Capacitive pressure sensitive chip

Abstract

The application discloses a capacitive pressure-sensitive chip, and belongs to the technical field of micro electro mechanical systems (MEMS), 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 pressure-sensing lower plate, and a cavity is arranged between the pressure-sensing upper plate and the pressure-sensing lower plate; and a lower plate through hole for connecting the pressure-sensing lower plate with a pressure cavity below the pressure-sensing lower plate is arranged on the pressure-sensing 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; a lower electrode plate through hole is disposed on the lower electrode plate to connect the outside world with the pressure cavity below the pressure-sensitive lower electrode plate.

[0007] As a preferred embodiment, the substrate described in this invention is a single-crystal silicon substrate.

[0008] As another preferred embodiment, the upper electrode plate of the present invention is provided with an upper electrode plate through hole corresponding to the through hole of the lower electrode plate (the through hole can penetrate the upper and lower electrode plates, so that the outside world is connected to the pressure chamber below the pressure-sensitive lower electrode plate).

[0009] As another preferred embodiment, the pressure-sensitive lower electrode plate of the present invention is provided with a dielectric layer.

[0010] As another preferred embodiment, the cavity described in this invention is a sealed cavity.

[0011] 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.

[0012] As another preferred embodiment, the pressure chamber is located below the pressure-sensitive lower electrode plate of the present invention.

[0013] As another preferred embodiment, the through holes of the present invention are disposed on both sides of the cavity.

[0014] As another preferred embodiment, the substrate of the present invention is an annular substrate with an opening in the middle;

[0015] Alternatively, a groove may be provided at the upper middle part of the substrate.

[0016] As another preferred embodiment, a pad is provided at the lower end of the substrate of the present invention.

[0017] Secondly, the annular substrate with a central opening in the present invention is provided with a slot that allows the chip to be suspended and the lower electrode plate to sense pressure.

[0018] In addition, the card slot described in this invention is located at the lower outer periphery of the substrate.

[0019] The beneficial effects of this invention.

[0020] 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

[0021] 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.

[0022] Figure 1 This is a schematic diagram of the present invention, which features through-holes and uses a ring-shaped substrate structure.

[0023] Figure 2 This is a schematic diagram of the present invention, which features a through-hole and a grooved substrate structure.

[0024] Figure 3 This is a schematic diagram of the structure of the present invention, which features through holes, an annular substrate, and pads (the through holes and pads allow the upper and lower plates to better sense pressure, and the pads at the bottom raise the structure so that the lower plate can directly contact the external pressure).

[0025] Figure 4 This is a simulation diagram of the present invention.

[0026] In the figure, 1 is the substrate, 2 is silicon dioxide (silicon dioxide is used as a dielectric layer, which can also be silicon nitride), 3 is the lower electrode plate, 4 is the upper electrode plate, 5 is the dielectric layer, 6 is the through hole, 7 is the groove, 8 is the pad, 9 is the cavity, 10 is the slot, and 11 is the pressure chamber. Detailed Implementation

[0027] As shown in the figure, the present invention includes a substrate 1, a pressure-sensitive lower electrode plate 3 disposed on the substrate 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.

[0028] The lower electrode 3 and the upper electrode 4 disposed on the silicon substrate 1 are both pressure-sensitive movable structures. When there is external pressure, the upper electrode 4 and the lower electrode 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.

[0029] The substrate 1 is a single-crystal silicon substrate.

[0030] 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.

[0031] The cavity 9 is a sealed cavity.

[0032] 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.

[0033] The pressure chamber 11 is located below the pressure-sensitive lower electrode plate 3.

[0034] like Figure 1 , 2 As shown in Figure 3, the lower electrode plate 3 is provided with a through hole 6 that connects the outside world with the pressure chamber 11 below the pressure-sensitive lower electrode plate 3. The through hole 6 serves as a pressure inlet channel, through which external pressure can be applied to the lower electrode plate 3 via the pressure chamber 11.

[0035] After the chip is mounted on the circuit board, the lower surface of substrate 1 is completely aligned with the upper surface of the circuit board, such as... Figure 1 As shown, if the through hole 6 is not provided, the pressure chamber 11 is not connected to the outside world because the lower end of the pressure chamber 11 is closed by the upper surface of the circuit board.

[0036] like Figure 2 After the chip is mounted on the circuit board, the lower surface of substrate 1 is completely aligned with the upper surface of the circuit board, as shown. Figure 1 As shown, if the through hole 6 is not provided, the groove 7 chamber is not connected to the outside world because the lower end of the groove 7 chamber is closed by the upper surface of the circuit board.

[0037] like Figure 3 After the chip is mounted on the circuit board, the lower surface of substrate 1 is completely aligned with the upper surface of the circuit board, as shown. Figure 1 As shown, the pressure chamber 11 is connected to the outside through the through hole 6. The chip is raised by setting the pad 8 so that the pressure chamber 11 is directly connected to the outside. The pressure-sensing lower electrode 3 directly senses the pressure, just like the upper electrode 4.

[0038] The through holes 6 are located on both sides of the cavity 9.

[0039] The substrate 1 is a substrate with an open center; or the upper part of the center of the substrate 1 is provided with a groove 7 (e.g., Figure 2 (As shown). The upper electrode 4 and the lower electrode 3 form a sealed cavity 9. The lower electrode 3 is located between the upper electrode 4 and the groove 7 of the substrate 1, and is suspended and movable relative to the silicon substrate 1. External pressure can be applied to the lower electrode 3 through the pressure inlet channel and the groove 7.

[0040] like Figure 3 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.

[0041] The upper and lower pressure-sensitive plates of this invention can be designed in any desired shape, such as square, rectangle, circle, ring, etc.

[0042] Silicon dioxide 2 is disposed between the substrate 1 and the lower electrode plate 3, silicon dioxide 2 is disposed on the lower electrode plate 3, and silicon dioxide 2 is disposed on the upper electrode plate 4. The silicon dioxide 2 serves as insulation and protection.

[0043] like Figure 2As shown, both the upper and lower electrode plates of this invention are pressure-sensitive movable structures. The lower electrode plate 3 can be disposed on the monocrystalline silicon substrate 1 with the groove 7 etched on it. The lower electrode plate 3 is suspended and movable relative to the monocrystalline silicon substrate 1. External pressure can be applied to the lower electrode plate 3 through the pressure inlet channel and the groove 7. The upper and lower electrode plates are connected to the external circuit through the pressure bonding point and the metal lead wire to convert the pressure signal into an electrical signal output.

[0044] 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.

[0045] The upper and lower pressure-sensitive plates can be circular diaphragms or any shape.

[0046] like Figure 4 As shown, the range of this simulation diagram is 75KP--115KP, the electrode thickness is 3um, the electrode spacing is 0.5um, and the upper and lower electrodes are in contact at 75KP. The output characteristic curve of this range is very good, almost a straight line.

[0047] 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, home appliances, and national defense.

[0048] It is understood that the above detailed description of the present invention is for illustrative purposes only and is not intended to limit 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 effects; as long as the usage requirements are met, they are all within the protection scope of the present invention. This structure can also be applied to silicon microphones, accelerometers, etc.

Claims

1. A capacitive pressure-sensitive chip, comprising a substrate, characterized in that... A pressure-sensitive lower electrode plate is disposed on the substrate, and a pressure-sensitive upper electrode plate is disposed above the lower electrode plate. A cavity is disposed between the upper electrode plate and the lower electrode plate. A lower electrode plate through hole is disposed on the lower electrode plate to connect the outside world with the pressure cavity below the pressure-sensitive lower electrode plate. The substrate is an annular substrate with an opening in the middle; The annular substrate (1) with the central opening is provided with a slot that allows the chip to be suspended and the lower electrode plate (3) to be pressure-sensitive, or a pad is provided at the lower end of the substrate. The slot is located at the lower outer periphery of the substrate; Silicon dioxide (2) is disposed between the substrate (1) and the lower electrode plate (3), silicon dioxide (2) is disposed on the lower electrode plate (3), and silicon dioxide (2) is disposed on the upper electrode plate (4). The lateral dimension of the lower electrode plate (3) is larger than that of the upper electrode plate (4). The upper electrode plate (4) is located above the middle of the lower electrode plate (3). A recess is provided in the middle of the lower electrode plate (3), and the dielectric layer (5) is located in the recess. Silica (2) covers the upper end and outer periphery of the lower electrode plate (3) except for the recess, and silica (2) covers the upper end and outer periphery of the upper electrode plate (4). Through holes (6) are located on the outer periphery of the recess. There are multiple through holes (6), and the through holes (6) are vertical through holes. The pad (8) is not a ring shape. The pad (8) is arranged in multiple circumferential directions, and there is a pressure channel between adjacent pads (8).

2. The capacitive pressure-sensitive chip according to claim 1, characterized in that... The substrate is a single-crystal silicon substrate.

3. The capacitive pressure-sensitive chip according to claim 1, characterized in that... The upper electrode plate is provided with an upper electrode plate through hole corresponding to the lower electrode plate through hole.

4. The capacitive pressure-sensitive chip according to claim 1, characterized in that... A dielectric layer is provided on the pressure-sensitive lower electrode plate.

5. A capacitive pressure-sensitive chip according to claim 1, characterized in that... The cavity is a sealed cavity.

6. A capacitive pressure-sensitive chip according to claim 1, characterized in that... The upper and lower electrode plates are connected to the external circuit via solder joints and metal leads or solder joints.

7. A capacitive pressure-sensitive chip according to claim 1, characterized in that... The through holes are located on both sides of the cavity.

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