WO2024041638A1 - 一种差分电容式mems压力传感器及其制造方法 - Google Patents

一种差分电容式mems压力传感器及其制造方法 Download PDF

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WO2024041638A1
WO2024041638A1 PCT/CN2023/114948 CN2023114948W WO2024041638A1 WO 2024041638 A1 WO2024041638 A1 WO 2024041638A1 CN 2023114948 W CN2023114948 W CN 2023114948W WO 2024041638 A1 WO2024041638 A1 WO 2024041638A1
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electrode
upper electrode
cavity
pressure sensor
gap
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PCT/CN2023/114948
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English (en)
French (fr)
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朱恩成
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青岛歌尔智能传感器有限公司
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Publication of WO2024041638A1 publication Critical patent/WO2024041638A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/14—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators
    • G01L1/142—Measuring force or stress, in general by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators using capacitors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/12—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in capacitance, i.e. electric circuits therefor

Definitions

  • the present application relates to the field of microelectronics technology, and more specifically, to a differential capacitive MEMS pressure sensor and a manufacturing method thereof.
  • MEMS pressure sensors can be divided into strain gauge, piezoresistive, piezoelectric, vibration frequency, capacitive pressure sensors, etc. based on their principles.
  • the pressure sensor can directly convert the measured pressure into various forms of electrical signals to facilitate the centralized detection and control requirements of the system. Therefore, it is widely used in consumer electronics, smart home, automotive electronics, industrial control and other fields.
  • the design of mainstream MEMS capacitive pressure sensors mostly adopts the flat capacitive method, which forms a sensitive capacitance through the upper and lower plates.
  • the test pressure acts on the surface of the plate, it causes the plate to deform. Due to the change in the distance between the upper and lower plates, the trigger capacitance changes linearly.
  • flat capacitive pressure sensors due to its own principle characteristics, flat capacitive pressure sensors have poor linearity and are easily damaged by overload.
  • One purpose of this application is to provide a new technology solution for a differential capacitive MEMS pressure sensor and its manufacturing method.
  • a differential capacitive MEMS pressure sensor includes:
  • a substrate, the interior of the substrate is provided with a first accommodation cavity with an open end;
  • a support body one end of the support body is connected to the bottom of the first accommodation cavity, and divides the first accommodation cavity into a second accommodation cavity and a third accommodation cavity;
  • the fixed electrode includes a first lower electrode and a second lower electrode, the first lower electrode is located at the bottom of the second accommodation cavity, and the second lower electrode is located at the bottom of the third accommodation cavity;
  • the movable electrode includes a first upper electrode and a second upper electrode.
  • the first upper electrode and the second upper electrode are an integrated structure.
  • the movable electrode is connected to the other end of the support body. connect so that
  • the first upper electrode is located above the first lower electrode and forms a first cavity. There is a gap between the first upper electrode and the substrate. The first upper electrode and the first The lower electrode forms the first capacitor;
  • the second upper electrode is located above the second lower electrode and forms a second cavity.
  • the second cavity is a sealed cavity.
  • the second upper electrode and the second lower electrode form a second cavity.
  • the second cavity is a vacuum cavity.
  • the second accommodation cavity and the third accommodation cavity have the same volume.
  • the support column and the movable electrode are integrally formed.
  • the substrate is made of at least one of sapphire, silicon carbide and single crystal silicon.
  • the material of the fixed electrode is polysilicon.
  • the gap includes a first gap and a second gap, the gap formed between the first upper electrode and the substrate along the length direction of the substrate is the first gap, and the first upper electrode A gap formed between the electrode and the substrate along the width direction of the substrate is a second gap, and the second gap is distributed on both sides of the first upper electrode.
  • the size of the first gap is 10 ⁇ m, and the size of the second gap is 3 ⁇ m.
  • it also includes a welding pad, the welding pad including a fixed electrode welding pad and a movable electrode welding pad;
  • a first metallized via hole is provided in the substrate, and a second metallized via hole is provided in the support pillar.
  • the fixed electrode communicates with the first circuit in the first metallized via hole. narrate solid
  • the fixed electrode pad is electrically connected, and the first upper electrode is electrically connected to the movable electrode pad through a second circuit in the first metallized via hole and a third circuit in the second metallized via hole.
  • a manufacturing method of a differential capacitive MEMS pressure sensor includes the following steps:
  • a substrate is provided, and a first accommodation cavity is formed by etching on the substrate;
  • a second oxide layer is deposited and etched between the first lower electrode and the second lower electrode to form a support body that separates the first accommodation cavity into a second accommodation cavity and a third accommodation cavity. cavity; cavity
  • the sacrificial layer is released so that the first upper electrode is located above the first lower electrode and a first cavity is formed, with a gap between the first upper electrode and the substrate, and the first upper electrode is The electrode and the first lower electrode form a first capacitor;
  • the second upper electrode is located above the second lower electrode and forms a second cavity.
  • the second cavity is a sealed cavity.
  • the second upper electrode and the second lower electrode form a second cavity. capacitor.
  • the movable electrode is supported above the fixed electrode through the support body to form the first capacitor and the second capacitor.
  • the movement directions of the first upper electrode and the second upper electrode in the movable electrode are opposite, so that the plate distance d1 between the first upper electrode and the first lower electrode is equal to that of the second upper electrode.
  • the plate distance d2 between the second lower electrode and the second lower electrode will produce an opposite change value.
  • the first capacitor and the second capacitor will output a differential capacitance signal, which greatly improves the linearity and sensitivity of the pressure sensor. Compared with the traditional The output signal of the single capacitive pressure sensor is effectively enhanced, which can effectively improve the test accuracy of the pressure sensor.
  • FIG. 1 is a first schematic diagram of a differential capacitive MEMS pressure sensor according to an embodiment of the present disclosure.
  • FIG. 2 is a second schematic diagram of a differential capacitive MEMS pressure sensor according to an embodiment of the present disclosure.
  • FIG 3 is a top view of a differential capacitive MEMS pressure sensor according to an embodiment of the present disclosure.
  • Substrate 1. Support body; 3. Fixed electrode; 31. First lower electrode; 32. Second lower electrode; 4. Movable electrode; 41. First upper electrode; 42. Second upper electrode; 5 , gap; 51, first gap; 52, second gap; 6, pad; 61, fixed electrode pad; 62, movable electrode pad.
  • any specific values are to be construed as illustrative only and not as limiting. Accordingly, other examples of the exemplary embodiments may have different values.
  • a differential capacitive MEMS pressure sensor is provided.
  • the pressure sensor includes a substrate 1, a support 2, a fixed electrode 3 and a movable electrode 4.
  • a first accommodation cavity with an open end is provided inside the substrate 1 .
  • One end of the support body 2 is connected to the bottom of the first accommodation cavity, and divides the first accommodation cavity into a third two accommodation chambers and a third accommodation chamber.
  • the fixed electrode 3 includes a first lower electrode 31 and a second lower electrode 32 .
  • the first lower electrode 31 is located at the bottom of the second accommodation cavity.
  • the second lower electrode 32 is located at the bottom of the third accommodation cavity.
  • the movable electrode 4 includes a first upper electrode 41 and a second upper electrode 42 .
  • the first upper electrode 41 and the second upper electrode 42 have an integrated structure.
  • the movable electrode 4 is connected to the other end of the support body 2 so that
  • the first upper electrode 41 is located above the first lower electrode 31 and forms a first cavity. There is a gap 5 between the first upper electrode 41 and the substrate 1 .
  • the first upper electrode 41 and the first lower electrode 31 constitute a first capacitor.
  • the second upper electrode 42 is located above the second lower electrode 32 and forms a second cavity.
  • the second cavity is a sealed cavity.
  • the second upper electrode 42 and the second lower electrode 32 constitute a second capacitor.
  • the first upper electrode 41 and the second upper electrode 42 move in opposite directions, that is, deformation occurs in opposite directions.
  • the plate distance d1 between the first upper electrode 41 and the first lower electrode 31 is different from the second upper electrode 41 .
  • the plate distance d2 between the electrode 42 and the second lower electrode 32 will produce an opposite change value, and the first capacitor and the second capacitor will output a differential capacitance signal.
  • ⁇ , ⁇ 0 and S are fixed values.
  • d1 and d2 increases and the other decreases.
  • the capacitance of the first capacitor The capacitance C1 and the second capacitor C2 then change in reverse directions to form a differential signal.
  • the substrate 1 may be a rectangular parallelepiped.
  • a first accommodation cavity with an open end is provided inside the substrate 1 .
  • the support body 2 may be a rectangular parallelepiped.
  • the size of the support body 2 is adapted to the first accommodation cavity. Under the condition that the support body 2 is located in the first accommodation cavity, one end of the support body 2 is connected to the bottom of the first accommodation cavity, and the first accommodation cavity is divided into a second accommodation cavity and a third accommodation cavity.
  • the shapes of the substrate 1 and the support body 2 can also be other suitable shapes such as circles, rhombuses, etc., which are not limited here, and those skilled in the art can make selections according to actual needs.
  • the fixed electrode 3 includes a first lower electrode 31 and a second lower electrode 32 .
  • the first lower electrode 31 is located at the bottom of the second accommodation cavity.
  • the second lower electrode 32 is located at the bottom of the third accommodation cavity.
  • the movable electrode 4 includes a first upper electrode 41 and a second upper electrode 42 .
  • the first upper electrode 41 and the second upper electrode 42 have an integrated structure.
  • the movable electrode 4 is connected to the other end of the support body 2 so that
  • the first upper electrode 41 is located above the first lower electrode 31 and forms a first cavity. There is a gap 5 between the first upper electrode 41 and the substrate 1 .
  • the first upper electrode 41 and the first lower electrode 31 constitute a first capacitor.
  • the second upper electrode 42 is located above the second lower electrode 32 and forms a second cavity.
  • the second cavity is a sealed cavity.
  • the second upper electrode 42 and the second lower electrode 32 constitute a second capacitor.
  • the first upper electrode 41 and the second upper electrode 42 have an integrated structure.
  • the first upper electrode 41 can move in the opposite direction to the second upper electrode 42 , thereby causing a gap between the first upper electrode 41 and the first lower electrode 31
  • the plate distance d1 and the plate distance d2 between the second upper electrode 42 and the second lower electrode 32 will produce opposite changing values, and the first capacitor and the second capacitor will output differential capacitance signals.
  • the first upper electrode 41 is located above the first lower electrode 31 and forms a first cavity. There is a gap 5 between the first upper electrode 41 and the substrate 1 .
  • the first upper electrode 41 and the first lower electrode 31 constitute a first capacitor.
  • the second upper electrode 42 is located above the second lower electrode 32 and forms a second cavity.
  • the second cavity is a sealed cavity.
  • the second upper electrode 42 and the second lower electrode 32 constitute a second capacitor.
  • the second cavity is a sealed cavity. This prevents the second cavity from being connected to the external environment.
  • the external air pressure can drive the second upper electrode 42 to move closer to the second lower electrode 32, thereby causing the first upper electrode to move closer to the second lower electrode 32. 41 produces a movement away from the first lower electrode 31, and finally the first capacitor and the second capacitor will output a differential capacitance signal.
  • the movable electrode 4 is supported above the fixed electrode 3 through the support body 2 to form a first capacitor and a second capacitor.
  • the movement directions of the first upper electrode 41 and the second upper electrode 42 in the movable electrode 4 are opposite, so that the plate distance d between the first upper electrode 41 and the first lower electrode 31 is with the second upper electrode 42
  • the plate distance d between the second lower electrode 32 and the second lower electrode 32 will produce an opposite change value.
  • the first capacitor and the second capacitor will output a differential capacitance signal, which greatly improves the linearity and sensitivity of the pressure sensor. Compared with the traditional With the single capacitive pressure sensor, the output signal is effectively enhanced, which can effectively improve the test accuracy of the pressure sensor.
  • the second cavity is a vacuum cavity.
  • setting the second cavity as a vacuum cavity can facilitate the acquisition of absolute air pressure, eliminate the influence of temperature changes in the sealed cavity on the detection accuracy of the second capacitor, and further improve the detection accuracy of the pressure sensor.
  • the second accommodation cavity and the third accommodation cavity have the same volume.
  • the second accommodation cavity and the third accommodation cavity have the same volume.
  • the first capacitor and the second capacitor can have substantially the same initial capacitance, avoiding the difference in the initial capacitance of the first capacitor and the second capacitor under the condition of no pressure load, further improving the detection of the pressure sensor. Accuracy.
  • the volumes of the second accommodating cavity and the third accommodating cavity may also be different, and there is no limitation here. Those skilled in the art can make a selection according to actual needs.
  • the support column and the movable electrode 4 are integrally formed.
  • the support column and the movable electrode 4 are integrally formed. This can make the manufacturing process of the support column and the movable electrode 4 relatively simple, and can avoid the problem of unstable connection between the support column and the movable electrode 4 .
  • the material of the substrate 1 is at least one of silicon dioxide, silicon carbide and silicon nitride.
  • the material of the substrate 1 is selected to be at least one of silicon dioxide, silicon carbide and silicon nitride.
  • the above-mentioned materials are all non-conductive materials, and the hardness of the above-mentioned materials is relatively high, which is conducive to improving the structural strength of the pressure sensor, thereby enabling the substrate 1 to provide good and effective support for the fixed electrode 3, the support 2, and the movable electrode 4. of support.
  • the material of the fixed electrode 3 is polysilicon.
  • the material of the fixed electrode 3 is selected as polysilicon.
  • Polysilicon is a conductive material and has high hardness, so that the fixed electrode 3 can be stably fixed in the first accommodation cavity and is not prone to deformation.
  • the fixed electrode 3 can cooperate with the movable electrode 4 to form a capacitor. to output the capacitive signal.
  • the gap 5 includes a first gap 51 and a second gap 52 .
  • the gap 5 formed between the first upper electrode 41 and the substrate 1 along the length direction of the substrate 1 is the first gap 51 .
  • the gap 5 formed between the first upper electrode 41 and the substrate 1 along the width direction of the substrate 1 is a second gap 52 .
  • the second gaps 52 are distributed on both sides of the first upper electrode 41 .
  • the substrate 1 may be a rectangular parallelepiped.
  • a first accommodation cavity with an open end is provided inside the substrate 1 .
  • the receiving cavity is rectangular.
  • the gap 5 formed between the first upper electrode 41 and the substrate 1 along the length direction of the substrate 1 is the first gap 51 .
  • the gap 5 formed between the first upper electrode 41 and the substrate 1 along the width direction of the substrate 1 is a second gap 52 .
  • the second gaps 52 are distributed on both sides of the first upper electrode 41 .
  • the gap 5 can connect the first cavity to the external environment, thereby making the air pressure in the first cavity equal to the external air pressure.
  • the setting of the first gap 51 and the second gap 52 can ensure that under the condition that the second upper electrode 42 moves, the first upper electrode 41 can move in the opposite direction to the movement direction of the second upper electrode 42, thereby making the first upper electrode 42 move in the opposite direction.
  • the capacitor and the second capacitor can output differential signals.
  • the size of the first gap 51 is 10 ⁇ m, and the size of the second gap 52 is 3 ⁇ m.
  • the size of the first gap 51 is 10 ⁇ m.
  • the size of the second gap 52 is 3 ⁇ m.
  • the pressure sensor also includes pad 6 .
  • the pad 6 includes a fixed electrode pad 61 and a movable electrode pad 62 .
  • a first metallized via hole is provided in the substrate 1 .
  • a second metallized via hole is provided in the support pillar.
  • the fixed electrode 3 is electrically connected to the fixed electrode pad 61 through the first circuit in the first metalized via hole.
  • the first upper electrode 41 is electrically connected to the movable electrode pad 62 through a second circuit in the first metallized via hole and a third circuit in the second metallized via hole.
  • a first circuit and a second circuit are disposed in the first metallized via hole.
  • a third circuit is disposed in the second metallization via.
  • the fixed electrode 3 is electrically connected to the fixed electrode pad 61 through the first circuit in the first metallized via hole.
  • the first upper electrode 41 is electrically connected to the movable electrode pad 62 through a second circuit in the first metallized via hole and a third circuit in the second metallized via hole.
  • a fourth circuit is also provided in the first metallized via hole, and the second upper electrode 42 is electrically connected to the movable electrode pad 62 through the fourth circuit in the first metallized via hole.
  • the movable electrode 4 is supported above the fixed electrode 3 through the support body 2 and is electrically connected to the fixed electrode pad 61 and the movable electrode pad 62 through different circuits to form a first capacitor and a second capacitor.
  • the movement directions of the first upper electrode 41 and the second upper electrode 42 in the movable electrode 4 are opposite, so that the plate distance d1 between the first upper electrode 41 and the first lower electrode 31
  • the plate distance d2 between the second upper electrode 42 and the second lower electrode 32 will produce an opposite change value, and the first capacitor and the second capacitor will output a differential capacitance signal, which greatly improves the linearity of the pressure sensor. and sensitivity.
  • the output signal is effectively enhanced, which can effectively improve the test accuracy of the pressure sensor.
  • a manufacturing method of a differential capacitive MEMS pressure sensor includes the following steps:
  • Substrate 1 is provided.
  • a first accommodation cavity is formed on the substrate 1 by etching.
  • a first metal layer is deposited and etched at the bottom of the first accommodation cavity to form a first lower electrode 31 and a second lower electrode 32 that are independent of each other.
  • a second oxide layer is deposited and etched between the first lower electrode 31 and the second lower electrode 32 to form the support body 2 .
  • the support body 2 divides the first accommodation cavity into a second accommodation cavity and a third accommodation cavity.
  • a sacrificial layer is deposited in the second accommodation cavity and the third accommodation cavity.
  • a third oxide layer is deposited and etched on the sacrificial layer to form a first upper electrode 41 and a second upper electrode 42.
  • the sacrificial layer is released so that the first upper electrode 41 is located above the first lower electrode 31 and a first cavity is formed. There is a gap 5 between the first upper electrode 41 and the substrate 1 .
  • the first upper electrode 41 and the first lower electrode 31 constitute a first capacitor;
  • the second upper electrode 42 is located above the second lower electrode 32 and forms a second cavity.
  • the second cavity is a sealed cavity.
  • the second upper electrode 42 and the second lower electrode 32 constitute a second capacitor.
  • the movable electrode 4 is supported above the fixed electrode 3 through the support body 2 to form a first capacitor and a second capacitor.
  • the movement directions of the first upper electrode 41 and the second upper electrode 42 in the movable electrode 4 are opposite, so that the plate distance d1 between the first upper electrode 41 and the first lower electrode 31
  • the plate distance d2 between the second upper electrode 42 and the second lower electrode 32 will produce an opposite change value, and the first capacitor and the second capacitor will output a differential capacitance signal, which greatly improves the linearity of the pressure sensor. and sensitivity.
  • the output signal is effectively enhanced, which can effectively improve the test accuracy of the pressure sensor.

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

本申请公开了一种差分电容式MEMS压力传感器及其制造方法。该压力传感器包括:可动电极，所述可动电极包括第一上电极和第二上电极，所述第一上电极和所述第二上电极为一体结构，所述可动电极与所述支撑体的另一端连接，以使所述第一上电极位于所述第一下电极的上方，并形成第一腔体，所述第一上电极与所述衬底之间具有间隙，所述第一上电极和所述第一下电极构成第一电容器；所述第二上电极位于所述第二下电极的上方，并形成第二腔体，所述第二腔体为密闭腔体，所述第二上电极和所述第二下电极构成第二电容器；在施加压力载荷的条件下，所述第一上电极和所述第二上电极的运动方向相反。

Description

一种差分电容式MEMS压力传感器及其制造方法
本申请要求于2022年08月26日提交中国专利局，申请号为202211035642.6，申请名称为“一种差分电容式MEMS压力传感器及其制造方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及微电子技术领域，更具体地，涉及一种差分电容式MEMS压力传感器及其制造方法。
背景技术
MEMS压力传感器根据原理可分为应变式、压阻式、压电式、振频式、电容式压力传感器等。此外还有光电式、超声式、光纤式压力传感器等。采用压力传感器可以直接将被测压力变换成各种形式的电信号，便于满足系统集中检测与控制的要求，因而在消费类电子、智能家居、汽车电子、工业控制等领域有着广泛的应用。
目前主流MEMS电容式压力传感器的设计多采用平板电容方式，通过上下极板形成敏感电容，当测试压力作用于极板表面，导致极板形变，由于上下极板的距离改变，触发电容线性变化。但平板电容压力传感器由于本身原理特性，存在线性度较差，易过载破损等情况。
因此，亟需提出一种新的技术方案，以解决上述技术问题。
发明内容
本申请的一个目的是提供一种差分电容式MEMS压力传感器及其制造方法的新技术方案。
根据本申请的第一方面，提供了一种差分电容式MEMS压力传感器。该压力传感器包括：
衬底，所述衬底的内部设置有一端敞口的第一容纳腔；
支撑体，所述支撑体的一端与所述第一容纳腔的底部连接，并将所述第一容纳腔分隔为第二容纳腔和第三容纳腔；
固定电极，所述固定电极包括第一下电极和第二下电极，所述第一下电极位于所述第二容纳腔的底部，所述第二下电极位于所述第三容纳腔的底部；
可动电极，所述可动电极包括第一上电极和第二上电极，所述第一上电极和所述第二上电极为一体结构，所述可动电极与所述支撑体的另一端连接，以使
所述第一上电极位于所述第一下电极的上方，并形成第一腔体，所述第一上电极与所述衬底之间具有间隙，所述第一上电极和所述第一下电极构成第一电容器；
所述第二上电极位于所述第二下电极的上方，并形成第二腔体，所述第二腔体为密闭腔体，所述第二上电极和所述第二下电极构成第二电容器；
在施加压力载荷的条件下，所述第一上电极和所述第二上电极的运动方向相反。
可选地，所述第二腔体为真空腔体。
可选地，所述第二容纳腔和所述第三容纳腔的体积相同。
可选地，所述支撑柱和所述可动电极一体成型。
可选地，所述衬底的材料为蓝宝石、碳化硅和单晶硅中的至少一种。
可选地，所述固定电极的材料为多晶硅。
可选地，所述间隙包括第一间隙和第二间隙，所述第一上电极沿所述衬底的长度方向与所述衬底之间形成的间隙为第一间隙，所述第一上电极沿所述衬底的宽度方向与所述衬底之间形成的间隙为第二间隙，所述第二间隙分布于所述第一上电极的两侧。
可选地，所述第一间隙的尺寸为10μm，所述第二间隙的尺寸为3μm。
可选地，还包括焊盘，所述焊盘包括固定电极焊盘和可动电极焊盘；
在所述衬底内设置有第一金属化过孔，在所述支撑柱内设置有第二金属化过孔，所述固定电极通过所述第一金属化过孔中的第一电路与所述固 定电极焊盘电连接，所述第一上电极通过所述第一金属化过孔中的第二电路和第二金属化过孔中的第三电路与所述可动电极焊盘电连接。
根据本申请的第二方面，提供了一种差分电容式MEMS压力传感器的制造方法。该方法包括如下步骤：
提供衬底，在所述衬底上刻蚀形成第一容纳腔；
在所述第一容纳腔的底部沉积并刻蚀第一金属层,形成相互独立的第一下电极和第二下电极；
在所述第一下电极和所述第二下电极之间沉积并刻蚀第二氧化层，形成支撑体，所述支撑体将所述第一容纳腔分隔为第二容纳腔和第三容纳腔；
在所述第二容纳腔和所述第三容纳腔内沉积牺牲层；
在所述牺牲层上沉积并刻蚀第三氧化层,形成第一上电极和第二上电极；
释放牺牲层，以使所述第一上电极位于所述第一下电极的上方，并形成第一腔体，所述第一上电极与所述衬底之间具有间隙，所述第一上电极和所述第一下电极构成第一电容器；以及
所述第二上电极位于所述第二下电极的上方，并形成第二腔体，所述第二腔体为密闭腔体，所述第二上电极和所述第二下电极构成第二电容器。
在本公开实施例中，可动电极通过支撑体支撑在固定电极的上方，以形成第一电容器和第二电容器。在施加压力载荷的条件下，可动电极中的第一上电极和第二上电极的运动方向相反，以使得第一上电极和第一下电极之间的极板距离d1与第二上电极和第二下电极之间的极板距离d2会产生相反的改变数值，第一电容器和第二电容器会输出差分电容信号，极大的提高了该压力传感器的线性度及灵敏度，相比较传统的单电容式压力传感器，输出信号得到有效增强，能够有效提高压力传感器的测试精度。
通过以下参照附图对本申请的示例性实施例的详细描述，本申请的其它特征及其优点将会变得清楚。
附图说明
被结合在说明书中并构成说明书的一部分的附图示出了本申请的实 施例，并且连同其说明一起用于解释本申请的原理。
图1是根据本公开实施例差分电容式MEMS压力传感器的第一示意图。
图2是根据本公开实施例差分电容式MEMS压力传感器的第二示意图。
图3是根据本公开实施例差分电容式MEMS压力传感器的俯视图。
附图标记说明：
1、衬底；2、支撑体；3、固定电极；31、第一下电极；32、第二下电极；4、可动电极；41、第一上电极；42、第二上电极；5、间隙；51、第一间隙；52、第二间隙；6、焊盘；61、固定电极焊盘；62、可动电极焊盘。
具体实施方式
现在将参照附图来详细描述本申请的各种示例性实施例。应注意到：除非另外具体说明，否则在这些实施例中阐述的部件和步骤的相对布置、数字表达式和数值不限制本申请的范围。
以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用或使用的任何限制。
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为说明书的一部分。
在这里示出和讨论的所有例子中，任何具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它例子可以具有不同的值。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步讨论。
根据本公开的第一个实施例，如图1所示，提供了一种差分电容式MEMS压力传感器。该压力传感器包括衬底1、支撑体2、固定电极3和可动电极4。
衬底1的内部设置有一端敞口的第一容纳腔。
支撑体2的一端与第一容纳腔的底部连接，并将第一容纳腔分隔为第 二容纳腔和第三容纳腔。
固定电极3包括第一下电极31和第二下电极32。第一下电极31位于第二容纳腔的底部。第二下电极32位于第三容纳腔的底部。
可动电极4包括第一上电极41和第二上电极42。第一上电极41和第二上电极42为一体结构。可动电极4与支撑体2的另一端连接，以使
第一上电极41位于第一下电极31的上方，并形成第一腔体。第一上电极41与衬底1之间具有间隙5。第一上电极41和第一下电极31构成第一电容器。
第二上电极42位于第二下电极32的上方，并形成第二腔体。第二腔体为密闭腔体。第二上电极42和第二下电极32构成第二电容器。
在施加压力载荷的条件下，第一上电极41和第二上电极42的运动方向相反。
需要说明的是，差分电容式MEMS压力传感器的工作原理为：
当施加压力载荷时，第一上电极41和第二上电极42运动方向相反，即产生相反方向的形变，第一上电极41和第一下电极31之间的极板距离d1与第二上电极42和第二下电极32之间的极板距离d2会产生相反的改变数值，第一电容器和第二电容器会输出差分电容信号。
电容计算方法为C＝ε*ε0*S/d，该设计中ε、ε0、S为固定值，当施加压力载荷时，d1与d2一个增大，一个减小，第一电容器的电容C1和第二电容器的电容C2随之反向变化形成差分信号。
例如，该衬底1可以为长方体。在衬底1的内部设置有一端敞口的第一容纳腔。
该支撑体2可以为长方体。支撑体2的尺寸与第一容纳腔适配。在支撑体2位于第一容纳腔的条件下，支撑体2的一端与第一容纳腔的底部连接，并将第一容纳腔分隔为第二容纳腔和第三容纳腔。
当然，衬底1和支撑体2的形状也可以是其他圆形、菱形等其他合适的形状，在此不做限制，本领域技术人员可以根据实际需要进行选择。
固定电极3包括第一下电极31和第二下电极32。第一下电极31位于第二容纳腔的底部。第二下电极32位于第三容纳腔的底部。
可动电极4包括第一上电极41和第二上电极42。第一上电极41和第二上电极42为一体结构。可动电极4与支撑体2的另一端连接，以使
第一上电极41位于第一下电极31的上方，并形成第一腔体。第一上电极41与衬底1之间具有间隙5。第一上电极41和第一下电极31构成第一电容器。
第二上电极42位于第二下电极32的上方，并形成第二腔体。第二腔体为密闭腔体。第二上电极42和第二下电极32构成第二电容器。
在施加压力载荷的条件下，第一上电极41和第二上电极42的运动方向相反。
例如，第一上电极41和第二上电极42为一体结构。这样使得，在第二上电极42上施加压力载荷的条件下，第一上电极41能够产生与第二上电极42相反方向的运动，进而使得第一上电极41和第一下电极31之间的极板距离d1与第二上电极42和第二下电极32之间的极板距离d2会产生相反的改变数值，第一电容器和第二电容器会输出差分电容信号。
例如，第一上电极41位于第一下电极31的上方，并形成第一腔体。第一上电极41与衬底1之间具有间隙5。第一上电极41和第一下电极31构成第一电容器。第一上电极41与衬底1之间具有间隙5，这样使得第一腔体与外界环境连通，进而使得第一腔体内的气压与外界气压相等，在第二上电极42未受到压力载荷的条件下，第一上电极41不发生形变。
例如，第二上电极42位于第二下电极32的上方，并形成第二腔体。第二腔体为密闭腔体。第二上电极42和第二下电极32构成第二电容器。第二腔体为密闭腔体。这样使得第二腔体与外界环境无法连通，在第二上电极42受到压力载荷的条件下，外界气压能够驱动第二上电极42产生靠近第二下电极32的运动，进而使得第一上电极41产生远离第一下电极31的运动，最终使得第一电容器和第二电容器会输出差分电容信号。
在本公开实施例中，如图2所示，可动电极4通过支撑体2支撑在固定电极3的上方，以形成第一电容器和第二电容器。在施加压力载荷的条件下，可动电极4中的第一上电极41和第二上电极42的运动方向相反，以使得第一上电极41和第一下电极31之间的极板距离d与第二上电极42 和第二下电极32之间的极板距离d会产生相反的改变数值，第一电容器和第二电容器会输出差分电容信号，极大的提高了该压力传感器的线性度及灵敏度，相比较传统的单电容式压力传感器，输出信号得到有效增强，能够有效提高压力传感器的测试精度。
在一个例子中，第二腔体为真空腔体。
例如，将第二腔体设置为真空腔体，能够便于获得绝对气压，消除密闭腔体的温度变化等对第二电容器的检测精度的影响，进一步提高了该压力传感器的检测精度。
在一个例子中，第二容纳腔和第三容纳腔的体积相同。
例如，第二容纳腔和第三容纳腔的体积相同。这样能够使得第一电容器和第二电容器具有基本相同的初始电容量，避免了在没有压力载荷的条件下，第一电容器和第二电容器的初始电容量具有差异，进一步提高了该压力传感器的检测精度。
当然，第二容纳腔和第三容纳腔的体积也可以不相同，在此不做限制，本领域技术人员可以根据实际需要进行选择。
在一个例子中，支撑柱和可动电极4一体成型。
例如，支撑柱和可动电极4一体成型。这样能够使得支撑柱和可动电极4的制造工艺比较简单，而且能够避免支撑柱和可动电极4连接不稳定的问题。
在一个例子中，衬底1的材料为二氧化硅、碳化硅和氮化硅中的至少一种。
例如，将衬底1的材料选择为二氧化硅、碳化硅和氮化硅中的至少一种。上述材料均为不导电的材料，而且上述材料的硬度较高，有利于提高该压力传感器的结构强度，进而使得该衬底1能够为固定电极3、支撑体2、可动电极4提供良好有效的支撑。
在一个例子中，固定电极3的材料为多晶硅。
例如，将固定电极3的材料选择为多晶硅。多晶硅为导电材料，而且硬度高，这样能够使得该固定电极3能够被稳定固定于第一容纳腔内，并且不易发生形变，同时，该固定电极3能够与可动电极4配合形成电容器， 以输出电容信号。
在一个例子中，间隙5包括第一间隙51和第二间隙52。第一上电极41沿衬底1的长度方向与衬底1之间形成的间隙5为第一间隙51。第一上电极41沿衬底1的宽度方向与衬底1之间形成的间隙5为第二间隙52。第二间隙52分布于第一上电极41的两侧。
例如，如图3所示，该衬底1可以为长方体。在衬底1的内部设置有一端敞口的第一容纳腔。该容纳腔为长方形。
可动电极4通过该支撑体2设置于固定电极3的上方时，第一上电极41沿衬底1的长度方向与衬底1之间形成的间隙5为第一间隙51。第一上电极41沿衬底1的宽度方向与衬底1之间形成的间隙5为第二间隙52。第二间隙52分布于第一上电极41的两侧。该间隙5能够使得第一腔体与外界环境连通，进而使得第一腔体内的气压与外界气压相等，在第二上电极42未受到压力载荷的条件下，第一上电极41不发生形变。同时，第一间隙51和第二间隙52的设置能够保证在第二上电极42运动的条件下，第一上电极41能够朝向与第二上电极42运动方向相反的方向运动，进而使得第一电容器和第二电容器能够输出差分信号。
在一个例子中，第一间隙51的尺寸为10μm，第二间隙52的尺寸为3μm。
例如，第一间隙51的尺寸为10μm。第二间隙52的尺寸为3μm。将第一间隙51和第二间隙52的尺寸控制在该范围内，在保证第一腔体与外界环境连通的条件下，不会使得第一上电极41与第二上电极42之间面积之差过大，避免了第一上电极41和第二上电极42由于电极面积相差带来的初始电容量相差过大的问题，进而也提高了该压力传感器的测量精度。
在一个例子中，该压力传感器还包括焊盘6。焊盘6包括固定电极焊盘61和可动电极焊盘62。
在衬底1内设置有第一金属化过孔。在支撑柱内设置有第二金属化过孔。固定电极3通过第一金属化过孔中的第一电路与固定电极焊盘61电连接。第一上电极41通过第一金属化过孔中的第二电路和第二金属化过孔中的第三电路与可动电极焊盘62电连接。
例如，在第一金属化过孔中设置有第一电路和第二电路。在第二金属化过孔中设置有第三电路。该固定电极3通过第一金属化过孔中的第一电路与固定电极焊盘61电连接。第一上电极41通过第一金属化过孔中的第二电路和第二金属化过孔中的第三电路与可动电极焊盘62电连接。
例如，在第一金属化过孔中还设置有第四电路，第二上电极42通过第一金属化通孔中的第四电路与可动电极焊盘62电连接。
可动电极4通过支撑体2支撑在固定电极3的上方，分别通过不同的电路与固定电极焊盘61和可动电极焊盘62实现电连接，以形成第一电容器和第二电容器。在施加压力载荷的条件下，可动电极4中的第一上电极41和第二上电极42的运动方向相反，以使得第一上电极41和第一下电极31之间的极板距离d1与第二上电极42和第二下电极32之间的极板距离d2会产生相反的改变数值，第一电容器和第二电容器会输出差分电容信号，极大的提高了该压力传感器的线性度及灵敏度，相比较传统的单电容式压力传感器，输出信号得到有效增强，能够有效提高压力传感器的测试精度。
根据本公开的第二个实施例，提供了一种差分电容式MEMS压力传感器的制造方法。该方法包括如下步骤：
提供衬底1。在衬底1上刻蚀形成第一容纳腔。
在第一容纳腔的底部沉积并刻蚀第一金属层,形成相互独立的第一下电极31和第二下电极32。
在第一下电极31和第二下电极32之间沉积并刻蚀第二氧化层，形成支撑体2。支撑体2将第一容纳腔分隔为第二容纳腔和第三容纳腔。
在第二容纳腔和第三容纳腔内沉积牺牲层。
在牺牲层上沉积并刻蚀第三氧化层,形成第一上电极41和第二上电极42。
释放牺牲层，以使第一上电极41位于第一下电极31的上方，并形成第一腔体。第一上电极41与衬底1之间具有间隙5。第一上电极41和第一下电极31构成第一电容器；以及
第二上电极42位于第二下电极32的上方，并形成第二腔体。第二腔体为密闭腔体。第二上电极42和第二下电极32构成第二电容器。
在本公开实施例中，可动电极4通过支撑体2支撑在固定电极3的上方，以形成第一电容器和第二电容器。在施加压力载荷的条件下，可动电极4中的第一上电极41和第二上电极42的运动方向相反，以使得第一上电极41和第一下电极31之间的极板距离d1与第二上电极42和第二下电极32之间的极板距离d2会产生相反的改变数值，第一电容器和第二电容器会输出差分电容信号，极大的提高了该压力传感器的线性度及灵敏度，相比较传统的单电容式压力传感器，输出信号得到有效增强，能够有效提高压力传感器的测试精度。
上文实施例中重点描述的是各个实施例之间的不同，各个实施例之间不同的优化特征只要不矛盾，均可以组合形成更优的实施例，考虑到行文简洁，在此则不再赘述。
虽然已经通过例子对本申请的一些特定实施例进行了详细说明，但是本领域的技术人员应该理解，以上例子仅是为了进行说明，而不是为了限制本申请的范围。本领域的技术人员应该理解，可在不脱离本申请的范围和精神的情况下，对以上实施例进行修改。本申请的范围由所附权利要求来限定。

Claims (10)

  1. 一种差分电容式MEMS压力传感器，其特征在于，包括:
    衬底，所述衬底的内部设置有一端敞口的第一容纳腔；
    支撑体，所述支撑体的一端与所述第一容纳腔的底部连接，并将所述第一容纳腔分隔为第二容纳腔和第三容纳腔；
    固定电极，所述固定电极包括第一下电极和第二下电极，所述第一下电极位于所述第二容纳腔的底部，所述第二下电极位于所述第三容纳腔的底部；
    可动电极，所述可动电极包括第一上电极和第二上电极，所述第一上电极和所述第二上电极为一体结构，所述可动电极与所述支撑体的另一端连接，以使
    所述第一上电极位于所述第一下电极的上方，并形成第一腔体，所述第一上电极与所述衬底之间具有间隙，所述第一上电极和所述第一下电极构成第一电容器；
    所述第二上电极位于所述第二下电极的上方，并形成第二腔体，所述第二腔体为密闭腔体，所述第二上电极和所述第二下电极构成第二电容器；
    在施加压力载荷的条件下，所述第一上电极和所述第二上电极的运动方向相反。
  2. 根据权利要求1所述的差分电容式MEMS压力传感器，其特征在于，所述第二腔体为真空腔体。
  3. 根据权利要求1或2所述的差分电容式MEMS压力传感器，其特征在于，所述第二容纳腔和所述第三容纳腔的体积相同。
  4. 根据权利要求1-3中任一项所述的差分电容式MEMS压力传感器，其特征在于，所述支撑柱和所述可动电极一体成型。
  5. 根据权利要求1-4中任一项所述的差分电容式MEMS压力传感器，其特征在于，所述衬底的材料为蓝宝石、碳化硅和单晶硅中的至少一种。
  6. 根据权利要求1-5中任一项所述的差分电容式MEMS压力传感器，其特征在于，所述固定电极的材料为多晶硅。
  7. 根据权利要求1-6中任一项所述的差分电容式MEMS压力传感器，其特征在于，所述间隙包括第一间隙和第二间隙，所述第一上电极沿所述衬底的长度方向与所述衬底之间形成的间隙为第一间隙，所述第一上电极沿所述衬底的宽度方向与所述衬底之间形成的间隙为第二间隙，所述第二间隙分布于所述第一上电极的两侧。
  8. 根据权利要求7所述的差分电容式MEMS压力传感器，其特征在于，所述第一间隙的尺寸为10μm，所述第二间隙的尺寸为3μm。
  9. 根据权利要求1-7中任一项所述的差分电容式MEMS压力传感器，其特征在于，还包括焊盘，所述焊盘包括固定电极焊盘和可动电极焊盘；
    在所述衬底内设置有第一金属化过孔，在所述支撑柱内设置有第二金属化过孔，所述固定电极通过所述第一金属化过孔中的第一电路与所述固定电极焊盘电连接，所述第一上电极通过所述第一金属化过孔中的第二电路和第二金属化过孔中的第三电路与所述可动电极焊盘电连接。
  10. 一种差分电容式MEMS压力传感器的制造方法，其特征在于，所述差分电容式MEMS压力传感器为权利要求1-9中任一项所述的差分电容式MEMS压力传感器；
    所述差分电容式MEMS压力传感器的制造方法包括如下步骤：
    提供衬底，在所述衬底上刻蚀形成第一容纳腔；
    在所述第一容纳腔的底部沉积并刻蚀第一金属层,形成相互独立的第一下电极和第二下电极；
    在所述第一下电极和所述第二下电极之间沉积并刻蚀第二氧化层，形成支撑体，所述支撑体将所述第一容纳腔分隔为第二容纳腔和第三容纳腔；
    在所述第二容纳腔和所述第三容纳腔内沉积牺牲层；
    在所述牺牲层上沉积并刻蚀第三氧化层,形成第一上电极和第二上电极；
    释放牺牲层，以使所述第一上电极位于所述第一下电极的上方，并形成第一腔体，所述第一上电极与所述衬底之间具有间隙，所述第一上电极和所述第一下电极构成第一电容器；以及
    所述第二上电极位于所述第二下电极的上方，并形成第二腔体，所述第二腔体为密闭腔体，所述第二上电极和所述第二下电极构成第二电容器。
PCT/CN2023/114948 2022-08-26 2023-08-25 一种差分电容式mems压力传感器及其制造方法 WO2024041638A1 (zh)

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CN115452207A (zh) * 2022-08-26 2022-12-09 青岛歌尔智能传感器有限公司 一种差分电容式mems压力传感器及其制造方法

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