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MEMS pressure sensor based on phase detection principle and preparation method thereof

A pressure sensor and phase detection technology, which is used in fluid pressure measurement, force measurement, piezoelectric device/electrostrictive device, etc. using capacitance change. Advanced problems, to achieve the effect of saving chip area, low price, and improving integration

Active Publication Date: 2021-09-07
NANJING GAOHUA TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The piezoresistive pressure sensor is based on the principle of piezoresistive effect of semiconductor materials (such as polysilicon, etc.). The principle of variable quantity has high sensitivity, but poor linearity and is susceptible to interference; piezoelectric pressure sensors are based on the principle of piezoelectric effect of materials (such as PZT, AlN, etc.), and their response speed is fast, but piezoelectric materials The preparation is complicated, and some parts are difficult to be compatible with the standard process; the resonant pressure sensor is based on the principle that the resonant frequency of the structure changes with the pressure, and its sensitivity is high, but because the pressure change has little change in the frequency offset, its resolution is not high

Method used

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  • MEMS pressure sensor based on phase detection principle and preparation method thereof
  • MEMS pressure sensor based on phase detection principle and preparation method thereof
  • MEMS pressure sensor based on phase detection principle and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0031] This embodiment provides a MEMS pressure sensor based on the principle of phase detection, such as Figure 1 ~ Figure 3 As shown, it includes: CPW transmission line, substrate 13, groove 131, buffer medium layer 132, MEMS film 2 and MEMS beam 3; the CPW transmission line is arranged on the substrate 13, and the substrate 13 is provided with concave Groove 131, the MEMS beam 3 is arranged in the groove 131; the MEMS film 2 and the groove 131 form a closed cavity, and the substrate 13 is made of high-resistance silicon with a resistivity greater than 1 kΩ·cm.

[0032] The CPW transmission line includes a CPW signal line 1 located in the middle of the substrate 13 and two CPW ground lines 12 located on both sides of the CPW signal line 1, the CPW signal line 1 and the CPW ground line 12 parallel to each other.

[0033] The groove 131 is located directly below the middle portion of the CPW signal line 1 . The groove 131 is a U-shaped groove, and the axis of the groove 131...

Embodiment 2

[0038] The present invention also provides the preparation method of the above MEMS pressure sensor based on the phase detection principle, such as Figure 5-11 shown, including the following steps:

[0039] S10 prepares the Si substrate 13, the substrate is for example made of high-resistance silicon, its resistivity is greater than 1kΩ·cm, and a groove 131 is etched on the substrate, the depth of the groove is for example 1-50 μm, and then A layer of buffer dielectric layer 132 is grown on the substrate by thermal oxidation, such as Figure 6 shown.

[0040] S20 sequentially pass photolithography, evaporation, and stripping on the buffer medium layer to obtain MEMS beams and CPW ground wires; as Figure 7 As shown; wherein, the MEMS beam 3 and the CPW ground wire 12 are prepared from the same material in the same process step, and are connected to each other.

[0041] S30 deposits and photoetches the PSG sacrificial layer, retains the PSG sacrificial layer inside the groo...

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Abstract

The invention provides an MEMS pressure sensor based on a phase detection principle and a preparation method thereof, and the sensor comprises: a CPW transmission line which is disposed on a substrate, wherein the CPW transmission line comprises a CPW signal line and CPW ground lines located at two sides of the CPW signal line, the CPW signal line is parallel to the CPW ground lines, and a groove is disposed on the substrate and located below the CPW signal line; an MEMS beam which is positioned on the bottom surface of the groove and two side surfaces close to the CPW ground wire, is in an inverted arch bridge shape and is connected with the CPW ground wire; and an MEMS thin film which is located above the groove and makes contact with the bottom face of the CPW signal line, wherein the two ends of the MEMS thin film are arranged on the CPW ground line, and a closed cavity is formed by the MEMS thin film and the groove. The closed cavity is used for sensing the pressure intensity of the external environment, and the phase difference of the RF signal before and after transmission on the CPW transmission line changes, so that the environment pressure intensity can be obtained by measuring the phase of the RF signal.

Description

technical field [0001] The invention relates to the technical field of radio frequency microelectromechanical systems (RF MEMS), in particular to a MEMS pressure sensor based on the principle of phase detection and a preparation method. Background technique [0002] The pressure sensor can sense the pressure signal and convert the pressure signal into an easy-to-measure output electrical signal according to certain rules. It is widely used in automotive electronics, automatic control, aerospace, biomedical, environmental monitoring and other fields, and is one of the commonly used sensors in the industry. With the development of MEMS technology, pressure sensors prepared by MEMS micromachining technology have the advantages of miniaturization, low power consumption, and batch production; according to different pressure test types, pressure sensors can be divided into gauge pressure, differential pressure and absolute pressure. According to different pressure test principles...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B81B3/00B81B7/02B81C1/00G01L1/14G01L9/12
CPCB81B3/0021B81B7/02B81C1/0015B81C1/00158G01L1/14G01L9/12B81B2201/0264B81B2203/0118
Inventor 李维平兰之康邵文东
Owner NANJING GAOHUA TECH
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