CN107907103B - A Surface Acoustic Wave Biaxial Inclination Sensing Structure - Google Patents

Abstract

A surface acoustic wave biaxial inclination sensing structure belongs to the technical field of microelectromechanical sensing. Multiple SAW resonator groups are fabricated on the back of the silicon single crystal substrate, input/output electrode pairs facing each SAW resonator are fabricated on the front side of the silicon single crystal substrate, and two pairs of input/output electrode pairs are fabricated above the array. The end-fixed suspension electrodes are in contact with one of the output electrodes in the corresponding input/output electrode pair array, or contact with the gap between the corresponding input/output electrode pairs, and are connected or disconnected according to the inclination angle of the substrate. The corresponding surface acoustic wave resonator and the output signal electrode output or do not output the resonance signal of the corresponding resonant frequency, and the biaxial inclination angle of the planar state and the horizontal state of the surface acoustic wave biaxial inclination angle sensing structure substrate can be obtained. .

Description

A Surface Acoustic Wave Biaxial Inclination Sensing Structure

technical field

The invention belongs to the technical field of microelectromechanical sensing, and relates to a sensor structure, in particular to a dual-axis tilt angle sensing structure and method based on a surface acoustic wave resonator.

Background technique

Inclination measurement is mainly to measure the inclination of the measured object relative to its horizontal position. The dual-axis inclination sensing device or instrument measures the inclination of the two axial directions of the plane where the sensed object is located relative to the horizontal plane. The monitoring and control of the attitude of the object to be measured, and the measurement of small inclination angles are widely used in many fields such as precision instrument leveling, aerospace and ship navigation attitude control, satellite communication and radar equipment orientation.

The inclination sensors in the current technology are based on the principle of Newton's law of gravity, such as patent 2008100377.X, with the help of electrolyte, when the inclination of the measured plane changes, the electrolyte maintains a horizontal state due to the action of gravity, so that the electrical parameters of the electrolyte are maintained. (resistance) changes, and the inclination of the measured object is detected accordingly. The disadvantage is that the measurement range is small, the sensitivity is low, and the sensor size is large.

Some are based on optical principles, such as patent 200780000628.X using a photodetector to receive and sense the reflected light incident from the light source to the measured object, and the output electrical signal of the photodetector changes with the angular deviation of the reflected light relative to the incident light. According to this, the change of the inclination angle of the object is detected, while the patent 201110188720.1 detects the magnitude and direction of the inclination angle of the measured object according to the corresponding relationship between the change of the center wavelength of the two fiber Bragg gratings and the inclination angle. The disadvantage is that the composition of the optical sensing system is relatively complex, and the measurement accuracy is difficult to meet the measurement requirements when the measurement range is large.

Micro-Electro-Mechanical Systems (MEMS) sensors have very high sensitivity to changes in physical quantities, and have also been used in the measurement of the inclination of objects. The inclination angle of the plane, patent 201610068956.4 Fix the dual-axis gravity acceleration sensor on the side of the inclined cylinder to be measured, and obtain the maximum inclination angle with the x-axis and y-axis by moving along the side of the inclined cylinder to be measured, and calculate the dual-axis gravity acceleration sensor. Measure the offset angle when the platform and the inclined cylinder fit, and find out the inclination angle between the inclined cylinder to be measured and the z-axis, while the patent CN 103528567 A combines the principle of gravity and uses two micro-pressure sensors arranged in symmetrical positions to balance the liquid. The state is detected to realize the detection of the inclination angle. The disadvantage is that most of the sensing output signals are analog, which is inconvenient to use the digital system for further signal acquisition and processing.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies in the prior art, the present invention provides a surface acoustic wave biaxial inclination sensing structure based on biaxial inclination sensing including a surface acoustic wave resonator and a MEMS double-ended fixed beam.

The invention includes a substrate, four surface acoustic wave resonator groups are arranged on the back of the substrate, four piezoelectric thin film regions respectively covered on the four surface acoustic wave resonator groups, and four input/output are arranged on the front side of the substrate Electrode group, four double-ended fixed suspension electrodes, four input signal electrodes, four output signal electrodes, several ground electrodes, four input/output metal through-hole groups and a number of grounding metal through holes are arranged on the substrate through hole;

The four surface acoustic wave resonator groups are respectively the first, second, third and fourth surface acoustic wave resonator groups, and the first and second surface acoustic wave resonator groups are relatively arranged on the substrate The third and fourth surface acoustic wave resonator groups are arranged opposite to the left and right parts of the substrate; the first and third surface acoustic wave resonator groups respectively include N horizontally arranged acoustic wave resonators. a surface wave resonator, the second and fourth surface acoustic wave resonator groups respectively include N-1 laterally parallel surface acoustic wave resonators; the N is an odd number;

The four input/output electrode groups are respectively the first, second, third and fourth input/output electrode groups, and the first, second, third and fourth input/output electrode groups are respectively arranged on the base. The front side of the sheet is arranged in a one-to-one correspondence with the first, second, third, and fourth surface acoustic wave resonator groups, and the first, second, third, and fourth input/output electrode groups respectively include corresponding The surface acoustic wave resonators in the surface acoustic wave resonator group have the same number of input/output electrode pairs, and each input/output electrode pair is respectively provided with an input electrode and an output electrode;

The four input signal electrodes are respectively the first, second, third and fourth input signal electrodes; the four output signal electrodes are respectively the first, second, third and fourth output signal electrodes; 2. The input electrodes of the third and fourth input/output electrode groups are respectively collected to the first, second, third and fourth input signal electrodes;

The four double-ended fixed suspension electrodes are respectively the first, second, third, and fourth double-ended fixed suspension electrodes, and the first, second, third, and fourth double-ended fixed suspension electrodes are two The terminals are respectively fixed on the substrate through fixed supports, the output electrodes of the input/output electrode pairs are respectively used as the bottom electrodes of the double-ended fixed suspension electrodes, and the first, second, third, and fourth double-ended electrodes are respectively used. One of the fixed supports at both ends of the fixed-support suspension electrode is respectively connected with the first, second, third and fourth output signal electrodes; each of the double-ended fixed-support suspension electrodes respectively straddles the upper part of each input/output electrode pair array , the double-ended fixed-support suspension electrode sags naturally, and the position of its sagging point depends on the inclination angle of the substrate;

The input/output metal through hole groups are respectively arranged on each of the input/output electrode groups, and each input/output metal through hole group includes the same number of input/output electrode pairs as the input/output electrode pairs in the corresponding input/output electrode group /Output metal through hole pair, the input/output metal through hole pair respectively includes an input metal hole and an output metal hole, one end of the input metal through hole is connected to the corresponding input electrode on the front side of the substrate, and the other end is connected to the corresponding input electrode on the back side of the substrate The input signal bus electrode of the surface acoustic wave resonator, one end of the output metal through hole is connected to the output electrode corresponding to the front of the substrate, and the other end is connected to the output signal bus electrode of the surface acoustic wave resonator corresponding to the back of the substrate;

The ground electrodes are divided into two places, the ground electrodes are respectively opposite to the short-circuit bus electrodes at both ends of the surface acoustic wave resonators on the back of the substrate, and one end of each of the ground metal through holes is connected to the ground electrode corresponding to the front of the substrate, and the other end is connected to the ground electrode. Connect the short-circuit bus electrodes of the corresponding surface acoustic wave resonators on the back of the substrate.

In the present invention, a plurality of surface acoustic wave resonator groups are fabricated on the back of the substrate to form two sets of surface acoustic wave resonator arrays respectively arranged along the longitudinal front-rear direction and the lateral left-right direction. The input/output electrode pairs of the wave resonator constitute two groups of input/output electrode arrays along the longitudinal front-rear direction and the lateral left-right direction respectively, and each input/output electrode pair on the front side of the substrate faces the corresponding acoustic surfaces on the back side of the substrate in turn. In the wave resonator, a double-ended fixed suspension electrode is made above the array of each input/output electrode pair. The double-ended fixed suspended electrode hangs down naturally. The position of the sagging point depends on the inclination angle of the substrate. One output electrode in the input/output electrode group is in contact with one output electrode, or in contact with one output electrode gap in the input/output electrode group it spans, connecting or not connecting the corresponding surface acoustic wave resonator with the output signal electrode, outputting or not. Output the resonant signal of the corresponding resonant frequency, according to the combined characteristics of the resonant frequency values of the resonant signals output by the four output signal electrodes, according to the resonant frequency value of the output resonant signal, the SAW resonator corresponding to the resonant frequency is The position in the resonator group is the relationship between the position of the output electrode contacted by the sag point of the corresponding double-ended fixed suspension electrode and the inclination angle of the surface acoustic wave biaxial inclination angle sensing structure substrate in two directions, The biaxial inclination angle of the plane and the horizontal plane where the surface acoustic wave biaxial inclination angle sensing structure substrate is located can be obtained.

The present invention can sense the biaxial inclination angle of the plane where the object to be sensed is located relative to the horizontal plane in real time and online, sense the quasi-digital frequency value, easy to digitize, and facilitate the use of digital systems to further collect, process and transmit the measurement results , and the surface acoustic wave biaxial inclination sensing structure based on silicon single crystal substrate is easy to realize on-chip integration with peripheral signal processing circuit, small size and light weight.

In the present invention, a gap is provided between each surface acoustic wave resonator, and the gap is the width of one surface acoustic wave resonator; the gap between each input/output electrode pair is the width of one input/output electrode pair, and the each The width of the input/output electrode pair is the same and consistent with the width of the surface acoustic wave resonator on the back of the substrate, which facilitates the alignment of each input metal through hole and the alignment of the corresponding input electrode and the input signal bus electrode and each output metal through hole. And connect the corresponding output electrode and the output signal bus electrode.

Each input/output electrode pair in the second input/output electrode group faces the gap of each input/output electrode pair in the first input/output electrode group in turn, and each input/output electrode pair in the fourth input/output electrode group The input/output electrode pairs are facing the gap of each input/output electrode pair in the third input/output electrode group in turn; then when the vertical point of the double-ended fixed suspension electrodes is caused by the tilt of the substrate, the corresponding input/output electrode group When moving up, if the vertical point of the first (or third) double-ended fixed suspension electrode falls on the gap of an input/output electrode pair, the corresponding second (or fourth) double-ended fixed suspended electrode will have a vertical point. The vertical point just falls on the output electrode of one input/output electrode pair directly opposite the gap, and vice versa, so that the vertical point of each double-ended fixed suspension electrode and each input/output electrode pair can be seamlessly connected contact to ensure the continuity of the entire sensing process.

The resonance frequency of each surface acoustic wave resonator of the present invention is from left to right according to the first surface acoustic wave resonator of the first surface acoustic wave resonator group and the first surface acoustic wave resonator of the second surface acoustic wave resonator group. SAW resonator, the second SAW resonator of the first SAW resonator group, the second SAW resonator of the second SAW resonator group... the first SAW resonator The N-1 th surface acoustic wave resonator of the surface acoustic wave resonator group, the N-1 th surface acoustic wave resonator of the second surface acoustic wave resonator group, the N-1 th surface acoustic wave resonator of the first surface acoustic wave resonator group The sequence of the N surface acoustic wave resonators increases or decreases sequentially;

The resonant frequency of each surface acoustic wave resonator is according to the first surface acoustic wave resonator of the third surface acoustic wave resonator group and the first surface acoustic wave resonator of the fourth surface acoustic wave resonator group from front to back. resonator, the second surface acoustic wave resonator of the third surface acoustic wave resonator group, the second surface acoustic wave resonator of the fourth surface acoustic wave resonator group...the third surface acoustic wave The N-1th surface acoustic wave resonator of the resonator group, the N-1th surface acoustic wave resonator of the fourth surface acoustic wave resonator group, the Nth acoustic wave resonator of the third surface acoustic wave resonator group The order of the surface wave resonators is sequentially increasing or decreasing.

The surface acoustic wave resonator of the present invention includes an interdigital transducer and two short-circuit reflection arrays respectively located on both sides of the interdigital transducer, and the interdigital transducer includes two groups of interdigital electrodes arranged in opposite directions. and the input signal bus electrodes and the output signal bus electrodes at both ends, the short-circuit reflection array includes a group of short-circuit finger electrodes and two short-circuit bus electrodes at both ends, the width of each surface acoustic wave resonator is the same, the surface acoustic wave The width of the resonator is the sum of the aperture of the interdigitated electrode of the surface acoustic wave resonator and the width of the input signal bus electrode and the output signal bus electrode at both ends, or the aperture of the short-circuit finger electrode of the surface acoustic wave resonator and its two short circuits at both ends. The sum of the widths of the bus electrodes. Since the apertures of the interdigitated electrodes or short-circuit finger electrodes of the SAW resonators with different resonant frequencies are different, the widths of the input signal bus electrodes and the output signal bus electrodes or the two short-circuit bus electrodes at both ends are correspondingly set to make The width of each surface acoustic wave resonator is the same.

The material of the substrate of the present invention is single crystal silicon or quartz, the material of the piezoelectric thin film region is zinc oxide or aluminum nitride, the interdigital electrodes of the interdigital transducer, the input signal bus electrodes, the output The inner wall of the signal bus electrode, the short-circuit electrode of the short-circuit reflection array, the short-circuit bus electrode, the input electrode, the output electrode, the input signal electrode, the output signal electrode, the ground electrode and the metal through hole is made of gold or copper or aluminum or aluminum-copper alloy. Thin-film structure, the double-end fixed-support suspension electrode is a soft gold thick-film structure, and its fixed-support base is a gold or copper thick-film structure.

Description of drawings

Fig. 1 is the backside structure schematic diagram of the substrate of the present invention;

Fig. 2 is the schematic diagram of the front structure of the substrate of the present invention;

3 is a schematic diagram of the partial structure of the double-ended fixed support suspension electrode area of the present invention;

Fig. 4 is the structure of the surface acoustic wave resonator on the back of the substrate of the present invention and the position between the input/output electrode pair, the input signal electrode, the ground electrode, the input/output metal through hole pair and the ground metal through hole on the front side of the substrate Relationship diagram.

Detailed ways

As shown in Figures 1, 2, 3, and 4, the SAW biaxial tilt sensing structure includes a substrate 1, and four SAW resonator groups 2-1 and 2-2 fabricated on the back of the substrate 1. , 2-3, 2-4 respectively cover the four piezoelectric film regions 3 on the four surface acoustic wave resonator groups, and make four input/output electrode groups 4-1, 4-2 on the front side of the substrate 1 , 4-3, 4-4, four double-ended fixed suspension electrodes 8-1, 8-2, 8-3, 8-4, four input signal electrodes 51, 52, 53, 54, four output signals Electrodes 61, 62, 63, 64, several ground electrodes 7, four input/output metal through hole groups and several ground metal through holes 10 are made on the substrate 1 and pass through the substrate 1;

Among the four surface acoustic wave resonator groups 2-1, 2-2, 2-3, and 2-4, the first surface acoustic wave resonator group 2-1 and the second surface acoustic wave resonator group 2-2 are at the base. The back of the sheet 1 is arranged back and forth, the first surface acoustic wave resonator group 2-1 on the front side includes N surface acoustic wave resonators 21 arranged in horizontal parallel, and the second surface acoustic wave resonator group 2-2 on the rear side includes N -1 SAW resonators 21 arranged laterally in parallel, the gap between each SAW resonator 21 is the width of one SAW resonator 21, and each SAW in the second SAW resonator group 2-2 The wave resonators 21 are in turn facing the gaps between the respective surface acoustic wave resonators 21 in the first surface acoustic wave resonator group 2-1, and the N is an odd number;

Among the four surface acoustic wave resonator groups 2-1, 2-2, 2-3, and 2-4, the third surface acoustic wave resonator group 2-3 and the fourth surface acoustic wave resonator group 2-4 are at the base. The back of the sheet 1 is arranged left and right, the third surface acoustic wave resonator group 2-3 on the left side includes N surface acoustic wave resonators 21 arranged in parallel in the longitudinal direction, and the fourth surface acoustic wave resonator group 2-4 on the right side includes N -1 longitudinally parallel surface acoustic wave resonators 21, the gap between each surface acoustic wave resonator 21 is one surface acoustic wave resonator 21 width, and each surface acoustic wave resonator in the fourth surface acoustic wave resonator group 2-4 The wave resonators 21 face the gaps between the respective surface acoustic wave resonators 21 in the third surface acoustic wave resonator group 2-3 in turn, and the N is an odd number;

The resonant frequencies of the respective SAW resonators in the first SAW resonator group 2-1 and the second SAW resonator group 2-2 are different from each other, and the resonant frequencies of the respective SAW resonators are from left to Right click on the first SAW resonator in the first SAW resonator group 2-1, the first SAW resonator in the second SAW resonator group 2-2, the first SAW resonator in the second SAW resonator group 2-2 The second surface acoustic wave resonator in the wave resonator group 2-1, ..., the N-1th surface acoustic wave resonator in the first surface acoustic wave resonator group 2-1, the second surface acoustic wave resonator The order of the N-1 th surface acoustic wave resonator in the group 2-2 and the N th surface acoustic wave resonator in the first surface acoustic wave resonator group 2-1 is sequentially increasing or decreasing, and the N is an odd number ;

The resonant frequencies of the respective SAW resonators in the third SAW resonator group 2-3 and the fourth SAW resonator group 2-4 are different from each other, and the resonant frequencies of the respective SAW resonators were previously After arriving, press the first surface acoustic wave resonator in the third surface acoustic wave resonator group 2-3, the first surface acoustic wave resonator in the fourth surface acoustic wave resonator group 2-4, the third acoustic wave resonator The second SAW resonator in the surface wave resonator group 2-3, ..., the N-1th SAW resonator in the third SAW resonator group 2-3, the fourth SAW resonator The order of the N-1 th surface acoustic wave resonator in the group 2-4 and the N th surface acoustic wave resonator in the third surface acoustic wave resonator group 2-3 is sequentially increasing or decreasing, and the N is odd number;

The surface acoustic wave resonator 21 includes an interdigital transducer 22 and two short-circuit reflection arrays 23 respectively located on both sides of the interdigital transducer. The input signal bus electrodes 222 and the output signal bus electrodes 223 at both ends, the short-circuit reflection array 23 includes a group of short-circuit finger electrodes 231 and two short-circuit bus electrodes 232 at both ends, the width of each surface acoustic wave resonator is the same, and the surface acoustic wave resonates The width of the resonator is the sum of the aperture of the interdigitated electrode 221 of the surface acoustic wave resonator and the width of the input signal bus electrode 222 and the output signal bus electrode 223 at both ends, or the aperture of the short-circuit finger electrode 231 of the surface acoustic wave resonator and its two ends. The sum of the widths of the two short-circuit bus electrodes 232, the apertures of the interdigitated electrodes 221 or the short-circuit finger electrodes 231 of the SAW resonators with different resonance frequencies are different, and the input signal bus electrodes 222 and the output signal bus electrodes at both ends thereof The widths of the electrodes 223 or the two short-circuit bus electrodes 232 are correspondingly set so that the widths of the respective surface acoustic wave resonators are the same;

Among the four input/output electrode groups 4-1, 4-2, 4-3, and 4-4, the first input/output electrode group 4-1 and the second input/output electrode group 4-2 are on the front side of the substrate 1 The first surface acoustic wave resonator group 2-1 and the second surface acoustic wave resonator group 2-2, the third input/output electrode group 4-3 and the fourth input/output electrode group 4-3 and the fourth input/output electrode group 2-1 and 10 The electrodes 4-4 are arranged on the left and right sides of the front surface of the substrate 1 and face the third surface acoustic wave resonator group 2-3 and the fourth surface acoustic wave resonator group 2-4 on the back surface of the substrate 1, and the respective input/output electrodes The group includes the same number of input/output electrode pairs 41 as the surface acoustic wave resonators 21 in the corresponding surface acoustic wave resonator group, and each input/output electrode pair 41 faces the corresponding respective surface acoustic wave resonators 21 in turn, The gap between each input/output electrode pair 41 is the width of one input/output electrode pair 41, and the width of each input/output electrode pair 41 is the same and consistent with the width of the surface acoustic wave resonator 21 on the back of the substrate 1 , each input/output electrode pair 41 in the second input/output electrode group 4-2 faces the gap of each input/output electrode pair 41 in the first input/output electrode group 4-1 in turn, and the first input/output electrode pair 41 in the first input/output electrode group 4-1. Each input/output electrode pair 41 in the four input/output electrode groups 4-4 is in turn facing the gap of each input/output electrode pair 41 in the third input/output electrode group 4-3;

The input/output electrode pair 41 includes an input electrode 411 and an output electrode 412, each input electrode 411 is respectively facing the input signal bus electrode 222 of each surface acoustic wave resonator corresponding to the back of the substrate 1, and each output electrode 412 is facing respectively. The output signal bus electrode 223 of each surface acoustic wave resonator 21 corresponding to the back of the substrate 1, the first input/output electrode group 4-1, the second input/output electrode group 4-2, and the third input/output electrode group 4 -3 and the respective input electrodes 411 in the fourth input/output electrode group 4-4 are collected to the first input signal electrode 51, the second input signal electrode 52, the third input signal electrode 53 and the fourth input signal electrode 54, respectively, Each output electrode 412 in each input/output electrode group 4-1, 4-2, 4-3, 4-4 is simultaneously used as the bottom electrode of the corresponding double-ended fixed suspension electrode;

Each double-ended fixed suspension electrode 8-1, 8-2, 8-3, 8-4 is respectively fixed on the fixed support base 81 at both ends, wherein the first double-ended fixed suspension electrode 8-1, the second The double-end clamped suspension electrode 8-2, the third double-end clamped suspension electrode 8-3, and the fourth double-end clamped suspension electrode 8-4 straddle the first input/output electrode group 4- as the bottom electrode thereof, respectively 1. Each output electrode 412 in the second input/output electrode group 4-2, the third input/output electrode group 4-3 and the fourth input/output electrode group 4-4, the first double-ended fixed suspension electrode 8 -1. One of the two fixed bases 81 of the second double-ended fixed suspension electrode 8-2, the third double-ended fixed suspended electrode 8-3 and the fourth double-ended fixed suspended electrode 8-4, respectively connected to the first output signal electrode 61, the second output signal electrode 62, the third output signal electrode 63 and the fourth output signal electrode 64;

Each input/output metal through hole group 9 is respectively fabricated on the corresponding input/output electrode group, and each input/output metal through hole group 9 includes the same number of input/output electrode pairs as the input/output electrode pair in the corresponding input/output electrode group. /output metal through hole pair 91, the input/output metal through hole pair 91 includes an input metal through hole 911 and an output metal through hole 912, one end of the input metal through hole 911 is connected to the input electrode 411 corresponding to the front surface of the substrate 1 , the other end is connected to the input signal bus electrode 222 of the interdigital transducer 22 of the surface acoustic wave resonator 21 corresponding to the back of the substrate 1, one end of the output metal through hole 912 is connected to the output electrode 412 corresponding to the front of the substrate 1, and the other end connecting the output signal bus electrode 223 of the interdigital transducer 22 of the surface acoustic wave resonator 21 corresponding to the back of the substrate 1;

The ground electrode 7 faces the short-circuit bus electrodes 232 of the short-circuit reflection arrays 23 of each surface acoustic wave resonator on the back of the substrate 1, and each ground metal through hole 10 has one end connected to the ground electrode 7 corresponding to the front of the substrate 1, and the other end connected to the ground electrode 7. The surface acoustic wave resonator corresponding to the back of the sheet 1 short-circuits the short-circuit bus electrodes 232 of the reflection array 23 .

The above-mentioned surface acoustic wave resonator is a single-ended pair resonance structure, or a double-ended pair resonance structure;

The material of the substrate is single crystal silicon or quartz, the material of the piezoelectric thin film region 3 is zinc oxide or aluminum nitride, the interdigital electrodes 221 of the interdigital transducer 22, the input signal bus electrodes 222, The output signal bus electrode 223, the short circuit electrode 231 of the short circuit reflector 23, the short circuit bus electrode 232, the input electrode 411, the output electrode 412, the input signal electrode 51, the output signal electrode 62, the ground electrode 7 and the inner wall of the metal through hole are made of gold or Copper or aluminum or aluminum-copper alloy thin film structure, the double-ended fixed-support suspension electrode is a soft gold thick-film structure, and its fixed-support base is a gold or copper thick-film structure.

The working principle of the SAW dual-axis tilt sensing structure is as follows:

The substrate 1 and the surface acoustic wave biaxial inclination angle sensing structure fabricated on it constitute a surface acoustic wave biaxial inclination angle sensing chip;

The first input signal electrode 51, the second input signal electrode 52, the third input signal electrode 53 and the fourth input signal electrode 54 on the chip and the corresponding ground electrode 7 respectively form four input ports. The first output signal on the chip The electrode 61, the second output signal electrode 62, the third output signal electrode 63 and the fourth output signal electrode 64 and the corresponding ground electrode 7 respectively form four output ports, and each group of input ports and output ports are connected to a network analyzer or frequency meter. , used to detect the resonance signal and its frequency output by each SAW resonator;

If the surface of the surface acoustic wave biaxial inclination sensing chip is in a horizontal state, each double-ended fixed suspension electrode sags naturally, and its drooping point is the midpoint of the suspension electrode, and the first double-ended fixed suspension electrode 8-1 and the third The drooping point of the double-ended fixed suspension electrode 8-3 is just in contact with the central output electrode 412 of the first input/output electrode group 4-1 and the third input/output electrode group 4-3 below it as its bottom electrode, respectively , make the corresponding surface acoustic wave resonator 21 communicate with the output signal electrodes 61 and 63, output the resonance signal of the corresponding resonance frequency value, and the second double-ended fixed suspension electrode 8-2 and the fourth double-ended fixed suspension electrode 8 The drooping point of -4 is just in contact with the middle output electrode gap in the second input/output electrode group 4-2 and the fourth input/output electrode group 4-4 below it, respectively, and does not communicate with the corresponding surface acoustic wave resonator 21 With the output signal electrodes 62 and 64, no resonance signal is output;

If the plane where the surface acoustic wave dual-axis tilt angle sensing chip is located is inclined to the left or to the right, the sagging points of the first double-ended fixed suspension electrode 8-1 and the second double-ended fixed suspension electrode 8-2 move to the left or Move to the right, corresponding to the angle of inclination of the substrate: or the sagging point of the first double-ended suspension electrode 8-1 is just left with the middle of the first input/output electrode group 4-1 below it as its bottom electrode, or One of the output electrodes 412 to the right of the middle is in contact, so that the corresponding surface acoustic wave resonator 21 is communicated with the output signal electrode 61, and the resonance signal of the corresponding resonance frequency value is output, while the second double-ended fixed suspension electrode 8-2 sags. The point is just in contact with an output electrode gap in the second input/output electrode group 4-2 below the output electrode 412, and the corresponding surface acoustic wave resonator 21 and the output signal electrode 62 are not connected, and no resonance signal is output. , or the sagging point of the second double-ended fixed suspension electrode 8-2 is just in contact with an output electrode 412 in the left or right center of the second input/output electrode group 4-2 below it as its bottom electrode , the corresponding surface acoustic wave resonator 21 is communicated with the output signal electrode 62, and the resonance signal of the corresponding resonance frequency value is output, and the sagging point of the first double-ended fixed suspension electrode 8-1 is just opposite to the above-mentioned output electrode 412 below it. One of the output electrodes in the first input/output electrode group 4-1 is in contact with the gap, and the corresponding surface acoustic wave resonator 21 and the output signal electrode 61 are not connected, and no resonance signal is output. At the same time, the third double-ended fixed suspension electrode The sagging point of 8-3 is kept in contact with the output electrode 412 centered in the third input/output electrode group 4-3 below it as its bottom electrode, so that the corresponding surface acoustic wave resonator 21 is communicated with the output signal electrode 63, and the output The resonance signal of the corresponding resonance frequency value, the sagging point of the fourth double-ended fixed suspension electrode 8-4 is kept in contact with the middle output electrode gap in the fourth input/output electrode group 4-4 below it, and the corresponding sound is not connected. The surface wave resonator 21 and the output signal electrode 64 have no resonance signal output;

If the plane of the surface acoustic wave biaxial inclination sensing chip is inclined forward or backward, the sagging points of the third double-ended fixed suspension electrode 8-3 and the fourth double-ended fixed suspension electrode 8-4 move forward or backward move, corresponding to the angle of inclination of the substrate: or the sagging point of the third double-ended suspension electrode 8-3 is exactly the same as the bottom electrode of each output electrode 412 in the third input/output electrode group 4-3 below it. One of the output electrodes 412 at the front or the rear of the center is in contact, so that the corresponding surface acoustic wave resonator 21 is communicated with the output signal electrode 63, and the resonance signal of the corresponding resonance frequency value is output, and the fourth double-ended fixed suspension electrode 8 The drooping point of -4 is just in contact with an output electrode gap in the fourth input/output electrode group 4-4 below the output electrode facing the above-mentioned output electrode, and the corresponding surface acoustic wave resonator 21 and the output signal electrode 64 are not connected. Resonance signal output, or the sagging point of the fourth double-ended fixed suspension electrode 8-4 is just in front of or in the middle of each output electrode 412 in the fourth input/output electrode group 4-4 whose bottom electrode is below it. The last output electrode 412 is in contact, so that the corresponding surface acoustic wave resonator 21 is communicated with the output signal electrode 64, and the resonance signal of the corresponding resonance frequency value is output, and the sagging point of the third double-ended fixed suspension electrode 8-3 is just right. It is in contact with an output electrode gap in the third input/output electrode group 4-3 facing the above-mentioned output electrode 412 below it, and the corresponding surface acoustic wave resonator 21 and the output signal electrode 63 are not connected, no resonance signal is output, and at the same time The sagging point of the first double-ended suspension electrode 8-1 is kept in contact with the output electrode 412 in the center of the first input/output electrode group 4-1 below it as its bottom electrode, so that the corresponding surface acoustic wave resonator 21 Be communicated with the output signal electrode 61, output the resonance signal of the corresponding resonance frequency value, the sagging point of the second double-ended fixed suspension electrode 8-2 keeps the output electrode gap centered in the second input/output electrode group 4-2 below it In contact, the corresponding surface acoustic wave resonator 21 and the output signal electrode 62 are not connected, and no resonance signal is output;

That is, when the plane where the surface acoustic wave dual-axis tilt angle sensing chip is located is in a horizontal state, the first output signal electrode 61 and the third output signal electrode 63 respectively output exactly the surface acoustic wave resonance in the center of the corresponding surface acoustic wave resonator group. The resonant signal of the resonant frequency value of the device 21, while the second output signal electrode 62 and the fourth output signal electrode 64 do not output the resonant signal;

That is, when the plane where the surface acoustic wave dual-axis tilt angle sensing chip is located is inclined left or right, one of the outputs of the first output signal electrode 61 and the second output signal electrode 62 is inclined to the left or right in the corresponding surface acoustic wave resonator group. The resonant signal of the resonant frequency value of the surface acoustic wave resonator 21, the other does not output the resonance signal, and the third output signal electrode 63 outputs exactly the corresponding surface acoustic wave resonator 21 in the center of the surface acoustic wave resonator group. The resonance signal of the resonance frequency value, the fourth output signal electrode 64 does not output the resonance signal;

That is, when the plane where the surface acoustic wave dual-axis tilt angle sensing chip is located is tilted forward or backward, one of the outputs of the third output signal electrode 63 and the fourth output signal electrode 64 is tilted forward or backward in the corresponding surface acoustic wave resonator group. The resonant signal of the resonant frequency value of the deviated SAW resonator 21, the other does not output the resonant signal, and the first output signal electrode 61 outputs exactly the SAW resonator in the center of the corresponding SAW resonator group The resonant signal of the resonant frequency value of 21, the second output signal electrode 62 does not output the resonant signal;

Accordingly, the resonant frequency values of the resonant signals output by the four output signal electrodes are simultaneously measured, the combined characteristics of the resonant frequency values of the four output resonant signals are analyzed, and according to the resonant frequency values of the above-mentioned output resonant signals, the corresponding resonant frequency The position of the surface acoustic wave resonator in the surface acoustic wave resonator group to which it belongs, that is, the position of the output electrode contacted by the sag point of the corresponding double-ended fixed suspension electrode and the surface acoustic wave biaxial inclination angle sensing structure substrate are mutually in each other. The relationship between the inclination angles in the two vertical axial directions can obtain the biaxial inclination angle of the plane where the surface acoustic wave biaxial inclination angle sensing structure substrate is located relative to the horizontal plane.

In application, a high-frequency oscillation circuit can also be formed by connecting an external feedback amplifier circuit and a phase-shifting network through the input port composed of the input signal electrode and the corresponding ground electrode and the output port composed of the input signal electrode and the corresponding ground electrode. The high-frequency oscillation signal whose frequency is consistent with the resonant frequency of the corresponding surface acoustic wave resonator, use a network analyzer or frequency meter to detect the high-frequency oscillation signal and its frequency, instead of directly detecting the output resonant signal and its frequency, to improve the detection sensitivity and operability.

The typical implementation steps of the surface acoustic wave dual-axis tilt sensing structure are as follows:

(1) The silicon single crystal substrate is spin-coated with positive photoresist, exposed and developed to remove the photoresist film where the through-silicon hole to be formed is located;

(2) Etching to form through-silicon vias;

(3) Magnetron sputtering, the inner wall of TSV is covered with aluminum-copper alloy film;

(4) Remove glue;

(5) Double-sided polishing of silicon single crystal substrate;

(6) Spin-coat positive photoresist on the bottom surface of silicon single crystal substrate, expose and develop, remove 4 surface acoustic wave resonances including interdigitated electrodes, input signal bus electrodes, output signal bus electrodes, short-circuit finger electrodes, and short-circuit bus electrodes The photoresist film where the metal structure of the device group is located;

(7) Magnetron sputtering covers the aluminum-copper alloy film;

(8) Degumming, together with removing the aluminum-copper alloy film covering it, to obtain 4 surface acoustic wave resonator group metals including interdigital electrodes, input signal bus electrodes, output signal bus electrodes, short-circuit finger electrodes, and short-circuit bus electrodes. structure;

(9) Cleaning the silicon single crystal substrate;

(10) Magnetron sputtering, the metal structure of the four surface acoustic wave resonator groups on the bottom of the substrate is covered with a zinc oxide film;

(11) Spin-coat positive photoresist on the zinc oxide film, and remove the photoresist film in the non-piezoelectric film area by photolithography;

(12) Wet etching to remove the zinc oxide film in the non-piezoelectric film region;

(13) Degumming;

(14) The positive photoresist is spin-coated on the front of the substrate, exposed and developed to remove the photoresist where the 4 groups of input/output electrode groups, 4 input signal electrodes, 4 output signal electrodes and the ground electrode are to be prepared. membrane;

(15) Magnetron sputtering covers the aluminum-copper alloy film;

(16) Degumming, together with removing the aluminum-copper alloy film covering it, to obtain 4 groups of input/output electrode groups, 4 input signal electrodes, 4 output signal electrodes and ground electrodes;

(17) Spin-coating positive photoresist on the surface of the above-mentioned structural layer, exposing and developing to remove the photoresist film where the fixed electrodes at both ends of the four double-ended fixed suspension electrodes are located;

(18) Magnetron sputtering to cover the gold film;

(19) Degumming, together with removing the gold film covering it, to obtain the seed layers of the fixed electrodes at both ends of the four double-ended fixed suspension electrodes;

(20) spin-coating positive photoresist on the surface of the above-mentioned structural layer, and photolithography removes the photoresist film above the seed layer of the fixed electrodes at both ends of the four double-ended fixed suspension electrodes;

(21) Electroplating thick gold film;

(22) Remove the glue to obtain four fixed electrodes at both ends of the double-ended fixed-support suspension electrodes;

(23) Spin-coating positive photoresist on the surface of the above-mentioned structural layer, and photolithography removes the photoresist film where the sacrificial layer is located under the four double-ended fixed suspension electrodes to be fabricated;

(24) Magnetron sputtering to cover silicon dioxide thick film;

(25) Degumming, together with removing the silicon dioxide film covering it, to obtain four silicon dioxide sacrificial layers under the double-ended fixed suspension electrodes;

(26) Spin-coating positive photoresist on the surface of the above-mentioned structural layer, and photolithography removes two fixed electrodes of the four double-ended fixed suspension electrodes and the photoresist film above the silicon dioxide sacrificial layer;

(27) Magnetron sputtering to cover the gold film;

(28) Degumming, together with removing the gold film covering it, to obtain 4 seed layers of double-ended fixed suspension electrodes;

(29) Spin-coating positive photoresist on the surface of the above-mentioned structural layer, and photolithography removes the photoresist film above the seed layers of the four double-ended fixed suspension electrodes;

(30) Electroplating soft thick gold film;

(31) Degumming;

(32) Remove the silicon dioxide sacrificial layer under the 4 double-ended fixed suspension electrodes, and release the 4 double-ended fixed suspension electrodes, thereby completing the fabrication of the surface acoustic wave biaxial inclination angle sensing structure, and obtaining the surface acoustic wave biaxial Inclination sensor chip.

A specific implementation step of using the above-mentioned surface acoustic wave dual-axis inclination sensing chip to realize dual-axis inclination sensing is as follows:

(1) Calibrate chip level status

Measure the resonant frequency of the resonant signal output by the first, second, third, and fourth output signal electrodes respectively, and adjust the chip to be forward or backward, or left or right according to the measured value, so that the first output signal The resonant frequency of the resonant signal output by the electrode and the third output signal electrode is exactly the resonant frequency of the center surface acoustic wave resonator of the first surface acoustic wave resonator group and the third surface acoustic wave resonator group, respectively, and the second output The signal electrode and the fourth output signal electrode have no resonant signal output, and at this time, the plane where the chip is located is in a horizontal state;

(2) Calibrate the relationship between the chip inclination and the resonant frequency of the output resonant signal

① Make the chip tilt to the left from the horizontal state (0°), record the resonance frequency value and the corresponding tilt angle value of the resonance signal output by the first output signal electrode or the second output signal electrode, until the maximum (or minimum) resonance frequency is output. until the resonance signal of the value;

② Make the chip tilt to the right from the horizontal state (0°), record the resonance frequency value of the resonance signal output by the first output signal electrode or the second output signal electrode and the corresponding tilt angle value, until the output minimum (or maximum) resonance frequency until the resonance signal of the value;

③ Make the chip tilt forward from the horizontal state (0°), record the resonance frequency value and the corresponding tilt angle value of the resonance signal output by the third output signal electrode or the fourth output signal electrode, until the maximum (or minimum) resonance frequency is output. until the resonance signal of the value;

④ Make the chip tilt backward from the horizontal state (0°), record the resonance frequency value and the corresponding tilt angle value of the resonance signal output by the third output signal electrode or the fourth output signal electrode, until the minimum (or maximum) resonance frequency is output. until the resonance signal of the value;

⑤ Make the inclination angle calibration table with the inclination angle values of several groups of two mutually perpendicular axes measured above and the corresponding resonance frequency value of the output resonance signal;

⑥ Or fit the above-mentioned several groups of measured values to obtain the inclination calibration function or the inclination calibration curve.

(3) Measure the biaxial inclination of the chip

For any state of the chip, measure the resonant frequencies of the resonant signals output by the first, second, third, and fourth output signal electrodes respectively, and refer to the chip inclination calibration table or calibration function or calibration curve to determine where the chip is located. The biaxial inclination of the plane relative to the horizontal plane, namely:

According to the resonant frequency value of the resonant signal output by the first output signal electrode or the second output signal electrode, the inclination angle value of the forward or backward tilt of the plane where the chip is located is determined. At this time, the resonant frequency value of the resonant signal output by the third output signal electrode is exactly is the resonance frequency of the central surface acoustic wave resonator of the third surface acoustic wave resonator group, and the fourth output signal electrode has no resonance signal output;

Or according to the resonant frequency value of the resonant signal output by the third output signal electrode or the fourth output signal electrode, the inclination angle value of the left or right inclination of the plane where the chip is located is determined. At this time, the resonant frequency value of the resonant signal output by the first output signal electrode is exactly the resonance frequency of the central surface acoustic wave resonator of the first surface acoustic wave resonator group, and the second output signal electrode has no resonance signal output;

Or according to the resonance frequency of the resonance signal output by the first output signal electrode or the second output signal electrode and the third output signal electrode or the fourth output signal electrode, simultaneously determine the biaxial tilt angle of the plane where the chip is located.

It will be understood by those skilled in the art that although specific embodiments have been described herein for ease of explanation, various changes may be made without departing from the spirit and scope of the invention. Therefore, the invention is not to be limited except by the appended claims.

Claims (5)

1. A surface acoustic wave double-shaft inclination angle sensing structure is characterized by comprising a substrate, wherein four surface acoustic wave resonator groups and four piezoelectric film areas respectively covering the four surface acoustic wave resonator groups are arranged on the back surface of the substrate, four input/output electrode groups, four double-end fixedly-supported suspension electrodes, four input signal electrodes, four output signal electrodes and a plurality of grounding electrodes are arranged on the front surface of the substrate, and four input/output metal through hole groups and a plurality of grounding metal through holes penetrating through the substrate are arranged on the substrate;

the four surface acoustic wave resonator groups are respectively a first surface acoustic wave resonator group, a second surface acoustic wave resonator group, a third surface acoustic wave resonator group and a fourth surface acoustic wave resonator group, the first surface acoustic wave resonator group and the second surface acoustic wave resonator group are oppositely arranged at the front part and the rear part of the substrate, and the third surface acoustic wave resonator group and the fourth surface acoustic wave resonator group are oppositely arranged at the left part and the right part of the substrate; the first and third surface acoustic wave resonator groups respectively comprise N surface acoustic wave resonators arranged transversely in parallel, and the second and fourth surface acoustic wave resonator groups respectively comprise N-1 surface acoustic wave resonators arranged transversely in parallel; n is an odd number;

the resonant frequency of each surface acoustic wave resonator is sequentially increased or decreased from left to right according to the sequence of a first surface acoustic wave resonator of the first surface acoustic wave resonator group, a first surface acoustic wave resonator of the second surface acoustic wave resonator group, a second surface acoustic wave resonator of the first surface acoustic wave resonator group, a second surface acoustic wave resonator of the second surface acoustic wave resonator group, a second surface acoustic wave resonator … of the second surface acoustic wave resonator group and an N-1 surface acoustic wave resonator of the first surface acoustic wave resonator group;

the resonant frequency of each surface acoustic wave resonator is sequentially increased or decreased from front to back according to the sequence of a first surface acoustic wave resonator of the third surface acoustic wave resonator group, a first surface acoustic wave resonator of the fourth surface acoustic wave resonator group, a second surface acoustic wave resonator of the third surface acoustic wave resonator group, a second surface acoustic wave resonator … of the fourth surface acoustic wave resonator group, an N-1 surface acoustic wave resonator of the third surface acoustic wave resonator group, an N-1 surface acoustic wave resonator of the fourth surface acoustic wave resonator group and an N surface acoustic wave resonator of the third surface acoustic wave resonator group;

the four input/output electrode groups are respectively a first input/output electrode group, a second input/output electrode group, a third input/output electrode group and a fourth input/output electrode group, the first input/output electrode group, the second input/output electrode group, the third input/output electrode group and the fourth input/output electrode group are respectively arranged on the front surface of the substrate and are in one-to-one correspondence with the first surface acoustic wave resonator group, the second surface acoustic wave resonator group, the third surface acoustic wave resonator group and the fourth surface acoustic wave resonator group, the first input/output electrode group, the second input/output electrode group, the third input/output electrode group and the fourth input/output electrode group respectively comprise input/output electrode pairs with the same;

the four input signal electrodes are respectively a first input signal electrode, a second input signal electrode, a third input signal electrode and a fourth input signal electrode; the four output signal electrodes are respectively a first output signal electrode, a second output signal electrode, a third output signal electrode and a fourth output signal electrode; the input electrodes of the first, second, third and fourth input/output electrode groups are respectively collected to the first, second, third and fourth input signal electrodes;

the four double-end fixedly-supported suspension electrodes are respectively a first double-end fixedly-supported suspension electrode, a second double-end fixedly-supported suspension electrode, a third double-end fixedly-supported suspension electrode and a fourth double-end fixedly-supported suspension electrode, two ends of the first double-end fixedly-supported suspension electrode, two ends of the second double-end fixedly-supported suspension electrode, two ends of the third double-end fixedly-supported suspension electrode and two ends of the fourth double-end fixedly-supported suspension electrode are respectively fixed on the substrate through fixed supports, output electrodes of all input/output electrode pairs are respectively used as bottom electrodes of all double-end fixedly-supported suspension electrodes, and one of the fixed supports at two ends of the first double-end fixedly-supported; each double-end fixed support suspension electrode respectively spans above each input/output electrode pair array, the double-end fixed support suspension electrode naturally sags, and the position of a sagging point of the double-end fixed support suspension electrode is determined according to the inclination angle of the substrate;

the input/output metal through hole groups are respectively arranged on the input/output electrode groups, each input/output metal through hole group comprises input/output metal through hole pairs with the same number as the input/output electrode pairs in the corresponding input/output electrode group, each input/output metal through hole pair respectively comprises an input metal hole and an output metal hole, one end of each input metal through hole is connected with the input electrode corresponding to the front surface of the substrate, the other end of each input metal through hole is connected with the input signal bus electrode of the surface acoustic wave resonator corresponding to the back surface of the substrate, one end of each output metal through hole is connected with the output electrode corresponding to the front surface of the substrate, and the other end of each output metal through hole is connected with the output signal bus electrode of the surface acoustic wave resonator corresponding;

the grounding electrode is divided into two parts, the grounding electrode is respectively opposite to the short circuit bus electrodes at two ends of each surface acoustic wave resonator on the back surface of the substrate, one end of each grounding metal through hole is connected with the grounding electrode corresponding to the front surface of the substrate, and the other end of each grounding metal through hole is connected with the short circuit bus electrode of the surface acoustic wave resonator corresponding to the back surface of the substrate.

2. A surface acoustic wave biaxial inclination angle sensing structure as defined in claim 1, wherein gaps are provided between surface acoustic wave resonators, the gaps being the width of one surface acoustic wave resonator; the gap between each input/output electrode pair is the width of one input/output electrode pair, and the widths of the input/output electrode pairs are the same and are consistent with the width of the surface acoustic wave resonator on the back surface of the substrate.

3. A surface acoustic wave dual-axis tilt sensing structure according to claim 1, wherein each input/output electrode pair in said second input/output electrode group is sequentially opposed to the gap of each input/output electrode pair in said first input/output electrode group, and each input/output electrode pair in said fourth input/output electrode group is sequentially opposed to the gap of each input/output electrode pair in said third input/output electrode group.

4. The surface acoustic wave dual-axis tilt angle sensing structure according to claim 1, wherein the surface acoustic wave resonator comprises an interdigital transducer and two short-circuit reflection arrays respectively located at two sides of the interdigital transducer, the interdigital transducer comprises two sets of interdigital electrodes staggered in opposite directions and input signal bus electrodes and output signal bus electrodes at two ends thereof, the short-circuit reflection array comprises a set of short-circuit interdigital electrodes and two short-circuit bus electrodes at two ends thereof, each surface acoustic wave resonator has the same width, the width of the surface acoustic wave resonator is the sum of the aperture of the interdigital electrode of the surface acoustic wave resonator and the widths of the input signal bus electrodes and the output signal bus electrodes at two ends thereof or the sum of the aperture of the short-circuit interdigital electrode of the surface acoustic wave resonator and the widths of the two short-circuit bus electrodes at two ends thereof, the aperture of the interdigital electrodes or the short-circuit finger electrodes of each surface acoustic wave resonator is different from each other, the widths of the input signal bus electrode and the output signal bus electrode or the two short-circuit bus electrodes at the two ends of the short-circuit bus electrode are correspondingly set to make the widths of the surface acoustic wave resonators the same.

5. The structure of claim 4, wherein the piezoelectric thin film region is made of zinc oxide or aluminum nitride, the interdigital electrodes, the input signal bus electrodes, the output signal bus electrodes, the short-circuit electrodes of the short-circuit reflection array, the short-circuit bus electrodes, the input electrodes, the output electrodes, the input signal electrodes, the output signal electrodes, the ground electrodes, and the inner walls of the metal through holes of the interdigital transducers are made of gold or copper or aluminum-copper alloy thin film structures, the double-end fixed suspension electrode is made of a soft gold thick film structure, and the fixed base thereof is made of gold or copper thick film structure.

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