CN107328449A - A kind of thermoelectric pile formula gas flow sensor and preparation method thereof - Google Patents
A kind of thermoelectric pile formula gas flow sensor and preparation method thereof Download PDFInfo
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- CN107328449A CN107328449A CN201710548160.3A CN201710548160A CN107328449A CN 107328449 A CN107328449 A CN 107328449A CN 201710548160 A CN201710548160 A CN 201710548160A CN 107328449 A CN107328449 A CN 107328449A
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- monocrystalline silicon
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
- G01F1/6888—Thermoelectric elements, e.g. thermocouples, thermopiles
Abstract
The present invention provides a kind of thermoelectric pile formula gas flow sensor and preparation method thereof, and structure includes：Substrate, with a groove, is opened in substrate top surface；First medium film, is covered in above groove, is connected with substrate, and surrounds with substrate a heat-insulated cavity jointly；Heating element heater, positioned at first medium film surface；At least two sensing elements, on first medium film, and are arranged at heating element heater both sides, including at least one set of monocrystalline silicon metal fever couple group, monocrystalline silicon metal fever couple group includes several monocrystalline silicon metal fever couples.The single silicon-chip one side manufacturing technology of the present invention is combined by such scheme, the golden thermocouple pair of Seebeck coefficient highest p type single crystal silicon is processed on common monocrystalline silicon piece, and isolate thermocouple pair and heating element heater with substrate by heat-insulated cavity, the heat dissipation of adding thermal resistance is at utmost reduced, the detection sensitivity of sensor is improved.In addition, inventive sensor size is small, cost is low, suitable for producing in enormous quantities.
Description
Technical field
The invention belongs to silicon micro mechanical sensor technical field, more particularly to a kind of thermoelectric pile formula gas flow sensor
And preparation method thereof.
Background technology
Gas flow is the call parameter of industrial processes, scientific research and various business accounting, the survey of gas flow
Amount occupies an important position in the industrial production.In the last few years, due to process industrial, energy meter, urban public utilities convection current
The demand sharp increase of measurement, wherein thermal flow rate sensor are easy to be miniaturized and extensive use due to simple in construction.As
The Typical Representative of thermal flow rate sensor, thermoelectric pile formula gas flow sensor mainly has some following advantage：Temperature is inputted
It can be exported as its energy, it is not necessary to which thermal signal is switched to electric signal by electric energy；Answered with self-produced come into force, ability when having temperature difference
Output voltage is had, so output voltage is without compensation and null offset；In addition, only needing voltmeter, simple operation during test.Cause
This, with the continuous progress of MEMS manufacturing technologies, thermoelectric pile formula gas flow sensor with its high-performance, low cost, be easy to letter
Number processing etc. advantage wait until extensive use in fields such as automotive electronics, Aero-Space, biochemical medicines.
The operation principle of thermoelectric pile formula gas flow sensor is to be based on Seebeck effect (Seebeck Effect), measurement
Because flow of fluid causes the asymmetrical variable quantity of heater two ends temperature, so that it is determined that rate of flow of fluid.Therefore, thermocouple is improved to plug
Seebeck coefficient and reduction device size are the development trends of thermoelectric pile formula gas flow sensor.
Limited at present by manufacture craft, many polysilicon-metal combinations low using Seebeck coefficient on non-soi wafer,
Performance is detected to improve sensor to brachium mode to quantity or increase thermocouple by increasing thermocouple；In addition, thermoelectric pile formula flow
Sensor is more on (100) silicon chip based on two-sided micromachined, and the units test sensitivity so made is low, and chip
Size is larger, and cost of manufacture is high, is unfavorable for mass manufacture.
Meanwhile, in order to reduce chip size, improve detection sensitivity, scientific worker have also been made numerous studies, but be difficult to
Take into account high sensitivity and miniaturization.
In order to reduce chip size, G.Kaltsas in 1999 et al. is used as thermocouple material with p-type polysilicon-aluminum metal, uses
Porous silicon as dielectric layer using one side micromachined mode manufacture gas flow sensor [Kaltsas G,
Nassiopoulou A.G.Novel C-MOS compatible monolithic silicon gas flow sensor
with porous silicon thermal isolation[J].Sensors and Actuators A:Physical,
1999,76(1):133-138.].Although this thermoelectric pile formula gas flow sensor realizes the making of single silicon-chip one side, reduction
Chip size, but the thermoelectric pile formula flow sensor for preparing of this technique has that following some is not enough：(1) list can not be realized
The making of crystal silicon-metal thermocouple arm, causes sensor detection sensitivity to be limited by Seebeck coefficient；(2) porous silicon have compared with
Big internal stress, occurs different degrees of crack performance for a long time in atmosphere, can influence the performance of sensor；(3) generate
The chemical reaction process of porous silicon is complicated, and shaping situation is difficult to accurate control, and this defect can be brought not to sensor yield rate
Profit influence；(4) use of this porous silicon technology has limitation, and no IC semiconductors foundry can run such spy
Different technique；(5) thermal conductivity of porous silicon will be far above air, cause developed sensor heat dissipation than larger.
In order to improve detection sensitivity, the D.Randjelovi ü of IHTM-IMTM companies in 2002 et al. use Seebeck coefficient
High p-type monocrystalline silicon-gold is used as thermocouple material development gas flow sensor [Randjelovic D, Kaltsas G, Lazic
Z,et al.Multipurpose thermal sensor based on Seebeck effect[C],Proc.23rd
International Conference on Microelectronics(MIEL 2002),2002,1:261-264.].First
In the 30 μm wide p type single crystal silicon thermocouple arm of N-type silicon substrate upper heavy doping boron formation；Then thermocouple pair is constituted with golden thermocouple arm；Finally
Monocrystalline silicon is thinned to form thin layer monocrystalline silicon+SiO2 insulation medium films by silicon chip back side wet etching.Although the device is one
Determine to improve the sensitivity of gas flow sensor in degree, but still suffer from that following some is not enough：(1) sensor adding thermal resistance
The deielectric-coating at place is that thin layer monocrystalline silicon+SiO2 is combined, and because monocrystalline silicon thermal conductivity coefficient is big, causes sensor heat dissipation high
And then the detection sensitivity of sensor is reduced to a certain extent；(2) silicon chip is thinned to thin layer monocrystalline silicon+SiO2 in back side wet etching
Deielectric-coating, etching time is difficult to control, if etching time is long to cause thermocouple to being corroded；(3) by (100) silicon chip wet method
Etching characteristic understands that medium membrane area and monocrystalline silicon backside mask open areas ratio very little, silicon wafer thickness are bigger, chip
Size is bigger, and cost is higher.
To sum up, Conventional thermoelectric heap formula gas flow sensor is difficult to take into account high sensitivity and miniaturization.Piotto in 2016
Et al. using p-type polysilicon-N-type polycrystalline silicon as thermocouple to develop a half-way house thermoelectric pile formula gas flow sense
Device [Massimo Piotto, Francesco Del Cesta, Paolo Bruschi, Integrated smart gas flow
sensor with 2.6mW total power consumption and 80dB dynamic range[J]
.Microelectronic Engineering,2016,159:159-163].The chip is made using single silicon-chip one side, chip
Size is greatly reduced.In addition, the Seebeck coefficient (the μ V/K of Seebeck coefficient about 200) of p-type polysilicon-N-type polycrystalline silicon thermocouple pair
Relative to the Seebeck coefficient (the μ V/K of Seebeck coefficient about 450) using monocrystalline silicon as thermocouple arm although far short of what is expected, relatively
To be improved much in p-type polysilicon-metal fever couple.Accordingly, with respect to previously reported thermoelectric pile formula gas flow sensor,
The sensor that Piotto et al. is developed in sensitivity also has external manufacture craft to be hoisted except obtaining very big progress.But,
Piotto et al. could not still solve to make p type single crystal silicon-metal fever by single silicon-chip single-sided process using common monocrystalline silicon piece
The technical barrier of couple.
Therefore, design it is a kind of can solve that heat dissipation in the prior art is high, size is big, cost is high, the low problem of performance
Thermoelectric pile formula gas flow sensor is necessary.
The content of the invention
The shortcoming of prior art in view of the above, it is an object of the invention to provide a kind of thermoelectric pile formula gas flow biography
Sensor and preparation method thereof, for solving, thermoelectric pile formula gas flow sensor heat dissipation in the prior art is high, size is big, cost
High, the low problem of performance.
In order to achieve the above objects and other related objects, the present invention provides a kind of thermoelectric pile formula gas flow sensor, bag
Include：
Substrate, with a groove, the groove is opened in the upper surface of the substrate；
First medium film, is covered in above the groove, and is connected with the substrate, the first medium film with it is described
Substrate surrounds a heat-insulated cavity jointly；
Heating element heater, positioned at the first medium film surface；And
At least two sensing elements, on the first medium film, and are arranged at the both sides of the heating element heater, described
Sensing element includes at least one set of monocrystalline silicon-metal fever couple group, and the monocrystalline silicon-metal fever couple group includes several monocrystalline
Silicon-metal thermocouple pair.
As a preferred embodiment of the present invention, the first medium film includes the groove profile that several run through its upper and lower surface
Structure, the trench structure is be arranged in parallel with the monocrystalline silicon-metal fever couple group and alternate intervals are arranged.
As a preferred embodiment of the present invention, the monocrystalline silicon-metal fever couple includes monocrystalline silicon thermocouple arm and metal
Thermocouple arm, the monocrystalline silicon thermocouple arm is located at the first medium film close to the surface of the groove side, the metal thermocouple
Arm includes vertical component effect and horizontal part, and the vertical component effect is connected through the first medium film with the monocrystalline silicon thermocouple arm, institute
Horizontal part is stated with the vertical component effect to be connected and positioned at surface of the first medium film away from the groove side.
As a preferred embodiment of the present invention, the heating element heater is located at the first medium film close to the groove one
The surface of side.
As a preferred embodiment of the present invention, the substrate is (111) monocrystalline silicon.
As a preferred embodiment of the present invention, the first medium film includes the TEOS passivation being sequentially stacked from bottom to top
Layer and silicon nitride layer, also include oxide layer between the first medium film and the substrate.
As a preferred embodiment of the present invention, the heating element heater edge<110>Crystal orientation is arranged, the monocrystalline silicon-metal
Thermocouple is to edge<211>Crystal orientation is arranged.
As a preferred embodiment of the present invention, in addition to second medium film, the second medium film is covered in the list
The upper surface of the first medium film of crystal silicon-metal fever couple group and its surrounding, for protecting the monocrystalline silicon-metal thermocouple
It is right.
As a preferred embodiment of the present invention, in addition to several lead pad, on the substrate, and it is arranged at
The two ends of the heating element heater and each sensing element.
As a preferred embodiment of the present invention, in addition to ambient resistance element, it is arranged on the substrate.
As a preferred embodiment of the present invention, the ambient resistance element, the heating element heater and the monocrystalline silicon-
Monocrystalline silicon thermocouple arm in metal fever couple is boron doped monocrystalline silicon.
The present invention also provides a kind of preparation method of thermoelectric pile formula gas flow sensor, and the preparation method is the present invention
The preparation method of the thermoelectric pile formula gas flow sensor of the offer, comprises the following steps：
1) substrate is provided, and in defining heating element heater area and at least two sensing element areas, institute on the substrate
Sensing element area is stated positioned at heating element heater area both sides, and including at least one monocrystalline silicon-metal fever couple group area, the list
Crystal silicon-metal fever couple group area includes several monocrystalline silicon-metal fever couple area；
2) substrate is etched to form first groove, for defining heating element heater and monocrystalline silicon-metal fever couple
In monocrystalline silicon thermocouple arm where position and thickness；
3) in first groove side wall formation side wall protective layer, and in being formed with described the first of the side wall protective layer
Deposition of sacrificial layer in groove；
4) in step 3) obtained by body structure surface deposition first medium membrane layers, and etch the first medium membrane material
The bed of material exposes the monocrystalline to exposing the corresponding substrate area of the heating element heater to form heating element heater connecting hole
The corresponding substrate area of monocrystalline silicon thermocouple arm of silicon-metal thermocouple centering is to form monocrystalline silicon thermocouple arm connecting hole；
5) in step 4) obtained by the surface deposited metal layer of structure and graphical to its, with formed the monocrystalline silicon-
Metal thermocouple arm in metal fever couple, the metal thermocouple arm includes vertical component effect and horizontal part, and the vertical component effect is through described
First medium membrane layers, the horizontal part is connected with the vertical component effect and positioned at the first medium membrane layers surface；
6) etch step 5) obtained structure to form second groove, the second groove be located at the adjacent monocrystalline silicon-
Between metal fever couple group area and/or the monocrystalline silicon-between metal fever couple group area and the substrate；
7) heat-insulated cavity is formed using second groove substrate described in window erodable section, to discharge the first medium
Film and the monocrystalline silicon thermocouple arm, wherein, the first medium film is connected with the substrate, and is enclosed jointly with the substrate
Into the heat-insulated cavity, the monocrystalline silicon thermocouple arm constitutes the monocrystalline silicon-metal fever couple, and shape with the metal thermocouple arm
Into sensing element.
Be used as a preferred embodiment of the present invention, step 1) and step 2) between, in addition to the heating element heater area with
And the sensing element area carries out boron doped step.
As a preferred embodiment of the present invention, carry out after the boron doping process, in addition to the structure after being adulterated to boron
The step of being annealed.
It is used as a preferred embodiment of the present invention, step 3) in, in the side wall formation side wall protective layer of the first groove
Concretely comprise the following steps：
3-1) in step 2) the obtained body structure surface deposited sidewalls protected material bed of material, the side-wall material protective layer include from
The TEOS layers and silicon nitride layer being sequentially depositing on down；
The side wall protected material bed of material on the substrate of the first groove bottom and its surrounding 3-2) is removed, with shape
Into the side wall protective layer positioned at first groove side wall.
Be used as a preferred embodiment of the present invention, step 5) and step 6) between, be also included in step 5) obtained by knot
The step of structure surface deposits second medium membrane layers, the second medium membrane layers are used to protect the sensing element.
It is used as a preferred embodiment of the present invention, step 6) in, forming the specific steps of the second groove includes：
6-1) etch the first medium membrane layers of the second groove region；
6-2) continue to etch desired depth along the second groove region, to form the second groove.
Be used as a preferred embodiment of the present invention, step 1) described in substrate be (111) monocrystalline silicon, step 7) employed in
Etchant solution be tetramethyl Dilute Ammonia Solution.
It is used as a preferred embodiment of the present invention, step 7) in, the first medium film of release includes several groove profiles
Structure, wherein, the trench structure is formed by the second groove, the trench structure and the monocrystalline silicon-metal fever couple
Group is be arranged in parallel and alternate intervals are arranged.
As described above, thermoelectric pile formula gas flow sensor of the present invention and preparation method thereof, has the advantages that：
1) present invention is by cleverly structure design and the single-chip one side manufacturing technology of innovation, in common (111) monocrystalline
Seebeck coefficient highest p type single crystal silicon-gold thermocouple pair is processed on silicon chip；
2) thermoelectric pile formula gas flow sensor of the invention passes through thermocouple pair and heating element heater immediately below it
Heat-insulated cavity isolate with substrate, at utmost reduce the heat dissipation of adding thermal resistance, substantially increase sensor detection spirit
Sensitivity；
3) whole flow sensor of the invention is all to be processed making, therefore chip from the same surface of monocrystalline silicon piece
Size is small, and cost is low, suitable for producing in enormous quantities.
Brief description of the drawings
Fig. 1 is shown as the global structure schematic diagram for the thermoelectric pile formula gas flow sensor that the present invention is provided.
Fig. 2 is shown as the thermoelectric pile formula gas flow sensor three-dimensional structure diagrammatic cross-section that the present invention is provided.
The structure that Fig. 3 to Figure 14 is shown as each step of preparation technology of the thermoelectric pile formula gas flow sensor of the present invention is shown
It is intended to：
Fig. 3 is shown as providing the structural representation of substrate in the gas flow sensor preparation process of the present invention；
Fig. 4 is shown as heating element heater and sensing element structure defined in the gas flow sensor preparation process of the present invention and shown
It is intended to；
Fig. 5 is shown as being formed the structural representation of first groove in the gas flow sensor preparation process of the present invention；
Fig. 6 is shown as the structural representation of the deposited sidewalls protected material bed of material in the gas flow sensor preparation process of the present invention
Figure；
Fig. 7 is shown as being formed the structural representation of side wall protective layer in the gas flow sensor preparation process of the present invention；
Fig. 8 is shown as being formed the structural representation of polysilicon sacrificial layer in the gas flow sensor preparation process of the present invention
Figure；
The structure that Fig. 9 is shown as being formed first medium membrane layers in the gas flow sensor preparation process of the present invention is shown
It is intended to；
Figure 10 is shown as being formed the structural representation of monocrystalline silicon connecting hole in the gas flow sensor preparation process of the present invention
Figure；
Figure 11 is shown as being formed the structural representation of metal thermocouple arm in the gas flow sensor preparation process of the present invention；
The structure that Figure 12 is shown as being formed second medium material layer in the gas flow sensor preparation process of the present invention is shown
It is intended to；
Figure 13 is shown as being formed the structural representation of second groove in the gas flow sensor preparation process of the present invention；
Figure 14 is shown as the structural representation of the heat-insulated cavity of corrosion release in the gas flow sensor preparation process of the present invention
Figure；
Figure 15 is shown as each process flow chart in the thermoelectric pile formula gas flow sensor preparation process of the present invention.
Component label instructions
1 substrate
11 grooves
12 boron ion injection regions
13 oxide layers
14 first grooves
141 side wall protective layers
1411 TEOS layers
1412 silicon nitride layers
142 polysilicon sacrificial layers
2 first medium films
21 trench structures
22 first medium membrane layers
221 silicon nitride layers
222 TEOS passivation layers
23 monocrystalline silicon connecting holes
3 heating element heaters
4 sensing elements
41 monocrystalline silicon-metal fever couple group
411 monocrystalline silicon-metal fever couple
4111 metal thermocouple arms
4112 monocrystalline silicon thermocouple arms
5 ambient resistance elements
6 lead pad
7 second medium films
71 second medium membrane layers
8 second grooves
S1~S7 steps
Embodiment
Illustrate embodiments of the present invention below by way of specific instantiation, those skilled in the art can be by this specification
Disclosed content understands other advantages and effect of the present invention easily.The present invention can also pass through specific realities different in addition
The mode of applying is embodied or practiced, the various details in this specification can also based on different viewpoints with application, without departing from
Various modifications or alterations are carried out under the spirit of the present invention.
Fig. 1 is referred to Figure 15.It should be noted that the diagram provided in the present embodiment only illustrates this in a schematic way
The basic conception of invention, though only display is with relevant component in the present invention rather than according to package count during actual implement in diagram
Mesh, shape and size are drawn, and form, quantity and the ratio of each component can be a kind of random change during its actual implementation, and its
Assembly layout form may also be increasingly complex.
As shown in Figure 1, Figure 2 and shown in Figure 14, the present invention provides a kind of thermoelectric pile formula gas flow sensor, including：
Substrate 1, with a groove 11, the groove 11 is opened in the upper surface of the substrate 1；
First medium film 2, is covered in the top of groove 11, and is connected with the substrate 1, the first medium film 2
A heat-insulated cavity is surrounded jointly with the substrate 1；
Heating element heater 3, positioned at the surface of first medium film 2；And
At least two sensing elements 4, on the first medium film 2, and are arranged at the both sides of the heating element heater 3,
The sensing element includes at least one set of monocrystalline silicon-metal fever couple group 41, if the monocrystalline silicon-metal fever couple group 41 includes
Dry monocrystalline silicon-metal fever couple 411.
Specifically, in the present embodiment, the heating element heater 3 can be adding thermal resistance, the sensing element 4 is located at described
The position of the both sides of heating element heater 3, i.e. upstream and downstream, separately constitutes the independent thermoelectric pile detection circuit in upstream and downstream two.Wherein,
The monocrystalline silicon-metal fever couple group 41 can for one group or two or more sets, depending on actual demand, when monocrystalline silicon-gold
Belong to thermocouple to when group 41 is two or more sets, the first connection of the monocrystalline silicon-metal fever couple group 41 constitutes complete detection line
Road.Further, the monocrystalline silicon-metal fever couple group 41 can comprising any monocrystalline silicon-metal fever couple 411, such as 2~
100, depending on actual demand, it is not particularly limited herein, selection is 7 in the present embodiment.
Specifically, 1.3 μm of 518 μ m of size, 350 μ m of the first medium film 2, and the heat-insulated cavity constituted
Depth is 40~60 μm, and preferably 50 μm, the monocrystalline silicon-metal fever couple is constituted using p type single crystal silicon-gold metal material,
The independent thermoelectric pile in upstream and downstream two is by 21 pairs of thermocouples to constituting, and wherein thermocouple is 100~180 μm to length, is preferably
144 μm, width is 1~5 μm, and preferably 3 μm, thickness is 0.1~0.8 μm, preferably 0.3 μm, the overall length of the heating element heater
Spend for 300~380 μm, preferably 340 μm, width is 8~12 μm, and preferably 10 μm, its thickness is 0.1~0.5 μm, is preferably
0.3μm。
In addition, the setting of the heat-insulated cavity of the thermoelectric pile formula gas flow sensor of the application make the heating element heater and
The sensing element is completely vacantly with the substrate, and the silicon body for reducing the application radiates, in the present embodiment, the heating unit
Part is adding thermal resistance, and the sensing element includes p type single crystal silicon-gold metal fever couple.
As an example, the first medium film 2 includes the trench structure 21 that several run through its upper and lower surface, the groove profile
Structure 21 is be arranged in parallel with the monocrystalline silicon-metal fever couple group 41 and alternate intervals are arranged.
Specifically, the trench structure 21 makes between the adjacent monocrystalline silicon-metal fever couple group 41 and the monocrystalline
Silicon-metal thermocouple between group 41 and the substrate 1 to being physically separated from, that is to say, that each monocrystalline silicon-metal fever couple group 41
The corresponding first medium film 2 is spaced apart from each other, and sets the first of the monocrystalline silicon-metal fever couple group 41 to be situated between
Plasma membrane and to be not provided with thermocouple be also separated from each other to the first medium film part of group, is also achieved that the monocrystalline silicon-metal
Thermocouple is to 41 physical isolations with substrate, so as to prevent heat from being transmitted between deielectric-coating, that is to say, that make the sensing
Each monocrystalline silicon-thermocouple of element 4 by air to being isolated completely between group 41, so that the silicon body radiating of the application is reduced,
Improve the performance of sensor.In addition, the trench structure 21 can also be arranged at the heating element heater and the sensing element
Between the first medium film on so that the two is isolated by air, reduce thermal losses.
As an example, the monocrystalline silicon-metal fever couple 411 includes monocrystalline silicon thermocouple arm 4112 and metal thermocouple arm
4111, the monocrystalline silicon thermocouple arm 4112 is located at the first medium film 2 close to the surface of the side of groove 11, the metal
Thermocouple arm 4111 includes vertical component effect and horizontal part, and the vertical component effect is through the first medium film 2 and the monocrystalline silicon thermocouple arm
4111 are connected, and the horizontal part is connected with the vertical component effect and positioned at the first medium film 2 away from the groove side
Surface.
As an example, the heating element heater 3 is located at surface of the first medium film 2 close to the side of groove 11.
Specifically, in the present embodiment, it is described in the heating element heater 3 and the monocrystalline silicon-metal fever couple 411
Monocrystalline silicon thermocouple arm 4112 is located at the same side of the first medium film 2, and the metal thermocouple arm 4111 is located at and the two phase
To the first medium film 2 opposite side, the heating element heater 3 and the monocrystalline silicon thermocouple arm 4112 are located at described first and are situated between
The homonymy of plasma membrane 2, and positioned at the side close to the groove 11, advantageously reduce thermal losses, be further ensured that thermoelectric pile formula gas
The sensitivity of body flow sensor, improves device performance.In addition, the arm of monocrystalline silicon thermocouple described in the present embodiment can be inhomogeneity
The monocrystalline silicon of type doping, the metal thermocouple arm can also be the various metal materials such as Pt, Ni, Au, Al, Cu, do not do have herein
Body is limited.
As an example, the substrate 1 is (111) monocrystalline silicon.
Specifically, the substrate 1 can be monocrystalline silicon, polysilicon, metal liner is low, organic lining is low, PCB serves as a contrast low various linings
Low material, can be further the list of (111) crystal face of N-type (or p-type) using (111) monocrystalline substrate in the present embodiment
The silicon chip of face (or two-sided) polishing, it can improve many defects of traditional silicon chip (such as (100) silicon chip), such as by (100) silicon
Piece wet etching characteristic understands that medium membrane area and monocrystalline silicon backside mask open areas ratio very little, silicon wafer thickness are got over
Greatly, chip size is bigger, and cost is higher, and the girder structure where the heating element heater and the temperature-sensitive element needs edge
(110) the certain angle of crystal orientation deflection could realize that girder construction wet etching discharges, fixed which results in sensor subsequent installation
Bit comparison is difficult.
As an example, the edge of heating element heater 3<110>Crystal orientation is arranged, the monocrystalline silicon-edge of metal fever couple 411<211>
Crystal orientation is arranged.
Specifically, the present invention the first medium film unit design, make heating element heater 3 along<110>Crystal orientation is arranged,
Make the monocrystalline silicon-edge of metal fever couple 411<211>Crystal orientation is arranged, so as to ensure that the device architecture of the present invention is adapted to
The diminution of size, it is ensured that the performance of sensor.In addition, in the present embodiment, preferably described sensing element 4 is in the heating element heater
3 both sides are uniformly and symmetrically distributed, it is ensured that being uniformly distributed for the thermal field of sensor in use, further increase gas stream
The detection performance of quantity sensor.
As an example, the first medium film 2 includes the TEOS passivation layers 222 and silicon nitride layer being sequentially stacked from bottom to top
221, oxide layer is also included between the first medium film and the substrate.
As an example, also including second medium film 7, the second medium film 7 is covered in the monocrystalline silicon-metal fever couple
The upper surface of group 41 and its surrounding first medium film 2, for protecting the monocrystalline silicon-metal fever couple.
Specifically, the first medium film includes the TEOS passivation layers 222 of low stress and the silicon nitride layer 221 of low stress,
Wherein, the TEOS passivation layers are low stress TEOS (tetraethyl orthosilicate, Si (OC2H5)4) passivation layer.In addition, when to the application's
Define heating element heater and sensing element area substrate annealed after, in addition to formed the first medium film with it is described
Oxide layer 13 between substrate, in other embodiments, the formation process of the oxide layer are not limited to annealing process, may be used also
Think the techniques such as deposition.
Specifically, in the present embodiment, in addition to it is arranged on the second medium film 7 of the periphery of sensing element 4, described second
Deielectric-coating 7 can be silicon dioxide layer of protection or silicon nitride film, silica and silicon nitride composite membrane, organic film
Etc. the various thin-film materials with insulation characterisitic, the purpose is to common by the part monocrystalline silicon-metal fever with first medium film
Couple is coated, to protect all metallic resistance structures not by ectocine, to increase the long-time stability and reliability of device.
As an example, also including several lead pad 6, on the substrate 1, and the heating element heater 3 is arranged at
And the two ends of each sensing element 4.
As an example, also including ambient resistance element 5, it is arranged on the substrate 1.
As an example, the ambient resistance element 5, the heating element heater 3 and the monocrystalline silicon-metal fever couple 411
In monocrystalline silicon thermocouple arm 4112 be boron doped monocrystalline silicon.
Specifically, present invention additionally comprises ambient resistance element 5, the temperature of environment can directly utilize ambient resistance member
The direct measurement of part 5 and compensation, so as to eliminate influence of the gas temperature fluctuation to measurement result, so as to improve flow detection
Precision.Preferably, the ambient resistance element edge<110>Crystal orientation is arranged.In addition, the ambient resistance element 5, the heating unit
Monocrystalline silicon thermocouple arm 4112 in part 3 and the monocrystalline silicon-metal fever couple 411 is preferably dense boron doping, further to carry
High device performance.
As shown in Fig. 1~15, the present invention also provides a kind of preparation method of thermoelectric pile formula gas flow sensor, the system
Preparation Method is the preparation method of the thermoelectric pile formula gas flow sensor of offer of the present invention, is comprised the following steps：
As shown in the S1 in Fig. 3~4 and Figure 15,1) substrate 1 is provided, and in defining heating element heater on the substrate 1
Area and at least two sensing element areas, the sensing element area are located at heating element heater area both sides, and including at least one
Monocrystalline silicon-metal fever couple group area, the monocrystalline silicon-metal fever couple group area includes several monocrystalline silicon-metal fever couple area；
Specifically, the heating element heater area is used to form heating element heater 3, the sensing element area is used to form sensing element
4, the sensing element 4 is located at the position of the both sides, i.e. upstream and downstream of the heating element heater 3, separately constitutes the independence of upstream and downstream two
Thermoelectric pile detection circuit.The monocrystalline silicon-metal fever couple group 41 can for one group or two or more sets, according to actual demand
Depending on, when monocrystalline silicon-metal fever couple group 41 is two or more sets, the first connection of the monocrystalline silicon-metal fever couple group 41,
Constitute the detection circuit completed.Further, the monocrystalline silicon-metal fever couple group 41 can include any monocrystalline silicon-metal
Thermocouple such as 2~100, depending on actual demand, is not particularly limited herein to 411, and selection is 7 in the present embodiment.
As an example, the substrate 1 is (111) monocrystalline silicon.
Specifically, the thickness of the substrate 1 can be 350~500 μm, preferably 430 μm, its axle is cut to 0 ± (0.01 partially
~0.5) °, preferably 0 ± 0.1 °.The substrate 1 can be monocrystalline silicon, polysilicon, metal liner is low, organic lining is low, PCB linings are low
Can be further (111) of N-type (or p-type) using (111) monocrystalline substrate in the present embodiment etc. the various low materials of lining
The silicon chip of one side (or two-sided) polishing of crystal face, it can improve many defects of traditional silicon chip (such as (100) silicon chip), such as by
(100) silicon wafer wet etching characteristic is understood, medium membrane area and monocrystalline silicon backside mask open areas ratio very little, silicon chip
Thickness is bigger, and chip size is bigger, and cost is higher, and the girder structure where the heating element heater and the temperature-sensitive element is needed
It could realize that girder construction wet etching discharges along the certain angle of (110) crystal orientation deflection, subsequently pacify which results in sensor
Set bit comparison difficult.
As an example, step 1) after, in addition to the heating element heater area and sensing element area progress boron are mixed
Miscellaneous step.
As an example, carry out after the boron doping process, in addition to structure after being adulterated to boron is the step of anneal.
Specifically, the method for defining the heating element heater area and the sensing element area is：In the surface heat of substrate 1
The certain thickness oxide layer of oxygen simultaneously forms one layer of photoresist layer, in the formation area to be defined in the oxide layer and photoresist layer
The opening in domain, ion implanting is carried out by the opening, in the present embodiment preferably dense boron doping, and implantation dosage is 5e15cm2
~15e15cm2, preferably 9e15cm2, Implantation Energy is 20~70Kev, preferably 50Kev, is filled with the boron ion note of boron ion
It is subsequently to form the region of heating element heater, monocrystalline silicon-metal thermocouple arm to enter region 12, furthermore it is also possible to including follow-up
Ambient resistance element area.
Further, the step of the present embodiment also includes annealing to the structure for the boron that adulterates, annealing time is about 1.5~
Superficial growth layer of oxide layer 13 after 2.5h, preferably 2h, annealing, the thickness of the oxide layer is 4000~6000 angstroms, this reality
Apply in example, the thickness of the oxide layer is 5000 angstroms, is further ensured that the stability of device, as shown in Figure 4.
As shown in the S2 in Fig. 5 and Figure 15, step 2 is carried out), the substrate is etched to form first groove 14, for fixed
Justice goes out position and the height of heating element heater 3 and monocrystalline silicon-metal fever couple 411；
Specifically, the effect of the first groove 14 is to be used to limit heating element heater 3 and monocrystalline silicon-metal fever couple
411, by taking the monocrystalline silicon-metal fever couple 411 as an example, the first groove 14 is arranged at the monocrystalline subsequently to be formed
Silicon-metal thermocouple is used as expendable material, in follow-up etching process, the filler in the first groove to 411 both sides
Can be corroded, then remain the part of its both sides, namely monocrystalline silicon-metal fever couple 411 part.Further, its depth
For limiting the degree in successive substrates corrosion process, and then limit the thickness of monocrystalline silicon-metal fever couple 411.
As shown in the S3 in Fig. 6~8 and Figure 15, step 3 is carried out), in the side wall formation side wall protection of first groove 14
Layer 141, and in deposition of sacrificial layer 142 in the first groove 14 for be formed with the side wall protective layer；
As an example, step 3) in, in the specific steps of the side wall formation side wall protective layer 141 of the first groove 14
For：
3-1) in step 2) the obtained body structure surface deposited sidewalls protected material bed of material, the side-wall material protective layer include from
The TEOS layers 1411 and silicon nitride layer 1412 being sequentially depositing on down；
3-2) remove the side wall protected material bed of material on the substrate 1 of the bottom of first groove 14 and its surrounding
1411st, 1412, to form the side wall protective layer 141 positioned at the side wall of first groove 14.
Specifically, the sacrifice layer 142 includes but is not limited to polysilicon layer, its depositing operation can include but is not limited to oxygen
Change, low-pressure chemical vapor deposition (LPCVD), plasma reinforced chemical vapour deposition (PECVD) etc., the side wall protective layer 141
And the sacrifice layer 142 is used to be corroded in the step of successive substrates are corroded, its play the protection heating element heater 3 with
And the effect of monocrystalline silicon-metal fever couple 411, further, the thickness of the silicon nitride layer 1411 is 1000~3000 angstroms, described
The thickness of TEOS layers 1411 is 1000~3000 angstroms, in the present embodiment, and the thickness of the silicon nitride layer 1412 is 2000 angstroms, described
The thickness of TEOS layers 1411 is 2000 angstroms.
As shown in the S4 in Fig. 9~10 and Figure 15, carry out step 4), in step 3) obtained by body structure surface deposition first
Medium membrane layers 22, and the first medium membrane layers 22 are etched to exposing the corresponding substrate area of the heating element heater
To form heating element heater connecting hole, and expose the corresponding substrate of monocrystalline silicon thermocouple arm in the monocrystalline silicon-metal fever couple
Region is to form monocrystalline silicon thermocouple arm connecting hole 23；
Specifically, the first medium membrane layers 22 are used for as support membrane, it includes what is be sequentially depositing from bottom to top
TEOS layers and silicon nitride layer, wherein, described TEOS layers thickness is 1000~3000 angstroms, and the thickness of the silicon nitride layer is
7000~9000 angstroms, in the present embodiment, described TEOS layers thickness is 2000 angstroms, and the thickness of the silicon nitride layer is 8000
Angstrom, in addition, the purpose of the step also resides in the connecting hole 23 for preparing metal thermocouple arm, wherein, the connection of the metal thermocouple arm
The depth in hole 23 is 1.2~2.5 μm, is in the present embodiment 1.7 μm.In addition, also include formed heating element heater connecting hole and
The step of ambient resistance element connecting hole, for heating element heater and ambient resistance element to be drawn to realize electrical connection.
In addition, after the substrate for defining heating element heater and sensing element area to the application is annealed, in addition to
The oxide layer 13 formed between the first medium film and the substrate, the thickness of the oxide layer is 4000~6000 angstroms,
In the present embodiment, the thickness of the oxide layer is 5000 angstroms.In other embodiments, the formation process of the oxide layer not office
Annealing process is limited to, can also be the techniques such as deposition.
As shown in the S5 in Figure 11~12 and Figure 15, carry out step 5), in step 4) obtained by structure surface deposition
Metal level is simultaneously graphical to its, to form the metal thermocouple arm 4111 in the monocrystalline silicon-metal fever couple, the metal thermocouple
Arm 4111 includes vertical component effect and horizontal part, and the vertical component effect runs through the first medium membrane layers 22, the horizontal part and institute
Vertical component effect is stated to be connected and positioned at the surface of first medium membrane layers 22；
Specifically, depositing the metal level includes depositing one layer Cr layers first, layer of metal is deposited on described Cr layers
The step of material (such as Au), wherein, Cr layers of thickness is that 100~500 angstroms, Au layers of thickness is 3000~8000 angstroms, is preferably
5000 angstroms.In addition, the patterning process includes but is not limited to ion beam (Ionbeam) dry etching, the metal level is formed
Technique includes but is not limited to sputtering method.
As an example, step 5) and step 6) between, be also included in step 5) obtained by body structure surface deposition second be situated between
The step of film material layer 71, the second medium membrane layers 71 are used to protect the sensing element 4.
Specifically, the second medium membrane layers 71 can be silicon dioxide layer of protection or silicon nitride film, two
The various thin-film materials with insulation characterisitic such as silica and silicon nitride composite membrane, organic film, the purpose is to first medium
Film is common to coat the part monocrystalline silicon-metal fever couple, to protect all metallic resistance structures not by ectocine, to increase
Plus the long-time stability and reliability of device, its thickness is 1000~5000 angstroms, preferably 3000 angstroms.In addition, described first is situated between
The formation process of film material layer 22 and the second medium membrane layers 71 can include but is not limited to oxidation, low pressure chemical
It is vapor-deposited (LPCVD), the coating of plasma reinforced chemical vapour deposition (PECVD), sol gel process, organic material solidifies work
Skill etc..
Specifically, the step of forming lead pad 6 in the step is additionally included in, when etching the metal thermocouple arm
Together etching is formed, further, after the second medium membrane layers are formed, in addition to is removed in the lead pad 6
The step of material layer, such as it can fall draw using BOE (Buffered Oxide Etch, buffered oxide etch liquid) solution corrosion
SiO above wire bonding disk area2Passivation layer.
As shown in the S6 in Figure 13 and Figure 15, carry out step 6), etch step 5) obtained by structure with formed have it is pre-
If the second groove 8 of depth, the second groove 8 is located between the adjacent monocrystalline silicon-metal fever couple group area and/or described
Monocrystalline silicon-between metal fever couple group area and the substrate；
As an example, step 7) in, the first medium film 2 of release includes several trench structures 21, the groove profile
Structure is formed by the second groove 8, and the trench structure 21 be arranged in parallel and replaced with the monocrystalline silicon-metal fever couple group
It is intervally arranged.
Specifically, the second groove 8 is used as the window of follow-up progress substrate etching, and also further define described
The depth of the groove 11 in substrate 1, namely the heat-insulated cavity depth, meanwhile, the second groove 8 is also served as subsequently
Form the groove of the trench structure 21, its particular location is between the adjacent monocrystalline silicon-metal fever couple group area or institute
State monocrystalline silicon-between metal fever couple group area and the substrate, i.e., the side in described sensing element area, can also be located at simultaneously with
Upper several positions, depending on actual demand, its shape of cross section be preferably for the larger square bar of length-width ratio, its long side with it is described
Monocrystalline silicon-metal fever couple is in the same direction.
As an example, step 6) in, forming the specific steps of the second groove 8 includes：
6-1) etch the first medium membrane layers 22 of the region of second groove 8；
6-2) continue to etch desired depth along the second groove region, to form the second groove 8.
Specifically, step 6-1) in etching can use reactive ion etching (RIE), wherein, step 6-1) and can be with
Form the trench structure 21 being located on the first medium film, step 6-2) in etching can be using deep pasc reaction ion
Etch (Deep-RIE), it is of course also possible to use other etching technics, such as inductive reactive ion etching (ICP), ion beam
Etch the various lithographic techniques such as (IonBeam), wet etching, focused-ion-beam lithography (FIB), laser scanning etching.At other
In embodiment, the groove with predetermined depth once can also etch to be formed.Wherein, by step 6-2) etching it is just fixed
The depth of the depth of the groove in justice substrate, i.e., described second depth, namely the heat-insulated cavity, can be 40~60
μm, in the present embodiment, preferably 50 μm.Here, described " the second groove region " refers to ultimately form described
The region of first medium membrane layers and substrate corresponding to the position of second groove during second groove.
In addition, when in step 5) obtained by body structure surface deposition second medium membrane layers 71 when, step 4-1) quarter
Second medium membrane layers have also been etched away while etching eating away first medium membrane layers.
As shown in the S7 in Figure 14 and Figure 15, step 7 is carried out), it is to be served as a contrast described in window erodable section with the second groove 8
Bottom forms heat-insulated cavity, to discharge the first medium film 2 and the monocrystalline silicon thermocouple arm 4112, wherein, the first medium
Film 2 is connected with the substrate 1, and surrounds the heat-insulated cavity jointly with the substrate 1, the monocrystalline silicon thermocouple arm 4112 with
The metal thermocouple arm 4111 constitutes the monocrystalline silicon-metal fever couple 411, and forms sensing element 4.
As an example, step 1) described in substrate be (111) monocrystalline silicon, step 7) employed in etchant solution be tetramethyl
Base Dilute Ammonia Solution.
Specifically, in other embodiments, MEMS bulk silicon etching technologies can also be potassium hydroxide (KOH) solution corrosion,
The various silicon materials corrosion technologies such as xenon fluoride (XeF).
In addition, after the above step is finished, in addition to laser scribing, the step of to obtain required device architecture.
In summary, the present invention provides a kind of thermoelectric pile formula gas flow sensor and preparation method thereof, including：Substrate,
With a groove, the groove is opened in the upper surface of the substrate；First medium film, is covered in above the groove, and with
The substrate is connected, and the first medium film surrounds a heat-insulated cavity jointly with the substrate；Heating element heater, positioned at described
First medium film surface；And at least two sensing elements, on the first medium film, and it is arranged at the heating element heater
Both sides, the sensing element includes at least one set of monocrystalline silicon-metal fever couple group, the monocrystalline silicon-metal fever couple group bag
Include several monocrystalline silicon-metal fever couple.By such scheme, the present invention passes through cleverly structure design and the single-chip of innovation
One side manufacturing technology, Seebeck coefficient highest p type single crystal silicon-gold thermocouple pair is processed on common (111) monocrystalline silicon piece；This
The thermoelectric pile formula gas flow sensor of invention by thermocouple pair and heating element heater by the heat-insulated cavity immediately below it with
Substrate is isolated, and is at utmost reduced the heat dissipation of adding thermal resistance, is substantially increased the detection sensitivity of sensor；The present invention's
Whole flow sensor is all to be processed making from the same surface of monocrystalline silicon piece, therefore chip size is small, and cost is low, is suitable to
Produce in enormous quantities.So, the present invention effectively overcomes various shortcoming of the prior art and has high industrial utilization.
The above-described embodiments merely illustrate the principles and effects of the present invention, not for the limitation present invention.It is any ripe
Know the personage of this technology all can carry out modifications and changes under the spirit and scope without prejudice to the present invention to above-described embodiment.Cause
This, those of ordinary skill in the art is complete without departing from disclosed spirit and institute under technological thought such as
Into all equivalent modifications or change, should by the present invention claim be covered.
Claims (19)
1. a kind of thermoelectric pile formula gas flow sensor, it is characterised in that including：
Substrate, with a groove, the groove is opened in the upper surface of the substrate；
First medium film, is covered in above the groove, and is connected with the substrate, the first medium film and the substrate
A heat-insulated cavity is surrounded jointly；
Heating element heater, positioned at the first medium film surface；And
At least two sensing elements, on the first medium film, and are arranged at the both sides of the heating element heater, the sensing
Element includes at least one set of monocrystalline silicon-metal fever couple group, the monocrystalline silicon-metal fever couple group include several monocrystalline silicon-
Metal fever couple.
2. thermoelectric pile formula gas flow sensor according to claim 1, it is characterised in that the first medium film includes
Several run through the trench structure of its upper and lower surface, and the trench structure be arranged in parallel with the monocrystalline silicon-metal fever couple group
And alternate intervals are arranged.
3. thermoelectric pile formula gas flow sensor according to claim 1, it is characterised in that the monocrystalline silicon-metal fever
Couple includes monocrystalline silicon thermocouple arm and metal thermocouple arm, and the monocrystalline silicon thermocouple arm is located at the first medium film close to described recessed
The surface of groove side, the metal thermocouple arm include vertical component effect and horizontal part, the vertical component effect through the first medium film with
The monocrystalline silicon thermocouple arm is connected, and the horizontal part is connected with the vertical component effect and positioned at the first medium film away from institute
State the surface of groove side.
4. thermoelectric pile formula gas flow sensor according to claim 3, it is characterised in that the heating element heater is located at institute
State surface of the first medium film close to the groove side.
5. thermoelectric pile formula gas flow sensor according to claim 1, it is characterised in that the substrate is that (111) are single
Crystal silicon.
6. thermoelectric pile formula gas flow sensor according to claim 1, it is characterised in that the first medium film includes
The TEOS passivation layers and silicon nitride being sequentially stacked from bottom to top, also include oxidation between the first medium film and the substrate
Layer.
7. thermoelectric pile formula gas flow sensor according to claim 1, it is characterised in that the heating element heater edge<110
>Crystal orientation is arranged, the monocrystalline silicon-metal fever couple edge<211>Crystal orientation is arranged.
8. thermoelectric pile formula gas flow sensor according to claim 1, it is characterised in that also including second medium film,
The second medium film is covered in the upper surface of the first medium film of the monocrystalline silicon-metal fever couple group and its surrounding,
For protecting the monocrystalline silicon-metal fever couple.
9. thermoelectric pile formula gas flow sensor according to claim 1, it is characterised in that also welded including several leads
Disk, on the substrate, and is arranged at the two ends of the heating element heater and each sensing element.
10. according to thermoelectric pile formula gas flow sensor according to any one of claims 1 to 9, it is characterised in that also include
Ambient resistance element, is arranged on the substrate.
11. thermoelectric pile formula gas flow sensor according to claim 10, it is characterised in that the ambient resistance member
Monocrystalline silicon thermocouple arm in part, the heating element heater and the monocrystalline silicon-metal fever couple is boron doped monocrystalline silicon.
12. a kind of preparation method of thermoelectric pile formula gas flow sensor, it is characterised in that comprise the following steps：
1) substrate is provided, and in defining heating element heater area and at least two sensing element areas, the sense on the substrate
Survey element region and be located at heating element heater area both sides, and including at least one monocrystalline silicon-metal fever couple group area, the monocrystalline
Silicon-metal thermocouple includes several monocrystalline silicon-metal fever couple area to group area；
2) substrate is etched to form first groove, for defining in heating element heater and monocrystalline silicon-metal fever couple
Position and thickness where monocrystalline silicon thermocouple arm；
3) in first groove side wall formation side wall protective layer, and in the first groove for being formed with the side wall protective layer
Interior deposition of sacrificial layer；
4) in step 3) obtained by body structure surface deposition first medium membrane layers, and etch the first medium membrane layers
To the corresponding substrate area of the heating element heater is exposed to form heating element heater connecting hole, and expose the monocrystalline silicon-gold
Belong to the corresponding substrate area of monocrystalline silicon thermocouple arm of thermocouple centering to form monocrystalline silicon thermocouple arm connecting hole；
5) in step 4) obtained by the surface deposited metal layer of structure and graphical to its, to form the monocrystalline silicon-metal
The metal thermocouple arm of thermocouple centering, the metal thermocouple arm includes vertical component effect and horizontal part, and the vertical component effect runs through described first
Medium membrane layers, the horizontal part is connected with the vertical component effect and positioned at the first medium membrane layers surface；
6) etch step 5) obtained structure is to form second groove, and the second groove is located at the adjacent monocrystalline silicon-metal
Thermocouple between group area and/or the monocrystalline silicon-between metal fever couple group area and the substrate；
7) heat-insulated cavity is formed using second groove substrate described in window erodable section, with discharge the first medium film and
The monocrystalline silicon thermocouple arm, wherein, the first medium film is connected with the substrate, and surrounds jointly with the substrate described
Heat-insulated cavity, the monocrystalline silicon thermocouple arm constitutes the monocrystalline silicon-metal fever couple with the metal thermocouple arm, and forms sensing
Element.
13. the preparation method of thermoelectric pile formula gas flow sensor according to claim 12, it is characterised in that step 1)
With step 2) between, in addition to boron doped step is carried out to the heating element heater area and the sensing element area.
14. the preparation method of thermoelectric pile formula gas flow sensor according to claim 13, it is characterised in that carry out institute
State after boron doping process, in addition to the structure after being adulterated to boron is the step of anneal.
15. the preparation method of thermoelectric pile formula gas flow sensor according to claim 12, it is characterised in that step 3)
In, form concretely comprising the following steps for side wall protective layer in the side wall of the first groove：
3-1) in step 2) the obtained body structure surface deposited sidewalls protected material bed of material, the side-wall material protective layer includes from lower
On the TEOS layers and silicon nitride layer that are sequentially depositing；
The side wall protected material bed of material on the substrate of the first groove bottom and its surrounding 3-2) is removed, to form position
In the side wall protective layer of first groove side wall.
16. the preparation method of thermoelectric pile formula gas flow sensor according to claim 12, it is characterised in that step 5)
With step 6) between, be also included in step 5) obtained by body structure surface deposition second medium membrane layers the step of, described the
Second medium membrane layers are used to protect the sensing element.
17. the preparation method of thermoelectric pile formula gas flow sensor according to claim 12, it is characterised in that step 6)
In, forming the specific steps of the second groove includes：
6-1) etch the first medium membrane layers of the second groove region；
6-2) continue to etch desired depth along the second groove region, to form the second groove.
18. the preparation method of thermoelectric pile formula gas flow sensor according to claim 12, it is characterised in that step 1)
Described in substrate be (111) monocrystalline silicon, step 7) employed in etchant solution be tetramethyl Dilute Ammonia Solution.
19. the preparation method of the thermoelectric pile formula gas flow sensor according to any one of claim 12~18, it is special
Levy and be, step 7) in, the first medium film of release includes several trench structures, wherein, the trench structure is by institute
State second groove to be formed, the trench structure is be arranged in parallel with the monocrystalline silicon-metal fever couple group and alternate intervals are arranged.
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| CN113049053A (en) * | 2021-03-15 | 2021-06-29 | 青岛芯笙微纳电子科技有限公司 | High-performance MEMS flow sensor and preparation method thereof |
| CN113175963A (en) * | 2021-04-27 | 2021-07-27 | 华东师范大学 | MEMS flow sensor and preparation method thereof |
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| CN107328449B (en) | 2019-08-30 |
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