CN1223859C - Micro mechanical acceleration sensor of high natural frequency and measuring range up to 2 million m/s2 - Google Patents
Micro mechanical acceleration sensor of high natural frequency and measuring range up to 2 million m/s2 Download PDFInfo
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- CN1223859C CN1223859C CN 02136742 CN02136742A CN1223859C CN 1223859 C CN1223859 C CN 1223859C CN 02136742 CN02136742 CN 02136742 CN 02136742 A CN02136742 A CN 02136742A CN 1223859 C CN1223859 C CN 1223859C
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Abstract
The present invention relates to a micro mechanical acceleration sensor with a high natural frequency and a measuring range up to 200 million m/s<2>. The present invention is characterized in that the present invention is composed of voltage dependent resistors, sensitive beams, an anchor area, a main beam, a quality block, transition structures and a lower cover plate, wherein each transition structure is arranged between the anchor area and each sensitive beam; the sensitive beams and the middle main beam are connected in series, and the main beam is positioned at the middle part of the structure of the present invention; the present invention realizes that the main beam has more than 3 times the length of each sensitive beam through each transition structure between the anchor area and each sensitive beam; the thickness of the transition structure is less than 1 micrometer than that of a substrate silicon chip, and the length of each transition structure is the length difference of the middle main beam and each sensitive beam; 4 sensitive beams are symmetrically distributed at both ends of the quality block; each voltage dependent resistor is designed into a single straight bar, four voltage dependent resistors are positioned at the junctures of the sensitive beams and the anchor area, and the other four voltage dependent resistors are positioned at the junctures of the sensitive beams and the quality block; a gap of 2 micrometers is arranged between the lower cover plate and the quality block. The natural frequency can reach more than 700kHz by the specific structure design.
Description
Technical field
The present invention relates to a kind of range and can reach 2,000,000 m/s
2The very little micromechanics piezoresistance type acceleration sensor of transversal effect of high natural frequency of extra-high-speed range, belong to the microelectromechanical systems field.
Background technology
Growing along with markets such as anti-locking system for car, guidance system, mechanical vibration monitoring, military fuses, the acceleration transducer demand more and more increases.Various micro-machine acceleration transducers constantly develop in the development, and wherein the research of silicon micro mechanical pressure resistance type and capacitive acceleration transducer has accounted for sizable part.
Piezoresistance type acceleration sensor is based on the semiconductor pressure resistance effect, promptly when the external world applies a certain acceleration, causes the relative displacement to substrate of mass and beam, causes the STRESS VARIATION on the beam.Because piezoresistive effect, the sensitive resistance value is corresponding on the beam changes, but utilizes suitable peripheral circuit that this variation is converted into measuring-signal, as voltage, electric current, just can set up output signal and by the relation between the measuring acceleration through calibration, thus the measurement acceleration.The research of piezoresistance type acceleration sensor is range (hundreds of m/s from present just
2-1 ten thousand m/s
2) to little range (as 10m/s
2About) and the extra-high-speed range (greater than ten thousand m/s
2) development.Design extra-high-speed measuring range acceleration sensor must be considered the bending strength of silicon because acceleration greatly the stress to the back rest to a certain degree may make the beam fracture, so should avoid that this thing happens.Thereby, should determine the measurement range of sensor according to the fracture strength of silicon, promptly the maximum stress on the chip should be less than the fracture strength of silicon during full scale.
Summary of the invention
Add the meter that hastens for any pressure resistance type, frequency and sensitivity are two most important parameter indexs.There is the conflicting of frequency and sensitivity in conventional high-range acceleration meter, and promptly then sensitivity is low for the frequency height, and frequency is low then highly sensitive.The object of the present invention is to provide a kind of range can reach 2,000,000 m/s
2Above micromechanics pressure resistance type extra-high-speed measuring range acceleration sensor by new structural design cleverly, can reach more than the 700kHz natural frequency of this sensor.
The objective of the invention is to realize by following manner.The micromechanics pressure resistance type extra-high-speed measuring range acceleration sensor that provides mainly is made up of seven parts such as transition structure between voltage dependent resistor (VDR), sensitive beam, anchor district, girder, mass, anchor district and the sensitive beam and lower covers.When acceleration, the relative matrix motion of mass causes sensitive beam to deform, thereby causes that the voltage dependent resistor (VDR) on the sensitive beam changes, and just knows the size of acceleration by peripheral testing circuit.Middle girder makes the design's frequency improve greatly on the one hand, has reduced transversal effect again dexterously.And because the reducing of sensitive beam size, the deformation energy of structure concentrates on this responsive part, so the raising greatly of frequency does not make sensitivity descend accordingly, has so just avoided both irreconcilable contradictions of conventional design.
Range provided by the invention can reach 2,000,000 m/s
2Above micromechanics piezoresistance type acceleration sensor architectural feature is:
1. Zhong Jian girder and sensitive beam are stacked position relation, and like this, when bearing extraneous acceleration, sensitive beam and middle girder come together to limit the motion of mass, thereby the natural frequency of this accelerometer is improved greatly.The width of girder is identical with base widths, the width of sensitive beam is less than the width of the girder of centre, the length of girder is more than 3 times of sensitive beam, and, girder is positioned at the middle part of sensor construction, guaranteed that like this girder does not meet with stresses substantially, thereby natural frequency can not cause the decline of sensitivity when improving.
2. the length of girder is more than 3 times of sensitive beam, is to realize that by the transition structure between anchor district and the sensitive beam thickness of this transition structure is only little 1 micron than the thickness of substrate silicon chip, and its length is the length difference of the length and the sensitive beam of middle girder.This transition structure is approximately the anchor district in the physical sense, and doing the time spent as acceleration does not have stress above it.
3. 4 sensitive beam are distributed in the two ends of mass symmetrically, can reduce the transversal effect of device unchangeably simultaneously at the sensitive beam stiffness coefficient.Sensitive beam thickness is 10 μ m-50 μ m, and its thickness is relevant with the range of sensor
With conventional piezoresistance type acceleration sensor sensitive resistance by the series connection of many rectangle straight line strip sheet resistances different be that the sensitive resistance that the present invention proposes is designed to single straight line strip, wide 10 μ m, wherein 4 intersections that are placed in sensitive beam and anchor district.
5. adopt the structure of lower cover, 2 microns gap is arranged between lower cover and the mass, this gap can make the air damping ratio approach about 0.7, can guarantee that like this this sensor has best bandwidth.
Range provided by the invention can reach 2,000,000 m/s
2Above micromechanics piezoresistance type acceleration sensor is to adopt the silicon micro-machining technology preparation, is general micromachined technology.
Its processing step is as follows:
1. silicon chip 1 back side pre-etching is 1 micron.
2. silicon chip 1 back side corrosion erodes away the activity space below the sensitive beam 2.
3. silicon chip 2 pre-etching are 2 microns, the air damping gap as with the lower cover bonding time.
4. silicon chip 2 corrosion form girder.
5. silicon chip 1,2 bondings.
6. the diffusion mask is done in oxidation.
7. photoetching resistance expands light boron, distributes again.
8. dense boron window is carved in photoetching.
9. expand dense boron, distribute again
10. lithography fair lead
11. evaporation of aluminum
12. anti-carve aluminium
13. the structure and the lower cover that anti-carve behind the aluminium carry out electrostatic bonding.
Thereby, finished range of the present invention and can reach 2,000,000 m/s
2The making of above micromechanics piezoresistance type acceleration sensor chip.
Description of drawings
Fig. 1 is the structure after micromechanics piezoresistance type acceleration sensor silicon chip 1 corrosion of the present invention.
Fig. 2 is the structure after micromechanics piezoresistance type acceleration sensor silicon chip 2 corrosion of the present invention.
Fig. 3 is the structure behind micromechanics piezoresistance type acceleration sensor silicon chip 1,2 bondings of the present invention.
Fig. 4 is the structure after micromechanics piezoresistance type acceleration sensor of the present invention and lower cover carry out the encapsulation of glass bonding.
Among the figure:
1. voltage dependent resistor (VDR) 2. sensitive beam 3. anchor districts 4. girders
5. the transition structure between mass 6. anchor districts and the sensitive beam
7. lower cover A. sensitive chip
Embodiment
Architectural feature of the present invention is described in detail by following preferred embodiment, but the present invention absolutely not only is confined to embodiment.
Embodiment 1
What make extra-high-speed measuring range acceleration sensor chip A employing of the present invention is micromachined technology.At first erode away sensitive beam 2 on the silicon substrate material silicon chip, the size of sensitive beam, length are 60 microns, 15 microns of thickness, 300 microns of width (Fig. 1); Then, erode away girder 4 on another sheet silicon chip, girder 4 is of a size of 400 microns of length, 100 microns of thickness, 2000 microns of width (Fig. 2).Two silicon chip high temperature bondings, oxidation diffuses to form sensitive resistance 1,10 microns of sensitive resistance bar width, 500 microns of length (Fig. 3).Sensor chip and lower cover 7 adopt the silex glass bonding, and 2 microns spacing is arranged between lower cover and the sensor chip, are used for controlling damping (Fig. 4).Under this size, this sensor natural frequency is 502kHz, and maximum stress is 220Mpa on the chip when bearing the 100000g acceleration, is lower than the breaking length of silicon.
Sensitive chip A, the sensitive beam size is with example 1, and girder length is 300 microns, and thickness, width are with example 1, and under this size, natural frequency is 750kHz, maximum stress is 210Mpa on the chip when bearing the 200000g acceleration, is lower than the breaking length of silicon.
Claims (4)
1. the range of a high natural frequency can reach 2,000,000 m/s
2Micro-machine acceleration transducer, it is characterized in that:
(1) this sensor is made up of transition structure and lower cover between voltage dependent resistor (VDR), sensitive beam, anchor district, girder, mass, anchor district and the sensitive beam;
(2) sensitive beam and girder are stacked position relation, and girder is positioned at the middle part of sensor construction;
(3) length of girder is more than 3 times of sensitive beam, is to realize by the transition structure between anchor district and the sensitive beam; The thickness of this transition structure is littler 1 micron than the thickness of substrate silicon chip, and length is the length difference of the length and the sensitive beam of girder;
(4) 4 sensitive beam are distributed in the two ends of mass symmetrically;
(5) sensitive resistance is designed to single straight line strip, 4 intersections that are placed in sensitive beam and anchor district;
(6) 2 microns gap is arranged between lower cover and the mass.
2. the range of high natural frequency according to claim 1 can reach 2,000,000 m/s
2Micro-machine acceleration transducer, it is characterized in that the width of described girder is identical with base widths, the width of sensitive beam is less than the width of middle girder.
3. the range of high natural frequency according to claim 1 can reach 2,000,000 m/s
2Micro-machine acceleration transducer, it is characterized in that described sensitive beam thickness is 10 μ m-50 μ m.
4. the range of high natural frequency according to claim 1 can reach 2,000,000 m/s
2Micro-machine acceleration transducer, it is characterized in that the described width that is designed to the sensitive resistance of single straight line strip is 10 μ m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02136742 CN1223859C (en) | 2002-08-30 | 2002-08-30 | Micro mechanical acceleration sensor of high natural frequency and measuring range up to 2 million m/s2 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02136742 CN1223859C (en) | 2002-08-30 | 2002-08-30 | Micro mechanical acceleration sensor of high natural frequency and measuring range up to 2 million m/s2 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1425922A CN1425922A (en) | 2003-06-25 |
| CN1223859C true CN1223859C (en) | 2005-10-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02136742 Expired - Fee Related CN1223859C (en) | 2002-08-30 | 2002-08-30 | Micro mechanical acceleration sensor of high natural frequency and measuring range up to 2 million m/s2 |
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| Country | Link |
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| CN (1) | CN1223859C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102967729A (en) * | 2012-09-18 | 2013-03-13 | 华东光电集成器件研究所 | Piezoresistive micro-electromechanical system (MEMS) accelerometer |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103323623B (en) * | 2013-07-02 | 2014-12-03 | 中国工程物理研究院电子工程研究所 | Three-convex-beam micromechanical accelerometer |
| CN104237559B (en) * | 2014-07-30 | 2017-01-18 | 昆山泰莱宏成传感技术有限公司 | Ultrahigh accelerating impact sensor based on embedded microcolumn and preparing method of ultrahigh accelerating impact sensor |
-
2002
- 2002-08-30 CN CN 02136742 patent/CN1223859C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102967729A (en) * | 2012-09-18 | 2013-03-13 | 华东光电集成器件研究所 | Piezoresistive micro-electromechanical system (MEMS) accelerometer |
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|---|---|
| CN1425922A (en) | 2003-06-25 |
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