CN111796119B - Resonant acceleration sensor based on nano piezoelectric beam and preparation method thereof - Google Patents
Resonant acceleration sensor based on nano piezoelectric beam and preparation method thereof Download PDFInfo
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- CN111796119B CN111796119B CN202010699338.6A CN202010699338A CN111796119B CN 111796119 B CN111796119 B CN 111796119B CN 202010699338 A CN202010699338 A CN 202010699338A CN 111796119 B CN111796119 B CN 111796119B
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- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P15/00—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
- G01P15/02—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses
- G01P15/08—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values
- G01P15/097—Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration by making use of inertia forces using solid seismic masses with conversion into electric or magnetic values by vibratory elements
Abstract
The invention belongs to the technical field of micro-electronic machinery, and particularly relates to a resonant acceleration sensor based on a nano piezoelectric beam and a preparation method thereof. The device comprises a substrate, a detection structure layer and a cover plate; the detection structure layer is manufactured on the basis of a square double-polished silicon wafer and comprises a square outer frame and a square sensitive mass block positioned in the center of the outer frame, two sides of the sensitive mass block in the x-axis direction are respectively connected with corresponding inner side walls of the outer frame through supporting beams, two sides of the sensitive mass block in the y-axis direction are respectively contacted with corresponding inner side walls of the outer frame through double-ended tuning fork resonators, and each double-ended tuning fork resonator comprises a pair of zinc oxide resonant beams; the top surface of the detection structure layer and the bottom surface of the cover plate, and the bottom surface of the detection structure layer and the top surface of the base are connected through key grooves, so that the base, the detection structure layer and the cover plate form an acceleration sensor with an inner part sealed. The acceleration sensor has high structural sensitivity, and can realize the indexes of strong overload resistance, high resonance frequency and high sensitivity.
Description
Technical Field
The invention belongs to the technical field of micro-electronic machinery, relates to a micro-inertial sensor, and particularly relates to a resonant acceleration sensor based on a nano piezoelectric beam and a preparation method thereof.
Background
The acceleration sensor is an inertia device in an inertia guidance system, takes charge of providing an inertia measurement reference for missile flight, measuring the acceleration and the flight attitude angle of the missile in real time and the like, and participates in the attitude control and guidance control of the missile. In the future, missile guidance modes are mainly inertial guidance. The advantages of inertial guidance are: the missile does not need any external information, and has good concealment, strong anti-interference performance, long missile range and high guidance precision. However, the missile is interfered by various factors during the flight process, so that deviation of the trajectory is easily caused, the missile cannot accurately attack a set target, failure of strategic reservation planning is caused, and national strategic resources are wasted. Therefore, the acceleration sensor is a core device of the inertial system, and the technical indexes of the acceleration sensor directly influence the overall performance of the inertial navigation system, so that the problem that the acceleration sensor for high-precision navigation and guidance needs to be solved urgently in China is solved.
To date, micromechanical resonant acceleration sensors based on MEMS (micro-electro-mechanical systems) technology have had the following problems: 1. although medium and low precision resonant acceleration sensors are mature day by day at home and abroad, along with the fact that resonant acceleration sensors are applied to inertial navigation and guidance more and more widely, high-precision and low-range acceleration sensors are urgently needed; 2. in the driving detection mode of the resonant beam structure, the electrostatic driving detection mode is mostly adopted at home and abroad, the driving detection mode has larger influence on the contact loss and the temperature of the double-end clamped beam on the frequency of the resonant beam, and the quality factor of the acceleration sensor and the precision of a closed-loop control circuit are reduced; 3. the mismatch of the thermal expansion coefficients of the resonator material and the substrate material can introduce thermal stress into the resonant structure, affect the resonant frequency, and cause the failure of the acceleration sensor or the great reduction of the performance. Most research units at present adopt silicon as a resonator material, so that the resonance frequency of the acceleration sensor is low, the silicon has no piezoelectric property, and the vibration of the resonator needs to be excited by means of various means such as electrostatic force, thermal expansion force, electromagnetic force and the like, so that the mechanical coupling of the acceleration sensor is increased, noise interference is easily introduced, and the precision of the acceleration sensor is limited to be further improved; 4. at present, the engineering progress of the silicon micromechanical resonance acceleration sensor in China is slow, and the problems of complex process conditions, large structural dimension error and high cost caused by difficult control of finished product rate exist.
Disclosure of Invention
In order to avoid the defects of the prior art, the invention provides a resonant acceleration sensor based on a zinc oxide nano piezoelectric beam and a preparation method thereof, which solve the technical problems of poor overload resistance, low resonant frequency and low sensitivity of the traditional resonant acceleration sensor in the prior art by adopting a nano-scale resonant beam, realizing distributed differential detection in an up-and-down symmetrical distribution mode and supporting beams at two ends. The specific technical scheme is as follows:
the resonant acceleration sensor based on the nano piezoelectric beam comprises a substrate 1, a detection structure layer 2 and a cover plate 3;
the substrate 1 is manufactured on the basis of a <100> crystal orientation N-type single polished silicon wafer, the top surface of the substrate 1 is a polished surface, a movable cavity groove 11 is formed in the top surface, and a lower limiting groove 12 is formed in the center of the bottom surface of the movable cavity groove 11;
the detection structure layer 2 is made on the basis of a square double-polished SOI silicon chip and comprises a square outer frame 21 and a square sensitive mass block 22 positioned in the center of the outer frame 21, and an upper limiting column 231 and a lower limiting column 211 are respectively arranged in the centers of the top surface and the bottom surface of the sensitive mass block 22;
the center of the sensing mass block 22 is an origin, two sides of the sensing mass block 22 in the x-axis direction are respectively connected with the inner side walls of the corresponding outer frames 21 through the supporting beams 23, two sides of the sensing mass block 22 in the y-axis direction are respectively connected with the inner side walls of the corresponding outer frames 21 through the double-ended tuning fork resonators 24, and each double-ended tuning fork resonator 24 comprises a pair of zinc oxide resonant beams 241; the cover plate 3 is manufactured on the basis of a <100> crystal orientation N-type single polished silicon wafer, the bottom surface of the cover plate 3 is a polished surface, an upper limiting groove 32 is formed in the center of the polished surface, and metal electrodes 242, corresponding to two ends of each double-end tuning fork resonator 24, of the cover plate 3 are respectively provided with a wiring leading-out hole 31 in a penetrating mode;
the top surface of the detection structure layer 2 and the bottom surface of the cover plate 3 form a key groove connection through the matching of the upper limiting column 231 and the upper limiting groove 32, and the bottom surface of the detection structure layer 2 and the top surface of the substrate 1 form a key groove connection through the matching of the lower limiting column 211 and the lower limiting groove 12, so that the substrate 1, the detection structure layer 2 and the cover plate 3 form an acceleration sensor with an inner closed part.
Further, mounting grooves are formed in the middle portions of the two sides of the sensing mass block 22 in the x-axis direction and the middle portions of the two sides of the sensing mass block in the y-axis direction.
Further, the damping coefficient clearance between the upper limiting column 231 and the upper limiting groove 32 in the Y axis direction and the damping coefficient clearance between the lower limiting column 211 and the lower limiting groove 12 in the Y axis direction are both 1 um.
The invention also comprises a preparation method of the resonant acceleration sensor based on the nano piezoelectric beam, which comprises the following steps:
preparing tablets: taking a double-polished SOI silicon chip with the thickness of 100 mu m and two <100> crystal orientation N-type single-polished silicon chips with the thickness of 30 mu m;
primary photoetching: cleaning the double-polished SOI silicon wafer by using a standard semiconductor cleaning process, and spin-coating photoresist on the surface of the double-polished SOI silicon wafer, exposing the outer frame 21 and the sensitive mass block 22 by photoetching, and respectively photoetching a groove in the middle of each side edge of the sensitive mass block 22;
secondary photoetching: heating the top surface of the double-polished SOI silicon wafer at a high temperature to grow a layer of silicon dioxide on the top surface, attaching a layer of positive photoresist on the surface of the silicon dioxide, photoetching the silicon dioxide under a first layer of mask plate, washing the photoresist after completing photoetching, etching the silicon dioxide by adopting a wet method, and respectively forming an insulating layer (namely a silicon dioxide layer 243) with the thickness of 0.2 mu m on the surface of the groove in the Y-axis direction corresponding to the sensitive mass block and the side wall of the square frame;
and (3) carrying out third photoetching: depositing zinc oxide on the surface of the groove in the Y-axis direction in a reactive sputtering mode, then covering a layer of positive photoresist on the surface of the zinc oxide, photoetching the zinc oxide under a second layer of mask plate, washing the photoresist after photoetching, and etching the zinc oxide by a wet method to form a zinc oxide piezoelectric layer with the thickness of 500nm between the silicon dioxide layers 243 on the surface of the groove in each Y-axis direction and form a pair of zinc oxide resonant beams 241;
and (3) depositing an electrode: respectively depositing metal electrodes 242 on the surface of the silicon dioxide layer 243, namely two ends of the pair of zinc oxide resonance beams 241, by using an electron beam deposition method, wherein the thickness of the metal electrodes is 0.1 mu m;
four times of photoetching: after the substrate of the double-polished SOI silicon chip is integrally thinned by 30 micrometers, etching the lower silicon layer by a reactive ion etching method until an outer frame 21 and a sensitive mass block 22 which are independent of each other are released, and etching grooves in the y-axis direction and the x-axis direction of the sensitive mass block 22 by a deep reactive ion etching method, so that the grooves corresponding to the y-axis direction are respectively released to form a double-end tuning fork resonator 24, and the grooves corresponding to the x-axis direction are respectively released to form a support beam 23; five times of photoetching: photoetching and etching a lower limiting column with the side length of 30 mu m and the height of 8 mu m at the center of the bottom surface of the sensitive mass block 22;
and (3) six times of photoetching: a first movable cavity groove 11 with the depth of 5 microns is photoetched on the polished surface of a <100> crystal orientation N-type single polished silicon wafer with the thickness of 30 microns, and a lower limiting groove 12 with the side length of 30 microns and the height of 5 microns is photoetched at the center of the movable cavity groove 11, so that the substrate 1 is integrally formed;
primary silicon-silicon bonding: respectively cleaning the external surfaces of the double-polished SOI silicon chip and the substrate 1 formed by processing, and then carrying out
Surface activation treatment; rapidly attaching the polished surface of the top surface of the substrate 1 and the bottom surface of the detection structure layer 2 together at room temperature to enable the lower limit groove 12 and the lower limit 211 column to be mutually adapted, and putting the lower limit groove 12 and the lower limit groove together into a pure oxygen environment for high-temperature annealing treatment until bonding and integration are formed, thus completing the bonding process;
and (4) carrying out seven times of photoetching: photoetching the center of the top surface of the bonded silicon wafer to form an upper limiting column 231 with the side length of 30 microns and the height of 10 microns;
and (4) carrying out photoetching eight times: taking a second 30-micron-thickness <100> crystal orientation N-type single polished silicon wafer, photoetching an upper limiting groove 32 with the side length of 30 microns and the depth of 10 microns at the center of an upper polished surface, and integrally forming a cover plate 3;
secondary silicon-silicon bonding: cleaning the silicon wafer of the primary silicon-silicon bonding molding and the silicon wafer of the cover plate 3, and then carrying out surface activation treatment; rapidly attaching the polished surface of the bottom surface of the cover plate 3 to the top surface of the detection structure layer 2 at room temperature, enabling the upper limiting groove 32 and the upper limiting column 231 to be matched with each other, and putting the upper limiting groove and the upper limiting column together into a pure oxygen environment for high-temperature annealing treatment until bonding and integration are achieved, namely, the bonding process is completed;
and the metal electrodes 242 corresponding to the two ends of each double-ended tuning fork resonator 24 on the cover plate 3 are respectively provided with a wiring leading-out hole 31 in a penetrating way, and the wiring leading-out holes 31 are filled with metal copper.
Further, the solution adopted by the primary silicon-silicon bonding and surface activation treatment is a hydroxide ion solution or a plasma solution.
Further, the secondary silicon-silicon bonding is to complete the sealing and packaging of the bonding among the substrate 1, the cover plate 3 and the detection structure layer 2 by using glass slurry.
The beneficial technical effects of the invention are embodied in the following aspects:
1. the invention adopts zinc oxide as the material of the resonant beam, so that the resonant beam can keep good piezoelectric property under some extreme environments, the resonator has high resonant frequency, and a piezoelectric excitation detection mode is adopted, thereby reducing the mechanical coupling of the acceleration sensor, reducing the interference of noise and greatly improving the precision of the acceleration sensor.
2. The acceleration sensor is analyzed and verified based on a simulation platform, the resonant frequency of the working mode of one double-end tuning fork resonator is 2.98793MHz, and the resonant frequency of the working mode of the other double-end tuning fork resonator is 2.987288 MHz; under the action of 2000g acceleration load, the maximum stress of the acceleration sensor is 241.46MPa, which is far less than the ultimate strength of silicon and zinc oxide; within the design range of +/-10 g, the structural sensitivity of the acceleration sensor is up to 1.13311 KHz/g; the technical indexes of the traditional resonant acceleration sensor are broken through, and the indexes of strong overload resistance, high resonant frequency and high sensitivity are realized.
3. The acceleration sensor realizes symmetrical distribution and differential detection, so that the sensitivity can be doubled, and the influence of temperature common mode error can be reduced; the support beams are distributed in a bilateral symmetry mode, so that the cross sensitivity of the acceleration sensor can be effectively reduced, and the anti-interference capability is enhanced.
4. According to the acceleration sensing device, the double-end tuning fork resonators are uniformly distributed in the middle of two sides of the sensitive mass block of the acceleration sensing device in the y-axis direction, each double-end tuning fork resonator comprises a pair of zinc oxide resonant beams, the two double-end tuning fork resonators are far distributed in the two-side distribution mode, the mutual coupling phenomenon is small through front harmonic response analysis, and the acceleration sensing device has the characteristics of simple structure and miniaturization.
5. According to the acceleration sensor manufacturing method, one double-polished SOI silicon wafer and two <100> crystal orientation N-type single-polished silicon wafers are obtained through a multi-step process, only three layers of mask plates are needed, the process flow is simple and reliable, and the yield is high.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
Fig. 2 is a schematic general cross-sectional view of the present invention.
FIG. 3 is a schematic structural diagram of a detection structure layer according to the present invention.
Fig. 4 is a schematic structural diagram of the cover plate of the present invention.
FIG. 5 is a schematic cross-sectional view of a single photolithography process of the present invention.
FIG. 6 is a schematic cross-sectional view of a second photolithography process according to the present invention.
FIG. 7 is a schematic cross-sectional view of a triple photolithography process according to the present invention.
FIG. 8 is a cross-sectional view of a metal electrode forming process according to the present invention.
FIG. 9 is a schematic cross-sectional view of a four-step photolithography process according to the present invention.
FIG. 10 is a schematic cross-sectional view of five photolithography processes according to the present invention.
FIG. 11 is a schematic cross-sectional view of a six-pass photolithography process according to the present invention.
FIG. 12 is a cross-sectional view of a one-step silicon-silicon bonding process of the present invention.
FIG. 13 is a schematic cross-sectional view of a seven-pass photolithography process according to the present invention.
FIG. 14 is a schematic cross-sectional view of an eight-pass photolithography process according to the present invention.
FIG. 15 is a schematic cross-sectional view of a secondary silicon-silicon bonding process of the present invention.
FIG. 16 is a cross-sectional view of the process of forming wire holes in the cover plate according to the present invention.
Wherein: the device comprises a substrate 1, a movable cavity groove 11, a lower limiting groove 12, a 2 detection structure layer, a 211 lower limiting column, a 231 upper limiting column, a 3 cover plate, a 31 wiring leading-out hole, a 32 upper limiting groove, a 21 outer frame, a 22 sensitive mass block, a 23 supporting beam, a 24 double-ended tuning fork resonator, a 241 pair of zinc oxide resonant beams, 242 metal electrodes and 243 silicon dioxide layers.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the detailed description and specific examples, while indicating the invention,
and are not intended to limit the invention.
Example 1
As shown in fig. 1 to 4, the resonant acceleration sensor based on the nano piezoelectric beam includes a substrate 1, a detection structure layer 2 and a cover plate 3;
the substrate 1 is manufactured on the basis of a <100> crystal orientation N-type single polished silicon wafer, the top surface of the substrate 1 is a polished surface, a movable cavity groove 11 is formed in the top surface, and a lower limiting groove 12 is formed in the center of the movable cavity groove 11;
the detection structure layer 2 is made on the basis of a square double-polished SOI silicon chip and comprises a square outer frame 21 and a square sensitive mass block 22 positioned in the center of the outer frame 21, and an upper limiting column 231 and a lower limiting column 211 are respectively arranged in the centers of the top surface and the bottom surface of the sensitive mass block 22;
with the center of the sensing mass block 22 as an origin, two sides of the sensing mass block 22 in the x-axis direction are respectively connected with the inner side walls of the corresponding outer frame 21 through the supporting beams 23, two sides of the sensing mass block 22 in the y-axis direction are respectively contacted with the inner side walls of the corresponding outer frame 21 through the double-ended tuning fork resonators 24, and each double-ended tuning fork resonator 24 comprises a pair of zinc oxide resonant beams 241; the cover plate 3 is manufactured on the basis of a <100> crystal orientation N-type single polished silicon wafer, the bottom surface of the cover plate 3 is a polished surface, an upper limiting groove 32 is formed in the center of the polished surface, and metal electrodes 242, corresponding to two ends of each double-end tuning fork resonator 24, of the cover plate 3 penetrate through the two ends of each double-end tuning fork resonator 24 to form wiring leading-out holes 31 respectively;
the top surface of the detection structure layer 2 and the bottom surface of the cover plate 3 form a key groove connection through the matching of the upper limiting column 231 and the upper limiting groove 32, and the bottom surface of the detection structure layer 2 and the top surface of the substrate 1 form a key groove connection through the matching of the lower limiting column 211 and the lower limiting groove 12, so that the substrate 1, the detection structure layer 2 and the cover plate 3 form an acceleration sensor with an inner closed part.
And mounting grooves are formed in the middle parts of the two sides of the sensitive mass block 22 in the x-axis direction and the middle parts of the two sides of the sensitive mass block in the y-axis direction.
The damping coefficient clearance of the upper limiting column 231 and the upper limiting groove 32 in the Y-axis direction and the damping coefficient clearance of the lower limiting column 211 and the lower limiting groove 12 in the Y-axis direction are both 1 um.
Example 2
The invention also comprises a preparation method of the resonant acceleration sensor based on the nano piezoelectric beam, which comprises the following steps: preparing tablets: taking a double-polished SOI silicon chip with the thickness of 100 mu m and two <100> crystal orientation N-type single-polished silicon chips with the thickness of 30 mu m;
primary photoetching: cleaning the double-polished SOI silicon wafer by using a standard semiconductor cleaning process, and spin-coating photoresist on the surface of the double-polished SOI silicon wafer, exposing the outer frame 21 and the sensitive mass block 22 by photoetching, and respectively photoetching a groove in the middle of each side edge of the sensitive mass block 22; as shown in fig. 5.
Secondary photoetching: heating the top surface of the double-polished SOI silicon wafer at a high temperature to grow a layer of silicon dioxide on the top surface, attaching a layer of positive photoresist on the surface of the silicon dioxide, photoetching the silicon dioxide under a first layer of mask plate, washing the photoresist after completing photoetching, etching the silicon dioxide by adopting a wet method, and respectively forming an insulating layer (namely a silicon dioxide layer 243) with the thickness of 0.2 mu m on the surface of the groove in the Y-axis direction corresponding to the inner side walls of the sensitive mass block 22 and the outer frame 21; as shown in fig. 6.
And (3) carrying out third photoetching: depositing zinc oxide on the surface of the silicon dioxide layer 243 by adopting a reactive sputtering mode, then covering a layer of positive photoresist on the surface of the zinc oxide, and placing the zinc oxide under a second layer of mask for photoetching, washing the photoresist after completing photoetching, and then etching the zinc oxide by a wet method to form a zinc oxide piezoelectric layer with the thickness of 500nm between the silicon dioxide layers 243 on the surface of each groove in the Y-axis direction, thereby forming a pair of zinc oxide resonant beams 241; as shown in fig. 7. And (3) depositing an electrode: respectively depositing metal electrodes 242 on the surface of the silicon dioxide layer 243, namely two ends of the pair of zinc oxide resonance beams 241, by using an electron beam deposition method, wherein the thickness of the metal electrodes is 0.1 mu m; as shown in fig. 8.
Four times of photoetching: after the substrate of the double-polished SOI silicon chip is integrally thinned by 30 micrometers, etching the lower silicon layer by a reactive ion etching method until an outer frame 21 and a sensitive mass block 22 which are independent of each other are released, and etching grooves in the y-axis direction and the x-axis direction of the sensitive mass block 22 by a deep reactive ion etching method, so that the grooves corresponding to the y-axis direction are respectively released to form a double-end tuning fork resonator 24, and the grooves corresponding to the x-axis direction are respectively released to form a support beam 23, as shown in FIG. 9; wherein the support beam 23 is etched using a backside vertical etch-deep reactive ion etching system, not shown. Five times of photoetching: photoetching and etching a lower limiting column with the side length of 30 mu m and the height of 8 mu m at the center of the bottom surface of the sensitive mass block 22; as shown in fig. 10.
And (3) six times of photoetching: a first movable cavity groove 11 with the depth of 5 microns is photoetched on the polished surface of a <100> crystal orientation N-type single polished silicon wafer with the thickness of 30 microns, and a lower limiting groove 12 with the side length of 30 microns and the height of 5 microns is photoetched at the center of the movable cavity groove 11, so that the substrate 1 is integrally formed; as shown in fig. 11.
Primary silicon-silicon bonding: respectively cleaning the outer surfaces of the double-polished SOI silicon chip and the substrate 1 formed by processing, and then carrying out surface activation treatment; the solution adopted for surface activation treatment is hydroxide ion solution or plasma solution;
rapidly attaching the polished surface of the top surface of the substrate 1 and the bottom surface of the detection structure layer 2 together at room temperature, enabling the lower limiting groove 12 and the lower limiting 211 column to be matched with each other, and putting the lower limiting groove 12 and the lower limiting 211 column together into a pure oxygen environment for high-temperature annealing treatment until bonding and integration are formed, namely, completing a bonding process; as shown in fig. 12.
And (4) carrying out seven times of photoetching: photoetching the center of the top surface of the bonded silicon wafer to form an upper limiting column 231 with the side length of 30 microns and the height of 10 microns; as shown in fig. 13.
And (4) carrying out photoetching eight times: taking a second 30-micron-thickness <100> crystal orientation N-type single polished silicon wafer, photoetching an upper limiting groove 32 with the side length of 30 microns and the depth of 10 microns at the center of an upper polished surface, and integrally forming a cover plate 3; as shown in fig. 14. Secondary silicon-silicon bonding: cleaning the silicon wafer of the primary silicon-silicon bonding molding and the silicon wafer of the cover plate 3, and then carrying out surface activation treatment; rapidly attaching the polished surface of the bottom surface of the cover plate 3 to the top surface of the detection structure layer 2 at room temperature, enabling the upper limiting groove 32 and the upper limiting column 231 to be matched with each other, and putting the upper limiting groove and the upper limiting column together into a pure oxygen environment for high-temperature annealing treatment until bonding and integration are achieved, namely, the bonding process is completed; as shown in fig. 15.
And the metal electrodes 242 corresponding to the two ends of each double-ended tuning fork resonator 24 on the cover plate 3 are respectively provided with a wiring leading-out hole 31 in a penetrating way, and the wiring leading-out holes 31 are filled with metal copper, as shown in fig. 16.
Wherein, the primary silicon-silicon bonding and the secondary silicon-silicon bonding are all completed by adopting glass slurry to realize the closed encapsulation of bonding among the substrate 1, the cover plate 3 and the detection structure layer 2.
The working principle and the simulation process of the invention are as follows:
the two double-ended tuning fork resonators 24 with the same size are symmetrically distributed in the y-axis direction of the sensing mass block 22, the sensing mass block 22 converts an acceleration signal into an equivalent inertia force under the action of acceleration, and the equivalent inertia force is transmitted to the double-ended tuning fork resonators 24, so that the frequencies of a pair of resonance beams 241 of the double-ended tuning fork resonators 24 are changed, and an acceleration value can be obtained by detecting the resonance frequency variation.
In order to reduce interference and improve measurement accuracy, the two double-ended tuning fork resonators 24 symmetrically distributed in the y-axis direction of the sensing mass 22 are structured such that when acceleration is input, the resonant frequency of the stretched double-ended tuning fork resonator 24 is increased, and the resonant frequency of the compressed double-ended tuning fork resonator 24 is decreased. The change quantity of the resonant frequency, namely the differential frequency, can be obtained through the difference frequency detection scheme, and then the magnitude of the external acceleration load is deduced. Within a certain input acceleration range, the differential frequency of the input acceleration sensor is approximately linear to the input acceleration value.
The acceleration sensor is analyzed and verified based on a simulation platform. The resonant frequency of the working mode of one double-end tuning fork resonator is 2.98793MHz, and the resonant frequency of the working mode of the other double-end tuning fork resonator is 2.987288 MHz; under the action of 2000g acceleration load, the maximum stress of the acceleration sensor is 241.46MPa, which is far less than the ultimate strength of silicon and zinc oxide; within the design range of +/-10 g, the structural sensitivity of the acceleration sensor is up to 1.13311 KHz/g; the technical indexes of the traditional resonant acceleration sensor are broken through, and the indexes of strong overload resistance, high resonant frequency and high sensitivity are realized.
In summary, the resonant acceleration sensor based on the zinc oxide nano piezoelectric beam provided by the invention adopts zinc oxide as the piezoelectric material, so that the sensor can keep good piezoelectric property in some extreme environments and the double-ended tuning fork resonator 24 has high resonant frequency; the symmetrical distribution of the two double-end tuning fork resonators 24 in the y-axis direction of the sensitive mass block 22 realizes the differential detection, which not only can double the sensitivity, but also can reduce the influence of temperature common mode error; the two symmetrical supporting beams 23 in the x-axis direction of the sensitive mass block 22 can effectively reduce the cross sensitivity of the acceleration sensor of the invention and enhance the anti-interference capability.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (5)
1. A method for preparing a resonant acceleration sensor based on a nano piezoelectric beam is characterized by comprising the following steps:
preparing tablets: taking a double-polished SOI silicon chip with the thickness of 100 mu m and two <100> crystal orientation N-type single-polished silicon chips with the thickness of 30 mu m;
primary photoetching: cleaning a double-polished SOI silicon wafer by using a standard semiconductor cleaning process, spin-coating photoresist on the surface of the double-polished SOI silicon wafer, exposing an outer frame (21) and a sensitive mass block (22) by photoetching, and respectively photoetching a groove in the middle of each side edge of the sensitive mass block (22);
secondary photoetching: heating the top surface of the double-polished SOI silicon wafer at a high temperature to grow a layer of silicon dioxide on the top surface, attaching a layer of positive photoresist on the surface of the silicon dioxide, photoetching the silicon dioxide under a first layer of mask plate, washing the photoresist after completing photoetching, etching the silicon dioxide by adopting a wet method, and respectively forming an insulating layer (namely a silicon dioxide layer 243) with the thickness of 0.2 mu m on the surface of the groove in the Y-axis direction corresponding to the sensitive mass block (22) and the inner side wall of the outer frame (21);
and (3) carrying out third photoetching: depositing zinc oxide on the surface of the silicon dioxide layer (243) in a reactive sputtering mode, then covering a layer of positive photoresist on the surface of the zinc oxide, placing the zinc oxide under a second layer of mask plate for photoetching, washing the photoresist after completing photoetching, and then etching the zinc oxide by a wet method to form a zinc oxide piezoelectric layer with the thickness of 500nm between the silicon dioxide layers (243) on the surface of each groove in the Y-axis direction, thereby forming a pair of zinc oxide resonant beams (241);
and (3) depositing an electrode: respectively depositing metal electrodes (242) on the surface of the silicon dioxide layer 243, namely two ends of the pair of zinc oxide resonance beams (241) by using an electron beam deposition method, wherein the thickness of the metal electrodes is 0.1 mu m;
four times of photoetching: after the substrate of the double-polished SOI silicon chip is integrally thinned by 30 micrometers, etching the lower silicon layer by a reactive ion etching method until an outer frame (21) and a sensitive mass block (22) which are independent of each other are released, and etching grooves in the y-axis direction and the x-axis direction of the sensitive mass block (22) by a deep reactive ion etching method to respectively release the grooves corresponding to the y-axis direction to form a double-end tuning fork resonator (24) and respectively release the grooves corresponding to the x-axis direction to form a supporting beam (23);
five times of photoetching: photoetching and etching a lower limiting column with the side length of 30 mu m and the height of 8 mu m at the center of the bottom surface of the sensitive mass block (22);
and (3) six times of photoetching: a first movable cavity groove (11) with the depth of 5 mu m is photoetched on the polished surface of a <100> crystal orientation N-type single polished silicon wafer with the thickness of 30 mu m, and a lower limiting groove (12) with the side length of 30 mu m and the height of 5 mu m is photoetched at the center of the movable cavity groove (11), so that the substrate (1) is integrally formed;
primary silicon-silicon bonding: respectively cleaning the external surfaces of the double-polished SOI silicon chip and the substrate (1) formed by processing, and then carrying out
Surface activation treatment; rapidly attaching the polished surface of the top surface of the substrate (1) and the bottom surface of the detection structure layer (2) together at room temperature, enabling the lower limiting groove (12) and the lower limiting column (211) to be matched with each other, and putting the lower limiting groove and the lower limiting column together into a pure oxygen environment for high-temperature annealing treatment until bonding and integration are formed, namely, completing a bonding process;
and (4) carrying out seven times of photoetching: photoetching the center of the top surface of the bonded silicon wafer to form an upper limiting column (231) with the side length of 30 mu m and the height of 10 mu m;
and (4) carrying out photoetching eight times: taking a second 100 crystal orientation N-type single polished silicon wafer with the thickness of 30 mu m, photoetching an upper limiting groove (32) with the side length of 30 mu m and the depth of 10 mu m at the center of an upper polished surface, and integrally forming a cover plate (3);
secondary silicon-silicon bonding: cleaning the silicon wafer subjected to primary silicon-silicon bonding molding and the silicon wafer of the cover plate (3), and then performing surface activation treatment; rapidly attaching the polished surface of the bottom surface of the cover plate (3) and the top surface of the detection structure layer (2) together at room temperature, enabling the upper limiting groove (32) and the upper limiting column (231) to be mutually matched, and putting the upper limiting groove and the upper limiting column together into a pure oxygen environment for high-temperature annealing treatment until bonding and integration are formed, namely completing a bonding process;
metal electrodes (242) corresponding to two ends of each double-end tuning fork resonator (24) on the cover plate (3) are respectively provided with a wiring leading-out hole (31) in a penetrating mode, and metal copper is filled in the wiring leading-out holes (31);
the resonant acceleration sensor prepared by the method comprises a substrate (1), a detection structure layer (2) and a cover plate (3);
the substrate (1) is manufactured on the basis of a <100> crystal orientation N-type single polished silicon wafer, the top surface of the substrate (1) is a polished surface, a movable cavity groove (11) is formed in the top surface, and a lower limiting groove (12) is formed in the center of the movable cavity groove (11);
the detection structure layer (2) is manufactured on the basis of a square double-polished SOI silicon chip and comprises a square outer frame (21) and a square sensitive mass block (22) positioned in the center of the outer frame (21), and the centers of the top surface and the bottom surface of the sensitive mass block (22) are respectively provided with an upper limiting column (231) and a lower limiting column (211);
the center of the sensitive mass block (22) is an origin, two sides of the sensitive mass block (22) in the x-axis direction are respectively connected with the inner side walls of the corresponding outer frames (21) through supporting beams (23), two sides of the sensitive mass block (22) in the y-axis direction are respectively connected with the inner side walls of the corresponding outer frames (21) through double-ended tuning fork resonators (24), and each double-ended tuning fork resonator (24) comprises a pair of zinc oxide resonant beams (241);
the cover plate (3) is manufactured on the basis of a <100> crystal orientation N-type single polished silicon wafer, the bottom surface of the cover plate (3) is a polished surface, an upper limiting groove (32) is formed in the center of the polished surface, and metal electrodes (242) of the cover plate (3) corresponding to two ends of each double-end tuning fork resonator (24) are respectively provided with a wiring leading-out hole (31) in a penetrating mode;
the top surface of detecting structural layer (2) and the bottom surface of apron (3) form the keyway through the cooperation of last spacing post (231) and last spacing groove (32) and connect, the bottom surface of detecting structural layer (2) with the top surface of base (1) forms the keyway through the cooperation of lower spacing post (211) and lower spacing groove (12) and connects for base (1), detection structural layer (2) and apron (3) form inside confined acceleration sensor.
2. The method for preparing the resonant acceleration sensor based on the nano piezoelectric beam as claimed in claim 1, wherein: the solution adopted by the primary silicon-silicon bonding and surface activation treatment is as follows: a hydroxide ion solution or a plasma solution.
3. The method for preparing the resonant acceleration sensor based on the nano piezoelectric beam as claimed in claim 1, wherein: and in the secondary silicon-silicon bonding, the substrate (1), the cover plate (3) and the detection structure layer (2) are bonded and hermetically packaged by adopting glass slurry.
4. The method for preparing the resonant acceleration sensor based on the nano piezoelectric beam as claimed in claim 1, wherein: mounting grooves are formed in the middle parts of the two sides of the sensitive mass block (22) in the x-axis direction and the middle parts of the two sides of the sensitive mass block (22) in the y-axis direction.
5. The method for preparing the resonant acceleration sensor based on the nano piezoelectric beam as claimed in claim 1, wherein: the damping coefficient clearance of the upper limiting column (231) and the upper limiting groove (32) in the Y-axis direction and the damping coefficient clearance of the lower limiting column (211) and the lower limiting groove (12) in the Y-axis direction are both 1 um.
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| CN113945732A (en) * | 2021-10-18 | 2022-01-18 | 中国人民解放军国防科技大学 | Graphene double-shaft differential resonant accelerometer |
| CN114866056B (en) * | 2022-04-27 | 2023-05-12 | 中国工程物理研究院电子工程研究所 | Piezoelectric driven zinc oxide nanowire resonator |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011117944A (en) * | 2009-10-29 | 2011-06-16 | Seiko Epson Corp | Acceleration sensor |
| EP3021125A1 (en) * | 2014-11-14 | 2016-05-18 | Honeywell International Inc. | In-plane vibrating beam accelerometer |
| CN107015025A (en) * | 2017-05-12 | 2017-08-04 | 北京航空航天大学 | A kind of differential type graphene resonance beam acceleration transducer |
| CN109239399A (en) * | 2018-08-27 | 2019-01-18 | 中国计量大学 | Resonance type accelerometer based on bifilar forked type resonance beam |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1912075A1 (en) * | 2006-10-12 | 2008-04-16 | CSEM Centre Suisse d'Electronique et de Microtechnique SA Recherche et Développement | Accelerometer using resonant tuning-fork with balancing masses |
| CN101551404B (en) * | 2009-05-11 | 2011-01-26 | 清华大学 | An acceleration transducer based on nano-resonator and method of producing the same |
| US9759739B2 (en) * | 2011-02-02 | 2017-09-12 | Honeywell International Inc. | MEMS vibrating-beam accelerometer with piezoelectric drive |
| CN102608355B (en) * | 2011-11-23 | 2017-03-15 | 中国计量学院 | Resonance dynamic balance tunnel current formula 3-axis acceleration sensor and manufacture method |
| CN102608356B (en) * | 2011-12-06 | 2018-09-21 | 中国计量学院 | A kind of double-shaft micromechanical resonant accelerometer structure and production method |
| CN102778583B (en) * | 2012-07-12 | 2014-07-23 | 西安交通大学 | Silicon substrate-based quartz resonance acceleration sensor chip with four-beam structure |
| CN109160484B (en) * | 2018-09-03 | 2020-04-21 | 合肥工业大学 | Piezoelectric type MEMS acceleration sensor and preparation method thereof |
-
2020
- 2020-07-20 CN CN202010699338.6A patent/CN111796119B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2011117944A (en) * | 2009-10-29 | 2011-06-16 | Seiko Epson Corp | Acceleration sensor |
| EP3021125A1 (en) * | 2014-11-14 | 2016-05-18 | Honeywell International Inc. | In-plane vibrating beam accelerometer |
| CN107015025A (en) * | 2017-05-12 | 2017-08-04 | 北京航空航天大学 | A kind of differential type graphene resonance beam acceleration transducer |
| CN109239399A (en) * | 2018-08-27 | 2019-01-18 | 中国计量大学 | Resonance type accelerometer based on bifilar forked type resonance beam |
Non-Patent Citations (1)
| Title |
|---|
| 左右分布式高灵敏硅微谐振加速度计结构设计;段晓敏 等;《半导体器件》;20180331;第43卷(第3期);第171-176页 * |
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