A kind of silicon piezoresistance type accelerometer detected based on josephson effect
Technical field
The present invention relates to micro-inertial navigation technology association area, in particular to a kind of silicon piezoresistance type micro-mechanical accelerometer detected based on josephson effect.
Background technology
Along with the development of micro mechanical system (MEMS) technology, it possesses, and cost is low, volume is little, easy mass production and the feature such as integration is good, more and more receives the concern of people, is widely used in civilian and military field.But due to the restriction of Key Performance Indicator, micro mechanical sensor is not also applied fully in leading-edge fields such as military affairs, space flight, aviations.Wherein, sensitivity and range are the key indexs that micro mechanical sensor has much room for improvement, and utilize the sensor that main flow principle manufactures, and the raising of its sensitivity all depends on the reduction of the rigidity of structure, and high sensitivity is along with small-range, low overload.
The ultimate principle of silicon piezoresistive effect acceleration transducer is that the mass of semi-girder free end is subject to Moment by semi-girder during acceleration effect and produces stress, resistance is changed, improve the rigidity that range certainly will will improve beam, its resolution can be reduced accordingly.The resistance variations produced when the low input of high overload sensor is very little, and corresponding bridge road exports and is about 50-200nV/g, substantially flood by circuit noise.That is, silicon piezoresistive effect acceleration transducer high overload and highly sensitively there is contradiction: high overload be realized and just must abandon must detecting low g value.
We once proposed josephson effect to be applied to piezoresistive effect and detected the high precision test (application for a patent for invention number: CN201210058424.4) that can realize faint stress, the faint DC energy signal exported by pressure drag electric bridge by Josephson device is transformed into AC energy signal, by can realize the accurate detection to direct current signal to the frequency detecting of AC energy signal, its resolution comparatively traditional approach detection can improve 2-3 the order of magnitude.For the application demand of accelerometer, it is simple that we expect that accelerometer has technique, and signal to noise ratio (S/N ratio) is high, characteristic easy to detect.Research finds by superconductor niobium, i.e. Nb, and the S-I-S type Josephson junction as superconducting layer composition has better ease for use and technological feasibility, and can prepare by magnetron sputtering vapo(u)rization system, average molecular beam epitaxy technology has more low-cost advantage." one " font Josephson junction structure relatively " ten " font junction structure requires low to microwave, technique is more easy, be more suitable for the sensitive structure as mems accelerometer, simultaneously, the digital step count detection of the current step effect of Josephson junction is lower relative to the a-c cycle detection testing cost of relative AC Josephson effect, more holds and realizes high precision test.
Summary of the invention
The present invention is intended at least to solve one of technical matters existed in prior art.
In view of this, the present invention needs to provide micro-mechanical accelerometer, this micro-mechanical accelerometer is the silicon piezoresistance type micro-mechanical accelerometer detected based on josephson effect, at least can improve the accuracy of detection of micro-mechanical accelerometer, the accuracy of detection especially under high overload.The invention provides a kind of silicon piezoresistance type micro-mechanical accelerometer detected based on josephson effect, comprising: bonding substrate, support frame, support frame is located at bonding surface and is connected with bonding substrate; Elastic beam, elastic beam is for supporting the mass of accelerometer, and two ends connect support frame and mass respectively, and elastic beam upper surface is parallel with mass top surface with support frame, and its thickness is less than mass thickness; Mass, mass is fixed in the middle of support frame by elastic beam, and thickness is less than support frame thickness; Organize voltage dependent resistor (VDR), often organize voltage dependent resistor (VDR) and comprise four voltage dependent resistor (VDR)s, wherein two voltage dependent resistor (VDR)s are located at elastic beam root, and another two voltage dependent resistor (VDR)s are located on support frame, and are positioned at the adjacent domain that support frame is connected with elastic beam more;
Organize Josephson device more, often organize Josephson device and be positioned at support frame upper surface, and be close to two voltage dependent resistor (VDR)s that support frame upper surface is arranged, corresponding with each elastic beam position.
According to the silicon piezoresistance type micro-mechanical accelerometer detected based on josephson effect of the embodiment of the present invention, by Josephson device and silicon pressure drag integrated, utilize the change in voltage that the volt-ampere catastrophe characteristics of josephson effect causes to measure silicon pressure drag, input acceleration is converted into the step change of electric current, the digital accurate detection of acceleration can be realized by current step counting, rational in infrastructure, highly sensitive, Digital output, testing circuit is simple, easy to use, good reliability, be applicable to microminiaturized.Effectively can solve the difficult problem such as muting sensitivity, low effective resolution, high detection bottom threshold that high overload type sensor exists.
According to one embodiment of present invention, described Josephson device is inputted negative pole formed by silicon substrate, silicon dioxide, superconducting metal layer, Josephson junction, superconducting metal layer, voltage input positive pole, voltage; Be manufactured with silicon dioxide layer on a silicon substrate, silicon dioxide layer is deposited with superconducting metal layer, superconducting metal layer is manufactured with Josephson junction, Josephson is tied and is deposited with superconducting metal layer, superconducting metal layer is connected with voltage input positive pole, and superconducting metal layer is connected with voltage input negative pole.
The structural material of described Josephson device is made up of layer-of-substrate silicon, silicon dioxide layer, niobium layer, oxidation lead layer, niobium layer; Layer-of-substrate silicon is manufactured with silicon dioxide layer, i.e. SiO
2layer, silicon dioxide layer is manufactured with niobium layer, i.e. Nb layer, niobium layer is manufactured with alumina layer, i.e. Al
2o
3layer, alumina layer is manufactured with niobium layer, i.e. Nb layer.
According to one embodiment of present invention, described Josephson device adopts " one " font S-I-S structure, i.e. superconducting metal-insulation course-superconducting metal.Easier relative to " ten " font S-I-N-S structural manufacturing process, be more suitable for being applied to micro-mechanical accelerometer.
According to one embodiment of present invention, described mass is " ten " font, and mass minor face is 1/6 of long limit, effectively can reduce the impact of micro-mechanical accelerometer high order mode.
According to one embodiment of present invention, four described voltage dependent resistor (VDR) doping contents are identical, and physical dimension is identical, but arranged direction is different, two adjacent arranged direction differ 90 °, i.e. resistance size opposite number each other, two relative arranged direction are consistent, and namely resistance size is identical.
According to one embodiment of present invention, four described voltage dependent resistor (VDR)s connect into wheatstone bridge circuits, and Qi Qiao road output terminal is connected to voltage input positive pole, the voltage input negative pole of Josephson device, and wherein electric current flows through current step pick-up unit.Described current step pick-up unit is the device for sense acceleration meter output signal, by judging that rise-time of current angle realizes step counting, without the need to obtaining precision current value, can realize digital detection.
According to one embodiment of present invention, described voltage dependent resistor (VDR) and Josephson device have four groups respectively, and position is relative with four elastic beams respectively.Wherein one group or all is selected, to improve yield rate or the reliability of accelerometer during application.
Additional aspect of the present invention and advantage will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present invention.
Accompanying drawing explanation
Above-mentioned and/or additional aspect of the present invention and advantage will become obvious and easy understand from accompanying drawing below combining to the description of embodiment, wherein:
Fig. 1 is the one-piece construction figure of the embodiment of the present invention;
Fig. 2 is the integrally-built vertical view of the embodiment of the present invention;
Fig. 3 is the A-A sectional view of Fig. 2 of the embodiment of the present invention
Fig. 4 is the mass vertical view of the embodiment of the present invention;
Fig. 5 is the Josephson device three-dimensional structure diagram of the embodiment of the present invention;
Fig. 6 is the Josephson device side view of the embodiment of the present invention;
Fig. 7 is the Josephson device structural drawing of the embodiment of the present invention;
Fig. 8 is the Josephson device Cleaning Principle figure of the embodiment of the present invention;
Fig. 9 is the Cleaning Principle schematic diagram of the embodiment of the present invention;
Shown in figure, list of numerals is as follows:
1, bonding substrate, 2, support frame, 3, mass, 4, elastic beam, 5, Josephson device, 6-9, voltage dependent resistor (VDR), 10, silicon substrate, 11, silicon dioxide, 12, superconducting metal layer, 13, Josephson junction, 14, superconducting metal layer, 15, voltage input positive pole, 16, voltage input negative pole, 17, layer-of-substrate silicon, 18, silicon dioxide layer, 19, niobium layer, 20, oxidation lead layer, 21, niobium layer, 22-23, mass minor face, 24, quality block length limit.
Embodiment
Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Being exemplary below by the embodiment be described with reference to the drawings, only for explaining the present invention, and can not limitation of the present invention being interpreted as.
In describing the invention, it will be appreciated that, orientation or the position relationship of the instruction such as term " " center ", " on ", D score, "front", "rear", "left", "right" be based on orientation shown in the drawings or position relationship; be only the present invention for convenience of description and simplified characterization; instead of instruction or imply the device of indication or element must have specific orientation, with specific azimuth configuration and operation, therefore can not be interpreted as limitation of the present invention.
In describing the invention, it should be noted that, unless otherwise clearly defined and limited, term " is connected ", " connection " should be interpreted broadly, such as, can be fixedly connected with, also can be removably connect, or connect integratedly; Can be mechanical connection, also can be electrical connection; Can be directly be connected, also indirectly can be connected by intermediary, can be the connection of two element internals.For the ordinary skill in the art, concrete condition above-mentioned term concrete meaning in the present invention can be understood.
Josephson effect is Cooper electronic pair by the quantum mechanical tunneling occurred during thin dielectric layer between two pieces of superconducting metals.When DC current is by superconducting tunnel junction, as long as current value is lower than a certain critical current I
c, then similar to one piece of superconductor, there is not any voltage in tunnel junctions, and what namely flow through tunnel junction is supercurrent.If exceed critical electric current value I
c, namely there is a limited voltage in tunnel junctions, the proterties of tunnel junction is transitioned into the tunneling characteristics of normal electrical.With additional microwave signal excitation Josephson junction, make ω
f=n ω
rtime, will comprise some DC component in Josephson current, at this moment on the I-V family curve of Josephson junction, have a series of constant-voltage power supply step to occur, step is spaced apart
, josephson frequency-voltage transitions is closed and is
In formula: ω
r---be the angular frequency of microwave excitation signal; H=/2 π (for Planck constant).This formula is josephson frequency-voltage transitions relational expression.This relational expression is blanket, when exciting signal frequency must be, and the step-length strict conformance of current step in its I-V relation.Therefore, as long as obtain step number n just accurately can obtain magnitude of voltage.Josephson effect and silicon piezoresistance type acceleration detection mode are combined, and is applied to the context of detection of micro-mechanical accelerometer, the digital detection of acceleration can be realized, reduce input difficulty, improve the accuracy of detection of micro-mechanical accelerometer.
Below in conjunction with accompanying drawing, the present invention will be further described:
As shown in Figure 1-2, according to an embodiment of the invention based on josephson effect micro-mechanical accelerometer, comprising: bonding substrate 1; Support frame 2, support frame 2 to be located at above bonding substrate 1 and to be connected with bonding substrate 1; Josephson device 5, Josephson device 5 is positioned at support frame 2 upper surface, and the voltage dependent resistor (VDR) 6,9 of arranging with support frame 2 upper surface is contiguous, and corresponding with each elastic beam 4 position; Elastic beam 4 is for supporting the mass 3 of accelerometer, and two ends connect support frame 2 and mass 3 respectively, and elastic beam 4 upper surface and support frame 2 are with mass 3 upper surface to parallel, and the thickness of elastic beam 4 is less than the thickness of mass 3; Mass 3 is fixed in the middle of support frame by elastic beam, and mass 3 thickness is less than support frame 2 thickness; With voltage dependent resistor (VDR) 6,7,8,9, wherein voltage dependent resistor (VDR) 8,9 are located at elastic beam 4 root, voltage dependent resistor (VDR) 6, and 7 are located on support frame (2), and are positioned at the adjacent domain that support frame (2) is connected with elastic beam (4).
It should be noted that described voltage dependent resistor (VDR) 6,7,8,9 doping contents are identical, and physical dimension is identical, but arranged direction is different, and two adjacent arranged direction differ 90 °, i.e. resistance size opposite number each other, two relative arranged direction are consistent, and namely resistance size is identical.Wherein, voltage dependent resistor (VDR) 8,9 root areas being in elastic beam 4, namely elastic beam 4 produces the most obvious region of strain, and voltage dependent resistor (VDR) 6,7, Josephson device 5 are made on support frame 2, require that voltage dependent resistor (VDR) 6,7, Josephson device 5 can not by the impacts of extraneous strain.
Voltage dependent resistor (VDR) 6,7,8,9 and Josephson device 5 have four groups respectively, position is relative with four elastic beams 4 respectively.Wherein one group or all is selected, to improve yield rate or the reliability of accelerometer during application.
As shown in Figure 3, according to one embodiment of present invention, the thickness of elastic beam 4 is less than mass 3 thickness, and the thickness of mass 3 is less than the thickness of support frame 2, to ensure that elastic beam is for the most responsive structure of inertial force, can move up and down along Z axis under the effect of inertial force simultaneously.
Specifically, when based on josephson effect micro-mechanical accelerometer when there being faint acceleration to input, the size of elastic beam 4 perception inertial force corresponding generation deformation, the voltage dependent resistor (VDR) 6,7,8 that elastic beam 4 root makes, mechanical signal is transformed into electrical signal by 9.
As shown in Figure 4, according to one embodiment of present invention, mass 2 is " ten " font, and mass minor face 22,23 is 1/6 of long limit 24, to reduce the impact of micro-mechanical accelerometer high order mode.
As seen in figs. 5-6, according to one embodiment of present invention, Josephson device 5 adopts " one " font S-I-S structure, i.e. superconducting metal-insulation course-superconducting metal, Josephson device 5 is inputted negative pole 16 formed by silicon substrate 10, silica 11, superconducting metal layer 12, Josephson junction 13, superconducting metal layer 14, voltage input positive pole 15, voltage; Silicon substrate 10 is manufactured with silicon dioxide layer 11, silicon dioxide layer 11 is deposited with superconducting metal layer 12, superconducting metal layer 12 is manufactured with Josephson junction 13, Josephson junction 13 is deposited with superconducting metal layer 14, superconducting metal layer 12 is connected with voltage input positive pole 15, and superconducting metal layer 14 is connected to voltage input negative pole 16.
As shown in Figure 7, according to one embodiment of present invention, the structural material of Josephson device 5 is made up of layer-of-substrate silicon 17, silicon dioxide layer 18, niobium layer 19, oxidation lead layer 20, niobium layer 21; Layer-of-substrate silicon 17 is manufactured with silicon dioxide layer 18, i.e. SiO
2layer, silicon dioxide layer 18 is manufactured with niobium layer 19, i.e. Nb layer, niobium layer 19 is manufactured with alumina layer 20, i.e. Al
2o
3layer, alumina layer 20 is manufactured with niobium layer 21, i.e. Nb layer.It should be noted that, the mode of thermal oxide can be adopted to realize reducing technology difficulty at silicon dioxide layer 18 and alumina layer 20, also effectively can prevent the discontinuous Weak link caused of barrier layer, the thickness of oxide layer is not about 10-100 not etc.Niobium layer 19 and niobium layer 21 can be prepared by magnetron sputtering vapo(u)rization system, average molecular beam epitaxy technology has more low-cost advantage, sedimentary environment is high vacuum, evaporation direction vertically downward, in deposition process, need the strict quality, the thickness that control film forming, with the accuracy of detection of the quality and thickness effect micro-mechanical accelerometer of avoiding film forming and sensitivity.
As shown in Figure 8 according to one embodiment of present invention, change in voltage can be converted to the curent change of step-length strict conformance by described Josephson device 5 under certain frequency microwave irradiation, and its step-length is only relevant with irradiation frequency.
As shown in Figure 9, according to one embodiment of present invention, its Cleaning Principle is the voltage dependent resistor (VDR) 6 on elastic beam 4,7,8,9 composition Wheatstone bridges, degree of will speed up signal is converted to change in voltage, voltage signal is loaded into voltage input positive pole 15 and the voltage input negative pole 16 of Josephson device 5, by Josephson device 5, voltage signal is converted to the current signal of step change, can be obtained the size of input acceleration by the counting of current step.
In the description of this instructions, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " illustrative examples ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, identical embodiment or example are not necessarily referred to the schematic representation of above-mentioned term.And the specific features of description, structure, material or feature can combine in an appropriate manner in any one or more embodiment or example.
Although illustrate and describe embodiments of the invention, those having ordinary skill in the art will appreciate that, can carry out multiple change, amendment, replacement and modification to these embodiments when not departing from principle of the present invention and aim, scope of the present invention is by claim and equivalents thereof.