A multi-layer internally connected piezoelectric thin film sensor and a preparation method thereof

Abstract

The present invention relates to a multi-layer internally connected piezoelectric thin film sensor and a preparation method thereof, belonging to the technical field of thin film sensors. The piezoelectric thin film sensor includes n piezoelectric layers and n + 1 electrode layers stacked, where n ≥ 2; the piezoelectric layers are located between two adjacent electrode layers; the thin film sensor further includes a bridging part, the bridging part is located inside two adjacent piezoelectric layers, the bridging part connects two alternating electrode layers, and an insulating region is provided between the electrode layer located between two adjacent piezoelectric layers and the bridging part, so that two adjacent piezoelectric layers are connected in parallel. By arranging the bridging part inside the piezoelectric thin film sensor, the present invention realizes the parallel connection of multiple piezoelectric layers from the inside of the piezoelectric thin film sensor, without external leads, and does not change the external shape of the thin film sensor, having the advantages of simple preparation, easy integration, and large displacement amount.

Description

Technical Field

[0001] The present invention belongs to the technical field of thin film sensors, and particularly relates to a multi-layer internally connected piezoelectric thin film sensor and a preparation method thereof. Background Art

[0002] Piezoelectric thin film sensors are widely used in fields such as aerospace, geological exploration, and mobile communication. With the continuous improvement of the requirements for high-power piezoelectric thin film sensors, thin film sensors are developing in the direction of small volume, low driving voltage, large displacement, and easy integration, and the requirements for the piezoelectric performance of piezoelectric thin film sensors are also getting higher and higher.

[0003] In related technologies, a multi-layer piezoelectric thin film with an alternating stack of electrode layers and piezoelectric layers is proposed. Each layer of electrode is separately led out, and then the alternate electrodes are connected with the same voltage polarity (for example, the electrodes of the first layer and the third layer are connected to the positive voltage through lead wires, and the electrodes of the second layer and the fourth layer are connected to the negative voltage through lead wires), so as to realize the parallel connection of the multi-layer piezoelectric thin film. The parallel structure of the multi-layer piezoelectric thin film can obtain a large displacement at a lower voltage. However, although this method of leading out the electrodes is easy to prepare, it changes the external shape of the piezoelectric thin film sensor and is not conducive to integrated setting.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a multi-layer internally connected piezoelectric thin film sensor and a preparation method thereof.

[0006] In a first aspect of the present invention, a multi-layer internally connected piezoelectric thin film sensor is proposed. The piezoelectric thin film sensor includes n layers of piezoelectric layers and n + 1 layers of electrode layers arranged in a stack, where n ≥ 2; the piezoelectric layers are located between two adjacent electrode layers.

[0007] The thin film sensor further includes a bridging part. The bridging part is located inside two adjacent piezoelectric layers. The bridging part connects two alternate electrode layers, and an insulating region is provided between the electrode layer located between two adjacent piezoelectric layers and the bridging part, so that two adjacent piezoelectric layers are connected in parallel.

[0008] Further optionally, the number of the bridging parts is n - 1.

[0009] Further optionally, when n = 2, the thin film sensor includes one bridging part, and the center of the bridging part coincides with the centers of the first piezoelectric layer and the second piezoelectric layer.

[0010] Further optionally, when n > 2, two piezoelectric layers connected in parallel form a piezoelectric layer group, and two bridging parts corresponding to two adjacent piezoelectric layer groups are arranged in a staggered manner.

[0011] Further optionally, the material of the bridging portion is the same as that of the electrode layer.

[0012] Further optionally, an insulating layer is provided in the insulating region, and the material of the insulating layer is the same as that of the piezoelectric layer.

[0013] Further optionally, a stepped structure is formed between the nth piezoelectric layer and the nth electrode layer;

[0014] In the test state, the test device applies a voltage to the thin film sensor through the stepped structure.

[0015] Further optionally, the stepped structure is a misaligned area formed between the nth piezoelectric layer and the nth electrode layer, and the outer edge of the nth electrode layer extends beyond the outer edge of the (n + 1)th electrode layer.

[0016] A second aspect of the present invention provides a method for manufacturing a multi-layer interconnected piezoelectric thin film sensor, the manufacturing method including: generating electrode layers and piezoelectric layers layer by layer on the bottom surface of the device substrate, and the piezoelectric layers are located between the electrode layers; the manufacturing method further includes:

[0017] Before generating the kth piezoelectric layer on the kth electrode layer, first set a first mask on the kth electrode layer, and the size of the first mask is smaller than the size of the kth electrode layer; then generate the kth piezoelectric layer on the kth electrode layer, where k ∈ [1, n - 1];

[0018] Before generating the (k + 1)th electrode layer on the kth piezoelectric layer, first set a second mask on the first mask, and the size of the second mask is larger than the size of the first mask and smaller than the size of the kth piezoelectric layer; then generate the (k + 1)th electrode layer on the kth piezoelectric layer.

[0019] Further optionally, the manufacturing method further includes:

[0020] When k + 1 < n, before generating the (k + 1)th piezoelectric layer on the (k + 1)th electrode layer, first remove the second mask and keep the first mask; generate the (k + 1)th piezoelectric layer on the (k + 1)th electrode layer, and the area after removing the second mask and the (k + 1)th piezoelectric layer are simultaneously sputtered and grown into one body; then remove the first mask, and generate the (k + 2)th electrode layer on the (k + 1)th piezoelectric layer, and the area after removing the first mask and the (k + 2)th electrode layer are simultaneously sputtered and grown into one body;

[0021] When k + 1 = n, before the (k + 1)-th piezoelectric layer is formed on the (k + 1)-th electrode layer, first remove the second mask plate, keep the first mask plate, and set a third mask plate inside the edge of the (k + 1)-th electrode layer. The third mask plate is annular; then form the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer. The (k + 1)-th piezoelectric layer is located between the first mask plate and the third mask plate, and the area after removing the second mask plate and the (k + 1)-th piezoelectric layer are simultaneously sputtered and grown into one body; then remove the first mask plate, keep the third mask plate, form the (k + 2)-th electrode layer on the (k + 1)-th piezoelectric layer, and the area after removing the first mask plate and the (k + 2)-th electrode layer are simultaneously sputtered and grown into one body, and finally remove the third mask plate.

[0022] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art: The present invention realizes the parallel connection of multiple piezoelectric layers by setting a bridging part inside the piezoelectric thin film sensor. At the same time, by setting a stepped structure between the n-th piezoelectric layer and the n-th electrode layer, during the test state, the test device can directly apply a voltage to the piezoelectric thin film sensor through the stepped structure for rapid testing, without external leads, and without changing the external shape of the thin film sensor, having the advantages of simple preparation and large displacement.

[0023] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings. Description of the Drawings

[0024] As a part of the present invention, the accompanying drawings are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention, but do not constitute an improper limitation to the present invention. Obviously, the accompanying drawings in the following description are only some embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0025] Figure 1 is a schematic diagram of a piezoelectric thin film sensor with two piezoelectric layers connected in parallel shown according to an exemplary embodiment.

[0026] Figure 2 is a schematic diagram of a piezoelectric thin film sensor with three piezoelectric layers connected in parallel shown according to an exemplary embodiment.

[0027] Figure 3 is a schematic diagram of a piezoelectric thin film sensor with four piezoelectric layers connected in parallel shown according to an exemplary embodiment.

[0028] Figure 4 is a schematic diagram of a piezoelectric thin film sensor with four piezoelectric layers connected in parallel shown according to an exemplary embodiment.

[0029] Figure 5It is a process diagram for preparing a piezoelectric thin film sensor with two piezoelectric layers connected in parallel shown according to an exemplary embodiment.

[0030] Wherein: 11 - the first piezoelectric layer; 12 - the second piezoelectric layer; 13 - the third piezoelectric layer; 14 - the fourth piezoelectric layer; 101 - the first piezoelectric layer group; 102 - the second piezoelectric layer group; 103 - the third piezoelectric layer group; 21 - the first electrode layer; 22 - the second electrode layer; 23 - the third electrode layer; 24 - the fourth electrode layer; 25 - the fifth electrode layer; 3 - the misalignment region; 4 - the bridging portion; 41 - the first bridging portion; 42 - the second bridging portion; 43 - the third bridging portion; 5 - the insulation region.

[0031] It should be noted that these drawings and text descriptions are not intended to limit the scope of the concept of the present invention in any way, but to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "contacted", "communicated" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In the related art, for a multi-layer piezoelectric thin film with electrode layers and piezoelectric layers alternately stacked, by separately leading out each layer of electrode and then connecting the electrodes with the same voltage polarity alternately (such as connecting the first layer and the third layer electrodes to the positive voltage through lead wires, and connecting the second layer and the fourth layer electrodes to the negative voltage through lead wires), the parallel connection of the multi-layer piezoelectric thin film is achieved. The parallel structure of the multi-layer piezoelectric thin film can obtain a large displacement at a lower voltage. However, although this method of leading out electrodes is convenient to prepare, it changes the external shape of the piezoelectric thin film sensor and is not conducive to integrated setting.

[0035] To solve the above technical problems, this embodiment proposes a multi-layer internally connected piezoelectric thin film sensor. The piezoelectric thin film sensor includes n piezoelectric layers and n + 1 electrode layers arranged in a stacked manner, where n ≥ 2; the piezoelectric layers are located between two adjacent electrode layers; the thin film sensor further includes a bridging portion, the bridging portion is located inside two adjacent piezoelectric layers, the bridging portion connects two alternating electrode layers, and an insulating region is provided between the electrode layer located between two adjacent piezoelectric layers and the bridging portion, so that two adjacent piezoelectric layers are arranged in parallel. In this embodiment, multiple piezoelectric layers are connected in parallel by providing a bridging portion inside the piezoelectric thin film sensor, without changing the external shape of the thin film sensor, which is easy to integrate and has the advantages of simple preparation and large displacement.

[0036] The technical solution of this embodiment will be elaborated in detail below with reference to the accompanying drawings.

[0037] According to an exemplary embodiment of the present invention, referring to Figures 1 - 4 , this embodiment proposes a multi-layer internally connected piezoelectric thin film sensor. The piezoelectric thin film sensor includes n piezoelectric layers and n + 1 electrode layers arranged in a stacked manner, where n ≥ 2; the piezoelectric layers are located between two adjacent electrode layers. The piezoelectric layers and the electrode layers can be directly grown in situ on the end face of the device substrate. The material of the electrode layer includes but is not limited to Ag, Au, Al, Ti, Pt, W, Mo, etc. The thickness of the electrode layer is between 0 and 10 μm, and the thickness of the electrode layer is not 0. The shape and size of the electrode layer are not limited and can be determined according to the shape and size of the end face of the device substrate. For example, the shape of the electrode layer is circular, and the diameter range of the electrode layer is 0.5 to 10 cm. The material of the piezoelectric layer includes but is not limited to PZT, ZnO, AlN, KNN, etc., and its thickness is 0 to 20 μm, and the thickness of the piezoelectric layer is not 0. The shape and size of the piezoelectric layer are not limited and can be determined according to the size and shape of the electrode layer where it is located.

[0038] The thin film sensor further includes a bridging portion 4. The bridging portion 4 is located inside adjacent two electrode layers. The bridging portion connects two electrode layers spaced apart, and an insulating region 5 is provided between the electrode layer between adjacent two piezoelectric layers and the bridging portion 4 to prevent a short circuit between the electrode layer between adjacent two piezoelectric layers and the bridging portion 4 when the piezoelectric thin film sensor is in operation, so that adjacent two piezoelectric layers are connected in parallel. The bridging portion 4 is made of a material with conductive properties. The material of the bridging portion 4 can be the same as or different from that of the electrode layer. Preferably, the material of the bridging portion 4 is the same as that of the electrode layer to simplify the manufacturing process of the piezoelectric thin film sensor. An insulating layer can be provided in the insulating region 5 provided between the electrode layer between adjacent two piezoelectric layers and the bridging portion 4. The material of the insulating layer can be the same as or different from that of the piezoelectric layer. Preferably, the material of the insulating layer is the same as that of the piezoelectric layer to simplify the manufacturing process of the piezoelectric thin film sensor. The structure of the bridging portion 4 is not limited in this embodiment. In one example, referring to Figures 1 - 4 , the bridging portion 4 is cylindrical and is located inside adjacent two piezoelectric layers and connects two electrode layers spaced apart. Of course, the shape of the bridging portion 4 can also be sheet-like or other shapes.

[0039] It should be noted that two electrode layers spaced apart in this embodiment means that there is also an electrode layer between the two electrode layers. Referring to Figure 3 and Figure 4 , when the number of piezoelectric layers is four, the number of electrode layers is five. Then the first electrode layer 21 and the third electrode layer 23 are spaced apart, the second electrode layer 22 and the fourth electrode layer 24 are spaced apart, and the third electrode layer 23 and the fifth electrode layer 25 are spaced apart. When the number of piezoelectric layers is other numbers, two electrode layers spaced apart can be determined according to the same rule.

[0040] In some embodiments, the number of the bridging portions 4 is related to the number of piezoelectric layers. When the number of piezoelectric layers is n layers, the number of the bridging portions 4 is n - 1. Referring to Figure 1 , when the number of piezoelectric layers is two, the number of the bridging portions 4 is one. The bridging portion 4 is located inside the adjacent first piezoelectric layer 11 and second piezoelectric layer 12, and the first electrode layer 21 and the third electrode layer 23 spaced apart are respectively connected to the bridging portion 4. An insulating region 5 is provided between the second electrode layer 22 between the adjacent first piezoelectric layer 11 and second piezoelectric layer 12 and the bridging portion 4 to connect the first piezoelectric layer 11 and the second piezoelectric layer 12 in parallel.

[0041] Referring to Figure 2, when the number of piezoelectric layers is three, the number of bridging parts 4 is two, namely the first bridging part 41 and the second bridging part 42. Among them, the first bridging part 41 is inside the adjacent first piezoelectric layer 11 and second piezoelectric layer 12, and the alternating first electrode layer 21 and third electrode layer 23 are respectively connected to the first bridging part 41. An insulating region 5 is provided between the second electrode layer 22 located between the adjacent first piezoelectric layer 11 and second piezoelectric layer 12 and the first bridging part 41 to parallelize the first piezoelectric layer 11 and the second piezoelectric layer 12; the second bridging part 42 is inside the adjacent second piezoelectric layer 12 and third piezoelectric layer 13, and the alternating second electrode layer 22 and fourth electrode layer 24 are respectively connected to the second bridging part 42. An insulating region 5 is provided between the third electrode layer 23 located between the adjacent second piezoelectric layer 12 and third piezoelectric layer 13 and the second bridging part 42 to parallelize the second piezoelectric layer 12 and the third piezoelectric layer 13.

[0042] Referring to Figure 3 and Figure 4 , when the number of piezoelectric layers is four, the number of bridging parts 4 is three, namely the first bridging part 41, the second bridging part 42 and the third bridging part 43. Among them, the first bridging part 41 is inside the adjacent first piezoelectric layer 11 and second piezoelectric layer 12, and the alternating first electrode layer 21 and third electrode layer 23 are respectively connected to the first bridging part 41. An insulating region 5 is provided between the second electrode layer 22 located between the adjacent first piezoelectric layer 11 and second piezoelectric layer 12 and the first bridging part 41 to parallelize the first piezoelectric layer 11 and the second piezoelectric layer 12; the second bridging part 42 is inside the adjacent second piezoelectric layer 12 and third piezoelectric layer 13, and the alternating second electrode layer 22 and fourth electrode layer 24 are respectively connected to the second bridging part 42. An insulating region 5 is provided between the third electrode layer 23 located between the adjacent second piezoelectric layer 12 and third piezoelectric layer 13 and the second bridging part 42 to parallelize the second piezoelectric layer 12 and the third piezoelectric layer 13. The third bridging part 43 is inside the adjacent third piezoelectric layer 13 and fourth piezoelectric layer 14, and the alternating third electrode layer 23 and fifth electrode layer 25 are respectively connected to the third bridging part 43. An insulating region 5 is provided between the fourth electrode layer 24 located between the adjacent third piezoelectric layer 13 and fourth piezoelectric layer 14 and the third bridging part 43 to parallelize the third piezoelectric layer 13 and the fourth piezoelectric layer 14.

[0043] And so on, when the number of piezoelectric layers is five, six or other number of layers n, the number of bridging parts 4 is 4, 5 or n - 1.

[0044] The setting position of the bridging part 4 in this embodiment is different according to the different number of piezoelectric layers.

[0045] In one example, referring to Figure 1 , when n = 2, the number of layers of the piezoelectric layer is two layers, and the thin film sensor includes a bridging portion 4 located at a preset area inside the thin film sensor. The position of the preset area is not limited in this embodiment, and it can be any area inside the first piezoelectric layer 11 and the second piezoelectric layer 12. Exemplarily, the center of the preset area coincides with the centers of the first piezoelectric layer 11 and the second electrode layer 22, that is, the center of the bridging portion coincides with the centers of the first piezoelectric layer and the second piezoelectric layer, and the bridging portion is located at the center position of the piezoelectric thin film sensor.

[0046] In one example, when n > 2, two layers of piezoelectric layers arranged in parallel form a piezoelectric layer group, and two bridging portions 4 corresponding to two adjacent piezoelectric layer groups are arranged in a staggered manner to achieve parallel connection of every two adjacent piezoelectric layers. The plane where the first electrode layer 21 is located is set as the preset plane. The staggered arrangement in this embodiment means that the projections of two adjacent bridging portions 4 on the preset plane do not overlap. Referring to Figure 2 , when the number of layers of the piezoelectric layer is three, the piezoelectric thin film sensor includes a first bridging portion 41 and a second bridging portion 42. The first piezoelectric layer 11 and the second piezoelectric layer 12 form a first piezoelectric layer group 101, and the first bridging portion 41 corresponds to the first piezoelectric layer group 101; the second piezoelectric layer 12 and the third piezoelectric layer 13 form a second piezoelectric layer group 102, and the second bridging portion 42 corresponds to the second piezoelectric layer group 102. The first piezoelectric layer group 101 and the second piezoelectric layer group 102 are adjacent, and the first bridging portion 41 and the second bridging portion 42 are arranged in a staggered manner. Referring to Figure 3 and Figure 4 , when the number of layers of the piezoelectric layer is four, the piezoelectric thin film sensor includes a first bridging portion 41, a second bridging portion 42, and a third bridging portion 43. The first piezoelectric layer 11 and the second piezoelectric layer 12 form a first piezoelectric layer group 101, and the first bridging portion 41 corresponds to the first piezoelectric layer group 101; the second piezoelectric layer 12 and the third piezoelectric layer 13 form a second piezoelectric layer group 102, and the second bridging portion 42 corresponds to the second piezoelectric layer group 102; the third piezoelectric layer 13 and the fourth piezoelectric layer 14 form a third piezoelectric layer group 103, and the third bridging portion 43 corresponds to the third piezoelectric layer group 103; the first piezoelectric layer group 101 and the second piezoelectric layer group 102 are adjacent, the second piezoelectric layer group 102 and the third piezoelectric layer group 103 are adjacent, the first bridging portion 41 and the second bridging portion 42 are arranged in a staggered manner, and the second bridging portion 42 and the third bridging portion 43 are arranged in a staggered manner.

[0047] In this embodiment, the two bridging portions corresponding to non-adjacent piezoelectric layer groups may be arranged in a staggered manner or in a corresponding manner. Referring to Figure 3, the first piezoelectric layer group 101 and the third piezoelectric layer group 103 are non-adjacent piezoelectric layer groups, and the first bridging portion 41 and the third bridging portion 43 are correspondingly arranged, that is, the projections of the first bridging portion 41 and the second bridging portion 42 on a preset plane overlap. Refer to Figure 4 , the first piezoelectric layer group 101 and the third piezoelectric layer group 103 are non-adjacent piezoelectric layer groups, and the first bridging portion 41 and the third bridging portion 43 are arranged in a staggered manner, that is, the projections of the first bridging portion 41 and the third bridging portion 43 on a preset plane do not overlap.

[0048] According to an exemplary embodiment of the present invention, a stepped structure is formed between the nth piezoelectric layer and the nth electrode layer of the piezoelectric film sensor in this embodiment. In the test state, the test device applies a voltage to the film sensor through the stepped structure, thereby realizing rapid testing of the piezoelectric film sensor without external leads and being easy to integrate. In one example, refer to Figures 1 - 4 , the stepped structure is a staggered area 3 formed between the outer edge of the nth piezoelectric layer and the nth electrode layer, and the outer edge of the nth electrode layer extends beyond the outer edge of the (n + 1)th electrode layer. The structure of the test device is not limited in this embodiment. In one example, the test device includes a coaxial probe. In the test state, the positive electrode of the coaxial probe of the test device abuts against the (n + 1)th electrode layer, and the negative electrode of the coaxial probe abuts against the nth electrode layer through the staggered area 3. Refer to Figure 1 , when there are two piezoelectric layers, the stepped structure is a staggered area 3 formed between the outer edge of the second piezoelectric layer 12 and the outer edge of the second electrode layer 22, and the outer edge of the second electrode layer 22 extends beyond the outer edge of the third electrode layer 23. In the test state, the positive electrode of the coaxial probe of the test device abuts against the third electrode layer 23, and the negative electrode of the coaxial probe abuts against the second electrode layer 22 through the staggered area 3. Refer to Figure 2 , when there are three piezoelectric layers and four electrode layers, the stepped structure is a staggered area 3 formed between the outer edge of the third piezoelectric layer 13 and the outer edge of the third electrode layer 23, and the outer edge of the third electrode layer 23 extends beyond the outer edge of the fourth electrode layer 24. In the test state, the positive electrode of the coaxial probe of the test device abuts against the fourth electrode layer 24, and the negative electrode of the coaxial probe abuts against the third electrode layer 23 through the staggered area 3. Refer to Figure 3 , when there are four piezoelectric layers and five electrode layers, the stepped structure is a staggered area 3 formed between the outer edge of the fourth piezoelectric layer 14 and the outer edge of the fourth electrode layer 24, and the outer edge of the fourth electrode layer 24 extends beyond the outer edge of the fifth electrode layer 25. In the test state, the positive electrode of the coaxial probe of the test device abuts against the fifth electrode layer 25, and the negative electrode of the coaxial probe abuts against the fourth electrode layer 24 through the staggered area 3.

[0049] In this embodiment, a bridging part is arranged inside the piezoelectric thin film sensor to achieve the parallel connection of multiple piezoelectric layers. At the same time, a stepped structure is arranged between the nth piezoelectric layer and the nth electrode layer. In the test state, the testing device can directly apply a voltage to the piezoelectric thin film sensor through the stepped structure for rapid testing without external leads, without changing the external shape of the thin film sensor, and has the advantages of simple preparation and large displacement.

[0050] According to an exemplary embodiment of the present invention, this embodiment proposes a preparation method for a multi-layer internally connected piezoelectric thin film sensor. The preparation of the piezoelectric thin film sensor in this embodiment can be realized by magnetron sputtering method with the assistance of a mask plate. When it is applied to a piezoelectric thin film sensor with parallel connection of multiple piezoelectric layers, the structure will be different due to different connection methods between different piezoelectric layers.

[0051] The preparation method of this embodiment includes: generating electrode layers and piezoelectric layers layer by layer on the bottom surface of the device substrate, and the piezoelectric layers are located between the electrode layers. The preparation method also includes:

[0052] Before generating the kth piezoelectric layer on the kth electrode layer, first set a first mask plate on the kth electrode layer, and then generate the kth piezoelectric layer on the kth electrode layer. The first mask plate is located inside the kth piezoelectric layer, k ∈ [1, n - 1];

[0053] Before generating the (k + 1)th electrode layer on the kth piezoelectric layer, first set a second mask plate on the first mask plate. The size of the second mask plate is larger than that of the first mask plate; generate the (k + 1)th electrode layer on the kth piezoelectric layer, and the second mask plate is located inside the (k + 1)th electrode layer.

[0054] Among them, the area where the first mask plate is located is used to form a bridging part, and the area where the second mask plate is located is used to form an isolation area between the electrode layer and the bridging part.

[0055] Further optionally, the preparation method also includes:

[0056] When k + 1 < n, before forming the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, first remove the second mask plate and keep the first mask plate; form the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, with the first mask plate located inside the (k + 1)-th piezoelectric layer, and the area after removing the second mask plate grows integrally with the (k + 1)-th piezoelectric layer; then remove the first mask plate and form the (k + 2)-th electrode layer on the (k + 1)-th piezoelectric layer, and the area after removing the first mask plate sputter-grows integrally with the (k + 2)-th electrode layer at the same time; when k + 1 = n, before forming the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, first remove the second mask plate and keep the first mask plate, and set a third mask plate inside the edge of the (k + 1)-th electrode layer, and the third mask plate is annular; then form the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, with the (k + 1)-th piezoelectric layer located between the first mask plate and the third mask plate, and the area after removing the second mask plate grows integrally with the (k + 1)-th piezoelectric layer; then remove the first mask plate and keep the third mask plate, form the (k + 2)-th electrode layer on the (k + 1)-th piezoelectric layer, and the area after removing the first mask plate sputter-grows integrally with the (k + 2)-th electrode layer at the same time, and finally remove the third mask plate. Among them, the area where the third mask plate is located is used to form a stepped portion.

[0057] The preparation method of this embodiment will be introduced in detail below in combination with specific examples.

[0058] The preparation method of this embodiment will be introduced in detail below by taking a piezoelectric thin film sensor with two piezoelectric layers as an example, and piezoelectric thin film sensors with three, four, five, six or n piezoelectric layers are prepared by repeating relevant steps.

[0059] Refer to Figure 5 the process diagram, and the steps of the preparation method of the piezoelectric thin film Chang'an sensor with two piezoelectric layers connected in parallel are as follows:

[0060] (1) The first electrode layer is directly grown in situ on the end face of the device substrate by magnetron sputtering. The materials of the electrode layer include but are not limited to Ag, Au, Al, Ti, Pt, W, Mo, etc. The sputtering thickness is generally 0 - 10 μm, not 0, and the diameter can be determined according to the size of the device substrate, generally 0.5 - 10 cm. After sputtering, as Figure 5 (a) shown.

[0061] (2) Before sputtering the first piezoelectric layer, place a circular mask plate a (i.e., the first mask plate) on the first electrode layer, and then sputter the first piezoelectric layer on the first electrode layer. The diameter of the mask plate a is determined according to the diameter of the first electrode layer, about 10% - 20% of the diameter of the first electrode layer. The piezoelectric materials of the piezoelectric layer include but are not limited to PZT, ZnO, AlN, KNN, etc., and its thickness is 0 - 20 μm, not 0. After sputtering, asFigure 5 as shown in (b).

[0062] (3) Before sputtering the second electrode layer, the mask plate a remains stationary, and a circular mask plate b (i.e., the second mask plate) is placed thereon. Then, the second electrode layer is sputtered on the first piezoelectric layer. The diameter of the mask plate b is 1.2 - 1.5 times that of the mask plate a. The material and size of the second electrode layer are the same as those of the first electrode layer. After sputtering, it is as shown in Figure 5 (c).

[0063] (4) Before sputtering the second piezoelectric layer, the mask plate b is removed, and a ring mask plate c (i.e., the third mask plate) is placed above the second electrode layer while the mask plate a remains stationary. Then, the second piezoelectric layer is sputtered on the second electrode layer. The outer diameter of the mask plate c is the same as that of the second electrode layer, and the inner diameter is 60% - 80% of the outer diameter to achieve a stepped structure. The area where the mask plate b is removed is sputtered and grown simultaneously with the second piezoelectric layer to form an integral body. The area where the mask plate b is removed forms an insulating region. After sputtering, it is as shown in Figure 5 (d).

[0064] (5) Before sputtering the third electrode layer, the mask plate a is removed while the mask plate c remains stationary. Then, the third electrode layer is sputtered on the second piezoelectric layer. The material of the third electrode layer is the same as that of the first electrode layer and the second electrode layer, and the diameter is the same as the inner diameter of the mask plate c. The area where the mask plate a is removed is sputtered and grown simultaneously with the third electrode layer to form an integral body. The area where the mask plate a is removed forms a bridging part to achieve the internal connection between the first electrode layer and the third electrode layer. After sputtering, the mask plate c is removed, and the area where the mask plate c is removed forms a stepped part, as shown in Figure 5 (e). That is, the preparation of the two - layer piezoelectric thin - film parallel structure is completed.

[0065] The above - mentioned are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art of this patent, without departing from the scope of the technical solution of the present invention, can make some changes or modifications using the above - mentioned technical content to obtain equivalent embodiments of equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the present invention's solution.

Claims

1. A multi-layer internally connected piezoelectric thin film sensor, characterized in that, The piezoelectric thin film sensor includes n piezoelectric layers and n + 1 electrode layers stacked, where n ≥ 2; the piezoelectric layers are located between two adjacent electrode layers; The thin film sensor further includes a bridging portion, the bridging portion is located inside two adjacent piezoelectric layers, the bridging portion connects two alternating electrode layers, and an insulating region is provided between the electrode layer located between two adjacent piezoelectric layers and the bridging portion, so that two adjacent piezoelectric layers are arranged in parallel; The preparation method of the multi-layer interconnected piezoelectric thin film sensor includes: generating electrode layers and piezoelectric layers layer by layer on the bottom end surface of the device substrate, and the piezoelectric layers are located between the electrode layers; the preparation method further includes: Before generating the k-th piezoelectric layer on the k-th electrode layer, first set a first mask on the k-th electrode layer, and the size of the first mask is smaller than the size of the k-th electrode layer; then generate the k-th piezoelectric layer on the k-th electrode layer, where k ∈ [1, n - 1]; Before generating the (k + 1)-th electrode layer on the k-th piezoelectric layer, first set a second mask on the first mask, and the size of the second mask is larger than the size of the first mask and smaller than the size of the k-th piezoelectric layer; then generate the (k + 1)-th electrode layer on the k-th piezoelectric layer; The preparation method further includes: When k + 1 < n, before generating the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, first remove the second mask and keep the first mask; generate the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, and the area after removing the second mask and the (k + 1)-th piezoelectric layer are simultaneously sputtered and grown into one body; then remove the first mask, and generate the (k + 2)-th electrode layer on the (k + 1)-th piezoelectric layer, and the area after removing the first mask and the (k + 2)-th electrode layer are simultaneously sputtered and grown into one body; When k + 1 = n, before generating the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, first remove the second mask and keep the first mask, and set a third mask on the inner side of the edge of the (k + 1)-th electrode layer, and the third mask is annular; then generate the (k + 1)-th piezoelectric layer on the (k + 1)-th electrode layer, the (k + 1)-th piezoelectric layer is located between the first mask and the third mask, and the area after removing the second mask and the (k + 1)-th piezoelectric layer are simultaneously sputtered and grown into one body; then remove the first mask and keep the third mask, generate the (k + 2)-th electrode layer on the (k + 1)-th piezoelectric layer, and the area after removing the first mask and the (k + 2)-th electrode layer are simultaneously sputtered and grown into one body, and finally remove the third mask; The area where the third mask is located is used to form a stepped structure. In the test state, the test equipment applies a voltage to the thin film sensor through the stepped structure.

2. The multi-layer internally connected piezoelectric thin film sensor according to claim 1, wherein The number of the bridging portions is n - 1.

3. A multi-layer internally connected piezoelectric thin film sensor according to claim 1, characterized in that, When n = 2, the thin film sensor includes one bridging portion, and the center of the bridging portion coincides with the centers of the first piezoelectric layer and the second piezoelectric layer.

4. A multi-layer internally connected piezoelectric thin film sensor according to claim 1, characterized in that, When n > 2, two piezoelectric layers arranged in parallel form a piezoelectric layer group, and two bridging portions corresponding to two adjacent piezoelectric layer groups are arranged in a staggered manner.

5. A multi-layer internally connected piezoelectric thin film sensor according to claim 1, characterized in that, The bridging portion and the electrode layer are made of the same material.

6. A multi-layer internally connected piezoelectric thin film sensor according to claim 1, characterized in that, An insulating layer is provided in the insulating region, and the insulating layer has the same material as the piezoelectric layer.

7. A multi-layer internally connected piezoelectric thin film sensor according to any one of claims 1-6, characterized in that, A stepped structure is formed between the nth piezoelectric layer and the nth electrode layer.

8. The multi-layer internally connected piezoelectric film sensor according to claim 7, characterized in that, The stepped structure is a misaligned region formed between the nth piezoelectric layer and the nth electrode layer, and the outer edge of the nth electrode layer extends beyond the outer edge of the (n + 1)th electrode layer.

9. A preparation method of a multi-layer internally connected piezoelectric thin film sensor, characterized in that, The preparation method is used to prepare the multi-layer interconnected piezoelectric thin film sensor according to any one of claims 1-8. The preparation method includes: generating electrode layers and piezoelectric layers layer by layer on the bottom surface of the device substrate, and the piezoelectric layers are located between the electrode layers; the preparation method further includes: Before generating the kth piezoelectric layer on the kth electrode layer, first set a first mask on the kth electrode layer. The size of the first mask is smaller than the size of the kth electrode layer; then generate the kth piezoelectric layer on the kth electrode layer, where k ∈ [1, n - 1]; Before generating the (k + 1)th electrode layer on the kth piezoelectric layer, first set a second mask on the first mask. The size of the second mask is larger than the size of the first mask and smaller than the size of the kth piezoelectric layer; then generate the (k + 1)th electrode layer on the kth piezoelectric layer; The preparation method further includes: When k + 1 < n, before generating the (k + 1)th piezoelectric layer on the (k + 1)th electrode layer, first remove the second mask and keep the first mask; generate the (k + 1)th piezoelectric layer on the (k + 1)th electrode layer, and the region after removing the second mask and the (k + 1)th piezoelectric layer are simultaneously sputter-grown to form an integral body; then remove the first mask and generate the (k + 2)th electrode layer on the (k + 1)th piezoelectric layer, and the region after removing the first mask and the (k + 2)th electrode layer are simultaneously sputter-grown to form an integral body; When k + 1 = n, before generating the (k + 1)th piezoelectric layer on the (k + 1)th electrode layer, first remove the second mask and keep the first mask. Set a third mask inside the edge of the (k + 1)th electrode layer. The third mask is annular; then generate the (k + 1)th piezoelectric layer on the (k + 1)th electrode layer. The (k + 1)th piezoelectric layer is located between the first mask and the third mask, and the region after removing the second mask and the (k + 1)th piezoelectric layer are simultaneously sputter-grown to form an integral body; then remove the first mask and keep the third mask. Generate the (k + 2)th electrode layer on the (k + 1)th piezoelectric layer, and the region after removing the first mask and the (k + 2)th electrode layer are simultaneously sputter-grown to form an integral body, and finally remove the third mask.

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