CN111669143A - Piezoelectric resonance micro-channel for liquid detection and preparation method thereof - Google Patents
Piezoelectric resonance micro-channel for liquid detection and preparation method thereof Download PDFInfo
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- H—ELECTRICITY
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- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
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- B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
- B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
- B01L3/5027—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip
- B01L3/502707—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip characterised by the manufacture of the container or its components
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- H—ELECTRICITY
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- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
Abstract
The invention provides a piezoelectric resonance micro-channel for liquid detection and a preparation method thereof, which are characterized by comprising an active piezoelectric layer for fixing electrodes, wherein the active piezoelectric layer is fixed on a silicon substrate, and the electrodes are used for driving resonance. The structure piezoelectric layer is arranged above the active piezoelectric layer, a cavity is formed between the two piezoelectric layers by utilizing a sacrificial layer process, and the active piezoelectric layer, the cavity and the structure piezoelectric layer are combined to form a resonance micro-channel structure. The resonant micro-channel structure can be released to form a suspension structure, or not released. When the micro-channel structure works, liquid is injected into the micro-channel structure, the resonant frequency of the resonant micro-channel structure changes due to the fact that the resonant frequency is full of the liquid, the viscous damping of different liquids is different, the influence degree on the resonant frequency is also different, and the detection process is completed by comparing the viscous damping with the intrinsic resonant frequency in the air environment.
Description
Technical Field
The invention relates to a micro-electro-mechanical system (MEMS) resonance micro-channel based on piezoelectric materials and a manufacturing process thereof, in particular to a piezoelectric resonance nano-channel capable of working in a high-damping liquid environment and a manufacturing process thereof, which can be applied to biological and chemical detection and other directions and belong to the technical field of piezoelectric sensors.
Background
In analytical tests in the fields of chemistry, biology and the like, the reduction of the amount of the minimum detection reagent required and the detection of very low concentrations of the target analyte are the direction of efforts for all detection means. Over the past few decades, significant advances have been made in microelectromechanical systems (MEMS) based piezoelectric resonators, so that miniaturized devices based on this technology can be adapted to an increasing number of fields requiring integratable sensors. In recent decades, due to the improvement of the quality factor and the reduction of the quality of the resonator, the sensor based on the resonator structure can directly measure the mass of the nanometer particles and the single molecules, and high-resolution detection is realized. With the design optimization of nanomechanical structures, it is believed that such miniaturized devices ultimately achieve resolution at the single proton level (see document [1 ]: Lee J, Shen W, Payer K, et al. aware approach mass measurements with suspended nanochannel detectors [ J ]. Nano letters,2010,10(7): 2537:. 2542.) for detection of very low concentrations of target analytes in the fields of chemistry, biology, and the like. However, when the resonator is directly operated in a liquid environment, due to the existence of viscous resistance, the effective mass is increased and the energy dissipation of the resonant cavity is remarkably increased, the performance of the device is seriously affected, the frequency resolution of the device is reduced, and therefore, the realization of effective conduction and the enhancement of the interaction between the fluid and the device in the liquid environment becomes more challenging. The use of micromechanical cantilever resonators (see document [2] Yue M, Stachowiak J C, Lin H, et al. Label-free proteinaceous recording and two-dimensional array using nanomechanical sensors [ J ]. Nanoleters, 2008,8(2):520 and 524.) has been shown to partially overcome these problems, cantilever resonators can achieve greater displacement to resist the effects of viscous damping on device performance. However, this method of integrating the microfluidic channel inside the cantilever sensor requires a large bias voltage (see document [2]), limiting the resolution of some applications.
At present, the development of the nano resonant channel based on the piezoelectric material is not mature enough, and the quality factor of the resonator is greatly reduced due to the existence of viscous resistance and the energy dissipation of the resonant cavity. The lower operating frequency (100kHz) of the currently designed suspended resonant nanochannels limits the dynamic range of the device when the operating frequency is lowered.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: how to reduce the demand of the tested agent and how to solve the influence of viscous damping on the device performance through structural design, and improve the detection resolution of the sensor.
In order to solve the technical problems, the technical idea of the invention is as follows: the micro-channel and the resonator are combined to form the resonant cavity, the micro-channel can be used for reducing the demand of the detected reagent, the detection can be completed only by a small amount of reagent, the influence of viscous damping on the performance of the device is reduced by designing and optimizing the parameters of the resonant cavity, and the higher frequency resolution, namely the detection resolution is realized.
Based on the technical concept, a specific technical solution of the present invention is to provide a piezoelectric resonance micro flow channel for liquid detection, which is characterized by comprising:
the active piezoelectric layer is fixed on the silicon substrate and used for fixing electrodes which are used for exciting a resonance mode, and the roots of the electrodes with the same polarity are communicated with each other; (ii) a
The structure piezoelectric layer is positioned above the active piezoelectric layer, the active piezoelectric layer and the structure piezoelectric layer are connected by a cavity formed by a sacrificial layer process or directly according to different driving modes, and the active piezoelectric layer, the cavity and the structure piezoelectric layer are combined to form a resonance micro-channel structure;
the through hole I and the through hole II are respectively used for leading out the upper electrode and the lower electrode;
the first etching hole and the second etching hole are positioned on the piezoelectric layer of the structure, and the first etching hole and the second etching hole are used for defining the boundary of the device region and providing an etching groove for forming a cavity;
the first filling layer and the second filling layer are used for filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer;
and the tested agent is injected into the resonant micro-channel structure through the through hole.
Preferably, the structural piezoelectric layer is fixed on the silicon substrate as a resonance body, the structural piezoelectric layer has a plurality of resonance periods in a transverse cross section, and the electrodes are used for resonance of the resonator by means of a piezoelectric effect.
Preferably, the electrodes have 4 arrangements according to the driven resonance modes: using a surface wave resonance mode, wherein an electrode above the active piezoelectric layer is an interdigital electrode, and no electrode is arranged below the active piezoelectric layer; using a profile resonance mode or a vertical electric field lamb wave resonance mode, wherein an upper electrode of the active piezoelectric layer is an interdigital electrode, and a lower electrode of the active piezoelectric layer is also an interdigital electrode; using a transverse electric field lamb wave resonance mode, wherein an upper electrode of the active piezoelectric layer is an interdigital electrode, and a lower electrode of the active piezoelectric layer is a flat plate electrode; and using a vertical bulk acoustic wave resonance mode, wherein the upper electrode of the active piezoelectric layer is a flat plate electrode, and the lower electrode of the active piezoelectric layer is also a flat plate electrode.
Preferably, when the surface wave resonance mode is used, the active piezoelectric layer is connected with the silicon substrate through the cavity or directly; when the contour resonance mode, the vertical electric field lamb wave resonance mode, the transverse electric field lamb wave resonance mode or the vertical bulk acoustic wave resonance mode is used, the active piezoelectric layer is connected with the silicon substrate through the cavity, the silicon substrate/sacrificial layer forms a recess below a device area, and the device area is suspended, so that acoustic waves are reflected at the interface of the piezoelectric material and air.
Preferably, the active piezoelectric layer and the structural piezoelectric layer are made of aluminum nitride, lithium niobate, lithium tantalate or lead zirconate titanate; the electrode is made of metal materials.
Preferably, the material of the electrode is aluminum, gold, platinum, molybdenum, copper or tungsten.
Another technical solution of the present invention is to provide a method for preparing the resonant micro channel using a profile resonance mode or a vertical electric field lamb wave resonance mode, comprising the steps of:
step 1): depositing a lower electrode of the electrode on the silicon substrate and patterning the lower electrode;
step 2): depositing a first layer of piezoelectric material over the lower electrode as an active piezoelectric layer;
step 3): depositing a metal over the active piezoelectric layer and patterning into an upper electrode;
step 4): depositing and patterning a sacrificial layer over the upper electrode;
step 5): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 6): etching the structural piezoelectric layer to form a through hole connected with the upper electrode;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 8): etching the sacrificial layer by using isotropic etching to form a cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 9): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole connected with the lower electrode;
step 11): and etching the structural piezoelectric layer and the active piezoelectric layer, defining the boundary of the device region, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel, namely obtaining the resonance micro-channel using the contour resonance mode or the vertical electric field lamb wave resonance mode.
Another technical solution of the present invention is to provide a method for preparing the resonant micro channel using a surface wave resonance mode, including the steps of:
step 1): depositing a first layer of piezoelectric material over a substrate as an active piezoelectric layer;
step 2): depositing a metal over the active piezoelectric layer and patterning into an upper electrode;
step 3): depositing and patterning a sacrificial layer over the upper electrode;
step 4): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 5): etching the structural piezoelectric layer to form a through hole connected with the upper electrode;
step 6): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 7): etching the sacrificial layer by using isotropic etching, wherein the cavity is formed between the active piezoelectric layer and the structural piezoelectric layer;
step 8): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer, so as to obtain the resonant micro-channel using the surface wave resonant mode.
Another technical solution of the present invention is to provide a method for preparing the above resonant micro flow channel using a transverse electric field lamb wave resonance mode, comprising the steps of:
step 1): depositing a flat lower electrode of the electrode on the silicon substrate;
step 2): depositing a first layer of piezoelectric material over the lower electrode as an active piezoelectric layer;
step 3): depositing a metal over the active piezoelectric layer and patterning into an upper electrode;
step 4): depositing and patterning a sacrificial layer over the upper electrode;
step 5): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 6): etching the structural piezoelectric layer to form a through hole connected with the upper electrode;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 8): etching the sacrificial layer by using isotropic etching, wherein the cavity is formed between the active piezoelectric layer and the structural piezoelectric layer;
step 9): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole connected with the lower electrode of the flat plate;
step 11): and etching the piezoelectric layer and the active piezoelectric layer of the structure, defining the boundary of the device area, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel, namely obtaining the resonance micro-channel using the transverse electric field lamb wave resonance mode.
The invention also provides a preparation method of the resonant micro-channel using the vertical bulk acoustic wave resonant mode, which is characterized by comprising the following steps
Step 1): depositing a lower electrode of the electrode on the silicon substrate and patterning the flat lower electrode;
step 2): depositing a first layer of piezoelectric material over the lower electrode as an active piezoelectric layer;
step 3): depositing metal above the active piezoelectric layer and patterning the metal into a flat upper electrode;
step 4): depositing and patterning a sacrificial layer over the upper electrode;
step 5): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 6): etching the structural piezoelectric layer to form a through hole connected with the upper electrode of the flat plate;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 8): etching the sacrificial layer by using isotropic etching, wherein the cavity is formed between the active piezoelectric layer and the structural piezoelectric layer;
step 9): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole connected with the lower electrode of the flat plate;
step 11): and etching the piezoelectric layer and the active piezoelectric layer of the structure, defining the boundary of the device area, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel, namely obtaining the resonance micro-channel using the vertical bulk acoustic wave resonance mode.
In order to solve the problems in the prior art, the sensor is composed of a piezoelectric nano micro-channel which vibrates transversely or longitudinally, the size and the process of the micro-channel are designed and optimized, so that the piezoelectric nano-channel can work in a certain damped liquid environment, high precision is realized, high voltage is not required to be used as electrostatic drive and complex optical reading, and the sensor can be applied to biological and chemical detection and other directions.
Drawings
FIG. 1a is a cross-sectional view of a resonant micro flow channel of a profile resonance mode or a vertical electric field lamb wave resonance mode provided in example 1;
FIG. 1b is a top view of the surface wave resonance mode piezoelectric microchannel in the cross section of the upper electrode provided in example 3;
FIG. 1c is a schematic diagram of the resonant frequency of the resonant micro channel of the profile resonance mode or the vertical electric field lamb wave resonance mode provided in example 2, respectively, operating in air and liquid;
FIG. 1d is a top view of a micro flow channel and a piezoelectric micro flow channel of a surface wave resonance mode provided in example 3;
FIGS. 2a to 2k are schematic views showing states at different steps in the method for preparing a resonant micro channel in a profile resonance mode or a vertical electric field lamb wave resonance mode according to example 2;
FIGS. 3a to 3i are schematic views showing states at different steps in the method for preparing a surface wave resonance mode piezoelectric microchannel provided in example 3;
FIGS. 4a to 4k are schematic diagrams illustrating states at different steps in the method for preparing a piezoelectric microchannel having a transverse electric field lamb wave resonance mode according to example 4;
FIG. 5a is a schematic diagram of a piezoelectric microchannel of a vertical bulk acoustic wave resonance mode provided in example 5;
fig. 6a is a schematic diagram of a protective layer deposited in the step of depositing a patterned upper electrode on the resonant micro channel of the profile resonance mode or the vertical electric field lamb wave resonance mode provided in example 6.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Example 1
As shown in fig. 1a, a micro-electromechanical system (MEMS) resonant micro flow channel based on piezoelectric material using a profile resonance mode or a vertical electric field lamb wave resonance mode provided for this embodiment includes an active piezoelectric layer 7 for fixing upper electrodes 1b, 2b, 3b, 4b and lower electrodes 1a, 2a, 3a, 4a, the active piezoelectric layer 7 is fixed on a silicon substrate 12, and the upper electrodes and the lower electrodes are used for exciting the profile resonance mode or the vertical electric field lamb wave resonance mode. The upper electrode and the lower electrode are both patterned into interdigital electrodes, and the roots of the electrodes with the same polarity are mutually communicated. A structural piezoelectric layer 14 is arranged above the active piezoelectric layer 7, a cavity 18 formed by a sacrificial layer process is arranged between the active piezoelectric layer 7 and the structural piezoelectric layer 14, and the active piezoelectric layer 7, the cavity 18 and the structural piezoelectric layer 14 are combined to form a resonant micro-channel structure. The through holes 5 and 9 are used to lead out the upper electrodes 1b, 2b, 3b, 4b and the lower electrodes 1a, 2a, 3a, 4a, respectively. Two etch holes 17a, 17b are located in the piezoelectric layer 14, the etch holes 17a, 17b being used to define the device region boundaries and to provide etch trenches for forming the cavity 13. The filling layers 8a, 8b fill the trenches used for etching the sacrificial layer, closing the cavity 18 between the active piezoelectric layer 7 and the structural piezoelectric layer 14. FIG. 1b is a cross-sectional view at the device electrode, and the through-holes 19a, 19b are the test agent injection holes, as shown in FIG. 1 b. Wherein the active piezoelectric layer 7 and the structural piezoelectric layer 14 are made of aluminum nitride, lithium niobate, lithium tantalate or lead zirconate titanate; the upper electrodes 1b, 2b, 3b, 4b and the lower electrodes 1a, 2a, 3a, 4a are made of metal materials, such as aluminum, gold, platinum, molybdenum, copper or tungsten.
When the micro-channel structure works, liquid is injected into the micro-channel cavity 18 through the injection hole 19a or the injection hole 19b, the resonant frequency of the resonant micro-channel structure changes due to the fact that the resonant micro-channel structure is filled with the liquid, the viscous damping of different liquids is different, the influence degree on the resonant frequency is different, and the liquid is compared with the intrinsic resonant frequency in the air environment to complete the detection process.
As shown in fig. 1c, curve one (air) is the admittance curve of the resonant microchannel at resonance in air, and f2 is the resonance frequency of the resonant microchannel; curve two (liquid) is the admittance curve of the resonant micro-channel when resonating in liquid, and f1 is the true resonant frequency of the resonant micro-channel; Δ f is the difference between the resonant frequencies of the resonant microchannel when operating in air and liquid, respectively, and the detection process is completed by detecting the resonant frequency in the liquid and comparing it with the eigen-resonant frequency in the air environment.
As shown in fig. 1d, fig. 1d is a top view of a micro-channel and a piezoelectric micro-channel in a surface wave resonance mode, wherein liquid is injected into the micro-channel through a liquid inlet, the liquid flows in the micro-channel from the liquid flow direction, the resonant frequency is detected when the liquid passes through the resonant micro-channel, the liquid flows in the micro-channel again from the liquid flow direction until the liquid outlet, and the detection process is completed by comparing the resonant frequency in the liquid with the intrinsic resonant frequency in the air environment.
Example 2
The preparation method of the resonant micro-channel with the contour resonance mode or the vertical electric field lamb wave resonance mode comprises the following steps:
step 1): depositing a lower electrode of the electrode on the silicon substrate and patterning the lower electrode, as shown in 2 a;
step 2): depositing a first layer of piezoelectric material as an active piezoelectric layer over the lower electrode, as shown in fig. 2 b;
step 3): depositing metal over the active piezoelectric layer and patterning as an upper electrode, as shown in fig. 2 c;
step 4): depositing and patterning a sacrificial layer over the upper electrode, as shown in FIG. 2 d;
step 5): depositing a second layer of piezoelectric material as a structural piezoelectric layer over the sacrificial layer, as shown in figure 2 e;
step 6): etching the structural piezoelectric layer to form a through hole connecting the upper electrode, as shown in fig. 2 f;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer, as shown in fig. 2 g;
step 8): etching the sacrificial layer by using isotropic etching to form a cavity between the active piezoelectric layer and the structural piezoelectric layer, as shown in fig. 2 h;
step 9): depositing a filling material, and filling the groove for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer, as shown in fig. 2 i;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole for connecting the lower electrode, as shown in fig. 2 j;
step 11): and etching the structural piezoelectric layer and the active piezoelectric layer, defining the boundary of the device region, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel, namely obtaining the resonance micro-channel using the contour resonance mode or the vertical electric field lamb wave resonance mode, as shown in figure 2 k.
Example 3
The preparation method of the piezoelectric micro-channel with the surface wave resonance mode comprises the following steps:
step 1): depositing a first layer of piezoelectric material as an active piezoelectric layer over a substrate, as shown in figure 3 a;
step 2): depositing metal over the active piezoelectric layer and patterning as an upper electrode, as shown in fig. 3 b;
step 3): depositing and patterning a sacrificial layer over the upper electrode, as shown in FIG. 3 c;
step 4): depositing a second layer of piezoelectric material as a structural piezoelectric layer over the sacrificial layer, as shown in figure 3 d;
step 5): etching the structural piezoelectric layer to form a through hole connected with the upper electrode, as shown in fig. 3 e;
step 6): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer, as shown in fig. 3 f;
step 7): etching the sacrificial layer using isotropic etching, the cavity between the active piezoelectric layer and the structural piezoelectric layer, as shown in fig. 3 g;
step 8): depositing a filling material, and filling the groove for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer, as shown in fig. 3 h;
step 9): and etching the structural piezoelectric layer and the active piezoelectric layer, and defining the boundary of the device area, namely obtaining the resonant micro-channel using the surface wave resonant mode, as shown in fig. 3 i.
Example 4
The preparation method of the piezoelectric micro-channel with the transverse electric field lamb wave resonance mode comprises the following steps:
step 1): depositing a flat lower electrode of the electrode on the silicon substrate, as shown in fig. 4 a;
step 2): depositing a first layer of piezoelectric material as an active piezoelectric layer over the lower electrode, as shown in fig. 4 b;
step 3): depositing metal over the active piezoelectric layer and patterning as an upper electrode, as shown in fig. 4 c;
step 4): depositing and patterning a sacrificial layer over the upper electrode, as shown in FIG. 4 d;
step 5): depositing a second layer of piezoelectric material as a structural piezoelectric layer over the sacrificial layer, as shown in figure 4 e;
step 6): etching the structural piezoelectric layer to form a through hole connecting the upper electrode, as shown in fig. 4 f;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer, as shown in fig. 4 g;
step 8): etching the sacrificial layer using isotropic etching, the cavity between the active piezoelectric layer and the structural piezoelectric layer, as shown in fig. 4 h;
step 9): depositing a filling material, and filling the groove for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer, as shown in fig. 4 i;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole (optional) for connecting the flat lower electrode, as shown in fig. 4 j;
step 11): and etching the structural piezoelectric layer and the active piezoelectric layer, defining the boundary of the device area, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel. Namely, the resonant micro channel using the transverse electric field lamb wave resonant mode is obtained, as shown in fig. 4 k.
Example 5
The preparation method given in example 2 can be used to select a piezoelectric microchannel in which the planar upper electrode and the planar lower electrode are patterned in the deposited lower electrode and the deposited upper electrode, and a piezoelectric microchannel of a vertical bulk acoustic wave resonance mode is formed, as shown in fig. 5 a.
Example 6
The preparation methods given in examples 2 to 5 may all select to deposit a protective layer in the step of depositing the patterned upper electrode, as shown in fig. 6a, the protective layer is made of a dielectric material such as silicon dioxide.
Claims (10)
1. A piezoelectric resonant microchannel for fluid detection, comprising:
the active piezoelectric layer (7) is fixed on the silicon substrate (12), the active piezoelectric layer (7) is used for fixing electrodes, the electrodes are used for exciting a resonance mode, and the root parts of the electrodes with the same polarity are communicated with each other;
a structural piezoelectric layer (14) positioned above the active piezoelectric layer (7), wherein a cavity (18) formed by a sacrificial layer process is arranged between the active piezoelectric layer (7) and the structural piezoelectric layer (14) or is directly connected with the active piezoelectric layer, and the active piezoelectric layer (7), the cavity (18) and the structural piezoelectric layer (14) are combined to form a resonant micro-channel structure;
the through hole I (5) and the through hole II (9) are respectively used for leading out the upper electrode and the lower electrode;
the first etching hole (17a) and the second etching hole (17b) are positioned on the structural piezoelectric layer (14), and the first etching hole (17a) and the second etching hole (17b) are used for defining the boundary of a device region and providing an etching groove for forming the cavity (13);
a first filling layer (8a) and a second filling layer (8b) which are used for filling the grooves used for etching the sacrificial layer so as to seal the cavity (18) between the active piezoelectric layer (7) and the structural piezoelectric layer (14);
through holes (19a, 19b) through which the test agent is injected into the resonant micro flow channel structure.
2. A piezoelectric resonant micro flow channel for liquid detection according to claim 1, wherein the structural piezoelectric layer (14) is fixed on the silicon substrate (12) as a resonant body, the active piezoelectric layer (7) has a plurality of resonance periods in a transverse section, and the electrodes are used for resonance by a piezoelectric effect resonator.
3. A piezoelectric resonant micro flow channel for liquid detection according to claim 1, wherein the electrodes are arranged in 4 different ways according to the resonance mode of driving: using a surface wave resonance mode, wherein electrodes above the active piezoelectric layer (7) are interdigital electrodes, and no electrode is arranged below the active piezoelectric layer (7); using a profile resonance mode or a vertical electric field lamb wave resonance mode, wherein an upper electrode of the active piezoelectric layer (7) is an interdigital electrode, and a lower electrode is also an interdigital electrode; using a transverse electric field lamb wave resonance mode, wherein an upper electrode of the active piezoelectric layer (7) is an interdigital electrode, and a lower electrode is a flat plate electrode; and a vertical bulk acoustic wave resonance mode is used, and an upper electrode of the active piezoelectric layer (7) is a flat plate electrode, and a lower electrode of the active piezoelectric layer is also a flat plate electrode.
4. A piezoelectric resonant micro flow channel for liquid detection according to claim 3, wherein the active piezoelectric layer (7) is connected to the silicon substrate (12) through the cavity (13) or directly using the surface wave resonance mode; when the contour resonance mode, the vertical electric field lamb wave resonance mode, the transverse electric field lamb wave resonance mode or the vertical bulk acoustic wave resonance mode is used, the active piezoelectric layer (7) is connected with the silicon substrate (12) through the cavity (13), and the device area is suspended, so that the acoustic wave is reflected at the interface of the piezoelectric material and the air.
5. The piezoelectric resonant micro flow channel for liquid detection according to claim 1, wherein the material of the active piezoelectric layer (7) and the structural piezoelectric layer (14) is aluminum nitride, lithium niobate, lithium tantalate, lead zirconate titanate; the electrode is made of metal materials.
6. The piezoelectric resonant micro flow channel for liquid detection according to claim 1, wherein the material of the electrodes is aluminum, gold, platinum, molybdenum, copper or tungsten.
7. The method of producing a resonant micro flow channel according to any one of claims 1 to 6 using a profile resonance mode or a vertical electric field lamb wave resonance mode, comprising the steps of:
step 1): depositing a lower electrode of the electrode on the silicon substrate and patterning the lower electrode;
step 2): depositing a first layer of piezoelectric material over the lower electrode as an active piezoelectric layer;
step 3): depositing a metal over the active piezoelectric layer and patterning into an upper electrode;
step 4): depositing and patterning a sacrificial layer over the upper electrode;
step 5): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 6): etching the structural piezoelectric layer to form a through hole connected with the upper electrode;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 8): etching the sacrificial layer by using isotropic etching to form a cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 9): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole connected with the lower electrode;
step 11): and etching the structural piezoelectric layer and the active piezoelectric layer, defining the boundary of the device region, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel, namely obtaining the resonance micro-channel using the contour resonance mode or the vertical electric field lamb wave resonance mode.
8. The method of preparing a resonant micro flow channel as claimed in any one of claims 1 to 6 using a surface wave resonance mode, comprising the steps of:
step 1): depositing a first layer of piezoelectric material over a substrate as an active piezoelectric layer;
step 2): depositing a metal over the active piezoelectric layer and patterning into an upper electrode;
step 3): depositing and patterning a sacrificial layer over the upper electrode;
step 4): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 5): etching the structural piezoelectric layer to form a through hole connected with the upper electrode;
step 6): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 7): etching the sacrificial layer by using isotropic etching, wherein the cavity is formed between the active piezoelectric layer and the structural piezoelectric layer;
step 8): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer, so as to obtain the resonant micro-channel using the surface wave resonant mode.
9. The method of preparing a resonant micro flow channel according to any one of claims 1 to 6 using a transverse electric field lamb wave resonance mode, comprising the steps of:
step 1): depositing a flat lower electrode of the electrode on the silicon substrate;
step 2): depositing a first layer of piezoelectric material over the lower electrode as an active piezoelectric layer;
step 3): depositing a metal over the active piezoelectric layer and patterning into an upper electrode;
step 4): depositing and patterning a sacrificial layer over the upper electrode;
step 5): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 6): etching the structural piezoelectric layer to form a through hole connected with the upper electrode;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 8): etching the sacrificial layer by using isotropic etching, wherein the cavity is formed between the active piezoelectric layer and the structural piezoelectric layer;
step 9): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole connected with the lower electrode of the flat plate;
step 11): and etching the piezoelectric layer and the active piezoelectric layer of the structure, defining the boundary of the device area, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel, namely obtaining the resonance micro-channel using the transverse electric field lamb wave resonance mode.
10. The method of preparing a resonant micro flow channel according to any one of claims 1 to 6 using a vertical bulk acoustic wave resonance mode, comprising the steps of
Step 1): depositing a lower electrode of the electrode on the silicon substrate and patterning the flat lower electrode;
step 2): depositing a first layer of piezoelectric material over the lower electrode as an active piezoelectric layer;
step 3): depositing metal above the active piezoelectric layer and patterning the metal into a flat upper electrode;
step 4): depositing and patterning a sacrificial layer over the upper electrode;
step 5): depositing a second piezoelectric material as a structural piezoelectric layer over the sacrificial layer;
step 6): etching the structural piezoelectric layer to form a through hole connected with the upper electrode of the flat plate;
step 7): etching the structural piezoelectric layer to form a groove for etching the sacrificial layer;
step 8): etching the sacrificial layer by using isotropic etching, wherein the cavity is formed between the active piezoelectric layer and the structural piezoelectric layer;
step 9): depositing a filling material, and filling the groove used for etching the sacrificial layer to seal the cavity between the active piezoelectric layer and the structural piezoelectric layer;
step 10): etching the structural piezoelectric layer and the active piezoelectric layer to form a through hole connected with the lower electrode of the flat plate;
step 11): and etching the piezoelectric layer and the active piezoelectric layer of the structure, defining the boundary of the device area, and etching the silicon substrate by using isotropic etching to form a cavity below the piezoelectric resonance micro-channel, namely obtaining the resonance micro-channel using the vertical bulk acoustic wave resonance mode.
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| US20020189062A1 (en) * | 2001-06-15 | 2002-12-19 | Asia Pacific Microsystems, Inc. | Manufacturing method for a high quality film bulk acoustic wave device |
| CN109374194A (en) * | 2018-11-22 | 2019-02-22 | 华中科技大学 | A kind of adjustable pliable pressure sensor array of reference pressure and preparation method thereof |
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