CN115598647A - Film piezoelectric sound pressure sensor and detection imaging device - Google Patents
Film piezoelectric sound pressure sensor and detection imaging device Download PDFInfo
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- CN115598647A CN115598647A CN202211592457.7A CN202211592457A CN115598647A CN 115598647 A CN115598647 A CN 115598647A CN 202211592457 A CN202211592457 A CN 202211592457A CN 115598647 A CN115598647 A CN 115598647A
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- 238000001514 detection method Methods 0.000 title claims abstract description 36
- 238000003384 imaging method Methods 0.000 title claims abstract description 30
- 239000010409 thin film Substances 0.000 claims abstract description 89
- 239000000758 substrate Substances 0.000 claims abstract description 38
- 239000010408 film Substances 0.000 claims abstract description 9
- 239000004065 semiconductor Substances 0.000 claims description 15
- 238000004806 packaging method and process Methods 0.000 claims description 13
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 12
- 229910052710 silicon Inorganic materials 0.000 claims description 12
- 239000010703 silicon Substances 0.000 claims description 12
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 7
- 229910052750 molybdenum Inorganic materials 0.000 claims description 7
- 239000011733 molybdenum Substances 0.000 claims description 7
- 238000005538 encapsulation Methods 0.000 claims description 6
- 239000000523 sample Substances 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 abstract description 21
- 238000010586 diagram Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 239000000463 material Substances 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000004088 simulation Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
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- 239000007772 electrode material Substances 0.000 description 1
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- 238000000206 photolithography Methods 0.000 description 1
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- 238000006467 substitution reaction Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
- G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
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- Piezo-Electric Transducers For Audible Bands (AREA)
Abstract
The invention discloses a film piezoelectric sound pressure sensor and a detection imaging device, wherein the film piezoelectric sound pressure sensor comprises a substrate and a plurality of sensing pixels positioned on one side of the substrate, the plurality of sensing pixels are arranged along a first direction, and the first direction is parallel to the plane of the substrate; the sensing pixel comprises a plurality of sensing units and an output electrode, wherein the sensing units are electrically connected with the output electrode; a plurality of sensitive units in the same sensing pixel are arranged along a second direction, and the second direction is parallel to the plane of the substrate and is intersected with the first direction; in the same sensing pixel, at least two sensitive units have different sizes. According to the invention, the plurality of sensing pixels are arranged in the thin film piezoelectric sound pressure sensor, and each sensing pixel is provided with at least two sensing units with different sizes, so that the bandwidth of the thin film piezoelectric sound pressure sensor working in a resonance state can be increased, and the working modes of high sensitivity and high bandwidth are ensured.
Description
Technical Field
The invention relates to the technical field of underwater detection imaging, in particular to a film piezoelectric sound pressure sensor and a detection imaging device.
Background
With the development of an image sonar system, the resolution ratio of the image sonar system is gradually improved, the functions of the image sonar system are gradually enriched, and the image sonar system is widely applied to occasions such as underwater detection, positioning navigation, underwater target identification and tracking, track measurement and the like.
The underwater imager is a device for underwater detection imaging manufactured based on the water acoustic principle. The acoustic wave transmitted by the underwater imager is transmitted in water, when the underwater imager meets a measured object, the acoustic wave is reflected, the hydrophone array of the underwater imager receives the acoustic wave reflected by the measured object, and the information such as the size, the shape, the distance and the like of the measured object is restored through an imaging algorithm according to the information such as acoustic pressure, phase and the like of the acoustic wave.
However, the existing underwater imager has the problems of poor performance of a sensing chip, narrow working bandwidth and insufficient sensitivity.
Disclosure of Invention
The invention provides a thin film piezoelectric sound pressure sensor and a detection imaging device, wherein a plurality of sensitive units with different sizes are arranged in a sensing pixel, so that the bandwidth of the thin film piezoelectric sound pressure sensor working in a resonance state is increased, and the working modes of high sensitivity and high bandwidth are ensured.
According to one aspect of the invention, a thin film piezoelectric sound pressure sensor is provided, wherein the thin film piezoelectric sound pressure sensor comprises a substrate and a plurality of sensing pixels arranged on one side of the substrate, the plurality of sensing pixels are arranged along a first direction, and the first direction is parallel to a plane where the substrate is located; the sensing pixel comprises a plurality of sensing units and an output electrode, wherein the sensing units are electrically connected with the output electrode; a plurality of sensitive units in the same sensing pixel are arranged along a second direction, and the second direction is parallel to the plane of the substrate and is intersected with the first direction; in the same sensing pixel, at least two sensitive units have different sizes.
Optionally, the number of the sensing units with different sizes in the same sensing pixel is the same.
Optionally, in the same sensing pixel, the sensing units with the same size are arranged in series or in parallel; the sensing units of different sizes are arranged in parallel.
Optionally, the sensing unit comprises a vacuum chamber arranged in the substrate, and a first electrode, a piezoelectric layer and a second electrode which are stacked and arranged on one side of the vacuum chamber away from the substrate; the output electrodes include a first output electrode electrically connected to the first output electrode and a second output electrode electrically connected to the second output electrode.
Optionally, the shape of at least the second electrode and the vacuum chamber comprises a circle.
Optionally, the second electrode and the vacuum chamber are of a concentric circle structure, and a radius R1 'of the second electrode and a radius R2' of the vacuum chamber satisfy R1'/R2' =0.7.
Optionally, the sensing unit further comprises a semiconductor silicon layer disposed between the vacuum chamber and the first electrode; the thickness d1 of the semiconductor silicon layer meets the condition that d1 is less than or equal to 4 mu m and less than or equal to 6 mu m; the first electrode comprises a molybdenum electrode, and the thickness d2 of the first electrode is less than or equal to 0.1 mu m and less than or equal to d2 and less than or equal to 0.2 mu m; the peak value a of the full width at half maximum curve of the piezoelectric layer satisfies a <0.3; the second electrode comprises a molybdenum electrode, and the thickness d3 of the second electrode is less than or equal to 0.1 mu m and less than or equal to d3 and less than or equal to 0.2 mu m.
Optionally, in any two sensing pixels, the setting modes of the sensing units are the same; the setting mode comprises the total number of the sensitive units, the number of the sensitive units with the same size and the arrangement mode of the sensitive units.
Optionally, along the first direction, a distance L1 between two adjacent sensing pixels and a center frequency f of the sensing pixel satisfy L1= f/4.
Optionally, the size of the thin film piezoelectric sound pressure sensor in the first direction is L2, and the size of the thin film piezoelectric sound pressure sensor in the second direction is L3; wherein, L2/L3 is more than or equal to 1 and less than or equal to 4.
Optionally, the thin film piezoelectric sound pressure sensor further includes a circuit board and a packaging layer; the circuit board is arranged on one side of the substrate far away from the sensing pixel, and the output electrode is electrically connected with the circuit board; the packaging layer is arranged on one side, far away from the substrate, of the sensing pixels, the packaging layer covers the sensing pixels, and the thickness d4 of the packaging layer is larger than or equal to 0.95mm and smaller than or equal to d4 and smaller than or equal to 1.05 mm.
According to another aspect of the present invention, there is provided a probe imaging apparatus, including a thin film piezoelectric acoustic pressure sensor; the thin film piezoelectric sound pressure sensor is arranged on the surface of the imaging instrument and is electrically connected with the imaging instrument; the transmitting transducer is used for emitting detection sound waves; the film piezoelectric sound pressure sensor is used for receiving a sound wave signal reflected by an object to be detected, converting the sound wave signal into a voltage signal and feeding back the voltage signal to the imager; the imager is used for determining the detection information of the object to be detected according to the voltage signal.
Optionally, the detection imaging device includes a plurality of thin film piezoelectric sound pressure sensors; a plurality of film piezoelectric sound pressure sensors are arranged on the surface of the imaging instrument in an array mode.
According to the invention, the plurality of sensing pixels are arranged in the thin film piezoelectric sound pressure sensor, the plurality of sensing units with different sizes are arranged in each sensing pixel, and the resonant frequency of each sensing unit is determined by the size of each sensing unit, so that the at least two sensing units with different sizes are arranged in each sensing pixel, and the multiple resonant frequency points are realized by the sensing units with different sizes, so that the bandwidth of the thin film piezoelectric sound pressure sensor working in a resonant state is increased, the working mode of high sensitivity and high bandwidth of the thin film piezoelectric sound pressure sensor is ensured, and the detection accuracy is ensured.
It should be understood that the statements in this section are not intended to identify key or critical features of the embodiments of the present invention, nor are they intended to limit the scope of the invention. Other features of the present invention will become apparent from the following description.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic diagram of a thin film piezoelectric acoustic pressure sensor according to an embodiment of the present invention;
FIG. 2 is a graph showing a simulation of the sensitivity of a thin film piezoelectric acoustic pressure sensor at a resonant frequency provided in the related art;
FIG. 3 is a graph illustrating a simulation of the sensitivity of a thin film piezoelectric acoustic pressure sensor at a resonant frequency according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a sensing unit provided in accordance with an embodiment of the present invention;
FIG. 5 is a schematic side view of a thin film piezoelectric acoustic pressure sensor according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a detection imaging apparatus according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a thin film piezoelectric acoustic pressure sensor array according to an embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions.
Fig. 1 is a schematic diagram of a thin film piezoelectric acoustic pressure sensor according to an embodiment of the present invention, and as shown in fig. 1, a thin film piezoelectric acoustic pressure sensor 100 according to an embodiment of the present invention includes a substrate 110 and a plurality of sensor pixels 120 located on one side of the substrate 110, where the plurality of sensor pixels 120 are arranged along a first direction, and the first direction is parallel to a plane where the substrate 110 is located; the sensor element 120 comprises a plurality of sensing units 121 and output electrodes 122, wherein the sensing units 121 are electrically connected with the output electrodes 122; a plurality of sensing units 121 in the same sensing pixel element 120 are arranged along a second direction, and the second direction is parallel to the plane of the substrate 110 and intersects with the first direction; in the same sensing pixel 120, at least two sensing units 121 have different sizes.
The substrate 110 may be a wafer made of a semiconductor material, for example, the substrate 110 may be a silicon substrate. The semiconductor substrate has higher stability, and the sensor element 120 is arranged on the basis of the semiconductor substrate, so that the reliability and the stability of the film piezoelectric sound pressure sensor are improved. The substrate 110 may also be made of other semiconductor materials, which is not limited in the embodiments of the invention.
The sensing pixel 120 may be a pixel for sensing pressure in the thin film piezoelectric sound pressure sensor 100, and one thin film piezoelectric sound pressure sensor 100 may have a plurality of sensing pixels 120, as shown in fig. 1, where the plurality of sensing pixels 120 are arranged along a first direction (e.g., an x direction shown in the figure), so that pressure sensing can be performed at different positions of the thin film piezoelectric sound pressure sensor 100. Specifically, in the thin film piezoelectric sound pressure sensor 100, the sensor element 120 first senses a pressure change to generate a voltage signal, and then outputs the voltage signal through the output electrode 122, so as to detect the pressure.
The sensing unit 121 can be a specific pressure sensing unit in the sensing pixel 120. One sensing pixel 120 can include a plurality of sensing units 121, as shown in fig. 1, the sensing units 121 in the same sensing pixel 120 are arranged along a second direction (e.g., the y direction shown in the figure), and pressure sensing at different positions is achieved through the plurality of sensing units 121 arranged in an array. Further, since the sensing unit 121 operates in the resonant state, the sensing unit 121 has the same parameters except for the size, so that the resonant frequency of the sensing unit 121 is determined by the size, and the sensing units 121 with different sizes determine different resonant frequencies. Fig. 2 is a graph showing a simulation of the sensitivity of a thin film piezoelectric sound pressure sensor at a resonant frequency provided in the related art, and as shown in fig. 2, when a sensing unit 121 with a single size is provided in the thin film piezoelectric sound pressure sensor 100, and the thin film piezoelectric sound pressure sensor 100 operates in a resonant state, the sensitivity is high but the bandwidth is small, and the requirements of precision and accuracy cannot be met in practical application. Further, fig. 3 is a sensitivity simulation graph of another thin film piezoelectric acoustic pressure sensor at a resonant frequency according to another embodiment of the present invention, and as shown in fig. 3, in order to increase a bandwidth of the thin film piezoelectric acoustic pressure sensor 100 at the resonant frequency, in an inventive embodiment of the present invention, at least two sensing units 121 with different sizes are disposed in a sensing pixel 120, where the sensing unit 121 with each size corresponds to a resonant frequency point, and multiple sensing units with different sizes implement that a single thin film piezoelectric acoustic pressure sensor 100 has a characteristic of multiple resonant frequency points, so that a high sensitivity is ensured and a high bandwidth working mode is implemented.
It should be noted that, in the embodiment of the present invention, the number of the sensing pixels included in the thin film piezoelectric sound pressure sensor is not limited, the number of the sensing units included in the same sensing pixel is not limited, the number of the sensing units with different sizes included in the same sensing pixel is also not limited, and the number of the sensing pixels and the number of the sensing units may be set according to the requirement of the detection bandwidth, the size of the sensing units, and the size of the thin film piezoelectric sound pressure sensor. It can be understood that, since the resonant frequency of the sensing units is determined by the sizes of the sensing units, the larger the number of the sensing units with different sizes is, the better the multi-resonant frequency point characteristics of the thin film piezoelectric sound pressure sensor are, and meanwhile, the more complicated the manufacturing process of the thin film piezoelectric sound pressure sensor is. Therefore, the detection bandwidth requirement and the process difficulty of the thin film piezoelectric sound pressure sensor can be integrated, and the number of the sensing units with different sizes in the thin film piezoelectric sound pressure sensor can be reasonably set. For example, the radius of the largest size sensitive unit 121 in the sensing pixel 120 is R1, the radius of the smallest size sensitive unit 121 is R4, and the operating frequency and the operating bandwidth of the sensing pixel 120 are jointly determined by R1 and R4.
In summary, in the thin film piezoelectric sound pressure sensor provided by the embodiment of the present invention, at least two sensing units with different sizes are arranged in a sensing pixel of the thin film piezoelectric sound pressure sensor, so that the sensitivity of the thin film piezoelectric sound pressure sensor to pressure change in a resonance state is improved by the sensing units with different sizes, a wider working bandwidth is obtained, and the detection accuracy is improved.
Optionally, with continued reference to fig. 1, the number of sensing elements 121 of different sizes is the same in the same sensing pixel 120.
Wherein, the same distribution number of the sensing units 121 with different sizes is required to be ensured in the same sensing pixel 120.
For example, the same number of sensing units 121 with different sizes in the same sensing pixel 120 is the same, and it can be understood that the same sensing pixel 120 includes the same number of sensing units 121 with different sizes, for example, for any size of sensing units, each sensing unit includes 2, or each sensing unit includes 3 or other numbers, so that it can be ensured that a single sensing pixel 120 has the same or similar sensitivities at different frequency points, that is, the consistency of in-band flatness and frequency response of the single sensing pixel 120 is ensured, and the sensing effect of the sensing pixel 120 is ensured to be good. Taking the thin-film piezoelectric acoustic pressure sensor shown in fig. 1 as an example, four different sizes of sensing units 121 are arranged in each sensing pixel element 120. The sensing units 121 with different sizes may be rectangular structures with different side lengths, circular structures with different radii, and the like, and the shape of the sensing unit 121 is not specifically limited herein. For example, taking the circle shown in fig. 1 as an example, the sensing elements 121 have the size radii of R1, R2, R3 and R4, and there are two sensing elements 121 in each size, so as to ensure good uniformity of in-band flatness and frequency response of a single sensing pixel element 120.
Optionally, as shown in fig. 1, in the same sensing pixel 120, the sensing units 121 with the same size are arranged in series or in parallel; the sensing units 121 of different sizes are arranged in parallel.
The sensing units 121 with the same size can be arranged in series or in parallel according to the detection requirement; the sensing units 121 with different sizes are arranged in parallel, so that the bandwidths corresponding to the sensing units 121 with different sizes are mutually superposed to obtain a larger bandwidth range. Taking the thin-film piezoelectric sound pressure sensor shown in fig. 1 as an example, the sensing unit 121 is circular, four sensing units 121 with different sizes are arranged in each sensing pixel element 120, and there are two sensing units 121 with different sizes. The sensing units 121 have radii of R1, R2, R3, and R4, where R1 is the largest sensing unit 121 and R4 is the smallest sensing unit 121. The sensing units 121 with the R1 size, the R2 size, the R3 size and the R4 size in the same sensing pixel 120 are respectively arranged in series or in parallel, that is, the sensing units 121 with the same size are connected in series or in parallel, the sensing units 121 with the R1 size, the R2 size, the R3 size and the R4 size are connected in parallel, and finally the upper and lower electrodes after being connected in parallel are connected with the output electrode 122. At this time, the operating frequency and the operating bandwidth of the sensing element 120 are determined by R1 and R4 together. Therefore, by limiting the connection mode of the sensitive units in the sensing pixel, the sensitive units with different sizes are connected in parallel to form the sensing pixel, and the working frequency and the working bandwidth of a single sensing pixel are increased.
Optionally, with reference to fig. 1, in any two sensor elements 120, the arrangement manner of the sensing units 121 is the same; the arrangement mode includes the total number of the sensitive units 121, the number of the sensitive units 121 with the same size, and the arrangement mode of the plurality of sensitive units 121.
The arrangement of the sensing units 121 may be an order in which the sensing units 121 with different sizes in each sensing pixel element 120 are arranged along the second direction (e.g., the y direction shown in the figure). Illustratively, taking the sensing unit 121 as a circle as an example, four sensing pixel elements 120 are respectively arranged on two sides of the substrate 110 along the first direction, four sensing units 121 with different sizes are arranged in each sensing pixel element 120 along the y direction, and there are two sensing units 121 with different sizes. The sensing units 121 have radii of R1, R2, R3, and R4, where R1 is the largest-sized sensing unit and R4 is the smallest-sized sensing unit. The sensing units 121 with different sizes in the sensing pixel element 120 are arranged with mirror symmetry at the arrangement centers, the sensing unit 121 in the middle has the largest size and the radius is R1, the sensing units 121 on the upper and lower edges of the substrate 110 have the smallest size and the radius is R4, and the size of the sensing units 121 on the upper and lower edges of the substrate is smaller. In an actual product, different numbers and sizes of the sensitive units 121 can be distributed between the largest sensitive unit 121 and the smallest sensitive unit 121 according to the flatness requirement in the band, and the higher the flatness requirement in the band is, the greater the number of the distributed sensitive units 121 is.
In the embodiment of the invention, the same setting mode of the sensitive units in any two sensing pixels can ensure that the working frequency of each sensing pixel is consistent with the working bandwidth, and the problems of different frequency responses and uneven sensitivity distribution caused by different setting modes of the sensitive units in each sensing pixel are avoided.
Optionally, with continued reference to fig. 1, in the first direction, a spacing L1 between two adjacent sensing pixels 120 and a middle frequency f of the sensing pixels 120 satisfy L1= f/4.
Wherein, the distance L1 between two adjacent sensing pixels 120 required by different working frequencies and working bandwidths is different.
The distance L1 between two adjacent sensor elements 120 is set to be one fourth of the intermediate frequency of the sensor elements 120, so that the stability and accuracy of output signals of the sensor elements 120 in the working mode can be ensured.
Optionally, with continued reference to fig. 1, the dimension of the thin-film piezoelectric sound pressure sensor 100 in the first direction is L2, and the dimension in the second direction is L3; wherein, L2/L3 is more than or equal to 1 and less than or equal to 4.
Specifically, the distribution number of the sensing pixels 120 in the thin-film piezoelectric sound pressure sensor 100 is determined by the detection requirement and the detection precision, the number of the sensing pixels 120 in the thin-film piezoelectric sound pressure sensor 100 determines the dimension L3 of the thin-film piezoelectric sound pressure sensor 100 in the first direction, and the number of the sensing units 121 in the sensing pixels 120 determines the dimension L3 of the thin-film piezoelectric sound pressure sensor 100 in the y direction. In consideration of the reliability and the process realizability of the thin-film piezoelectric sound pressure sensor 100, the dimension L2 of the thin-film piezoelectric sound pressure sensor 100 in the first direction and the dimension L3 of the thin-film piezoelectric sound pressure sensor 100 in the second direction may be set to satisfy 1 ≤ L2/L3 ≤ 4, that is, the dimension of the thin-film piezoelectric sound pressure sensor 100 in the first direction is greater than the dimension of the thin-film piezoelectric sound pressure sensor in the second direction and is less than 4 times of the dimension of the thin-film piezoelectric sound pressure sensor in the second direction, so that the reliability and the process realizability of the thin-film piezoelectric sound pressure sensor are ensured.
Alternatively, fig. 4 is a schematic structural diagram of a sensing unit provided according to an embodiment of the present invention, and as shown in fig. 4, the sensing unit 121 includes a vacuum chamber 1211 disposed in the substrate 110, and a first electrode 1212, a piezoelectric layer 1213, and a second electrode 1214 stacked on a side of the vacuum chamber 1211 away from the substrate 110; the output electrode 122 includes a first output electrode 1221 and a second output electrode 1222, the first electrode 1212 is electrically connected to the first output electrode 1221, and the second electrode 1214 is electrically connected to the second output electrode 1222.
The piezoelectric layer 1213 can be a structure that deforms and accumulates charges when the sensing unit 121 senses a pressure change. The vacuum chamber 1211 may be a component that senses pressure changes in the sensing unit 121. The first electrode 1212 may be a cathode of the sensing unit 121, and the second electrode 1214 may be an anode of the sensing unit 121; a first output electrode 1221 of the output electrodes 122 can be a negative electrode of the sensing pixel 120, and a second output electrode 1222 can be a positive electrode of the sensing pixel 120. Alternatively, the first electrode 1212 may be a positive electrode of the sensing unit 121, and the second electrode 1214 may be a negative electrode of the sensing unit 121; a first output electrode 1221 of the output electrodes 122 can be the positive pole of the sensor pixel 120, and a second output electrode 1222 can be the negative pole of the sensor pixel 120. The vacuum chamber 1211 and the piezoelectric layer 1213 in the sensing unit 121 sense the pressure change to generate deformation, and the voltage signal of the piezoelectric layer 1213 is output to the first output electrode 1221 and the second output electrode 1222 through the first electrode 1212 and the second electrode 1214, so as to ensure that the sensing unit 121 can sense the pressure signal normally, and output a voltage signal matched with the pressure signal according to the pressure signal.
It should be noted that the first electrode 1212 may further include an output end 1217 of the first electrode, which is used to connect the first electrode 1212 and the first output electrode 1221; the second electrode 1214 can further include a second electrode output 1216 for connecting the second electrode 1214 and the second output electrode 1222, so as to ensure the normal transmission of the voltage signal.
Optionally, and with continued reference to fig. 4, the shape of at least second electrode 1214 and vacuum chamber 1211 includes a circle.
Specifically, the shapes of the second electrode 1214 and the vacuum chamber 1211 can be set to be circular, so that the size structure formed in the manufacturing process is more uniform, the requirement of manufacturing on manufacturing accuracy is reduced, and compared with other geometric structures, the circular structure can obtain the largest vibration area under the action of the same voltage signal, and the sensitivity is better.
Alternatively, with continued reference to fig. 4, the second electrode 1214 and the vacuum chamber 1211 are concentric circles, and the radius R1 'of the second electrode 1214 and the radius R2' of the vacuum chamber 1211 satisfy R1'/R2' =0.7.
Specifically, the different size sensitive units 121 correspond to the vacuum chambers 1211 and the second electrodes 1214 with different sizes. The sensitivity of the second electrode 1214 and the vacuum chamber 1211 for different radius ratios to different voltage signals is different, and is mainly reflected on the deformation amount and the charge distribution amount of the sensing unit 121. When the radius R1 'of the second electrode 1214 and the radius R2' of the vacuum chamber 1211 satisfy R1'/R2' =0.7, the sensitive unit 121 can maintain a high sensitivity.
Optionally, with continued reference to fig. 4, the sensing unit 121 further includes a semiconductor silicon layer 1215 disposed between the vacuum chamber 1211 and the first electrode 1212; the thickness d1 of the semiconductor silicon layer 1215 satisfies 4 [ mu ] m ≦ d1 ≦ 6 [ mu ] m; the first electrode 1212 includes a molybdenum electrode, and a thickness d2 of the first electrode 1212 satisfies 0.1 μm or less and d2 or less and 0.2 μm or less; the peak a of the full width at half maximum curve of the piezoelectric layer 1213 satisfies a <0.3; the second electrode 1214 includes a molybdenum electrode, and a thickness d3 of the second electrode 1214 satisfies 0.1 μm or less and d3 or less and 0.2 μm.
Specifically, the thicker the thickness of the semiconductor silicon layer 1215 and the thickness of the electrode in the sensing unit 121 under the same voltage signal condition, the smaller the amount of deformation exhibited by the sensing unit 121, the lower the sensitivity. In combination with the process realizability and the guarantee of high reliability and high sensitivity, the thickness d1 of the semiconductor silicon layer 1215 may be set to satisfy 4 μm to d1 to 6 μm; the thickness d2 of the first electrode 1212 satisfies that d2 is less than or equal to 0.1 [ mu ] m and less than or equal to 0.2 [ mu ] m; the peak value a of the full width at half maximum curve of the piezoelectric layer 1213 satisfies a <0.3; the thickness d3 of the second electrode 1214 satisfies 0.1 [ mu ] m or less and d3 or less and 0.2 [ mu ] m or less.
In addition, the first electrode 1212 and the second electrode 1214 may include molybdenum electrodes, so as to ensure that the loss in the transmission process of the voltage signal layer is small, and ensure high detection accuracy.
Illustratively, with continued reference to fig. 4, the process of making the sensing unit 121 may be: the structure of the vacuum chamber 1211 is achieved by first etching a recess cavity on the substrate 110 and then by a process of silicon-silicon bonding with the semiconductor silicon layer 1215 under a vacuum environment. A first electrode 1212, a piezoelectric layer 1213, and a second electrode 1214 are formed on the semiconductor silicon layer 1215 by sputtering, photolithography, and wet etching.
The high reliability and the high sensitivity characteristic of the sensitive unit are ensured by adjusting the thickness of the semiconductor silicon layer, the electrode material, the electrode thickness and the parameters of the piezoelectric layer in the sensitive unit.
Optionally, fig. 5 is a schematic side view of a thin film piezoelectric sound pressure sensor according to an embodiment of the present invention, and as shown in fig. 5, the thin film piezoelectric sound pressure sensor 100 further includes a circuit board 200 and an encapsulation layer 300; the circuit board 200 is disposed on a side of the substrate 110 away from the sensor element 120, and the output electrode 122 is electrically connected to the circuit board 200; the packaging layer 300 is disposed on a side of the sensor pixel 120 away from the substrate 110, the packaging layer 300 covers the plurality of sensor pixels 120, and a thickness d4 of the packaging layer 300 is 0.95mm or more and d4 or less and 1.05 mm or less.
The Circuit Board 200 may be a Printed Circuit Board (PCB) for extracting and processing the voltage signal. The voltage signal output from the output electrode 122 is transmitted to the circuit board 200, and then transmitted to the imaging system through the circuit board 200.
The encapsulation layer 300 is used to ensure water tightness and performance stability of the thin film piezoelectric acoustic pressure sensor 100 during underwater operation.
For example, the material of the encapsulation layer 300 may be polyurethane, and the thin film piezoelectric acoustic pressure sensor 100 is integrally molded by wrapping and curing the same. Since the encapsulation layer 300 acts simultaneously at the resonant operating frequency, the material, thickness, residual stress, etc. of the encapsulation layer 300 all affect the resonant frequency. Therefore, on the premise of ensuring the material components and the unchanged curing condition, the thickness d4 of the packaging layer 300 is ensured to meet the requirement that d4 is more than or equal to 0.95mm and less than or equal to 1.05 mm to ensure the consistency of the thickness of the packaging layer 300.
By limiting the connection mode of the circuit board and the thickness of the packaging layer, the water tightness of the thin film piezoelectric sound pressure sensor is ensured, and meanwhile, the signal to noise ratio of the thin film piezoelectric sound pressure sensor is improved.
According to the embodiment of the invention, the plurality of sensing pixels are arranged in the thin film piezoelectric sound pressure sensor, the plurality of sensing units with different sizes are arranged in each sensing pixel, and the plurality of resonant frequency points are realized through the sensing units with different sizes, so that the bandwidth of the thin film piezoelectric sound pressure sensor working in a resonant state is increased, the thin film piezoelectric sound pressure sensor is ensured to have high sensitivity and high bandwidth working modes, and the detection accuracy is ensured.
Based on the same inventive concept, an embodiment of the present invention further provides a detection imaging apparatus, and specifically, fig. 6 is a schematic structural diagram of the detection imaging apparatus provided in the embodiment of the present invention. As shown in fig. 6, the apparatus includes a thin film piezoelectric acoustic pressure sensor 100; the piezoelectric acoustic pressure sensor comprises a transmitting transducer 400 and an imager 401, wherein the thin film piezoelectric acoustic pressure sensor 100 is arranged on the surface of the imager 401 and is electrically connected with the imager 401; the transmitting transducer 400 is used to emit a probe sound wave; the film piezoelectric sound pressure sensor 100 is configured to receive a sound wave signal reflected by an object to be detected 402, convert the sound wave signal into a voltage signal, and feed back the voltage signal to the imager 401; the imager 401 is configured to determine detection information of the object to be detected 402 according to the voltage signal.
Specifically, the transmitting transducer 400 in the detection imaging device emits a detection sound wave, when the detection imaging device encounters the object 402 to be detected, the sound wave is reflected, the thin film piezoelectric sound pressure sensor 100 of the detection imaging device receives the sound wave reflected by the object 402 to be detected, and the information such as the size, the shape, the distance and the like of the object 402 to be detected is restored through an imaging algorithm according to the sound pressure, the phase and the like of the sound wave.
Alternatively, as shown in fig. 7, the detection imaging apparatus includes a plurality of thin film piezoelectric acoustic pressure sensors 100;
a plurality of thin film piezoelectric acoustic pressure sensors 100 are arrayed on the surface of the imager 401.
Specifically, limited by the process of the thin film piezoelectric acoustic pressure sensor 100, the number of sensing pixels 120 of a single thin film piezoelectric acoustic pressure sensor 100 is limited, and a plurality of thin film piezoelectric acoustic pressure sensors 100 are arrayed on the surface of the imager 401, so that a higher resolution can be obtained, and the expansion of the sensing pixels 120 can be realized.
According to the detection imaging device, the thin film piezoelectric sound pressure sensors with multiple resonance frequency points are arrayed on the surface of the imaging instrument, so that the sensitivity of the detection imaging device is improved, and the accuracy of a detection imaging system is improved.
The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (13)
1. A film piezoelectric sound pressure sensor is characterized by comprising a substrate and a plurality of sensing pixels positioned on one side of the substrate, wherein the sensing pixels are arranged along a first direction, and the first direction is parallel to the plane of the substrate;
the sensing pixel comprises a plurality of sensing units and an output electrode, wherein the sensing units are electrically connected with the output electrode; a plurality of sensitive units in the same sensing pixel are arranged along a second direction, and the second direction is parallel to the plane of the substrate and is intersected with the first direction;
in the same sensing pixel, the sizes of at least two sensing units are different.
2. The thin film piezoelectric acoustic pressure sensor according to claim 1, wherein the number of the sensing units with different sizes is the same in the same sensing pixel.
3. The thin film piezoelectric sound pressure sensor according to claim 1, wherein in the same sensing pixel, the sensing units with the same size are arranged in series or in parallel;
the sensitive units with different sizes are arranged in parallel.
4. The thin film piezoelectric acoustic pressure sensor according to claim 1, wherein the sensing unit comprises a vacuum chamber disposed in the substrate, and a first electrode, a piezoelectric layer and a second electrode stacked on a side of the vacuum chamber away from the substrate;
the output electrode comprises a first output electrode and a second output electrode, the first electrode is electrically connected with the first output electrode, and the second electrode is electrically connected with the second output electrode.
5. The thin film piezoelectric acoustic pressure sensor of claim 4, wherein at least the second electrode and the vacuum chamber have a shape comprising a circle.
6. The thin-film piezoelectric acoustic pressure sensor according to claim 5, wherein the second electrode and the vacuum chamber have a concentric structure, and a radius R1 'of the second electrode and a radius R2' of the vacuum chamber satisfy R1'/R2' =0.7.
7. The thin film piezoelectric acoustic pressure sensor of claim 4, wherein the sensing unit further comprises a semiconductor silicon layer disposed between the vacuum chamber and the first electrode;
the thickness d1 of the semiconductor silicon layer meets the condition that d1 is less than or equal to 4 mu m and less than or equal to 6 mu m;
the first electrode comprises a molybdenum electrode, and the thickness d2 of the first electrode meets the condition that d2 is less than or equal to 0.1 mu m and less than or equal to 0.2 mu m;
the peak value a of the full width at half maximum curve of the piezoelectric layer satisfies a <0.3;
the second electrode comprises a molybdenum electrode, and the thickness d3 of the second electrode is less than or equal to 0.1 mu m and less than or equal to d3 and less than or equal to 0.2 mu m.
8. The thin film piezoelectric sound pressure sensor according to claim 1, wherein the sensing units in any two of the sensing pixels are arranged in the same manner;
the setting mode comprises the total number of the sensitive units, the number of the sensitive units with the same size and the arrangement mode of the sensitive units.
9. The thin-film piezoelectric acoustic pressure sensor according to claim 1, wherein a distance L1 between adjacent two of the sensing pixels and a center frequency f of the sensing pixels in the first direction satisfy L1= f/4.
10. The thin film piezoelectric acoustic pressure sensor according to claim 1, wherein the thin film piezoelectric acoustic pressure sensor has a dimension L2 in the first direction and a dimension L3 in the second direction;
wherein, L2/L3 is more than or equal to 1 and less than or equal to 4.
11. The thin film piezoelectric acoustic pressure sensor according to claim 1, further comprising a circuit board and an encapsulation layer;
the circuit board is arranged on one side of the substrate far away from the sensing pixel, and the output electrode is electrically connected with the circuit board;
the packaging layer is arranged on one side, far away from the substrate, of the sensing pixel, the packaging layer covers the sensing pixels, and the thickness d4 of the packaging layer is larger than or equal to 0.95mm and smaller than or equal to d4 and smaller than or equal to 1.05 mm.
12. A probe imaging apparatus comprising the thin film piezoelectric acoustic pressure sensor according to any one of claims 1 to 11;
the thin film piezoelectric sound pressure sensor is arranged on the surface of the imager and is electrically connected with the imager;
the transmitting transducer is used for emitting detection sound waves;
the thin film piezoelectric sound pressure sensor is used for receiving a sound wave signal reflected by an object to be detected, converting the sound wave signal into a voltage signal and feeding the voltage signal back to the imager;
the imager is used for determining the detection information of the object to be detected according to the voltage signal.
13. The detection imaging apparatus according to claim 12, wherein the detection imaging apparatus includes a plurality of the thin film piezoelectric acoustic pressure sensors;
and the plurality of thin film piezoelectric sound pressure sensors are arranged on the surface of the imaging instrument in an array mode.
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