MEMS chip, manufacturing method of MEMS chip, sensor and electronic equipment

Abstract

The invention discloses an MEMS chip, a manufacturing method of the MEMS chip, a sensor and electronic equipment, and relates to the technical field of MEMS chips, the MEMS chip comprises a substrate layer, a buffer layer, an insulation layer, an isolation layer and a movable pole plate layer which are sequentially stacked, the insulation layer is provided with a containing groove, a fixed pole plate layer is arranged in the containing groove, and the fixed pole plate layer is provided with a plurality of through holes; the isolating layer is provided with through holes corresponding to at least part of the fixed polar plate layer, so that the fixed polar plate layer and the movable polar plate layer are oppositely arranged and spaced; the buffer layer comprises a plurality of buffer columns which are arranged at intervals, each buffer column comprises a bottom and a top which are oppositely arranged, the bottoms abut against the substrate layer, the tops abut against the insulating layer, and a gap is formed between any two adjacent buffer columns. The MEMS chip and the sensor made of the MEMS chip have the advantage of high detection precision.

Description

Technical Field

[0001] This application relates to the field of MEMS chip technology, and in particular to MEMS chips, methods for fabricating MEMS chips, sensors, and electronic devices. Background Technology

[0002] A sensor is a precision miniature device that converts external signals into electrical signals. Its core principle is to utilize changes in external signals that cause displacement of a mechanical structure, thereby altering the capacitance value and converting it into an electrical signal that can be detected. For pressure sensors, this means converting external sound pressure signals into vibrations of the sensitive diaphragm of a MEMS chip, resulting in displacement, a change in capacitance, and ultimately, an electrical signal that can be detected. However, current sensor technologies suffer from low detection accuracy. Summary of the Invention

[0003] The main objective of this application is to propose a MEMS chip, a method for fabricating a MEMS chip, a sensor, and an electronic device, with the aim of at least improving the technical problem of low sensor detection accuracy in related technologies.

[0004] To achieve the above objectives, according to some embodiments of this application, this application provides a MEMS chip, including a substrate layer, a buffer layer, an insulating layer, an isolation layer, and a movable electrode layer stacked sequentially. The insulating layer is provided with a receiving groove, and a fixed electrode layer is disposed within the receiving groove. The isolation layer is provided with through holes corresponding to at least a portion of the fixed electrode layer, so that the fixed electrode layer and the movable electrode layer are disposed facing each other and separated by a gap. The buffer layer includes a plurality of buffer pillars arranged at intervals, each buffer pillar including a bottom and a top disposed opposite to each other. The bottom abuts against the substrate layer, and the top abuts against the insulating layer. A gap is provided between any two adjacent buffer pillars.

[0005] In some embodiments, the thickness direction of the base layer is defined as a first direction, and the buffer pillar is inclined relative to the first direction.

[0006] In some embodiments, a direction perpendicular to the first direction and extending along the surface of the base layer is defined as the second direction, and the angle between the buffer post and the second direction is θ, then: 45°≤θ≤80°.

[0007] In some embodiments, the dimension of the buffer post along the first direction is defined as the length of the buffer post, the dimension of the buffer post along the second direction is defined as the width of the buffer post, and the length-to-width ratio A of the buffer post is length / width, then: 1≤A≤3.

[0008] In some embodiments, the buffer layer further includes a reinforcing member disposed on the base layer and extending toward the buffer post.

[0009] In some embodiments, the reinforcing member includes a bottom surface and an abutting surface connected to the bottom surface. The bottom surface is disposed on the base layer, and the abutting surface is disposed facing the inclined surface of the buffer column. The included angle between the bottom surface and the abutting surface is defined as α, then (θ-α)∈[0°, 10°].

[0010] In some embodiments, the abutting surface is fitted to the inclined surface of the buffer post.

[0011] In some embodiments, a plurality of the buffer pillars are arranged in an array on the base layer.

[0012] According to some embodiments of this application, this application provides a method for fabricating a MEMS chip, including the following steps: Provide a first substrate and a second substrate; An insulating layer, a fixed electrode layer, an isolation layer, and a movable electrode layer are sequentially disposed on the first substrate. A buffer layer is provided on the second substrate, the buffer layer including a plurality of buffer pillars and a gap provided between two adjacent buffer pillars; The buffer layer is bonded to the side of the first substrate opposite to the insulating layer.

[0013] In some embodiments, after the step of sequentially forming an insulating layer, a fixed electrode layer, an isolation layer, and a movable electrode layer on the first substrate, the method further includes the step of: The first substrate is thinned from the side of the first substrate away from the insulating layer.

[0014] In some embodiments, after the step of bonding the buffer layer to the side of the first substrate opposite to the insulating layer, the method further includes the step of: The second substrate is thinned from the side of the second substrate away from the buffer layer.

[0015] According to some embodiments of this application, this application provides a method for fabricating a MEMS chip, including the following steps: A first substrate and a second substrate are provided; the first substrate includes a first side and a second side disposed opposite to each other. An insulating layer is provided on the first side, and a buffer layer is provided on the second side. The buffer layer includes a plurality of buffer pillars and a gap between two adjacent buffer pillars. The second substrate is bonded to the buffer layer; A fixed electrode layer, an isolation layer, and a movable electrode layer are sequentially disposed on the insulating layer.

[0016] In some embodiments, after the step of providing an insulating layer on the first side and before the step of providing a buffer layer on the second side, the method further includes the step of: The first substrate is thinned from the second side.

[0017] In some embodiments, after the step of sequentially distributing the fixed electrode layer, the insulating layer, and the movable electrode layer on the insulating layer, the method further includes the step of: The second substrate is thinned from the side of the second substrate away from the buffer layer.

[0018] According to some embodiments of this application, this application provides a sensor, the sensor including a base plate and a housing covered on the base plate, the base plate and the housing forming a receiving cavity, an ASIC chip and a MEMS chip signal-connected to the ASIC chip are disposed in the receiving cavity, the MEMS chip is the MEMS chip described above, and / or the MEMS chip is fabricated by the MEMS chip fabrication method described above.

[0019] According to some embodiments of this application, this application provides an electronic device that includes the sensor described above.

[0020] In the above scheme, the MEMS chip includes a substrate layer, a buffer layer, an insulating layer, an isolation layer, and a movable electrode layer stacked sequentially. The insulating layer has a receiving groove, within which a fixed electrode layer is disposed. The isolation layer has through holes corresponding to at least a portion of the fixed electrode layer, so that the fixed electrode layer and the movable electrode layer are positioned facing each other and spaced apart. The buffer layer includes multiple buffer pillars arranged at intervals, each buffer pillar having a bottom and a top positioned opposite each other. The bottom abuts against the substrate layer, and the top abuts against the insulating layer. A gap is provided between any two adjacent buffer pillars. This MEMS chip and the sensor made from it have the advantage of high detection accuracy. The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0022] Figure 1This is a schematic diagram of a cross-sectional structure of a MEMS chip. Figure 2 for Figure 1 A schematic diagram of the structure of a MEMS chip under stress. Figure 3 This is a cross-sectional structural diagram of a MEMS chip according to some embodiments of this application; Figure 4 This is a schematic diagram of the buffer layer structure of a MEMS chip in some embodiments of this application; Figure 5 This is a schematic diagram of a portion of the buffer layer structure of a MEMS chip according to some embodiments of this application; Figure 6 This is a schematic diagram of another part of the structure of the buffer layer of a MEMS chip according to some embodiments of this application; Figure 7 This is a schematic flowchart illustrating the method for fabricating a MEMS chip according to the first embodiment of this application. Figure 8 This is a schematic flowchart of a method for fabricating a MEMS chip according to the second embodiment of this application; Figure 9 This is a flowchart illustrating the method for fabricating a MEMS chip according to the third embodiment of this application; Figure 10 This is a detailed schematic diagram illustrating the steps of a MEMS chip fabrication method according to an embodiment of this application. Figure 11 This is a schematic flowchart illustrating the method for fabricating a MEMS chip according to the fourth embodiment of this application. Figure 12 This is a schematic flowchart illustrating the method for fabricating a MEMS chip according to the fifth embodiment of this application. Figure 13 This is a schematic diagram of the structure of a sensor according to some embodiments of this application.

[0023] Explanation of icon numbers: 1000, Sensors; 100. MEMS chip; 200. ASIC chip; 300. Baseboard; 400. Housing; 1. Base layer; 2. Buffer layer; 21. Buffer pillar; 211. Top; 212. Bottom; 213. Inclined surface; 22. Gap; 23. Reinforcing member; 231. Bottom surface; 232. Abutting surface; 3. Insulating layer; 4. Isolation layer; 5. Fixed electrode layer; 6. Movable electrode layer; 7. Spacing; 8. Solder pad; 9. Support layer.

[0024] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0025] The technical solutions in this embodiment will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this embodiment are only used to explain the relative positional relationship and movement of each component in a specific posture (as shown in the attached figure). If the specific posture changes, the directional indicator will also change accordingly.

[0027] Furthermore, the use of terms such as "first," "second," etc., in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0028] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0029] Furthermore, the technical solutions of the various embodiments of this application can be combined with each other, but only if they are feasible to those skilled in the art. If a combination of technical solutions contradicts each other or cannot be implemented, it should be considered that such a combination does not exist and is not within the scope of protection claimed in this application. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0030] The descriptions of directions such as "up", "down", "front", "back", "left", and "right" in this application are based on the directions shown in the accompanying drawings and are only used to explain the relative positional relationships between the components in the posture shown in the figures. If the specific posture changes, the directional indication will also change accordingly.

[0031] A sensor is a precision miniature device that converts external signals into electrical signals. Its core principle is to utilize changes in external signals that cause displacement of a mechanical structure, thereby changing the capacitance value and converting it into an electrical signal that can be detected. However, existing sensors suffer from low detection accuracy.

[0032] After careful research, the applicant discovered that sensors, such as MEMS capacitive barometric pressure sensors, are precision miniature devices that convert barometric pressure signals into electrical signals. Their core principle is to utilize changes in barometric pressure that cause displacement of a mechanical structure, thereby altering the capacitance value. Generally, a sensor consists of a base plate, a housing covering the base plate, and MEMS or ASIC chips.

[0033] MEMS chips typically consist of two parallel, spaced-apart fixed electrode layers and a movable electrode layer, as well as a substrate layer, an insulating layer, and internal circuitry. As the core sensing unit, due to its unique structure, MEMS chips are particularly susceptible to packaging stress caused by mismatches in the thermal expansion coefficients of the bonding materials or substrate layer during assembly, leading to drift in accuracy and linearity.

[0034] Packaging stress originates from two main sources. First, it stems from deformation stress caused by the mismatch in thermal expansion coefficients between the various layers of materials, the substrate, and the adhesive materials within the MEMS chip. When the temperature changes, the different layers expand or contract to varying degrees, creating internal constraints and thus generating stress. Second, residual stress is generated on the MEMS chip during the packaging process, such as dispensing, curing, and molding. This stress may slowly dissipate after the sensor leaves the factory, leading to reading drift.

[0035] Reference Figure 1 and Figure 2 Regardless of the type of stress present, it will affect the MEMS chip, causing the MEMS chip to warp or deform. The slight deformation of its core pressure-sensitive diaphragm or electrodes will directly change the electrode spacing and charge distribution, causing unexpected drift in capacitance value, which seriously affects the detection accuracy and long-term stability of the sensor.

[0036] Therefore, this application provides a MEMS chip.

[0037] Reference Figure 3 and Figure 4According to some embodiments of this application, this application provides a MEMS chip 100, including a base layer 1, a buffer layer 2, an insulating layer 3, an isolation layer 4, and a movable electrode layer 6 stacked sequentially. The insulating layer 3 is provided with a receiving groove, and a fixed electrode layer 5 is provided in the receiving groove. The isolation layer 4 is provided with a through hole corresponding to at least part of the fixed electrode layer 5, so that the fixed electrode layer 5 and the movable electrode layer 6 face each other and form a gap 7. The buffer layer 2 includes a plurality of buffer pillars 21 arranged at the gap 7. Each buffer pillar 21 includes a bottom 212 and a top 211 arranged opposite to each other. The bottom 212 abuts against the base layer 1, and the top 211 abuts against the insulating layer 3. A gap 22 is provided between any two adjacent buffer pillars 21.

[0038] The substrate 1, which is the substrate of the MEMS chip 100, can be a silicon substrate. The buffer layer 2 can be made of materials such as SiO2, SiN4, Al2O3, or polyimide. The insulating layer 3 is disposed on the substrate 1, and a receiving groove can be formed on the insulating layer 3 so that the fixed electrode layer 5 can be installed in the mounting groove. The fixed electrode layer 5 and the movable electrode layer 6 together form the two electrodes of the capacitor. The fixed electrode layer 5 is generally fixed on the insulating layer 3 and will not move significantly. If there is any slight movement, it will move along with the buffer layer 2 and the insulating layer 3. The movable electrode layer 6 can move, that is, it moves along the thickness direction of the movable electrode layer 6. When the external air pressure changes, the movable electrode layer 6 will be displaced. The movement of the movable electrode layer 6 changes the distance 7 between the movable electrode layer 6 and the fixed electrode layer 5, thereby changing the capacitance. The change in capacitance changes the charge of the capacitor, thus converting the external air pressure change signal into an electrical signal output, realizing the detection of air pressure. The isolation layer 4 can be annular with a through-hole in the center. The isolation layer 4, the fixed electrode layer 5, and the movable electrode layer 6 form a cavity. The through-hole also allows the fixed electrode layer 5 and the movable electrode layer 6 to face each other, with a gap 7 between them, enabling capacitance detection. The isolation layer 4 also serves as insulation. Alternatively, a support layer 9 can be deposited around the outer periphery of the movable electrode layer 6, and solder pads 8 can be provided on the support layer 9.

[0039] In the above embodiments of this application, a buffer layer 2 is provided between the base layer 1 and the insulating layer 3. The buffer layer 2 includes a plurality of spaced-apart buffer pillars 21. Each buffer pillar 21 includes a bottom 212 and a top 211 disposed opposite to each other. The bottom 212 abuts against the base layer 1 and may be disposed on the base layer 1. The top 211 abuts against the insulating layer 3. The buffer pillars 21 can provide support. A gap 22 is formed between two adjacent buffer pillars 21. The gap 22 is a blank layer, which may be a vacuum or filled with air. The buffer pillars 21 provide corresponding support performance. The gap 22 between the buffer pillars 21 provides support performance. Figure 2Compared to using a single buffer plate, the overall stiffness is reduced, while the deformation capacity is increased. This allows for better stress absorption through deformation and a stronger ability to isolate stress transmission. It reduces the risk of accuracy or linearity drift in the MEMS chip 100 due to stress, thus improving the detection accuracy of the sensor 1000 and enhancing its temperature stability. In other words, the stress caused by different thermal expansion coefficients or contractions of different layers due to temperature changes can be absorbed by the buffer layer 2, thereby improving temperature stability.

[0040] Reference Figures 3 to 5 In some embodiments, the thickness direction of the base layer 1 is defined as the first direction, and the buffer pillar 21 is inclined relative to the first direction. The thickness direction is the direction perpendicular to the surface of the base layer 1, which is defined here as the first direction. Figure 3 The arrow Z in the diagram indicates the vertical direction. The buffer pillar 21 is inclined relative to the first direction, meaning that the buffer pillar 21 forms an angle with the vertical direction; the buffer pillar 21 is not perpendicular to the substrate layer 1. Specifically, it can be manufactured by patterning a layered buffer plate and then creating multiple inclined buffer pillars 21 with gaps 22 through photolithography processes such as exposure, development, and etching. The inclined buffer pillars 21 provide corresponding support, supporting the insulating layer 3. More importantly, while vertical support pillars can absorb tensile or contractile stress from the vertical direction, they are less effective at absorbing lateral stress, i.e., horizontal stress. In the embodiments of this application, the buffer pillars 21 are set at an angle, which can absorb vertical deformation force through their own compression or stretching, and also absorb horizontal stress through lateral bending. That is, the stress is absorbed and released through the combined deformation of their own compression, stretching and lateral bending. They can absorb horizontal stress, making it difficult for horizontal stress to affect the detection of MEMS chip 100. Furthermore, the deformation capacity of the buffer pillars 21 set at intervals is enhanced, and the stress absorption capacity is enhanced, which is conducive to further improving the detection accuracy and stability of sensor 1000.

[0041] Reference Figure 5 In some embodiments, the direction perpendicular to the first direction and extending along the surface of the base layer 1 is defined as the second direction, and the angle between the buffer pillar 21 and the second direction is θ, then: 45°≤θ≤80°.

[0042] The second direction is actually also horizontal, specifically as follows: Figure 3As indicated by the arrow X. Regarding the tilt angle setting, if the angle is set too large, such as a maximum of 90°, while the support and stiffness will be stronger, the deformation capacity of the buffer column 21 will be weaker. If the angle is set too small, the buffer column 21 will have strong deformation capacity, but the support and stiffness will be insufficient. Through multiple demonstrations, combined with mechanical design principles and experiments, the applicant has concluded that the tilt angle setting range can be 45°≤θ≤80°, that is, the tilt angle can be 45 degrees, 55 degrees, 60 degrees, 70 degrees, or 80 degrees, or any value within the above range. Of course, the above-mentioned tilt angle θ range is only a specific embodiment and does not constitute a limitation on the tilt angle range.

[0043] Reference Figure 5 In some embodiments, the dimension of the buffer post 21 along the first direction is defined as the length of the buffer post 21, and the dimension of the buffer post 21 along the second direction is defined as the width of the buffer post 21. The aspect ratio A of the buffer post 21 is length / width, therefore: 1 ≤ A ≤ 3. (Refer to...) Figure 3 In this embodiment, the length of the buffer pillar 21 refers to its dimension along the first direction, denoted as L and the width as H, then A = L / H. If the aspect ratio is set large, meaning the ratio of length to width is very large, the buffer pillar 21 will have a slender structure. This type of buffer pillar 21 has low structural rigidity, is prone to collapse, and is more difficult to manufacture during etching. If the aspect ratio is small, deformation is less likely to occur because the aspect ratio can be limited to a reasonable range. In this embodiment, 1 ≤ A ≤ 3, meaning A can be one of 1, 1.5, 2, 2.5, or 3, or any value within the above range.

[0044] Reference Figure 4 and Figure 6 In some embodiments, the buffer layer 2 further includes a reinforcing member 23, which is disposed on the base layer 1 and extends toward the buffer pillar 21. Since multiple gaps 22 are formed on the original buffer plate to create the buffer layer 2, the strength of the buffer layer 2 is actually reduced, which affects its ability to withstand mechanical and thermal stresses. Therefore, a reinforcing member 23 can be disposed on the base layer 1, extending toward the buffer pillar 21. The reinforcing member 23 can abut against the buffer pillar 21 or be disposed at a small distance from it. Abutting against it reduces lateral bending of the buffer pillar 21, thus strengthening it. Distributing it at a small distance allows the buffer pillar 21 to deform to a certain extent before abutting against it, reducing the risk of further lateral bending or collapse. This absorbs stress and reduces the risk of collapse due to excessive deformation of the buffer pillar 21.

[0045] Reference Figure 4 and Figure 6In some embodiments, the reinforcing member 23 includes a bottom surface 231 and an abutment surface 232 connected to the bottom surface 231. The bottom surface 231 is disposed on the base layer 1, and the abutment surface 232 faces the inclined surface 213 of the buffer column 21. The included angle between the bottom surface 231 and the abutment surface 232 is defined as α, then (θ-α)∈[0°, 10°], that is, 0°≤θ-α≤10°. The inclined surface 213 of the buffer column 21 is actually the side surface along the second direction. The reinforcing member 23 can be an irregular shape or a regular shape. For example, the cross-section of a regular shape can be a triangle. The bottom surface 231 of the triangle is disposed on the base layer 1 and abuts against the base layer 1, or in other words, it is disposed on the base layer 1. One inclined surface of the triangle, namely the abutment surface 232, is disposed opposite to the inclined surface 213. The abutment surface 232 can abut against the inclined surface 213 to reduce the risk of further deformation of the buffer column 21. In some preferred embodiments, the contact surface 232 is fitted to the inclined surface 213 of the buffer column 21, and the angle α between the bottom surface 231 and the contact surface 232 is equal to the inclination angle θ. This reduces the lateral and vertical deformation of the buffer column 21 and improves the stability of the buffer structure. Of course, the angle between the bottom surface 231 and the contact surface 232 can also be less than θ. In this way, the buffer column 21 will only come into contact with the contact surface 232 after undergoing a certain deformation. Thus, while ensuring stress absorption capacity, the risk of collapse caused by excessive deformation of the buffer column 21 can be reduced.

[0046] In some embodiments, a plurality of buffer pillars 21 are arranged in an array on the substrate layer 1. The number of buffer pillars 21 is multiple, and depending on the etching method, the multiple buffer pillars 21 can be arranged in an array, or in a honeycomb or grid pattern. As for the shape of each buffer pillar 21, it can also be pyramidal or conical, such shapes have a large supporting area at the bottom 212, resulting in a more stable structure and lower etching difficulty. Of course, the shape of the buffer pillars 21 can also be cylindrical or prismatic, such as hexagonal prisms. A honeycomb or grid pattern arrangement of the buffer pillars 21 provides more uniform mechanical properties and better stress isolation.

[0047] It should be noted that the fabrication method of the MEMS chip in this application can employ a conventional approach, namely layer-by-layer deposition and etching, to deposit a layered buffer layer on the substrate layer 1, then obtain the buffer layer 2 through exposure, development, and etching, followed by the sequential deposition of the insulating layer 3, the fixed electrode layer 5, the isolation layer 4, and the movable electrode layer 6. However, the applicant has discovered that the conventional method generally does not include the buffer layer 2, thus eliminating the risk of deposits accumulating in the gaps 22 of the buffer layer 2 during subsequent deposition processes. If the gaps 22 are filled, the stress absorption capacity of the buffer layer 2 will be significantly reduced, which is detrimental to improving the detection accuracy and temperature stability of the MEMS chip 100 and the sensor 1000 it fabricates. Therefore, this application proposes a new method for fabricating a MEMS chip.

[0048] Reference Figure 7 , Figure 7 This is a schematic flowchart illustrating the method for fabricating a MEMS chip according to the first embodiment of this application. The method for fabricating a MEMS chip can be used in the fabrication of any of the aforementioned MEMS chip 100. The method for fabricating a MEMS chip includes the following steps: S100 provides a first substrate and a second substrate.

[0049] Both the first and second substrates can be silicon substrates. In related technologies, MEMS chips 100 are generally fabricated by setting up various layers on a single substrate, while this embodiment of the application uses two silicon substrates.

[0050] S200, an insulating layer 3, a fixed electrode layer 5, an isolation layer 4 and a movable electrode layer 6 are sequentially disposed on the first substrate.

[0051] The aforementioned layers can be configured using conventional methods, such as depositing an insulating layer 3 on a first substrate by deposition, etching grooves in the insulating layer 3, depositing a fixed electrode layer 5 within the grooves by deposition, or directly depositing the fixed electrode layer 5 on the insulating layer 3. A sacrificial layer is then deposited on the fixed electrode layer 5, and a movable electrode layer 6 is deposited on the sacrificial layer. A release hole is provided on the movable electrode layer 6, through which etching solution enters and etches the sacrificial layer. The etched portion of the sacrificial layer forms a through-hole, allowing the movable electrode layer 6 and the fixed electrode layer 5 to face each other and form two electrodes for the capacitor. A gap 7 is formed between the movable electrode layer 6 and the fixed electrode layer 5, and the remaining outer sacrificial layer serves as an isolation layer 4, providing insulation and isolation.

[0052] S300, a buffer layer 2 is provided on the second substrate, the buffer layer 2 including a plurality of buffer pillars 21 and a gap 22 provided between two adjacent buffer pillars 21.

[0053] Etching is performed on one side of the second substrate to form an etched hole, and the unetched part forms a buffer pillar 21. The etched hole is the gap 22 between adjacent buffer pillars 21. The buffer pillars 21 and the gap 22 form a buffer layer 2. A base layer 1 is formed on the other side of the second substrate.

[0054] Step S200 is the processing of the first substrate, and step S300 is the processing of the second substrate. Specifically, the buffer layer 2 can be provided on the second substrate in the following two ways.

[0055] The first method involves depositing a buffer material layer on a second substrate, etching multiple gaps 22 on the buffer material layer using photolithography, forming buffer pillars 21 in the unetched portions, and forming a buffer layer 2 with the buffer pillars 21 and the gaps 22, with the second substrate serving as the base layer 1.

[0056] The second method involves directly etching a buffer layer 2 onto the second substrate. Specifically, the second substrate includes one side and another side arranged along the thickness direction. An etching hole is formed on one side of the second substrate; this etching hole serves as a gap 22. The unetched portion forms a buffer pillar 21. Multiple buffer pillars 21 are spaced apart, and the etching hole serves as the gap 22 between adjacent buffer pillars 21. The buffer pillars 21 and the gaps 22 together form the buffer layer 2. For second substrates that are not completely etched, a portion that remains unetched along the thickness direction from the other side forms the substrate layer 1 of the MEMS chip 100.

[0057] S400, the buffer layer 2 is bonded to the side of the first substrate away from the insulating layer 3.

[0058] The connection method here can be bonding, specifically silicon bonding. The side of the buffer layer 2 facing away from the base layer 1 is bonded to the side of the first substrate facing away from the insulating layer 3. Finally, pads 8 and leads are added. There are at least two pads 8. One pad 8 is electrically connected to the fixed electrode layer 5 via a lead, and the other pad 8 is electrically connected to the movable electrode layer 6 via a lead. Of course, the first substrate and the second substrate can also be directly bonded, and the size of the buffer layer 2 between the first substrate and the second substrate is smaller than the size of the first substrate and the second substrate.

[0059] In the above embodiments of the present invention, an insulating layer 3, a fixed electrode layer 5, an isolation layer 4, and a movable electrode layer 6 are disposed on a first substrate, and a buffer layer 2 is disposed on a second substrate. Then, the MEMS chip 100 is fabricated by bonding the side of the buffer layer 2 away from the base layer 1 to the side of the first substrate away from the insulating layer 3. Compared to conventional fabrication methods, this application involves disposing the buffer layer 2 on the second substrate and then bonding it to the first substrate with the disposed insulating layer 3, fixed electrode layer 5, isolation layer 4, and movable electrode layer 6. Specifically, the side of the buffer layer 2 away from the base layer 1 is bonded to the side of the first substrate away from the insulating layer 3. This reduces the risk of etched material falling into the gap 22 of the buffer layer 2 during fabrication, thereby ensuring the buffer layer 2's ability to absorb stress deformation, which helps reduce the deformation of the MEMS chip 100 and improves the detection accuracy of the sensor 1000.

[0060] Reference Figure 8 , Figure 8 This is a schematic flowchart illustrating the method for fabricating a MEMS chip according to the second embodiment of this application. Following step S200, the method further includes the following step: S210, the first substrate is thinned from the side of the first substrate away from the insulating layer 3.

[0061] Compared to conventional fabrication methods, this embodiment adds a first substrate layer. However, the first substrate does not significantly affect the finished MEMS chip 100, as it can also serve as an insulating layer 3. To prevent the overall thickness of the MEMS chip 100 from exceeding preset requirements, and to ensure the buffer layer 2 can better fulfill its buffering function, the first substrate can be thinned. Specifically, this thinning can be achieved through mechanical grinding or etching.

[0062] Reference Figure 9 , Figure 9 This is a schematic flowchart illustrating a method for fabricating a MEMS chip according to a third embodiment of this application. Following step S400, the method further includes the following step: S500, the second substrate is thinned from the side of the second substrate away from the buffer layer 2.

[0063] Similar to the previous embodiment, since an additional first substrate is provided, the final thickness of the product may exceed the preset requirements. Therefore, the second substrate can be thinned. Specifically, the second substrate can be thinned from the side away from the buffer layer 2. The thinning method can also be mechanical grinding or etching.

[0064] For detailed steps on the fabrication of specific MEMS chips, please refer to [link / reference]. Figure 10 .

[0065] Reference Figure 11 , Figure 11 This is a schematic flowchart illustrating a method for fabricating a MEMS chip according to a fourth embodiment of this application. The method for fabricating a MEMS chip can be used in the fabrication of any of the aforementioned MEMS chip 100. The method for fabricating a MEMS chip includes the following steps: S1000 provides a first substrate and a second substrate; the first substrate includes a first side and a second side disposed opposite to each other.

[0066] Both the first and second substrates can be silicon substrates. In related technologies, MEMS chips 100 are typically fabricated by setting up various layers on a single substrate, while this embodiment uses two silicon substrates. The first and second sides of the first substrate are arranged opposite to each other, that is, on both sides along the thickness direction of the first substrate.

[0067] S2000, an insulating layer 3 is provided on the first side and a buffer layer 2 is provided on the second side. The buffer layer 2 includes a plurality of buffer pillars 21 and a gap 22 provided between two adjacent buffer pillars 21.

[0068] An insulating layer 3 is first provided on the first side to protect the first side of the first substrate, and then a buffer layer 2 is provided on the second side. The buffer layer 2 can be provided on the second side in the following two ways.

[0069] The first method involves depositing a buffer material layer on the second side and etching multiple gaps 22 on the buffer material layer using photolithography. The unetched portions form buffer pillars 21, and the buffer pillars 21 and gaps 22 form a buffer layer 2.

[0070] The second method is to directly etch a buffer layer 2 on the second side. Specifically, the second substrate includes one side and another side arranged along the thickness direction. An etching hole is formed on one side of the second substrate, and the unetched part forms a buffer pillar 21. There are multiple buffer pillars 21, which are spaced apart. The etching hole is the gap 22 between adjacent buffer pillars 21. The buffer pillars 21 and the gap 22 form the buffer layer 2.

[0071] S3000, connect the second substrate to the buffer layer 2.

[0072] The connection method here can be bonding, specifically silicon bonding. The second substrate serves as the substrate layer 1 of the MEMS chip 100.

[0073] S4000, a fixed electrode layer 5, an isolation layer 4, and a movable electrode layer 6 are sequentially arranged on the insulating layer 3.

[0074] The aforementioned layers can be configured using conventional methods, such as depositing an insulating layer 3 on a first substrate by deposition, etching grooves in the insulating layer 3, depositing a fixed electrode layer 5 within the grooves by deposition, or directly depositing the fixed electrode layer 5 on the insulating layer 3. A sacrificial layer is then placed on the fixed electrode layer 5, followed by a movable electrode layer 6. A release hole is provided on the movable electrode layer 6, through which etchant enters and etches the sacrificial layer. The etched portion of the sacrificial layer forms a through-hole, allowing the movable electrode layer 6 and the fixed electrode layer 5 to face each other, forming the two electrodes of the capacitor. The remaining outer portion of the sacrificial layer acts as an insulating and isolating layer 4. Finally, pads 8 and leads are added. There are at least two pads 8, one of which is electrically connected to the fixed electrode layer 5 via a lead, and the other is electrically connected to the movable electrode layer 6 via a lead.

[0075] In the above embodiments of the present invention, an insulating layer 3 is provided on a first side of a first substrate, a buffer layer is provided on a second side, and then the second substrate is connected to the buffer layer 2. A fixed electrode layer 5, an isolation layer 4, and a movable electrode layer 6 are then sequentially provided on the insulating layer 3. After the buffer layer 2 is bonded to the second substrate, the buffer layer 2 is sealed between the second substrate and the first side. This reduces the risk of etched material falling into the gap 22 of the buffer layer 2 during subsequent fabrication, thereby ensuring the buffer layer 2's ability to absorb stress deformation, which helps reduce the deformation of the MEMS chip 100 and improve the detection accuracy of the sensor 1000.

[0076] In some embodiments, after the step of providing the insulating layer 3 on the first side and before the step of providing the buffer layer 2 on the second side, the following step is further included: Thinning is performed on the second side of the first substrate. Compared to conventional fabrication methods, this embodiment involves an additional first substrate layer. However, the first substrate does not significantly impact the fabricated MEMS chip 100, as it can also serve as an insulating layer 3. Nevertheless, to prevent the overall thickness of the MEMS chip 100 from exceeding preset requirements, and to ensure the buffer layer 2 functions more effectively, the second side of the first substrate can be thinned. Specifically, this thinning can be achieved through mechanical grinding or etching.

[0077] Reference Figure 12 , Figure 12 This is a schematic flowchart of a method for fabricating a MEMS chip according to the fifth embodiment of this application. Following step S4000, the method further includes the following step: S5000, the second substrate is thinned from the side of the second substrate away from the buffer layer 2.

[0078] Similar to the previous embodiment, since an additional first substrate is provided, the final thickness of the product may exceed the preset requirements. Therefore, the second substrate can be thinned. Specifically, the second substrate can be thinned from the side away from the buffer layer 2. The thinning method can also be mechanical grinding or etching.

[0079] Reference Figure 13 According to some embodiments of this application, this application provides a sensor 1000. The sensor 1000 includes a base plate 300 and a housing 400 covering the base plate 300. The base plate 300 and the housing 400 form a receiving cavity. An ASIC chip 200 and a MEMS chip 100 signal-connected to the ASIC chip 200 are disposed within the receiving cavity. The MEMS chip 100 is the aforementioned MEMS chip 100, and / or the MEMS chip 100 is fabricated using the aforementioned MEMS chip fabrication method. The sensor 1000 can be a barometer or a microphone sensor 1000, belonging to the category of capacitive barometric pressure sensors 1000. Since the sensor 1000 includes all the technical solutions of all embodiments of the aforementioned MEMS chip 100, it possesses at least all the beneficial effects brought by all the aforementioned technical solutions.

[0080] According to some embodiments of this application, this application provides an electronic device that includes the sensor 1000 described above. Since the electronic device incorporates all the technical solutions of all embodiments of the sensor 1000 described above, it possesses at least all the beneficial effects brought about by all the aforementioned technical solutions.

[0081] The above description is merely an optional embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the content of the specification and drawings of this application under the concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A MEMS chip, characterized in that, The device comprises a base layer, a buffer layer, an insulating layer, an isolation layer, and a movable electrode layer stacked sequentially. The insulating layer has a receiving groove, and a fixed electrode layer is disposed within the receiving groove. The isolation layer has through holes corresponding to at least a portion of the fixed electrode layer, so that the fixed electrode layer and the movable electrode layer are arranged facing each other and separated by a gap. The buffer layer includes multiple buffer pillars arranged at intervals. Each buffer pillar includes a bottom and a top arranged opposite each other. The bottom abuts against the base layer, and the top abuts against the insulating layer. A gap is provided between any two adjacent buffer pillars.

2. The MEMS chip according to claim 1, characterized in that, The thickness direction of the base layer is defined as the first direction, and the buffer column is inclined relative to the first direction.

3. The MEMS chip according to claim 2, characterized in that, The direction perpendicular to the first direction and extending along the surface of the base layer is defined as the second direction, and the angle between the buffer column and the second direction is θ. Then, 45°≤θ≤80°.

4. The MEMS chip according to claim 3, characterized in that, The length of the buffer column along the first direction is defined as the length of the buffer column, and the width of the buffer column along the second direction is defined as the width of the buffer column. The length-to-width ratio A of the buffer column is length / width. Therefore, 1≤A≤3.

5. The MEMS chip according to claim 3, characterized in that, The buffer layer also includes a reinforcing member disposed on the base layer and extending toward the buffer post.

6. The MEMS chip according to claim 5, characterized in that, The reinforcing member includes a bottom surface and an abutting surface connected to the bottom surface. The bottom surface is disposed on the base layer, and the abutting surface is disposed facing the inclined surface of the buffer column. The included angle between the bottom surface and the abutting surface is defined as α, then (θ-α)∈[0°, 10°].

7. The MEMS chip according to claim 6, characterized in that, The contact surface is fitted to the inclined surface of the buffer post.

8. The MEMS chip according to any one of claims 1 to 7, characterized in that, The buffer pillars are arranged in an array on the base layer.

9. A method for fabricating a MEMS chip, characterized in that, Includes the following steps: Provide a first substrate and a second substrate; An insulating layer, a fixed electrode layer, an isolation layer, and a movable electrode layer are sequentially disposed on the first substrate. A buffer layer is provided on the second substrate, the buffer layer including a plurality of buffer pillars and a gap provided between two adjacent buffer pillars; The buffer layer is bonded to the side of the first substrate opposite to the insulating layer.

10. The method for fabricating a MEMS chip according to claim 9, characterized in that, After the step of sequentially setting an insulating layer, a fixed electrode layer, an isolation layer, and a movable electrode layer on the first substrate, the method further includes the following step: The first substrate is thinned from the side of the first substrate away from the insulating layer.

11. The method for fabricating a MEMS chip according to claim 9, characterized in that, After the step of bonding the buffer layer to the side of the first substrate away from the insulating layer, the method further includes the step of: The second substrate is thinned from the side of the second substrate away from the buffer layer.

12. A method for fabricating a MEMS chip, characterized in that, Includes the following steps: A first substrate and a second substrate are provided; the first substrate includes a first side and a second side disposed opposite to each other. An insulating layer is provided on the first side, and a buffer layer is provided on the second side. The buffer layer includes a plurality of buffer pillars and a gap between two adjacent buffer pillars. Connect the second substrate to the buffer layer; A fixed electrode layer, an isolation layer, and a movable electrode layer are sequentially disposed on the insulating layer.

13. The method for fabricating a MEMS chip according to claim 12, characterized in that, After the step of providing an insulating layer on the first side and before the step of providing a buffer layer on the second side, the method further includes the following step: The first substrate is thinned from the second side.

14. The method for fabricating a MEMS chip according to claim 12, characterized in that, After the step of sequentially setting the fixed electrode layer, the insulating layer, and the movable electrode layer on the insulating layer, the method further includes the following step: The second substrate is thinned from the side of the second substrate away from the buffer layer.

15. A sensor, characterized in that, The sensor includes a base plate and a housing covered by the base plate. The base plate and the housing form a receiving cavity. An ASIC chip and a MEMS chip signal-connected to the ASIC chip are disposed in the receiving cavity. The MEMS chip is the MEMS chip according to any one of claims 1 to 8; and / or, the MEMS chip is manufactured by the method of manufacturing the MEMS chip according to any one of claims 9 to 14.

16. An electronic device, characterized in that, The electronic device includes the sensor of claim 15.

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