CN101526394A - Low-frequency vibration measuring device - Google Patents
Low-frequency vibration measuring device Download PDFInfo
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- CN101526394A CN101526394A CN200910106373A CN200910106373A CN101526394A CN 101526394 A CN101526394 A CN 101526394A CN 200910106373 A CN200910106373 A CN 200910106373A CN 200910106373 A CN200910106373 A CN 200910106373A CN 101526394 A CN101526394 A CN 101526394A
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Abstract
The invention relates to a low-frequency vibration measuring device, comprising a vibration sensor and a CMOS chip, the vibration sensor is integrated on the CMOS chip, the vibration sensor is a micro electro mechanical system (MEMS) containing a sensing element; wherein, the sensing element comprises an FET containing an air gate dielectric and a floating gate, an vibration-inducing mass block containing a metal gate is installed opposite to the floating gate, the vibration of the mass block causes change of the coupling capacitance between the floating gate and the metal gate, and causes drain current change of the FET. Vibration information can be obtained by measuring current, in addition, the coupling capacitance between the floating gate and drain is used to increase transconductance, thus improving sensitivity and realizing the purpose of measuring low-frequency vibration.
Description
[technical field]
The present invention relates to a kind of vibration measurement device, especially relate to a kind of low-frequency vibration measuring device.
[background technology]
In some field, very low as the frequency of vibration such as large rotating machine device, heavy construction structure, skyscraper, bridge dam, generally require surveying instrument can measure low-frequency vibration about 0.5Hz.For low frequency and even ultra-low frequency signal (≤0.1Hz) be the difficult point of many domestic and international measurement and analysis instruments, for≤0.01Hz even to the extremely low frequency signal of 0.001Hz, their Measurement and analysis almost is a blank.Low-frequency vibration is monitored and fault diagnosis, all need high sensitivity and high reliability to satisfy the needs of security.The vibration of genset as monitoring is given security for the genset safe operation.Bridge self-vibration characteristic test is for determining that the bridge running status provides foundation, when bridge load operation all the year round, or suffers accidental impact, and the duty of bridge might change.The bridge self-vibration characteristic also may cause influencing vehicle and bridge resonates.Along with the development of exploration engineering, the demand that is used to accept the wave detector of seismic signal grows with each passing day, and has proposed higher technical requirement.At present, the frequency effective range of the vibration transducer that generally uses in seismic prospecting is between 5Hz～500Hz, the following seismic signal of 5Hz is difficult to accurately measure, and these low-frequency information are very useful to the inverting stratal configuration, but seismoreceiver never has big breakthrough.Because such sensor can not get desirable original signal, has become one of main bottleneck of petroleum exploration.The maximum drawback of this class wave detector is exactly that sensitivity is low at present.The 2nd, the signal to noise ratio (S/N ratio) that low-frequency range is low.Because the vibration frequency about 1Hz has proposed harsh requirement to the low frequency characteristic of inertia-type sensor, yet such sensor is because the inherent shortcoming of its physical construction at present, at ultralow frequency range (1Hz and following), its output signal fully " flooding " is difficult to realize the accurate measurement to vibration parameters in noise.Therefore the detection of ultralow frequency absolute vibration is a great problem in engineering test field always.
[summary of the invention]
In view of this, be necessary to provide a kind of highly sensitive low-frequency vibration measuring device that has.
A kind of low-frequency vibration measuring device, involving vibrations sensor and CMOS chip, described vibration transducer is integrated on the described CMOS chip, described vibration transducer comprises sensing unit, described sensing unit comprises the field effect transistor that contains floating boom and has embedded metal or polycrystalline silicon material is used for the mass of induction vibration as grid, described floating boom embeds in the dielectric layer of CMOS chip, described mass places the opening of CMOS chip medium layer, and corresponding setting with field effect transistor, be the silica medium layer of air dielectric layer and CMOS chip between described mass and the field effect transistor, make grid and floating boom be oppositely arranged.
The overlap capacitance of utilizing floating boom and drain electrode to constitute, and the mutual conductance that increases field effect transistor; Grid changes the coupling capacitance of grid and floating boom formation with the vibration of mass, and then changes the output current size of field effect transistor, thereby can measure low-frequency vibration, reaches highly sensitive effect.
In a preferred embodiment, be provided with cantilever in the described dielectric layer, described mass places on the described cantilever, makes the mass can free vibration.
In a preferred embodiment, described field effect transistor is thick oxygen transistor, can improve the ratio of the coupling capacitance of floating boom and drain electrode in total capacitance, thereby further improves sensitivity.
In a preferred embodiment, described field effect transistor is the nature field effect transistor, and described natural field effect transistor directly is built on the substrate, and its channel doping concentration is 3 * 10
15/ cm
3-1 * 10
16/ cm
3Low doping content has reduced impurity scattering, has improved signal to noise ratio (S/N ratio).Because grid is unsettled, the low-frequency noise that causes thereby the ditch that the gate oxidation layer charge fluctuation that reduces unit area causes is led the fluctuation of mobility, and reduced the noise that gate leakage current and sub-threshold leakage current cause, thereby improved output current and keep low noise.
[description of drawings]
Fig. 1 is the structural representation of low-frequency vibration measuring device;
Fig. 2 is the structural representation of measurement mechanism groundwork part;
Fig. 3 is the equivalent circuit diagram of structure shown in Figure 2;
Fig. 4 is vibration displacement-output current figure;
Fig. 5 is the amplitude versus frequency characte figure of 0.05g inertial acceleration lower sensor;
Fig. 6 is the noise-frequency comparison diagram of nature field effect transistor and conventional field effect transistor.
Be further detailed below in conjunction with accompanying drawing.
[embodiment]
A kind of low-frequency vibration measuring device, involving vibrations sensor and CMOS chip, described vibration transducer is integrated on the same CMOS chip, described vibration transducer is the microelectromechanical systems (MEMS) that comprises sensing unit, wherein sensing unit is that grid is floated, and promptly has the field effect transistor of floating boom, utilizes the coupling capacitance of floating boom and drain electrode to increase mutual conductance, thereby raising sensitivity reaches the purpose of measuring vibrations.
At first, in layout design, select 0.18 μ m mixed signal technology for use, the thick oxygen field effect transistor of 3.3V and natural field effect transistor (Native MOS) in SPICE technology library Modeling and Design.Field effect transistor breadth length ratio W/L is 208, and field effect transistor grid length is 1.2 μ m, grid width 250 μ m.Utilize CMOS technology to realize then.Do not have mask dry etching and wet etching after the CMOS flow and discharge microstructure.
The CMOS chip is through dry etching and wet corrosion technique formation structure as shown in Figure 1.Outer layer metal film 1 covers on the silica medium layer 21 of CMOS chip, is integrated on the CMOS chip as the field effect transistor 3 of the sensing unit of microelectromechanical systems (MEMS).Wherein field effect transistor 3 comprises the thick oxygen gate oxide 34 between floating boom 31, source electrode (not indicating), drain electrode 32, substrate 33 and floating boom 31 and the substrate 33.Floating boom 31 places the silica medium layer 21 of described CMOS chip.
Also be provided with cantilever 7 in dielectric layer 21, mass 5 places on the cantilever 7, and mass 5 can free vibration on cantilever 7.
The synoptic diagram of the groundwork of present embodiment medium and low frequency vibration measurement device part as shown in Figure 2, the floating boom 31 of field effect transistor does not join with other interconnection line, its top is provided with the mass 5 that comprises metal gates 4 at interval, mass 5 can up-down vibration.Its equivalent working circuit diagram as shown in Figure 3, the principle of work of measurement is as follows:
In conjunction with Fig. 2, on metal gates 4, add a clock pulse signal voltage of CMOS chip, mass 5 vibrations make metal gates 4 and floating boom 31 couplings form variable capacitance C
FgVariable capacitance C
FgCapacitor C with the thick oxygen gate oxide 34 of field effect transistor
OxPolyphone.Because the voltage that the clock pulse signal frequency far above the vibration frequency of vibration transducer mass 5, is added on the metal gates 4 is given variable capacitance C
FgWith capacitor C
OxCharging, and reach equilibrium state rapidly.In a certain moment of vibration, can think variable capacitance C
FgIt is fixed capacity.Because also there is coupling capacitance C in floating boom 31 with drain electrode 32
Fd, when distinguishing making alive V in drain electrode 32 and metal gates 4
DAnd V
GThe time, by draining 32 and the coupling capacitance C of floating boom 31
FdAnd variable capacitance C
FgOn floating boom 31, induce noble potential.Mass 5 is at arbitrary moment in per 1/4 cycle of its vibration, variable capacitance C
FgIt is constant capacitance that charging just reaches after the balance having different, so different induced electric fields changes the electrical conductance of the following channel region of floating boom 31.And then drain current changes, and obtains vibration signal according to the drain current that measures.
In the present embodiment, the field effect transistor of selecting for use is thick oxygen transistor, since thick oxygen characteristics of transistor, the coupling capacitance C of floating boom and drain electrode
FdRatio regular meeting in total capacitance is bigger than the transistorized ratio of other types, increases C
FdRatio in total capacitance can make the change in voltage on the floating boom obvious, thereby the electric conductivity of raceway groove in the field effect transistor is changed, and improves the sensitivity of field effect transistor in measurement, improves the effect of measuring low-frequency vibration.
Utilize the HSPICE Simulation result as shown in Figure 4, when the movable clearance of the grid of mass and the coupling capacitance of floating boom is 0～100nm, the sensing unit that single field effect transistor constitutes, the drain electrode output current that measures is between 3.8mA～6.0mA.And in Fig. 5, under the inertial acceleration of vibration transducer inertial force, resolution is the 0.05g/1.5 dust, so susceptibility reaches 3.7 μ A/0.05g.。
In addition, field effect transistor is nature field effect transistor (Native MOS), and as shown in Figure 2, natural field effect transistor directly is built on the lightly doped P type substrate, do not need extra mask plate with the complete compatibility of the commercial CMOS technology of standard, the doping content of its raceway groove is 3 * 10
15/ cm
3-1 * 10
16/ cm
3, having the field effect transistor of this doping content, its threshold voltage approaches zero volt, thereby improves output current and keep low noise and eliminated the noise that trap/the body mutual conductance causes.Utilize the HSPICE Simulation result as shown in Figure 6, as can be seen from the figure, natural field effect transistor has extremely low noise with respect to the metal-oxide-semiconductor of routine.
In Fig. 1, also can see, the space that grid 4 and floating boom are 31 is divided into two parts, be that a part is an air layer 6, a part is the dielectric layer 21 of CMOS chip, the benefit of this kind structure is can avoid because of electrostatic force produces the adhesive phenomenon above causing mass sharply to move down after the elastic restoring force, and causing can't return.
The above embodiment has only expressed one embodiment of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.
Claims (4)
1. low-frequency vibration measuring device, involving vibrations sensor and CMOS chip, it is characterized in that, described vibration transducer is integrated on the described CMOS chip, described vibration transducer comprises sensing unit, described sensing unit comprises the field effect transistor that contains floating boom and has embedded metal or polycrystalline silicon material is used for the mass of induction vibration as grid, described floating boom embeds in the dielectric layer of CMOS chip, described mass places the opening of CMOS chip medium layer, and corresponding setting with field effect transistor, be the silica medium layer of air dielectric layer and CMOS chip between described mass and the field effect transistor, make grid and floating boom be oppositely arranged.
2. low-frequency vibration measuring device as claimed in claim 1 is characterized in that, is provided with cantilever in the described dielectric layer, and described mass places on the described cantilever, makes the mass can free vibration.
3. low-frequency vibration measuring device as claimed in claim 1 is characterized in that, described field effect transistor is thick oxygen transistor.
4. low-frequency vibration measuring device as claimed in claim 1 is characterized in that, described field effect transistor is the nature field effect transistor, and described natural field effect transistor directly is built on the substrate, and its channel doping concentration is 3 * 10
15/ cm
3-1 * 10
16/ cm
3
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009101063736A CN101526394B (en) | 2009-03-31 | 2009-03-31 | Low-frequency vibration measuring device |
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| CN2009101063736A CN101526394B (en) | 2009-03-31 | 2009-03-31 | Low-frequency vibration measuring device |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103033255A (en) * | 2012-12-13 | 2013-04-10 | 浙江大学 | Extraction device for relative motion capacity of low-frequency electromagnetic vibration generator system |
| CN103745941A (en) * | 2013-12-30 | 2014-04-23 | 上海新傲科技股份有限公司 | Electric performance test method for gate dielectric |
| CN108267220A (en) * | 2018-02-05 | 2018-07-10 | 山东理工大学 | A kind of piezoelectric vibration sensing device based on fet gate sensitlzing effect |
| CN111060192A (en) * | 2019-10-21 | 2020-04-24 | 张国基 | Calculation chip system for abnormal vibration of mechanical equipment |
-
2009
- 2009-03-31 CN CN2009101063736A patent/CN101526394B/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103033255A (en) * | 2012-12-13 | 2013-04-10 | 浙江大学 | Extraction device for relative motion capacity of low-frequency electromagnetic vibration generator system |
| CN103033255B (en) * | 2012-12-13 | 2014-12-10 | 浙江大学 | Extraction device for relative motion capacity of low-frequency electromagnetic vibration generator system |
| CN103745941A (en) * | 2013-12-30 | 2014-04-23 | 上海新傲科技股份有限公司 | Electric performance test method for gate dielectric |
| CN103745941B (en) * | 2013-12-30 | 2016-06-08 | 上海新傲科技股份有限公司 | The testing method of the electric property of gate medium |
| CN108267220A (en) * | 2018-02-05 | 2018-07-10 | 山东理工大学 | A kind of piezoelectric vibration sensing device based on fet gate sensitlzing effect |
| CN111060192A (en) * | 2019-10-21 | 2020-04-24 | 张国基 | Calculation chip system for abnormal vibration of mechanical equipment |
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| CN101526394B (en) | 2012-02-15 |
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Effective date of registration: 20230327 Address after: 519085 101, Building 5, Longyuan Smart Industrial Park, No. 2, Hagongda Road, Tangjiawan Town, High-tech Zone, Zhuhai City, Guangdong Province Patentee after: ZHUHAI INSTITUTE OF ADVANCED TECHNOLOGY CHINESE ACADEMY OF SCIENCES Co.,Ltd. Address before: 518067 Nanshan medical equipment Industrial Park, No. 1019 Nanhai Road, Shenzhen, Guangdong, Nanshan District 3A Patentee before: SHENZHEN INSTITUTES OF ADVANCED TECHNOLOGY |
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