A kind of capacitance pressure transducer and preparation method thereof
Technical field
The invention belongs to art of pressure sensors, it is related to a kind of capacitance pressure transducer and preparation method thereof, especially relates to
And a kind of capacitance pressure transducer of bulky capacitor change.
Background technology
Pressure transducer is the Parameters variation such as resistance, electric capacity, electric current, light to occur come test pressure by detection because of pressure
The sensor of change, pressure transducer, as acceleration transducer, is all the sensor having a large capacity and a wide range, and annual demand reaches
To tens.
Pressure transducer species is various, mainly has silicon piezoresistance type pressure sensor, resonance type pressure sensor, condenser type pressure
Force transducer etc., silicon piezoresistance type pressure sensor is to detect pressure by detecting silicon resistor resistance with change in pressure,
Because silicon resistor is semiconductor resistor, there is resistance and vary with temperature in this pressure transducer, also adopt pn-junction to isolate,
Have such problems as that pn-junction is leaked electricity, its process circuit should complete detection signal pickup and the processing and amplifying of resistance signal, enters again
The temperature-compensating of row silicon resistor, this just proposes very high requirement to process circuit, and therefore, silicon piezoresistance type pressure sensor limits
In cost, it is mainly used in the field that required precision is not high, environmental requirement is not high.Resonance type pressure sensor is using sensor
The pressure-dependent feature of natural resonance frequency detecting pressure, it eliminate sensor because external environment change (such as: temperature,
Magnetic etc.) cause impact that pressure detecting precision is brought, it is the first-selected sensor of high-precision pressure detection, but difficulty of processing
Larger, also only have three companies to succeed in developing in the world at present.Capacitance pressure transducer is the relative position meeting of capacitor plate
Changing with the change of pressure, thus causing the change of electric capacity, by the measurement to electric capacity for the testing circuit, realizing the survey of pressure
Amount.This sensor eliminates the electric leakage of silicon piezoresistance type pressure sensor pn-junction, resistance varies with temperature asking of brought impact
Topic, also has the advantages that low-power consumption simultaneously, is the desired pressure sensor of medium accuracy pressure detecting, but due to electric capacity processing
Difference in methods, performance difference is also very big.Patent documentation 1 " capacitor type semiconductor pressure sensor " (application number:
03147270.2) propose to make movable capacitor plate using polysilicon, the metal fixed electrode polycrystalline silicon diaphragm institute movable with
The capacity plate antenna (plate capacitor) constituting, is arranged in a non-monocrystalline silicon substrate, becomes a kind of condenser type quasiconductor pressure
Force transducer, the pressure transducer that this method makes to be differed from very compared with rustless steel or monocrystal silicon due to polysilicon Young's moduluss
Many, cause that polycrystalline silicon diaphragm fatigue resistance is poor, therefore reliability is not high, in addition, the cavity between this electric capacity is apart from little, electricity
Hold excursion little, very high requirement is proposed to peripheral electric circuit inspection;The polycrystalline silicon diaphragm of sensing ambient pressure and lead are
Coplanar, needs to increase protection technique to protect lead, it is to avoid by ectocine.Patent documentation 2 " the big relative variation electricity of high q value
Hold pressure transducer " (application number: 201010548819.3), propose to form capacitor by the elastic vibration diaphragm of periphery fixed,
By adjusting the means such as ratio, the setting insulation salient point of circular electrode and vibrating diaphragm radius, vibrating diaphragm is made to be in big strain shape
State, maximum capacitor is as big as possible with the ratio of initial capacitance, so that electric capacity reaches big relative variation, the purpose of high q value.The party
Although method is capable of bulky capacitor change, reduce the requirement of peripheral testing circuit, vibrating diaphragm can using high Young's modulus not
Rust Steel material makes, and improves fatigue resistance, improves reliability further, but the volume of whole electric capacity is larger, batch production
Ability
Content of the invention
In view of this, it is an object of the invention to provide a kind of capacitance pressure transducer and preparation method thereof.
For reaching above-mentioned purpose, the present invention following technical scheme of offer:
A kind of capacitance pressure transducer is flat including be made up of conductive single crystal silicon movable electrode plate and metal fixed electrode
Plate electric capacity it is characterised in that: also include conductive single crystal silicon base and be arranged on conductive single crystal silicon movable electrode plate and conductive single crystal
Conductance supporting structure between silicon base, described conductive single crystal silicon movable electrode plate, conductive single crystal silicon base and conductance supporting knot
Structure intermediate formation airtight chamber, described metal fixed electrode is arranged in the conductive single crystal silicon base within airtight chamber;Described
Conductive single crystal silicon base includes multiple conductive single crystal silico briquettes insulated from each other, in the plurality of conductive single crystal silico briquette each piece all different
When connect with conductive single crystal silicon movable electrode plate and metal fixed electrode, but at least respectively have one piece movable with conductive single crystal silicon respectively
Battery lead plate connects with metal fixed electrode.
Preferably, described conductive single crystal silicon movable electrode plate includes monocrystalline silicon electrode barrier film and monocrystal silicon support column, this electricity
Pole barrier film bottom is provided with elastica chamber, and top is provided with movable plate chamber.
Preferably, described conductive single crystal silicon movable electrode sheet material matter is n+ type monocrystal silicon, and described monocrystalline silicon electrode barrier film is thick
Spend for 105-155 μm, the depth of elastica chamber is 250 ± 10 μm, the depth of movable plate chamber is 20 ± 5 μm.
Preferably, described conductive single crystal silicon base includes two pieces of left and right insulated from each other, the two pieces of monocrystalline silicon substrates in described left and right
Bottom top is respectively equipped with conductive terminals, and bottom is respectively equipped with projection, the Gui Cao area between the two pieces of monocrystal silicon substrate in described left and right
And isolation area in addition to projection for the lower surface is equipped with insulant, described conductance supporting structure and metal fixed electrode respectively with a left side
Side or the raised directly contact on right side.
Preferably, described conductive single crystal silicon substrate bottom materials are n+ type monocrystal silicon, and thickness is 400 ± 10 μm, and resistivity is
0.008-0.01ω.cm;Described metal fixed electrode material be silicon content 0.7-1.2% silico-aluminum, thickness be 1.2 ±
0.1μm.
Preferably, described insulant is glass dust.
Preferably, conductance supporting structure is titanium-tungsten and alusil alloy two layer composite structure.
Preferably, the lower surface of described metal fixed electrode is provided with silicon dioxide layer.
The method that the present invention prepares described capacitance pressure transducer, prepare first conductive single crystal silicon movable electrode plate,
Then prepare fixed electrode, finally group to gained monocrystal silicon movable electrode plate and fixed electrode and remove fixed electrode excess portion
Get product.
Further, described conductive single crystal silicon movable electrode plate is obtained by following steps:
1), choose n+ type monocrystalline silicon piece and carry out twin polishing;
2), oxidation step 1) monocrystalline silicon piece so as to Surface Creation silicon dioxide layer;
3), in step 2) monocrystalline silicon piece double-sided deposition silicon nitride layer;
4), etching removes the silicon nitride at elastica chamber and silicon dioxide;
5), etching removes the silicon nitride at movable plate chamber;
6), etch the silicon at elastica chamber for the first time using etching solution;
7), etching removes the silicon dioxide at movable plate chamber;
8), with the silicon at step etching movable plate chamber and elastica chamber to designated depth;
9), remaining silicon nitride and silicon dioxide are removed.
Further, comprise the following steps when preparing described fixed electrode:
1), choose n+
Type monocrystalline silicon piece, single-sided polishing, two-sided oxidation make its Surface Creation silicon dioxide layer;
2), etch removal step 1) silicon dioxide at monocrystalline silicon piece burnishing surface Gui Cao area and isolation area;
3), first etching removes the silicon in Gui Cao area;
4), synchronous etching removes the silicon at Gui Cao area and isolation area;
5), remove remaining silicon dioxide layer;
6), glass dust is coated uniformly on Gui Cao area and isolation zone position hot setting;
7), in step 6) monocrystal silicon Gui Cao area surface sputtered aluminum silicon fixed electrode, isolation area surface sputtered aluminum silicon close
Layer gold, described aluminum silicon fixed electrode and alusil alloy layer projection contacts different from monocrystalline silicon piece bottom respectively and between the two not
Conducting;
8), in step 7) alusil alloy layer surface one layer of titanium-tungsten of sputtering.
Further, pressure transducer group is to carrying out as follows:
1), by conductive single crystal silicon movable electrode plate and fixed electrode be aligned overlapping, and accelerate the gold in conductance supporting structure
Belong to diffusion, make both reliable bond;
2), by step 1) the fixed electrode silicon chip that has been bonded carries out thinning, polishing, exposes the insulant in isolation channel;
3), in step 2) the fixed electrode back side, isolation channel both sides sputter respectively or evaporate drawing of two capacitor plates of setting
Line electrode.
The beneficial effects of the present invention is:
As electric capacity movable plate after low resistance monocrystalline silicon piece tow sides corrode and deep trouth, contact is extraneous to press the present invention
The elastica chamber of power can be used to adjust the thickness of monocrystalline silicon thin film, and movable plate chamber can be used to control between capacitor plate
Electric capacity;The depth of the electric capacity movable plate chamber of this structure is up to 10-30 μm, far above conventional capacitance polar plate spacing, permissible
Capacitance variations value is significantly increased, and then improves the sensitivity of sensor and reduce the complexity of circuit;In addition, this structure also has
There are Young's moduluss high, non-damageable advantage.The fixed electrode of the present invention is made up of polylith monocrystal silicon substrate insulated from each other, gold
Belong to the exit that electrode is immediately directed against electric capacity by the projection of low-resistance silicon, movable low-resistance silicon movable plate electrode passes through conductance supporting structure
It is connected with another projection of low-resistance silicon, then guide to another exit of electric capacity again by low-resistance silicon, and the exit of electric capacity
Setting overleaf, is effectively simplified circuit, it is to avoid the metal of electric capacity exit is subject to external influence.
Brief description
In order that the purpose of the present invention, technical scheme and beneficial effect are clearer, the present invention provides drawings described below to carry out
Illustrate:
Fig. 1 is the cross sectional shape figure of embodiment 1 capacitance pressure transducer;
Fig. 2 is the n+ type monocrystalline silicon piece a cross sectional shape figure of embodiment 1;
Fig. 3 is the n+ type monocrystalline silicon piece a oxidation of Fig. 2, the cross sectional shape figure after deposited silicon nitride;
Fig. 4 is Fig. 3 first photoetching elasticity diaphragm area silicon, removes the cross sectional shape figure after the silicon nitride of movable plate region;
Fig. 5 is the cross sectional shape figure after Fig. 4 synchronously etches elastic diaphragm area and movable plate region silicon;
Fig. 6 removes the cross sectional shape figure after silicon nitride, silicon dioxide for Fig. 5;
Fig. 7 is the n+ type monocrystalline silicon piece a cross sectional shape figure of embodiment 1;
Fig. 8 is the cross sectional shape figure after the n+ type monocrystalline silicon piece a oxidation processes of Fig. 7;
Fig. 9 removes after monocrystal silicon at the silicon dioxide layer of Gui Cao area c and isolation area d first bite Gui Cao area c for Fig. 8
Cross sectional shape figure;
Figure 10 be synchronous corrosion Tu9Zhong Guicao area c and isolation area d monocrystal silicon after and after removing remaining silicon dioxide layer
Cross sectional shape figure;
Figure 11 is the cross sectional shape figure after Figure 10 Zhong Guicao area c and isolation area d coating glass slurry, solidification polishing;
Figure 12 sputters the cross sectional shape figure after sial photoetching for Figure 11;
Figure 13 deposits the cross sectional shape figure after silicon dioxide layer and titanium tungsten gold photoetching for Figure 12;
Figure 14 is that embodiment 1 Figure 13 is aligned the cross sectional shape figure after overlapping with Fig. 6.
Specific embodiment
Below in conjunction with accompanying drawing, the preferred embodiments of the present invention are described in detail.
Embodiment 1:
As shown in figure 1, the capacitance pressure transducer of the present embodiment, including by conductive single crystal silicon movable electrode plate 1 and gold
Belong to the capacity plate antenna that fixed electrode 2 is constituted, also include conductive single crystal silicon base 3 and be arranged on conductive single crystal silicon movable electrode plate 1
Conductance supporting structure 4 and conductive single crystal silicon base 3 between, described conductive single crystal silicon movable electrode plate 1, conductive single crystal silicon base
3 and conductance supporting structure 4 intermediate formation airtight chamber, described metal fixed electrode 2 is arranged on conductive single within airtight chamber
In crystal silicon substrate 3;Described conductive single crystal silicon base 3 includes multiple conductive single crystal silico briquettes insulated from each other, the plurality of conductive single
In crystal silicon block, each piece is connected with conductive single crystal silicon movable electrode plate 1 and metal fixed electrode 2 when all different, but at least respectively has one piece
Connect with conductive single crystal silicon movable electrode plate 1 and metal fixed electrode 2 respectively.
In the present embodiment, described conductive single crystal silicon movable electrode plate 1 includes monocrystalline silicon electrode barrier film 1-1 and monocrystal silicon supporting
Post 1-2, this electrode diaphragm bottom is provided with elastica chamber 1-4, and top is provided with movable plate chamber 1-3.
In the present embodiment, described conductive single crystal silicon movable electrode plate 1 material is n+ type monocrystal silicon (low-resistance silicon), described monocrystalline
Silicon electrode barrier film 1-1 thickness is 105-155 μm, and the depth of elastica chamber 1-4 is 250 ± 10 μm, movable plate chamber 1-3's
Depth is 20 ± 5 μm.
In the present embodiment, described conductive single crystal silicon base 3 includes two pieces of left and right insulated from each other 3-1,3-2, described left and right
Two pieces of monocrystal silicon substrate 3-1,3-2 tops are respectively equipped with conductive terminals 3-5, and bottom is respectively equipped with raised 3-4, described left and right two
Isolation area 3-6 in addition to raised 3-4 for the Gui Cao area 3-3 and lower surface between block monocrystal silicon substrate 3-1,3-2 is equipped with insulation material
Material, described conductance supporting structure 4 and the metal fixed electrode 2 raised 3-4 directly contact with left side or right side respectively.
In the present embodiment, described conductive single crystal silicon base 3 material is n+ type monocrystal silicon, and thickness is 400 ± 10 μm, resistivity
For 0.008-0.01 ω .cm;Described metal fixed electrode 2 material is the silico-aluminum of silicon content 0.7-1.2%, and thickness is 1.2
±0.1μm.
In the present embodiment, described insulant is glass dust.
In the present embodiment, conductance supporting structure 4 is titanium-tungsten 4-1 and alusil alloy 4-2 two layer composite structure.
In the present embodiment, the lower surface of described metal fixed electrode 2 is provided with silicon dioxide layer 2-1.
The method that the present embodiment prepares capacitance pressure transducer, comprises the following steps:
First, prepare conductive single crystal silicon movable electrode plate:
1), choose n+ type monocrystalline silicon piece a as shown in Figure 2 and carry out twin polishing (100 crystal orientation, 400 ± 10 μm of thickness, electricity
Resistance rate 0.008-0.01 ω .cm);
2), clean, oxidation step 1) monocrystalline silicon piece a so as to Surface Creation thickness is 1 ± 0.1 μm of silicon dioxide layer
b;
3), in step 2) monocrystalline silicon piece two-sided lpcvd deposited silicon nitride layer c, thickness be 130 ± 10nm, as Fig. 3 institute
Show;
4), photoetching senses the elastic diaphragm area d of ambient pressure, etches away the nitrogen on this region by dry and wet method
SiClx c and silicon dioxide b, remove photoresist;
5), dual surface lithography movable plate region e, is fallen the silicon nitride c on this region, leaves silicon dioxide by dry etching
B, removes photoresist;
6), adopt koh+h2O or the silicon of ethylenediamine, aqueous solution (epw) the corrosion area d of catechol, etching depth is
230 ± 10 μm, at this moment because movable plate region e has silicon dioxide to protect, silicon below is not corroded, as shown in Figure 4;
7) method, adopting wet etching silicon dioxide, erodes the silicon dioxide b of movable plate region e, other has nitrogen
The region of SiClx c protection silicon dioxide b below is not corroded;
8), adopt koh+h2O or ethylenediamine, the aqueous solution (epw) of catechol are with step etching movable plate region e and bullet
Property diaphragm area at d silicon, the depth of control corrosion rate is 20 ± 5 μm, and at this moment the silicon depth of elastic diaphragm area d is 250 ± 10 μm, such as
Shown in Fig. 5;
9), remove remaining silicon nitride c and silicon dioxide b on silicon chip, complete the preparation of conductive single crystal silicon movable electrode plate,
As shown in Figure 6.
2nd, prepare fixed electrode:
1), n+ type monocrystalline silicon piece a (100 crystal orientation, single-sided polishing piece, 400 ± 10 μm of thickness, resistivity 0.008- are chosen
0.01 ω .cm), as shown in Figure 7;
2), clean, oxidation, obtain, in monocrystalline silicon surface, silicon dioxide layer b that thickness is 1 ± 0.1 μm, as shown in Figure 8;
3), monocrystalline silicon piece burnishing surface Gui Cao area c and isolation area d, then wet etching are made by lithography initially with photoetching method
Remove silicon dioxide layer b at Gui Cao area c and isolation area d, remove photoresist;
4), carve the Gui Cao area c of isolation silicon electrode initially with photoetching method set, solidify photoresist, then adopt dry method
The silicon of corrosion Gui Cao area c, etch depth is 150 ± 20 μm, removes photoresist, and now isolation area d, should due to there being photoresist to protect
The silicon in region is not corroded, as shown in Figure 9;
5), adopt dry method synchronously to etch the silicon removing at Gui Cao area c and isolation area d, control etch depth to be 80 ± 10 μm,
Now the depth of isolation silicon electrode Gui Cao area c is 230 ± 20 μm;
6), remove remaining silicon dioxide layer, as shown in Figure 10;
7), adopt spin coating method, the glass dust e of liquid is uniformly coated on region c, d, then in 400 degree of conjunction
Solidify in golden stove;
8), adopt cmp finishing method, the glass dust e planarizing on region c, d allows and do not need filling glass powder region
Silicon exposed out, as shown in figure 11;
9), initially with sputtering method, sputter one layer of sial f in n+ type monocrystalline silicon piece a lower surface, sial silicon content is
1%, thickness is 1.2 ± 0.1 μm, by photoetching method, makes sial metal polar plate and the becket for metal bonding by lithography, such as
Shown in Figure 12;
10), the silicon dioxide that a layer thickness is 120 ± 20nm is precipitated on sial metal polar plate surface using pecvd technique
g;
11), fuming nitric aicd is utilized to clean, then sputtering a layer thickness in the metal ring surface for metal bonding is 200
± 20nm titanium tungsten gold h, in this titanium tungsten gold h, titanium tungsten mass ratio is 1:1, as shown in figure 13.
3rd, pressure transducer group pair:
1), use fuming nitric aicd cleaning step two gained fixed electrode first, cleaning step one gained conductive single crystal silicon is movable
Battery lead plate, then uses and corrodes 4 minutes under the hf diluent room temperature of 50:1, remove natural oxidizing layer on silicon chip 1, finally utilizes two-sided
Aforementioned fixed electrode and conductive single crystal silicon movable electrode plate, be aligned are stacked together by litho machine;
2) under vacuum pressed, enter row metal diffusion interlinked, such fixed electrode and conductive single crystal silicon movable electrode plate are firm
Admittedly be bonded together, due to the silicon chip of movable electrode plate have one control capacitance variations scope deep trouth, such silicon Thin Elastic
The silicon chip of film is exactly electric capacity movable electrode plate, and the metallic plate on glass dust is exactly the fixed polar plate of electric capacity, bottom crown in formation
Variable capacitance, as shown in figure 14;
3), by step 1) the fixed electrode silicon chip that has been bonded carries out thinning, polishing, exposes the glass dust e in isolation channel c;
4), one layer of sial 15, photoetching are deposited on the face of glass dust isolation channel having exposed silicon chip using sputtering method
Go out the lead electrode of two plates capacitances, obtain as shown in Figure 1;
5), alloy (440 degree, nitrogen hydrido is golden, half an hour), allow lead electrode metal and n+ silicon form good ohm and connect
Touch, obtain the capacitance pressure transducer of the present invention, its structure is as shown in Figure 1.
It is it should be noted that process used in the inventive method, in addition to being described in detail, other,
As cleaning, oxidation;Deposit silicon nitride, silicon dioxide;Splash-proofing sputtering metal;Dry etching silicon nitride, silicon;Wet etching silicon dioxide,
Silicon;Photoetching;Remove photoresist;Alloy, the technique such as thinning, polishing, is all this integrated circuit and the common process technology in mems field, no longer
Auspicious state.
Need explanation, claims forms part and specific embodiment that partly same part is employed with different accompanying drawing marks
Note, it will be appreciated by those skilled in the art that above-mentioned different reference is used for the purpose of facilitating language to describe, can't lead to
Ambiguity.
Finally illustrate, preferred embodiment above only in order to technical scheme to be described and unrestricted, although logical
Cross above preferred embodiment the present invention to be described in detail, it is to be understood by those skilled in the art that can be
In form and various changes are made to it, without departing from claims of the present invention limited range in details.