CN102520032B - CMUT (Capacitive Micromachined Ultrasonic Transducer)-based biochemical transducer and manufacturing method thereof - Google Patents
CMUT (Capacitive Micromachined Ultrasonic Transducer)-based biochemical transducer and manufacturing method thereof Download PDFInfo
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- CN102520032B CN102520032B CN201110399566.2A CN201110399566A CN102520032B CN 102520032 B CN102520032 B CN 102520032B CN 201110399566 A CN201110399566 A CN 201110399566A CN 102520032 B CN102520032 B CN 102520032B
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Abstract
The invention provides a CMUT (Capacitive Micromachined Ultrasonic Transducer)-based biochemical transducer and a manufacturing method thereof. The CMUT-based biochemical transducer comprises a sensitivity identification material layer, an upper electrode, a silicon dioxide film, a silicon strut, a lower electrode, a silicon dioxide insulating layer and a silicon substrate in sequence from top to bottom. According to the biochemical transducer, the metal lower electrode is completely isolated from the silicon substrate, the method which takes the substrate as the lower electrode in the conventional CMUT based biochemical transducer is replaced, the power consumption is reduced, the electric field strength between the upper electrode and the lower electrode is greatly improved, and the electromechanical coupling capability is strengthened; the lower electrode is only positioned inside a cavity formed by the silicon dioxide film, the silicon strut and the silicon dioxide insulating layer, so that the lower side of the film is effectively vibrated rather than covering the whole silicon substrate, the parasitic capacitance is effectively reduced, the electromechanical conversion ratio is further increased, and the effective utilization rate of electric energy is improved.
Description
Technical field
The invention belongs to MEMS and technological field of biochemistry, particularly a kind of biochemical sensor based on CMUT and preparation method thereof.
Background technology
Biological and chemical sensor is many to be combined into by mass sensor and polymers function layer, by quality, is changed and is caused that the translation of resonant frequency realizes the detection of biological chemistry amount.Common based on MEMS(MicroElectro-Mechanical Systems, micromachine electronic system) the biochemical sensor microstructure of technology mainly contains micro-cantilever, piezoelectric quartz crystal, thin film bulk acoustic resonator, SAW (Surface Acoustic Wave) resonator, though it is very ripe that these measure structure, but because himself architectural feature has limited the raising of resonant frequency and quality factor, for example, the resonant frequency in air of conventional cantilever beam structure is tens KHz, and quality factor is less than 100; And in liquid due to the increase of damping, resonant frequency and quality factor will significantly reduce that (resonant frequency drops to tens KHz, quality factor is less than 10), thereby the biochemical sensor based on these structures is difficult to realize the detection of the biochemical substances of high sensitivity, high-resolution and less quality limit.
With respect to above micro sensing structure, just began one's study in recent years based on CMUT(CapactiveMicromachined Ultrasonic Transducer, capacitance micro-machining ultrasonic sensor) biochemical sensor in the above difficult problem, show more advantage overcoming.Have benefited from MEMS micro-processing technology and CMUT self unique texture, the less film quality that CMUT has, higher resonant frequency (can reach tens MHz) and quality factor (can reach hundreds of) determine that it can realize the more measurement of high sensitivity and less quality limit; It easily processes, easily array, the feature such as easy of integration are measured simultaneously advantage is provided for realizing the different biochemical substances of hyperchannel.At present, occurred adopting CMUTs to detect the dimethyl methyl phosphonate test of (dimethyl methylphosphonate is called for short DMMP) as biochemical sensor, it detects quality limit is 0.162 * 10
-16g, volume sensitivity is 37.38ppb/Hz; Also adopt CMUTs to detect isopropyl alcohol, acetone, alcohol and water, detecting quality limit is 10
-15g, volume sensitivity is 41.6ppb/Hz.But mostly these biochemical sensors are based on some common CMUT structures, in when work, affect because of factors such as large stray capacitance, large film quality, silicon base high impedance and isolation layer charging phenomenons, limited the further raising of detection sensitivity and quality limit, thereby these conventional CMUT inadaptability in structures can not be given full play to the many advantages of CMUT when using as biochemical sensor in other words as biochemical sensor.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of biochemical sensor based on CMUT and preparation method thereof, to avoid bottom electrode isolation layer charging phenomenon, to reduce stray capacitance and electric energy loss, further improve electromechanical coupling factor and measure sensitivity, realizing the more detection of trace toxic biochemical substances.
The present invention is based on the biochemical sensor of CMUT, comprise the first component and the second component that are bonded together up and down, described first component comprises the first monocrystalline silicon and the silica membrane layer forming in the first monocrystalline silicon upper surface oxidation, described the first monocrystalline silicon middle part is provided with cavity, this cavity runs through the first monocrystalline silicon and terminates in silica membrane layer on thickness direction, is disposed with upper electrode layer and the sensitive material layer of metal at silica membrane layer upper surface, described second component comprises silicon base and silicon dioxide insulating layer, described silicon base through-thickness is provided with through hole and groove, the two connects on its thickness direction, described silicon dioxide insulating layer is arranged on silicon base upper surface, the inside surface of lower surface and through hole and groove, on the silicon dioxide insulating layer of silicon base upper surface, be provided with bottom electrode, this bottom electrode comprises the column in the through hole that is deposited on the metal film layer of silicon dioxide insulating layer upper surface and is deposited on through-silicon upper surface of substrate, wherein, the metal film layer of described bottom electrode does not cover whole silicon dioxide insulating layer completely but covers the center section of silicon dioxide insulating layer and the center line of the metal film layer of bottom electrode and the center line of top electrode overlap, the silicon dioxide insulating layer that described first component and second component are positioned at silicon base upper surface by the remaining part of first component the first monocrystalline silicon and second component carries out bonding and forms, the lateral dimension of described metal film layer is at least half of corresponding size of effective vibration film of silica membrane layer, and is at least 1 μ m with the lateral separation of the monocrystalline silicon internal face of first component.
Described silica membrane layer thickness scope is 0.1 μ m～0.5 μ m, and effective vibration surface diameter range of silica membrane layer is 10 μ m～20 μ m;
After described the first monocrystalline silicon middle part arranges cavity, remaining part forms silicon pillar, and the width of this silicon pillar is greater than 40 μ m, is highly 2～5 μ m;
The height of described cavity is 0.5～1.2 μ m;
The thickness of the metal film layer of described bottom electrode is 1～4 μ m;
Described through hole is used to bottom electrode and the external world that electrical connecting passage is provided, and its via height is at least 40 μ m, and its through-hole diameter is 3～4 μ m;
Described top electrode covers whole silica membrane or covers the middle subregion of silica membrane;
Described silica membrane, top electrode, responsive identification material layer form vibration film jointly, and the thickness of this vibration film is less than 1.5 μ m.
The preparation method who the present invention is based on the biochemical sensor of CMUT comprises the following steps:
(1) get the first monocrystalline silicon and its upper and lower surface is oxidized respectively and forms silica membrane layer (now not oxidized monocrystalline silicon be called the first monocrystalline silicon), its lower surface silicon dioxide layer middle part of etching forms cavity graphical window, expose monocrystalline silicon, etching is exposed to the monocrystalline silicon in window and stops at its upper surface silicon dioxide layer, the silicon dioxide layer that exposes upper strata, then remove and be positioned at the residue silicon dioxide layer of the first monocrystalline silicon lower surface and its lower surface is carried out to chemically mechanical polishing, form first component; Wherein, the region that is etched in the middle part of the first monocrystalline silicon forms cavity, and remaining cavity around monocrystalline silicon partly forms monocrystalline silicon pillar;
(2) get the second monocrystalline silicon and its upper and lower surface oxidation is formed to silica membrane layer, the upper and lower silicon dioxide layer of etching makes it form respectively graphical window, expose the second monocrystalline silicon, etching is exposed to the second monocrystalline silicon in upper and lower graphical window until connect, and the region that is now etched at the second monocrystalline silicon middle part forms through hole and groove from top to bottom; Be oxidized the second monocrystalline silicon upper and lower surface and through hole and groove inside surface and form complete silicon dioxide isolation layer, chemically mechanical polishing the second monocrystalline silicon upper surface silicon dioxide insulating layer, then deposit metallic material in this silicon dioxide insulating layer upper surface and through hole, after photoetching, as bottom electrode, so far form second component;
(3) under vacuum environment, the second component that the first component that step (1) is obtained and step (2) obtain carries out bonding, wherein, first component is positioned at the top of second component, namely the silicon pillar of first component is positioned on the silicon dioxide insulating layer of second component the second monocrystalline silicon upper surface, so, the silicon dioxide insulating layer of the second monocrystalline silicon upper surface is by the cavity sealing of first component;
(4) the silica membrane upper surface at first component upper surface deposits the metal film layer as top electrode, and at metal film layer upper surface deposition sensitive material layer, finally on sensitive layer, photoetching is used for lead-in wire.
Compared with prior art, biochemical sensor that the present invention is based on CMUT and preparation method thereof at least has the following advantages:
(1) further reduce vibration film thickness (being less than 0.5 μ m) and quality, can effectively improve film resonant frequency, and then improve CMUT working sensitivity and biochemical substances detection limit.
(2) between vibration film and pillar, internal stress is less and connection reliability is higher, has effectively guaranteed mechanical property and functional reliability that film is good.
(3) with respect to the situation as bottom electrode by whole silicon base, use metallic film as bottom electrode, to increase substantially the conductive capability of bottom electrode, strengthen the electric field intensity between two electrodes, and then electromechanical coupling factor is greatly improved.
(4) on metal bottom electrode without electric isolation layer, avoided because of the impact of bottom electrode isolation layer charging phenomenon on CMUT job stability in highfield.
(5) metal bottom electrode is only positioned at the below of effective vibration film, and the impact of stray capacitance has effectively been reduced in the inside of cavity, further improves the serviceability of sensor.
(6) at the silicon base back side, form groove, reduced to be electrically connected to for bottom electrode the length of through hole, reducing difficulty of processing and in the time, also having effectively reduced series resistance value, reduce power consumption.
Accompanying drawing explanation
Fig. 1 is the structural representation that the present invention is based on the biochemical sensor of CMUT;
Fig. 2 is the flow process chart of sensor of the present invention.
Label in figure represents as follows:
| 1 | Responsive identification material layer | 2 | Silica membrane layer |
| 3 | Silicon dioxide insulating layer | 4 | Silicon base |
| 5 | Bottom electrode | 6 | Silicon pillar |
| 7 | Top electrode | 8 | Cavity |
| 9 | Through hole | 10 | Groove |
| 11 | The first monocrystalline silicon | 12 | The second monocrystalline silicon |
Embodiment
Below in conjunction with accompanying drawing, to the present invention is based on CMUT(Capacitive Micro-fabricated UltrasonicTransducer) biochemical sensor and preparation method thereof be described in detail:
Refer to shown in Fig. 1, the invention discloses a kind of biochemical sensor based on CMUT, comprise the first component and the second component that are bonded together up and down.Described first component comprises the first monocrystalline silicon, the silica membrane 2 forming in the first monocrystalline silicon upper surface oxidation, be deposited on silica membrane 2 upper surfaces and as the metal film layer of top electrode 7, be deposited on the sensitivity identification material layer 1 of metal film layer upper surface, wherein, the middle part of described the first monocrystalline silicon is etched with cavity 8, expose silica membrane 2, the first monocrystalline silicon staying forms the silicon pillar 6 with second portion bonding; Described second component comprises silicon base 4, through hole 9, groove 10, bottom electrode 5 and the whole silicon dioxide insulating layer 3 forming in silicon base 4 upper and lower surfaces, through hole 9 and groove 10 inside surface oxidations; Wherein said through hole 9 and groove 10 are symmetrical and on its thickness direction, be communicated with and run through about silicon base 4 center lines, described silicon dioxide insulating layer 3 covers silicon base 4, through hole 9 and groove 10 inside surfaces, for the isolated whole monocrystal silicon substrate 4 of electricity, described bottom electrode 5 comprises metal film layer on silicon dioxide insulating layer 3 and the column in through hole 9, and thin metal layer is positioned at cavity 8 inside.
Shown in Fig. 1, the biochemical sensor structure that the present invention is based on CMUT comprises from top to bottom successively: responsive identification material layer 1, top electrode 7, silica membrane 2, silicon pillar 6, bottom electrode 5, silicon dioxide insulating layer 3, silicon base 4.Wherein, described silicon base 4 is followed successively by bottom electrode from top to bottom and is electrically connected to through hole 9 and silicon base groove 10, and wherein, bottom electrode is electrically connected to through hole 9 and silicon base groove 10 in silicon base 4 centers, and symmetrical about silicon base 4 central shafts; Described bottom electrode is electrically connected to through hole 9 and silicon base groove 10 is communicated with and runs through on silicon base 4 thickness directions; The inside surface that described silicon base 4 upper and lower surfaces and bottom electrode are electrically connected to through hole 9 and silicon base groove 10 forms silicon dioxide isolation layer 3 through oxidation.Described bottom electrode 5 comprises that the metal film layer on silicon dioxide insulating layer 3 is electrically connected to the interior column identical with metallic film layer material of through hole 9 with bottom electrode.Described silica membrane 2, silicon pillar 6 and cavity 8 are formed through oxidation, etching by same monocrystalline silicon, silicon dioxide insulating layer 3 sealed cavities 8.Described silica membrane 2, top electrode 7 and the common vibration film that forms of responsive identification material layer 1.
Described silica membrane 2 is major parts of CMUT vibration film, for reduce film quality, improve resonant frequency as far as possible, and then increase the sensitivity that described sensor detects biochemical substances, realizing less quality limit value measures, silica membrane thickness range is 0.1 μ m～0.5 μ m, effective vibration surface diameter range of silica membrane is 10 μ m～20 μ m, and effective vibration surface diameter of described silica membrane refers to that silica membrane is positioned at lateral dimension or the width dimensions directly over cavity; In addition due on bottom electrode 5 without electric isolation layer, therefore, described silica membrane is simultaneously as the electric isolation layer between top electrode 7 and bottom electrode 5, to guarantee the security of working sensor.
Described silicon pillar 6 lateral dimensions should be greater than 40 μ m, to guarantee its holding strength, and simultaneously for reduce cavity height as far as possible, enhanced machine electric coupling coefficient, silicon pillar 6 altitude ranges are 2～5 μ m.
Described cavity 8, for increasing electromechanical coupling factor, improve sensitivity, cavity height should be as far as possible little, the height that cavity 8 significant height values equal silicon pillar 6 herein deducts bottom electrode 5 thickness, its scope is 0.5 μ m～1.2 μ m, and the significant height value of described cavity refers to the cavity height between silica membrane and bottom electrode.Silica membrane 2, silicon pillar 6 and cavity 8 successively form by oxidation, back etching on same monocrystalline silicon piece, do not adopt common thin film deposition or bonding technology, therefore between silicon pillar 6 and silica membrane 2, internal stress is less, connection reliability is higher, improves vibration of thin membrane mechanical property and functional reliability.
Bottom electrode 5 is comprised of the column of metal film layer and electrical connection on silicon dioxide insulating layer 3; Described metal film layer is for producing electric field with top electrode 7, and the column of electrical connection is for realizing metal film layer and extraneous being electrically connected to.Wherein, the thickness range of metal film layer is 1 μ m～4 μ m, thicker metallic film is conducive to reduce resistance in series on the one hand, larger film thickness scope is conducive to highly carry out reasonable combination with silicon pillar 6 on the other hand, when reducing silicon pillar 6 difficulty of processing, forms designed cavity height; The surface diameter of metal film layer is at least half of effective vibration film size of silica membrane 2, and is at least 1 μ m with the lateral separation of silicon pillar 6 internal faces.
Described electrical connection through hole 9 is used to bottom electrode 5 and the external world that electrical connecting passage is provided, and its via height is tried one's best little but is at least 40 μ m, guarantees through hole surrounding structure intensity when reducing resistance in series as far as possible; Its through-hole diameter is 3 μ m～4 μ m, is guaranteeing that low resistance in series reduces difficulty of processing simultaneously, shortens process time.
Described silicon base groove 10, on the one hand with respect to the electrical connection through hole situation that runs through whole silicon base, can significantly reduce difficulty of processing, shorten the process-cycle; Facilitate on the other hand the fixing of whole sensor and be electrically connected to.Silicon base groove 10 height are determined because being electrically connected to the height of through hole 9, and groove 10 is communicated with and runs through whole silicon base with through hole 9; Its lateral dimension meet groove with top structure intensity prerequisite under, to facilitate, be processed as suitablely, its lateral dimension is at least 4 μ m.
Described silicon dioxide insulating layer 3, its gauge is at least 2 μ m, to realize bottom electrode 5 and silicon base 4 electricity isolation completely, is beneficial to reduce stray capacitance.
Described top electrode 7 covers whole silica membrane 2, to strengthen electric field intensity, reduces pick-up voltage, and its gauge scope is 0.5～1 μ m.
Described responsive identification material layer 1, is the functional material layer of recognition detection biochemical, and different sensitive materials can be identified different biochemicals, and it is covered on top electrode 7, and thickness is less than 1 μ m.Silica membrane 2, top electrode 7, the common vibration film that forms of responsive identification material layer 1, its thickness is less than 1.5 μ m.
Silicon base 4 is that whole sensor provides support and basis.
The present invention is based on the biochemical sensor of CMUT, its main structure parameters is:
Silica membrane effective diameter: 10 μ m～20 μ m
Silicon dioxide vibration film thickness: 0.1 μ m～0.5 μ m
Top electrode thickness: 0.5 μ m～1 μ m
Bottom electrode thickness: 1 μ m～4 μ m
Vibration film gross thickness: be less than 1.5 μ m
Cavity height: 0.5～1.2 μ m
Bottom electrode is electrically connected to through-hole diameter: 3 μ m～4 μ m
The manufacturing process of a kind of biochemical sensor based on CMUT of the present invention is described below in conjunction with Fig. 2:
(1) to being positioned at the two-sided oxidation of (111) crystal face the first monocrystalline silicon 11 on the left side, strictly control oxidated layer thickness, in the upper and lower surface of (111) crystal face the first monocrystalline silicon 11, form respectively silica membrane 2; To being positioned at the two-sided oxidation of <111> crystal face the second monocrystalline silicon 12 on the right, control oxidated layer thickness, in the upper and lower surface of (111) crystal face the second monocrystalline silicon 12, form respectively silicon dioxide insulating layer 3.
(2) the silica membrane litho pattern window to first monocrystalline silicon 11 lower surfaces on the left side, and be exposed to the silicon dioxide oxide layer in window by HF solution removal, form silicon dioxide masking layer; Silicon dioxide insulating layer 3 each photoetching definite shape windows to second monocrystalline silicon 12 upper and lower surfaces on the right, and expose the silicon dioxide layer in circular window by HF solution removal, form silicon dioxide masking layer.
(3) center section that the first monocrystalline silicon 11 use wet methods on the left side or plasma etching is fallen to the first monocrystalline silicon 11 forms cavity 8, retains the part of both sides, forms silicon pillar 6; Right the second monocrystalline silicon 12 use same method etchings are formed to through hole 9 and groove 10, wherein, part second monocrystalline silicon 12 of through hole 9 for etching away the silicon dioxide insulating layer 3 of the second monocrystalline silicon 12 upper surfaces and being adjacent, described groove 10 is for downward until run through the silicon dioxide insulating layer of the second monocrystalline silicon 12 lower surfaces from through hole 9 lower limbs.
(4) use the silica membrane of first monocrystalline silicon 11 lower surfaces on the HF solution removal left side, and carry out chemical machinery and cut open light, form first; The second monocrystalline silicon to the right is further oxidized, in the second monocrystalline silicon one end adjacent with through hole and the second monocrystalline silicon one end adjacent with groove be further oxidized formation silicon dioxide insulating layer.
(5) with LPCVD technology plated metal in silicon dioxide insulating layer 3 upper surfaces of the second monocrystalline silicon upper surface and through hole 9 on the right, form bottom electrode 5, this bottom electrode 5 comprises the metallic film that is arranged in silicon dioxide insulating layer upper surface and the column that is deposited on through hole.
(6) both sides of the metallic film part of electrode 5 are fallen down in photoetching, and the silicon dioxide layer 3 exposing is carried out to topochemistry mechanical buffing, form second portion.
(7) under vacuum environment, the first that step (4) is formed carries out anode linkage with the second portion of step (6) formation, and wherein, first is upper, second portion under, the second monocrystalline silicon of second portion forms the silicon base of whole sensor.
(8) at the silica membrane upper surface of first's upper surface, use LPCVD deposition techniques as the metal film layer of top electrode 7, at metal film layer upper surface, adopt LPCVD deposition techniques sensitive material layer 1, finally on sensitive material layer 1, photoetching is used for lead-in wire.
The shape of described cavity 8 can circle, rectangle, square or other polygon, and specifically applicable cases is selected suitable shape; Described electrical connection through hole 9 and silicon base groove 10 are circular, also can be other shape, take and easily process, are applicable to concrete applicable cases as principle of design.The size of silicon pillar 6, bottom electrode 5, cavity 8 should consider, and makes the height of formed cavity 8 minimum as far as possible.The material of top electrode 7 and bottom electrode 5 can be identical, also can be different, can suitably select according to functional requirement, cost etc., and top electrode 7 can cover whole silica membrane 2, certainly, also can only cover the middle subregion of silica membrane 2, metallic film can form the top electrode of various shape and size after depositing on silica membrane 2 and covering completely by photoetching, will make in a word the serviceability of CMUT optimum.Responsive identification material layer 1 can be applied corresponding sensitive material according to the biochemical substances of required detection.In addition, the biochemical sensor that the present invention is based on CMUT is a sensor unit, be that a plurality of sensing units form array format in actual applications, sensor unit quantity and formed array format can be according to functional requirement, fabrication process condition, cost designed, designeds, general this design is comparatively simple, ripe, no longer discusses herein.In addition, during application, also should consider to design last encapsulating structure, to prevent the impacts such as corrosion of biochemical substances on sensor.Finally, corresponding to different working temperatures, the impact of the hot expansibility that should consider lower metal electrode on sensor cavities height, accurately determines the operating voltage of this temperature lower sensor, to realize the accurate measurement to detected material.
The key technical indexes of the present invention is as follows:
Measuring media: micro biochemical material
Volume sensitivity: be better than 50ppb/Hz
Quality limit value: be better than 10
-18g
Response time: be less than 15min
Measuring accuracy: be better than 8%FS
Working temperature :-20 ℃-150 ℃
A kind of biochemical sensor based on CMUT of the present invention can effectively improve biochemical substances detection sensitivity, realizes more micro biochemical material and detects; Avoid bottom electrode electricity isolation layer charging phenomenon in the conventional biochemical sensor work based on CMUT, improve working sensor stability; Adopt metal electrode as bottom electrode, and by metal electrode layer and silicon base electricity isolation completely, replace the way using silicon base as bottom electrode in the conventional biochemical sensor based on CMUT, increase substantially the electric field intensity between upper and lower two electrodes, enhanced machine electric coupling ability; Bottom electrode is only positioned at cavity inside, the below of effective vibration film, but not cover whole silicon base, and effectively reduce stray capacitance, further increase dynamo-electric transformation ratio, improved the effective rate of utilization of electric energy.
The foregoing is only one embodiment of the present invention, it not whole or unique embodiment, the conversion of any equivalence that those of ordinary skills take technical solution of the present invention by reading instructions of the present invention, is claim of the present invention and contains.
Claims (9)
1. the biochemical sensor based on CMUT, it is characterized in that: comprise the first component and the second component that are bonded together up and down, described first component comprises the first monocrystalline silicon and the silica membrane layer (2) forming in the first monocrystalline silicon upper surface oxidation, described the first monocrystalline silicon middle part is provided with cavity (8), this cavity runs through the first monocrystalline silicon and terminates in silica membrane layer on thickness direction, is disposed with upper electrode layer (7) and the sensitive material layer (1) of metal at silica membrane layer (2) upper surface; described second component comprises silicon base (4) and silicon dioxide insulating layer (3), described silicon base through-thickness is provided with through hole (9) and groove (10), the two connects on its thickness direction, described silicon dioxide insulating layer (3) is arranged on silicon base (4) upper surface, the inside surface of lower surface and through hole and groove, on the silicon dioxide insulating layer (3) of silicon base upper surface, be provided with bottom electrode (5), this bottom electrode (5) comprises the column in the through hole that is deposited on the metal film layer of silicon dioxide insulating layer (3) upper surface and is deposited on through-silicon upper surface of substrate, wherein, the metal film layer of described bottom electrode (5) does not cover whole silicon dioxide insulating layer completely but covers the center section of silicon dioxide insulating layer and the center line of the metal film layer of bottom electrode and the center line of top electrode overlap, the silicon dioxide insulating layer that described first component and second component are positioned at silicon base upper surface by the remaining part of first component the first monocrystalline silicon and second component carries out bonding and forms, the lateral dimension of described metal film layer is at least half of corresponding size of effective vibration film of silica membrane layer (2), and is at least 1 μ m with the lateral separation of the first monocrystalline silicon internal face of first component.
2. the biochemical sensor based on CMUT as claimed in claim 1, is characterized in that: described silica membrane layer (2) thickness range is 0.1 μ m～0.5 μ m, and effective vibration surface diameter range of silica membrane layer is 10 μ m～20 μ m.
3. the biochemical sensor based on CMUT as claimed in claim 1, is characterized in that: after described the first monocrystalline silicon middle part arranges cavity (8), remaining part forms silicon pillar (6), and the width of this silicon pillar (6) is greater than 40 μ m, is highly 2～5 μ m.
4. the biochemical sensor based on CMUT as claimed in claim 1, is characterized in that: the height of described cavity (8) is 0.5～1.2 μ m.
5. the biochemical sensor based on CMUT according to claim 1: it is characterized in that: the thickness of the metal film layer of described bottom electrode (5) is 1～4 μ m.
6. the biochemical sensor based on CMUT according to claim 1: it is characterized in that: described through hole (9) is used to bottom electrode (5) and the external world that electrical connecting passage is provided, and its via height is at least 40 μ m, its through-hole diameter is 3～4 μ m.
7. the biochemical sensor based on CMUT according to claim 1: it is characterized in that: described top electrode covers whole silica membrane or covers the subregion in the middle of silica membrane.
8. the biochemical sensor based on CMUT according to claim 1: it is characterized in that: described silica membrane (2), top electrode (7), responsive identification material layer (1) form vibration film jointly, and the thickness of this vibration film is less than 1.5 μ m.
9. a preparation method for the biochemical sensor based on CMUT, is characterized in that: comprise the following steps:
(1) get the first monocrystalline silicon and its upper and lower surface is oxidized respectively and forms silica membrane layer, its lower surface of etching, silica membrane layer middle part forms cavity graphical window, expose monocrystalline silicon, etching is exposed to the monocrystalline silicon in window and stops at its upper surface silicon dioxide layer, the silica membrane layer that exposes upper strata, then removes and is positioned at the residue silica membrane layer of the first monocrystalline silicon lower surface and its lower surface is carried out to chemically mechanical polishing, forms first component; Wherein, the region that is etched in the middle part of the first monocrystalline silicon forms cavity, and remaining cavity around monocrystalline silicon partly forms monocrystalline silicon pillar;
(2) get the second monocrystalline silicon and its upper and lower surface oxidation is formed to silica membrane layer, the upper and lower silica membrane layer of etching makes it form respectively graphical window, expose the second monocrystalline silicon, etching is exposed to the second monocrystalline silicon in upper and lower graphical window until connect, and the region that is now etched at the second monocrystalline silicon middle part forms through hole and groove from top to bottom; Be oxidized the second monocrystalline silicon upper and lower surface and through hole and groove inside surface and form complete silicon dioxide insulating layer, chemically mechanical polishing the second monocrystalline silicon upper surface silicon dioxide insulating layer, then deposit metallic material in this silicon dioxide insulating layer upper surface and through hole, after photoetching, as bottom electrode, so far form second component;
(3) under vacuum environment, the second component that the first component that step (1) is obtained and step (2) obtain carries out bonding, wherein, first component is positioned at the top of second component, namely the silicon pillar of first component (6) is positioned on the silicon dioxide insulating layer of second component the second monocrystalline silicon upper surface, so, the silicon dioxide insulating layer of the second monocrystalline silicon upper surface is by the cavity sealing of first component;
(4) the silica membrane upper surface at first component upper surface deposits the metal film layer as top electrode (7), and at metal film layer upper surface deposition sensitive material layer (1), finally on sensitive layer, photoetching is used for lead-in wire.
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| CN108348217B (en) * | 2015-11-02 | 2021-07-20 | 皇家飞利浦有限公司 | Ultrasound transducer array, probe and system |
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