CN104198762A - Eight-beam symmetrical silicon micro-accelerometer - Google Patents
Eight-beam symmetrical silicon micro-accelerometer Download PDFInfo
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- CN104198762A CN104198762A CN201410447900.0A CN201410447900A CN104198762A CN 104198762 A CN104198762 A CN 104198762A CN 201410447900 A CN201410447900 A CN 201410447900A CN 104198762 A CN104198762 A CN 104198762A
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Abstract
The invention provides an eight-beam symmetrical silicon micro-accelerometer. The capacitive micro-accelerometer comprises three portions of an upper silicon electrode plate, a sensitive chip and a lower silicon electrode plate from top to bottom, wherein the sensitive chip is of a micro-structure of 'mass block-cantilever beams'; eight cantilever beams are provided, and symmetrically distributed around a mass block, and the mass block is located at a middle horizontal position; the thickness of the mass block is the same as that of the adopted silicon slice, and the shape is a polygon so as to effectively utilize the space, thus the quality is greatly improved, and a lower device noise and a higher sensitivity can be obtained; the micro-accelerometer adopts an all-silicon process, the silicon electrode plates are bonded with the sensitive chip through silicon-silicon fusion, thus problems of thermal expansion coefficient mismatching and the like can be reduced; the patterns of the mass block and the beams are formed on the surface of the silicon slice through a double-layer SiO2 process, thus deep-groove photoetching is avoided. The eight-beam symmetrical silicon micro-accelerometer provided by the invention is high in stability, low in device noise, and capable of improving the measurement accuracy of the accelerometer.
Description
Technical field
The invention belongs to technical field of microelectronic mechanical systems, be specifically related to the symmetrical silicon micro accerometer of a kind of eight beams, this accelerometer precision is high, and the linearity is good, and long-time stability are good.
Background technology
The growing demand to the micro-acceleration gauge of high precision and high stability (μ g magnitude) in the markets such as navigational system, petroleum prospecting, gravity gradient meter, seismic monitoring is more and more stronger.Towards the various micro-acceleration gauges of high precision and high stability just in development development, wherein the accelerometer of silicon micro-capacitive has the advantages such as high sensitivity, good noiseproof feature, low drift, low temperature sensitivity, so accounted for sizable part in the research of accelerometer field silicon micro-capacitive accelerometer.
The basic functional principle of silicon micro-capacitive accelerometer is on mass-cantilever beam structure basis, coordinate upper and lower battery lead plate, produce variable capacitance part, when producing capacitance variations due to extraneous acceleration effect, by Weak Signal Detecting Circuit, read the variable quantity of electric capacity, can describe corresponding extraneous accekeration.Through demarcating and curve can be set up output signal and by the funtcional relationship between measuring acceleration, thereby measure extraneous acceleration." mass-semi-girder " structure normal open over etching technique forms.In order to produce thinner beam, often keep away not open the techniques such as deep trouth photoetching.Like this, thereby one side has increased technology difficulty, reduce yield rate, be difficult on the other hand obtain the mass that quality is larger, affected the raising of accelerometer performance.For general " mass-semi-girder " structure, the center of gravity of mass is not the center of gravity of total, so the coupling part stress of semi-girder and stiff end is very concentrated, has greatly affected the long-time stability of accelerometer.Because structure is asymmetric, mechanical thermal noise and the reason such as mass weight is limited, all there are some problems in micro-acceleration gauge at present aspect Linearity and precision.
Summary of the invention
The object of this invention is to provide a kind of symmetrical silicon micro accerometer of eight beams with balance movable structure, the precision of the symmetrical silicon micro accerometer of eight beams of the present invention can reach μ g magnitude, and output stability reaches drift μ g magnitude per hour.
The present invention is achieved by the following technical solutions.
The symmetrical silicon micro-capacitive accelerometer of eight beams of the present invention, is characterized in that, the symmetrical micro-acceleration gauge of eight described beams comprises silicon pole plate, sensitive chip, lower silicon electrode plate from top to bottom successively.Wherein, sensitive chip comprises that the polygon mass of sense accelerations is identical with eight root architectures, around the symmetrical thin thin parallelogram semi-girder of polygon mass.Upper and lower silicon electrode plate is closed and is connected by silicon-silicon bond with sensitive chip, forms self-enclosed system, and impermeability is good.Sensitive chip and upper and lower silicon electrode plate are realized contraposition by through hole separately.
Mass thickness is consistent with adopted silicon chip, is shaped as polygon and utilizes space to imitate, and makes quality obtain large increase, can obtain less device noise and larger sensitivity.
The first semi-girder in described sensitive chip, the second semi-girder, the 3rd semi-girder, the 4th semi-girder, the 5th semi-girder, the 6th semi-girder, the 7th semi-girder, the 8th cantilever beam structure are identical, xsect is parallelogram sturcutre, the long-diagonal of parallelogram is consistent with the Width of semi-girder, the short diagonal of parallelogram is consistent with the thickness direction of semi-girder, and thickness is 0.3～0.5 with the ratio of width.
The first semi-girder, the second semi-girder, the 3rd semi-girder, the 4th semi-girder, the 5th semi-girder, the 6th semi-girder, the 7th semi-girder, the 8th semi-girder and mass have the same central plane at thickness direction, are convenient to discharge stress and improve long term device stability.
The length direction of the first semi-girder, the second semi-girder, the 3rd semi-girder, the 4th semi-girder is consistent, the length direction of the 5th semi-girder, the 6th semi-girder, the 7th semi-girder, the 8th semi-girder is consistent, and the length direction of front four semi-girders and rear four semi-girders is orthogonal.
The thickness of described semi-girder and the Thickness Ratio of mass are 0.04～0.06.
The manufacturing process of the symmetrical silicon micro accerometer of eight beams of the present invention, comprises the following steps that (wherein step a-d is used for making sensitive chip successively; Step e is used for making upper and lower silicon electrode plate):
(a). two-sided oxidized silicon chip for the first time, dual surface lithography produces mass and frame figure;
(b). two-sided oxidized silicon chip for the second time, dual surface lithography produces semi-girder figure, the now SiO on semi-girder
2thickness is less than the SiO on mass and frame
2thickness;
(c). adopt tetramethyl ammonium hydroxide solution corrosion of silicon, corrosion depth is 1/4 of mass thickness;
(d). adopt BHF to remove the SiO on semi-girder
2, then adopt tetramethyl ammonium hydroxide solution corrosion of silicon to break-through, remove the SiO on mass and frame
2;
(e). oxidation growth SiO on silicon electrode plate
2insulation course, by photoetching and erosion removal battery lead plate and the SiO of sensitive chip moving part correspondence position
2;
(f). sensitive chip and upper and lower silicon electrode plate are carried out to silicon-silicon melting bonding;
(g). on upper and lower pole plate, evaporation forms metal electrode.
Silicon chip in the making step of the symmetrical silicon micro accerometer of eight beams of the present invention is the monocrystalline silicon silicon chip of N-type 1～10 Ω cm.
The principle of work of the symmetrical silicon micro accerometer of eight beams of the present invention is: under inertial acceleration effect, when the polygon mass on sensitive chip moves to a certain side silicon pole plate, the electric capacity of mass and two pole plates increases respectively and reduces, and detects the size of this differential capacitance just can know the size of acceleration by peripheral circuit.
Micro-acceleration gauge advantage of the present invention is:
1. entire infrastructure adopts tetramethyl ammonium hydroxide solution corrosion to form; the metallic ion of not only having avoided conventional KOH corrosion to introduce; there is the circuit compatibility with IC; and the protection for polygon mass salient angle place is very good in the situation that not needing collocation structure, this technological operation is simple, can batch making, cost is low.
2. adopt the corrosion rate of tetramethyl ammonium hydroxide solution low, so physical dimension is controlled well, reproducible, yield rate is high.
3. all oxidations and photoetching process all directly complete in wafer surface, and without deep trouth photoetching, simple to operate, yield rate is high.
4. whole technological process all adopts wet chemistry process, not affected by irradiation and without charge accumulated, is conducive to the long-time stability of micro-acceleration table.
5. silicon electrode plate and sensitive chip, by silicon-silicon melting bonding, can reduce the unmatched problem of thermal expansivity, and form airtight encapsulation certainly, have improved the long-time stability of device.
6. the thickness of polygon mass and the consistency of thickness of silicon chip, quality has obtained large increase, can obtain less device noise, has improved acceleration analysis precision.
7. can need to adjust the size of mass and the shape of semi-girder according to range and precision, increase the dirigibility of design.
8. because eight semi-girders are symmetric position quality of connection piece and framework, mass is horizontal, not only good at design range ability internal linear degree, and there is no outstanding stress concentration point, has reduced internal stress, has improved the long-time stability of device.
9. adopt the identical semi-girder dead center of eight root architectures mass, structural symmetry, transversal effect reduces greatly.
Accompanying drawing explanation
Fig. 1 is the symmetrical silicon micro accerometer structural representations of eight beams of the present invention;
Fig. 2 is that the sensitive chip in the present invention is prepared schematic diagram;
Fig. 3 is oxidized out oxide layer for the first time in monocrystalline silicon piece both sides in the present invention;
Sensitive chip frame in Fig. 4 the present invention and mass profile;
Silicon chip exposed part both sides in Fig. 5 the present invention are oxidized out compared with thin oxide layer for the second time;
Passing through photoetching and corroding in Fig. 6 the present invention produces beam profile schematic diagram;
The not protected part silicon thickness of two-sided corrosion in Fig. 7 the present invention is to mass 3/4ths schematic diagram;
In Fig. 8 the present invention, eight SiO above beam are removed in rinsing
2;
In Fig. 9 the present invention, corrode break-through silicon chip;
In Figure 10 the present invention, remove the SiO on frame and mass
2;
Silicon electrode plate insulation course SiO in Figure 11 the present invention
2form schematic diagram;
The corresponding SiO of silicon electrode plate sensitive chip moving part in Figure 12 the present invention
2remove schematic diagram;
In figure, 1. go up 231 to 238. eight semi-girder 201. sensitive chip monocrystalline silicon piece 202.SiO of 3. times silicon electrode plates of silicon electrode plate 2. sensitive chip, 21. sensitive chip frame 22. polygon masses
2101.-electric pole plate silicon chip 102-. insulation course SiO
2.
Embodiment
Fig. 1 is the symmetrical silicon micro accerometer structural representations of eight beams of the present invention, comprises electric pole plate 1, sensitive chip 2 and lower electrode plate 3 three parts, realizes the wafer level packaging of whole chip by silicon-silicon melting bonding.In sensitive chip inside, be provided with the polygon mass of perception inertial acceleration, mass surrounding symmetrical eight root architectures identical, be positioned at the semi-girder of polygon mass thickness direction central plane, mass is connected on frame by semi-girder; Between silicon electrode plate and sensitive chip, by silicon dioxide insulator, by silicon-silicon melting bonding, connect.Semi-girder cross section is parallelogram, and the lenth ratio scope of parallelogram long-diagonal and short diagonal is 1-10.Semi-girder is 0.01-0.2 in thickness and the mass thickness ratio scope of mass thickness direction.Upper silicon electrode plate, sensitive chip, lower silicon electrode plate are used silicon wafer to manufacture, and silicon chip is the monocrystalline silicon of N-type 1～10 Ω cm.
Now, in conjunction with instantiation and accompanying drawing, preparation technology's flow process of each several part is described in further detail.
Sensitive chip is symmetrical eight beams-polygon mass block structure, and as shown in Figure 1, concrete preparation technology's flow process (is illustrated as A-A to its vertical view as follows
'sectional view):
1) choose menu crystal silicon chip 201, adopt conventional oxidation technology, silicon chip both sides generate SiO
2oxide layer 202, as shown in Figure 2;
2) bilateral light carves after sensitive chip frame and mass figure with BHF solution rinsing SiO
2, the region that so far frame and mass are corresponding is by SiO
2protect, as shown in Figure 3;
3), after step 2 is processed, the silicon chip bilateral oxidation exposing generates thinner SiO
2, frame and SiO corresponding to mass position
2further thicken, as shown in Figure 4;
4) at thinner SiO
2bilateral light carves after eight beam figures with hydrofluoric acid solution rinsing SiO
2, the region that so far frame and mass and beam are corresponding is all by SiO
2protect, as shown in Figure 5;
5) adopt tetramethyl ammonium hydroxide solution corrosion of silicon, corrosion depth is about 1/4 of mass thickness, and because tetramethyl ammonium hydroxide solution corrosion speed is slow, the thickness of corrosion is easily controlled, as shown in Figure 6;
6) with the SiO on hydrofluoric acid solution rinsing silicon chip
2until the SiO on beam
2disappear completely, due to the SiO on mass and frame
2thicker so be not completely removed, still possess protective effect, as shown in Figure 7;
7) adopt tetramethyl ammonium hydroxide solution corrosion of silicon, until break-through, now beam, mass and frame all form, as shown in Figure 8;
8) SiO improving quality on piece and frame with hydrofluoric acid solution rinsing silicon chip
2, sensitive chip completes, the beam diamondwise of producing, as shown in Figure 9.
Because manufacture craft and the size of upper and lower silicon electrode plate are basically identical, the top crown of only take is here described preparation technology's flow process of upper and lower fixed plate electrode as example, as follows in detail:
1) menu crystal silicon chip 101, at itself and oxidation growth 2um thick dielectric layer silica 1 02 of sensitive chip bonding, as shown in figure 10;
2) then at SiO
2on revolve way photoresist, machine glazing carve with sensitive chip moving part graph of a correspondence after with hydrogen fluorine solution corrosion, remove the SiO of graphics field
2, form battery lead plate as shown in figure 11.
Claims (4)
1. the symmetrical silicon micro accerometer of eight beams, is characterized in that: described micro-acceleration gauge comprises silicon electrode plate, sensitive chip, lower silicon electrode plate three parts from top to bottom successively; Three parts form a self-enclosed system by silicon-silicon bonding; In sensitive chip inside, be provided with the polygon mass of perception inertial acceleration, mass surrounding symmetrical eight root architectures identical, be positioned at the semi-girder of polygon mass thickness direction central plane, mass is connected on frame by semi-girder; Between silicon electrode plate and sensitive chip, by silicon dioxide insulator, by silicon-silicon melting bonding, connect.
2. micro-acceleration gauge according to claim 1, is characterized in that: semi-girder cross section is parallelogram, and the lenth ratio scope of parallelogram long-diagonal and short diagonal is 1-10.
3. micro-acceleration gauge according to claim 1, is characterized in that: semi-girder is 0.01-0.2 in thickness and the mass thickness ratio scope of mass thickness direction.
4. micro-acceleration gauge according to claim 1, is characterized in that: upper silicon electrode plate, sensitive chip, lower silicon electrode plate are used silicon wafer to manufacture, and silicon chip is the monocrystalline silicon of N-type 1～10 Ω cm.
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|---|---|---|---|
| CN201410447900.0A CN104198762A (en) | 2014-09-04 | 2014-09-04 | Eight-beam symmetrical silicon micro-accelerometer |
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|---|---|---|---|
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841683A (en) * | 2017-04-06 | 2017-06-13 | 中国工程物理研究院电子工程研究所 | Quartz pendulous accelerometer and preparation method thereof |
| CN107782915A (en) * | 2017-09-29 | 2018-03-09 | 中国人民解放军国防科技大学 | Silicon hollow beam, silicon micro-accelerometer based on silicon hollow beam and preparation method of silicon micro-accelerometer |
| CN108344881A (en) * | 2018-02-10 | 2018-07-31 | 中国工程物理研究院电子工程研究所 | A kind of sensitive structure of closed loop micro-acceleration gauge |
| CN108828265A (en) * | 2018-07-25 | 2018-11-16 | 中国工程物理研究院电子工程研究所 | A kind of capacitance type micro mechanical acceleration transducer |
| CN112881755A (en) * | 2021-01-19 | 2021-06-01 | 西北工业大学 | Broadband response silicon micro-mechanical accelerometer with high vibration stability |
-
2014
- 2014-09-04 CN CN201410447900.0A patent/CN104198762A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841683A (en) * | 2017-04-06 | 2017-06-13 | 中国工程物理研究院电子工程研究所 | Quartz pendulous accelerometer and preparation method thereof |
| CN106841683B (en) * | 2017-04-06 | 2023-09-01 | 中国工程物理研究院电子工程研究所 | Quartz pendulum accelerometer and preparation method thereof |
| CN107782915A (en) * | 2017-09-29 | 2018-03-09 | 中国人民解放军国防科技大学 | Silicon hollow beam, silicon micro-accelerometer based on silicon hollow beam and preparation method of silicon micro-accelerometer |
| CN107782915B (en) * | 2017-09-29 | 2020-07-17 | 中国人民解放军国防科技大学 | Silicon hollow beam, silicon micro-accelerometer based on silicon hollow beam and preparation method of silicon micro-accelerometer |
| CN108344881A (en) * | 2018-02-10 | 2018-07-31 | 中国工程物理研究院电子工程研究所 | A kind of sensitive structure of closed loop micro-acceleration gauge |
| CN108344881B (en) * | 2018-02-10 | 2020-04-03 | 中国工程物理研究院电子工程研究所 | Sensitive structure of closed-loop micro-accelerometer |
| CN108828265A (en) * | 2018-07-25 | 2018-11-16 | 中国工程物理研究院电子工程研究所 | A kind of capacitance type micro mechanical acceleration transducer |
| CN112881755A (en) * | 2021-01-19 | 2021-06-01 | 西北工业大学 | Broadband response silicon micro-mechanical accelerometer with high vibration stability |
| CN112881755B (en) * | 2021-01-19 | 2022-06-14 | 西北工业大学 | Broadband response silicon micro-mechanical accelerometer with high vibration stability |
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