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Four-folding beam variable area differential capacitance structure micro-acceleration sensor and manufacture method thereof

A technology of acceleration sensor and differential capacitance, applied in the field of micro-acceleration sensor and its preparation, can solve the problems of small variation of differential capacitance, difficult processing circuit, etc., and achieve the effects of increasing sensitivity, improving anti-interference ability, and solving nonlinear problems

Inactive Publication Date: 2010-11-10
JILIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The capacitance change of the variable gap differential capacitance acceleration sensor is nonlinear, and the method of limiting the displacement of the mass block is usually used to approximate the linear relationship. As a result, the change of the differential capacitance is very small, which brings great difficulties to the subsequent processing circuit.

Method used

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  • Four-folding beam variable area differential capacitance structure micro-acceleration sensor and manufacture method thereof
  • Four-folding beam variable area differential capacitance structure micro-acceleration sensor and manufacture method thereof
  • Four-folding beam variable area differential capacitance structure micro-acceleration sensor and manufacture method thereof

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Effect test

Embodiment 1

[0028] The structural parameters of the micro-acceleration sensor of the present invention are shown in Table 1. 20 upper electrode arrays are made on the lower surface of the movable mass, and the corresponding finger-shaped lower electrodes adopt 20 pairs of electrode structures, thereby forming 20 identical capacitors in parallel.

[0029] Table 1: Parameters of mass and folded beam

[0030]

[0031]

[0032] After the structural size design of the device is completed, the following method can be used to fabricate the device.

[0033] A: Fabrication of the lower electrode

[0034] 1) Use Pyrex7740 with a thickness of 200 microns # borosilicate glass;

[0035] 2) Form a photoresist pattern complementary to the lower electrode structure to be made on the glass through a photolithography process, and then sputter a 50nm gold layer on the photoresist as the lower electrode material;

[0036] 3) The photoresist and the gold layer on it are removed by using the strippi...

Embodiment 2

[0044] The overall scheme of the detection circuit is as follows Figure 5 As shown, the carrier generator provides a stable sine wave for the whole circuit, and the differential capacitance of the acceleration sensor (C 1 、C 2 ) is connected to the input terminal of the charge amplifier, and the charge amplifier circuit (such as Figure 6Shown) converts a small differential capacitance change into a voltage change. Since the differential capacitance change is very small, the voltage change is also very weak. For the convenience of subsequent circuit detection, the signal is amplified by a DC amplifier, but the signal at this time still contains high-frequency noise and other interference, and the high-Q band-pass filter filters out the interference to make the waveform better. The signal at this time and the signal after the phase-shifting circuit are used as the input of the phase-sensitive demodulation circuit. When the two signals are inverting or in-phase at the same fr...

Embodiment 3

[0050] Charge amplification circuit design: such as Figure 6 Shown, C 1 、C 2 are the two differential capacitors of the accelerometer, C 3 is the feedback capacitor of the op amp, C 4 The role is to remove noise interference, R 1 and the feedback capacitor C 3 in parallel.

[0051] After selecting the relevant circuit component parameters, the circuit is analyzed and the equations are obtained:

[0052] V ′ - V o 1 s C 3 / / R 1 ...

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Abstract

The invention belongs to the field of a micro electro mechanical system, relating to a four-folding beam variable area differential capacitance structure micro-acceleration sensor and a manufacture method thereof. The sensor consists of a movable mass block, paired spring folding beams, an inserting finger-shaped lower electrode and a micro-acceleration sensor outer frame, wherein the front end and the back end of the movable mass block are connected with the acceleration sensor outer frame through the spring folding beams on the action direction of the outer load; the movable mass block, the spring folding beams and the acceleration sensor outer frame are formed into an integral structure; the lower surface of the movable mass block is provided with an upper electrode; a certain gap is formed between the upper electrode and the inserting finger-shaped lower electrode to be formed into a plate differential capacitor; and the upper electrode is boned with the inserting finger-shaped lower electrode through the acceleration sensor outer frame. With the structure, the invention obviously solves the problem of the nonlinearity of the existing variable gap structure, is good for manufacturing follow-up detecting circuits, leads a vibration mode to be better separated, improves the anti-jamming capability of a device, and increases the sensitivity of the sensor.

Description

technical field [0001] The invention belongs to the field of micro-electro-mechanical systems, and in particular relates to a micro-acceleration sensor with four folded beams and a variable-area differential capacitance structure and a preparation method thereof. Background technique [0002] Sensors based on MEMS technology have the advantages of small size, light weight, fast response, high sensitivity, low cost, and easy production, and have been widely used in many fields in recent years. The capacitive acceleration sensor has the advantages of high sensitivity, wide dynamic range, small temperature effect, good damping characteristics, simple structure and small size, so it is currently the most researched and applied silicon micro-acceleration sensor. [0003] The capacitance change of the variable-gap differential capacitance acceleration sensor is nonlinear, and the method of limiting the displacement of the mass block is usually used to approximate the linear relati...

Claims

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Application Information

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IPC IPC(8): G01P15/125B81B3/00B81C1/00
Inventor 董玮周敬然陈维友张歆东刘彩霞阮圣平郭文滨沈亮
Owner JILIN UNIV
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