0004] One objective of this application is to provide a new technical solution for diaphragms and MEMS acoustic devices that can solve the problem of low sensitivity of traditional diaphragms.
[0005] According to a first aspect of the embodiments of this application, a diaphragm is provided for use in a MEMS acoustic device, comprising:
[0006] The base layer is a polycrystalline silicon layer;
[0007] A reinforcing layer, wherein the reinforcing layer is an antimony layer, and the reinforcing layer is disposed on at least one surface of the base layer;
[0008] The thickness of the diaphragm ranges from 0.5 to 3 μm, and the electron mobility of the reinforcing layer is greater than that of the base layer.
[0009] Optionally, the electron mobility of the reinforcing layer ranges from 1000 to 20000 cm⁻¹. 2 / (V·s).
[0010] Optionally, the antimonide layer is made of antimonide type II superlattice, which includes one or a combination of InAs / GaSb and InAs / InAsSb.
[0011] Optionally, the reinforcing layer includes a first reinforcing layer and a second reinforcing layer, which are respectively disposed on both sides of the base layer.
[0012] Optionally, the thickness of the base layer ranges from 0.1 to 1 μm.
[0013] Optionally, the thickness of the first reinforcing layer is in the range of 0.2-2 μm, and the thickness of the second reinforcing layer is in the range of 0.2-2 μm.
[0014] Optionally, the thickness of the first reinforcing layer and the thickness of the second reinforcing layer are equal, and the ratio of the thickness of the first reinforcing layer to the thickness of the base layer is in the range of (1:1)-(4:1).
[0015] Optionally, the hardness of the reinforcing layer is less than the hardness of the base layer.
[0016] Optionally, the dark current density of the reinforcing layer is less than that of the base layer.
[0017] According to a second aspect of the embodiments of this application, a MEMS acoustic device is provided, the MEMS acoustic device including a substrate, a support layer, a back electrode plate and the diaphragm described in the first aspect;
[0018] The support layer is disposed on the substrate, the back electrode plate is connected to the hollow region of the support layer away from the substrate, and the diaphragm is connected to the hollow region of the support layer near the substrate, forming a gap between the diaphragm and the back electrode plate.
[0019] One technical advantage of this application is:
[0020] This application provides a diaphragm comprising a base layer and a reinforcing layer. The base layer is a polycrystalline silicon layer, and the reinforcing layer is an antimony layer disposed on at least one surface of the base layer. The thickness of the diaphragm ranges from 0.5 to 3 μm, and the electron mobility of the reinforcing layer is greater than that of the base layer. In this diaphragm, when the electron mobility of the reinforcing layer is greater than that of the base layer, the charging and discharging speed of the diaphragm can be improved by using the antimony-formed reinforcing layer, thus ensuring the sensitivity of the diaphragm during vibration.
[0021] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description
[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.
[0023] Figure 1 A schematic diagram of a diaphragm provided in an embodiment of this application;
[0024] Figure 2 for Figure 1 A magnified view of a portion of the image;
[0025] Figure 3 This is a schematic diagram of a MEMS acoustic device provided in an embodiment of this application.
[0026] in:
[0027] 100. Diaphragm; 1. Base layer; 2. Reinforcing layer; 21. First reinforcing layer; 22. Second reinforcing layer;
[0028] 200, Substrate; 300, Support layer; 400, Back electrode plate. Detailed Implementation
[0029] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present application.
[0030] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.
[0031] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.
[0032] In all the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.
[0033] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.
[0034] Reference Figure 1 This application provides a diaphragm that can be applied to MEMS acoustic devices such as MEMS microphones or MEMS speakers. The diaphragm includes:
[0035] The diaphragm consists of a base layer 1 and a reinforcing layer 2. The base layer 1 is a polycrystalline silicon layer, specifically made of polycrystalline silicon material. The polycrystalline silicon layer can provide the diaphragm with appropriate strength and prevent the diaphragm from having an excessive amplitude.
[0036] See Figure 1The reinforcing layer 2 is an antimony layer, specifically, it can be made of antimony material. The reinforcing layer 2 is disposed on at least one side surface of the base layer 1. In one example, the reinforcing layer 2 is a single layer, disposed on the upper or lower surface of the base layer 1; in another example, the reinforcing layer 2 is two layers, disposed on the upper and lower surfaces of the base layer 1 respectively.
[0037] The thickness of the diaphragm ranges from 0.5 to 3 μm. Specifically, when the diaphragm uses a high-hardness polycrystalline silicon layer as the base layer 1, the diaphragm can maintain its structural integrity during frequent vibration while keeping its thickness low. The electron mobility of the reinforcing layer 2 is greater than that of the base layer 1. In other words, the charging and discharging speed of the diaphragm can be improved by the reinforcing layer 2 formed by antimony, thus ensuring the sensitivity and compliance of the diaphragm during vibration.
[0038] Specifically, the reinforcing layer 2 can be formed on at least one side of the base layer 1 by deposition, then patterned on the diaphragm by photolithography, and finally etched by buffered oxide etch (BOE) to form the complete diaphragm, so as to facilitate the application of the diaphragm in MEMS acoustic devices such as MEMS microphones or MEMS speakers.
[0039] The diaphragm provided in this embodiment includes a base layer 1 and a reinforcing layer 2. The base layer 1 is a polycrystalline silicon layer, and the reinforcing layer 2 is an antimony layer. The reinforcing layer 2 is disposed on at least one surface of the base layer 1. The thickness of the diaphragm ranges from 0.5 to 3 μm. The electron mobility of the reinforcing layer 2 is greater than that of the base layer 1. That is, the charging and discharging speed of the diaphragm can be improved by the reinforcing layer 2 formed by the antimony, thereby ensuring the sensitivity and compliance of the diaphragm during vibration.
[0040] Optionally, the electron mobility of the reinforcing layer 2 is in the range of 1000-20000 cm⁻¹. 2 / (V·s).
[0041] Specifically, the diaphragm can convert vibration signals into electrical signals during vibration to facilitate sound control of the MEMS acoustic device, which requires the diaphragm to have a high charging and discharging speed; while the electron mobility of the base layer 1 is generally in the range of 50-200 cm⁻¹. 2 The conductivity of the diaphragm is limited by the coefficient of friction (V·s); while the electron mobility of the reinforcing layer 2 ranges from 1000 to 20000 cm⁻¹. 2 / (V·s), meaning that the electron mobility of the reinforcing layer 2 is at least an order of magnitude greater than that of the base layer 1, which can significantly improve the electrical conductivity of the diaphragm and increase the efficiency of the diaphragm in converting vibration signals into electrical signals during vibration.
[0042] Optionally, the antimonide layer is made of antimonide type II superlattice, which includes one or a combination of InAs / GaSb and InAs / InAsSb.
[0043] Specifically, the antimonide type II superlattice material has the characteristics of large effective electron mass, good uniformity and fast response rate. When the reinforcing layer 2 is prepared by the antimonide type II superlattice material, the antimonide type II superlattice material can be used to improve the overall electron mobility of the diaphragm and ensure the sensitivity of the diaphragm during vibration.
[0044] Optionally, see Figure 1 The reinforcing layer 2 includes a first reinforcing layer 21 and a second reinforcing layer 22, which are respectively disposed on the two sides of the base layer 1.
[0045] Specifically, when the first reinforcing layer 21 and the second reinforcing layer 22 are respectively disposed on the two sides of the base layer 1, a "sandwich" structure diaphragm can be formed, so that the first reinforcing layer 21 and the second reinforcing layer 22 are directly exposed after covering the base layer 1. The charging and discharging speed of the diaphragm is improved by the first reinforcing layer 21 and the second reinforcing layer 22, ensuring the sensitivity of the diaphragm during vibration.
[0046] Optionally, see Figure 2 The thickness H1 of the base layer 1 ranges from 0.1 to 1 μm.
[0047] Specifically, when the diaphragm uses a high-hardness polycrystalline silicon layer as the base layer 1, the diaphragm can maintain its structural integrity during frequent vibrations while keeping its thickness low. The thickness H1 of the base layer 1 can be selected from 0.1μm, 0.2μm, 0.5μm, 0.8μm, or 1μm. For example, when the area of the diaphragm is small, the thickness of the base layer 1 can be 0.1μm or 0.2μm, and when the area of the diaphragm is large, the thickness of the base layer 1 can be 0.8μm or 1μm.
[0048] Optionally, see Figure 2 The thickness H2 of the first reinforcing layer 21 ranges from 0.2 to 2 μm, and the thickness H3 of the second reinforcing layer 22 ranges from 0.2 to 2 μm.
[0049] Specifically, when the first reinforcing layer 21 and the second reinforcing layer 22 are formed by antimony, both the first reinforcing layer 21 and the second reinforcing layer 22 can have high electron mobility; when the thickness of the first reinforcing layer 21 and the second reinforcing layer 22 is in the range of 0.2-2 μm, the charging and discharging speed of the diaphragm can be improved, and the sensitivity of the diaphragm during vibration can be guaranteed.
[0050] Optionally, see Figure 1 and Figure 2 The thickness H2 of the first reinforcing layer 21 and the thickness H3 of the second reinforcing layer 22 are equal, and the ratio of the thickness H2 of the first reinforcing layer 21 to the thickness H1 of the base layer 1 is in the range of (1:1)-(4:1).
[0051] Specifically, when the thickness H2 of the first reinforcing layer 21 and the thickness H3 of the second reinforcing layer 22 are equal, the symmetry of the diaphragm in the thickness direction can be guaranteed, and the stability of the diaphragm during vibration can be improved; and when the ratio of the thickness H2 of the first reinforcing layer 21 to the thickness H1 of the base layer 1 is in the range of (1:1)-(4:1), the thickness H2 of the first reinforcing layer 21 and the thickness H3 of the second reinforcing layer 22 are both greater than or equal to the thickness H1 of the base layer 1, so as to ensure the charging and discharging speed of the diaphragm.
[0052] In one embodiment, the diaphragm has a thickness of 1 μm, wherein the base layer 1 has a thickness of 0.4 μm, the first reinforcing layer 21 has a thickness of 0.2 μm, and the second reinforcing layer 22 has a thickness of 0.4 μm, to form a "sandwich" type diaphragm structure.
[0053] Optionally, the hardness of the reinforcing layer 2 is less than the hardness of the base layer 1.
[0054] Specifically, when the diaphragm uses a high-hardness polycrystalline silicon layer as the base layer 1, the polycrystalline silicon layer is brittle and the diaphragm is prone to breakage when the amplitude of the diaphragm is too large. The reinforcing layer 2 formed by antimony has the characteristics of high flexibility and low hardness. When the reinforcing layer 2 and the base layer 1 are combined, the bending deformation ability of the diaphragm can be improved, ensuring the mechanical reliability of the diaphragm.
[0055] Specifically, the reinforcing layer 2 has a Mohs hardness range of 3-5, and the base layer 1 has a Mohs hardness range of 6-8.
[0056] Optionally, the dark current density of the reinforcing layer 2 is less than the dark current density of the base layer 1.
[0057] Specifically, when the diaphragm does not need to convert between vibration signals and electrical signals, that is, when no current is passed through the diaphragm, the dark current density of the reinforcing layer 2 can be as low as 2.0-100×10⁻⁶. -9 A / cm 2 The range is such that the reinforcing layer 2 can cover the base layer 1 to reduce the noise of the diaphragm.
[0058] See Figure 3 This application provides a MEMS acoustic device, which includes a substrate 200, a support layer 300, a back electrode plate 400 and the diaphragm 100.
[0059] The support layer 300 is disposed on the substrate 200, the back electrode plate 400 is connected to the hollow region of the support layer 300 away from the substrate 200, and the diaphragm 100 is connected to the hollow region of the support layer 300 near the substrate 200, forming a gap between the diaphragm 100 and the back electrode plate 400.
[0060] Specifically, the MEMS acoustic device can be a MEMS microphone or a MEMS speaker. The diaphragm in the MEMS acoustic device includes a base layer 1 and a reinforcing layer 2. The base layer 1 is a polycrystalline silicon layer, and the reinforcing layer 2 is an antimony layer. The reinforcing layer 2 is disposed on at least one surface of the base layer 1. The thickness of the diaphragm ranges from 0.5 to 3 μm. The electron mobility of the reinforcing layer 2 is greater than that of the base layer 1. That is, the charging and discharging speed of the diaphragm can be improved by the reinforcing layer 2 formed by antimony, ensuring the sensitivity and compliance of the diaphragm during vibration and improving the acoustic performance of the MEMS acoustic device.
[0061] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.
Claims
1. A diaphragm used in MEMS acoustic devices, characterized in that, include: The base layer (1) is a polycrystalline silicon layer; A reinforcing layer (2) is an antimony layer, and the reinforcing layer (2) is disposed on at least one side surface of the base layer (1); The thickness of the diaphragm is in the range of 0.5-3μm, and the electron mobility of the reinforcing layer (2) is greater than that of the base layer (1). The reinforcing layer (2) includes a first reinforcing layer (21) and a second reinforcing layer (22), which are respectively disposed on both sides of the base layer (1) and directly exposed. The dark current density of the reinforcing layer (2) is less than that of the base layer (1).
2. The diaphragm according to claim 1, characterized in that, The electron mobility of the reinforcing layer (2) is in the range of 1000-20000 cm⁻¹. 2 ∕(V·s).
3. The diaphragm according to claim 1, characterized in that, The antimonide layer is made of antimonide type II superlattice, which includes one or a combination of InAs / GaSb and InAs / InAsSb.
4. The diaphragm according to claim 1, characterized in that, The thickness of the base layer (1) ranges from 0.1 to 1 μm.
5. The diaphragm according to claim 1, characterized in that, The thickness of the first reinforcing layer (21) ranges from 0.2 to 2 μm, and the thickness of the second reinforcing layer (22) ranges from 0.2 to 2 μm.
6. The diaphragm according to claim 1, characterized in that, The thickness of the first reinforcing layer (21) is equal to the thickness of the second reinforcing layer (22), and the ratio of the thickness of the first reinforcing layer (21) to the thickness of the base layer (1) is in the range of (1:1)-(4:1).
7. The diaphragm according to claim 1, characterized in that, The hardness of the reinforcing layer (2) is less than that of the base layer (1).
8. A MEMS acoustic device, characterized in that, It includes a base (200), a support layer (300), a back electrode plate (400), and a diaphragm (100) as described in any one of claims 1-7. The support layer (300) is disposed on the substrate (200), the back electrode plate (400) is connected to the hollow region of the support layer (300) away from the substrate (200), and the diaphragm (100) is connected to the hollow region of the support layer (300) near the substrate (200) and forms a gap with the back electrode plate (400).