Piezoelectric cantilever beam type sensor and preparation method thereof

Abstract

The invention discloses a piezoelectric cantilever beam type sensor and a preparation method thereof. The piezoelectric cantilever beam type sensor comprises a substrate and at least two cantilever beams located on one side of the substrate. A slit exists between two adjacent cantilever beams; the cantilever beam comprises a piezoelectric driving layer and an elastic supporting layer which are laminated; the slit penetrates through the piezoelectric driving layer and the elastic supporting layer; the piezoelectric driving layer comprises a first electrode layer, a piezoelectric layer and a second electrode layer which are arranged in a laminated mode, the first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side, away from the substrate, of the first electrode layer, and the second electrode layer is located on the side, away from the first electrode layer, of the piezoelectric layer; when the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever beam is bent, and the bent neutral surface of the cantilever beam is located between the piezoelectric layer and the elastic supporting layer. The performance of the piezoelectric layer can be ensured under the condition of low cost, and the resonant frequency of the piezoelectric cantilever beam type sensor can be easily adjusted by adjusting the thickness of the elastic supporting layer.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a piezoelectric cantilever beam sensor and a preparation method thereof. Background Art

[0002] Piezoelectric cantilever beam sensors are widely used in various sensor fields, such as microphones, speakers, accelerometers, flow sensors, etc. due to their high sensitivity and wide applicable environment. Currently, the cantilever beam structure with a piezoelectric sandwich structure plus an elastic support layer is the most widely used. The cantilever beam of this structure can be driven by a unipolar voltage. To ensure that the cantilever beam can be driven by a unipolar voltage while ensuring the driving efficiency, it is necessary to set the neutral plane of the cantilever beam outside the piezoelectric layer in the piezoelectric driving layer.

[0003] The prior art usually ensures that the bending neutral plane of the cantilever beam is outside the piezoelectric layer by setting an elastic support layer between the piezoelectric driving layer and the substrate. At the same time, since the thickness of the piezoelectric layer is usually only a few micrometers, the setting of the above elastic support layer can also enable the piezoelectric cantilever beam sensor to obtain a wider resonant frequency range.

[0004] In one prior art, a piezoelectric cantilever beam sensor can be directly obtained by preparing a piezoelectric driving layer on an SOI substrate. This is because the SOI substrate is composed of a relatively thin elastic support layer (single crystal silicon), a relatively thin insulating layer, and a relatively thick silicon substrate, and the elastic support layer of the SOI substrate has good quality and can grow a high-quality piezoelectric layer above the elastic support layer. However, due to the high price of the SOI substrate, the cost of obtaining a piezoelectric cantilever beam sensor by preparing a piezoelectric driving layer on the SOI substrate is very high, and the elastic support layer is located between the silicon substrate and the piezoelectric driving layer. After the piezoelectric cantilever beam sensor is prepared, it is not easy to adjust the resonant frequency range of the piezoelectric cantilever beam sensor by adjusting the thickness of the elastic support layer.

[0005] In another prior art, a relatively thick polysilicon layer can be grown on a common silicon substrate first as the elastic support layer, and finally a piezoelectric driving layer is prepared on the elastic support layer to obtain a piezoelectric cantilever beam sensor. Although this method has a lower cost compared to the method of directly obtaining a piezoelectric cantilever beam sensor by preparing a piezoelectric driving layer on an SOI substrate, due to the large stress of polysilicon and the poor quality of the piezoelectric layer grown on the relatively thick polysilicon, the overall performance of the finally generated piezoelectric cantilever beam sensor is poor, not as good as the performance of the piezoelectric cantilever beam sensor directly obtained by preparing a piezoelectric driving layer on an SOI substrate. Moreover, the elastic support layer in this method is also located between the silicon substrate and the piezoelectric driving layer. After the piezoelectric cantilever beam sensor is prepared, it is also not easy to adjust the resonant frequency range of the piezoelectric cantilever beam sensor by adjusting the thickness of the elastic support layer. Summary of the Invention

[0006] The present invention provides a piezoelectric cantilever sensor and a preparation method thereof, so as to solve the problems of high cost, inability to guarantee the performance of the piezoelectric layer, and difficulty in adjusting the resonance frequency range existing in the existing piezoelectric cantilever sensors.

[0007] In a first aspect, an embodiment of the present invention provides a piezoelectric cantilever sensor, including:

[0008] A substrate;

[0009] At least two cantilevers, located on one side of the substrate, with a slit between two adjacent cantilevers;

[0010] The cantilever includes a piezoelectric driving layer and an elastic support layer stacked, the piezoelectric driving layer is located on one side of the substrate, and the elastic support layer is located on the side of the piezoelectric driving layer away from the substrate; the slit penetrates through the piezoelectric driving layer and the elastic support layer;

[0011] The piezoelectric driving layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer stacked, the first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side of the first electrode layer away from the substrate, and the second electrode layer is located on the side of the piezoelectric layer away from the first electrode layer;

[0012] When the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever bends, and the bending neutral plane of the cantilever is located between the piezoelectric layer and the elastic support layer.

[0013] Optionally, the first electrode layer or the second electrode layer is grounded.

[0014] Optionally, the deflection of the cantilever is greater than the deflection of the piezoelectric driving layer.

[0015] Optionally, the distance y between the bending neutral plane and the surface of the cantilever close to the substrate side neutral Satisfies the following corresponding relationship:

[0016]

[0017] Where n≥4, and n is an integer, yi is the distance between the center of the i-th film layer and the surface of the cantilever close to the substrate side, Ei is the Young's modulus of the i-th film layer, hi is the thickness of the i-th film layer, vi is the Poisson's ratio of the i-th film layer, and the n film layers at least include the first electrode layer, the piezoelectric layer, the second electrode layer, and the elastic support layer.

[0018] Optionally, the piezoelectric cantilever beam sensor further includes a cavity penetrating the substrate;

[0019] Along the thickness direction of the substrate, the cavity at least partially overlaps with the cantilever beam.

[0020] Optionally, the piezoelectric cantilever beam sensor further includes an insulating layer;

[0021] The insulating layer is located between the substrate and the piezoelectric driving layer.

[0022] Optionally, the material of the elastic support layer includes silicon nitride or aluminum oxide.

[0023] In a second aspect, an embodiment of the present invention provides a method for manufacturing a piezoelectric cantilever beam sensor for manufacturing the piezoelectric cantilever beam sensor as described in the first aspect. The manufacturing method includes:

[0024] Prepare a substrate;

[0025] Prepare a piezoelectric driving layer on one side of the substrate. Among them, the piezoelectric driving layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in a stacked manner. The first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side of the first electrode layer away from the substrate, and the second electrode layer is located on the side of the piezoelectric layer away from the first electrode layer;

[0026] Prepare an elastic support layer on the side of the piezoelectric driving layer away from the substrate;

[0027] Prepare slits penetrating the elastic support layer and the piezoelectric driving layer to obtain at least two cantilever beams. Among them, when the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever beam bends, and the bending neutral plane of the cantilever beam is located between the piezoelectric layer and the elastic support layer.

[0028] Optionally, the piezoelectric cantilever beam sensor further includes a cavity;

[0029] After preparing the slits penetrating the elastic support layer and the piezoelectric driving layer, the manufacturing method further includes:

[0030] Prepare a cavity penetrating the substrate from the side of the substrate away from the cantilever beam, where the cavity at least partially overlaps with the cantilever beam.

[0031] Optionally, the piezoelectric cantilever beam sensor further includes a cavity;

[0032] After preparing the substrate, the manufacturing method further includes:

[0033] Prepare a sacrificial layer penetrating part of the substrate;

[0034] Prepare a piezoelectric driving layer on one side of the substrate, including:

[0035] Prepare a piezoelectric driving layer on one side of the substrate and the sacrificial layer;

[0036] After preparing a slit penetrating the elastic support layer and the piezoelectric driving layer, the preparation method further includes:

[0037] Prepare a first cavity penetrating at least part of the substrate from the side of the substrate away from the cantilever beam;

[0038] Release the sacrificial layer to obtain a second cavity, where the cavity includes the first cavity and the second cavity, and the second cavity at least partially overlaps with the cantilever beam.

[0039] In the technical solution of the embodiment of the present invention, by arranging the elastic support layer on the side of the piezoelectric driving layer away from the substrate, it can not only ensure the performance of the piezoelectric layer at low cost (i.e., without using an SOI substrate), but also easily adjust the resonance frequency of the piezoelectric cantilever sensor by adjusting the thickness of the elastic support layer.

[0040] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a schematic structural diagram of a piezoelectric cantilever sensor provided by an embodiment of the present invention;

[0043] Figure 2 It is a schematic structural diagram of a piezoelectric cantilever sensor provided by an embodiment of the present invention;

[0044] Figure 3 It is a flowchart of a preparation method of a piezoelectric cantilever sensor provided by an embodiment of the present invention;

[0045] Figure 4 It is a flowchart of another preparation method of a piezoelectric cantilever sensor provided by an embodiment of the present invention;

[0046] Figure 5Schematic diagram of the preparation process of a piezoelectric cantilever beam sensor provided by an embodiment of the present invention;

[0047] Figure 6 Schematic diagram of the preparation process of another piezoelectric cantilever beam sensor provided by an embodiment of the present invention;

[0048] Figure 7 Flowchart of the preparation method of yet another piezoelectric cantilever beam sensor provided by an embodiment of the present invention;

[0049] Figure 8 Schematic diagram of the preparation process of yet another piezoelectric cantilever beam sensor provided by an embodiment of the present invention. Detailed implementation manners

[0050] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0051] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices. The terms "upper", "lower", "left", "right", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to illustrate the relative positional relationship between each component or component part, and do not particularly limit the specific installation orientation of each component or component part.

[0052] Figure 1 Schematic diagram of the structure of a piezoelectric cantilever beam sensor provided by an embodiment of the present invention, refer to Figure 1, embodiments of the present invention provide a piezoelectric cantilever beam sensor, including a substrate 10 and at least two cantilever beams 20. The cantilever beams 20 are located on one side of the substrate 10. There is a slit 30 between two adjacent cantilever beams 20. The cantilever beam 20 includes a piezoelectric driving layer 21 and an elastic support layer 22 arranged in a stacked manner. The piezoelectric driving layer 21 is located on one side of the substrate 10, and the elastic support layer 22 is located on the side of the piezoelectric driving layer 21 away from the substrate 10. The slit 30 penetrates through the piezoelectric driving layer 21 and the elastic support layer 22. The piezoelectric driving layer 21 includes a first electrode layer 211, a piezoelectric layer 212, and a second electrode layer 213 arranged in a stacked manner. The first electrode layer 211 is located on one side of the substrate 10, the piezoelectric layer 212 is located on the side of the first electrode layer 211 away from the substrate 10, and the second electrode layer 213 is located on the side of the piezoelectric layer 212 away from the first electrode layer 211. When the voltage applied to the first electrode layer 211 is different from the voltage applied to the second electrode layer 213, the cantilever beam 20 bends, and the bending neutral plane 201 of the cantilever beam 20 is located between the piezoelectric layer 212 and the elastic support layer 22.

[0053] It should be noted that the bending neutral plane of the cantilever beam 20 refers to an imaginary plane inside the cantilever beam 20 that is neither stretched nor compressed when the cantilever beam 20 undergoes bending deformation. Two adjacent cantilever beams 20 refer to two cantilever beams 20 directly separated by the same slit 30.

[0054] Exemplarily, the piezoelectric layer 212 is composed of a piezoelectric material and has a piezoelectric effect. When different voltages are applied to the first electrode layer 211 and the second electrode layer 212 that are in direct contact with the piezoelectric layer 212 respectively, an electric field will be formed in the thickness direction of the piezoelectric layer 212. Under the action of this electric field, the piezoelectric layer 211 will deform. Since the first electrode layer 211, the second electrode layer 213, and the piezoelectric driving layer 21 are fixed together with the piezoelectric layer 211, they will also deform with the piezoelectric layer 211. Furthermore, the cantilever beam 20 composed of the first electrode layer 211, the piezoelectric layer 212, and the second electrode layer 213 will also deform, that is, bend.

[0055] Reference Figure 1 , the piezoelectric cantilever beam sensor further includes a cavity 40 that penetrates the substrate 10. Along the thickness direction of the substrate 10, the cavity 40 at least partially overlaps with the cantilever beam 20.

[0056] It can be understood that to ensure that the cantilever beam 20 can deform, a space for the cantilever beam 20 to deform needs to be provided. Therefore, a cavity 40 that penetrates the substrate 10 is provided on the substrate 10. The cantilever beam 20 that overlaps with the cavity 40 will bend without being restricted by the substrate 10, while the cantilever beam 20 that overlaps with the substrate 10 will not bend due to the restriction of the substrate 10.

[0057] It should be noted that the embodiments of the present invention do not limit the specific shapes and numbers of the cantilever beam 20 and the slit 30, and those skilled in the art can set them by themselves.

[0058] In the embodiments of the present invention, by disposing the elastic support layer 22 on the side of the piezoelectric drive layer 21 away from the substrate 10, not only can the performance of the piezoelectric layer 212 be ensured at low cost (i.e., without using an SOI substrate), that is, the piezoelectric layer has a piezoelectric effect and can deform when the voltages applied to the first electrode layer 211 and the second electrode layer 213 are different, thereby bending the cantilever beam 20, but also the resonant frequency of the piezoelectric cantilever beam sensor can be easily adjusted by adjusting the thickness of the elastic support layer 22.

[0059] In the piezoelectric cantilever beam sensor in the embodiments of the present invention, the bending neutral plane 201 of the cantilever beam 20 is located between the piezoelectric layer 212 and the elastic support layer 22. Therefore, the piezoelectric drive layer 21 in the embodiments of the present invention can be driven by a unipolar voltage, that is, the first electrode layer 211 or the second electrode layer 213 is grounded.

[0060] Exemplarily, when the first electrode layer 211 is grounded, the second electrode layer 213 is connected to an external voltage signal. When the second electrode layer 213 is grounded, the first electrode layer 211 is connected to an external voltage signal. It should be noted that the above external voltage signal can be an AC signal. It can be understood that when the external voltage signal is an AC signal with alternating positive and negative voltages, the cantilever beam 20 will vibrate up and down.

[0061] It should be noted that when the piezoelectric drive layer 21 in the embodiments of the present invention uses unipolar drive, the deflection of the cantilever beam 20 is greater than the deflection of the piezoelectric drive layer 21.

[0062] It should be noted that the deflection refers to the elastic deformation amount that occurs when a structure or material is subjected to an external force, and usually refers to the displacement perpendicular to the original axis or plane.

[0063] Exemplarily, from the fact that the deflection of the cantilever beam 20 is greater than the deflection of the piezoelectric drive layer 21, it can be seen that the presence of the elastic support layer enables the cantilever beam 20 to withstand greater bending deformation.

[0064] The distance y between the bending neutral plane 201 in the embodiments of the present invention and the surface of the cantilever beam 20 close to the substrate 10 neutral satisfies the following corresponding relationship:

[0065]

[0066] Wherein, n≥4 and n is an integer, yi is the distance between the center of the i-th film layer and the surface of the cantilever beam 20 close to the substrate 10, Ei is the Young's modulus of the i-th film layer, hi is the thickness of the i-th film layer, vi is the Poisson's ratio of the i-th film layer, and the n film layers at least include a first electrode layer 211, a piezoelectric layer 212, a second electrode layer 213, and an elastic support layer 22.

[0067] It should be noted that the thickness of the first electrode layer 211, the thicknesses, Poisson's ratios, Young's moduli of the piezoelectric layer 212 and the second electrode layer 213 respectively, and the distance between them and the surface of the cantilever beam 20 close to the substrate 10 are all known. The Poisson's ratio and Young's modulus of the elastic support layer 22 are known, and the thickness of the elastic support layer 22 is variable and adjustable. The distance y between the bending neutral plane 201 and the surface of the cantilever beam 20 close to the substrate 10 neutral can be set. Those skilled in the art only need to set the distance y between the bending neutral plane 201 and the surface of the cantilever beam 20 close to the substrate 10 neutral , and then the thickness of the cantilever beam 20 can be determined through the above formula. Then, during the manufacturing process of the piezoelectric cantilever beam sensor, the thickness of the cantilever beam 20 can be controlled to make the bending neutral plane 201 located at a suitable position, that is, between the piezoelectric layer 212 and the elastic support layer 22.

[0068] It should be noted that, in addition to the above-mentioned piezoelectric drive layer 21 and elastic support layer 22 arranged in a stack, the cantilever beam 20 in the embodiment of the present invention may further include other film layers. The piezoelectric layer 212 may be composed of a single film layer or multiple film layers arranged in a stack. The embodiment of the present invention does not limit the film layers included in the cantilever beam 20 and the film layers included in the piezoelectric layer. Those skilled in the art can set them by themselves, and the above formula is also applicable to the case where the cantilever beam 20 includes other film layers and the piezoelectric layer includes multiple film layers.

[0069] Figure 2 is a schematic structural diagram of a piezoelectric cantilever beam sensor provided by an embodiment of the present invention. Refer to Figure 2 , the piezoelectric cantilever beam sensor further includes an insulating layer 50. The insulating layer 50 is located between the substrate 10 and the piezoelectric drive layer 21.

[0070] Exemplarily, setting the insulating layer 50 between the substrate 10 and the piezoelectric drive layer 21 can play roles of electrical isolation, protecting the piezoelectric material, and improving reliability.

[0071] It should be noted that the insulating layer 50 in the embodiment of the present invention can be Figure 2is only located between the substrate 10 and the piezoelectric driving layer 21; it may also be located between the substrate 10 and the piezoelectric driving layer 21 and between the cavity 40 and the piezoelectric driving layer 21. In this case, the cantilever beam 20 in the embodiment of the present invention should include an insulating layer 50, and the slit 30 will also penetrate through the insulating layer 50 and communicate with the cavity 40.

[0072] As a feasible implementation manner, the material of the elastic support layer 22 in the embodiment of the present invention includes silicon nitride or aluminum oxide.

[0073] The embodiment of the present invention provides a preparation method of a piezoelectric cantilever beam type sensor for preparing the piezoelectric cantilever beam type sensor described in any one of the above embodiments of the present invention. Figure 3 is a flowchart of a preparation method of a piezoelectric cantilever beam type sensor provided by an embodiment of the present invention. Refer to Figure 3 , the preparation method of the piezoelectric cantilever beam type sensor in the embodiment of the present invention includes:

[0074] S110. Prepare a substrate.

[0075] Exemplarily, refer to Figure 1 and Figure 2 , a silicon substrate with a specific crystal phase can be directly grown on the substrate.

[0076] Refer to Figure 2 , the piezoelectric cantilever beam type sensor in the embodiment of the present invention may further include an insulating layer 50, and the material of the insulating layer 50 may be silicon dioxide. Therefore, after preparing the silicon substrate, the preparation method in the embodiment of the present invention may further include: oxidizing one side of the silicon substrate to obtain an insulating layer 50 composed of silicon dioxide. It can be understood that, to ensure the flatness of the subsequent prepared piezoelectric driving layer 21, the insulating layer 50 can also be subjected to a planarization process, specifically, a chemical mechanical polishing (CMP) process can be used.

[0077] S120. Prepare a piezoelectric driving layer on one side of the substrate, wherein the piezoelectric driving layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in a stacked manner. The first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side of the first electrode layer away from the substrate, and the second electrode layer is located on the side of the piezoelectric layer away from the first electrode layer.

[0078] Exemplarily, refer to Figure 1 and Figure 2 , the first electrode layer 211, the piezoelectric layer 212, and the second electrode layer 213 can be sequentially prepared on one side of the substrate 10 or on the side of the insulating layer 50 away from the substrate 10 by a deposition or evaporation process.

[0079] S130. Prepare an elastic support layer on the side of the piezoelectric driving layer away from the substrate.

[0080] Exemplarily, referring to Figure 1 and Figure 2 , an elastic support layer 22 can be prepared on the side of the piezoelectric driving layer 21 away from the substrate 10 by means of deposition or evaporation. It can be understood that, to ensure the flatness of the surface of the finally prepared piezoelectric cantilever beam sensor, the elastic support layer 22 can also be subjected to a planarization process. Specifically, a chemical mechanical polishing (CMP) process can be adopted.

[0081] S140. Prepare slits penetrating the elastic support layer and the piezoelectric driving layer to obtain at least two cantilever beams. Among them, when the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever beam bends, and the bending neutral plane of the cantilever beam is located between the piezoelectric layer and the elastic support layer.

[0082] Exemplarily, referring to Figure 1 and Figure 2 , slits 30 penetrating the elastic support layer 22 and the piezoelectric driving layer 21 can be etched on the side of the elastic support layer 22 away from the substrate through an etching process.

[0083] In the embodiment of the present invention, by preparing the elastic support layer 22 on the side of the piezoelectric driving layer 21 away from the substrate 10, not only can the performance of the piezoelectric layer 212 be ensured at low cost (i.e., without using an SOI substrate), that is, the piezoelectric layer has a piezoelectric effect and can deform when the voltage applied to the first electrode layer 211 is different from the voltage applied to the second electrode layer 213, thereby causing the cantilever beam 20 to bend, but also the resonant frequency of the piezoelectric cantilever beam sensor can be easily adjusted by adjusting the thickness of the elastic support layer 22.

[0084] Referring to Figure 1 and Figure 2 , it should be noted that, to ensure that the cantilever beam 20 in the embodiment of the present invention has a space for bending vibration, the piezoelectric cantilever beam sensor in the embodiment of the present invention should also include a cavity 40 penetrating the substrate 10 and at least partially overlapping with the cantilever beam 20. Figure 4 is a flowchart of another method for manufacturing a piezoelectric cantilever beam sensor provided by an embodiment of the present invention. Figure 4 The shown embodiment enriches the process of the method for manufacturing a piezoelectric cantilever beam sensor on the basis of the above embodiment and details how to prepare the cavity. Referring to Figure 4 , the method for manufacturing a piezoelectric cantilever beam sensor in the embodiment of the present invention includes:

[0085] S210. Prepare a substrate.

[0086] Exemplarily, Figure 5 is a schematic diagram of a manufacturing process of a piezoelectric cantilever beam sensor provided by an embodiment of the present invention. Figure 6Schematic diagram of the preparation process of another piezoelectric cantilever beam sensor provided by an embodiment of the present invention. The prepared substrate 10 is as shown in Figure 5 Figure (a1) in Figure 6 or Figure (b1) in

[0087] Figure 6 The schematic diagram of the preparation process shown also shows the process of preparing the insulating layer 50 on one side of the substrate 10. Specifically, the insulating layer 50 can be prepared on one side of the substrate 10 through a deposition or evaporation process. The prepared insulating layer 50 is as shown in Figure 6 Figure (b2) in

[0088] S220. Prepare a piezoelectric driving layer on one side of the substrate. The piezoelectric driving layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in a stacked manner. The first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side of the first electrode layer away from the substrate, and the second electrode layer is located on the side of the piezoelectric layer away from the first electrode layer.

[0089] Exemplarily, the prepared substrate piezoelectric driving layer 21 is as shown in Figure 5 Figure (a2) in Figure 6 or Figure (b3) in Figure 5 The piezoelectric driving layer 21 in Figure 6 is prepared on one side of the substrate 10, and the piezoelectric driving layer 21 in

[0090] is prepared on the side of the insulating layer 50 away from the substrate 10.

[0091] S230. Prepare an elastic support layer on the side of the piezoelectric driving layer away from the substrate. Figure 5 Exemplarily, the prepared elastic support layer 22 is as shown in Figure 6 Figure (a3) in

[0092] or Figure (b4) in

[0093] S240. Prepare slits penetrating through the elastic support layer and the piezoelectric driving layer to obtain at least two cantilever beams. When the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever beams bend, and the bending neutral plane of the cantilever beams is located between the piezoelectric layer and the elastic support layer. Figure 5 Exemplarily, the prepared slit 30 is as shown in Figure 6 Figure (a4) in

[0094] or Figure (b5) in

[0095] Exemplarily, a cavity 40 penetrating through the substrate 10 can be prepared from the side of the substrate 10 away from the cantilever beam 20 by an etching process. The prepared cavity 40 is as shown in Figure 5 Figure (a5) in Figure 6 or Figure (b6) in Figure 5 . The difference is that the cavity 40 in Figure 6 penetrates through the substrate 10, and the cavity 40 in

[0096] in addition to penetrating through the substrate 10, also penetrates through the insulating layer 50. Figure 1 and Figure 2 It should be noted that, in order to ensure that the cantilever beam 20 in the embodiments of the present invention has a space for bending vibration, the piezoelectric cantilever beam type sensor in the embodiments of the present invention should also include a cavity 40 that penetrates through the substrate 10 and at least partially overlaps with the cantilever beam 20. Figure 7 is a flowchart of another preparation method of the piezoelectric cantilever beam type sensor provided by the embodiments of the present invention. The embodiment shown in Figure 7 enriches the process of the preparation method of the piezoelectric cantilever beam type sensor on the basis of the above embodiments, and details how to prepare the cavity. Referring to Figure 5 , the preparation method of the piezoelectric cantilever beam type sensor in the embodiments of the present invention includes:

[0097] S310. Prepare a substrate.

[0098] Figure 8 is a schematic diagram of another preparation process of the piezoelectric cantilever beam type sensor provided by the embodiments of the present invention. The prepared substrate 10 is as shown in Figure 8 Figure (c1) in

[0099] S320. Prepare a sacrificial layer that penetrates through part of the substrate.

[0100] Exemplarily, a groove penetrating through part of the substrate 10 can be first prepared from one side of the substrate 10 by an etching process, and then a sacrificial layer 60 that penetrates through part of the substrate 10 can be obtained by filling the groove with a silicon dioxide material through a deposition process. The prepared sacrificial layer 60 is as shown in Figure 8 Figure (c2) in

[0101] S330. Prepare a piezoelectric driving layer on one side of the substrate and the sacrificial layer. Among them, the piezoelectric driving layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer stacked. The first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side of the first electrode layer away from the substrate, and the second electrode layer is located on the side of the piezoelectric layer away from the first electrode layer.

[0102] Exemplarily, the prepared piezoelectric driving layer 21 is as shown in Figure 8 Figure (c3) therein.

[0103] S340. Prepare an elastic support layer on the side of the piezoelectric driving layer away from the substrate.

[0104] Exemplarily, the prepared elastic support layer 22 is as shown in Figure 8 Figure (c4) therein.

[0105] S350. Prepare slits penetrating through the elastic support layer and the piezoelectric driving layer to obtain at least two cantilever beams. Among them, when the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever beams bend, and the bending neutral plane of the cantilever beams is located between the piezoelectric layer and the elastic support layer.

[0106] Exemplarily, the prepared slit 30 is as shown in Figure 8 Figure (c5) therein.

[0107] S360. Prepare a first cavity penetrating at least part of the substrate from the side of the substrate away from the cantilever beam.

[0108] Exemplarily, a first cavity 41 penetrating at least part of the substrate 10 can be prepared from the side of the substrate 10 away from the cantilever beam 20 through an etching process. The prepared first cavity 41 is as shown in Figure 8 Figure (c6) therein. The first cavity 41 exposes at least part of the sacrificial layer 60 to ensure that the sacrificial layer 60 can be released.

[0109] S370. Release the sacrificial layer to obtain a second cavity. Among them, the cavity includes the first cavity and the second cavity, and the second cavity overlaps at least part of the cantilever beam.

[0110] Exemplarily, the sacrificial layer 60 can be removed through a wet release process to obtain a second cavity 42. The cavity 40 includes the first cavity 41 and the second cavity 42. Along the thickness direction of the substrate, the second cavity 42 overlaps at least part of the cantilever beam 20. By adopting the process of presetting the sacrificial layer 60 to prepare the cavity 40, side etching can be avoided, which is beneficial to ensuring the dimensional stability of the active area of the piezoelectric cantilever sensor (i.e., the area where the cantilever beam 20 overlaps with the second cavity 42 along the thickness direction of the substrate 10), beneficial to ensuring the stability of the resonance frequency, and further beneficial to improving the performance and accuracy of the piezoelectric cantilever sensor.

[0111] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A piezoelectric cantilever beam type sensor, characterized in that, Comprising: A substrate; At least two cantilever beams located on one side of the substrate, with a slit between two adjacent cantilever beams; The cantilever beam includes a piezoelectric driving layer and an elastic support layer arranged in a stack. The piezoelectric driving layer is located on one side of the substrate, and the elastic support layer is located on the side of the piezoelectric driving layer away from the substrate; the slit penetrates through the piezoelectric driving layer and the elastic support layer; The piezoelectric driving layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in a stack. The first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side of the first electrode layer away from the substrate, and the second electrode layer is located on the side of the piezoelectric layer away from the first electrode layer; When the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever beam bends, and the bending neutral plane of the cantilever beam is located between the piezoelectric layer and the elastic support layer.

2. The piezoelectric cantilever beam type sensor according to claim 1, wherein The first electrode layer or the second electrode layer is grounded.

3. The piezoelectric cantilever beam type sensor according to claim 2, wherein The deflection of the cantilever beam is greater than the deflection of the piezoelectric driving layer.

4. The piezoelectric cantilever beam type sensor according to claim 1, characterized in that The distance y between the bending neutral plane and the surface of the cantilever beam close to the substrate side neutral satisfies the following corresponding relationship: Where n≥4 and n is an integer, yi is the distance between the center of the i-th film layer and the surface of the cantilever beam close to the substrate, Ei is the Young's modulus of the i-th film layer, hi is the thickness of the i-th film layer, vi is the Poisson's ratio of the i-th film layer, and the n film layers at least include the first electrode layer, the piezoelectric layer, the second electrode layer, and the elastic support layer.

5. The piezoelectric cantilever beam type sensor according to claim 1, characterized in that, The piezoelectric cantilever beam sensor further includes a cavity penetrating through the substrate; Along the thickness direction of the substrate, the cavity at least partially overlaps with the cantilever beam.

6. The piezoelectric cantilever beam type sensor according to claim 1, characterized in that, The piezoelectric cantilever beam sensor further includes an insulating layer; The insulating layer is located between the substrate and the piezoelectric driving layer.

7. The piezoelectric cantilever beam type sensor according to claim 1, characterized in that, The material of the elastic support layer includes silicon nitride or aluminum oxide.

8. A preparation method of a piezoelectric cantilever beam type sensor for manufacturing the piezoelectric cantilever beam type sensor according to any one of claims 1-7, characterized in that, The preparation method includes: Preparing a substrate; Preparing a piezoelectric driving layer on one side of the substrate, where the piezoelectric driving layer includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in a stack. The first electrode layer is located on one side of the substrate, the piezoelectric layer is located on the side of the first electrode layer away from the substrate, and the second electrode layer is located on the side of the piezoelectric layer away from the first electrode layer; Preparing an elastic support layer on the side of the piezoelectric driving layer away from the substrate; Preparing a slit penetrating through the elastic support layer and the piezoelectric driving layer to obtain at least two cantilever beams, where when the voltage applied to the first electrode layer is different from the voltage applied to the second electrode layer, the cantilever beam bends, and the bending neutral plane of the cantilever beam is located between the piezoelectric layer and the elastic support layer.

9. The preparation method according to claim 8, wherein, The piezoelectric cantilever beam sensor further includes a cavity; After preparing the slit penetrating through the elastic support layer and the piezoelectric driving layer, the preparation method further includes: Preparing a cavity penetrating through the substrate from the side of the substrate away from the cantilever beam, where the cavity at least partially overlaps with the cantilever beam.

10. The preparation method according to claim 8, characterized in that, The piezoelectric cantilever beam sensor further includes a cavity; After preparing the substrate, the preparation method further includes: Preparing a sacrificial layer penetrating through part of the substrate; Preparing a piezoelectric driving layer on one side of the substrate, including: Fabricate a piezoelectric driving layer on one side of the substrate and the sacrificial layer; After fabricating a slit that penetrates the elastic support layer and the piezoelectric driving layer, the fabrication method further includes: Fabricate a first cavity that penetrates at least part of the substrate from a side of the substrate away from the cantilever beam; Release the sacrificial layer to obtain a second cavity, wherein the cavity includes the first cavity and the second cavity, and the second cavity at least partially overlaps with the cantilever beam.

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