CN106315506A - Micromachining technology for manufacturing composite capacitive micromachined ultrasonic transducer - Google Patents
Micromachining technology for manufacturing composite capacitive micromachined ultrasonic transducer Download PDFInfo
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- CN106315506A CN106315506A CN201610655181.0A CN201610655181A CN106315506A CN 106315506 A CN106315506 A CN 106315506A CN 201610655181 A CN201610655181 A CN 201610655181A CN 106315506 A CN106315506 A CN 106315506A
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- cmut
- low frequency
- soi wafer
- high frequency
- cavity
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B81—MICROSTRUCTURAL TECHNOLOGY
- B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
- B81C3/00—Assembling of devices or systems from individually processed components
- B81C3/001—Bonding of two components
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
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- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Mechanical Engineering (AREA)
- Transducers For Ultrasonic Waves (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
Abstract
The invention relates to a micromachining technology and a related composite capacitive micromachined ultrasonic transducer and provides a processing manufacturing method for the composite capacitive micromachined ultrasonic transducer (composite CMUT). Through utilization of the method, high frequency and low frequency structures in a CMUT unit can be easily realized in the single CMUT unit. The high frequency structure and the low frequency structure of the CMUT unit are realized on different silicon wafers. The high frequency structure and the low frequency structure are combined through silicon wafer bonding, and the composite CMUT unit is realized. According to the technology, double SOI silicon wafer bonding is employed, technological steps are few, mask plates are few (there are only three mask plates), the technology is simple and reliable, mass production can be realized, the processing cost is relatively low, the device sensitivity is high, the performance consistency is good, and a rate of finished products is high.
Description
Technical field
The present invention relates to MEMS (MEMS) and biomedical engineering technology field, particularly relate to manufacture compound microcomputer
The micro fabrication of tool capacitive ultrasound transducer.
Background technology
At present, in ultra sonic imaging is applied, sensor array is to rise in imaging device to determine main critical component, its matter
Amount is the deciding factor of image quality.So, urgent needs have reliable, effective, concordance is good, highly sensitive, low cost also
Can mass-producted manufacture method.
Generally comprise for processing piezoelectric micromotor mechanical ultrasonic for processing the current techniques of sonac and array thereof
The technology of sensor (pMUT) and capacitive micromachined ultrasonic transducer (CMUT) and the technology of array thereof.The process technology of pMUT
Relate generally to micro Process thin-film technique and laminated piezoelectric micro fabrication.Capacitive micromachined ultrasonic transducer (CMUT) and battle array thereof
The current techniques of row, it relates in general to sacrificial layer release process or wafer bonding techniques.Document " Capacitive
Micromachined Ultrasonic Transducers:Fabrication Technology ", A. S. Ergun etc.,
IEEE Transactions on Ultrasonic Ferroelectrics and Frequency Control, 52(12),
2005 pairs relate to currently processing CMUT method and are summarized.
Due to the limitation of traditional diamond-making technique, it is difficult to acquisition less than the micro structure of ultrasonic wavelength or processing cost is the most high
Expensive.The appearance of micromachining technology and development, can be easily carried out less than the micro structure of ultrasonic wavelength.For realizing
Meeting the structure of multifrequency demand, CMUT has the biggest advantage.Because using the sensor of piezoelectric is by changing piezoelectricity
The thickness of material obtains different frequencies, so, it is difficult to go to realize not thickness by micro-processing technology at same microsensor
Piezoelectric layer.And, in medical application, piezo ultrasound transducers must have the matching layer of different-thickness.This makes piezoelectricity surpass
Sonic transducer is more difficult to application.And use capacitive sonac, thus it is possible to vary planar dimension, and keep consistency of thickness just
Different frequencies can be obtained.Therefore, the multi-frequency combination structure of sensor can be easily realized by micro Process.This is also this project
The basis that the structure proposed can easily realize.It addition, for traditional PZT material, when applied environment temperature is higher than curie point,
About during 350 C, its piezoelectric property can fade away, thus sensor performance is deteriorated, until losing efficacy.And CMUT is at applied environment
When temperature reaches 500 C, remain to normally work.
From the point of view of the processing of CMUT, no matter use the technique such as sacrificial layer release process and too much surface deposition
The quality or the mass parameter of vacuum cavity that are thin film are unstable, easily cause properties of product unstable, make the sensitive of sensor
Degree reduces.The patent of invention of China, the patent of Patent No. CN200680006795.0 discloses a kind of manufacture micro Process electric capacity
The surface micromechanical process of formula sonac, the base structure of the disclosed CMUT of this application, need to use six thin-film depositions
With six lithography steps.And too much mask plate and processing step can make to increase positive error, greatly affect the knot of sensor
Structure, ultimately results in sensor performance and is greatly lowered, and makes yield rate reduce.
Summary of the invention
It is an object of the invention to provide the micro fabrication manufacturing composite micromechanical capacitive ultrasound transducer, make processed
In journey, photoetching number of times reduces, and processing step is simple, the transducer sensitivity that produces is high, consistency of performance is good.
The technical solution used in the present invention is:
Manufacture the micro fabrication of composite micromechanical capacitive ultrasound transducer, comprise the following steps:
Step one, obtain the low frequency configuration of CMUT at the first soi wafer: to use substrate be that boron heavily mixes is the first electrode (6)
Soi wafer forms CMUT low frequency cavity and the supporter (4) of vibration film, described support through figure conversion photoengraving device layer
Body (4) is isolated by silicon dioxide insulating layer (5) with the first electrode (6)；
Step 2, obtain the high-frequency structure of CMUT at the second soi wafer: use the soi wafer that do not mixes of substrate to turn through figure
Change photoengraving device layer and form high frequency cavity and high frequency cavity knee wall (3)；
Step 3, two the SOI silicon chips laggard line unit staggered relatively above-mentioned steps one and step 2 made close, and form low frequency
Vacuum cavity；
Silicon chip after step 4, para-linkage carries out reduction processing, and in removal, the substrate layer (8) of silicon chip forms vibration film (1)；
Step 5, by metal sputtering and etching formed the second electrode (7), produce composite micromechanical condenser type ultrasonic transduction
Device.
Reduction processing in described step 4 uses CMP chemical thinning processes.
High frequency cavity knee wall (3) in described step 2 is formed by device layer.
The present invention is by obtaining high-frequency structure and the low frequency configuration of CMUT respectively on different silicon chips so that compound CMUT
Structure is achieved；And using double soi wafer, the flatness of the vibrating elastic film of CMUT reaches nanometer scale, meanwhile, CMUT's
The base plane degree of vacuum cavity equally reaches nanometer scale, increases the frequency range of CMUT, can be effectively improved sensor
Sensitivity；The invention provides a kind of photoetching few, it is only necessary to three mask plates, processing step is few and simple, improves properties of product
Stability and concordance；Owing to this technology is based on the micro-processing technology being characterized with batch production and miniaturization, so, this skill
The realization of art is it would appear that low price is by substrate with ultrasound medicine equipment low frequency part portative, as smart mobile phone
It is that matrix processes for the boron doped SOI of severe.
Accompanying drawing explanation
Fig. 1 is the structural representation of the low frequency configuration obtaining CMUT at the first soi wafer of the present invention；
Fig. 2 is the structural representation of the high-frequency structure obtaining CMUT at the second soi wafer of the present invention；
Fig. 3 is the structural representation producing composite micromechanical capacitive ultrasound transducer of the present invention；
Fig. 4 is the flow chart of the present invention.
Detailed description of the invention
As shown in Fig. 1,2,3 and 4, the present invention includes comprising the following steps:
Step one, obtain the low frequency configuration of CMUT at the first soi wafer: to use substrate be that boron heavily mixes is the first electrode (6)
Soi wafer forms CMUT low frequency cavity parameters and the supporter (4) of vibration film through figure conversion photoengraving device layer, described
Supporter (4) is isolated by silicon dioxide insulating layer (5) with the first electrode (6)；
Step 2, obtain the high-frequency structure of CMUT at the second soi wafer: use the soi wafer that do not mixes of substrate to turn through figure
Change photoengraving device layer and form high frequency cavity parameters and high frequency cavity knee wall (3)；High frequency cavity in described step 2 props up
Buttress (3) is formed by device layer.
Step 3, two the SOI silicon chips laggard line unit staggered relatively above-mentioned steps one and step 2 made close, and are formed
Low frequency vacuum cavity；
Silicon chip after step 4, para-linkage carries out reduction processing, and in removal, the substrate layer (8) of silicon chip forms vibration film (1)；Institute
Reduction processing in the step 4 stated uses CMP chemical thinning processes.
Step 5, by metal sputtering and etching formed the second electrode (7).Produce that composite micromechanical condenser type is ultrasonic to be changed
Can device
First the present invention obtains the high-frequency structure of CMUT on the first soi wafer, obtains the low frequency of CMUT on the second soi wafer
Structure；Then, using double soi wafer, the flatness of the vibrating elastic film of CMUT reaches nanometer scale, meanwhile, and the vacuum of CMUT
The base plane degree of cavity equally reaches nanometer scale.Owing to high-frequency structure and the low frequency configuration of CMUT of the present invention exist respectively
Realize on different silicon chips, and by wafer bonding by high and low frequency structural grouping, it is achieved that compound CMUT unit.
For low frequency part in the present invention, inherent character determines that its physical dimension is relatively big, and HFS is then contrary, its knot
Structure size is less, and its concrete dimensional parameters then can be configured as required.Accordingly, can build in the bottom of elastica
The support structure of structure HFS.In this manner it is possible to HFS and low frequency part are combined in a vacuum cavity, i.e.
HFS and low frequency part are processed in a CMUT unit, and do not increase the physical dimension of CMUT unit.At application low frequency
Part occasion time, HFS does not affect low frequency part and plays a role；In the occasion of application HFS, vibrating diaphragm is at low frequency
Under the collapse voltage of part, high frequency supporting construction territory adopting bottom electrode contact, thus form high-frequency structure, meet frequency applications field
Close.
Claims (3)
1. manufacture the micro fabrication of composite micromechanical capacitive ultrasound transducer, it is characterised in that: comprise the following steps:
Step one, obtain the low frequency configuration of CMUT at the first soi wafer: to use substrate be that boron heavily mixes is the first electrode (6)
Soi wafer forms CMUT low frequency cavity and the supporter (4) of vibration film, described support through figure conversion photoengraving device layer
Body (4) is isolated by silicon dioxide insulating layer (5) with the first electrode (6)；
Step 2, obtain the high-frequency structure of CMUT at the second soi wafer: use the soi wafer that do not mixes of substrate to turn through figure
Change photoengraving device layer and form high frequency cavity and high frequency cavity knee wall (3)；
Step 3, two the SOI silicon chips laggard line unit staggered relatively above-mentioned steps one and step 2 made close, and form low frequency
Vacuum cavity；
Silicon chip after step 4, para-linkage carries out reduction processing, and in removal, the substrate layer (8) of silicon chip forms vibration film (1)；
Step 5, by metal sputtering and etching formed the second electrode (7), produce composite micromechanical condenser type ultrasonic transduction
Device.
The micro fabrication of manufacture composite micromechanical capacitive ultrasound transducer the most according to claim 1, its feature exists
In: the reduction processing in described step 4 uses CMP chemical thinning processes.
The micro fabrication of manufacture composite micromechanical capacitive ultrasound transducer the most according to claim 2, its feature exists
In: high frequency cavity knee wall (3) in described step 2 is formed by device layer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201610655181.0A CN106315506A (en) | 2016-08-11 | 2016-08-11 | Micromachining technology for manufacturing composite capacitive micromachined ultrasonic transducer |
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| CN201610655181.0A CN106315506A (en) | 2016-08-11 | 2016-08-11 | Micromachining technology for manufacturing composite capacitive micromachined ultrasonic transducer |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110217753A (en) * | 2019-05-16 | 2019-09-10 | 西安交通大学 | A kind of through-hole capacitance type micromachined ultrasonic energy converter and preparation method thereof |
| CN110711312A (en) * | 2019-11-07 | 2020-01-21 | 河南大学 | Micro-electromechanical system based strong permeation-promoting transdermal drug release micro-system and manufacturing method thereof |
| CN113560158A (en) * | 2021-08-27 | 2021-10-29 | 南京声息芯影科技有限公司 | Piezoelectric micromechanical ultrasonic transducer, array chip and manufacturing method |
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| US20080048211A1 (en) * | 2006-07-20 | 2008-02-28 | Khuri-Yakub Butrus T | Trench isolated capacitive micromachined ultrasonic transducer arrays with a supporting frame |
| EP1992290A1 (en) * | 2006-03-03 | 2008-11-19 | Olympus Medical Systems Corp. | Ultrasonic vibrator and body cavity ultrasonograph having the ultrasonic vibrator |
| US20100173437A1 (en) * | 2008-10-21 | 2010-07-08 | Wygant Ira O | Method of fabricating CMUTs that generate low-frequency and high-intensity ultrasound |
| EP2728904A1 (en) * | 2011-06-27 | 2014-05-07 | Ingen MSL Inc. | Vibrating element and method for producing vibrating element |
| CN104907241A (en) * | 2015-06-17 | 2015-09-16 | 河南大学 | Broadband ultrasonic transducer composite mechanism satisfying multifrequency requirement |
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2016
- 2016-08-11 CN CN201610655181.0A patent/CN106315506A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1992290A1 (en) * | 2006-03-03 | 2008-11-19 | Olympus Medical Systems Corp. | Ultrasonic vibrator and body cavity ultrasonograph having the ultrasonic vibrator |
| US20080048211A1 (en) * | 2006-07-20 | 2008-02-28 | Khuri-Yakub Butrus T | Trench isolated capacitive micromachined ultrasonic transducer arrays with a supporting frame |
| US20100173437A1 (en) * | 2008-10-21 | 2010-07-08 | Wygant Ira O | Method of fabricating CMUTs that generate low-frequency and high-intensity ultrasound |
| EP2728904A1 (en) * | 2011-06-27 | 2014-05-07 | Ingen MSL Inc. | Vibrating element and method for producing vibrating element |
| CN104907241A (en) * | 2015-06-17 | 2015-09-16 | 河南大学 | Broadband ultrasonic transducer composite mechanism satisfying multifrequency requirement |
Non-Patent Citations (2)
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| 冯丽萍，刘正常: "《薄膜技术与应用》", 29 February 2016 * |
| 魏希文，陈国栋: "《多晶硅薄膜及其应用》", 31 August 1988 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110217753A (en) * | 2019-05-16 | 2019-09-10 | 西安交通大学 | A kind of through-hole capacitance type micromachined ultrasonic energy converter and preparation method thereof |
| CN110217753B (en) * | 2019-05-16 | 2022-02-01 | 西安交通大学 | Through-hole capacitive micro-machined ultrasonic transducer and preparation method thereof |
| CN110711312A (en) * | 2019-11-07 | 2020-01-21 | 河南大学 | Micro-electromechanical system based strong permeation-promoting transdermal drug release micro-system and manufacturing method thereof |
| CN113560158A (en) * | 2021-08-27 | 2021-10-29 | 南京声息芯影科技有限公司 | Piezoelectric micromechanical ultrasonic transducer, array chip and manufacturing method |
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