Micro-electro-mechanical system sensor and electronic device

Abstract

The embodiment of the present disclosure discloses a micro-electro-mechanical system sensor and electronic equipment. The micro-electro-mechanical system sensor comprises a substrate layer, a first electrode layer and a support layer, the support layer is arranged between the first electrode layer and the substrate layer, so that a suspended space gap is formed between the first electrode layer and the substrate layer. One technical effect of the embodiment of the present disclosure is that the support layer is arranged between the first electrode layer and the substrate layer to form a suspended space gap. While increasing the distance between the first electrode layer and the substrate layer, the dielectric constant ε is also reduced, thereby increasing the output of the effective capacitance of the entire sensor.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical systems (MEMS) technology, and more specifically, to a microelectromechanical system sensor and electronic device. Background Technology

[0002] Existing voice acceleration sensors often have excessively high CP (coupling capacitance) values. The effective signal is affected by the excessive CP, resulting in low accuracy and greatly interfering with signal processing. This makes it impossible for headphones to achieve high-definition sound pickup and noise reduction in noisy environments. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a novel microelectromechanical system sensor and electronic device, which aims to solve at least one of the problems in the prior art.

[0004] According to one aspect of the present invention, a microelectromechanical system (MEMS) sensor is provided. The MEMS sensor includes:

[0005] Substrate layer and first electrode layer;

[0006] A support layer is disposed between the first electrode layer and the substrate layer to form a suspended gap between the first electrode layer and the substrate layer;

[0007] The second electrode layer is disposed on the side of the first electrode layer away from the substrate layer and opposite to the first electrode layer.

[0008] Optionally, the thickness of the support layer ranges from 1 to 20 micrometers.

[0009] Optionally, the thickness of the support layer ranges from 5 to 10 micrometers.

[0010] Optionally, the support layer is a silicon oxide layer or a silicon nitride layer.

[0011] Optionally, the second electrode layer has vent holes, and the vent holes and the suspension gap are opposite each other.

[0012] Optionally, the second electrode layer includes a first mass block, a second mass block, and a support portion. The support portion abuts against the first electrode layer, and the first mass block and the second mass block are connected to both sides of the support portion. The mass of the first mass block is greater than the mass of the second mass block.

[0013] Optionally, the microelectromechanical system sensor further includes a cover plate disposed on the side of the second electrode layer away from the substrate layer, the cover plate and the second electrode layer forming a vacuum chamber.

[0014] Optionally, the microelectromechanical system (MEMS) sensor is an accelerometer and a microphone.

[0015] Optionally, the microelectromechanical system sensor is a microphone, the first electrode layer is a back electrode plate, and the second electrode layer is a diaphragm.

[0016] According to another aspect of the present invention, an electronic device is provided. This electronic device includes a microelectromechanical system (MEMS) sensor as described in any one of the foregoing embodiments.

[0017] One technical advantage of this embodiment is that by placing the support layer between the first electrode layer and the substrate layer, a suspended gap is formed between the first electrode layer and the substrate layer. This increases the distance between the first electrode layer and the substrate layer while simultaneously reducing the dielectric constant ε between them, thereby improving the testing accuracy of the microelectromechanical system (MEMS) sensor.

[0018] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which form part of this specification, illustrate embodiments of the invention and, together with the specification, serve to explain the principles of the invention.

[0020] Figure 1 This is a schematic diagram of the structure of a microelectromechanical system sensor according to an embodiment of this disclosure;

[0021] Figure 2 This is a schematic diagram of the structure of a microelectromechanical system microphone according to an embodiment of this disclosure.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1. Substrate layer; 2. First electrode layer; 3. Support layer; 4. Suspension gap; 5. Second electrode layer; 51. Vent hole; 52. First mass block; 53. Second mass block; 54. Support part; 6. Cover plate. Detailed Implementation

[0024] Various exemplary embodiments of the present invention 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 invention.

[0025] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0026] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0027] 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.

[0028] 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.

[0029] This invention provides a microelectromechanical system (MEMS) sensor. MEMS sensors are a novel type of sensor manufactured using microelectronics and micromachining technologies. Compared to traditional sensors, they feature small size, light weight, low cost, low power consumption, high reliability, suitability for mass production, ease of integration, and the ability to achieve intelligent operation. MEMS sensors are commonly used in medical, automotive, and electronic product fields.

[0030] like Figure 1 As shown, the microelectromechanical system (MEMS) sensor provided by this invention includes a substrate layer 1, a first electrode layer 2, a second electrode layer 5, and a support layer 3. The support layer 3 is disposed between the first electrode layer 2 and the substrate layer 1, forming a cantilever gap 4 between the first electrode layer 2 and the substrate layer 1. The second electrode layer 5 is disposed on the side of the first electrode layer 2 away from the substrate layer 1 and opposite to the first electrode layer 2, forming a gap between the first electrode layer 2 and the second electrode layer 5.

[0031] The microelectromechanical system sensor provided by the present invention is a capacitive sensor, wherein the second electrode layer 5 is disposed on the side of the first electrode layer 2 away from the substrate layer 1 and opposite to the first electrode layer 2, and the first electrode layer 2 and the second electrode layer 5 form a capacitor.

[0032] A capacitive sensor is a device that uses various types of capacitors as sensing elements to convert the measured physical or mechanical quantity into a change in capacitance. Essentially, it's a capacitor with variable parameters. Capacitive sensors are widely used for measuring displacement, angle, vibration, velocity, pressure, composition analysis, and media properties.

[0033] Capacitive sensors generate coupling capacitance (CP) during operation. CP primarily arises from the capacitor effect between the lower electrode and the substrate. This coupling capacitance severely interferes with the output of the effective capacitance, significantly reducing and interfering with the overall acoustic performance of the sensor. The larger the CP value, the weaker the effective signal of the sensor. Due to the structural limitations of capacitive sensors, CP cannot be fundamentally eliminated; it can only be reduced through structural design, thereby relatively increasing the effective signal and improving the overall acoustic performance of the sensor. According to the principle of a parallel-plate capacitor, capacitance C = ε * ε0 * S / d, meaning that capacitance C is directly proportional to the dielectric constant ε of the dielectric and inversely proportional to the distance d between the two plates. Therefore, by reducing the dielectric constant ε or increasing the distance d between the two plates, capacitance C can be reduced, thereby reducing the CP value, relatively increasing the effective signal, and improving the accuracy of the sensor.

[0034] like Figure 1 As shown, in this embodiment, the support layer 3 is disposed between the first electrode layer 2 and the substrate layer 1. This avoids directly forming the first electrode layer 2 on the substrate layer 1; instead, a support layer 3 is first formed on the substrate layer 1, and then the first electrode layer 2 is formed on the support layer 3, such that a support layer 3 is sandwiched between the first electrode layer 2 and the substrate layer 1. The presence of the support layer 3 creates a certain distance between the first electrode layer 2 and the substrate layer 1, the distance of which depends on the thickness of the support layer 3.

[0035] This invention sandwiches a support layer 3 between the first electrode layer 2 and the substrate layer 1, preventing direct contact between them and maintaining a certain distance, which is the thickness of the support layer 3. The support layer 3 increases the distance between the first electrode layer 2 and the substrate layer 1 from zero. According to capacitor principles, as the distance between the first electrode layer 2 and the substrate layer 1 increases, the capacitance between them decreases, effectively reducing the capacitance-to-capacitance (CP) value. This ensures the effective capacitance output of the microelectromechanical system (MEMS) sensor and improves its sensing accuracy.

[0036] Furthermore, the support layer 3 is disposed between the first electrode layer 2 and the substrate layer 1, thereby forming a suspended gap 4 between the first electrode layer 2 and the substrate layer 1. Figure 1As shown, the support layer 3 does not completely fill the space between the first electrode layer 2 and the substrate layer 1. Instead, the support layer 3 merely creates a certain distance between the first electrode layer 2 and the substrate layer 1, resulting in a suspended space 4. This suspended space 4 can be a large gap formed within the support layer 3 or multiple independent small gaps formed within the support layer 3. The presence of this suspended space 4 creates air between the first electrode layer 2 and the substrate layer 1. Utilizing the lower dielectric constant ε of air, the capacitance between the first electrode layer 2 and the substrate layer 1 is reduced, thereby effectively lowering the capacitance (CP) value between them. This ensures the effective capacitance output of the microelectromechanical system (MEMS) sensor and improves its sensing accuracy.

[0037] This invention establishes a suspended gap 4 between the first electrode layer 2 and the substrate layer 1 by placing the support layer 3 between them. This increases the distance between the first electrode layer 2 and the substrate layer 1 while also creating air between them. Air has a low dielectric constant ε. This reduces the capacitance between the first electrode layer 2 and the substrate layer 1, effectively lowering the capacitance coefficient (CP) between them, ensuring the effective capacitance output of the microelectromechanical system (MEMS) sensor, and improving the sensing accuracy of the MEMS sensor.

[0038] Optionally, the thickness of the support layer 3 ranges from 1 to 20 micrometers.

[0039] like Figure 1 As shown, the thickness of the support layer 3 is the distance between the first electrode layer 2 and the substrate layer 1. During processing, a portion of the support layer 3 needs to be removed to form a cantilever gap 4. In this embodiment, the thickness of the support layer 3 can be selected to be in the range of 1 to 20 micrometers. Within this thickness range, a certain distance exists between the first electrode layer 2 and the substrate layer 1, reducing the capacitance between them, thereby effectively reducing the CP value and increasing the output of the effective capacitance of the microelectromechanical system sensor. At the same time, the thickness of the support layer 3 should be avoided to prevent stress deformation.

[0040] Preferably, the thickness of the support layer 3 is in the range of 5 to 10 micrometers. A thickness of 5 to 10 micrometers for the support layer 3 ensures sufficient distance between the first electrode layer 2 and the substrate layer 1, significantly reducing the capacitance between them. Furthermore, it avoids the increase in the size of the microelectromechanical system sensor caused by an excessively thick support layer 3.

[0041] Optionally, the support layer 3 is a silicon oxide layer or a silicon nitride layer.

[0042] In this embodiment, the support layer 3 is a silicon oxide layer or a silicon nitride layer. That is, the material of the support layer 3 can be silicon oxide, silicon nitride, or other materials commonly used by those skilled in the art. For example, the material of the support layer 3 can be silicon oxide. Silicon oxide has insulating properties, and using silicon oxide to fabricate the support layer 3 can isolate the first electrode layer 2 and the substrate layer 1, preventing the first electrode layer 2 from separating from the substrate layer 1. At the same time, silicon oxide is low in cost and easy to remove, improving the ease of fabrication of the microelectromechanical system sensor.

[0043] Optionally, the second electrode layer 5 is provided with a vent hole 51, which is opposite to the suspension gap 4.

[0044] like Figure 1 As shown, the second electrode layer 5 has a vent 51, which connects the outside air to the gap below the second electrode layer 5, creating an air gap between the second electrode layer 5 and the first electrode layer 2. The vent 51 is positioned opposite the suspended space 4, allowing outside air to enter the suspended space 4 through the vent 51, meaning the suspended space 4 is also filled with air. Since air has a low dielectric constant ε, it reduces the capacitance between the first electrode layer 2 and the substrate layer 1, effectively lowering the capacitance-to-capacitance (CP) value between them. This increases the overall effective capacitance output of the sensor and improves the sensing accuracy of the microelectromechanical system (MEMS) sensor.

[0045] In one embodiment, there can be multiple vent holes, opposite to multiple suspended gaps 4. The second electrode layer 5 has multiple independent vent holes 51, and the support layer 3 has multiple independent suspended gaps 4, with the multiple vent holes 51 opposite to the multiple suspended gaps 4. This allows outside air to uniformly enter the multiple suspended gaps 4 through the multiple vent holes 51, reducing the dielectric constant ε between the first electrode layer 2 and the substrate layer 1, effectively lowering the CP value between the first electrode layer 2 and the substrate layer 1, and increasing the output of the effective capacitance of the microelectromechanical system sensor.

[0046] Optionally, the second electrode layer 5 includes a first mass block 52, a second mass block 53, and a support portion 54. The support portion 54 abuts against the first electrode layer 2. The first mass block 52 and the second mass block 53 are connected to both sides of the support portion 54. The mass of the first mass block 52 is greater than the mass of the second mass block 53.

[0047] like Figure 1As shown, the second electrode layer 5 includes a first mass block 52, a second mass block 53, and a support portion 54 located between the first mass block 52 and the second mass block 53. The support portion 54 abuts against the first electrode layer 2, that is, the lower part of the support portion 54 contacts the upper part of the first electrode layer 2.

[0048] The first mass block 52 and the second mass block 53 are connected to both sides of the support portion 54, with the mass of the first mass block 52 being greater than the mass of the second mass block 53. Alternatively, the mass of the first mass block 52 can be less than the mass of the second mass block 53, as long as the masses of the first mass block 52 and the second mass block 53 are unequal, so that the first mass block 52, the second mass block 53, and the intermediate support portion 54 form a "seesaw" structure. The first mass block 52 and the second mass block 53 can be designed to be made of the same material but have different volumes to achieve different masses, or they can be designed to be made of different materials while having the same volume to achieve different masses.

[0049] In this embodiment, see Figure 1 The mass of the first mass block 52 is greater than the mass of the second mass block 53. When the microelectromechanical system (MEMS) sensor moves upward, due to inertia, the first mass block 52 moves downward and the second mass block 53 moves upward, thus changing the distance between the first mass block 52 and the second mass block 53 and the first electrode layer 2, respectively. When the MEMS sensor moves downward, due to inertia, the first mass block 52 moves upward and the second mass block 53 moves downward, similarly changing the distance between the first mass block 52 and the second mass block 53 and the first electrode layer 2, respectively.

[0050] In this embodiment, by setting the masses of the first mass block 52 and the second mass block 53 to be different, the microelectromechanical system (MEMS) sensor, when moving vertically, will cause the first mass block 52 and the second mass block 53 to move in opposite directions due to inertial forces. Consequently, the first mass block 52 and the first electrode layer 2 form one set of capacitor structures, and the second mass block 53 and the first electrode layer 2 form another set of capacitor structures. These two sets of capacitor structures constitute a differential capacitor structure, improving the testing accuracy of the MEMS sensor.

[0051] The second electrode layer 5 includes a first mass block 52, a second mass block 53, and a support portion 54 located between the first mass block 52 and the second mass block 53. The first mass block 52, the second mass block 53, and the support portion 54 can be designed as a single unit, forming an integral mass block. In this case, the first mass block 52 can be the left portion of the integral mass block, and the second mass block 53 can be the right portion, with the left and right portions having different masses to form a "seesaw" structure.

[0052] Optionally, the microelectromechanical system sensor further includes a cover plate 6, which is disposed on the side of the second electrode layer 5 away from the substrate layer 1, and the cover plate 6 and the second electrode layer 5 form a vacuum chamber.

[0053] like Figure 1 As shown, the cover plate 6 is located on the side of the second electrode layer 5 away from the substrate layer 1, that is, the cover plate 6 is located above the second electrode layer 5. The cover plate 6 is manufactured by a bonding process and forms a vacuum chamber with the second electrode layer 5. On the one hand, the cover plate 6 can protect the electrode layer inside the microelectromechanical system sensor and avoid the influence of external impacts on the internal electrode layer; on the other hand, the formation of the vacuum chamber also provides space for the first mass block 52 and the second mass block 53 to move in opposite directions under the action of inertial force.

[0054] Optionally, the microelectromechanical system (MEMS) sensor is an accelerometer and a microphone.

[0055] In this embodiment, the microelectromechanical system (MEMS) sensor can be an accelerometer, such as a voice accelerometer. Voice accelerometers typically employ capacitive accelerometers, falling under the category of inertial sensors. The voice accelerometer collects skeletal vibration signals during vocalization. It gathers these vibration signals by monitoring the distance changes between the first mass block 52 and the second mass block 53 within the chip, corresponding to the first electrode layer 2. This changes the capacitance value of the voice accelerometer, which, combined with signals from other sensors, improves voice call performance. Furthermore, the vibration frequency of the voice accelerometer is much lower than its natural frequency, resulting in a good linear relationship between its input and output, making it less prone to damage and extending its lifespan. Voice accelerometers are widely used in headphones, AR, VR, and other fields.

[0056] Furthermore, this voice accelerometer can be used for single-axis Z-axis detection, which can improve the sensitivity of the accelerometer and reduce the assembly difficulty of electronic devices that use this voice accelerometer.

[0057] Optionally, the microelectromechanical system sensor provided in this solution can be fabricated using semiconductor vapor deposition. Its fabrication methods mainly include:

[0058] Step 1: Fabricate substrate 1;

[0059] The second step is to deposit a support layer 3 on the substrate layer 1;

[0060] The third step is to deposit the first electrode layer 2 on the support layer 3;

[0061] The fourth step is to deposit the second electrode layer 5.

[0062] The preparation method described above is explained in detail below:

[0063] First, using silicon as substrate 1, a layer of silicon oxide or silicon nitride is deposited on substrate 1, and a support layer 3 is obtained by selectively masking and etching.

[0064] Second, polycrystalline silicon is deposited, doped, and annealed to obtain the first electrode layer 2.

[0065] Third, a sacrificial layer is deposited on the first electrode layer 2. This sacrificial layer can be silicon oxide, silicon nitride, or other materials deposited at low temperatures. Furthermore, grooves are etched into the sacrificial layer to facilitate further material deposition.

[0066] Fourth, a polycrystalline silicon layer is deposited on the sacrificial layer to form the second electrode layer 5, and effective circuit connection is achieved through doping.

[0067] Fifth, grooves are further etched on the second electrode layer 5, and materials such as chromium-nickel-aluminum are deposited as solder joints. Optionally, two solder joints can be provided above the second electrode layer 5, which are used to form electrical connections with the first electrode layer 2 and the second electrode layer 5, respectively. In other embodiments, more solder joints can be deposited to connect to different areas of the first electrode layer 2 or the second electrode layer 5.

[0068] Sixth, the bottom sacrificial layer is released to suspend part of the second electrode layer 5.

[0069] Seventh, according to the specific structural design, remove part of the silicon oxide or silicon nitride material of the support layer 3 to form a suspended space gap 4.

[0070] Eighth, a cover plate is obtained from the deposition.

[0071] The removal of part of the material in the support layer 3 can be carried out by selecting the appropriate material based on the specific material selection of the support layer 3.

[0072] In another embodiment, the microelectromechanical system sensor can be a microphone or other sensor designed to reduce the coupling capacitance requirements between the substrate and the substrate.

[0073] Microelectromechanical systems (MEMS) microphones are microphones manufactured using MEMS technology. Simply put, MEMS microphones utilize semiconductor materials to form capacitors, which are then integrated onto a microcrystalline silicon wafer. MEMS microphones, fabricated using MEMS processes, are characterized by their small size, high sensitivity, and excellent suppression of radio frequency interference (RFI) and electromagnetic interference (EMI). MEMS microphones are commonly used in mid-to-high-end mobile phones and other electronic devices.

[0074] Optionally, the microelectromechanical system sensor is a microphone, the first electrode layer 2 is a back electrode plate, and the second electrode layer 5 is a diaphragm.

[0075] like Figure 2 As shown, when the microelectromechanical system (MEMS) sensor is a microphone, the first electrode layer 2 is a back electrode plate, the second electrode layer 5 is a diaphragm, and the support layer 3 is disposed between the first electrode layer 2 and the substrate layer 1, forming a suspended space gap 4 between the first electrode layer 2 and the substrate layer 1. The suspended space gap 4 is opposite to the vent hole 51 on the diaphragm, so that the suspended space gap 4 is filled with air. This increases the distance between the back electrode plate and the substrate layer 1, while also reducing the dielectric constant ε, thus reducing the capacitance. This effectively lowers the CP value between the back electrode plate and the substrate layer 1, increases the output of the microphone's effective capacitance, and improves the microphone's testing accuracy and overall acoustic performance.

[0076] In the microphone of this embodiment, when sound pressure is applied to the diaphragm, the diaphragm vibrates to change the capacitance between the diaphragm and the back plate, thereby changing the output voltage of the capacitor, so that the microphone converts the sound signal into an electrical signal.

[0077] The present invention also provides an electronic device. This electronic device includes a microelectromechanical system (MEMS) sensor as described in any one of the preceding claims. The electronic device using the aforementioned MEMS sensor is capable of converting sound signals into electrical signals.

[0078] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0079] While specific embodiments of the invention 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 the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A microelectromechanical system (MEMS) sensor, characterized in that, include: Substrate layer (1) and first electrode layer (2); A support layer (3) is disposed between the first electrode layer (2) and the substrate layer (1) to form a suspended gap (4) between the first electrode layer (2) and the substrate layer (1); The second electrode layer (5) is disposed on the side of the first electrode layer (2) away from the substrate layer (1) and opposite to the first electrode layer (2); The second electrode layer (5) includes a first mass block (52), a second mass block (53) and a support portion (54). The support portion (54) abuts against the first electrode layer (2). The first mass block (52) and the second mass block (53) are connected to both sides of the support portion (54). The mass of the first mass block (52) is greater than the mass of the second mass block (53). The suspended space gap (4) is formed by directional removal of part of the support layer (3).

2. A microelectromechanical system sensor according to claim 1, characterized in that, The thickness of the support layer (3) ranges from 1 to 20 micrometers.

3. A microelectromechanical system sensor according to claim 1, characterized in that, The thickness of the support layer (3) ranges from 5 to 10 micrometers.

4. A microelectromechanical system sensor according to claim 1, characterized in that, The support layer (3) is a silicon oxide layer or a silicon nitride layer.

5. A microelectromechanical system sensor according to claim 1, characterized in that, The second electrode layer (5) has a vent hole (51) and the suspension gap (4) are opposite each other.

6. A microelectromechanical system sensor according to claim 1, characterized in that, It also includes a cover plate (6), which is disposed on the side of the second electrode layer (5) away from the substrate layer (1), and the cover plate (6) and the second electrode layer (5) form a vacuum chamber.

7. A microelectromechanical system sensor according to claim 1, characterized in that, The microelectromechanical system sensors are an accelerometer and a microphone.

8. A microelectromechanical system sensor according to claim 1, characterized in that, The microelectromechanical system sensor is a microphone, the first electrode layer (2) is a back electrode plate, and the second electrode layer (5) is a diaphragm.

9. An electronic device, characterized in that, The sensor includes any one of claims 1 to 8.

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