CN115243170A - Micro electro mechanical system sensor and electronic equipment - Google Patents

Abstract

The embodiments of the present disclosure disclose a MEMS sensor and an electronic device. The MEMS sensor includes a substrate layer, a first electrode layer and a support layer, and the support layer is arranged between the first electrode layer and the substrate layer, so that the first electrode layer and the substrate A suspended gap is formed between the bottom layers. A technical effect of the embodiments of the present disclosure is that, by arranging the support layer between the first electrode layer and the substrate layer, a suspension gap is formed. 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

A MEMS sensor and electronic equipment

technical field

The present invention relates to the technical field of micro-electromechanical systems (MEMS), and more particularly, the present invention relates to a MEMS sensor and an electronic device.

Background technique

The existing voice acceleration sensor usually has an excessive CP (coupling capacitance) value, and the effective signal is affected by the excessive CP and the accuracy is low, which greatly interferes with signal processing and cannot achieve high-definition headphones in a noisy environment. Pickup and noise reduction.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a novel MEMS sensor and electronic device, aiming to solve at least one problem in the prior art.

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

a substrate layer and a first electrode layer;

a support layer, the support layer is disposed between the first electrode layer and the substrate layer, so that a suspension gap is formed between the first electrode layer and the substrate layer;

A second electrode layer, the second electrode layer is disposed on the side of the first electrode layer away from the substrate layer and is opposite to the first electrode layer.

Optionally, the thickness of the support layer ranges from 1 to 20 microns.

Optionally, the thickness of the support layer ranges from 5 to 10 microns.

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

Optionally, the second electrode layer is provided with a ventilation hole, and the ventilation hole is opposite to the suspension gap.

Optionally, the second electrode layer includes a first mass block, a second mass mass and a support part, the support part is in contact with the first electrode layer, the first mass block and the second mass block Connected to both sides of the support portion, the mass of the first mass is greater than the mass of the second mass.

Optionally, the MEMS sensor further includes a cover plate, the cover plate is disposed on the side of the second electrode layer away from the substrate layer, and the cover plate and the second electrode layer form a vacuum chamber .

Optionally, the MEMS sensor is an acceleration sensor and a microphone.

Optionally, the MEMS sensor is a microphone, the first electrode layer is a back plate, and the second electrode layer is a diaphragm.

According to another aspect of the present invention, an electronic device is provided. The electronic device includes the MEMS sensor described in any one of the above.

A technical effect of the embodiments of the present disclosure is that, by arranging the support layer between the first electrode layer and the substrate layer, a suspension gap is formed between the first electrode layer and the substrate layer. While increasing the distance between the first electrode layer and the substrate layer, the dielectric constant ε between the first electrode layer and the substrate layer is also reduced, thereby improving the MEMS The test accuracy of the sensor.

Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings.

Description of drawings

The accompanying drawings, which form a part of the specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

FIG. 1 is a schematic structural diagram of a MEMS sensor according to an embodiment of the present disclosure;

FIG. 2 is a schematic structural diagram of a MEMS microphone according to an embodiment of the present disclosure.

Description of reference numbers:

1. Substrate layer; 2. First electrode layer; 3. Support layer; 4. Suspended gap; 5. Second electrode layer; Support part; 6. Cover plate.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques and devices should be considered part of the specification.

In all examples shown and discussed herein, any specific values should be construed as illustrative only and not limiting. Accordingly, other instances of the exemplary embodiment may have different values.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further discussion in subsequent figures.

The invention provides a micro-electromechanical system sensor. MEMS sensor is a new type of sensor manufactured by using microelectronics and micromachining technology. Compared with traditional sensors, it has the characteristics of small size, light weight, low cost, low power consumption, high reliability, suitable for mass production, easy integration and intelligent realization. MEMS sensors are commonly used in medical, automotive, electronic products and other fields.

As shown in FIG. 1 , the MEMS sensor provided by the present 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 , so that a suspension gap 4 is formed 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 is opposite to the first electrode layer 2. The first electrode layer 2 and the second electrode layer 5 to form a gap.

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

Capacitive sensors use various types of capacitors as sensing elements to convert the measured physical or mechanical quantities into a conversion device for changes in capacitance. In fact, it is a capacitor with variable parameters. Capacitive sensors are widely used in the measurement of displacement, angle, vibration, speed, pressure, composition analysis, medium properties, etc.

Capacitive sensors will generate CP (coupling capacitance) during operation. CP is mainly caused by the capacitor effect formed between the lower electrode and the substrate. The coupling capacitance will seriously interfere with the output of the effective capacitance, greatly reducing and interfering with the overall acoustics of the sensor. performance. The larger the CP value, the weaker the effective signal of the sensor. Due to the limitation of the capacitive sensor structure, CP cannot be fundamentally eliminated, and the CP value 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 plate capacitor, the capacitance C=ε*ε ₀ *S/d, that is, the capacitance C is proportional to the dielectric constant ε of the medium and inversely proportional to the distance d between the two plates. Therefore, the capacitance C can be reduced by reducing the dielectric constant ε or increasing the distance d between the two polar plates, thereby reducing the CP value, relatively improving the effective signal, and improving the accuracy of the sensor.

As shown in FIG. 1 , in this embodiment of the present disclosure, the support layer 3 is disposed between the first electrode layer 2 and the substrate layer 1 . Instead of directly forming the first electrode layer 2 on the substrate layer 1 , a layer of the support layer 3 is first formed on the substrate layer 1 , and then the first electrode is formed on the support layer 3 layer 2 , so that a layer of the support layer 3 is sandwiched between the first electrode layer 2 and the substrate layer 1 . The existence of the support layer 3 causes a certain distance between the first electrode layer 2 and the substrate layer 1 , and the distance depends on the thickness of the support layer 3 .

In the present invention, the support layer 3 is sandwiched between the first electrode layer 2 and the substrate layer 1 , so that there is no direct contact between the first electrode layer 2 and the substrate layer 1 , but there is A certain distance, the distance is the thickness of the support layer 3 . The arrangement of the support layer 3 makes the distance between the first electrode layer 2 and the substrate layer 1 from nothing to exist. According to the principle of capacitors, when the distance between the first electrode layer 2 and the substrate layer 1 increases from zero, the capacitance between the first electrode layer 2 and the substrate layer 1 will decrease. Furthermore, the CP value between the first electrode layer 2 and the substrate layer 1 can be effectively reduced, the output of the effective capacitance of the MEMS sensor can be ensured, and the sensing accuracy of the MEMS sensor can be improved.

In addition, the support layer 3 is disposed between the first electrode layer 2 and the substrate layer 1 , so that a suspension gap 4 is formed between the first electrode layer 2 and the substrate layer 1 . As shown in FIG. 1 , the supporting layer 3 is not completely filled between the first electrode layer 2 and the substrate layer 1 , but only the supporting layer 3 is used to make the first electrode layer 2 and the There is a certain distance between the substrate layers 1, and a suspended gap 4 exists between the first electrode layer 2 and the substrate layer 1. The suspended gap 4 may be a large gap formed in the support layer 3, or it may be A plurality of independent small gaps formed in the support layer 3 . The existence of the dangling gap 4 causes air to exist between the first electrode layer 2 and the substrate layer 1 , and the first electrode layer 2 and the substrate layer are formed by utilizing the relatively small dielectric constant ε of air. The capacitance between 1 is reduced, which can effectively reduce the CP value between the first electrode layer 2 and the substrate layer 1, ensure the output of the effective capacitance of the MEMS sensor, and improve the MEMS sensor. sensing accuracy.

In the present invention, the support layer 3 is disposed between the first electrode layer 2 and the substrate layer 1 , so that a suspension gap 4 is formed between the first electrode layer 2 and the substrate layer 1 . While increasing the distance between the first electrode layer 2 and the substrate layer 1, there is also air between the first electrode layer 2 and the substrate layer 1, and the air has a smaller dielectric dielectric constant ε. Therefore, the capacitance between the first electrode layer 2 and the substrate layer 1 is reduced, the CP value between the first electrode layer 2 and the substrate layer 1 is effectively reduced, and the MEMS is ensured. The output of the effective capacitance of the sensor improves the sensing accuracy of the MEMS sensor.

Optionally, the thickness of the support layer 3 ranges from 1 to 20 microns.

As shown in FIG. 1 , the thickness of the support layer 3 is the distance between the first electrode layer 2 and the substrate layer 1 , and a part of the support layer 3 needs to be removed during processing to form a suspended gap 4 . In this embodiment, the thickness of the support layer 3 can be selected in the range of 1 to 20 microns. Within this thickness range, a certain distance can exist between the first electrode layer 2 and the substrate layer 1 , thereby reducing the capacitance between the first electrode layer 2 and the substrate layer 1 , thereby reducing the capacitance between the first electrode layer 2 and the substrate layer 1 . The CP value is effectively reduced, and the output of the effective capacitance of the MEMS sensor is increased; at the same time, excessive thickness of the support layer 3 should be avoided to avoid stress deformation.

Wherein, preferably, the thickness of the support layer 3 ranges from 5 to 10 microns. The thickness of the support layer 3 of 5 to 10 microns can make a sufficient distance between the first electrode layer 2 and the substrate layer 1, and significantly reduce the gap between the first electrode layer 2 and the substrate layer 1. capacitance between. In addition, the increase in the size of the MEMS sensor caused by the excessively thick support layer 3 is also avoided.

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

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 may be silicon oxide material, silicon nitride material or other materials commonly used by those skilled in the art. For example, the material of the support layer 3 can be silicon oxide, which has insulating properties. Using silicon oxide to make the support layer 3 can isolate the first electrode layer 2 and the substrate layer 1, and avoid the first electrode layer 2 and all The substrate layer 1 is described. At the same time, the cost of silicon oxide is low, and it is easy to remove, which improves the simplicity of processing the MEMS sensor.

Optionally, the second electrode layer 5 is provided with a ventilation hole 51 , and the ventilation hole 51 is opposite to the suspension gap 4 .

As shown in FIG. 1 , the second electrode layer 5 has a ventilation hole 51 , and the ventilation hole 51 can communicate with the outside air and the gap under the second electrode layer 5 , so that the second electrode layer 5 and the Air gaps are formed between the first electrode layers 2 . The ventilation holes 51 are arranged opposite to the suspension gap 4 , so that outside air can enter the suspension gap 4 through the ventilation holes 51 , that is, the suspension gap 4 is also filled with air. Since the dielectric constant ε of air is small, the capacitance between the first electrode layer 2 and the substrate layer 1 can be reduced, thereby effectively reducing the gap between the first electrode layer 2 and the substrate layer 1 Therefore, the output of the effective capacitance of the entire sensor is increased, and the sensing accuracy of the MEMS sensor is improved.

In one embodiment, there may be a plurality of ventilation holes opposite to the plurality of air gaps 4 . The second electrode layer 5 has a plurality of independent air holes 51 , the support layer 3 has a plurality of independent air gaps 4 , and the air holes 51 are opposite to the plurality of air gaps 4 . The outside air can evenly enter the plurality of the suspension gaps 4 through the plurality of the ventilation holes 51, the dielectric constant ε between the first electrode layer 2 and the substrate layer 1 can be reduced, and the The CP value between the first electrode layer 2 and the substrate layer 1 increases the output of the effective capacitance of the MEMS sensor.

Optionally, the second electrode layer 5 includes a first mass 52 , a second mass 53 and a supporting portion 54 , the supporting portion 54 is in contact with the first electrode layer 2 , and the first mass 52 The second mass 53 is connected to both sides of the support portion 54 , and the mass of the first mass 52 is greater than that of the second mass 53 .

As shown in FIG. 1 , the second electrode layer 5 includes a first mass 52 , a second mass 53 and a support portion 54 located between the first mass 52 and the second mass 53 . The support portion 54 is in contact with the first electrode layer 2 , that is, the lower portion of the support portion 54 is in contact with the upper portion of the first electrode layer 2 .

The first mass 52 and the second mass 53 are connected to two sides of the support portion 54 , and the mass of the first mass 52 is greater than that of the second mass 53 . Of course, the mass of the first mass block 52 can also be smaller than the mass of the second mass block 53, as long as the mass of the first mass block 52 and the second mass block 53 are not equal, so that all the The first mass block 52, the second mass block 53 and the middle support portion 54 form a "teeter-totter" structure. Wherein, the first mass block 52 and the second mass block 53 can be designed to use the same material but have different volumes so that the quality of the two is different, and the first mass block 52 and the second mass block 53 can also be designed When the mass blocks 53 are the same in volume, they are respectively formed of different materials so that the two have different masses.

In this embodiment, referring to FIG. 1 , the mass of the first mass 52 is greater than the mass of the second mass 53 . When the MEMS sensor moves upward, due to the existence of inertial force, the first mass block 52 moves downward and the second mass block 53 moves upward, which changes the first mass respectively. 52 and the distance between the second mass 53 and the first electrode layer 2 . When the MEMS sensor moves downward, due to the existence of inertial force, the first mass 52 moves upward and the second mass 53 moves downward, which also changes the first mass respectively. 52 and the distance between the second mass 53 and the first electrode layer 2 .

In this embodiment, by setting the masses of the first mass block 52 and the second mass block 53 to be different, when the MEMS sensor generates vertical movement, due to the existence of inertial force, the first mass The mass 52 and the second mass 53 can move in opposite directions. Further, the first mass block 52 and the first electrode layer 2 form a set of capacitance structures, the second mass block 53 and the first electrode layer 2 form another set of capacitance structures, and the two sets of capacitance structures constitute a differential The capacitive structure improves the test accuracy of the MEMS sensor.

The second electrode layer 5 includes a first mass 52 , a second mass 53 , and a support portion 54 located between the first mass 52 and the second mass 53 . Wherein, the first mass block 52, the second mass block 53 and the support portion 54 may be designed as a whole, and the three together form an integral mass block. At this time, the first mass 52 can be the left part of the whole mass, and the second mass 53 can be the right part of the whole mass, and the left part and the right part have different masses to form a "teeter-totter" structure.

Optionally, the MEMS sensor further includes a cover plate 6 , the cover plate 6 is disposed on the side of the second electrode layer 5 away from the substrate layer 1 , and the cover plate 6 is connected to the second electrode layer 1 . Layer 5 forms a vacuum chamber.

As shown in FIG. 1 , 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 made 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 MEMS sensor and avoid the impact of external impact on the internal electrode layer; on the other hand, the formation of the vacuum chamber also provides the first mass 52 And the second mass 53 can reversely move under the action of inertial force to provide a movement space.

Optionally, the MEMS sensor is an acceleration sensor and a microphone.

In this embodiment, the MEMS sensor may be an acceleration sensor, such as a voice acceleration sensor. Voice acceleration sensors usually use capacitive acceleration sensors, which belong to the range of inertial sensors. The voice acceleration sensor can collect the bone vibration signal of the human body when the sound is produced, and the vibration is collected by the first mass 52 and the second mass 53 in the chip corresponding to the distance changes between the first electrode layers 2 respectively. Signals to change the capacitance value of the voice acceleration sensor, combined with other sensor signals, can improve the effect of functions such as voice calls after processing. In addition, the vibration frequency of the voice acceleration sensor is much lower than its natural frequency, so that there is a good linear relationship between its input and output, and it is not easy to be damaged and has a long service life. Voice accelerometers are mostly used in headsets, AR, VR and other fields.

In addition, the voice acceleration sensor can be used for Z-axis single-axis detection, which can improve the sensitivity of the acceleration sensor and reduce the assembly difficulty of an electronic device applying the voice acceleration sensor.

Optionally, the MEMS sensor provided by this solution can be fabricated by using a semiconductor vapor deposition method. Its preparation method mainly includes:

The first step is to make the substrate layer 1;

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

The third step, depositing the first electrode layer 2 on the support layer 3;

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

The above-mentioned preparation method is described in detail below:

First, using silicon as the substrate layer 1 , depositing a layer of silicon oxide or silicon nitride on the substrate layer 1 , and selectively masking and etching the supporting layer 3 .

Second, polysilicon is deposited, doped and annealed to obtain the first electrode layer 2 .

Third, a sacrificial layer is deposited on the first electrode layer 2, and these sacrificial layers may be silicon oxide, silicon nitride, etc. deposited at a low temperature. Also, grooves are etched on the sacrificial layer to further deposit materials.

Fourth, a polysilicon layer is deposited on the sacrificial layer to form the second electrode layer 5, and effective circuit connection is achieved by doping.

Fifth, grooves are further etched on the second electrode layer 5 and materials such as CrNiAl are deposited as solder joints. Optionally, two welding points may be disposed above the second electrode layer 5 , and the two welding points are respectively used to form electrical connections with the first electrode layer 2 and the second electrode layer 5 . In other embodiments, more solder joints may also be deposited for connection to different regions of the first electrode layer 2 or the second electrode layer 5 .

Sixth, the bottom sacrificial layer is released, so that the second electrode layer 5 is partially suspended.

Seventh, according to the specific structural design, part of the silicon oxide or silicon nitride material of the support layer 3 is removed to form the suspended gap 4 .

Eighth, a cover plate is obtained by deposition.

Wherein, for the removal of part of the material of the support layer 3 , the corresponding material may be selected for removal according to the specific material selection of the support layer 3 .

In another embodiment, the MEMS sensor may be a microphone or other sensor designed to reduce the coupling capacitance requirement between the substrate and the substrate.

Micro-Electro-Mechanical Systems (MEMS) microphones are microphones based on MEMS technology. Simply put, MEMS microphones use semiconductor materials to form capacitors and integrate the capacitors on micro-silicon wafers. The microelectromechanical microphone formed by the microelectromechanical process has the characteristics of small size and high sensitivity, and the microelectromechanical microphone has good radio frequency interference (RFI) and electromagnetic interference (EMI) suppression capability. MEMS microphones are often used in electronic devices such as mid-to-high-end mobile phones.

Optionally, the MEMS sensor is a microphone, the first electrode layer 2 is a back plate, and the second electrode layer 5 is a diaphragm.

As shown in FIG. 2 , when the MEMS sensor is a microphone, the first electrode layer 2 is a back plate, the second electrode layer 5 is a diaphragm, and the support layer 3 is disposed on the first electrode. A suspended gap 4 is formed between an electrode layer 2 and the substrate layer 1 , and between the first electrode layer 2 and the substrate layer 1 . The suspension gap 4 is opposite to the ventilation hole 51 on the diaphragm, so that the suspension gap 4 is filled with air. Further, while increasing the distance between the back plate and the substrate layer 1, the dielectric constant ε is also reduced, so that the capacitance is reduced, and the distance between the back plate and the substrate layer 1 can be effectively reduced. The CP value increases the output of the effective capacitance of the microphone, and improves the test accuracy and overall acoustic performance of the microphone.

In the microphone of this embodiment, when the sound pressure acts on the diaphragm, the diaphragm will vibrate accordingly, so as 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 for electrical signals.

The present invention also provides an electronic device. The electronic device includes the MEMS sensor described in any one of the above. The electronic device applying the above-mentioned MEMS sensor can convert sound signals into electrical signals.

The above embodiments focus on 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. Repeat.

While some specific embodiments of the present invention have been described in detail by way of example, those skilled in the art will appreciate that the above examples are provided for illustration only and not for the purpose of limiting the scope of the invention. Those skilled in the art will appreciate that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the invention is defined by the appended claims.

Claims (10)

1. a microelectromechanical system sensor, is characterized in that, comprises: a substrate layer (1) and a first electrode layer (2); a support layer (3), the support layer (3) being arranged between the first electrode layer (2) and the substrate layer (1), so that the first electrode layer (2) and the substrate A suspended gap (4) is formed between the bottom layers (1); A second electrode layer (5), the second electrode layer (5) is provided on the side of the first electrode layer (2) away from the substrate layer (1) and is connected to the first electrode layer (2) relatively. 2 . The MEMS sensor according to claim 1 , wherein the thickness of the support layer ( 3 ) ranges from 1 to 20 μm. 3 . 3 . The MEMS sensor according to claim 1 , wherein the thickness of the support layer ( 3 ) ranges from 5 to 10 μm. 4 . 4 . The MEMS sensor according to claim 1 , wherein the support layer ( 3 ) is a silicon oxide layer or a silicon nitride layer. 5 . 5 . The MEMS sensor according to claim 1 , wherein the second electrode layer ( 5 ) is provided with a ventilation hole ( 51 ), the ventilation hole ( 51 ) and the suspended gap ( 5 . 4) Relative. 6. The MEMS sensor according to claim 1, wherein the second electrode layer (5) comprises a first mass (52), a second mass (53) and a support portion (54) ), the support portion 54 is in contact with the first electrode layer (2), and 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). 7 . The MEMS sensor according to claim 1 , further comprising a cover plate ( 6 ), and the cover plate ( 6 ) is disposed on the second electrode layer ( 5 ) away from the lining. 8 . On one side of the bottom layer (1), the cover plate (6) and the second electrode layer (5) form a vacuum chamber. 8 . The MEMS sensor according to claim 1 , wherein the MEMS sensor is an acceleration sensor and a microphone. 9 . 9. The MEMS sensor according to claim 1, wherein the MEMS sensor is a microphone, the first electrode layer (2) is a back plate, and the second electrode layer ( 5) is the diaphragm. 10. An electronic device, characterized in that it comprises the MEMS sensor according to any one of claims 1 to 9.

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