CN102928153A - Three-dimensional vacuum sensor and preparation method of three-dimensional vacuum sensor - Google Patents
Three-dimensional vacuum sensor and preparation method of three-dimensional vacuum sensor Download PDFInfo
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- CN102928153A CN102928153A CN2012104734486A CN201210473448A CN102928153A CN 102928153 A CN102928153 A CN 102928153A CN 2012104734486 A CN2012104734486 A CN 2012104734486A CN 201210473448 A CN201210473448 A CN 201210473448A CN 102928153 A CN102928153 A CN 102928153A
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Abstract
The invention provides a three-dimensional vacuum sensor and a preparation method of the three-dimensional vacuum sensor, wherein a thermopile and a heater prepared by the method are located on different planes; the thermopile is located below the heater to further implement miniaturization of a thermoelectric vacuum sensor; a dry etching release structure is utilized to avoid a problem that a structural layer is adhered with a substrate in a wet etching release process, and the yield of devices is improved; a silicon cover board is additionally arranged, that is, gas heat conduction between the cover board and the heater is increased so as to be beneficial to improving sensitivity of a thermal radiation vacuum gauge on an end with higher pressure intensity. In additional, the materials and the preparation process of the semiconductor substrate, the thermopile and the micro heater are all frequently used in the semiconductor process, so the three-dimensional vacuum sensor is easily compatible with an existing CMOS (complementary metal oxide semiconductor) process.
Description
Technical field
The present invention relates to a kind of sensor and preparation method thereof, particularly relate to a kind of Three Dimensional Thermal conduction type vacuum transducer and method for making, belong to vacuum technique and micro-electromechanical system field.
Background technology
Vacuum measurement has very widely in fields such as industry, space flight and nuclear fuel material purifications uses, traditional vacuum transducer is of a great variety and volume is larger, has limited them in the utilization in some field, particularly applies in some micro devices and the instrument and meter.In conjunction with developing history and the user demand of vacuum transducer, vacuum meter commonly used has to the trend of miniaturization, integrated, systematization and intelligent direction development at present.MEMS develops rapidly, and developing rapidly of micro-processing technology especially makes the reality that develops into of vacuum transducer microminiaturization.The micro vacuum sensor has following significant advantage: low in energy consumption, measure that sensitivity is higher, range of dynamic measurement improves, volume is little, can be mass, cost is low.
Miniature heat conduction vacuum transducer is a kind of in the micro vacuum sensor, utilizes micro-processing technology to process.Its principle of work: when the distance between the mean free path of the gas molecule parallel flat more different than two temperature is large, the heat that transmits between two flat boards and the proportional relation of molecular number of transferring heat, namely the pyroconductivity of gas changes with the variation of pressure.Miniature heat conduction vacuum transducer is divided into two classes according to the difference of measuring temperature methods: resistor-type (Pi Lani type) vacuum transducer and electrothermic type vacuum transducer (F. V lklein and A. Meier, " Microstructured vacuum gauges and their future perspectives; " Vacuum, vol. 82, no. 4, pp. 420 – 430, Dec. 2007).Traditional electrothermic type vacuum transducer is comprised of two parts: heater section and thermoelectric pile part.The hot junction of thermoelectric pile links to each other with well heater, and cold junction links to each other with silicon substrate, and the magnitude of voltage of thermoelectric pile output has reflected the variation of electrothermic type vacuum transducer ambient air pressure.Traditional electrothermic type vacuum transducer utilizes the body micromachining technology to be made, adopt front wet etching technology (O. Paul, O. Brand, R. Lenggenhager, and H. Baltes, " Vacuum gauging with complementary metal – oxide – semiconductor microsensors. " J. Vac. Sci. Technol. A 13,503 (1995)) and back side wet etching technology (A. W. van Herwaarden, D. C. van Duyn, and J. Groeneweg, " Small-size Vacuum Sensors Based on Silicon Thermopiles. " Sensors and Actuators A 25-27,565 (1991)), silicon substrate material below well heater and the thermoelectric pile is removed, realized well heater, heat isolation between thermoelectric pile and the silicon substrate.
Yet there is following problem in traditional minisize thermoelectric type vacuum transducer method for making:
Well heater and thermoelectric pile are made at grade, have limited the further microminiaturization of electrothermic type vacuum transducer; Adopt wet etching technology releasing structure, have structural sheet easily and the glutinous problem that connects of substrate, reduced the yield rate of device; Because adopt back side wet etching technology to discharge, well heater is very large to the distance of substrate, is difficult to improve the pressure measurement upper limit of electrothermic type vacuum transducer, makes the measurement range of electrothermic type vacuum transducer narrower.
Given this, how to propose a kind of minisize thermoelectric type vacuum transducer and preparation method thereof to overcome above-mentioned shortcoming of the prior art, become present problem demanding prompt solution.
Summary of the invention
The shortcoming of prior art the object of the present invention is to provide a kind of Three-dimensional vacuum sensor and preparation method thereof in view of the above, is used for solving the problem that the prior art yield rate is low, volume is large, measurement range is narrow and measuring accuracy is low.
Reach for achieving the above object other relevant purposes, the invention provides a kind of preparation method of Three-dimensional vacuum sensor, described preparation method comprises at least:
1) provides semi-conductive substrate, draw pad in this Semiconductor substrate preparation by thermoelectric pile structure and thermoelectric pile that the first support membrane wraps up;
2) then the structure deposition one deck sacrifice layer that forms in described step 1) carries out graphical etching to described sacrifice layer, to form the contact hole that is communicated with described the first support membrane at this sacrifice layer;
3) in described step 2) the structure preparation that forms draws pad by micro-heater structure and micro-heater that the second support membrane wraps up;
4) carry out graphical etching at described the second support membrane, etching exposes that described thermoelectric pile is drawn pad and micro-heater is drawn pad, and then described the second support membrane of etching is until form the release through hole that is communicated with described Semiconductor substrate;
5) by described release through hole and utilize dry corrosion process that the described sacrifice layer corrosion between described the first support membrane and the second support membrane is fallen, form curved cavity in described Semiconductor substrate corrosion simultaneously, thereby discharged described thermoelectric pile structure and micro-heater structure;
6) provide a cover plate, form cavity by wet corrosion technique in described cover plate one side, go out aperture to remain potted pressure identical with the external world in the chamber in this cover plate side etch simultaneously; Then utilize the wafer level bonding technology that the side that described cover plate has cavity is bonded on the structure that forms in the described step 5), thereby finish described Three-dimensional vacuum manufacturing of the fiber grating sensors;
7) by scribing a plurality of Three-dimensional vacuum sensor units on the described Semiconductor substrate are separated, and expose simultaneously that described thermoelectric pile is drawn pad and micro-heater is drawn pad.
Alternatively, the material of described sacrifice layer is α-Si, and the thickness of this sacrifice layer is 1 μ m～10 μ m.
Alternatively, the cover plate material in the described step 6) is silicon.
Alternatively, described the first support film contacts by described contact hole with described the second support film, and the heat of described microheater structure generation is transferred to respectively the hot junction of described thermoelectric pile from top to bottom via this second support membrane and the first support membrane.
Alternatively, the release of described Three-dimensional vacuum sensor construction is one step completed, and namely etchant gas corrodes described sacrifice layer and Semiconductor substrate successively by discharging through hole.
Alternatively, described step 1) comprises:
1-1) at described Semiconductor substrate preparation the first dielectric layer, then at this first dielectric layer preparation the first conductive layer, then this first conducting layer figure is etched into strip, as the part of thermocouple structure;
1-2) at described step 1-1) structure deposition the second dielectric layer, then this second dielectric layer carry out graphical etching expose with formation below the fairlead of described the first conductive layer;
1-3) at described the second dielectric layer deposition the second conductive layer, the second conductive layer is carried out graphical etching form specific metal line, and contact the formation thermopair with described the first conductive layer to structure by described fairlead; Described metal line forms the thermoelectric pile structure with described thermopair to structure series connection, and forms simultaneously thermoelectric pile and draw pad;
1-4) at described step 1-3) structure deposition the 3rd dielectric layer that forms, the 3rd dielectric layer, jointly form the first support membrane that wraps up described thermoelectric pile structure with the described second electric matter layer, described the first dielectric layer.
Alternatively, when described Semiconductor substrate is the SOI substrate, described step 1-1) the first dielectric layer in is the buried regions monox of described SOI substrate, and mixes in the top layer silicon of described SOI substrate by ion implantation technology and to form the first conductive layer.When described Semiconductor substrate is silicon substrate, utilize hot growth technique at described silicon substrate preparation silicon oxide layer as described step 1-1) in the first dielectric layer, and the polysilicon layer that mixes in this silicon oxide layer preparation by LPCVD technique is as the first conductive layer.
Alternatively, the material of described the first dielectric layer and the 3rd dielectric layer is monox, and the material of described the second dielectric layer is silicon nitride; Monocrystalline silicon or the polysilicon of the material of described the first conductive layer for mixing, the material of described the second conductive layer is aluminium.
Alternatively, described step 3) comprises:
3-1) at described sacrifice layer deposition the 4th dielectric layer, then deposit the 3rd conductive layer at the 4th dielectric layer, and the 3rd conducting layer figure is etched into resistance strip formation micro-heater structure, form simultaneously micro-heater and draw pad;
3-2) at described step 3-1) deposit successively from bottom to top the 5th dielectric layer and the 6th dielectric layer on the structure that forms, the 5th dielectric layer has formed the second support membrane that wraps up described micro-heater structure jointly with described the 4th dielectric layer, described the 6th dielectric layer.
Alternatively, the material of described the 4th dielectric layer and the 6th dielectric layer is monox, and the material of described the 5th dielectric layer is silicon nitride; The material of described the 3rd conductive layer is aluminium, platinum or tungsten.
Another object of the present invention provides a kind of Three-dimensional vacuum sensor, comprises at least:
The reeded Semiconductor substrate of tool, be suspended from the first support membrane of described groove top, the thermoelectric pile that wrapped up by described the first support membrane, the parallel micro-heater that is suspended from the second support membrane on described the first support membrane, is wrapped up by described the second support membrane and the cover plate that is bonded to described the second support membrane surface.
Alternatively, described Semiconductor substrate is SOI substrate or silicon chip.Alternatively, the material of described cover plate is silicon chip, and the side of this cover plate has aperture, keeps identical pressure with atmosphere outside to keep described Three-dimensional vacuum sensor in package cavity.
Alternatively, the structure of described the first support membrane and the second support membrane is the bottom-up composite dielectric film that is comprised of silicon oxide layer, silicon nitride layer, silicon oxide layer successively.Vertical range between described the first support membrane and the second support membrane is 1 μ m～10 μ m.
Alternatively, described Three-dimensional vacuum sensor comprises that also the micro-heater that is positioned at described cover plate both sides is drawn pad and thermoelectric pile is drawn pad.Described the first support membrane and the second support membrane have contact site, and the heat that described micro-heater produces is sent to the hot junction of described thermoelectric pile by described the second support membrane, described contact site and the first support membrane.The material of described thermoelectric pile structure adopts polysilicon and the metallic aluminium of doped monocrystalline silicon and metallic aluminium or doping; The material of described micro-heater structure adopts aluminium, platinum or tungsten.
As mentioned above, Three-dimensional vacuum sensor of the present invention and preparation method thereof has following beneficial effect:
The thermoelectric pile of the method preparation is positioned on the different planes with well heater, can further realize the microminiaturization of electrothermic type vacuum transducer; Adopt the dry etching releasing structure, can avoid problem in the wet etching dispose procedure, the problem includes: structural sheet and substrate stick the problem that connects, improved the yield rate of device; Increase the silicon cover plate, namely increased the air heat conduction between cover plate and the well heater, be conducive to improve thermal radiation vacuum gauge in the sensitivity of higher gas pressure intensity end.In addition, the material of the Semiconductor substrate that adopts among the present invention, thermoelectric pile and micro-heater and the preparation technology who adopts are commonly used in the semiconductor technology, can be easy to the compatibility with existing CMOS technique.
Description of drawings
Fig. 1 a～Fig. 1 m is shown as the Three-dimensional vacuum sensor preparation technology schematic flow sheet in the embodiment of the invention 1.Wherein, Fig. 1 h～1j is shown as to form and discharges the plane reduced graph in each step in the through hole.
Fig. 2 is shown as the synoptic diagram of the Three-dimensional vacuum sensor construction in the embodiment of the invention 2.
The element numbers explanation
10 silicon substrates
100 cavitys
11 first silicon oxide layers
12,150 ' polysilicon layer
13 first silicon nitride layers
130 fairleads
14,19,151 ' aluminum metal layer
15,15 ' thermopair pair
150,18 ' thermoelectric pile is drawn pad
16 second silicon oxide layers
17 α-Si layer
170 contact holes
18 the 3rd silicon oxide layers
190,13 ' micro-heater
191,17 ' micro-heater is drawn pad
20 second silicon nitride layers
21 the 4th silicon oxide layers
22 discharge through hole
23,16 ' solder layer
24,14 ' cover plate
10 ' Semiconductor substrate
100 ', 140 ' groove
11 ' the first support membranes
110 ', 112 ', 120 ', 122 ' silicon oxide layer
111 ', 121 ' silicon nitride layer
12 ' the second support membranes
S1 ~ S8 step
Embodiment
Below by specific instantiation explanation embodiments of the present invention, those skilled in the art can understand other advantages of the present invention and effect easily by the disclosed content of this instructions.The present invention can also be implemented or be used by other different embodiment, and the every details in this instructions also can be based on different viewpoints and application, carries out various modifications or change under the spirit of the present invention not deviating from.
See also Fig. 1 a to Fig. 1 m, and Fig. 2.Need to prove, the diagram that provides in the present embodiment only illustrates basic conception of the present invention in a schematic way, satisfy only show in graphic with the present invention in relevant assembly but not component count, shape and size drafting when implementing according to reality, kenel, quantity and the ratio of each assembly can be a kind of random change during its actual enforcement, and its assembly layout kenel also may be more complicated.
Embodiment 1
As shown in the figure, the invention provides a kind of preparation method of Three-dimensional vacuum sensor, the method may further comprise the steps:
S1: as shown in Figure 1a, provide semi-conductive substrate, this Semiconductor substrate can be the SOI substrate, or common silicon chip, elects temporarily common silicon substrate 10 in the present embodiment as.Utilize the thermal oxide generating process to prepare the first silicon oxide layer 11 as the first dielectric layer at described silicon substrate 10, then utilize LPCVD technique at these first silicon oxide layer, 11 deposition one deck polysilicon layers 12; Then utilize ion implantation technology that described polysilicon layer 12 is mixed and make its conduction as the first conductive layer, in other embodiments, described the first conductive layer is replaceable monocrystalline silicon for mixing also.The ion that mixes can be N-type or P type ion, is phosphorus, arsenic etc. such as N-type doping adulterant commonly used, and P type doping adulterant commonly used is boron, indium, gallium, aluminium or boron fluoride etc.; Carry out graphical etching at described doped polysilicon 12 at last, etching technics can adopt dry method well-known to those skilled in the art or wet-etching technology, adopt the RIE(reactive ion etching in this enforcement) technique, described polysilicon layer 12 is etched into list structure as the part of thermopair.
Need to prove, when described Semiconductor substrate is elected the SOI substrate as, buried regions monox in this SOI substrate is as the first silicon oxide layer, mixing in the top layer silicon of described SOI substrate makes its conduction, then described top layer silicon graphically is etched into list structure as the part of thermopair.Therefore adopt the SOI substrate to economize to reduce phlegm and internal heat the technique of growth regulation one silica layer, the common silicon substrate of other technique and employing is identical, repeats no more in the present embodiment.
S2: shown in Fig. 1 b, utilize the PECVD(plasma enhanced chemical vapor deposition) structure deposition the second dielectric layer of forming at described step S1 of technique, this second dielectric layer is elected the first silicon nitride layer 13 temporarily as in the present embodiment, then this first silicon nitride layer 13 is carried out graphical etching and form fairlead 130, and expose simultaneously the described polysilicon layer 12 of strip.
S3: shown in Fig. 1 c to Fig. 1 d, at described the first silicon nitride layer 13 depositions the second conductive layer, this second conductive layer is elected aluminum metal layer 14 as in the present embodiment, and adopts vacuum evaporation or sputtering technology preparation; Then aluminum metal layer 14 is carried out graphical etching and form specific wiring layer; Described aluminum metal layer 14 contacts with described polysilicon layer 12 by described fairlead 130 and forms thermopair to 15 structures; This aluminum metal layer 14 forms thermoelectric pile (not shown) structure with described thermopair to 15 structures series connection simultaneously, and forms simultaneously this thermoelectric pile and draw pad 150; Then utilize pecvd process at described aluminum metal layer 14 depositions the 3rd dielectric layer described thermoelectric pile structure to be covered, the 3rd dielectric layer is elected the second silicon oxide layer 16 as in the present embodiment, but be not limited to this, also can select in other embodiments other with present embodiment in the dielectric layer of the 3rd dielectric layer with identical effect.So far, described the second silicon oxide layer 16 and described the first silicon oxide layer 11, the first silicon nitride layer 13 common the first support membranes that form described thermoelectric pile parcel.
S4: shown in Fig. 1 d, at structure deposition one deck sacrifice layer that described step S3 forms, sacrifice layer described in the present embodiment is elected α-Si layer 17 as, but is not limited to this, also can select other sacrificial layer material at other embodiment.Then described α-Si layer 17 is carried out graphical etching, to form the contact hole 170 that is communicated with described the second silicon oxide layer 16 at this α of described thermoelectric pile superstructure-Si layer 17.Need to prove that the thickness of described α-Si layer 17 is 1 μ m～10 μ m, the thickness of α in the present embodiment-Si layer 17 is elected 2 μ m temporarily as, but is not limited to this, and this thickness can change according to the difference of prepared sensor performance.
S5: shown in Fig. 1 e, utilize pecvd process at described α-Si layer 17 deposition the 4th dielectric layer, the 4th dielectric layer is elected temporarily the 3rd silicon oxide layer 18, the three silicon oxide layers as and is contacted with described the second silicon oxide layer 16 by the contact hole 170 on described α-Si layer 17 in the present embodiment.
S6: shown in Fig. 1 e to 1f, at described the 3rd silicon oxide layer 18 preparations the 3rd conductive layer, the 3rd conductive layer is the metal level by evaporation or sputtering technology deposition in the present embodiment, the material of this metal level can be aluminium, platinum or tungsten, elect temporarily aluminum metal layer 19 in the present embodiment as, then described aluminum metal layer 19 is carried out photoetching and corrosion, to form micro-heater 190 structures of resistance strip, form simultaneously micro-heater and draw pad 191.
S7: shown in Fig. 1 g, utilize pecvd process on described micro-heater structure, to deposit successively from bottom to top the 5th dielectric layer and the 6th dielectric layer, the 5th dielectric layer is elected temporarily the second silicon nitride layer 20, the six dielectric layers as and is elected temporarily the 4th silicon oxide layer 21 as in the present embodiment; Described the 3rd silicon oxide layer 18 and described the second silicon nitride layer 20, the 4th silicon oxide layer 21 common the second support membranes that form the sandwich structure of described micro-heater 190 structures of parcel; Then carry out photoetching at described the 4th silicon oxide layer 21, etching exposes that described micro-heater is drawn pad 191 and described thermoelectric pile is drawn pad 150, and then described the second support membrane of etching discharges through hole 22 until expose the described Semiconductor substrate of below to form from top to bottom.The forming process of described release through hole 22 divided for three steps, and is specific as follows:
The first step, at presumptive area from top to bottom successively etching the 6th dielectric layer, the 5th dielectric layer, the 4th dielectric layer, α-Si layer 17, the 3rd dielectric layer, second medium layer and first medium layer, until expose substrate silicon 10, the planimetric map of the release through hole 22 that this stage forms is shown in Fig. 1 h.Second step, again at presumptive area from top to bottom successively etching the 6th dielectric layer, the 5th dielectric layer and the 4th dielectric layer, stop until exposing α-Si layer 17, the purpose in this stage is to remove the second support membrane of presumptive area, can dissipate by second support membrane in this zone with the heat that prevents described micro-heater 190, thereby improve the efficiency of heating surface of this micro-heater 190, the planimetric map of the release through hole 22 that this stage forms is shown in Fig. 1 i.The 3rd step, carry out graphical etching in the zone that second step forms, successively etching α-Si layer 17, the 3rd dielectric layer, second medium layer and first medium layer, until expose substrate silicon 10, the planimetric map of the release through hole 22 that this stage forms is shown in Fig. 1 j, (for making things convenient for view and understanding, Fig. 1 h to Fig. 1 j just demonstrates the part layer of its necessary shape).
Need to prove, described the first support film contacts by the contact hole 170 on described α-Si layer 17 with described the second support film, and the heat that described microheater 190 produces is transferred to the hot junction (being described polysilicon layer 12 and resistance strip aluminum metal film 19 contact jaws) of described thermoelectric pile downwards via this first support film and described the second support film contact site.
Well-known to those skilled in the art is that the stress of dielectric film is the key factor that affects device performance.Generally speaking, the tension stress that dielectric film possesses certain low value is optimal state, and tension stress is excessive, can cause driving voltage too high, even causes film breaks and lost efficacy; Stress is zero, perhaps is rendered as compressive stress, then might make deielectric-coating subside when driving and cause component failure not adding.Because therefore the advantages such as pecvd process has that deposition temperature is low, the deposited film pinhold density is little, good uniformity, step coverage are good become the first-selected technique for preparing dielectric film.Adopt pecvd process to prepare the first support membrane and the second support membrane in the present embodiment, and the first support membrane and the second support membrane dielectric film of the bottom-up sandwich structure that is formed by monox, silicon nitride layer and silicon oxide layer respectively, the silicon oxide layer for preparing in the present embodiment has tension stress, and silicon nitride layer has larger compressive stress.Therefore, the present invention not only has mechanical supporting role, and the stress of dielectric film is had better control by the composite dielectric film of preparation sandwich structure.
S8: shown in Fig. 1 k, utilize dry etch process, pass into the etchant gas of silicon in the described release through hole 22, first the described α between described the first support membrane and the second support membrane-Si layer 17 is eroded, then erode away curved cavity 100 at described silicon substrate 10, thereby discharge described thermoelectric pile structure (not shown) and micro-heater structure 190, realized the heat insulation of described the first support membrane and silicon substrate 10.Described dry etching is known for those skilled in the art are described, does not repeat them here.
S9: shown in Fig. 1 l, utilize the wafer level bonding technology by solder layer 23 bonding one cover plate 24 on described the second support membrane, the present embodiment cover plate adopts the silicon cover plate, and at described silicon cover plate side opening one aperture (not shown) remaining potted in the chamber and extraneous identical pressure, thereby finish described Three-dimensional vacuum manufacturing of the fiber grating sensors.
Need to prove; above described heat conduction vacuum transducer, add a silicon cover plate 24 by bonding; not only can increase vacuum transducer in the measurement sensitivity of higher gas pressure intensity end, strengthen the heat conduction of gas, and can protect sensor away from outside contamination.
S10: shown in Fig. 1 m, by scribing a plurality of described Three-dimensional vacuum sensor unit on the described silicon substrate 10 is separated, and expose simultaneously described micro-heater draw pad 191 and thermoelectric pile draw pad 150.
By the preparation method of Three-dimensional vacuum sensor described above as can be known, because thermoelectric pile of the present invention and well heater are made respectively, and thermoelectric pile is positioned on the different planes with well heater, thermoelectric pile be positioned at micro-heater below, can further realize the microminiaturization of electrothermic type vacuum transducer; Adopt the dry etching releasing structure, can avoid problem in the wet etching releasing structure process, the problem includes: structural sheet and substrate stick the problem that connects, improved the yield rate of device; Increase the silicon cover plate, namely increased the air heat conduction between cover plate and the micro-heater, be conducive to improve thermal radiation vacuum gauge in the sensitivity of higher gas pressure intensity end.In addition, the material of the Semiconductor substrate that adopts among the present invention, thermoelectric pile and micro-heater and the preparation technology who adopts are commonly used in the semiconductor technology, can be easy to existing CMOS technique compatible mutually.
As shown in Figure 2, present embodiment provides a kind of structure of Three-dimensional vacuum sensor, comprises at least: Semiconductor substrate 10 ', the first support membrane 11 ', thermoelectric pile (not shown), the second support membrane 12 ', micro-heater 13 ' and cover plate 14 '.
Described Semiconductor substrate 10 ' a have groove 100 ', this Semiconductor substrate 10 ' can be a common silicon substrate also can be the SOI substrate; Described the first support membrane 11 ' wrap up described thermoelectric pile, and be suspended from described groove 100 ' top take the sidewall of described groove 100 ' periphery as supporting; This first support membrane 11 ' be laminated film, the first support membrane 11 in the present embodiment ' for bottom-up comprise successively the first silicon oxide layer 110 ', the first silicon nitride layer 111 ', the second silicon oxide layer 112 ' the laminated film of sandwich structure, the composite dielectric film of this sandwich structure not only plays machinery and makes effect, can also reach the better control to dielectric film stress.But be not limited to this, described the first support membrane 11 ' can be different structure in other embodiments, all must be contained by claim of the present invention to break away from all equivalences of being finished under disclosed spirit and the technological thought and modify or to change.
Described thermoelectric pile by a plurality of thermopairs to 15 ' be composed in series, described thermopair to 15 ' material adopt the polysilicon layer 150 that mixes ' and aluminum metal layer 151 ', need to prove, in other embodiments, the monocrystalline silicon substitute of the polysilicon layer 150 of described doping ' also can be doped as thermopair to 15 ' a part.The described aluminum metal layer 151 of described polysilicon layer 150 ' be positioned at ' the below, all be the resistance strip, and the described polysilicon 150 of strip ' with aluminum metal layer 151 ' an end link to each other as thermopair to 15 ' the hot junction, other parts have the insulating medium layer isolation.Insulating medium layer in the present embodiment is elected silicon nitride or monox as.
The described thermoelectric pile of described the second support membrane 12 ' wrap up, parallel be suspended from described the first support membrane 11 ' the top, and this second support membrane 12 ' and described the first support membrane 11 ' between have a contact site; Described contact site below for by the first micro-heater 13 that supports film forming 11 ' wrapped up ', this contact site top is for by the hot junction of the second support membrane 12 ' described thermoelectric pile that comprises.The heat of described micro-heater 13 ' generation is sent to the hot junction of described thermoelectric pile by described contact site.In addition, in the present embodiment, described the first support membrane 11 ' and the second support membrane 12 ' between vertical range except contact site be 1 μ m～10 μ m.
Need to prove, described the second support membrane 12 ' be composite dielectric film, the second support membrane 12 described in the present embodiment ' for bottom-up comprise successively the 3rd silicon oxide layer 120 ', the second silicon nitride layer 121 ', the 4th silicon oxide layer 122 ' the laminated film of sandwich structure, with described the first support membrane 11 ' structure and effect identical, do not repeat them here.
Described micro-heater 13 ' material adopts the metal materials such as aluminium, platinum or tungsten, also can adopt through conductive doped semiconductor material, and the 13 ' material of micro-heater described in the present embodiment is elected aluminium temporarily as, and described micro-heater 13 ' be resistance strip.
Described cover plate 14 ' a have groove 140 ', by solder layer 16 ' with described cover plate 14 ' have groove 140 ' one side be bonded to described the second support membrane 12 ' top and described Semiconductor substrate 10 ' package cavity of composition; Described cover plate 14 ' side has the aperture (not shown) in addition to remain potted pressure identical with the external world in the chamber.Present embodiment cover plate 14 ' employing silicon cover plate.
Need to prove; above described heat conduction vacuum transducer by bonding add a cover plate 14 '; not only can increase vacuum transducer in the measurement sensitivity of higher gas pressure intensity end, strengthen the heat conduction of gas, and can protect sensor away from outside contamination.
In addition, described Three-dimensional vacuum sensor also comprise be positioned at the outer micro-heater of described package cavity draw pad 17 ' and thermoelectric pile draw pad 18 '.
In order further to illustrate the effect of Three-dimensional vacuum sensor of the present invention, the below describes its principle of work.
When described micro-heater energising heating, this micro-heater district temperature will rise, and links to each other with micro-heater because the contact site of the first and second support membranes is passed through in the hot junction of described thermoelectric pile, so the hot-side temperature of thermoelectric pile also rises; And the cold junction of this thermoelectric pile is owing to be positioned on the substrate silicon matrix, and its temperature remains environment temperature; Because the Seebeck effect of thermoelectric pile, the temperature difference of hot junction and cold junction are converted into voltage signal output.When the gas pressure intensity around the described micro-heater changes, this micro-heater district changes by the heat of air heat conduction loss, then the temperature in this micro-heater district changes, the voltage of described thermoelectric pile output changes thereupon, therefore by can detect the size of micro-heater ambient gas pressure to the detection of described thermoelectric pile output voltage.
In sum, the invention provides a kind of Three-dimensional vacuum sensor and preparation method thereof, the thermoelectric pile of the method preparation is positioned on the different planes with well heater, thermoelectric pile be positioned at micro-heater below, can further realize the microminiaturization of electrothermic type vacuum transducer; Adopt the dry etching releasing structure, can avoid problem in the wet etching course, the problem includes: structural sheet and substrate stick the problem that connects, improved the yield rate of device; Increase the silicon cover plate, namely strengthened the air heat conduction between cover plate and the well heater, be conducive to improve thermal radiation vacuum gauge in the sensitivity of higher gas pressure intensity end.In addition, the material of the Semiconductor substrate that adopts among the present invention, thermoelectric pile and micro-heater and the preparation technology who adopts are commonly used in the semiconductor technology, can be easy to existing CMOS technique compatible mutually.So the present invention has effectively overcome various shortcoming of the prior art and the tool high industrial utilization.
Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not is used for restriction the present invention.Any person skilled in the art scholar all can be under spirit of the present invention and category, and above-described embodiment is modified or changed.Therefore, have in the technical field under such as and know that usually the knowledgeable modifies or changes not breaking away from all equivalences of finishing under disclosed spirit and the technological thought, must be contained by claim of the present invention.
Claims (19)
1. the preparation method of a Three-dimensional vacuum sensor is characterized in that, described preparation method comprises at least:
1) provides semi-conductive substrate, draw pad in this Semiconductor substrate preparation by thermoelectric pile structure and thermoelectric pile that the first support membrane wraps up;
2) then the structure deposition one deck sacrifice layer that forms in described step 1) carries out graphical etching to described sacrifice layer, to form the contact hole that is communicated with described the first support membrane at this sacrifice layer;
3) in described step 2) the structure preparation that forms draws pad by micro-heater structure and this micro-heater that the second support membrane wraps up;
4) carry out graphical etching at described the second support membrane, expose that described thermoelectric pile is drawn pad and micro-heater is drawn pad, and then from top to bottom described the second support membrane of etching until form the release through hole that is communicated with described Semiconductor substrate;
5) by described release through hole and utilize dry corrosion process that the described sacrifice layer corrosion between described the first support membrane and the second support membrane is fallen, form curved cavity in described Semiconductor substrate corrosion simultaneously, thereby discharged described thermoelectric pile structure and micro-heater structure;
6) provide a cover plate, form cavity by wet corrosion technique in described cover plate one side, go out aperture to remain potted pressure identical with the external world in the chamber in this cover plate side etch simultaneously; Then utilize the wafer level bonding technology that the side that described cover plate has cavity is bonded on the structure that forms in the described step 5), thereby finish described Three-dimensional vacuum manufacturing of the fiber grating sensors;
7) by scribing a plurality of Three-dimensional vacuum sensor units on the described Semiconductor substrate are separated, and expose simultaneously that described thermoelectric pile is drawn pad and micro-heater is drawn pad.
2. according to Three-dimensional vacuum manufacturing of the fiber grating sensors method claimed in claim 1, it is characterized in that: the material of described sacrifice layer is α-Si, and the thickness of this sacrifice layer is 1 μ m～10 μ m.
3. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 1, it is characterized in that: the cover plate material in the described step 6) is silicon.
4. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 1, it is characterized in that: described the first support film contacts by described contact hole with described the second support film, and the heat that described microheater produces is transferred to respectively the hot junction of described thermoelectric pile from top to bottom via this second support membrane and the first support membrane.
5. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 1, it is characterized in that: the release of described Three-dimensional vacuum sensor construction is one step completed, namely etchant gas corrodes described sacrifice layer and Semiconductor substrate successively by discharging through hole.
6. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 1 is characterized in that described step 1) comprises:
1-1) at described Semiconductor substrate preparation the first dielectric layer, then at this first dielectric layer preparation the first conductive layer, then this first conducting layer figure etching, Implantation are formed strip, as the part of thermocouple structure;
1-2) at described step 1-1) structure deposition the second dielectric layer, then this second dielectric layer carry out graphical etching expose with formation below the fairlead of described the first conductive layer;
1-3) at described the second dielectric layer deposition the second conductive layer, the second conductive layer is carried out graphical etching form specific metal line, and contact the formation thermopair with described the first conductive layer to structure by described fairlead; Described metal line forms the thermoelectric pile structure with described thermopair to structure series connection, and forms simultaneously thermoelectric pile and draw pad;
1-4) at described step 1-3) structure deposition the 3rd dielectric layer that forms, the 3rd dielectric layer, jointly form the first support membrane that wraps up described thermoelectric pile structure with the described second electric matter layer, described the first dielectric layer.
7. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 6, it is characterized in that: when described Semiconductor substrate is the SOI substrate, described step 1-1) the first dielectric layer in is the buried regions monox of described SOI substrate, and mixes in the top layer silicon of described SOI substrate by ion implantation technology and to form the first conductive layer.
8. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 6, it is characterized in that: when described Semiconductor substrate is silicon substrate, utilize hot growth technique at described silicon substrate preparation silicon oxide layer as described step 1-1) in the first dielectric layer, and the polysilicon layer that mixes in this silicon oxide layer preparation by LPCVD technique is as the first conductive layer.
9. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 6, it is characterized in that: the material of described the first dielectric layer and the 3rd dielectric layer is monox, the material of described the second dielectric layer is silicon nitride; Monocrystalline silicon or the polysilicon of the material of described the first conductive layer for mixing, the material of described the second conductive layer is aluminium.
10. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 1, it is characterized in that: described step 3) comprises:
3-1) at described sacrifice layer deposition the 4th dielectric layer, then deposit the 3rd conductive layer at the 4th dielectric layer, and the 3rd conducting layer figure is etched into resistance strip formation micro-heater structure, form simultaneously micro-heater and draw pad;
3-2) at described step 3-1) deposit successively from bottom to top the 5th dielectric layer and the 6th dielectric layer on the structure that forms, the 5th dielectric layer has formed the second support membrane that wraps up described micro-heater structure jointly with described the 4th dielectric layer, described the 6th dielectric layer.
11. Three-dimensional vacuum manufacturing of the fiber grating sensors method according to claim 10 is characterized in that: the material of described the 4th dielectric layer and the 6th dielectric layer is monox, the material of described the 5th dielectric layer is silicon nitride; The material of described the 3rd conductive layer is aluminium, platinum or tungsten.
12. a Three-dimensional vacuum sensor is characterized in that, comprises at least:
The reeded Semiconductor substrate of tool, be suspended from the first support membrane of described groove top, the thermoelectric pile that wrapped up by described the first support membrane, the parallel micro-heater that is suspended from the second support membrane on described the first support membrane, is wrapped up by described the second support membrane and the cover plate that is bonded to described the second support membrane surface.
13. Three-dimensional vacuum sensor according to claim 12 is characterized in that: described Semiconductor substrate is SOI substrate or silicon chip.
14. Three-dimensional vacuum sensor according to claim 12 is characterized in that: the material of described cover plate is silicon chip, and the side of this cover plate has aperture, keeps identical pressure with atmosphere outside to keep described Three-dimensional vacuum sensor in package cavity.
15. Three-dimensional vacuum sensor according to claim 12 is characterized in that: the structure of described the first support membrane and the second support membrane is the bottom-up composite dielectric film that is comprised of silicon oxide layer, silicon nitride layer, silicon oxide layer successively.
16. Three-dimensional vacuum sensor according to claim 12 is characterized in that: the vertical range between described the first support membrane and the second support membrane is 1 μ m～10 μ m.
17. Three-dimensional vacuum sensor according to claim 12 is characterized in that: described Three-dimensional vacuum sensor comprises that also the micro-heater that is positioned at described cover plate both sides is drawn pad and thermoelectric pile is drawn pad.
18. Three-dimensional vacuum sensor according to claim 12, it is characterized in that: have contact site between described the first support membrane and the second support membrane, the heat that described micro-heater produces is sent to the hot junction of described thermoelectric pile structure by described the second support membrane, described contact site and described the first support membrane.
19. Three-dimensional vacuum sensor according to claim 12 is characterized in that: the material of described thermoelectric pile adopts the monocrystalline silicon of doping and polysilicon and the metallic aluminium of metallic aluminium or doping; The material of described micro-heater adopts aluminium, platinum or tungsten.
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