CN106969874A - Differential pressure sensing arrangement of power sensitive film thickness controllable precise and preparation method thereof - Google Patents
Differential pressure sensing arrangement of power sensitive film thickness controllable precise and preparation method thereof Download PDFInfo
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- CN106969874A CN106969874A CN201610023873.3A CN201610023873A CN106969874A CN 106969874 A CN106969874 A CN 106969874A CN 201610023873 A CN201610023873 A CN 201610023873A CN 106969874 A CN106969874 A CN 106969874A
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L13/00—Devices or apparatus for measuring differences of two or more fluid pressure values
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Abstract
The present invention provides a kind of differential pressure sensing arrangement of power sensitive film thickness controllable precise and preparation method thereof, including：Monocrystalline silicon substrate；Pressure reference cavity；Polysilicon power sensitive thin film on pressure reference cavity, the monocrystalline silicon stress concentration structure positioned at polysilicon power sensitive thin film upper surface, the piezo-resistance positioned at monocrystalline silicon stress concentration structure upper surface；Via, is communicated through the back side of monocrystalline silicon substrate with pressure reference cavity.The present invention is made using thin-film technique under body silicon, and polysilicon power sensitive thin film is deposited over the monocrystalline silicon layer lower surface after silicon bulk fabrication and film thickness controllable precise, one layer of silicon oxide layer is clipped between monocrystalline silicon layer and polysilicon power sensitive thin film；Monocrystalline silicon layer formation monocrystalline silicon stress concentration structure is etched by dry method self-stopping technology, silicon oxide layer is finally removed and exposes polysilicon power sensitive thin film.The present invention substantially increases the uniformity and high finished product rate of high sensitivity pressure sensor sensitive thin film structure processing, is adapted to produce in enormous quantities.
Description
Technical field
The present invention relates to silicon micro mechanical technical field, more particularly to a kind of differential pressure sensing arrangement of power sensitive film thickness controllable precise
And preparation method thereof.
Background technology
With the development of silicon substrate MEMS technology, silicon substrate MEMS pressure sensor reaches its maturity, by its high sensitivity, height
Precision, low-power consumption, small volume, the low advantage of cost, have captured most of market of pressure sensor.Consider performance,
Silicon substrate MEMS pressure sensor under the indexs such as cost, prior art can meet the city in the fields such as mobile phone, automotive electronics
Field demand.But, need accurately to measure extra small pressure change for central air conditioner system etc., only high-performance ultra-low volume
The pressure sensor of journey (KPa grades) can just accomplish the real-time monitoring changed to slight pressure, and prior art or can not accomplish
Performance is sufficiently high (high sensitivity, high linearity), or can not accomplish that high uniformity, high finished product rate and low cost high-volume are raw
Production, thus there is a very big market has openings always in the type differential pressure pick-up field.
It is always a problem being not yet fully solved to manufacture high performance ultralow range pressure sensor, and its core technology is exactly such as
What solves the problems, such as power sensitive film thickness exact controllability, uniformity and high finished product rate.Industrial quarters still lacks low cost, can measured at present
The product of production caters to the market demand to little differential pressure sensor such as central air conditioning system and intelligent domestic system.Because needing pole
High sensitivity, the power sensitive film of little differential pressure sensor must be made to sufficiently large (diameter 1mm) and sufficiently thin (thickness
1~2 μm).The uniformity and yield rate of this big and thin power sensitive film are difficult to control in industry manufacture.In pressure detecting
During, the mechanical non-linearity that big and flat film is introduced by its large deflection can bring be difficult to compensate for non-linear to testing result,
[M.H.Bao,Micro Mechanical Transducers-Pressure Sensors,Accelerometers and Gyroscopes,
Amsterdam:Elsevier,2000].Introduce beam-film-island structure to reinforce power sensitive film, large deflection can be avoided to a certain extent,
Stress caused by impressed pressure can also concentrate on beam-film-island structure upper surface to ensure that sensor detects high sensitivity, [S. simultaneously
Hein,V.Schliehting,E.Obermeier,“Piezoresistive silicon sensor for very low pressure based on
the concept of stress concentration”,in Digest Tech.Papers Transducers‘93,Japan,1993,pp.
628-631].Fudan University in Shanghai professor Bao Minhang has delivered a kind of sensitive thin film structure of beam-film-island structure, can realize simultaneously thin
Membrane stress concentration, high sensitivity and low nonlinearity degree, [H.Yang, S.Shen, M.Bao, et al, " A pressure transducer
with a single-sided multilevel structure by maskless etching technology”,Mechatronics,vol.8,
1998,pp.585-593].However, there is the deficiency for being difficult to overcome as follows in this structure：(1) it is this without etching self-stopping technology mechanism
Traditional two-sided bulk micromachining make power sensitive film mode cause itself it is difficult to ensure that the uniformity of power sensitive film thickness and
The controllability of thickness, so as to cause the uncertainty of the non-linear and sensitivity of sensor output.Therefore, it is difficult to ensure product
The uniformity and high finished product rate of energy；(2) the differential pressure pick-up physical dimension of this processing mode is very big, complex process, therefore
Be not suitable for low-cost, high-volume production.Represent the Robert Bosch, STMicroelectronics of world today's highest level with
And the single-sided process of TDK companies, the high range absolute pressure sensor based on flat film can only be manufactured, the gas in mobile phone is primarily adapted for use in
Pressure meter [M.Boehringer, H.Artmann, K.Witt, " Porous silicon in a semiconductor manufacturing
environment”,J Microelectromech.Syst.vol.21,2012,pp.1375-1381]。
Shanghai Inst. of Microsystem and Information Technology, Chinese Academy of Sci Wang Jia farmlands are developed recently a kind of new bulk silicon technological MIS
(Microholes Interetch＆Sealing) manufacturing process, [J.C.Wang, Xinxin Li, " Package-friendly
piezoresistive pressure sensors with on-chip integrated packaging-stress-suppressed suspension
(PS3)technology”,J.Micromech.Microeng.Vol.23,2013045027].This single silicon-chip single-sided process can lead to
Cross out anisotropic wet corrosion after aperture and form cavity under monocrystalline silicon thin film.MIS technology has been widely used for manufacturing pressure
Sensor, acceleration transducer, microflow sensor, system for detecting tire pressure even biochemical sensor.Than traditional silicon substrate MEMS
Pressure sensor, the pressure sensor manufactured based on MIS technology has that technique is simple, cost compatible with IC preparation technologies is low
The advantage such as honest and clean, has had the major companies such as product batch production and Robert Bosch, STMicroelectronics and TDK to compete
Market.But be limited to MIS technology and also be difficult to manufacture sufficiently thin power sensitive film (1~2 μm) in itself, main cause is as follows：MIS
The power sensitive thin film that technique makes is monocrystalline silicon thin film, relies primarily on KOH (or TMAH) etchant solutions and passes through miniature release aperture
Corrode monocrystalline silicon to form cavity and the monocrystalline silicon power sensitive thin film above cavity in silicon chip inner transverse, due to the 8 of cavity
Individual face is (111) crystal face, and the lower surface (that is, the upper surface of cavity) of monocrystalline silicon power sensitive thin film is also (111) crystal face,
Therefore when its forming process relies primarily on KOH (or TMAH) alkaline corrosion solution corrosion (111) crystal faces and (110) crystal face
To realize, (wherein, KOH corrodes the corrosion speed between (111) crystal face and (110) crystal face to corrosion rate difference between the two
Rate is than probably about 1:50 or so；The corrosion rate ratio that TMAH corrodes between (111) crystal face and (110) crystal face is general about
1:40 or so).Because KOH (or TMAH) solution not only corrodes (110) crystal face in corrosion process, while also corroding
(111) crystal face, therefore it is not have at all the monocrystalline silicon thin film of only 2 μm or thinner of thickness for corroding using MIS technology
Method is accomplished.Therefore, it is this that ultra micro differential pressure pick-up power sensitive film thickness structure can not be solved based on simple MIS technology
The manufacturing issue accurately controlled.
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 difference of power sensitive film thickness controllable precise
Sensing arrangement and preparation method thereof is pressed, is difficult for solving high sensitivity pressure sensor sensitive thin film thickness structure in the prior art
The problem of accurate control.
In order to achieve the above objects and other related objects, the present invention provides a kind of differential pressure sensing knot of power sensitive film thickness controllable precise
Structure, the differential pressure sensing arrangement of the power sensitive film thickness controllable precise at least includes：
One monocrystalline silicon substrate；
One pressure reference cavity, is formed inside the monocrystalline silicon substrate；
One pressure sensitive cells, including polysilicon power sensitive thin film on the pressure reference cavity, positioned at the polysilicon
The monocrystalline silicon stress concentration structure of power sensitive thin film upper surface and four positioned at the monocrystalline silicon stress concentration structure upper surface
Piezo-resistance；
Via, is communicated through the back side of the monocrystalline silicon substrate with the pressure reference cavity.
Preferably, the monocrystalline silicon substrate is the monocrystalline silicon substrate of (111) crystal face.
Preferably, in addition to multiple pads that each piezo-resistance of correspondence is connected by lead.
Preferably, the polysilicon power sensitive thin film is hexagonal polysilicon silicon thin film, and the pressure reference cavity is to comply with described many
The hexagon cavity of crystal silicon power sensitive thin film shape.
It is highly preferred that the equal edge in six sides of the polysilicon power sensitive thin film<110>Crystal orientation is arranged.
Preferably, the monocrystalline silicon stress concentration structure includes the monocrystalline silicon layer positioned at intermediate layer, and positioned at the monocrystalline silicon layer
The silicon oxide layer on upper and lower surface, the silicon oxide layer thickness of upper and lower layer is equal.
It is highly preferred that the monocrystalline silicon stress concentration structure edge<211>Crystal orientation is arranged.
Preferably, the piezo-resistance in the monocrystalline silicon stress concentration structure is four pouring-in monocrystalline silicon piezo-resistances, is set respectively
The stress concentration position of the monocrystalline silicon stress concentration structure upper surface is placed in, four piezo-resistances are relative to the monocrystalline silicon stress
The center of concentrating structure is centrosymmetric distribution, connects into favour stone full-bridge detection circuit.
Preferably, the via is circular configuration, and the thickness of the polysilicon power sensitive thin film is controlled by the size of the via
Degree, the thickness of the more big polysilicon power sensitive thin film of size is thicker.
In order to achieve the above objects and other related objects, the present invention provides a kind of differential pressure sensing knot of power sensitive film thickness controllable precise
The preparation method of structure, at least includes：
S1：One monocrystalline silicon substrate is provided, the first oxide skin(coating) is formed on the monocrystalline silicon substrate, is needing to make piezo-resistance
Region remove first oxide skin(coating), the monocrystalline silicon substrate is injected ions into form piezo-resistance, in first oxygen
The first passivation protection layer is deposited in compound layer, in first passivation protection layer, first oxide skin(coating) and the monocrystalline silicon substrate
Compartment of terrain makes multiple miniature release apertures on piece, determines the thickness of monocrystalline silicon stress concentration structure；
S2：In the first passivation protection layer surface, the side wall of the miniature release aperture and the passivation protection of bottom deposit second layer,
Reactive ion etching falls the second passivation protection layer of the miniature release aperture bottom, then carries out miniature described in deep reaction ion etching release
Monocrystalline silicon substrate below discharge hole, determines the depth of pressure reference cavity；
S3：The monocrystalline silicon layer that wet etching goes out where monocrystalline silicon stress concentration structure and the pressure ginseng below the monocrystalline silicon layer
Cavity is examined, the second oxide skin(coating) is formed on each surface of the pressure reference cavity；
S4：Deep reaction ion etching via is used at the back side of the monocrystalline silicon substrate, the pressure reference cavity following table is etched to
It is automatically stopped after second oxide skin(coating) in face, then removes the second oxide of the via and the pressure reference cavity junction
Layer；
S5：Deposit polycrystalline silicon fills the miniature release aperture, until each surface of the pressure reference cavity covers one layer of polycrystalline
Silicon thin film, the thickness of the polysilicon membrane is accurately controlled by the miniature release aperture with the via structure size, with many
Crystal silicon fills up the time on the basis of the miniature release aperture time, is increased according to the thickness of depositing polysilicon film difference on fiducial time
Plus respective amount sedimentation time；
S6：The polysilicon membrane of the monocrystalline silicon substrate upper surface is removed, lead wire through substrate and pad is made；
S7：Graphical monocrystalline silicon stress concentration structure, silicon deep reaction ion etching falls in addition to the monocrystalline silicon stress concentration structure
The monocrystalline silicon thin layer of remainder to second oxide skin(coating) is automatically stopped, and removes what is be exposed with reactive ion etching technology
Second oxide skin(coating), obtains the polysilicon power sensitive thin film of polysilicon layer formation.
Preferably, the monocrystalline silicon substrate is that N-type list is thrown or double monocrystalline silicon substrates for throwing (111) crystal face.
Preferably, the miniature release aperture is two row along the monocrystalline silicon substrate<211>Crystal orientation equidistantly makes and parallel arrangement
Multiple square miniature release apertures.
Preferably, the size of the miniature release aperture determines the deposition fiducial time of the polysilicon layer, the miniature release aperture
Depth determines the thickness of the monocrystalline silicon stress concentration structure.
It is highly preferred that the size of the miniature release aperture is 4~24 μm2。
Preferably, the via is circular configuration, and its radius is 5~50 μm.
As described above, differential pressure sensing arrangement of power sensitive film thickness controllable precise of the present invention and preparation method thereof, has with following
Beneficial effect：
The present invention is made using thin-film technique (TUB, Thin-film Under Bulk) under the body silicon of original creation, and polysilicon power sensitivity is thin
Film is deposited over the monocrystalline silicon layer lower surface after silicon bulk fabrication, and one layer of oxidation is clipped between monocrystalline silicon layer and polysilicon power sensitive thin film
Silicon layer；Then monocrystalline silicon layer formation monocrystalline silicon stress concentration structure is etched by dry method self-stopping technology, finally removes silicon oxide layer exposure
Go out polysilicon power sensitive thin film, present invention process can prepare the polysilicon power sensitive thin film that thickness is thinner than under 2 μm, greatly improve
The uniformity and high finished product rate of high sensitivity pressure sensing structure sensitive thin film structure processing, are adapted to produce in enormous quantities.
Brief description of the drawings
Fig. 1 is shown as the differential pressure sensing arrangement three dimensional structure diagram of the power sensitive film thickness controllable precise of the present invention.
Fig. 2 is shown as the differential pressure sensing arrangement three-dimensional structure partial cutaway schematic of the power sensitive film thickness controllable precise of the present invention.
Fig. 3 a-3i are shown as the technological process of the preparation method of the differential pressure sensing arrangement of the power sensitive film thickness controllable precise of the present invention
Figure.
Fig. 4 is shown as the curve of output of the differential pressure sensing arrangement of the power sensitive film thickness controllable precise of the present invention.
Component label instructions
The differential pressure sensing arrangement of 1 power sensitive film thickness controllable precise
11 monocrystalline silicon substrates
12 pressure reference cavitys
13 pressure sensitive cells
131 polysilicon power sensitive thin films
132 monocrystalline silicon stress concentration structures
1321 first silicon oxide layers
1322 monocrystalline silicon layers
1323 second silicon oxide layers
133 piezo-resistances
134 pads
14 vias
21 first passivation protections layer
22 miniature release apertures
23 second passivation protections layer
24 polysilicon membranes
25 leads
S1~S7 steps
Embodiment
Illustrate embodiments of the present invention below by way of specific instantiation, those skilled in the art can be as disclosed by this specification
Content understand easily the present invention other advantages and effect.The present invention can also add by way of a different and different embodiment
To implement or apply, the various details in this specification can also be based on different viewpoints and application, in the essence without departing from the present invention
God is lower to carry out various modifications or alterations.
Refer to Fig. 1~Fig. 4.It should be noted that the diagram provided in the present embodiment only illustrates the present invention's in a schematic way
Basic conception, then in schema only display with relevant component in the present invention rather than according to component count during actual implement, shape and
Size is drawn, and it is actual when implementing, and kenel, quantity and the ratio of each component can be a kind of random change, and its assembly layout type
State may also be increasingly complex.
It is ultra-thin in ultra micro differential pressure pick-up especially for solving in order to solve traditional differential pressure sensors structure and manufacture craft problem
And the film thickness exact controllability problem in large scale power sensitive film manufacturing process, it is quick thin that the present invention proposes a kind of new power
Thin-film technique (TUB, Thin-film Under Bulk) is made under the differential pressure sensing arrangement of film thickness controllable precise and its body silicon of original creation
Preparation Method.Thin-film technique (TUB) is ingenious in each step etching under the body silicon of the present invention introduces etching self-stopping technology mechanism, makes
Uncontrollable factor in must etching can be ignored to the influence that MEMS is processed.Particularly TUB techniques can be by miniature
Release aperture and circular vias come it is accurate control the thickness of polysilicon power sensitive film and can prepare that film thickness is most thin to be smaller than 1 μm, with
Traditional power sensitive film preparation technology is compared, and these advantages substantially increase the processing of high sensitivity pressure sensor sensitive thin film structure
Uniformity, improves the ratio defective product of sensor, suitable for requirements of mass production.
As shown in Fig. 1~Fig. 2, the present invention provides a kind of differential pressure sensing arrangement 1 of power sensitive film thickness controllable precise, and the power is quick
The differential pressure sensing arrangement 1 of film thickness controllable precise at least includes：One monocrystalline silicon substrate 11, a pressure reference cavity 12, one pressure
Power sensing unit 13, two vias 14.
Specifically, as shown in Figures 1 and 2, the monocrystalline silicon substrate 11 is the monocrystalline silicon substrate of (111) crystal face.
Specifically, as shown in Figures 1 and 2, the pressure reference cavity 12, is formed inside the monocrystalline silicon substrate 11.
The pressure reference cavity 12 is the cavity for complying with the shape of polysilicon power sensitive thin film 131, is six sides in the present embodiment
Shape structure, the pressure reference cavity 12 is located at the lower section of the polysilicon power sensitive thin film 131, for making the polysilicon power
Sensitive thin film 131 is hanging；Each face of the surrounding of pressure reference cavity 12 is covered by the uniform polysilicon membrane of a layer thickness, its
Polysilicon membrane is the polysilicon power sensitive thin film 131 at the middle and upper levels, and the film thickness in each face and the polysilicon power are sensitive
The thickness of film 131 is identical；The depth of the pressure reference cavity 12 is controllable, when the differential pressure of the power sensitive film thickness controllable precise
When pressure differential between the front and back of sensing arrangement 1 exceedes full scale, rational pressure reference cavity depth design can be polycrystalline
Silicon power sensitive thin film provides reliable overload protection, and the depth of the pressure reference cavity 12 can be done specifically according to actual application environment
Setting, specific setting is not done herein.
Specifically, as shown in Figures 1 and 2, the pressure sensitive cells 13 include being located on the pressure reference cavity 12
Polysilicon power sensitive thin film 131, the monocrystalline silicon stress concentration structure 132 positioned at the upper surface of polysilicon power sensitive thin film 131,
Four piezo-resistances 133 positioned at the upper surface of monocrystalline silicon stress concentration structure 132, and it is multiple by lead connection correspondence
The pad 134 of each piezo-resistance 133.
More specifically, as shown in Figures 1 and 2, in the present embodiment, the polysilicon power sensitive thin film 131 is that hexagon is more
Polycrystal silicon film, its equal edge in six sides<110>Crystal orientation is arranged, and the polysilicon power sensitive thin film 131 is used to perceive external pressure change.
In the present embodiment, the monocrystalline silicon stress concentration structure 132 is " string " font, edge<211>Crystal orientation is arranged, and the monocrystalline silicon should
Power concentrating structure 132 includes the monocrystalline silicon layer 1322 positioned at intermediate layer, and the first oxidation positioned at the monocrystalline silicon layer upper surface
Second silicon oxide layer 1323 of silicon layer 1321, lower surface；Wherein, the silicon oxide layer thickness of upper and lower layer is equal, therefore remnants should
Power it is in the same size, both eliminated adverse effect of the thin layer of silicon oxide residual stress to the mechanical property of pressure sensitive cells 13, significantly
The detection performance of sensor is improved, while the silicon oxide layer of the lower surface of monocrystalline silicon stress concentration structure 132 is follow-up dry method again
Etch the monocrystalline silicon stress concentration structure 132 and provide etching self-stopping technology purposes, it is to avoid the polysilicon power sensitive thin film 131
Damaged by dry etching.Piezo-resistance 133 in the monocrystalline silicon stress concentration structure 132 is four pouring-in monocrystalline silicon pressures
Quick resistance, respectively on the stress concentration position of the upper surface of monocrystalline silicon stress concentration structure 132, i.e. the monocrystalline silicon
The two ends of stress concentration structure 132 and middle two side position.Wherein, two piezo-resistances at two ends external pressure effect under by
To the increase of tension resistance, two piezo-resistances of middle both sides are reduced by compression resistance, and four piezo-resistances 133 are relative
It is centrosymmetric distribution in the center of the monocrystalline silicon stress concentration structure 132, a complete favour is interconnected into by aluminum steel respectively
This full-bridge detects circuit.
Specifically, as shown in Figures 1 and 2, the via 14 is joined through the back side of the monocrystalline silicon substrate 11 with the pressure
Examine cavity 12 to communicate, can realize that the pressure reference cavity 12 is connected from different atmospheric pressures by the via 14.In this reality
Apply in example, the via 14 is circular configuration, and the polysilicon power sensitive thin film 131 is controlled by the size of the via 14
Thickness, the thickness of the more big polysilicon power sensitive thin film 131 of size is thicker.
As shown in Fig. 3 a~Fig. 3 i, the present invention also provides a kind of preparation side of the differential pressure sensing arrangement of power sensitive film thickness controllable precise
Thin-film technique (TUB, Thin-film Under Bulk) preparation method at least comprises the following steps under method, the body silicon：
Step S1：One monocrystalline silicon substrate 11 is provided, the first oxide skin(coating) is formed on the monocrystalline silicon substrate 11, system is being needed
The region for making piezo-resistance 133 removes first oxide skin(coating), injects ions into the monocrystalline silicon substrate 11 to form pressure-sensitive electricity
Resistance 133, deposits the first passivation protection layer 21 on first oxide skin(coating), in first passivation protection layer 21, institute first
Compartment of terrain makes multiple miniature release apertures 22 on oxide skin(coating) and the monocrystalline silicon substrate 11, when determining the benchmark of polysilicon deposition
Between and monocrystalline silicon stress concentration structure thickness.
Specifically, as shown in Figure 3 a, the monocrystalline silicon substrate 11 is that N-type list is thrown or double monocrystalline silicon substrates for throwing (111) crystal face
Piece, in the present embodiment, its size are 1.2mm × 1.2mm × 0.45mm.Using the method for thermal oxide in the monocrystalline silicon substrate
11 surface forms oxide skin(coating) 21, in the present embodiment, and first oxide skin(coating) is the first silicon oxide layer 1321, it is determined that
The making region of piezo-resistance 133, first silicon oxide layer 1321 in piezo-resistance 133 region is removed by etching, by boron from
Son, which is infused in the monocrystalline silicon substrate 11, forms the piezo-resistance 133.Pass through on first silicon oxide layer 1321
LPCVD (Low Pressure Chemical Vapor Deposition, low-pressure chemical vapor deposition) TEOS (Tetraethyl
Orthosilicate, tetraethoxysilane) the first passivation protection of low temperature depositing layer 21, in the present embodiment, first passivation is protected
Sheath 21 is silicon oxide layer.By reactive ion etching in first passivation protection layer 21 and first silicon oxide layer 1321
Upper compartment of terrain makes multiple miniature release apertures 22, and the miniature release aperture 22 is two row along the monocrystalline silicon substrate 11<211>
Crystal orientation equidistantly make and parallel arrangement multiple square miniature release apertures, the size of the miniature release aperture 22 determines follow-up many
The fiducial time of crystal silicon deposition, the size of the miniature release aperture 22 is 4~24 μm2, in the present embodiment, the miniature release
The size in hole 22 is 3 μm of 3 μ m.The miniature release is increased on the monocrystalline silicon substrate 11 by silicon deep reaction ion etching
The depth in hole 22, the depth of the miniature release aperture 22 is the thickness of follow-up monocrystalline silicon stress concentration structure 132.
Step S2：It is blunt in first passivation protection layer, 21 surface, the side wall of the miniature release aperture 22 and bottom deposit second
Change protective layer 23, reactive ion etching falls the second passivation protection layer 23 of the bottom of miniature release aperture 22, then carries out deep reaction
The monocrystalline silicon substrate 11 of the miniature lower section of release aperture 22, determines the depth of pressure reference cavity 12 described in ion etching.
Specifically, as shown in Figure 3 b, using the second passivation protection of LPCVD TEOS low temperature depositings layer 23, in the present embodiment,
The second passivation protection layer 23 is silicon oxide layer.As shown in Figure 3 c, the miniature release aperture is removed using reactive ion etching
The silica of 22 bottoms, then using the monocrystalline silicon substrate 11 of the miniature lower section of release aperture 22 described in deep reaction ion etching, define institute
The depth of pressure reference cavity 12 is stated, in the present embodiment, the depth of the pressure reference cavity 12 is 20 μm.
Step S3：Wet etching goes out the monocrystalline silicon layer 1322 at the place of monocrystalline silicon stress concentration structure 132 and positioned at the monocrystalline silicon
The pressure reference cavity 12 of the lower section of layer 1322, the second oxide skin(coating) is formed on each surface of the pressure reference cavity 12.
Specifically, as shown in Figure 3 d, using monocrystalline described in TMAH (TMAH) corrosive liquid anisotropic etch
Silicon chip 11 after eight (111) faces whole exposure of the pressure reference cavity 12 until stop, the formation monocrystalline silicon stress
Monocrystalline silicon layer 1322 where concentrating structure 132 and its pressure reference cavity 12 positioned at the lower section of monocrystalline silicon layer 1322, and
Remaining the first passivation protection layer 21 and the second passivation protection layer 23 is removed using BOE corrosive liquids.As shown in Figure 3 e, use
Thermal oxidation technology forms the second silicon oxide layer 1323 on eight faces of the inner side of pressure reference cavity 12.
Step S4：Deep reaction ion etching via 14 is used at the back side of the monocrystalline silicon substrate 11, the pressure ginseng is etched to
It is automatically stopped after the second oxide skin(coating) for examining the lower surface of cavity 12, then removes the via 14 and the pressure reference cavity 12
Second oxide skin(coating) of junction.
Specifically, as illustrated in figure 3f, using the back side of monocrystalline silicon substrate described in deep reaction ion etching 11, it is etched to the pressure
Power is automatically stopped after second oxide layer with reference to the lower surface of cavity 12, then using second oxygen at the reactive ion etching removal back side
Change layer, form the via 14, the via is circular configuration, and its radius is 5~50 μm, in the present embodiment, is set as
10μm。
Step S5：Deposit polycrystalline silicon fills the miniature release aperture 22, until each surface of the pressure reference cavity 12 is covered
One layer of polysilicon membrane 24 of lid, the thickness of the polysilicon membrane 24 is by the miniature release aperture 22 and the knot of the via 14
Structure size is accurately controlled, by polysilicon fill up the miniature release aperture time on the basis of the time, according to depositing polysilicon film
Thickness difference on fiducial time increase respective amount sedimentation time.
Specifically, as shown in figure 3g, deposit polycrystalline silicon fills the miniature release aperture 22, and described miniature release is filled up with polysilicon
Time on the basis of the time of discharge hole 22, respective amount is increased on fiducial time according to the thickness of depositing polysilicon film 24 difference and sunk
The product time, each surface of the pressure reference cavity 12 covers one layer of polysilicon membrane 24.
Step S6：As illustrated in figure 3h, the polysilicon membrane 24 of the removal upper surface of monocrystalline silicon substrate 11, making fairlead,
Lead 25 and pad.
Step S7：Graphical monocrystalline silicon stress concentration structure, silicon deep reaction ion etching falls except the monocrystalline silicon stress concentration structure
Monocrystalline silicon layer to the second oxide skin(coating) of remainder is automatically stopped beyond 132, is removed and is exposed with reactive ion etching technology
The second oxide skin(coating), expose polysilicon layer formation polysilicon power sensitive thin film 1321.
Specifically, as shown in figure 3i, it is fallen in addition to the monocrystalline silicon stress concentration structure 132 using silicon deep reaction ion etching
The monocrystalline silicon substrate 11 of remaining part point, is automatically stopped to the second oxide skin(coating), then removes the second oxide with reactive ion etching technology
Layer, exposes the polysilicon power sensitive thin film 131, the polysilicon power sensitive thin film 131 is hexagonal structure, in this reality
Apply in example, by the thickness of the polysilicon power sensitive thin film 131, accurately control is 2 μm.
As shown in figure 4, the differential pressure sensing arrangement 1 of the power sensitive film thickness controllable precise to being machined in the present embodiment carry out it is comprehensive
Performance test is closed, test result shows to amplify without any electric signal, and sensitivity is 13.36mV/kPa in 1000Pa ranges, non-
The linearity only has 0.31%FS, and noise is less than 0.01mV, and distinguishable 1-2Pa pressure change meets answering for central air conditioner system
With requiring.In addition the polysilicon power sensitive thin film thickness uniform, controllable in the differential pressure sensing arrangement that embodiment is processed, uniformity is good,
High yield rate, this has benefited from the differential pressure sensing arrangement and corresponding TUB manufacturing process of the present invention completely.
As described above, differential pressure sensing arrangement of power sensitive film thickness controllable precise of the present invention and preparation method thereof, has with following
Beneficial effect：
The present invention is made using thin-film technique (TUB, Thin-film Under Bulk) under the body silicon of original creation, and polysilicon power sensitivity is thin
Film is deposited over the monocrystalline silicon layer lower surface after silicon bulk fabrication, and one layer of oxidation is clipped between monocrystalline silicon layer and polysilicon power sensitive thin film
Silicon layer；Then monocrystalline silicon layer formation monocrystalline silicon stress concentration structure is etched by dry method self-stopping technology, finally removes silicon oxide layer exposure
Go out polysilicon power sensitive thin film.Etched from tradition by micromechanics or the monocrystalline silicon power sensitive thin film of wet etching processing is different, by
In polysilicon power sensitive thin film of the invention in whole technical process not by any etching injury, its thickness is completely by LPCVD
Deposited polycrystalline silicon thin film is determined and thickness uniform, controllable, therefore to substantially increase high sensitivity pressure sensing structure sensitivity thin by the present invention
The uniformity and high finished product rate of membrane structure processing, are adapted to produce in enormous quantities.
In summary, the present invention provides a kind of differential pressure sensing arrangement of power sensitive film thickness controllable precise, including：One monocrystalline silicon substrate
Piece；One pressure reference cavity, is formed inside the monocrystalline silicon substrate；One pressure sensitive cells, including positioned at pressure ginseng
Examine the polysilicon power sensitive thin film on cavity, the monocrystalline silicon stress concentration structure positioned at the polysilicon power sensitive thin film upper surface,
And four piezo-resistances positioned at the monocrystalline silicon stress concentration structure upper surface；Via, through the back of the body of the monocrystalline silicon substrate
Face is communicated with the pressure reference cavity.Made using thin-film technique under the body silicon of original creation, polysilicon power sensitive thin film is deposited over
Monocrystalline silicon layer lower surface after silicon bulk fabrication, clips one layer of silicon oxide layer between monocrystalline silicon layer and polysilicon power sensitive thin film；Then
Monocrystalline silicon layer formation monocrystalline silicon stress concentration structure is etched by dry method self-stopping technology, silicon oxide layer is finally removed and exposes polysilicon power
Sensitive thin film.The present invention substantially increases the uniformity and high finished product rate of high sensitivity pressure sensor sensitive thin film structure processing,
It is adapted 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 to be familiar with this skill
The personage of art all can carry out modifications and changes under the spirit and scope without prejudice to the present invention to above-described embodiment.Therefore, such as
Those of ordinary skill in the art without departing from disclosed spirit with completed under technological thought all etc.
Modifications and changes are imitated, should be covered by the claim of the present invention.
Claims (15)
1. a kind of differential pressure sensing arrangement of power sensitive film thickness controllable precise, it is characterised in that the power sensitive film thickness controllable precise
Differential pressure sensing arrangement at least includes：
One monocrystalline silicon substrate；
One pressure reference cavity, is formed inside the monocrystalline silicon substrate；
One pressure sensitive cells, including polysilicon power sensitive thin film on the pressure reference cavity, positioned at the polycrystalline
The monocrystalline silicon stress concentration structure of silicon power sensitive thin film upper surface and positioned at the monocrystalline silicon stress concentration structure upper surface
Four piezo-resistances；
Via, is communicated through the back side of the monocrystalline silicon substrate with the pressure reference cavity.
2. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 1, it is characterised in that：The monocrystalline silicon
Substrate is the monocrystalline silicon substrate of (111) crystal face.
3. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 1, it is characterised in that：Also include multiple
The pad of each piezo-resistance of correspondence is connected by lead.
4. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 1, it is characterised in that：The polysilicon
Power sensitive thin film is hexagonal polysilicon silicon thin film, and the pressure reference cavity is to comply with the polysilicon power sensitive thin film shape
Hexagon cavity.
5. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 4, it is characterised in that：The polysilicon
The equal edge in six sides of power sensitive thin film<110>Crystal orientation is arranged.
6. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 1, it is characterised in that：The monocrystalline silicon
Stress concentration structure includes the monocrystalline silicon layer positioned at intermediate layer, and the silicon oxide layer positioned at the upper and lower surface of the monocrystalline silicon layer,
The silicon oxide layer thickness of upper and lower layer is equal.
7. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 6, it is characterised in that：The monocrystalline silicon
Stress concentration structure edge<211>Crystal orientation is arranged.
8. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 1, it is characterised in that：The monocrystalline silicon
Piezo-resistance in stress concentration structure is four pouring-in monocrystalline silicon piezo-resistances, is respectively arranged at the monocrystalline silicon stress collection
The stress concentration position of middle structure upper surface, during four piezo-resistances are in relative to the center of the monocrystalline silicon stress concentration structure
The heart is symmetrical, connects into favour stone full-bridge detection circuit.
9. the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 1, it is characterised in that：The via is
Circular configuration, the thickness of the polysilicon power sensitive thin film, the more big polycrystalline of size are controlled by the size of the via
The thickness of silicon power sensitive thin film is thicker.
10. a kind of preparation method of the differential pressure sensing arrangement of power sensitive film thickness controllable precise, it is characterised in that comprise the following steps：
S1：One monocrystalline silicon substrate is provided, the first oxide skin(coating) is formed on the monocrystalline silicon substrate, is needing to make pressure-sensitive
The region of resistance removes first oxide skin(coating), the monocrystalline silicon substrate is injected ions into form piezo-resistance, in institute
State deposited on the first oxide skin(coating) the first passivation protection layer, first passivation protection layer, first oxide skin(coating) and
Compartment of terrain makes multiple miniature release apertures on the monocrystalline silicon substrate, confirms the thickness of monocrystalline silicon stress concentration structure；
S2：In the first passivation protection layer surface, the side wall of the miniature release aperture and the passivation protection of bottom deposit second
Layer, reactive ion etching falls the second passivation protection layer of the miniature release aperture bottom, then carries out deep reaction ion etching institute
The monocrystalline silicon substrate below miniature release aperture is stated, the depth of pressure reference cavity is determined；
S3：Monocrystalline silicon layer and the pressure below the monocrystalline silicon layer that wet etching goes out where monocrystalline silicon stress concentration structure
Power refers to cavity, and the second oxide skin(coating) is formed on each surface of the pressure reference cavity；
S4：Deep reaction ion etching via is used at the back side of the monocrystalline silicon substrate, the pressure reference cavity is etched to
It is automatically stopped after second oxide skin(coating) of lower surface, then removes the of the via and the pressure reference cavity junction
Dioxide layer；
S5：Deposit polycrystalline silicon fills the miniature release aperture, until each surface of the pressure reference cavity covers one layer
Polysilicon membrane, the thickness of the polysilicon membrane is accurately controlled by the miniature release aperture with the via structure size
System, by polysilicon fill up the miniature release aperture time on the basis of the time, exist according to the thickness of depositing polysilicon film is different
Increase respective amount sedimentation time on fiducial time；
S6：The polysilicon membrane of the monocrystalline silicon substrate upper surface is removed, lead wire through substrate and pad is made；
S7：Graphical monocrystalline silicon stress concentration structure, silicon deep reaction ion etching falls except the monocrystalline silicon stress concentration structure
The monocrystalline silicon thin layer of remainder to second oxide skin(coating) is automatically stopped in addition, is removed with reactive ion etching technology sudden and violent
The second oxide skin(coating) exposed, obtains the polysilicon power sensitive thin film of polysilicon layer formation.
11. the preparation method of the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 10, its feature exists
In：The monocrystalline silicon substrate is that N-type list is thrown or double monocrystalline silicon substrates for throwing (111) crystal face.
12. the preparation method of the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 10, its feature exists
In：The miniature release aperture is two row along the monocrystalline silicon substrate<211>Crystal orientation equidistantly make and parallel arrangement it is multiple
Square miniature release aperture.
13. the preparation method of the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 10, its feature exists
In：The size of the miniature release aperture determines the deposition fiducial time of the polysilicon layer, and the depth of the miniature release aperture is determined
The thickness of the fixed monocrystalline silicon stress concentration structure.
14. the preparation method of the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 13, its feature exists
In：The size of the miniature release aperture is 4~24 μm2。
15. the preparation method of the differential pressure sensing arrangement of power sensitive film thickness controllable precise according to claim 10, its feature exists
In：The via is circular configuration, and its radius is 5~50 μm.
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