Capacitive pressure sensitive chip

Abstract

The application relates to a capacitive pressure-sensitive chip, in particular to a capacitive pressure-sensitive chip. The capacitive pressure-sensitive chip has excellent performance. The capacitive pressure-sensitive chip comprises a substrate, wherein a pressure-sensing lower plate is arranged on the substrate, a pressure-sensing upper plate is arranged above the lower plate, and a cavity is arranged between the upper plate and the lower plate.

Description

Technical Field

[0001] This invention belongs to the field of microelectromechanical systems (MEMS) technology, and particularly relates to a capacitive pressure-sensitive chip. Background Technology

[0002] With the development of MEMS technology, pressure sensors have become indispensable key components in various industries, and have been widely used in automotive electronics, petrochemicals, biomedicine, and national defense. Compared with piezoresistive pressure sensors, capacitive pressure sensors have advantages such as high sensitivity, low power consumption, and good temperature characteristics, making them more suitable for developing high-precision pressure sensors. Especially against the backdrop of increasingly stringent requirements for pressure measurement accuracy and reliability in modern aerospace technology and modern defense equipment, the research on MEMS capacitive pressure sensors has received high attention both domestically and internationally.

[0003] Ordinary capacitive pressure sensors typically employ a parallel plate capacitor structure, mainly composed of a movable plate and a fixed plate. When pressure is applied to the movable plate, the distance between the two plates changes, thereby changing the capacitance value. Pressure is measured by detecting the capacitance value. However, this type of sensor has drawbacks such as severe nonlinearity between input and output and low overload capacity.

[0004] In addition, there is a contact capacitive pressure sensing structure. The main feature of this structure is that during operation, as the external pressure increases, the upper pressure plate will contact the dielectric layer on the lower plate. At this time, the output capacitance value will show an approximately linear relationship with the pressure change, thereby improving the linearity of ordinary capacitive pressure sensors to a certain extent. However, its sensitivity is relatively low, and its linearity and linear response range also need to be further improved. Summary of the Invention

[0005] The present invention addresses the above-mentioned problems by providing a high-performance capacitive pressure-sensitive chip.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: the present invention includes a substrate, characterized in that a pressure-sensitive lower electrode plate is disposed on the substrate, a pressure-sensitive upper electrode plate is disposed above the lower electrode plate, and a cavity is disposed between the upper electrode plate and the lower electrode plate.

[0007] As a preferred embodiment, the substrate described in this invention is a monocrystalline silicon, polycrystalline silicon, glass, or ceramic substrate.

[0008] As another preferred embodiment, the substrate of the present invention is made of glass.

[0009] As another preferred embodiment, the substrate of the present invention is provided with a pressure inlet channel or a pressure inlet chamber.

[0010] As another preferred embodiment, the pressure-sensitive lower electrode plate of the present invention is provided with a dielectric layer.

[0011] As another preferred embodiment, the cavity described in this invention is a sealed cavity.

[0012] As another preferred embodiment, the upper and lower electrode plates of the present invention are connected to an external circuit via solder joints and metal leads or solder joints.

[0013] As another preferred embodiment, the lower end of the substrate described in this invention is provided with a pad.

[0014] As another preferred embodiment, the substrate of the present invention is an annular substrate with an open center.

[0015] Secondly, the substrate with the central opening described in this invention is provided with a slot that allows the chip to be suspended and the lower electrode plate to sense pressure.

[0016] In addition, the card slot described in this invention is located at the lower outer periphery or the middle outer periphery of the base.

[0017] The beneficial effects of this invention.

[0018] This invention proposes a dual-moving-plate capacitive pressure-sensitive structure, where both the upper and lower plates are pressure-sensitive and movable. When external pressure is present, both plates deform simultaneously, creating a dual-moving effect. The capacitance between the plates changes, converting the pressure signal into an electrical signal output. As the pressure increases, the upper and lower plates come into contact, and the contact area changes at a near-constant rate, faster than in ordinary contact capacitive pressure-sensitive structures. Therefore, this pressure-sensitive chip exhibits higher sensitivity and superior output characteristics, improving sensor performance and making it particularly suitable for developing micro-range pressure sensors. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the following description.

[0020] Figure 1 This is a schematic diagram of the annular base and pad structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the card slot structure on the base of the present invention.

[0022] In the figure, 1 is the substrate, 2 is the dielectric layer, 3 is the lower electrode plate, 4 is the upper electrode plate, 5 is the dielectric layer, 8 is the pad, 9 is the cavity, 10 is the slot, and 11 is the pressure inlet chamber. Detailed Implementation

[0023] As shown in the figure, the present invention includes a base 1, a pressure-sensitive lower electrode plate 3 disposed on the base 1, a pressure-sensitive upper electrode plate 4 disposed above the lower electrode plate 3, and a cavity 9 disposed between the upper electrode plate 4 and the lower electrode plate 3.

[0024] The lower electrode plate 3 and the upper electrode plate 4 set on the substrate 1 are both pressure-sensitive movable structures. When there is external pressure, the upper electrode plate 4 and the lower electrode plate 3 will be deformed simultaneously under pressure, forming a double-movement effect, which causes the capacitance value between the two electrodes to change, thereby converting the pressure signal into an electrical signal output.

[0025] The substrate 1 can be a single-crystal silicon substrate, glass, or other materials.

[0026] A dielectric layer 5 is provided on the pressure-sensitive lower electrode plate 3. When there is external pressure, the upper and lower electrodes will be deformed simultaneously under pressure, forming a double-action effect; as the pressure continues to increase, the dielectric layer 5 on the upper electrode plate 4 and the lower electrode plate 3 come into contact with each other.

[0027] The cavity 9 is a sealed cavity.

[0028] The upper electrode plate 4 and the lower electrode plate 3 are connected to an external circuit via solder joints and metal leads or solder joints. The upper electrode plate 4 and the lower electrode plate 3 can be connected to an external circuit to form a pressure detection circuit, which converts the pressure signal into an electrical signal for output.

[0029] Below the pressure-sensitive lower electrode plate 3 is the pressure inlet chamber 11.

[0030] like Figure 1 As shown, a pad 8 is provided at the lower end of the substrate 1. The pad 8 raises the substrate 1 to a certain height, so that there is a gap between the lower end surface of the substrate 1 and the upper end surface of the circuit board. The pad 8 is not annular; there can be multiple pads 8 arranged circumferentially, and there is a pressure channel between adjacent pads 8.

[0031] like Figure 2 As shown, the annular base 1 with the central opening is provided with a slot 10 that allows the chip to be suspended and the lower electrode plate 3 to sense pressure.

[0032] The slot 10 is located at the lower outer periphery of the base 1.

[0033] The upper and lower pressure-sensitive plates of this invention can be designed in any desired shape, such as square, rectangle, circle, ring, etc.

[0034] A dielectric layer 2 is provided on the lower electrode plate 3 and the upper electrode plate 4. The silicon dioxide 2 serves as insulation and protection.

[0035] As shown in the figure, both the upper and lower electrode plates of this invention are pressure-sensitive movable structures. The lower electrode plate 3 can be set on the base 1 and is suspended and movable relative to the base 1. Both the upper and lower electrode plates are pressure-sensitive at the same time. The upper and lower electrode plates 3 are connected to the external circuit through pressure welding points and metal leads to convert the pressure signal into an electrical signal output.

[0036] When external pressure is present, both the upper and lower plates are simultaneously subjected to pressure, causing them to bend and change the distance between them, thus altering the capacitance. When the pressure exceeds a certain value, i.e., the contact pressure, the upper plate 4 begins to contact the dielectric layer 5 on the lower plate 3. During this process, the contact area increases at a near-constant rate, causing the contact capacitance to quickly become much larger than the non-contact capacitance, and the measured capacitance is primarily based on the contact capacitance. Therefore, within this pressure range, the sensor exhibits superior linearity and a higher output capacitance, improving its performance.

[0037] The upper and lower pressure-sensitive plates can be made of diaphragms of any shape.

[0038] The dual-plate capacitive pressure-sensitive chip proposed in this invention can be used for pressure measurement in various fields such as consumer electronics, petrochemicals, automotive electronics, medical, aerospace, and defense.

[0039] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A capacitive pressure sensitive chip comprising a substrate, characterized in that A pressure sensing lower plate is arranged on the substrate, a pressure sensing upper plate is arranged above the lower plate, and a cavity is arranged between the upper plate and the lower plate; a pressure inlet chamber is arranged on the substrate; The substrate is a ring-shaped substrate with an open middle part; A clamping groove is arranged on the substrate with an open middle part, which can suspend the chip and make the lower plate sense pressure, and the clamping groove is arranged in the middle part of the outer periphery of the substrate; A dielectric layer is arranged on the pressure sensing lower plate; The cavity is a sealed cavity; The upper plate and the lower plate are connected with an external circuit through a pressure welding point and a metal lead or a pressure welding point; The pressure sensing lower plate is below the pressure inlet chamber; When external pressure exists, the upper plate and the lower plate are deformed by the pressure at the same time, forming a double-acting effect, so that the capacitance value between the two plates changes, thereby converting the pressure signal into an electrical signal output; The upper plate and the lower plate are connected with an external circuit through a pressure welding point and a metal lead or a pressure welding point to form a pressure detection circuit, which converts the pressure signal into an electrical signal output; The upper and lower pressure sensing plates are ring-shaped; When external pressure exists, the upper and lower plates are subjected to pressure at the same time, the two plates are deformed and bent, the distance between the plates changes, and the capacitance value changes; when the pressure is greater than a certain pressure value, i.e. contact pressure, the upper plate starts to contact the dielectric layer on the lower plate, and in this process, the contact area increases, so that the contact capacitance value is much larger than the non-contact capacitance value, and the measurement capacitance is mainly the contact capacitance; within this pressure range, the sensor exhibits superior linearity and higher output capacitance value, improving the performance of the sensor; The upper and lower pressure sensing plates adopt a diaphragm.

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