CN105264338A

CN105264338A - Ultrasonic sensor microarray and its method of manufacture

Info

Publication number: CN105264338A
Application number: CN201480015015.3A
Authority: CN
Inventors: 萨扎杜尔·乔杜雷
Original assignee: University of Windsor
Current assignee: University of Windsor
Priority date: 2013-03-14
Filing date: 2014-03-12
Publication date: 2016-01-20
Also published as: EP2972112A1; JP2016516184A

Abstract

A sensor assembly includes one or more capacitive micromachined ultrasonic transducer (CMUT) microarray modules which are provided with a number of individual transducers. The microarray modules are arranged to simulate or orient individual transducers in a hyperbolic paraboloid geometry. The transducers/sensor are arranged in a rectangular or square matrix and are activatable individually, selectively or collectively to emit and received reflected beam signals at a frequency of between about 100 to 170 kHz.

Description

Ultrasonic sensor microarray and its manufacture method

Related application

The application is that the part of U.S. Patent Application Serial Number 13/804279 submitted on March 14th, 2013 continues case.

The international patent application serial number PCT/CA2013/000937 owned together that the name that the application relates on November 01st, 2013 and submits to is called " UltrasonicSensorMicroarrayandMethodofManufacturingSame (ultrasonic sensor microarray and its manufacture method) ", and the mode quoted in full is incorporated herein.

Technical field

The present invention relates to a kind of micro mechanical system (MEMS) and its manufacture method, and the three-dimensional MEMS device that can serve as the parts of capacitance type micromachined ultrasonic wave transducer (CMUT) is more specifically as sensor microarray.In a kind of advantageous applications, the present invention relates to a kind of ultrasonic sensor microarray and its manufacture method, it comprises or simulates the configuration of hyperbolic paraboloidal sensor or chip, and it comprises benzocyclobutene (BCB) as structure member.The Suitable applications of CMUT comprises medical treatment and other non-vehicle application, and for the application of vehicle or automobile sensor purposes, such as, drive in the monitoring of vehicle blind spot, barrier and/or at autonomous vehicle and/or stop in application.

Background technology

In publication DesignofaMEMSDiscretizedHyperbolicParaboloidGeometryUltr asonicSensorMicroarray (design of MEMS discretize hyperbolic paraboloid geometry ultrasonic sensor microarray), IEEETransactionsOnUltrasonics, Ferroelectrics, AndFrequencyControl (IEEE ultrasonics, ferroelectrics and frequency control transactions), 55th volume, 6th phase, in in June, 2008 (by reference its disclosure being incorporated to herein at this), the present inventor describes the concept of the discretize hyperbolic paraboloid geometric configuration Wave beam forming array of capacitance type micromachined ultrasonic wave transducer (CMUT), described array group is contained on the layering geometry of micro-manufacture.

In the initial manufacture concept of CMUT, silicon-on-insulator (SOI) wafer is tentatively cleaned, then use rf magnetron sputtering to deposit the chromium kind crystal layer of 10nm thereon to provide bonding coat.After the described chromium bonding coat of deposition, use the conventional thick layer gold of CMUT deposition 200nm.After deposition thereof, by AZ4620 photoresist thin layer rotating and depositing (spin-deposite) in described layer gold, carry out patterning and etching.Then by described wafer is immersed in liquor kalii iodide, then in rare chloroazotic acid, chromium kind crystal layer etched and carry out thereafter flushing to etch layer gold.Thereafter be etched with device layer further and provide acoustical ports, described acoustical ports is used for the static pressure balance in barrier film and allows to remove SiO in release stage (releasestage) ₂.

In inductively coupled plasma reactive ion etching machine (ICP-RIE), use Bosch process (Boschprocess) deep reactive ion etch (DRIE) to etch top SOI wafer.Etching utilizing Bosch and DRIE after carrying out metal etch, passing through O ₂remaining photoresist is removed in ashing process.The wafer that Bosch etches is immersed in buffer oxide etch (BOE) solution optionally to etch SiO when significantly not etching monocrystalline silicon ₂discharge selectivity barrier film.In etching with after rinsing, the sensitive surface (dyestuff) of each array is carried out assembling and is used electroconductive binder epoxy resin to bond in system level chip manufacture.

But the applicant understands, the existing technique for the manufacture of capacitance type micromachined ultrasonic wave transducer needs accurate manufacturing tolerance.As a result, the manufacture on a commercial scale of the array of CMUT sensor or transducer is not yet popularized in the market widely.

By reference the U.S. Patent No. 6942750 of its Chou be incorporated herein in full etc. is described structure (construct) and the method for the patterned wafers using photosensitive benzocyclobutene (BCB) to bond in the manufacture of 3DMEMS structure.Especially, Chou etc. disclose and use the photosensitive BCB of photoactivation as the assembly bonding agent for realizing precise patterning wafer bonding, add the Z height of assembled wafers complex by the gained three-dimensional MEMS microstructure that BCB bonding coat realizes simultaneously.

Summary of the invention

The present inventor understands, by improve manufacture method and/or utilize adjustable frequency of operation can realize novel and/or more reliable CMUT Array Design.A non-limiting object of the present invention is for providing a kind of ultrasonic sensor, it comprises for sending and one or more CMUT microarray of Received signal strength or module, and it may more by one or more the impact in the ultrasonic background noise source of number of different types, and described noise source is such as road noise, pedestrian, cyclist and/or animal traffic, car crass sound, industrial operation, energy source etc.

In a kind of structure, the invention provides a kind of three-dimensional MEMS device and be more preferably CMUT transducer, it comprises silicon-based wafer, as benzocyclobutene (BCB) resin of the structure member in Z axis as Cyclotene ^tM, and silicon and/or BCB base barrier film or membrane layer.

Another kind of non-limiting structure provides a kind of microarray based on ultrasound wave CMUT, and it provides programmable bandwidth to control, and it allows more easily to revise CMUT microarray design for multiple different sensor application.

Another kind of non-limiting structure provides a kind of ultrasonic sensor, it comprises and has substantially flat curvature, preferably have be less than ± 10 ° and be more preferably less than transducer microarray module or the sub-component of the curvature of about ± 1 °, and its simulation hyperbolic paraboloidal chip array geometric configuration in operation.

An embodiment of the invention provide a kind of microarray module based on capacitance type micromachined ultrasonic wave transducer (CMUT) comprising multiple transducer.Described microarray module is suitable for vehicle, and non-vehicle track, aircraft and other sensor application.Such as, described module can be provided as a part for hand or body position sensor, and in the alarm for monitoring blind spot, adjacent barrier and hidden danger and/or control system, and/or in the alarm of road vehicle position and/or autonomous driving application.

Another embodiment of the invention provides a kind of microarray for the manufacture of the transducer/sensor based on CMUT and more preferably based on the method for the microarray module of CMUT, described microarray module being operable to transmit in multiple frequency and/or frequency range, and it can be arranged to the frequency interferences from adjacent sensors is minimized.In a kind of possible preferable production process, conventional (i.e. non-photosensitivity) benzocyclobutene (BCB) is as Cyclotcne ^tMbonding coat is used as in the formation of the microarray as die/wafer configuration.In a kind of possible structure, BCB is further used for forming interchangeable transducer diaphragm or barrier film.

It is contemplated that, a kind of manufacture simulation hyperbolic parabola geometric configuration or the possible simplification of CMUT microarray module provided with hyperbolic parabola geometric configuration and reliable method can use molded, punching press or three-dimensional (3D) Method of printing be formed in above backing or the substrate of the microarray of transducer module are installed.In addition, by changing orientation (orientation) or the operation of independent CMUT microarray module in sensor array, optionally selecting preferred or variable beamformer output shape is provided.

In another non-limiting embodiment, the invention provides a kind of sensor module, it is provided with one or more capacitance type micromachined ultrasonic wave transducer (CMUT) microarray module, and described module installation has multiple independent transducer.In a non-limiting final sensor construction, arrange make independent transducer simulation or be orientated common hyperbolic paraboloid geometric configuration to CMUT microarray module.But other module arrangement and geometric configuration are possible.

Preferably, described sensor module comprises at least one CMUT microarray module, and described module comprises multiple independent transducer/sensor, and described transducer/sensor can individually, optionally or jointly activate to transmit and receive reflected signal.In order to make transmission disturbance minimize, in each module, most preferably arrange transducer/sensor with rectangular matrix, and transducer/sensor can be selectively activated simultaneously.More preferably, multiple microarray is set in each sensor module.Described microarray usually with 3 × 3 or more square or rectangular matrix arrange and install, and wherein each microarray module contains at least 36 and preferred at least 200 independent ultrasonic transducer/sensors.Although optional, in a kind of simplified design, sensor microarray module physical is positioned on three-dimensional backing, forms described three-dimensional backing with directed microarray module and provide sensor array with discretize, usually hyperbolic paraboloid shape.When being provided in automobile application, selecting the hyperbolic paraboloid of described module directed, making transducer/working sensor to export the preferred wave beam visual field between 15 ° and 40 ° and preferably between about 20 ° and 25 °.

Described sensor transducer can work under the suitable frequency scope being low to moderate 40kHz.In vehicle application, more preferably, the transducer/sensor for each microarray of discrete actuation can operate air-damped effect is minimized under the frequency of at least 100kHz and most preferably from about 150kHz.In a preferred structure, when providing sensor module for during as vehicle blind spot working sensor, described sensor module is formed to have compact sensor design, it is characterized in that:

Package size PGA68stickleadmount

Update rate 50 to 100 milliseconds and preferably about 80 milliseconds

Array distribution at least 3 × 3; And preferably 5 × 5 hyperbolic paraboloids or larger

Wave beam visual field 15 to 170 degree or larger; And 25 to 140 degree are preferably for automobile

Frequency range 50 to 200kHz; And preferably 100 to 170kHz

Sensing range target 3.5 to 7 meters; And preferably about 5.0 meters

Should be understood that in other applications, the microarray module and beam angle with different number and/or the sensor containing the more different size of the CMUT microarray module of the independent transducer/sensor of big figure can be provided.Depend on application, consider integral sensors size of components, desired use and device requirements, the number of independent transducer/sensor may exceed thousands of or tens thousand of.

In another embodiment, microarray module is installed to backing, and described backing substantially goes up flat geometry and it preferably has and is less than ± the curvature of 10 ° and be more preferably less than ± 1 °.Although sensor module can comprise few to a microarray module, more preferably provide multiple CMUT microarray module, and its with 5 × 5 or larger square matrices module arrangement arrange.Optionally, the form of the usual flexible sheets that free form can be allowed to be shaped forms independent CMUT microarray module, to allow wider beamformer output shape and/or configuration.

Each microarray module self be preferably provided with at least 5 × 5 and preferably 40 × 40 or more the sensor array of independent CMUT transducer/sensor.Transducer/sensor in each microarray module itself electricity can also be subdivided into two or more grouping.In a simplified design, the transducer of each microarray module is directed and electricity is subdivided into multiple parallel row and/or row with rectangular matrix.But other segmentation arranges it is possible, comprise independent transducer/sensor electrical isolation for discrete actuation.Microarray transducer is subdivided into parallel column or row and divides into groups to allow independent transducer/sensor group to be optionally coupled (couple) to frequency generator and by group activation.More preferably, described sensor module is able to programme with the grouping of the transducer/sensor optionally activated or in inactive each CMUT microarray module.

In another embodiment, can be configured optionally activate independently of one another to the microarray module in each sensor module.By this way, the applicant understands, and according to application and/or environment, dynamically can realize the change of sensor module beam angle, shape and/or emission wavelength.More preferably, make CMUT microarray module be suitable for electronics and export the wave beam with multiple different beams shape, length and/or profile (profile).

In a kind of preferred operation mode, optionally electric power switching is realized to the various combination of the transducer grouping in each module or row.The applicant understands, and by such switching, therefore can change the output shape of the transmission signal launched by sensor module, such as, will output signal better from sensor module guiding associated target areas.By this way, according to application (i.e. environment, car speed, type of drive (forward and counter motion) and/or sensor applications), can be configured to beamformer output geometric configuration the rub-out signal avoided from other vehicle or external source; Or to be provided within the scope of frequency or beam angle changeable beamformer output to detect dissimilar barrier.

In a preferred operator scheme, electric power is optionally supplied to each independent CMUT microarray module in sensor array column matrix.By this way, independent module can be activated to realize flight time object detection and/or to obtain position.In addition, the selectivity of independent CMUT microarray module and the wherein grouping of transducer/sensor controls and activates the three-dimensional wave beam shaping advantageously allowing broad range, to allow wider sensor application or demand.

In a kind of possible structure, provide Microprocessor S3C44B0X.Described Microprocessor S3C44B0X drives switch unit and unit frequency generator.More preferably, Microprocessor S3C44B0X drives switch unit and generator to realize the computerize sequence of the combination of the columns and rows of the transducer in each CMUT microarray module, and changes shape, the frequency of sensor module output signal with predetermined sequence or scope.By this way, the interference from other automobile sensor that may be close to and false readings can be distinguished or minimize further.

In final design, the activated silica wafer components of silicon wafer is used as the diaphragm of each CMUT transducer, base wafer forms bottom silicon layer simultaneously.The structural sheet of the BCB of main binding agent is used as to come bond substrates and silicon top wafer.At 150 DEG C, preferably carry out bonding process to drive away any residual solvent and to have allowed maximum bonded intensity.Then by the sample of bonding solidification about 1 hour in the nitrogen environment at 250 DEG C.

Therefore, provide multiple non-limiting aspect of the present invention, and it comprises:

A kind of method formed for having the capacitance type micromachined ultrasonic wave transducer (CMUT) in the microarray of multiple transducer, described method comprises: provide first silicon-based wafer usually with smooth upper surface and lower surface, be provided as the second wafer of device layer, described device layer has usually smooth parallel top surface and basal surface, described device layer has and is chosen as about 0.05 to 5 micron and is preferably the thickness of about 0.2 to 1 micron, benzocyclobutene (BCB) layer is formed on one in the described top surface or described basal surface of described device layer, the etched surfaces that formation wherein has multiple depression is etched with to the surface of described bcb layer, each in described depression has preselected geometry, the feature of described depression is that respective sidewall extends to about 0.1 to 15 micron, preferably about 0.2 to 8 micron and the most preferably from about degree of depth of 3 to 4 microns, and another in the described top surface of a part for the etched surfaces of described bcb layer and described device layer or described basal surface is alignd, utilize the described bcb layer inserted therebetween by described first wafer bonding extremely described device layer, described depression forms respective transducer air gap thus, conducting metal is applied at least one in described first wafer and described second wafer.

A kind of method formed for comprising the condenser type micro Process transducer in the microarray of multiple transducer, described method comprises: provide the silicon backing wafer usually with smooth parallel front surface and rear surface, described backing wafer has the thickness being chosen as about 10 to 500 microns, benzocyclobutene (BCB) structural sheet is formed on described front surface, described structural sheet has and is chosen as about 0.5 to 15 micron and preferably about 1 to 10 micron and the thickness of most preferably 3 to micron, light plasma etch is carried out to form multiple depression wherein to the surface of described BCB structural sheet, described depression has usually common geometric configuration and is characterised in that respective sidewall usually extends perpendicular to described front surface and extends to the degree of depth of about 0.1 to 10 micron, there is provided and there is usually smooth parallel opposed front face and the device layer of rear surface, described device layer has and is chosen as about 0.05 to 10 micron, be preferably about 0.2 to 2 micron and most preferably be the thickness being less than 1 micron, be arranged as and substantially continuously the described rear surface of described device wafer be bonded on described front surface substantially to seal each depression as respective transducer air gap, and wherein utilize the described BCB structural sheet as structure bond composition to be bondd relative to described first wafer by described device wafer, conductive metal layer is applied in described first wafer and described device wafer at least one at least partially.

A kind of for sending and/or the ultrasonic transducer system of receiving sensor wave beam, described system comprises frequency generator and sensor module, described sensor module comprises backing, multiple capacitance type micromachined ultrasonic wave transducer (CMUT) microarray module, described microarray module on described backing with grid matrix orientation arrangement, each described microarray comprises multiple transducers with transducer air gap and diaphragm element, and described microarray module comprises: have usually smooth top surface and the bottom silicon layer of basal surface; there is usually benzocyclobutene (BCB) structural sheet of parallel flat front and rear surface, extend rearward to the multiple depressions in the described front surface of described BCB structural sheet, described each depression limits the side of corresponding transducer air gap and bottom and directed and have and be chosen as about 0.2 to 5 micron with array separately, preferably 3 to 4 microns the degree of depth and be chosen as 5 to 200 microns and the preferred width of 10 to 50 microns, with the device layer with front surface and rear surface, described device layer has and is chosen as about 0.1 to 25 micron and the thickness being preferably less than 1 micron, described BCB structural sheet inserts between the bottom of described device layer and the described top surface of described bottom silicon layer, described device layer is as each described depression of corresponding transducer diaphragm component sealing simultaneously, it is one or more that at least one first conductive member is electrically connected in described transducer diaphragm component, at least one second conductive member inserts between the rear surface of described backing and described bottom silicon layer, at least one first conductive member described can be electrically connected to ground wire or described frequency generator.

Method according to any one in aforementioned aspect and/or sensing system, wherein said bcb layer comprises the BCB structural sheet with the thickness being greater than about 0.2 micron and described device layer comprises silicon-based devices layer.

Method according to any one in aforementioned aspect and/or sensing system, wherein said bcb layer comprises BCB device layer, and described BCB device layer comprises BCB base device layer.

Method according to any one in aforementioned aspect and/or sensing system, the described upper surface that wherein said forming step is included in described first wafer forms described BCB structural sheet; With before described adhesion step, maintain described device layer as substantially uncured BCB base device layer.

To described BCB structural sheet, method according to any one in aforementioned aspect and/or sensing system, wherein before described etching step, carry out that described BCB is partially cured to about 30% to 70% of complete solid state.

Method according to any one in aforementioned aspect and/or sensing system, wherein said adhesion step comprises described BCB structural sheet is heated to complete solid state, and the BCB in wherein said BCB structural sheet by described first wafer bonding to described device layer.

Method according to any one in aforementioned aspect and/or sensing system, wherein said etching step comprises light plasma etch.

Method according to any one in aforementioned aspect and/or sensing system, wherein after bonding, the first bondd wafer is become independent microarray with described device wafer physical segmentation, that described microarray comprises 9 × 9 transducers or larger square matrices.

Method according to any one in aforementioned aspect and/or sensing system, it comprises the described lower surface of described top surface or described first wafer conductive metal layer being applied to described device layer at least partially further, described metal is selected from gold, silver and copper, and wherein said conductive metal layer has and is chosen as about 1 to 500 nanometer and is preferably the thickness of about 5 to 50 nanometers.

Method according to any one in aforementioned aspect and/or sensing system, wherein said geometric configuration comprise have be chosen as about 5 to 100 microns and be preferably the width of about 10 to 40 microns and the usual square shape of length lateral dimension.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein forming described depression comprises and forms described depression with usual square matrices, and the grouping of wherein said depression is with multiple parallel row and/or column alignment.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein applying described conductive metal layer comprises and being coated with the whole top surface of described device wafer substantially, and wherein after coating, optionally remove a part for described conductive metal layer to divide into groups described at least some of described depression and adjacent packets electric isolution.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein applying described conductive metal layer comprises: before bonding, the through hole through described first wafer is formed in the respective respective bottom areas of described depression, and form conducting metal pad in corresponding bottom section, wherein said conductive pad provides the electric connection (electricalcommunication) with the described lower surface of described first wafer by described through hole.

Method according to any one in aforementioned aspect and/or sensing system, 13 comprise further and the grouping of described depression being exported to realize stronger signal with can operate to be electrically connected with the changeover module optionally divided into groups described in electric coupling.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein forming described BCB structural sheet comprises with about 1 to 50 micron substantially, preferably about 2 to 5 microns, and most preferably BCB is applied to the described upper surface of described first wafer by the thickness of 3 to 4 microns.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein forming described depression comprises formation at least one hundred depressions and the quadrate array of preferred at least five hundred depressions, and each described depression has usually smooth bottom section.

Method according to any one in aforementioned aspect and/or sensing system, in addition wherein before described etching, described second wafer is mounted to bearing wafer, and described second wafer is ground and/or laser ablation has the described device layer of the thickness of expectation to be formed.

Method according to any one in aforementioned aspect and/or sensing system, wherein before the described BCB structural sheet of formation, adhesion promotor coating is applied at least one in described upper surface and lower surface, and described adhesion promotor coating has the thickness being chosen as and being less than about 50nm.

Method according to any one in aforementioned aspect and/or sensing system, wherein said device wafer comprises silicon-based devices layer.

Method according to any one in aforementioned aspect and/or sensing system, wherein said device wafer comprises BCB base device layer.

Method according to any one in aforementioned aspect and/or sensing system, the described front surface that wherein said forming step is included in described first wafer forms described BCB structural sheet; With before described adhesion step, maintain described device layer as usually uncured BCB base device layer.

Method according to any one in aforementioned aspect and/or sensing system, wherein before described etching step, to heat described BCB structural sheet with described BCB is partly cured to complete solid state about 30% to 70% and preferably about 50%.

Method according to any one in aforementioned aspect and/or sensing system, wherein said adhesion step comprises described BCB structural sheet is heated to complete solid state, and the BCB in wherein said BCB structural sheet by described first wafer bonding to described device wafer.

Method according to any one in aforementioned aspect and/or sensing system, wherein said etching step comprises and carries out light plasma etch to described BCB structural sheet.

Method according to any one in aforementioned aspect and/or sensing system, wherein after bonding, become independent microarray with described device wafer physical segmentation, that described microarray comprises at least 9 × 9 transducers or larger matrix by the first wafer of bonding.

Method according to any one in aforementioned aspect and/or sensing system, it comprises the rear front surface of described front surface or described first wafer described conductiving metal coating being applied to described device wafer at least partially further, described metallic coating is selected from gold, silver, copper and its alloy, and wherein said conductive metal layer has and is chosen as about 1 to 500 nanometer and the thickness of preferred about 5 to 50 nanometers.

Method according to any one in aforementioned aspect and/or sensing system, wherein said geometric configuration comprises having and is chosen as about 5 to 200 microns and the preferred usual square shape of lateral dimension of 10 to 40 microns.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein applying described conducting metal comprises and being coated with the whole front surface of described device wafer substantially, and wherein after coating, optionally remove a part for described conductiving metal coating to divide into groups described at least some of described depression and adjacent packets electric isolution.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein applying described conductiving metal coating comprises: before bonding, the through hole through described first wafer is formed in the respective respective bottom areas of described depression, and form conductive pad in corresponding bottom section, wherein said conductive pad provides the electric connection with the described lower surface of described first wafer by described through hole.

Method according to any one in aforementioned aspect and/or sensing system, it comprises further and the grouping of described depression being electrically connected with the changeover module optionally described grouping being electrically coupled to frequency generator with can operate.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein forming described BCB structural sheet comprise BCB is applied to described first wafer described front surface as substantially parallel layer, it has and is chosen as about 1 to 100 micron and preferably about 2 to 25 microns and the most preferably thickness of 3 to 4 microns.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein forming described depression comprises formation at least one hundred depressions and the quadrate array of preferred at least five hundred depressions, and each described depression has usually smooth bottom.

Method according to any one in aforementioned aspect and/or sensing system, in addition wherein before described etching, be mounted to bearing wafer by described device wafer, and by the thickness that described device wafer device layer grinds and/or laser ablation is extremely expected.

Method according to any one in aforementioned aspect and/or sensing system, wherein before the described BCB structural sheet of formation, adhesion promotor coating is applied at least one in the described front surface of described first wafer and the rear surface of described device wafer, described adhesion promotor coating has the thickness being chosen as and being less than about 50nm, and wherein selects described adhesion promotor coating with the described BCB structural sheet that bonds.

Method according to any one in aforementioned aspect and/or sensing system, it comprises further provides sensor backing platform, described backing platform comprises the usual square mounting surface with the width being chosen as about 0.5 to 10cm, after bonding, first wafer of described bonding and device layer are divided into multiple CMUT transducer microarray module comprising multiple transducer, each microarray module has common geometric configuration and has the mean breadth of about 1mm to 2mm, the transducer microarray module of selection is arranged in described mounting surface.

Method according to any one in aforementioned aspect and/or sensing system, wherein said installation steps comprise, with usual quadrate array, described CMUT transducer microarray module are mounted to described backing platform.

Method according to any one in aforementioned aspect and/or sensing system, it comprises further and forms described backing platform by the ABS with usual smooth module mount surface.

Method according to any one in aforementioned aspect and/or sensing system, it comprises the described backing platform being formed and have discretize hyperbolic paraboloid mounting surface further, described hyperbolic paraboloid mounting surface comprises multiple discrete flat surfaces of corresponding for receiving above in described microarray module, and to be arranged in described discrete flat surfaces on corresponding one further by one selected in described CMUT transducer microarray module.

Method according to any one in aforementioned aspect and/or sensing system, the step wherein applying described conductive metal layer comprises the metal level that sputtering is selected from gold, silver and copper, and wherein said first conductive metal layer has and is chosen as about 100 to 500 nanometers and the thickness of preferred about 100 nanometers.

Method according to any one in aforementioned aspect and/or sensing system, the described step wherein etching described depression comprises carries out plasma etching with the array of usual square or rectangular matrix to described depression, and the described transducer wherein in each microarray module aligns with multiple parallel row and column.

Method according to any one in aforementioned aspect and/or sensing system, wherein said device layer comprises to have and is chosen as about 0.2 to 5 micron and the silicon base layer being preferably less than the thickness of 1 micron.

Method according to any one in aforementioned aspect and/or sensing system, wherein said device layer comprises to have and is chosen as about 0.2 to 5 micron and the bcb layer being preferably less than the thickness of 1 micron.

Method according to any one in aforementioned aspect and/or sensing system, wherein said BCB structural sheet has and is chosen as about 1 micron of to 40 microns and preferably thickness of about 3 microns to 4 microns, and wherein said BCB structural sheet has the thickness of at least half degree of depth being chosen as described depression between adjacent described air gap.

Method according to any one in aforementioned aspect and/or sensing system, wherein said depression comprises with the usual square depression of usual square matrices array orientation.

Method according to any one in aforementioned aspect and/or sensing system, it comprises the adhesion promotor coating between at least one in the part and described bottom silicon layer and described device layer inserting described BCB structural sheet further.

Method according to any one in aforementioned aspect and/or sensing system, it comprises multiple described first conductive member, described first conductive member, described first conductive member is electrically connected the respective packets of the described transducer diaphragm component in each CMUT microarray separately, and comprise further and can activate optionally to connect the one or more changeover module in described frequency generator and described first conductive member, optionally to activate the respective packets of transducer.

Method according to any one in aforementioned aspect and/or sensing system, wherein said first conductive member and each self-contained conductiving metal coating of described second conductive member.

Method according to any one in aforementioned aspect and/or sensing system, wherein each described grouping comprises the column grouping of described transducer.

Method according to any one in aforementioned aspect and/or sensing system, wherein said array comprises at least 25 depressions, preferably at least 100 depressions and the usual quadrate array of more preferably at least 400 depressions.

Method according to any one in aforementioned aspect and/or sensing system, wherein said sensor module comprises programmable vehicle parking and assists or blind-spot sensors.

Method according to any one in aforementioned aspect and/or sensing system, the sensor wave beam wherein sent has and is chosen as 50 to 200kHz and the frequency of preferred about 150 to 163kHz.

Method according to any one in aforementioned aspect and/or sensing system, wherein for sending and/or the ultrasonic transducer system of receiving sensor wave beam, described system comprises frequency generator and sensor module, described sensor module comprises multiple capacitance type micromachined ultrasonic wave transducer (CMUT) microarray module, described microarray module aligns with usual matrix, each described microarray module comprises multiple condenser type micro Process transducer with transducer air gap and diaphragm element, described condenser type micro Process transducer is formed by described method, and wherein said microarray module comprises: the bottom silicon layer with usual planar top surface, to be arranged on described top surface and there is the BCB structural sheet of the multiple square depression formed wherein, described each depression limit the side of corresponding described transducer air gap and bottom separately and with usual quadrate array directed and have be chosen as about 0.2 to 10 micron and preferably 3 to 4 microns the degree of depth and be chosen as 5 to 100 microns and the preferred width of 10 to 40 microns, with the top device layer covering described BCB structural sheet, described device layer seals each described depression as corresponding described transducer diaphragm component and has the thickness being chosen as about 0.1 to 5 micron, with at least one conductive member, it extends and can be electrically connected to ground wire or described frequency generator in the part of one of described diaphragm element.

Method according to any one in aforementioned aspect and/or sensing system, it comprises multiple described conductive member, described conductive member is electrically connected the grouping of the multiple described transducer in each CMUT microarray, and its work is to produce the output frequency of more wide region.

Method according to any one in aforementioned aspect and/or sensing system, it comprises multiple described conductive member, and described conductive member is electrically connected the corresponding described transducer in each CMUT microarray individually.

Method according to any one in aforementioned aspect and/or sensing system, wherein said quadrate array comprises at least 25 depressions and the array of preferred at least 400 depressions.

Method according to any one in aforementioned aspect and/or sensing system, wherein said sensor wave beam has and is chosen as 50 to 200kHz and the frequency of preferred about 150 to 163kHz.

Method according to any one in aforementioned aspect and/or sensing system, wherein said device layer comprises silicon wafer, and described silicon wafer has and is chosen as about 0.2 to 4 micron and the thickness being preferably less than 1 micron.

Method according to any one in aforementioned aspect and/or sensing system, wherein said device layer is made up of bcb layer substantially, and described bcb layer has and is chosen as about 0.2 to 4 micron and the thickness being preferably less than 1 micron.

Accompanying drawing explanation

Can by reference to the accompanying drawings together with reference to detailed description below, wherein:

Fig. 1 schematically shows automobile, and it illustrates the ultrasonic sensor assembly layout wherein based on CMUT, and its overlay area expected, as a part for the vehicle safety monitoring system for monitor vehicle blind spot;

Fig. 2 illustrates ultrasonic sensor assembly according to first embodiment of the invention, and it comprises 5 × 5 structures for the CMUT microarray module in the monitoring system of Fig. 1;

Fig. 3 illustrates that the wave beam of 5 × 5 structures of the CMUT microarray module shown in Fig. 2 exports the polar plot of geometric configuration;

Fig. 4 illustrates the sensor backing platform about 5 × 5 structures, and its display is used for 25 CMUT microarray module height close to continuous print hyperbolic paraboloid surface;

Fig. 5 provides the amplification cross-sectional view for the independent CMUT transducer in the ultrasonic sensor CMUT microarray module shown in Fig. 2 manufactured according to first;

Fig. 6 schematically shows the ultrasonic sensor assembly of 5 × 5 array structures according to another implementation of the invention with 25 CMUT microarray modules;

Fig. 7 is illustrated schematically in the enlarged drawing of the independent CMUT microarray module used in the array of ultrasonic sensors of Fig. 6;

Fig. 8 a, 8b and 8c illustrate that wave beam selected by the output signal from the ultrasonic sensor assembly shown in Fig. 6 exports the polar plot of geometric configuration;

Fig. 9 schematically shows the operation of the independent transducer/sensor of the CMUT microarray module shown in Fig. 7;

Figure 10 is illustrated schematically in the partial cross section view of the amplification of the transducer/sensor used in CMUT microarray module shown in Fig. 7;

Figure 11 schematically shows according to the first manufacturing mode and the silicon backing wafer forming the processing layer that uses in transducer Lower Half preform and be coupled;

Figure 12 is illustrated schematically in initial applying BCB structural sheet on the bottom silicon backing die/wafer configuration shown in Figure 11;

The BCB structural sheet that Figure 13 is illustrated schematically in the applying shown in Figure 12 applies the photic resist layer in top;

Figure 14 is illustrated schematically in the part of the photoresist oxidant layer shown in Figure 13 before bcb layer etches and removes;

Figure 15 schematically shows the partially-etched of the bcb layer shown in Figure 14, and the follow-up applying of adhesion promoter layer;

Figure 16 schematically shows according to the formation of the first manufacture method for the formation of the silicon wafer first half preform of transducer diaphragm barrier film;

Figure 17 illustrates the partial enlarged drawing on first half preform to be arranged in the final assembly of transducer by display Lower Half preform according to the first method for optimizing;

Figure 18 schematically shows according to an alternative method, the initial applying on the silicon wafer that adhesion promoter layer uses in Lower Half preform is formed;

Figure 19 schematically shows the applying in BCB structure adhesion promoter layer shown in Figure 18;

Figure 20 schematically shows the applying of the photic resist layer in top on the BCB structural sheet of the applying shown in Figure 19;

The part of the photoresist oxidant layer that Figure 21 is shown in Figure 20 before being illustrated schematically in etching bcb layer is removed;

Figure 22 is illustrated schematically in be etched with depression and removes the BCB that exposes and the Lower Half preform optionally after adhesion promoter layer;

Figure 23 is illustrated schematically in the Lower Half preform shown in Figure 22 after removing remaining photic resist layer;

Figure 24 is illustrated schematically in the formation of the first half preform used in the manufacture according to the transducer of an alternate embodiments, the applying of initial conduction gold sedimentary deposit on silicon holding clamp;

Figure 25 schematically shows the applying on conductive layer that adhesion promoter layer formed in fig 23;

Figure 26 schematically shows the formation in BCB barrier film adhesion promoter layer shown in fig. 25;

Figure 27 is illustrated schematically in the assembling according to first half preform during other method manufacture transducer and Lower Half preform;

Figure 28 schematically shows the transducer/sensor manufactured according to alternative method;

Figure 29 schematically shows transducer/sensor according to another implementation of the invention;

Figure 30 illustrates and in silicon wafer, forms through hole according to another embodiment, to manufacture bottom preform;

Figure 31 illustrates after the gold of through hole is filled, the applying of photoresist oxidant layer on the silicon wafer of Figure 30;

Figure 32 illustrates after the activation of photoresist oxidant layer, gold deposition and washing, conductive gold pad and the formation of sensor wire on the silicon wafer of Figure 31; With

Figure 33 schematically shows according to another embodiment, the formation of conductive gold pad on the preform of bottom.

Embodiment

(i) 5 × 5 array

Can with reference to figure 1, it schematically shows the vehicle 10 had based on hyperacoustic barrier monitoring system 12 according to the first embodiment.Monitoring system 12 comprises a series of ultrasonic sensor assembly 14a, 14b, 14c; they can operate to transmit and receive ultrasonic beam signal separately in corresponding vehicle blind spot or relevant range 8a, 8b, 8c; to detect adjacent vehicle and/or neighbouring barrier, or the intrusion in institute protection zone.

Each sensor module 14 is shown as the array comprising 25 identical capacitance type micromachined ultrasonic wave transducer (CMUT) microarray modules 16 in fig. 2 best.As will be described, microarray module 16 is installed on three-dimensional substrates or backing platform 18, and the inner concave or surperficial 19 of microarray module 16 is orientated common hyperbolic paraboloid geometric configuration simultaneously.Fig. 2 illustrates each CMUT microarray module 16 best, it is again formed by 36 independent CMUT transducer/sensors 20 (hereafter also referred to as transducer), and it exports in operation and receives the ultrasonic signal wave beam (Fig. 3) usually extended.In one embodiment, transducer 20 is positioned in 6 × 6 in independent microarray module 16 (not in scale show) rectangle or square matrices or grid arrangement.

Fig. 4 illustrates three-dimensional backing platform 18 best, has a lot of module mount surface 24 as being built as, and described mounting surface 24 is relative to each other with selected level L ₁, L ₂... L _nbe positioned in the common hyperbolic parabolic shape of discretize, this shape is chosen to be the usual continuous print of simulation and bends hyperbolic paraboloid curvature.In the version simplified, backing platform 18 is formed as three-dimensional plastic or silicon backing, and it presents the smooth square mounting surface 24 of 25 discrete.In this regard, can to use by plastics and three-dimensional chip 36 assembled by the backing platform 18 that more preferably acrylonitrile-butadiene-styrene (ABS) (ABS) is formed, described backing platform 18 forms shape by means of 3D printing process.In a substituting production method, 3D chip backing platform 18 is formed via micro injection molding method by injection moulding.Each mounting surface 24 has coplanar structure and passes through suitable (complimentary) size selected to receive and to support corresponding CMUT microarray module 16 thereon.By this way, CMUT microarray module 16 itself be arranged on three-dimensional backing platform 18, the convex geometry of mounting surface 24 makes the array of microarray 16 be orientated the hyperbolic paraboloid geometry of the common discretize of expectation simultaneously.

In a kind of possible structure, when providing backing platform 18 for rear ground connection CMUT microarray module 16, described backing platform 18 is provided with gold or the copper top coat 50 of electric conductivity, and described top coat 50 serves as the conventional ground plane of each module transducer 20.Golden electricity is bonded to suitable needle connector 32 (Fig. 2) again by described back sheet 18, and it is for installing pin substrate 34 as the sensor chip 36 used in each sensor module 14a, 14b, 14c.In the mill, use sputtering, plating, electroless plating/coating, plasma to be coated with and/or other method for metallising, the backing platform 18 of three-dimensional surface (and preferably being formed by ABS plastic) to the discretize formation with expectation is coated with suitable deposition of conductive metals coating 50.Metal sedimentation model is selected to the stepless control layer making it possible to settle conducting metal on the end face of formed ABS plastic backing platform 18.Described conductiving metal coating 50 is selected to the earth conductor of the side of the transducer 20 be provided in each microarray module 16.Preferred plated metal comprises the metal of copper, gold, silver, aluminium or other high connductivity.

After this settle each CMUT microarray module 16 and be directly bonded to in the corresponding mounting surface 24 of conductiving metal coating 50 electrical contact of backing platform 18 with electroconductive binder, using needle connector 32 that backing platform 18 is mounted to pin substrate 34 simultaneously.Should be understood that when backing platform 18 is for top ground module 16, top coat 50 can be omitted, and suitable transducer connecter trace can be provided to provide the electrical connection with module transducer 20.In an alternative design, single substrate can be provided, its completely by conducting metal as copper or gold are made.

The applicant understands, and by changing the curvature simulated by the relative positioning of mounting surface 24 in different hyperbolic paraboloid configures, can change the beamformer output geometric configuration of sensor chip 36, to make the application of its adaptive expectation.Such as, use sensor module 14 in support vehicle sensors 14c time (Fig. 1), described backing platform 18 can have more flat hyperbolic paraboloid curvature through selecting to produce relatively wider, shorter beam signal.By contrast, sensor module 14a, 14b can be provided with the backing platform 18 with more higher curvature degree relatively, to export narrower, longer beam signal.

In a kind of structure simplified most, 6 × 6 arrays of the independent transducer 20 in each CMUT microarray module 16 present usually smooth front surface 19 (Fig. 2), and it serves as the signal projector/receiver surface for generated ultrasonic signal.In use, independent transducer 20 electronically activates to launch, and then receives the ultrasonic beam signal reflected by neighbouring vehicle and/or barrier.By this way, launch according to signal, reflection with receive between sequential and/or the intensity of the ultrasonic signal of reflection that detected by each microarray module 16, monitoring system 12 can be used for providing barrier alarm, or when automatic Pilot is applied, control running velocity and/or direction.

As shown best in Fig. 3, time in applying for vehicle, independent CMUT microarray module 16 can operate to send and the beam signal of receive frequency under about 113 ~ 167kHz scope simultaneously.In the rainy day or have in mist environment, most preferably module 16 is with the signal frequency operation of about 150kHz ± 13, and beam angle is 20 ± 5 °, and wherein maximum side lobe intensity is-6 decibels.Sensor microarray module 16 can when without provide when any microelectric signals process have nothing to do with frequency broad-band EDFA.

In the structure of each ultrasonic sensor assembly 14, each CMUT microarray module 16 used in monitoring system 12 is preferably formed to has about 1 to 5mm ²footprint area (footprintarea) and the height of about 0.5 to 2mm.In fig. 2 shown in 5 × 5 matrix arrangements in, sensor chip 36 therefore with 25 36 microarraies grouping mode, at seven discrete elevation levels L _1-7(Fig. 4) transducer 20 that under, in 5 × 5 matrix distribution, accommodation 900 is independent.

Fig. 5 is best shown in the cross-sectional view of the amplification of the independent rear portion ground connection transducer 20 existed in each CMUT microarray module 16 according to first embodiment of the invention manufactured.Transducer 20 is provided with usual foursquare central air cavity or air gap 42.Transducer 20 has separately and is chosen as about 20 to 50 μm and the preferred average square transverse width dimension d of about 30 μm _{on average}, simultaneously internal air gap 42 on vertical Z direction of principal axis with the height h of about 60% to 80% of the transverse width of transducer 20 _gextend.Transducer 20 comprises as the top conductive gold conductive layer 48 of main structural components, interchangeable silicon device layer or diaphragm membrane 44, silicon bottom layer or wafer 46, with benzocyclobutene (BCB) layer 54 of centre, described benzocyclobutene layer 54 provides as structural sheet and limits the lateral dimension of air gap 42, and is formed with thickness (in the Z-axis direction) to provide the air gap height h of expectation _g.Therefore the lower limit of air gap 42 is limited by silicon bottom layer 46, and or may may not be provided with adhesion promotor coating 56 as AP3000 according to manufacture ^tMto promote bcb layer 54 and its bonding.Air gap 42 has the height h being chosen as about 800 to 1000nm and being more preferably about 900nm _g.Diaphragm membrane 44 covers air gap 42, and preferably has 0.5 to 1 μm and the thickness of preferred about 0.8 μm, but also can use thicker or thinner diaphragm membrane.

In a kind of manufacturing mode, the diaphragm membrane 44 by electro-deposition golden conductive layer 48 being coated on the transducer 20 in each microarray module 16 forms the front surface 38 of each transducer 20.Select to make not disturb barrier film 44 to move to the thickness of conductive layer 48 and preferably it is chosen as about 0.1 to 0.2 μm.In addition, bottom conductive coating 50 can directly provide along the silicon bottom wafer of each transducer 20 or the rear surface 22 of layer 46, or can as previously mentioned pre-applied in each mounting surface 24 of backing platform 18.By this way, by the conductive coating 50 on the top conductive layer 48 of each microarray module 16 and backing platform 18 is electrically coupled to frequency generator (being shown as 70 in fig .9), the barrier film 44 of transducer 20 can be activated to launch and/or receive and sense produced ultrasonic signal.

As by described in a kind of possible manufacture method, the microarray module 16 of transducer 20 can use the manufacture of silicon-on-insulator (SOI) technology, has the independent component halves of the three-dimensional backing platform 18 formed by silicon for preform.Module 16 and backing platform 18 are assembled and is encapsulated in programmable gain amplifier PGA-68 and pack in 71 (Fig. 9).The present invention also provides a kind of manufacture more simplified method that three-dimensional hyperbolic paraboloid chip 36 constructs, and more preferably wherein said hyperbolic paraboloid chip 36 plays a role together with the capacitance type micromachined ultrasonic wave transducer of hyperbolic paraboloid geometric configuration.

Simplify in structure in one, the front surface 38 of the transducer 20 in each microarray module 16 provides usually smooth surface.But the present invention is not restricted to this.In a kind of alternative structure, the front surface 38 of each microarray module 16 can be provided with curvature or adapt to curvature.In this arrangement, the own direct-assembling of transducer 20 in each CMUT microarray module 16 is on bottom that is flexible and that can compile or backing substrate (not shown).This backing substrate is selected from a kind of material and has certain thickness and bends or bending to allow microarray module 16, and with compared with the step surface close to this free form surface, 3D hyperbolic paraboloid surface realistic is better as continuous print free form surface.Preferred flexible backing for microarray module 16 can comprise monolithic silicon wafer 80 (Figure 11), and it is for the formation of self having the back sheet 46 that is less than about 5 μm and is preferably less than each module 20 of the thickness of 1 μm and by Cylothane ^tMor the independent or alternative back sheet that benzocyclobutene (BCB) is made.This free form surface is also molded advantageously allowing the flexible backings of each CMUT microarray module 16 to be directly placed in free form on backing platform 18, makes sensor chip 36 have the more accurate approximate value of actual hyperbolic paraboloid configuration of surface.

The present inventor has realized that the opereating specification susceptible of proof of CMUT microarray module 16 has the importance of increase when being used as vehicle monitoring system 12 a part of.Although optional, preferably, in order to design concrete scope, measure the range attenuation of air at particular point of operation place and attenuation by absorption.The damping of air damping (air resistance) the theory calculate sound that usual known use is following:

P _{sPL damping}=-20log ₁₀(R ₁/ R ₂)

Wherein for SPL standardization object, R ₁30cm, and R ₂the ultimate range reached.For the distance of 5m, ultrasound wave should be advanced 10m.The damping obtained in 10m distance of solving an equation is-30 decibels.In addition, the following absorption of air calculated because humidity causes:

α(f)＝0.022f-0.6dB/ft

Wherein α is the absorption of air because frequency f causes.For worst-case, humidity is taken as 100%.Within the scope of 10m after being transformed by ft, for 150kHz, this absorption value is calculated as-53 decibels.

Therefore it should be understood that when total value, the remarkable damping of-83 decibels may be there is.By contrast, the applicant has realized that if transducer 20 operates in 60kHz, then total damping and absorption will be-51 decibels, and this is by stronger for the ultrasonic signal allowing to receive.

In the structure of Fig. 2, after acquisition total damping and absorption value, correspondingly design independent transducer 20.Especially, because total damping value adds up to-83 decibels, therefore CMUT transducer 20 is most preferably designed to have very high output pressure, and the most optionally 100 dB sound pressure levels (SPL) or larger.Have realized that preferably, the diaphragm membrane 44 (Fig. 5) of CMUT transducer 20 being less than 20 μm through selecting to have, being preferably less than 5 μm and the most preferably from about thickness (T of 1 μm _d) (Fig. 5).Selected diaphragm size allows diaphragm membrane 44 to have the large distance for vibrating, and lower DC operating voltage.

In addition Mason theory is followed (see DesignofaMEMSDiscretizedHyperbolicParaboloidGeometryUltr asonicSensorMicroarray (design of MEMS discretize hyperbolic paraboloid geometry ultrasonic sensor microarray), IEEETransactionsOnUltrasonics, Ferroelectrics, andFrequencyControl (IEEE ultrasonics, ferroelectrics and frequency control transactions), 55th volume, 6th phase, in August, 2008, its disclosure is incorporated to by reference at this), in automobile sensor application, each CMUT transducer 20 is designed to operate in the frequency range of 110 to 163kHz, sensor module 14 has 25 microarray modules 16 according to specification shown in table 1 simultaneously.Most preferred frequency of operation is selected at about 150kHz ± 13, and 5 × 5 Array Designs of CMUT microarray module 16 have 40 ° of-3 dB bandwidth and the secondary lobe lower than-10 decibels simultaneously, as shown in Figure 3.At this on the one hand, acoustic pressure can be obtained by following equation:

P _α＝Re(Z _m)ωA _α

Wherein A _αbe sonic wave amplitude, it equals the displacement of CMUT diaphragm, and ω is the angular frequency of barrier film and Z _mit is the sound radiation impedance of the diaphragm obtained from Mason method mentioned above.

Table 1-CMUT sensor array specification-automobile sensor

Parameter	Value
		Module array	5×5
Array-3 decibels of beam angles (°)	40°
		The sensor length of side (mm)	15.75
CMUT microarray module side (mm)	1.6～1.8
		CMUT transducer diaphragm material	Low-resistivity polysilicon
The CMUT transducer length of side (mm)	0.25～0.3
		CMUT transducer diaphragm thickness (μm)	0.5～1.0
CMUT transducer resonance frequency (kHz)	150(±13)
		CMUT transducer air gap (μm)	2.5～4
Array pressure exports (dB sound pressure level)	102.5
		CMUT bias voltage (V _DC)	40
CMUT pick-up voltage (V _DC)	51
		CMUT receiving sensitivity (mV/Pa)	60
The signal (mV) received under 10m	2

Upper table 1 outlines as backup sensors to provide the sensor array specification of the prototype automobile sensor of barrier alarm signal.

Fig. 6 illustrates ultrasonic sensor assembly 14 according to another implementation of the invention, and wherein same Reference numeral is for identifying same parts.In figure 6, ultrasonic sensor assembly 14 is provided with 5 × 5 quadrate arrays of 25 CMUT microarray modules 16.Each CMUT microarray module 16 is formed as again square 40 × 40 matrix (illustrating not in scale) of 1600 independent transducers 20.Although Fig. 6 illustrates the sensor module 14 comprised with 25 CMUT microarray modules 16 of 5 × 5 matrix configuration layouts, more accurate manufacturing process allows exploitation to have the sensor module of the microarray module 16 of more big figure.Therefore, different directed less or more transducer 20 can be provided.Such configuration will include but not limited to rectangular strip, be generally the geometry of circle and/or module or amorphous grouping; And with the grouping of 49 or 54 CMUT microarray modules 16 that 7 × 7,9 × 9,10 × 10 or other arranged in squares are installed.

In a kind of possible embodiment, 40 × 40CMUT microarray module 16 is fixed to ABS backing platform 18, described backing platform has and geometric configuration similar shown in Fig. 4, and flat mounting surface 24 discretize of with about 2 × 2mm and preferred 1.7 × 1.7mm.In such an embodiment, backing platform 18 is formed as approximate hyperbolic paraboloid surface in the manner described above.

In a kind of alternate design, backing platform 18 is made with and is less than about ± 10 °, is preferably less than about ± 1 ° and be more preferably less than ± substantially smooth ABS the structure of the hyperbolic paraboloid curvature of 0.5 °, and the one or more transducers 20 wherein in each CMUT microarray module 16 are exercisable closer to simulate its installation in hyperbolic paraboloid geometric configuration.In a kind of structure, microarray module 16 powers at its rear side surface 22 and is bonded to conductiving metal coating 50, and described conductiving metal coating is bonded as the metal level be deposited on ABS backing platform 18 in mode as described above.Simplify in structure in one, top metal conductive layer 48 as shown in Figure 5 is provided for second other power conductors of CMUT transducer 20, allows each microarray 16 to send and receiving mode operation.In an alternate design, conductive ground layer 50 can be applied to the front surface 38 of each microarray module 16 on barrier film 44, replaces conductive layer 48 or replaces with the layer 48 serving as ground connection.In this configuration, conductive metal layer or contact pad can be included on the rear surface 22 of bottom layer 46, or more preferably in independent transducer cavity 42, and it is electrically coupled to frequency generator 70 to send and Received signal strength.Or the transducer 20 of each module 16 discrete packets or independent mode can be electrically connected to frequency generator 70 for operating individually or in the mode of selectivity grouping.

Fig. 7 illustrates following embodiment, and wherein each 40 × 40 microarray modules 16 have square structure that the length of side (sidewidth) is about 1 to 3mm and containing 1600 transducers 20 of having an appointment.As shown best in the figure 7, in each microarray module 16, transducer 20 is arranged in the mode of the square matrices orientation of parallel row and column.Be shown as best in the cross-sectional view of transducer 20 at Figure 10 used in the module 16 of Fig. 7 to have and be chosen as about 0.02 to 0.05mm and the average transverse width dimensions d of more preferably from about 0.03mm _{on average}.Each transducer 20 limits respective rectangle air gap 42 (Figure 10), and it has up to 3nm and the height h of preferred about 2.5 to 4 μm _g, and be chosen as the width of about 0.01 to 0.03mm in the horizontal.Figure 10 illustrates that transducer 20 has the simplification structure comprising silicon bottom layer 46 further best, and it is by the Cyclotene of 0.5 to 20 μm ^tMthick-layer 104 or other suitable benzocyclobutene (BCB) resin bed 54 be fixed to top silicon diaphragm diaphragm 44.In shown array module 16, diaphragm membrane 44 has the thickness being chosen as about 0.5nm to 1.0nm.Fig. 7 illustrates that golden conductive top layer 48 is divided into conductive gold lines bonding (bonding) (W of independent electric isolution ₁, W ₂... W _n).Lines bonding W ₁, W ₂... W _nextend through the diaphragm membrane 44 of transducer 20 pairs of justifications and be optionally electrically connected to frequency generator 70 separately by commutation circuit 72.

In assembly, each 40 × 40 microarray modules 16 are arranged as the discrete unit in substantially smooth substrate or back sheet 18.In each 40 × 40 microarray modules 16 separately, transducer 20 is divided into parallel bar or row S ₁, S ₂... S ₄₀(Fig. 7).Often arrange S ₁, S ₂... S ₄₀in transducer 20 by covering corresponding conduction gold thread bonding W ₁, W ₂, W ₃... W ₄₀be electrically connected to each other.As shown in Figure 7, gold thread bonding W ₁, W ₂, W ₃... W ₄₀nominal frequencies generator 70 is optionally electrically coupled to again by commutation circuit 72 and microprocessor controller 74.Frequency generator 70 is exercisable optionally to provide electric signal or the pulse of pre-selected frequency.The applicant understands, the row S of each independent or selection of the transducer 20 in each microarray 16 ₁, S ₂... S ₄₀activation can by the output wavelength of sensor module 14 change about the factor.By activating commutation circuit 72 with optionally to the row S of the transducer 20 in each microarray module 16 ₁, S ₂... S ₄₀various combination switch energising and power-off, the signal shape of transmission signal wavelength exported from sensor module 14 can be changed.

Therefore each electric pulse produced by frequency generator 70 can be used for one or more selected arranging S by changeover module 72 what be electrically connected with each transducer 20 ₁, S ₂... S ₄₀the physical displacement of the diaphragm membrane 44 of each transducer 20 of interior impact, with about sensor module 14 operator scheme produce expect output ultrasonic wave frequency and/or profile.The applicant understands, and in most preferred arrangement, signal is with 110kHz to 163kHz and be preferably the wavelength of about 150kHz and export from sensor module 14.By the independent row S to the transducer 20 in each microarray module 16 ₁, S ₂... S ₄₀optionally activate and deactivation, the width and/or the frequency that control beamformer output can be required according to the application-specific for sensing system 12.

Such as, Fig. 8 a to Fig. 8 c illustrates, according to application requirement or the pattern of vehicle operating, independent transducer 20 in each microarray module 16 of alternative activation is to export wave beam that is wider or that even disperse, wherein such as, sensor module 14 for providing alarm signal in low speed standby assistance application.In addition, different transducers 20 combination in identical sensor module 14 can be activated to provide narrower longer beam angle, wherein such as, steering vehicle under certain speed, and sensor module 14 carries out running such as overtaking other vehicles or providing blind spot alarm during lane change.

In a most preferred operator scheme, controller 74 is used to control commutation circuit 72 activates the transducer 20 in each CMUT microarray module 16 simultaneously row S with the run duration at sensor module 14 ₁, S ₂... S ₄₀same sequence.This can advantageously make any unfavorable node impact between the signal that exported by the independent CMUT microarray module 16 in sensor and/or signal disturbing minimize.Such as, Fig. 8 a illustrates that beamformer output configures, and wherein module 16 is run under all changeover modules 72 switch to closedown.Fig. 8 b and Fig. 8 c illustrates beamformer output geometric configuration, and wherein assembly 72 is opened respectively in twice switching of each opposing end portions and four switchings.

In another kind of operator scheme, microprocessor controller 74 can be used for activating commutation circuit 72 thus drives the row S of transducer 20 with predetermined select progressively ₁, S ₂... S ₄₀to export the signal of different frequency.In another kind of pattern, controller 74 can be used for activating changeover module 72 to be enabled in one or more row S separately of the special transducer 20 in the microarray module 16 of unique selection in 5 × 5 arrays ₁, S ₂... S _n.In this respect, the differentiation that the signal exported by sensor module 14 can be encoded or sort more easily allow third party's sensor signal within the scope of certain frequency, thus the minimizing possibility making cross-point sensor interference or false alarm.

It is contemplated that, dynamic by using controller 74 and commutation circuit 72 to change sensor output wavelength, therefore the sensor module 14 shown in Fig. 7 advantageously allows beam angle able to programme to be selected as 20 to 140 ° or larger.Although Fig. 7 illustrates that the transducer 20 in each CMUT microarray module 16 is divided into 40 and independently arranges S ₁, S ₂... S ₄₀, but should be appreciated that, in alternative arrangements, the transducer 20 in each microarray 16 can be divided into groups and/or is controlled independently alternatively further.In one non-limiting embodiment, transducer 20 can be divided into groups further and is electrically connected by row, and the independent columns and/or rows simultaneously in each CMUT microarray module 16 is optionally driven by controller 74, commutation circuit 72 and frequency generator 70.

Figure 10 describes the cross-sectional view of adjacent CMUT transducer 20, and it measures about 30 × 30 microns in each horizontal direction d is average.In a preferred structure, complete CMUT microarray 16 will comprise 40 × 40 square matrices of 1600 CMUT transducers 20, and have the dimension width of about 1.7mm × 1.7mm.In a kind of alternative structure, 9 × 9CMUT chip 36 can be provided with roughly 57600 independent CMUT transducers 20.

Described sensor design provides the CMUT microarray 16 (Fig. 6) with square configuration, simultaneously sensor chip 36 has the size of each limit about 7 to 10mm, and it is processed to smooth or substantially have ± the slight hyperbolic curve of 0.5 ° of curvature.Preliminary test shows, ultrasonic sensor assembly 14 can operate to send and Received signal strength through the solid plastic bumper material of thickness up to several millimeters, and without the need to having " button " or the gatherer that exist at present.Thus, sensor module 14 can " be arranged on after bumper " advantageously in automotive vehicles applications, uses ganoid bumper fascia, produces outward appearance more attractive in appearance.

In operation, in receiving mode (schematically showing in fig .9), all or selected CMUT transducer 20 is preferably activated to receive and return beam signal extremely exports simultaneously.Thus the beam intensity of received signal and/or reaction time are used for determining obstacle distance.In a receive mode, each CMUT microarray module 16 entirety is by impacting Received signal strength, and this causes transducer diaphragm diaphragm 44 defect to produce receiver signal (receptorsignal).The intensity of the return signal detected by the defect degree of each diaphragm membrane 44 and flight time provide the instruction of the distance about adjacent barrier and/or vehicle.

Transducer manufactures

In one manufacturing approach, benzocyclobutene (BCB) is provided as structure member and/or bonding agent, described bonding agent be used in the manufacture of each microarray module 16 with silicon and the bonding of silicon-on-insulator (SOI) wafer or the bonding of silicon and silicon-on-insulator (SOI) wafer.Especially, in the first manufacturing mode, by the preformed single transducer half portion 98,100 (Figure 17) being formed as wafer sheet material being bonded together and forming transducer sheet material to form multiple CMUT microarray module 16 simultaneously, there are nearly 1600 or more CMUT transducers 20 separately.After bonding, then from formed wafer sheet configuration, wafer is cut into the independent individual module 16 with desired size.

The main manufacturing mode carrying out a kind of simplification of each 40 × 40 microarray modules 16 with bi-component manufacture method.In the mill, by using the BCB resin bed 54 of etching and preferably silicon wafer back sheet 80 (Figure 11) to be engaged to and to serve as second of device layer 84 and cover top wafer (Figure 16) and prepare microarray module 16, to provide the air gap 42 height h of expectation in z-direction by Cyclotene _gor thickness.

In one embodiment, wafer back lining 80 serves as the bottom layer 46 of each independent transducer 20.Equally, after cutting, top layers or wafer 84 serve as replaceable barrier film 44.In the preferred described method of one, optionally can be applied to silicon wafer back sheet 80 with the BCB resin bed 54 of sym-trimethyl benzene part of dilution, then be etched with and form independent depression 82, it, assembling and being connected half portion preform (preformhalf) 98,100 rear (Figure 13, Figure 16), forms independent transducer air gap 42.Should be appreciated that, utilize method of the present invention, in an alternative arrangements, BCB resin bed 54 can be applied to top layers 84, and microarray module 16 is with upside down manufacture simultaneously.

The formation of Lower Half preform 98 is described more fully best with reference to figures 11 to Figure 15.As shown best in Figure 11, by means of silicon dioxide layer 122, wafer back lining 80 is fixed to removable silicon retaining sheet 120 (illustrating not in scale), the solubilized bonding agent of silicon dioxide layer 122 as being coated on silicon retaining sheet 120 is provided simultaneously.

As shown in Figure 11, in the formation of the first half portion preform 98, provide wafer back lining 80, and removable silicon retaining sheet 120.By soluble bonding agent 122 if silica-coating is on silicon retaining sheet 120.Then wafer 80 fixed and be installed on it, then sizing.Simplify in structure in one, from preform, wafer 80 is machined to the final thickness of expectation by grinding or laser ablation.

Although preferably processed or laser ablation is to the thickness expected for layer 80, in alternative structure, described layer can rotate from other suitable material or resin and be formed.

Although optional, silicon fixing layer 120 (omitting from Figure 12 to Figure 14 for clarity) allows more easily to process wafer back lining 80, and its final sizing is to provide each transducer 20 of the bottom layer 46 of the thickness with expectation.In preferred structure, silicon backing wafer 80 is provided with the thickness being chosen as about 0.1 to 1mm in z-direction.But, thinner or thicker wafer can be used.Preferably, provide 4 inches of N-type silicon wafers 80 as back sheet wafer (Figure 14).Antimony is mixed in a large number to realize at 0.008 to 0.02 Ω cm to silicon wafer 80 ²resistance in scope.

Then by adhesion promoter layer 106 (Figure 12) as AP3000 ^tMbe applied to the top surface 108 of silicon backing wafer 80.In order to the surface be coated with for the preparation of BCB, adhesion promoter layer 106 be applied to the top surface 108 (Figure 14) of silicon wafer 80 and be then spin-dried for.Then resultant layer surface 106 is prepared immediately to be used for BCB coating to form structural sheet 54.Applying adhesion promoter layer 106 after, apply bcb layer 54 and then preferred consolidation to complete solid state about 30% to 70%.Most preferably, bcb layer 54 is selected to be Cyclotene ^tMresin, it has 30 microns and most preferably be the thickness of about 0.1 to 5 micron at the most in the Z-axis direction.Bcb layer 54 provides various advantage.Especially, bcb layer 54 is used to serve as electrical isolation (non-conductive) structural sheet.In addition, the applicant understands, and bcb layer 54 advantageously allows some to be out of shape, and make it possible to has more tolerant coordinating with silicon backing wafer 80 and wafer 84 in final assembling.This advantageously allows again the more high productivity with more consistent results.

Substitute in manufacture in one, bcb layer 54 can be fully cured, particularly when applying other bonding coat and/or adhesion promoter layer (i.e. AP3000) subsequently to it.But, most preferably, by considering the thickness of Z-direction layer, heating within the only about half of time that the time rating of expectation is solidified in realization completely, bcb layer 54 being cured to the complete solid state of about 50%.After the solidification of the expectation of bcb layer 54, photoresist coating 110 is used to shelter half portion preform 98 (Figure 13).After BCB coating, by 0.5 micron thickness Shipley1805 photoresist oxidant layer 110 (Figure 15) rotating and depositing on the top of BCB structural sheet 54.By after soft for photoresist baking at 150 DEG C, photoresist oxidant layer 110 is made to be exposed to ultraviolet light to realize photoetching and with the part of the expectation of the position of the depression 82 that will be formed and geometric configuration removing layer 110, to expose bcb layer 54 below.Apply pattern that mask coating 110 configures with the air pocket 82 (Figure 15) making bcb layer 54 and have expectation to realize desired size and the orientation of gained transducer air gap array 42.

After exposure and activation, the disactivation nubbin of the part of mask coating 110 is removed (Figure 14) to expose selected air pocket configuration and bcb layer 54 for light plasma etch.Preferably, then in ICP (inductively coupled plasma) reactor, CF is used ₄/ O ₂dry-etching is carried out to bcb layer 54 thus forms depression 82 with the pattern configured at the transducer air gap 42 being included in the expectation in microarray module 16 and orientation.Subsequently half portion preform 98 is etched with and forms independent depression groove 82 (being shown in Figure 15).Again, depression 82 be formed as tool have the dimensions and the space expected to serve as the air gap 42 of each transducer.Most preferably, depression 82 is preferably formed to and transversely has the width of about 0.03mm and the degree of depth of 2.5 to 5 microns each.

Although optional, preferably each depression 82 further extends through bcb layer 54 at least to arrive adhesion promoter layer 106 below.Optionally, can carry out being etched with the stick portion removed and promote below oxidant layer 106, thus expose silicon backing wafer 80 in the bottom of each depression 82.

Can manufacture there is square shape depression 82 to maximize its number and the layout on silicon backing wafer 80.But other embodiment can comprise circular detents or groove, produce large ship and/or the depression of polygon and/or hexagonal shape.Forming depression 82 with square matrices orientation allows the transducer of simplification to switch, but other configuration is also possible.

After the etching, clean to remove any remaining mask coating 110 to preform 98, thus expose bcb layer 54.

Figure 16 and Figure 17 illustrates the formation of best first half preform 100, and its location on bottom preform 98.Figure 17 illustrates the top silicon wafer 84 of the part being provided as SOI silicon cover wafers, and wherein said wafer 84 is releasably secured to fixing layer 124 to simplify manufacture.Fixing layer 124 can be selected from another silicon layer, and it is for installing silicon wafer 84 by soluble silicon oxide layer 126 or other suitable solvent.Or fixing layer 124 can be formed as bcb layer, it is bonded to silicon wafer 84 by the thick AP3000 layer of 1nm.Again, simplify in structure in one, consider the expection thickness of diaphragm 44, by grinding or laser ablation by top silicon layer 84 from wafer process to the thickness expected.

Select to provide diaphragm 44 (Figure 17) to the final thickness of wafer 84, it has the final thickness of expectation and it is most preferably chosen as about 0.1 to 50 nanometer.The frequency range (thinner=lower frequency) of the beamformer output signal provided by microarray module 16 is provided, the final thickness of silicon wafer lamella 84 is selected further.

Simplifying in structure in one, providing wafer layer 84 for being directly mounted to partially cured bcb layer 54.But top silicon layer 84 is optionally coated with adhesion promoter layer (not shown) to promote the bonding with partially cured bcb layer 54.

As shown in Figure 17, preform 98,100 is alignd and layer 84 is contacted with BCB structural sheet 54.Align with when contacting at mobile top silicon layer 84 and bcb layer 54, then heat preform 98,100 to solidify bcb layer 54 completely and to realize final bonding and the fusion of silicon layer 84/BCB layer 54, thus closed transducer air gap 42.

Most preferably after silicon wafer 84 is located on Lower Half preform 98, half portion preform 98,100 structure is heated to the initial adhesion temperature of about 150 DEG C, to drive away residual solvent and to realize maximum bonded intensity.Then solidify final at 250 DEG C in nitrogen atmosphere for the half portion 98,100 of bonding about one hour.

After first half preform 100 is arranged on Lower Half preform 98, silicabound layer 126 is dissolved and removes fixing layer 124.Thereafter, final thickness top silicon layer 84 laser ablation extremely can expected to obtain diaphragm barrier film 44 (Figure 17), and preferably reaches the thickness of 0.1 to 5nm, and it has smooth upper space.After laser ablation, chromium contact bed and conductive gold layer 48 are optionally electroplated onto on the top surface of silicon layer 84.After plating, then dissolve bonding coat 122 and remove retaining sheet 120.By using CF ⁴/ H ²optionally dissolve bonding coat 122,126 and remove fixing layer 120,124, thus leave top silicon wafer 84 on the spot as replaceable diaphragm 44.

In one approach, conductive layer 48 is provided as the thick layer gold of 100nm, and it is deposited on the top of film wafer 84.In a kind of alternative structure, rotating and depositing layer gold is to realize the top layers thickness expected on the spot.

Optionally, thereafter fusion wafer assemblies is cut into module 16 size (i.e. 40 × 40 arrays) of the expectation of the independent transducer 20 of the number with expectation.Conductive gold layer 48 provides the electric conductivity from frequency generator 70 to the metal deposition layer 50 formed at sensor backing platform 18.

The row S of the transducer 20 that can drive separately is equipped with at sensor module 14 ₁, S ₂... S ₄₀time (as such as in the figure 7 shown in), layer gold 48 light printing after, thereafter optionally etch layer 48 with by the part of layer remove and electric isolution, thus stay conduction gold thread bonding W ₁, W ₂... W ₄₀, it provides the row S with corresponding transducer ₁, S ₂... S ₄₀electric conductivity.In one embodiment, thereafter by using electroconductive binder, complete CMUT microarray 16 is prepared to be used for the coating metal surfaces 50 being mechanically directly arranged on backing platform 18.

Describe another kind of transducer manufacturing mode referring to figs. 18 to Figure 28, wherein same Reference numeral is for identifying same parts.Implement described method with progressively manufacturing process, it is for engaging silicon backing wafer 80 as back sheet 46 and the BCB top wafer 44 (Figure 26) replacing silicon wafer 84 as top device layer or transducer diaphragm 44.

Figure 18 to Figure 23 illustrates the formation (Figure 23) of the Lower Half preform 98 of each transducer 20.The silicon back sheet 80 formed in the mode of the embodiment substantially according to reference Figure 11 is used to manufacture half portion preform 98.When forming Lower Half preform 98, use the N-type silicon wafer 80 of standard, and it mixes antimony in a large number to realize the resistance of about 0.008 to 0.02 ohm-sq centimetre.Optionally, be easy process, in the mode shown in Figure 11, wafer 80 be fixed to silicon holder 120 by soluble silicon oxide layer 122.Or holder layer can be formed as bcb layer, it is bonded to silicon wafer 80 by the thick AP3000 layer of 1nm.The preferred PCB used in layer 118 will comprise Cyclotene ^tM3022-35, and it dilutes optionally by sym-trimethyl benzene.

The upper surface 108 of silicon wafer 80 is coated with the adhesion promoter layer 106 of an about nanometer thickness, and is preferably AP3000 ^tM, as shown in Figure 18.

After being coated with by adhesion promoter layer 106, ensuing BCB54 structural sheet (Figure 19) is applied in adhesion promoter layer 106.Bcb layer 54 can with suitable thinning agent part of dilution, and rotating and depositing in adhesion promoter layer 106 to provide substantially smooth parallel surfaces and each transducer 20 air gap 42 to be realized to the Z height expected.Most preferably, rotating and depositing is carried out to provide about 500 to 1500 nanometers and the predetermined thickness of most preferably from about 900 nanometers to BCB structural sheet 54.After rotating and depositing, the wafer back lining 80 of coating is placed in an oven and at about 300 DEG C, heats the time of solidifying the half of desired time rating completely about realizing bcb layer 54.Therefore heat to realize that it is partially cured and preferably completely crued about 40% to 60% to bcb layer 54, thus realize turning to partial gel layer (Figure 19) by stable for bcb layer 54.

After partially cured, ensuing photoresist oxidant layer 110 is deposited on the upper surface of gel BCB structural sheet 54.Most preferably, select photic resist layer 110 as the 1805 photoresist oxidant layer of carrying out applying with the thickness of about 0.5 micron.By photoresist oxidant layer 110 (Figure 20) uniform deposition on layer 54, be then exposed to ultraviolet light by printing the light negative mask (photonegativemask) of transducer depression on the photoresist.The photoresist generation chemical change exposed also opposing is washed off, and wherein as shown in Figure 21, unexposed material is easily washed off from exposure layer 54.

Then wafer is placed in the etch bath that the exposure BCB in layer 54 is etched.The exposure area keeping not protected gel BCB structural sheet 54 is removed in etching, and forms independent depression 82 (Figure 22).Preferably carry out the etching long enough period, make depression 82 remove the part of two exposure areas of gel bcb layer 54, and adhesion promoter layer 106 (Figure 22) below.Depression 82 formation has the space of certain size and expectation to serve as the air gap 42 of each transducer 20.Method as discussed previously, is preferably formed in each width in a lateral direction with about 0.03mm, and reaches the depression 82 of the degree of depth of about 2.5 to 4 μm.Although square depression 82 is preferred for maximizing its arrangement space number on backing wafer 80, other shape and orientation can be used.

Preferably not carrying out being etched with makes on the bottom of each depression 82, and silicon back sheet 80 exposes for substantially smooth surface, and preferably has the thickness being chosen as and being less than about 0.5mm.

After the etching, in suitable solvent, wash half portion preform 98, remove the residue of photoresist oxidant layer 110 thus, thus the gel bcb layer 54 (Figure 23) of exposed portion solidification.Then, before finally assembling with selected first half preform 100, half portion preform 98 is washed and cleaned.

In a kind of alternative method forming top half preform 100 and transducer diaphragm 44, provide silica supported wafer (handlingwafer) 124 as shown in Figure 24.Then monox release layer 126 is sputtered to form top-gold layer 48 as shown in Figure 24 with gold.Realized the deposition of layer gold 48 alternatively by conventional electro-plating method, to realize substantially smooth layer gold 48, and deposit with the thickness finally expected.

As shown in Figure 25, after gold plating, by adhesion promoter layer 128 as AP3000 ^tMbe applied in layer gold 48.Most preferably, adhesion promoter layer 128 has and is chosen as about 0.2 to 5nm and the uniform thickness substantially of preferred about 0.5nm.

After adhesion promoter layer 128 deposits, then bcb layer 144 is spin-coated on the top of adhesion promoter layer 128.Bcb layer 144 is applied to form barrier film 44 with selected thickness.Should be appreciated that, the spin coating of bcb layer 144 applies to allow bcb layer 144 to be evenly formed to predetermined thickness.Bcb layer can such as be formed by Cyclotene, and it or may may not dilute the viscosity of the expectation realized for spin coating.Most preferably, bcb layer 144 has wet thickness, and it is through selecting to compensate the expected shrinkage of expecting at final setting up period, and according to sensor application, it is less than about 50nm and the barrier film 44 being preferably the final thickness of about 0.2 to 0.8nm by providing to have.But, thicker or thinner barrier film 44 can be formed.

Figure 27 and Figure 28 illustrates the assembling based on the top preform 100 of BCB and the bcb layer 54 of bottom preform 98 best.Utilize and remain on bcb layer 144 that is wet, its uncured state substantially, and bcb layer 54 remains only about 50% solidification, and the two half-unit preform 98,100 of transducer 20 is moved into alignment (Figure 27) and is placed in vacuum drying oven (not shown).

Before realizing the contact between half portion preform 98,100, baking oven is made to reach perfect vacuum before contact.Under vacuum, wet bcb layer 144 and partially cured bcb layer 54 are overlapped, half portion 98,100 is combined under the moderate pressure being maintained at about 3 Foot-Pounds, and at 300 DEG C heat curing enough time to realize the solidification completely of two bcb layers 144,54.Should be appreciated that at complete setting up period, wet bcb layer 144 is by atrophy and shrink.Shrinkage factor is the given value that provided by manufacturer and depends on grade selected by BCB used, and may up to 10 volume %.

After final solidification, the bonding preform 98,100 of assembled wafers is removed and cools from vacuum drying oven.Then assembly is placed in buffer oxide etch (BOE) bath with selective removal Silica-bound layer 126 and bearing wafer 124 (and if being suitable for, bonding coat 122 and backing wafer holder 120 for silicon wafer 80).The top-gold layer 48 bondd with barrier film 44 is exposed in the removal of silicon oxide layer 126 and the release of processing layer 124, and provides the conductive front side 38 of the transducer 20 of formation.

Although the rear surface 22 being preferred embodiment described in each transducer 20 forms conductive ground layer 50 (Figure 10), the present invention is not limited thereto.In a kind of alternative structure, top conductive layer 48 can be provided to be electrically connected with sensor module 14 ground wire by microarray 16.

Can with reference to Figure 29, it illustrates transducer 20 according to another implementation of the invention, and wherein same Reference numeral is for identifying same parts.In the transducer 20 of Figure 29, in the transducer air gap 42 on the upper surface of silicon bottom layer 46, be provided with conductive gold pad 130.Conductive pad 130 is preferably formed by gold, copper, silver or other conducting metal, and the hole passed through through silicon backing 46 formation or through hole 134, the conductive wire 132 extended by means of the rear surface from conductive pad 130 is electrically coupled to frequency generator 70 (Fig. 9).

As shown in Figure 30 to Figure 33, in the preferred manufacture method of one, substantially select silicon back sheet 80 according to embodiment described in reference diagram 11 at first.After it is formed, back sheet 80 is passed at the central area processing through hole 134 of each expection transducer air gap 42 position, as shown in Figure 30.

After through hole 134 is formed, by filling through hole gold (g) or other selected conducting metal.Then the front surface of back sheet 80 and rear surface are coated with suitable light mask layer 144,146, its through patterning to form conductive pad 130 and the conductive wire 132 (Figure 28) of expectation respectively.Then make to shelter back sheet 80 expose to activate masking layer and carry out washing to remove in masking layer the part that will form pad and conductive wire plating.

Then electroless deposition or sputtering technology is used, by the gold (or other conducting metal) of the thickness that the front surface of layer 80 and rear surface plating are expected, then wash to remove excessive golden sediment, thus leave conductive pad 130 and conductive wire 132 structure of plating.

After washing and final clean and drying, then on metal plating wafer 80, adhesion promoter layer 106 and BCB structural sheet 54 is formed, thus to form half portion preform 98 with reference to the mode described in Figure 19 to Figure 23, and carry out depression etching 82 thus to expose each golden conductive pad 130.Then according to previously described embodiment, preferably half portion preform 98 is engaged with first half preform 100.

Figure 33 illustrates the half portion preform 102 of the transducer 20 formed according to other embodiment, and wherein Reference numeral is for identifying same parts.After bcb layer 54 etches, and the photoresist oxidant layer 110 removed such as shown in Figure 21 is to expose bottom wafer 80 and conductive pad 130.

Preferably, conductive pad 130 is formed as current-carrying plate, and described current-carrying plate has the thickness of about 1 to 2nm in the Z-axis direction, and has the trans D d of the about each cavity 42 of extension (extend) _{on average}50% lateral dimension.At conductive pad 130 throughout at least 50% of the base plate of cavity 82, when activating transducer 20, conductive pad 82 can provide best magnetic flux.

After conductive pad 130 and wire 132 deposit, then such as according to one of previously described mode, selected first half preform 100 is alignd with Lower Half 102 and fixed thereon and with its fusion.

In a kind of preferred structure, independent plate wire 132 is extensible as the single trace of marginal portion to each CMUT microarray module 16, thus according to expection sensor application by transducer 20 individually, selectivity activates group by group or side by side.

Optionally, before gluing one or more other adhesion promotors and/or coating can be applied to substrate and/or top wafer 80,84.Suitable coating can comprise gold or other conductiving metal coating.

As a result, be characterized as following one or more according to the embodiment of the sensor module 14 of aforementioned embodiments:

1. use or simulate the configuration of 3D transducer be shaped (shape) and form acoustic beam;

2. use the ultrasonic system of CMUT technology, it uses or the 3D of simulation CMUT transducer on hyperbolic paraboloid surface arranges shape beam;

3. carry out control wave harness shape by the design of the hyperbolic paraboloid shape of chip and shape, and it controls again the overall width of wave beam, surface is more smooth, then wave beam is wider;

4. limit the size of secondary lobe and the hyperbolic paraboloid shape of effect, produce less interference thus;

5. utilize CMUT transducer, larger signal pressure can be realized in transmission and receiving function;

6. each CMUT transducer can individually, with selected grouping and/or all work simultaneously, provide the extensive ability of beam steering and the target location in wave beam thus; With

7.CMUT transducer designs is little, allows thus to settle more multi-transducer in each level (level), realizes more large-signal intensity and resolution thus.

8. the manufacture simplified and/or the reliability of enhancing.

Although describe the transducer 20 described in each microarray module 16 in detail can vertical bar configuration be electrically connected, the present invention is not limited thereto.The alternate manner of coupled transducers 20 is also possible.Although unrestricted, it is contemplated that, can next generation's grouping of the directed vertical coupled transducer of vertical bar and horizontal bar to allow frequency adjustment in the two directions.

Although the preferable use of monitoring system 12 is provided in vehicle blind spot monitoring, should be appreciated that, its application is not limited thereto.Similarly, be used in automobile sensor 14 although describe the microarray module 16 described based on capacitance type micromachined ultrasonic wave transducer in detail, other application multiple will be apparent now.These application are including but not limited to be applied in the industries such as railway, boats and ships and aircraft, and the purposes relevant with various domestic. applications, medical imaging, industry and business environment and the consumer goods.

Although present specification describes various preferred implementation of the present invention, the invention is not restricted to disclosed ad hoc structure and method.Those of ordinary skill in the art will expect many modifications and changes now.For restriction of the present invention, can with reference to appended claims.

Claims

1. form the method for having the capacitance type micromachined ultrasonic wave transducer (CMUT) in the microarray of multiple transducer, described method comprises:

First silicon-based wafer usually with smooth upper surface and lower surface is provided,

Be provided as the second wafer of device layer, described device layer has usually smooth parallel top surface and basal surface, and described device layer has and is chosen as about 0.05 to 5 micron and the thickness being preferably about 0.2 to 1 micron,

Benzocyclobutene (BCB) layer is formed on one in the described top surface or basal surface of described device layer,

Etch the surface of described bcb layer to form the etched surfaces wherein with multiple depression, each in described depression has preselected geometry, the feature of described depression is that respective sidewall extends to about 0.1 to 15 micron, preferably about 0.2 to 8 micron and the most preferably from about degree of depth of 3 to 4 microns, and

A part for the etched surfaces of bcb layer is alignd with another in the top surface of device layer or basal surface,

Utilize the described bcb layer inserted therebetween by described first wafer bonding extremely described device layer, thus described depression form respective transducer air gap,

Conducting metal is applied at least one in described first wafer and described second wafer.

2. method according to claim 1, wherein said bcb layer comprises the BCB structural sheet with the thickness being greater than about 0.2 micron and described device layer comprises silicon-based devices layer.

3. method according to claim 1, wherein said bcb layer comprises BCB device layer, and described BCB device layer comprises BCB base device layer.

4. the method according to any one in claims 1 to 3, the described upper surface that wherein said forming step is included in described first wafer forms described BCB structural sheet; With

Described device layer was maintained as substantially uncured BCB base device layer before described adhesion step.

5. to described BCB structural sheet, the method according to any one in Claims 1-4, wherein before described etching step, heats that described BCB is partly cured to about 30% to 70% of complete solid state.

6. the method according to any one in claim 1 to 5, wherein said adhesion step comprises described BCB structural sheet is heated to complete solid state, and the BCB in wherein said BCB structural sheet by described first wafer bonding to described device layer.

7. the method according to any one in claim 1 to 6, wherein said etching step comprises light plasma etch.

8. the method according to any one in claim 1 to 7, in addition wherein after bonding, becomes independent microarray with device wafer physical segmentation, that described microarray comprises 9 × 9 transducers or larger square matrices by the first wafer of bonding.

9. the method according to any one in claim 1 to 8, it comprises the lower surface of described top surface or described first wafer conductive metal layer being applied to described device layer at least partially further, described metal is selected from the group be made up of gold, silver and copper, and wherein said conductive metal layer has and is chosen as about 1 to 500 nanometer and is preferably the thickness of about 5 to 50 nanometers.

10. the method according to any one in claim 1 to 9, wherein said geometric configuration comprise have be chosen as about 5 to 100 microns and be preferably the width of about 10 to 40 microns and the usual square shape of length lateral dimension.

11. methods according to any one in claim 1 to 10, the described step wherein forming described depression is included in usual square matrices and forms described depression, and the grouping of wherein said depression is with multiple parallel row and/or column alignment.

12. methods according to any one in claim 1 to 11, the described step wherein applying described conductive metal layer comprises and being coated with the whole top surface of device wafer substantially, and wherein after coating, optionally remove a part for described conductive metal layer to divide into groups described at least some of described depression and adjacent packets electric isolution.

13. methods according to any one in claim 1 to 12, the described step wherein applying described conductive metal layer comprises: before bonding,

The through hole through described first wafer is formed in the respective respective bottom areas of described depression, and

In corresponding bottom section, form conducting metal pad, wherein said conductive pad provides the electric connection with the described lower surface of described first wafer by described through hole.

14. methods according to any one in claim 1 to 13, it comprises further and the grouping of described depression being electrically connected with the changeover module optionally divided into groups described in electric coupling with can operate, and exports to realize stronger signal.

15. methods according to any one in claim 1 to 14, the described step wherein forming described BCB structural sheet comprises with about 1 to 50 micron substantially, and be preferably about 2 to 5 microns, and BCB is applied to the upper surface of the first wafer by the thickness most preferably being 3 to 4 microns.

16. methods according to any one in claim 1 to 15, the described step wherein forming described depression comprises formation at least one hundred depressions and the quadrate array of preferred at least five hundred depressions, and each described depression has usually smooth bottom section.

17. methods according to any one in claim 1 to 16, in addition wherein before described etching, described second wafer is mounted to bearing wafer, and described second wafer is ground and/or laser ablation has the described device layer of the thickness of expectation to be formed.

18. methods according to any one in claim 1 to 17, wherein before the described BCB structural sheet of formation, are applied at least one in described upper surface and lower surface by adhesion promotor coating,

Described adhesion promotor coating has the thickness being chosen as and being less than about 50nm.

19. 1 kinds of methods formed for comprising the condenser type micro Process transducer in the microarray of multiple transducer, described method comprises:

There is provided the silicon backing wafer usually with smooth parallel front surface and rear surface, described backing wafer has the thickness being chosen as about 10 to 500 microns,

Described front surface is formed benzocyclobutene (BCB) structural sheet, and described structural sheet has and is chosen as about 0.5 to 15 micron, preferably about 1 to 10 micron and the most preferably thickness of 3 to 4 microns,

Light plasma etch is carried out to form multiple depression wherein to the surface of described BCB structural sheet, described depression has usually common geometric configuration and is characterised in that respective sidewall usually extends perpendicular to described front surface and extends to the degree of depth of about 0.1 to 10 micron

There is provided and have usually smooth parallel relative front surface and the device layer of rear surface, described device layer has and is chosen as about 0.05 to 10 micron, preferably about 0.2 to 2 micron and be most preferably less than the thickness of 1 micron,

Be arranged as and substantially continuously the rear surface of device wafer bondd on the front surface substantially to seal each depression as respective transducer air gap, and wherein utilize the BCB structural sheet as structure bond composition to be bondd relative to described first wafer by described device wafer

Conductive metal layer is applied in the first wafer and device wafer at least one at least partially.

20. methods according to claim 19, wherein said device wafer comprises silicon-based devices layer.

21. according to claim 19 or method according to claim 20, and wherein said device wafer comprises BCB base device layer.

22. methods according to claim 21, the described front surface that wherein said forming step is included in described first wafer forms described BCB structural sheet; With

Described device layer was maintained as usually uncured BCB base device layer before described adhesion step.

23. according to claim 19 to the method described in any one in 22, wherein before described etching step, to heat with described BCB is partly cured to complete solid state about 30% to 70% and preferably about 50% to described BCB structural sheet.

24. according to claim 19 to the method described in any one in 23, and wherein said adhesion step comprises described BCB structural sheet is heated to complete solid state, and the BCB in wherein said BCB structural sheet by described first wafer bonding to described device wafer.

25. according to claim 19 to the method described in any one in 24, and wherein said etching step comprises and carries out light plasma etch to described BCB structural sheet.

26. according to claim 19 to the method described in any one in 25, wherein after bonding, the first wafer of bonding is become independent microarray with device wafer physical segmentation, that described microarray comprises at least 9 × 9 transducers or larger matrix.

27. according to claim 19 to the method described in any one in 26, it comprises the rear front surface of described front surface or described first wafer conductiving metal coating being applied to described device wafer at least partially further, described metallic coating is selected from the group be made up of gold, silver, copper and its alloy, and wherein said conductive metal layer has and is chosen as about 1 to 500 nanometer and the thickness of preferred about 5 to 20 nanometers.

28. according to claim 19 to the method described in any one in 27, and wherein said geometric configuration comprises having and is chosen as about 5 to 200 microns and the preferred usual square shape of lateral dimension of 10 to 40 microns.

29. according to claim 19 to the method described in any one in 28, and the described step wherein forming described depression comprises and forms described depression with usual square matrices, and the grouping of wherein said depression is with multiple parallel row and/or column alignment.

30. according to claim 19 to the method described in any one in 29, the described step wherein applying described conducting metal comprises and being coated with the whole front surface of device wafer substantially, and wherein after coating, optionally remove a part for described conductiving metal coating to divide into groups described at least some of described depression and adjacent packets electric isolution.

31. according to claim 19 to the method described in any one in 29, and the described step wherein applying described conductiving metal coating comprises: before bonding,

In corresponding bottom section, form conductive pad, wherein said conductive pad provides the electric connection with the described lower surface of described first wafer by described through hole.

32. according to claim 19 to the method described in any one in 31, and it comprises further and the grouping of described depression being electrically connected with the changeover module optionally described grouping being electrically coupled to frequency generator with can operate.

33. according to claim 19 to the method described in any one in 32, the described step wherein forming described BCB structural sheet comprise BCB is applied to the first wafer front surface as substantially parallel layer, this layer has and is chosen as about 1 to 100 micron, preferably about 2 to 25 microns and the most preferably thickness of 3 to 4 microns.

34. according to claim 19 to the method described in any one in 33, and the described step wherein forming described depression comprises and forms at least one hundred depressions and the quadrate array of preferred at least five hundred depressions, and each described depression has usually smooth bottom.

Described device wafer, according to claim 19 to the method described in any one in 34, in addition wherein before described etching, is mounted to bearing wafer by 35., and by described device wafer device layer grinding and/or laser ablation to the thickness expected.

36. according to claim 19 to the method described in any one in 35, wherein before the described BCB structural sheet of formation, adhesion promotor coating is applied at least one in the described front surface of described first wafer and the rear surface of described device wafer, described adhesion promotor coating has the thickness being chosen as and being less than about 50nm, and

Wherein select described adhesion promotor coating with the described BCB structural sheet that bonds.

37. methods according to any one in claims 1 to 36, it comprises further:

There is provided sensor backing platform, described backing platform comprises the usual square mounting surface with the width being chosen as about 0.5 to 10mm,

After bonding, the first wafer of described bonding and device layer are divided into multiple CMUT transducer microarray module comprising multiple transducer, each microarray module has common geometric configuration and has the mean breadth of about 1mm to 2mm,

Selected transducer microarray module is arranged in described mounting surface.

38. according to method according to claim 37, and wherein said installation steps comprise, with usual quadrate array, described CMUT transducer microarray module are mounted to described backing platform.

39. according to claim 37 or method according to claim 38, and it comprises further and forms described backing platform by the ABS usually with smooth module mount surface.

40. methods according to any one in claim 37 or 39, it comprises the described backing platform being formed and have discretize hyperbolic paraboloid mounting surface further, described hyperbolic paraboloid mounting surface comprises multiple discrete flat surfaces of corresponding for receiving in described microarray module thereon, and

And further one selected in described CMUT transducer microarray module to be arranged in described discrete flat surfaces on corresponding one.

41. methods according to any one in claims 1 to 36, the step wherein applying described conductive metal layer comprises the metal level that sputtering is selected from group be made up of gold, silver and copper, and wherein said first conductive metal layer has and is chosen as about 100 to 500 nanometers and the thickness of preferred about 100 nanometers.

42. methods according to any one in Claims 1-4 1, the described step wherein etching described depression comprises carries out plasma etching with the array of usual square or rectangular matrix to described depression, and the described transducer wherein in each microarray module is to align in multiple parallel row and column.

43. 1 kinds for sending and/or the ultrasonic transducer system of receiving sensor wave beam, described system comprises frequency generator and sensor module, and described sensor module comprises:

Backing,

Multiple capacitance type micromachined ultrasonic wave transducer (CMUT) microarray module, described microarray module on described backing with grid matrix orientation arrangement, each described microarray comprises multiple transducers with transducer air gap and diaphragm element, and described microarray module comprises:

There is usually smooth top surface and the bottom silicon layer of basal surface;

There is usually benzocyclobutene (BCB) structural sheet of parallel flat front and rear surface, extend rearward to the multiple depressions in the front surface of BCB structural sheet, described each depression limit the side of corresponding transducer air gap and bottom separately and with array directed and have be chosen as about 0.2 to 5 micron, preferably 3 to 4 microns the degree of depth and be chosen as 5 to 200 microns and the preferred width of 10 to 50 microns, and

Have the device layer of front surface and rear surface, described device layer has and is chosen as about 0.1 to 25 micron and the thickness being preferably less than 1 micron,

BCB structural sheet inserts between the bottom of described device layer and the described top surface of described bottom silicon layer, and described device layer is as each described depression of corresponding transducer diaphragm component sealing simultaneously,

It is one or more that at least one first conductive member is electrically connected in described transducer diaphragm component,

At least one second conductive member inserts between the rear surface of described backing and described bottom silicon layer, and at least one first conductive member described can be electrically connected to ground wire or described frequency generator.

44. sensing systems according to claim 43, wherein said device layer comprises thickness and is chosen as about 0.2 to 5 micron and the silicon base layer being preferably less than 1 micron.

45. sensing systems according to claim 43, wherein said device layer comprises thickness and is chosen as about 0.2 to 5 micron and the bcb layer being preferably less than 1 micron.

46. sensing systems according to any one in claim 43 to 45, wherein said BCB structural sheet has and is chosen as about 1 micron of to 40 microns and preferably thickness of about 3 microns to 4 microns, and wherein said BCB structural sheet has the thickness of at least half degree of depth being chosen as described depression between adjacent described air gap.

47. sensing systems according to any one in claim 43 to 46, wherein said depression comprises with the usual square depression of usual square matrices array orientation.

48. sensing systems according to any one in claim 43 to 47, it comprises the adhesion promotor coating between at least one in the part and described bottom silicon layer and described device layer inserting described BCB structural sheet further.

49. sensing systems according to any one in claim 43 to 48, it comprises multiple described first conductive member, described first conductive member, described first conductive member is electrically connected the respective packets of the described transducer diaphragm component in each CMUT microarray separately, and comprises further

Changeover module, described changeover module can activate one or more with what be optionally connected to by described frequency generator in described first conductive member, optionally to activate the respective packets of transducer.

50. sensing system, wherein said first conductive member and each self-contained conductiving metal coatings of described second conductive member according to any one in claim 43 to 49.

51. sensing systems according to any one in claim 43 to 50, wherein each described grouping comprises the column grouping of described transducer.

52. sensing systems according to any one in claim 43 to 51, wherein said array comprises at least 25 depressions, preferably at least 100 depressions and the usual quadrate array of more preferably at least 400 depressions.

53. sensing systems according to any one in claim 43 to 52, wherein said sensor module comprises the auxiliary or blind-spot sensors of programmable vehicle parking.

54. sensing systems according to any one in claim 43 to 53, wherein sent sensor wave beam has and is chosen as 50 to 200kHz and the frequency being preferably about 150 to 163kHz.

55. 1 kinds for sending and/or the ultrasonic transducer system of receiving sensor wave beam, described system comprises frequency generator and sensor module, and described sensor module comprises

Multiple capacitance type micromachined ultrasonic wave transducer (CMUT) microarray module, described microarray module arrangement becomes common matrix directed, each described microarray module comprises multiple condenser type micro Process transducer with transducer air gap and diaphragm element, described condenser type micro Process transducer is formed by the method according to any one in Claims 1-4 2, and wherein said microarray module comprises:

There is the bottom silicon layer of usual planar top surface,

BCB structural sheet, described BCB structural sheet to be arranged on described top surface and to have the multiple square depression formed wherein, described each depression limit the side of corresponding described transducer air gap and bottom separately and with usual quadrate array directed and have be chosen as about 0.2 to 10 micron and preferably 3 to 4 microns the degree of depth and be chosen as 5 to 100 microns and the preferred width of 10 to 40 microns, and

Cover the top device layer of described BCB structural sheet, described device layer seals each described depression as corresponding described transducer diaphragm component and has the thickness being chosen as about 0.1 to 5 micron, and

At least one conductive member, it extends and can be electrically connected to ground wire or described frequency generator in the part of one of described diaphragm element.

56. sensing systems according to claim 55, it comprises multiple described conductive member, and described conductive member is electrically connected the grouping of the multiple described transducer in each CMUT microarray, and its work is to produce the output frequency of relative broad range.

57. sensing systems according to claim 55 or claim 56, wherein each described grouping comprises the column grouping of described transducer.

58. sensing systems according to claim 55, it comprises multiple described conductive member, and described conductive member is electrically connected the corresponding described transducer in each CMUT microarray individually.

59. sensing systems according to any one in claim 55 to 58, wherein said quadrate array comprises at least 25 depressions and the array of preferred at least 400 depressions.

60. sensing systems according to any one in claim 55 to 59, wherein said sensor wave beam has and is chosen as 50 to 200kHz and the frequency of preferred about 150 to 163kHz.

61. sensing systems according to any one in claim 55 to 60, wherein said device layer comprises silicon wafer, and described silicon wafer has and is chosen as about 0.2 to 4 micron and the thickness being preferably less than 1 micron.

62. sensing systems according to any one in claim 55 to 60, wherein said device layer is made up of bcb layer substantially, and described bcb layer has and is chosen as about 0.2 to 4 micron and the thickness being preferably less than 1 micron.