CN102778586B - Differential capacitive micro-acceleration transducer and manufacturing method thereof - Google Patents
Differential capacitive micro-acceleration transducer and manufacturing method thereof Download PDFInfo
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- CN102778586B CN102778586B CN201210287128.1A CN201210287128A CN102778586B CN 102778586 B CN102778586 B CN 102778586B CN 201210287128 A CN201210287128 A CN 201210287128A CN 102778586 B CN102778586 B CN 102778586B
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Abstract
The invention discloses a differential capacitive micro-acceleration transducer and a manufacturing method thereof. According to the method, the manufacturing of a movable mass block and an elastic beam is completed by using a bulk-silicon process, and the structure manufacturing and the releasing of a device structure are simultaneously completed by using a dry etching method; a movable electrode and the movable mass block are same in shape and size, so that an operation of repeated photoetching is avoided, thereby greatly simplifying the process; the stiffness of the designed elastic beam is small in the sensitive direction and large in the sensitive vertical direction, therefore, the elastic beam is higher in selectivity and anti-crosstalk capacity; and a device is simply and reliably packaged by using a wafer-level low-temperature vacuum aligned-bonding technology, thereby facilitating the large-scale manufacturing of the device. In addition, the differential capacitive micro-acceleration transducer disclosed by the invention adopts a variable-area type operating principle, so that the movable mass block is only damped by a sliding membrane in the process of moving, thereby improving the sensitivity.
Description
Technical field
The present invention relates to a kind of acceleration transducer, particularly relate to little grating structure differential capacitance micro-acceleration sensor to millimeter magnitude of a kind of manufacture method simple Devices size and preparation method thereof, belong to Microelectron-machine field.
Background technology
Miniature acceleration sensor is extensive being applied in the fields such as space guidance, vehicle control, robot, cell phone intelligent, industry mine locating, medical science with features such as its volume are little, lightweight, power consumption is little, cost is low, easy of integration.In order to adapt to the restriction of different field measuring condition, the type of acceleration transducer is also varied, but capacitance acceleration transducer due to its good temperature characterisitic, high sensitivity, stability is high and process the main direction that the feature such as simple always is research.
The sensitive mechanism that is applied to micro-acceleration sensor is a lot, and what have at present bibliographical information mainly contains pressure resistance type, condenser type, temperature sensitive formula, resonant mode etc.Piezoresistive micro-accelerometer is by movable mass induction acceleration, input is converted to the deformation of elastic construction, thereby cause the variation of the voltage dependent resistor (VDR) resistance being produced on elastic construction, then by external circuitry, the variation of resistance is converted to voltage or curent change.The advantages such as it is simple that piezoresistance type acceleration sensor has processing technology, and measuring method is easy, and the linearity is good, but also have serious shortcoming, for example temperature effect is serious, unstable working condition, and sensitivity is low etc.
Condenser type micro-acceleration sensor is by movable mass induction acceleration, utilizes parallel plate capacitor the relative displacement of mass to be converted to the variation of electric capacity, then the subtle change of electric capacity is converted to the variation of the voltage being proportional by testing circuit.Capacitance acceleration transducer has the outstanding advantages such as temperature effect is low, power consumption is little, sensitivity is relatively high, simple in structure, but extraneous acceleration only can cause the variation that electric capacity is small (conventionally even lower in 10-15 magnitude), so method of testing is complicated.For capacity plate antenna, capacitance is:
The specific inductive capacity that wherein ε is medium, A be pole plate over against area, d is vertical range between pole plate.
From above formula, capacitance acceleration sensor is roughly divided into two classes by principle of work.One class is to become space type, and under the effect of acceleration, mass upper/lower electrode distance changes, and in most of documents, adopting is more the acceleration transducer that becomes space type; Another kind of is variable area formula, and the parallel misalignment by upper/lower electrode changes overlapping area.The former,, due to electric capacity and the spacing relation that is inversely proportional to, can cause the non-linear of capacitance variations, need to utilize feedback circuit to reduce non-linear, due to upper bottom crown relative motion, can produce larger press-filming damping in addition.The latter is linear relation completely, and is slide-film damping due to what produce in motion process, and this has improved the sensitivity of accelerometer greatly.
Given this, how to produce a kind of condenser type micro-acceleration sensor, to overcome the shortcoming of the small method of testing complexity causing of capacitance variations non-linear and that acceleration causes of capacitance variations in prior art, become current problem demanding prompt solution.
Summary of the invention
The shortcoming of prior art in view of the above, the object of the present invention is to provide a kind of differential capacitance micro-acceleration sensor and preparation method thereof, for solving the problem of the non-linear of prior art capacitance variations and the small method of testing complexity causing of capacitance variations that acceleration causes.
For achieving the above object and other relevant objects, the invention provides a kind of differential capacitance micro-acceleration sensor and preparation method thereof, at least comprise the following steps:
1) provide a substrate, in the front of described substrate, prepare metal level, and on described metal level, carry out photoetching and etching process is produced a pair of interdigitated fixed electorde and two fixed electorde contacts;
2) provide a structure substrate, and at described structure substrate back, carry out photoetching and etching process and prepare for discharging preset cavity and two electrodes of movable structure and draw through hole;
3) by front and the step 2 of substrate described in step 1)) described in the back side of structure substrate be bonded together;
4) from described structure substrate front, be thinned to target thickness, at its front depositing metal layers, and on described metal level, carry out photoetching and etching process and form the figure that movable electrode, movable mass, elastic beam and fixed electorde are drawn through-hole structure;
5) litho pattern foundation described rapid 4), draws through hole by described structure substrate being carried out to dry etching to obtain movable mass, elastic beam and two electrodes;
6) provide a cover plate substrate, at described cover plate substrate back, carry out photoetching and etching process is produced the cover plate cavity corresponding with described movable mass;
7) front of structure substrate in the cover plate substrate back in described step 6) and described step 5) is bonded together;
8) on the cover plate substrate of the deep etch technique by photoetching and silicon in described step 7), form electrode and draw through hole;
9) by routing mode, from described electrode, draw and through hole, draw fixed electorde and movable electrode.
Alternatively, in described step 4), the material at the positive metal level depositing of described structure substrate is Au, Al, Cu or Ag; Bonding technology in described step 7) is wafer-level low-temperature vacuum bonding, and the bonding material of employing is glass paste, polymkeric substance or metal-to-metal adhesive; Described step 2) in, the on-chip electrode of structure is drawn through hole and the on-chip electrode of described step 5) cover plate and is drawn through hole and align, for described fixed electorde and movable electrode are drawn; When the substrate in described step 1) is glass sheet, the material of the metal level depositing on described glass sheet in this step 1) is Au, Al, Cu or Ag; In described step 3), adopt anode linkage technique that the back side of substrate face and described structure substrate is bonded together.
Alternatively, when the substrate in described step 1) is silicon chip, described step 1) also comprises:
1-1) provide a substrate, at the front of described substrate thermal oxide growth one deck monox;
1-2) at described step 1-1) front of substrate prepares Au layer, and on described Au layer, carry out photoetching and etching process is produced a pair of interdigitated fixed electorde;
Described step 2) also comprise:
2-1) provide a structure substrate, and at described structure substrate back thermal oxide growth one deck monox;
2-2) at described step 2-1) monox on carry out photoetching and etching process and produce for discharging preset cavity and the electrode of movable structure and draw through hole;
2-3) at described structure substrate back, make bonding contact ring.
Alternatively, described step 2-3), the material of bonding contact ring is glass paste, polymkeric substance or metal-to-metal adhesive.
Alternatively, described structure substrate is silicon chip or SOI substrate; Described cover plate substrate is silicon chip.
Alternatively, when described structure substrate is SOI substrate, described step 2) also comprise:
2-1) provide a structure substrate, at top layer silicon Film by Thermal Oxidation one deck monox of described structure substrate back;
2-2) on the silicon oxide layer of described structure substrate back, carry out photoetching and etching, output the corrosion window of described top layer silicon, then take monox as mask, the top layer silicon of described corrosion window is carried out to etching until reach buried regions silicon oxide layer, to form for discharging preset cavity and the electrode of movable structure, draw through hole;
2-3) utilize dry etching by described step 2-2) in the described buried regions monox that exposes of structure substrate back etch away.
Another object of the present invention is to provide a kind of differential capacitance micro-acceleration sensor, at least comprises:
Substrate, its front has a pair of interdigitated fixed electorde and pair of stationary electrodes contact;
Structure substrate, the back side with a cavity is bonded on described substrate, by this cavity and described substrate surface, forms electric capacity spacing, and front has palisade movable electrode; Corresponding described cavity top is hung with palisade movable mass, and described movable mass both sides are connected to described structure substrate by some symmetrical elastic beams respectively; On corresponding described substrate, a pair of described fixed electorde contact also has two electrodes and draws through hole on described structure substrate;
Cover plate substrate, the back side with a cavity is bonded on described structure substrate front, has consisted of the movement clearance of described movable quality this cavity and described structure substrate front; A pair of described fixed electorde contact and the on-chip movable electrode of structure on corresponding described substrate also have two electrodes and draw through hole on described cover plate substrate, to realize, described fixed electorde and movable electrode are drawn.
Alternatively, the material of described fixed electorde and movable electrode is Au, Al, Cu or Ag; Described elastic beam and movable mass are formed in described structure substrate body material; Described elastic beam is symmetrically distributed in described movable mass both sides, and its number is 2, and described elastic beam be shaped as annular; The on-chip palisade movable mass of interdigitated fixed electorde on described substrate and structure forms sensitization capacitance device; The direction of motion of the palisade movable mass in described acceleration transducer is along the direction parallel with this mass upper surface, belongs to acceleration transducer in face.
Alternatively, described substrate is elected silicon chip or glass sheet as; Described structure substrate is for electing silicon chip or SOI substrate as; Described cover plate substrate is elected silicon chip as; When described structure substrate is SOI substrate, described electric capacity spacing is the thickness sum of this SOI substrate top layer silicon and buried regions monox; Described cyclic spring beam and movable mass are formed in the substrate silicon of this SOI substrate.
As mentioned above, a kind of differential capacitance micro-acceleration sensor of the present invention and preparation method thereof, has following beneficial effect:
The present invention utilizes bulk silicon technological to complete the making of movable mass and elastic beam, also completes the release of device architecture when completing structure fabrication by dry etching; Movable electrode and movable mass are of similar shape and size, avoid repetition photoetching, and technique is simplified greatly; The elastic beam of design is little in sensitive direction rigidity, and responsive vertical direction rigidity is large, has higher selectivity and anti-crosstalk ability; Utilize wafer-level low-temperature vacuum aim at bonding techniques by device simple and reliable be encapsulated, be convenient to extensive manufacture.In addition, micro-acceleration sensor of the present invention has adopted variable area formula principle of work to make movable mass when motion, only be subject to slide-film damping, improved sensitivity, and adopted palisade movable electrode and interdigital fixed electorde to make under same acceleration effect, to produce larger capacitance change, further reduced the detection difficulty of differential type electric capacity.Therefore, differential capacitance type micro-acceleration sensor of the present invention is simple in structure, and technique is easy to realize, and measuring accuracy is high, the linearity good, highly sensitive, is a kind of practicable solid-state micro accelerometer.
Accompanying drawing explanation
Fig. 1 a～1i is shown as the differential capacitance micro-acceleration sensor fabrication processing schematic diagram in the embodiment of the present invention one.
Fig. 2 a～2e is shown as the differential capacitance micro-acceleration sensor preparing department division technique schematic flow sheet in the embodiment of the present invention two.
Fig. 3 a～3d is shown as the differential capacitance micro-acceleration sensor preparing department division technique schematic flow sheet in the embodiment of the present invention three.
Fig. 4 is shown as the differential capacitance micro-acceleration sensor structural representation in the embodiment of the present invention four.
Fig. 5 a～5b is shown as equivalent electrical circuit and the principle of work schematic diagram of the differential capacitance micro-acceleration sensor in the embodiment of the present invention four
Element numbers explanation
1 substrate
2,4 metal levels
20 interdigitated fixed electordes
21 fixed electorde contacts
3 structure substrates
30 preset cavitys
31,51 electrodes are drawn through hole
32 palisade movable mass
33 elastic beams
34 top layer silicon
35 buried regions monox
36 substrate silicon
40 movable electrodes
5 cover plate substrates
50 cover plate cavitys
6 glass paste bondings
7 fixed electorde lead-in wires
8 movable electrode lead-in wires
9 silicon oxide layers
10 bonding contact rings
S1 ~ S9 step
AB, C direction
Embodiment
Below, by specific instantiation explanation embodiments of the present invention, those skilled in the art can understand other advantages of the present invention and effect easily by the disclosed content of this instructions.The present invention can also be implemented or be applied by other different embodiment, and the every details in this instructions also can be based on different viewpoints and application, carries out various modifications or change not deviating under spirit of the present invention.
It should be noted that, the diagram providing in the present embodiment only illustrates basic conception of the present invention in a schematic way, satisfy and only show with assembly relevant in the present invention in graphic but not component count, shape and size drafting while implementing according to reality, during its actual enforcement, kenel, quantity and the ratio of each assembly can be a kind of random change, and its assembly layout kenel also may be more complicated.
Refer to Fig. 1 a～1i, Fig. 2 a～2e, Fig. 3 a～3d, Fig. 4 and Fig. 5 a～5b, in conjunction with Figure of description, further illustrate a kind of differential capacitance type micro-acceleration sensor provided by the invention and preparation method thereof, the different substrates that provide according to the present invention and different structure substrates, the method for making of described acceleration transducer is also slightly different, below by different embodiment, is elaborated.
Embodiment mono-
As described in Fig. 1 a to 1i, the present embodiment provides a kind of method for making of differential capacitance micro-acceleration sensor, comprises the following steps:
Step S1: as shown in Figure 1a, one glass substrate 1 is provided, in the front of described glass substrate 1, passes through electron beam evaporation or evaporation layer of metal layer 2, the material of this metal level 2 is elected Au temporarily as, but be not limited to this, also can be in other embodiments the conducting metals such as Al, Cu or Ag; Then on described metal level 2, carry out photoetching and etching process and produce a pair of interdigitated fixed electorde 20 and two fixed electorde contacts 21.
Step S2: a structure substrate 3 is provided, and in the present embodiment, described structure substrate is elected silicon chip temporarily as, but is not limited to this, also can be in other embodiments other substrate, and different structure substrate technique is difference slightly; Then at described structure substrate 3 back sides, carry out that photoetching forms preset cavity 30 and electrode is drawn through hole 31 figures, then utilize dry method or wet corrosion technique to prepare for discharging the preset cavity 30 of movable structure and the structure that two electrodes are drawn through hole 31, the degree of depth of this preset cavity 30 is the electric capacity spacing of described micro-acceleration sensor, and this electric capacity spacing changes according to the difference of the performance of the acceleration transducer of made.Be the sectional view of described structure silicon chip as shown in Figure 1 b.
Step S3: adopt anode linkage technique that the back side of structure substrate 3 described in the front of glass substrate 1 in described step S1 and described step S2 is bonded together, anode linkage technique is generally only limited to glass-silicon bonding, bonding temperature is 300 ℃～400 ℃, and bias voltage is 500V～1000V.It should be noted that, when bonding, on the position of the corresponding described metal electrode lead-in wire of described structure substrate 3, erode away a loculus (not shown), described structure silicon chip 3 back sides can not be contacted with the metal electrode lead-in wire on described substrate 1 silicon chip, as Fig. 1 c is depicted as the sectional view after bonding.
Step S4: adopt chemical mechanical milling method or wet corrosion technique to carry out attenuate from described structure substrate 3 fronts, be thinned to after target thickness, by evaporation or electron beam evaporation process, in structure substrate 3 fronts of described attenuate, deposit layer of metal layers 4, in the present embodiment, the material of this metal level 4 is elected Au as, but be not limited to this, also can be in other embodiments the conducting metals such as Al, Cu or Ag; Then just photoetching on described metal level 4, and to its corrode to form respectively movable electrode 40, palisade movable mass 32(is called for short movable mass 32), elastic beam 33 and fixed electorde draw the figure of through hole 31 structures; It is corresponding in vertical direction with the fixed electorde contact 21 in described step S1 that described electrode is drawn the figure of through hole 31 structures, so that corrode fixed electorde that described structure substrate 3 forms in subsequent step, draws through hole 31 and can be communicated with this fixed electorde contact 21; The metal level 4 of described movable mass 32 superstructures is as movable electrode 40, the place that described structure substrate 4 fronts are not covered by metal level 4 will be corroded in subsequent step, and on this structure substrate 3, remaining metal level 4 is realized electricity with the movable electrode 40 on movable mass 32 and is connected.Fig. 1 d is shown as the structure graph planimetric map carrying out on the metal level of described structure front side of silicon wafer after photoetching.
Step S5: according to the litho pattern in described rapid S4, by drawing through hole 31 to not carried out dry etching by the structure substrate 3 covering described in described metal level 4 to obtain movable mass 32, elastic beam 33 and two electrodes.Described movable mass 32 is grating structure, and its both sides are connected to described structure silicon chip 3 by some symmetrical elastic beams 33 respectively.It should be noted that, the present embodiment Elastic beam 33 be shaped as annular, quantity is 2, but be not limited to this, the form of described elastic beam 32 changes according to the performance of described acceleration transducer is different with quantity in other embodiments, such as the shape of described elastic beam 33, can be shape of straight beam or other symmetrical structure etc., quantity can be 4,6 etc.As Fig. 1 e is depicted as along the sectional view of the AB direction of Fig. 1 d, in the sectional view structure of subsequent technique process flow diagram, be all the AB direction in device architecture according to Fig. 1 d(or Fig. 1 d) the cross section of AB direction, in subsequent step, do not repeating, hereby statement.
Step S6: as shown in Figure 1 f, provide one at cover plate substrate 5, the present embodiment cover plate substrate 5 is elected silicon chip as, but be not limited to this, in other embodiment, also can be other substrate, such as Ge substrate etc., at described cover plate substrate 5 back sides, carry out after photoetching, utilize dry method or wet corrosion technique to erode away the cover plate cavity 50 corresponding with described movable mass, by this cover plate cavity 50 and described structure substrate 3 fronts, formed the movement clearance of described movable mass 32.
Step S7: as shown in Figure 1 g, adopt wafer-level low-temperature Vacuum Package glass paste bonding 6 techniques that the front of structure substrate 3 in cover plate substrate 5 back sides in described step S6 and described step S5 is bonded together, glass paste bonding 6 technology have that technique is simple, bond strength is high, good sealing effect, production efficiency advantages of higher, are a kind of high yield, encapsulation technology cheaply.But be not limited to the bonding technology in the present embodiment, can also adopt in other embodiments wafer-level low-temperature Vacuum Package polymer-bound technique or metal-to-metal adhesive bonding technology etc.By the cover plate substrate 5 of bonding, realized the wafer-level vacuum package of described acceleration transducer, to prevent that movable structure in described acceleration transducer is subject to the impact of the factors such as dust in scribing and assembling process, steam, causes the breaking-up of device or the decline of overall performance.
It should be noted that, after described cover plate substrate 5 and structure silicon chip 3 bondings, cover plate cavity 50 on this cover plate silicon chip 5 just in time covers on the movable mass 32 and elastic beam 33 on described structure substrate 3, and has formed the free movement space of movable mass 32 with structure substrate 3 fronts.
Step S8: as shown in Fig. 1 h, cover plate substrate 5 fronts after bonding are carried out photoetching and are drawn the corresponding electrode of through hole 51 structures with these cover plate substrate 5 backplates and draw through hole 51 figures to form, according to the figure of photoetching, and utilize dry method or wet-etching technology to etch electrode on described cover plate substrate 5 and draw through hole 51.Dry etching general using deep reaction ion etching technique, and wet etching adopts KOH solution to carry out the corrosion of silicon.
It should be noted that, electrode on described cover plate substrate 5 is drawn through hole 51 and is drawn through hole 31 with the electrode on structure substrate 3 and be connected in vertical direction, so that fixed electorde 20 is drawn, and be positioned at electrode on cover plate substrate 5 and draw through hole 51 metal lead wire on described structure substrate 3 is exposed, so that movable electrode 40 is drawn.
Step S9: as shown in Fig. 1 i, draw through hole 31 and 51 and draw fixed electorde lead-in wire 7 and movable electrode lead-in wire 8 from described electrode by routing mode, complete the making of condenser type micro-acceleration sensor.
In sum, the present invention utilizes bulk silicon technological to complete the making of movable mass and elastic beam, also completes the release of device architecture when completing structure fabrication by dry etching; The elastic beam of design is little in sensitive direction rigidity, and its responsive vertical direction rigidity is large, has higher selectivity, prevents from crosstalking; Adopted palisade movable electrode and interdigital fixed electorde to make under same acceleration effect, to produce larger capacitance change, and differential type capacitance detecting mode has further reduced detection difficulty; Utilize cryogenic vacuum bonding techniques to realize the wafer-level vacuum package of device; Adopt variable area formula differential capacitance principle of work, guarantee the good serviceability of device.In addition the utility model acceleration sensor structure is simple, and technique is easy to realize, and measuring accuracy is high, the linearity good, highly sensitive, is a kind of practicable solid-state micro accelerometer.
Embodiment bis-
2a to 2e is depicted as the part process chart of the making differential capacitance micro-acceleration sensor in the present embodiment as shown in the figure, the present embodiment provides the method for making of another kind of differential capacitance micro-acceleration sensor, with embodiment mono-difference be that the substrate providing in the present embodiment is silicon substrate, therefore, the difference of substrate has caused technologic difference a little, and the difference of concrete technology step is as follows:
When a silicon substrate 1 is provided, the step S1 of described embodiment mono-also comprises:
S1-1: as shown in Figure 2 a, provide a substrate 1, at the front of described silicon substrate thermal oxide growth one deck silicon oxide layer 9, this silicon oxide layer 9 is by 2 insulation of the metal level in described silicon substrate and subsequent step.
S1-2: as shown in Figure 2 b, by evaporation or electron beam evaporation process, on the silicon oxide layer 9 of described step S1-1 substrate, prepare layer of metal layer 2,2 materials of metal level described in the present embodiment are elected Au temporarily as, but be not limited to this, can also elect the conductive metallic materials such as Al, Cu or Ag as in other embodiments.Then on described metal level 2, carry out photoetching and etching process and produce a pair of interdigitated fixed electorde 20 and two fixed electorde contacts 21.Be the planimetric map that described substrate forms fixed electorde as shown in Figure 2 b.
A kind of step S2 of described embodiment also comprises:
S2-1: as shown in Figure 2 c, provide a structure substrate 3, the structure substrate 3 in the present embodiment is elected silicon chip temporarily as, then at described structure substrate 3 back side thermal oxide growth one deck monox 9.
S2-2: carry out on described structure substrate 3 back side silicon oxide layers 9 that photoetching forms preset cavity 30 and electrode is drawn through hole 31 figures, then utilize dry method or wet corrosion technique to prepare for discharging the preset cavity 30 of movable structure and the structure that two electrodes are drawn through hole 31, what the degree of depth of this preset cavity 30 was described micro-acceleration sensor can dynamic condenser spacing, and this electric capacity spacing changes according to the difference of the performance of the acceleration transducer of made.Be the sectional view of structure substrate as shown in Figure 2 d.
S2-3: make bonding contact ring 10 on described structure substrate 3 back sides and substrate face silicon oxide layer 9, in the present embodiment, bonding contact ring 10 is elected Au-Au bonding ring temporarily as, but be not limited to this, in other embodiments, bonding contact ring 10 also can be glass paste, polymkeric substance or metal-to-metal adhesive.Be the sectional view of structure substrate as shown in Figure 2 d.
Other step and process chart in the present embodiment are identical with embodiment mono-, do not repeat them here.Be the structural drawing of the final acceleration transducer that forms in the present embodiment as shown in Figure 2 e.
Embodiment tri-
3a to 3d is depicted as the part process chart of the making differential capacitance micro-acceleration sensor in the present embodiment as shown in the figure, the present embodiment provides the method for making of another kind of differential capacitance micro-acceleration sensor, with embodiment mono-difference be that the structure substrate providing in the present embodiment is SOI substrate, therefore, the difference of structure substrate has also caused technologic difference a little, and the difference of concrete technology step is as follows:
When a soi structure substrate 3 is provided, the step S2 of described embodiment mono-also comprises:
S2-1: as shown in Figure 3 a, provide a structure substrate 3, the top layer silicon 36 Film by Thermal Oxidation one deck monox 9 at described structure substrate 3 back sides.
S2-2: as shown in Figure 3 b, on the silicon oxide layer 9 at described structure substrate 3 back sides, carry out photoetching and etching, output the corrosion window of described top layer silicon 36, then take silicon oxide layer 9 as mask, adopt dry method or wet corrosion technique to carrying out etching until reach buried regions monox 37 in the top layer silicon 36 of described corrosion window, preset cavity 30 and the electrode to form, be used for discharging movable structure are drawn through hole 31 structures, finally remove the monox 9 in described top layer silicon.
S2-3: as shown in Figure 3 c, the described buried regions monox 37 that utilizes dry etching that structure substrate 3 back sides in described step S2-2 are exposed etches away.
It should be noted that, the acceleration transducer of making by the method, electric capacity spacing can accurately be controlled, and is the thickness sum of this SOI substrate top layer silicon and buried regions monox; Described cyclic spring beam and movable mass are formed in the substrate silicon of this SOI substrate, and the thickness of described cyclic spring beam and movable mass also can accurately be controlled.
Other step and process chart in the present embodiment are identical with embodiment mono-, do not repeat them here.Be the structural drawing of the final acceleration transducer that forms in the present embodiment as shown in Figure 3 d.
Embodiment tetra-
As scheme institute 4 and show, another object of the present invention is to provide a kind of differential capacitance micro-acceleration sensor, is applied to, in the vacuum cavity environment of sealing, at least comprise substrate 1, structure substrate 3 and cover plate substrate 5.
Described substrate 1 is arranged at the bottom of described micro-acceleration sensor, substrate described in the present embodiment 1 is elected glass temporarily as, but be not limited to this, be also chosen as in other embodiments silicon chip or germanium wafer etc., its front has a pair of interdigitated fixed electorde 20 and pair of stationary electrodes contact 21.The material of fixed electorde described in the present embodiment 20 and fixed electorde contact 21 is elected Au temporarily as, but is not limited to this, is also chosen as in other embodiments Al, Cu or Ag.
The back side that described structure substrate 3 has a preset cavity 30 is bonded on described substrate 1, by this preset cavity 30 and described substrate 1 surface, forms electric capacity spacing, and front has palisade movable electrode 40; Corresponding described preset cavity 30 tops are hung with palisade movable mass 32, and described movable mass 32 both sides are connected to described structure substrate 3 by some symmetrical elastic beams 33 respectively; On corresponding described substrate 1, a pair of described fixed electorde contact 21 also has two electrodes and draws through hole 31 on described structure substrate 3.In the present embodiment, structure substrate 3 is elected silicon chip temporarily as, but is not limited to this, also can be in other embodiments soi structure substrate 3.When described structure substrate is SOI substrate, described electric capacity spacing is this structure substrate 3 top layer silicon 36 and the thickness sum of buried regions monox 35, and described elastic beam 33 and movable mass 32 are formed in the substrate silicon 34 of this structure substrate 3 (with reference to figure 3d).
It should be noted that, the present embodiment Elastic beam 33 be shaped as annular, quantity is 2, but be not limited to this, the form of described elastic beam 33 changes according to the performance of described acceleration transducer is different with quantity in other embodiments, such as the shape of described elastic beam 33, can be shape of straight beam or other symmetrical structure etc., quantity can be 4,6 etc.
The back side that described cover plate substrate 5 has a cover plate cavity 50 is bonded on described structure substrate 3 fronts, has consisted of the movement clearance of described movable quality 32 this cover plate cavity 50 and described structure substrate 3 fronts; Movable electrode 40 on corresponding described substrate 1 on a pair of described fixed electorde contact 21 and structure substrate 3 also has two electrodes and draws through hole 51 on described cover plate substrate 5, to realize, described fixed electorde 20 and movable electrode 40 is drawn.Cover plate substrate 5 in the present embodiment is elected silicon chip temporarily as, but is not limited to this, also can be in other embodiments germanium substrate etc.
It should be noted that, described micro-acceleration sensor structure applications is in the vacuum cavity environment of sealing, and the direction of motion of the palisade movable mass 32 in this micro-acceleration sensor is along the direction parallel with these mass 32 upper surfaces, belongs to acceleration transducer in face.
In order further to illustrate principle and the effect of differential capacitance micro-acceleration sensor of the present invention, refer to Fig. 5 a to 5b, as shown be the fundamental diagram of this acceleration transducer.
Described movable mass 32 in the present invention is the acceleration of detection level direction planar, has good selectivity.This movable mass 32 is one with movable electrode 30 simultaneously, the movable electrode 30 of grating structure can produce large capacitance variations with the fixed electorde 20 of interdigital structure under the state of little displacement, and become stricter linear relationship, by changing the number of movable mass 32 grid of the interdigital number of interdigital fixed electorde 20 and length and grating structure and the variation that length can continue to increase electric capacity.When movable mass 32 moves, can there is the identical positive and negative different variation of size from two groups of Detection capacitances that upper movable electrode 30 forms in lower fixed electorde 20.When the direction C in pressing Fig. 5 b moves, large if an electric capacity (C1) becomes, another one electric capacity (C2) just diminishes.By detecting the size of differential capacitance, just can extrapolate the size of acceleration.Visible accelerometer of the present invention relatively other accelerometers has larger output, the good linearity and less air damping, and the designing and making of follow-up interface circuit is also relatively simple.
In sum, a kind of differential capacitance micro-acceleration sensor that the present invention proposes and preparation method thereof, the method utilizes bulk silicon technological to complete the making of movable mass and elastic beam, also completes the release of device architecture when completing structure fabrication by dry etching; Movable electrode and movable mass are of similar shape and size, avoid repetition photoetching, and technique is simplified greatly; The elastic beam of design is little in sensitive direction rigidity, and responsive vertical direction rigidity is large, has higher selectivity and anti-crosstalk ability; Utilize wafer-level low-temperature vacuum aim at bonding techniques by device simple and reliable be encapsulated, be convenient to extensive manufacture.In addition, micro-acceleration sensor of the present invention has adopted variable area formula principle of work to make movable mass when motion, only be subject to slide-film damping, improved sensitivity, and adopted palisade movable electrode and interdigital fixed electorde to make under same acceleration effect, to produce larger capacitance change, and differential type capacitance detecting mode has further reduced detection difficulty.Therefore, differential capacitance type micro-acceleration sensor of the present invention is simple in structure, and technique is easy to realize, and measuring accuracy is high, the linearity good, highly sensitive, is a kind of practicable solid-state micro accelerometer.So the present invention has effectively overcome various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not for limiting the present invention.Any person skilled in the art scholar all can, under spirit of the present invention and category, modify or change above-described embodiment.Therefore, such as in affiliated technical field, have and conventionally know that the knowledgeable, not departing from all equivalence modifications that complete under disclosed spirit and technological thought or changing, must be contained by claim of the present invention.
Claims (9)
1. a method for making for differential capacitance micro-acceleration sensor, is characterized in that, at least comprises the following steps:
1) provide a substrate, in the front of described substrate, prepare metal level, and on described metal level, carry out photoetching and etching process is produced a pair of interdigitated fixed electorde and two fixed electorde contacts;
2) provide a structure substrate, and at described structure substrate back, carry out photoetching and etching process and prepare for discharging preset cavity and two electrodes of movable structure and draw through hole;
3) by front and the step 2 of substrate described in step 1)) described in the back side of structure substrate be bonded together;
4) from described structure substrate front, be thinned to target thickness, at its front depositing metal layers, and on described metal level, carry out photoetching and etching process and form the figure that movable electrode, movable mass, elastic beam and fixed electorde are drawn through-hole structure;
5) litho pattern foundation described rapid 4), draws through hole by described structure substrate being carried out to dry etching to obtain movable mass, elastic beam and two electrodes;
6) provide a cover plate substrate, at described cover plate substrate back, carry out photoetching and etching process is produced the cover plate cavity corresponding with described movable mass;
7) front of structure substrate in the cover plate substrate back in described step 6) and described step 5) is bonded together;
8) on the cover plate substrate of the deep etch technique by photoetching and silicon in described step 7), form electrode and draw through hole;
9) by routing mode, from described electrode, draw and through hole, draw fixed electorde and movable electrode.
2. the method for making of differential capacitance micro-acceleration sensor according to claim 1, is characterized in that: the material at the positive metal level depositing of described structure substrate in described step 4) is Au, Al, Cu or Ag.
3. the method for making of differential capacitance micro-acceleration sensor according to claim 1, is characterized in that: the bonding technology in described step 7) is wafer-level low-temperature vacuum bonding, and the bonding material of employing is glass paste, polymkeric substance or metal-to-metal adhesive.
4. the method for making of differential capacitance micro-acceleration sensor according to claim 1, it is characterized in that: described step 2), the on-chip electrode of structure is drawn through hole and the on-chip electrode of described step 5) cover plate and drawn through hole and align, for described fixed electorde and movable electrode are drawn.
5. the method for making of differential capacitance micro-acceleration sensor according to claim 1, is characterized in that: when the substrate in described step 1) is glass sheet, the material of the metal level depositing on described glass sheet in this step 1) is Au, Al, Cu or Ag; In described step 3), adopt anode linkage technique that the back side of substrate face and described structure substrate is bonded together.
6. the method for making of differential capacitance micro-acceleration sensor according to claim 1, is characterized in that, when the substrate in described step 1) is silicon chip, described step 1) also comprises:
1-1) provide a substrate, at the front of described substrate thermal oxide growth one deck monox;
1-2) at described step 1-1) front of substrate prepares Au layer, and on described Au layer, carry out photoetching and etching process is produced a pair of interdigitated fixed electorde;
Described step 2) also comprise:
2-1) provide a structure substrate, and at described structure substrate back thermal oxide growth one deck monox;
2-2) at described step 2-1) monox on carry out photoetching and etching process and produce for discharging preset cavity and the electrode of movable structure and draw through hole;
2-3) at described structure substrate back, make bonding contact ring.
7. the method for making of differential capacitance micro-acceleration sensor according to claim 6, is characterized in that: described step 2-3), the material of bonding contact ring is glass paste, polymkeric substance or metal-to-metal adhesive.
8. the method for making of differential capacitance micro-acceleration sensor according to claim 1, is characterized in that: described structure substrate is silicon chip or SOI substrate; Described cover plate substrate is silicon chip.
9. the method for making of differential capacitance micro-acceleration sensor according to claim 8, is characterized in that: when described structure substrate is SOI substrate, and described step 2) also comprise:
2-1) provide a structure substrate, at top layer silicon Film by Thermal Oxidation one deck monox of described structure substrate back;
2-2) on the silicon oxide layer of described structure substrate back, carry out photoetching and etching, output the corrosion window of described top layer silicon, then take monox as mask, the top layer silicon of described corrosion window is carried out to etching until reach buried regions silicon oxide layer, to form for discharging preset cavity and the electrode of movable structure, draw through hole;
2-3) utilize dry etching by described step 2-2) in the described buried regions monox that exposes of structure substrate back etch away.
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| CN103292800B (en) * | 2013-05-15 | 2016-02-03 | 北京航空航天大学 | A kind of one chip integrated optical gyroscope and manufacture method thereof |
| CN103472260B (en) * | 2013-08-15 | 2015-09-02 | 北京时代民芯科技有限公司 | A kind of MEMS pitches beam capacitive accelerometer and manufacture method thereof |
| CN105084302A (en) * | 2014-05-19 | 2015-11-25 | 无锡华润上华半导体有限公司 | Manufacturing method of MEMS mass block |
| CN104401930A (en) * | 2014-12-04 | 2015-03-11 | 中国科学院半导体研究所 | Wafer level packaging type MEMS (Micro Electro Mechanical System) device |
| CN105988019A (en) * | 2015-01-30 | 2016-10-05 | 北京大学 | Wafer level test method for structure parameters of silicon micro accelerometer |
| CN106908626B (en) * | 2015-12-23 | 2019-06-11 | 北京自动化控制设备研究所 | A kind of capacitance microaccelerator sensitive structure |
| CN105675921B (en) * | 2016-01-18 | 2018-10-26 | 广东合微集成电路技术有限公司 | A kind of acceleration transducer and preparation method thereof |
| CN106405152A (en) * | 2016-10-19 | 2017-02-15 | 北京大学深圳研究生院 | Micro accelerator and manufacturing method thereof |
| JP6816603B2 (en) * | 2017-03-27 | 2021-01-20 | セイコーエプソン株式会社 | Physical quantity sensors, electronics, and mobiles |
| CN108303567B (en) * | 2018-02-02 | 2020-04-24 | 扬州杰利半导体有限公司 | Preparation method of three-mass MEMS capacitance differential type triaxial accelerometer integrated by single chip |
| CN110040682B (en) * | 2019-04-19 | 2021-06-18 | 中国科学院上海微系统与信息技术研究所 | Preparation method of high-sensitivity acceleration sensor structure |
| CN110668394B (en) * | 2019-08-27 | 2022-08-12 | 华东光电集成器件研究所 | Preparation method of anti-interference overload-resistant MEMS accelerometer |
| CN110879303B (en) * | 2019-10-23 | 2022-01-04 | 杭州士兰微电子股份有限公司 | Inertial sensor and control method thereof |
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