WO2021253444A1

WO2021253444A1 - Ultrasonic transducer preparation method, ultrasonic transducer and information acquisition element

Info

Publication number: WO2021253444A1
Application number: PCT/CN2020/097251
Authority: WO
Inventors: 王文轩; 沈健; 陆斌
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2020-06-19
Filing date: 2020-06-19
Publication date: 2021-12-23

Abstract

Provided are an ultrasonic transducer preparation method, an ultrasonic transducer and an information acquisition element. The method comprises: forming a first electrode on a substrate layer; forming a passivation protection layer on a first surface of the first electrode; forming a circuit layer on a first surface of the passivation protection layer; removing the substrate layer; forming a piezoelectric layer on a second surface of the first electrode; and forming a second electrode on a first surface of the piezoelectric layer. Due to the fact that the substrate layer is removed, the thickness of the ultrasonic transducer is small, and the ultrasonic transducer can be suitable for a scenario where an ultrathin ultrasonic transducer is needed. An effective device structure layer through which ultrasonic signals generated by the ultrasonic transducer pass during propagation does not comprise a substrate layer, such that energy loss caused by the ultrasonic signals penetrating the substrate layer is prevented, and the ultrasonic performance of the ultrasonic transducer is better.

Description

Ultrasonic transducer preparation method, ultrasonic transducer and information acquisition element

Technical field

The embodiments of the present application relate to the field of electronic information technology, in particular to a method for preparing an ultrasonic transducer, an ultrasonic transducer, and an information acquisition element.

Background technique

An ultrasonic transducer is a device that can convert sound energy and electrical energy. The piezoelectric material in the ultrasonic transducer can generate a voltage difference between the two ends when deformed. When there is a voltage difference between the two ends, the piezoelectric material can generate deformation. Using this characteristic of piezoelectric materials can realize the mutual conversion of mechanical vibration and alternating current. An ultrasonic transducer usually includes a substrate, a circuit layer (circuit) prepared on the substrate layer, a piezoelectric layer prepared on the circuit layer, and an electrode layer (electrode), where the piezoelectric layer is composed of piezoelectric materials.

Among the above-mentioned ultrasonic transducers, since the base layer is not easy to bend, the ultrasonic transducer cannot be applied to flexible screens or other scenes that require flexible ultrasonic transducers. In addition, the thickness of the base layer results in ultrasonic transducers. The size of the device is large, and it is easy to take up more space in mobile phones or other terminal products. In the process of generating ultrasonic signals from the ultrasonic transducer, the ultrasonic signal generated by the piezoelectric layer penetrates the base layer when propagating, and the energy loss caused by the ultrasonic signal penetrating the base layer is large, which leads to the ultrasonic wave of the ultrasonic transducer. Performance is poor.

Summary of the invention

In view of this, the embodiments of the present invention provide a method for manufacturing an ultrasonic transducer, an ultrasonic transducer, and an information acquisition element to overcome the defects in the prior art.

In the first aspect, an embodiment of the present application provides a method for manufacturing an ultrasonic transducer, including:

A first electrode is formed on the base layer; a passivation protection layer is formed on the first surface of the first electrode, the first surface of the first electrode is on the side of the first electrode away from the base layer; on the first surface of the passivation protection layer A circuit layer is formed, the first surface of the passivation protection layer is on the side of the passivation protection layer away from the first electrode; the base layer is removed; the piezoelectric layer is formed on the second surface of the first electrode, and the second surface of the first electrode is on the The first electrode is away from the side of the passivation protection layer; the second electrode is formed on the first surface of the piezoelectric layer, and the first surface of the piezoelectric layer is on the side of the piezoelectric layer away from the first electrode.

In the second aspect, an embodiment of the present application provides an ultrasonic transducer, including: a functional layer, a circuit layer, a piezoelectric layer, a passivation protection layer, a first electrode, and a second electrode;

The functional layer is a flexible dielectric; the circuit layer is arranged between the functional layer and the passivation protection layer; the first electrode is arranged on the side of the passivation protection layer away from the circuit layer; the piezoelectric layer is arranged on the first electrode away from the passivation protection layer One side, and the piezoelectric layer is located between the first electrode and the second electrode.

In a third aspect, an embodiment of the present application provides an information acquisition element. The information acquisition element includes an ultrasonic transducer array, and the ultrasonic transducer array is an array composed of at least two ultrasonic transducers as described in the second aspect.

In the method for manufacturing the ultrasonic transducer, the ultrasonic transducer, and the information acquisition element provided by the embodiments of the application, a first electrode is formed on a base layer; a passivation protection layer is formed on the first surface of the first electrode; and a passivation protection layer is formed on the first surface of the first electrode. A circuit layer is formed on the first surface; the base layer is removed; the piezoelectric layer is formed on the second surface of the first electrode; the second electrode is formed on the first surface of the piezoelectric layer. Because of the removal of the base layer, the thickness of the ultrasonic transducer is small, which can be applied to scenes that require ultra-thin ultrasonic transducers. Moreover, the effective device structure layer through which the ultrasonic signal generated by the ultrasonic transducer propagates does not include the base layer, which prevents energy loss due to the penetration of the ultrasonic signal through the base layer, and makes the ultrasonic performance of the ultrasonic transducer better.

Description of the drawings

Hereinafter, some specific embodiments of the embodiments of the present application will be described in detail in an exemplary but not restrictive manner with reference to the accompanying drawings. The same reference numerals in the drawings indicate the same or similar components or parts. Those skilled in the art should understand that these drawings are not necessarily drawn in ratios. In the attached picture:

Fig. 1 is a schematic structural diagram of an ultrasonic transducer provided by related technologies;

Figure 2 is a schematic structural diagram of an ultrasonic transducer provided by related technologies;

Fig. 3 is a schematic structural diagram of an ultrasonic transducer provided by related technologies;

4 is a flowchart of a method for manufacturing an ultrasonic transducer provided by an embodiment of the application;

Fig. 5 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application;

Fig. 6 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application;

Fig. 7 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application;

FIG. 8 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application; FIG.

FIG. 9 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application; FIG.

FIG. 10 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application; FIG.

Fig. 11 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application;

FIG. 12 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application; FIG.

FIG. 13 is a schematic structural diagram of an ultrasonic transducer in a preparation process provided by an embodiment of the application; FIG.

FIG. 14 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application;

15 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application;

FIG. 16 is a flowchart of a method for manufacturing an ultrasonic transducer according to an embodiment of the application;

FIG. 17 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application;

FIG. 18 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application;

FIG. 19 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application;

20 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application;

FIG. 21 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application;

FIG. 22 is a schematic structural diagram of an information collection element provided by an embodiment of this application;

FIG. 23 is a schematic structural diagram of an information collection element provided by an embodiment of the application.

detailed description

Ultrasonic transducers are devices that can mutually convert sound energy and electrical energy. As shown in FIG. 1, the ultrasonic transducer 100 includes a base layer 101, a circuit layer 102 prepared on the base layer 101, a piezoelectric layer 103 prepared on the circuit layer 102, and an electrode layer 104, wherein the piezoelectric layer 103 is formed by pressing Constructed of electrical materials.

In the above-mentioned ultrasonic transducer, since the base layer is not easy to bend, the ultrasonic transducer cannot be applied to a flexible screen or other scenes that require a flexible ultrasonic transducer. In addition, because the circuit layer is prepared directly on the base layer, Therefore, the base layer is difficult to be very thin, and its thickness is large, resulting in a large thickness of the ultrasonic transducer, which easily takes up more space in mobile phones or other terminal products.

When the piezoelectric layer 103 in the ultrasonic transducer 100 generates ultrasonic waves, the propagation direction of the ultrasonic signals is bidirectional, that is, the ultrasonic signals propagate in two directions toward the base layer 101 and away from the base layer 101 respectively. When the matching layer 105 is located below the base layer 101, as shown in FIG. In this process, the ultrasonic signal 1031 penetrates the base layer 101 and causes more energy loss, which makes the ultrasonic performance of the ultrasonic transducer poor. When the matching layer 105 is located above the electrode layer 104, as shown in FIG. 3, the ultrasonic signal 1032 propagating in the direction away from the base layer 101 enters the matching layer 105 through the electrode layer 104, and the ultrasonic signal 1033 propagating in the direction toward the base layer 101 penetrates After the circuit layer 102 and the base layer 101, reflection occurs between the base layer 101 and the reflective layer 106, and the reflected ultrasonic signal 1033 sequentially passes through the base layer 101, the circuit layer 102, the piezoelectric layer 103 and the electrode layer 104 and enters the matching layer 105. Among them, the ultrasonic signal 1033 propagating in the direction toward the base layer 101 passes through the base layer 101 twice before entering the matching layer 105, causing more energy loss, and the ultrasonic performance of the ultrasonic transducer is poor.

In another type of ultrasonic transducer, the opening structure is arranged in the base layer to reduce the thickness of part of the base layer to reduce the energy loss caused by the ultrasonic signal penetrating the base layer. However, in this ultrasonic transducer, because there is a circuit layer above the base layer, it is difficult to directly set the opening structure in the base layer, resulting in higher difficulty in setting the opening structure; secondly, even if a part of the opening is provided in the base layer Structure, the open-hole structure cannot directly contact the circuit layer carried by the base layer, that is, the open-hole structure can only be a blind hole. The current uniformity and thickness accuracy of the blind hole technology are difficult to control, which also leads to the arrangement of the open-hole structure The difficulty is relatively high; in addition, even if a part of the opening structure is provided in the base layer, only a part of the thickness of the base layer can be reduced.

The preparation method of the ultrasonic transducer, the ultrasonic transducer, and the information collection element provided in the embodiments of the present application can overcome the above-mentioned defects. The specific implementation of the embodiments of the present invention will be further described below in conjunction with the accompanying drawings of the embodiments of the present invention.

Example one

Embodiment 1 of the present application provides a method for manufacturing an ultrasonic transducer, as shown in FIG. 4, which is a flowchart of a method for manufacturing an ultrasonic transducer provided by an embodiment of the present application. The preparation method of the ultrasonic transducer includes the following steps:

201. A first electrode is formed on the base layer.

It should be noted that the first electrode layer may be formed on the base layer first, and then the first electrode layer may be imaged to form the first electrode. Of course, this is only an exemplary description, which does not mean that the application is limited to this. The material of the base layer may be a dielectric, and the material of the first electrode is a conductive material. Optionally, the material constituting the first electrode may include metals and oxides, where the metals include simple metals such as aluminum, copper, gold, molybdenum, platinum, palladium, and alloys, etc., and the oxides include indium tin oxide (ITO), etc. The embodiment of the present application does not specifically limit the material constituting the first electrode, and the material constituting the first electrode can be set by a person skilled in the art according to the selected process platform. As shown in FIG. 5, a first electrode 302 is formed on the base layer 301.

202. Form a passivation protection layer on the first surface of the first electrode.

The first surface of the first electrode is on the side of the first electrode away from the base layer. The second surface of the first electrode may be on the side close to the base layer. Optionally, the material constituting the passivation protection layer includes organic passivation and inorganic passivation. Illustratively, the material constituting the passivation protection layer is silicon oxide or silicon nitride. The materials are not specifically limited. As shown in FIG. 6, a passivation protection layer 303 is formed on the first surface of the first electrode 302.

203. Form a circuit layer on the first surface of the passivation protection layer.

The first surface of the passivation protection layer is on the side of the passivation protection layer away from the first electrode. The second surface of the passivation protection layer may be on the side close to the first electrode. Optionally, the circuit layer may be a complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, CMOS) circuit layer, or a thin film transistor (Thin Film Transistor, TFT) circuit layer. The circuit layer may include the control circuit of the ultrasonic transducer prepared by the method for preparing the ultrasonic transducer provided in the embodiment of the present application. Of course, this is only an exemplary description, which does not mean that the application is limited to this. As shown in FIG. 7, a circuit layer 304 is formed on the first surface of the passivation protection layer 303. A circuit layer is provided on the first surface of the passivation protection layer, the side of the second surface of the passivation protection layer is the first electrode, and the first electrode and the circuit layer are separated by the passivation protection layer to avoid mutual influence.

It should be noted that, after the circuit layer is formed, a matching layer or a functional layer can also be formed on the circuit layer. Here, four specific application scenarios are listed for description. Of course, this is only an exemplary description and does not represent This application is limited to this.

Optionally, in the first application scenario, after the circuit layer is formed on the first surface of the passivation protection layer, the method further includes: forming a matching layer on the first surface of the circuit layer, and the first surface of the circuit layer is on the circuit layer. On the side away from the passivation protection layer, the matching layer includes an acoustic impedance matching material for reducing signal energy loss. As shown in FIG. 8, a matching layer 305 is formed on the first surface of the circuit layer 304, and a matching layer 305 for reducing signal energy loss is formed on the first surface of the circuit layer 304, which can increase the acoustic impedance of the prepared ultrasonic transducer .

Optionally, in the second application scenario, after the circuit layer is formed on the first surface of the passivation protection layer, the method further includes: forming a functional layer on the first surface of the circuit layer, and the first surface of the circuit layer is on the circuit layer. The side away from the passivation protection layer; the first opening to the circuit layer is formed on the first surface of the functional layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer; on the first surface of the functional layer The circuit layer is deposited and imaged to form an electrical connection terminal that is electrically connected to the circuit layer through the first opening, so that the circuit layer is connected to the outside through the electrical connection terminal. As shown in FIG. 9, the first surface of the circuit layer 304 forms a functional layer 306, the first surface of the functional layer 306 forms a first opening 3061 reaching the circuit layer 304, and the first surface of the functional layer 306 forms a first opening through 3061 is electrically connected to the electrical connection terminal 3062 of the circuit layer 304. In the second application scenario, the functional layer 306 can protect and support the circuit layer 304, and through the first opening 3061, the circuit layer 304 can be The electrical connection terminal is connected to the outside, making the circuit design more flexible.

Optionally, in the third application scenario, after the circuit layer is formed on the first surface of the passivation protection layer, the method further includes: forming a functional layer on the first surface of the circuit layer, and the first surface of the circuit layer is on the circuit layer. The side away from the passivation protection layer; a second opening reaching the circuit layer is formed on the first surface of the functional layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer, so that the first surface of the circuit layer , The exposed portion at the second opening forms a signal reflection surface. As shown in FIG. 10, the first surface of the circuit layer 304 forms a functional layer 306, and the first surface of the functional layer 306 forms a second opening 3063 reaching the circuit layer 304. In the third application scenario, the functional layer 306 is not only It is used to support the circuit layer 304 and to form a reflective surface. Here, the part exposed at the second opening 3063, that is, the interface between the air and the circuit layer, can form a signal reflective surface to improve signal strength. Of course, the second opening 3063 can also be filled with reflective material to improve the reflection effect.

Optionally, in the fourth application scenario, after the circuit layer is formed on the first surface of the passivation protection layer, the method further includes: forming a functional layer on the first surface of the circuit layer, and the first surface of the circuit layer is on the circuit layer. The side away from the passivation protection layer; a third opening that reaches the circuit layer is formed on the first surface of the functional layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer; for filling in the third opening Acoustic impedance matching material for reducing signal energy loss. As shown in FIG. 11, the first surface of the circuit layer 304 forms a functional layer 306, and the first surface of the functional layer 306 forms a third opening 3063 reaching the circuit layer 304. The third opening 3063 is filled with an acoustic impedance matching material 307. The fourth application scenario is similar to the first application scenario. The difference is that in the fourth application scenario, the acoustic impedance matching material is filled in the third opening 3063 of the functional layer, which can not only support the circuit layer 304, but also improve the signal strength.

It should be noted that in the above four application scenarios, in the first application scenario, a matching layer is formed on the first surface of the circuit layer to reduce signal energy loss; the second application scenario, the third application scenario, and the fourth application In the scenarios, the functional layer is formed on the first surface of the circuit layer. The processing of the functional layer is different in these three application scenarios. In the second application scenario, the first opening is formed in the functional layer so that the circuit layer passes through the first opening. Connected to the outside. In the third application scenario, a second opening is formed in the functional layer, and a reflective surface is formed at the second opening to improve signal strength. In the fourth application scenario, a third opening is formed in the functional layer, and The acoustic impedance matching material is filled to improve the signal strength. Therefore, the above four application scenarios can be combined arbitrarily or applied separately, which is not limited in this application.

204. Remove the base layer.

It should be noted that in order to facilitate the operation, it can be turned over, and then the base layer can be removed. In steps 201-203, the side of the base layer close to the circuit layer can be defined as the upper side of the base layer (that is, the side where the first surface of the base layer is located), and the side of the circuit layer close to the base layer can be defined as the circuit layer Below, the other side of the circuit layer is defined as the upper side of the circuit layer (that is, the side where the first surface of the circuit layer is located). The above and below defined here are all definitions for explaining the technology of this solution , Does not represent any limitation, and can also be defined and described in other ways. As shown in FIG. 12, after turning over and removing the base layer 301, the first electrode 302 is located above the passivation protection layer 303.

Optionally, in an implementation manner, a sacrificial layer may be provided to facilitate removal of the base layer. For example, forming a first electrode on the base layer includes: forming a sacrificial layer on the base layer and forming a sacrificial layer on the first surface of the sacrificial layer. The first electrode is formed, and the first surface of the sacrificial layer is on the side of the sacrificial layer away from the base layer; removing the base layer includes: removing the base layer and the sacrificial layer. Providing a sacrificial layer between the base layer and the first electrode makes it easier to remove the base layer.

Optionally, the material constituting the sacrificial layer includes amorphous silicon, silicon dioxide, polyimide (PI), etc., for example, the sacrificial layer includes an amorphous silicon film or a silicon dioxide film. The embodiments of the present application do not specifically limit the material constituting the sacrificial layer, and the material constituting the sacrificial layer can be set by those skilled in the art according to the process of removing the base layer. Exemplarily, when the process for removing the base layer is a laser removal process, the material constituting the sacrificial layer may be polyimide or amorphous silicon; when the process for removing the base layer is a wet etching process, the material constituting the sacrificial layer The material can be amorphous silicon or silicon dioxide, and the sacrificial layer is used as an etch stop layer.

The process of removing the sacrificial layer and the base layer can be determined according to the material constituting the base layer. Exemplarily, when the material constituting the base layer is silicon, the sacrificial layer and the base layer can be removed by using a grinding process and an etching process. Wherein, the main thickness of the base material in the base layer can be removed by a grinding process first, and then an etching process can be used for etching, and the sacrificial layer can be made of silicon oxide material as an etching stop layer. The etching process may be a dry etching process, or a wet etching process, or a dry and wet etching process.

Exemplarily, when the material constituting the base layer is glass, the sacrificial layer and the base layer can be removed by using a grinding process in conjunction with an etching process. The grinding process can be used to remove the base material of the main thickness in the base layer, and then the etching process can be used to remove the base material of the main thickness. The etching process performs etching. Compared with when the material constituting the base layer is silicon, when the material constituting the base layer is glass, the corresponding etching process is different (for example, when the material constituting the base layer is glass, the chemical composition of wet etching in the corresponding etching process is Different), the sacrificial layer can be made of silicon material (for example, amorphous silicon, etc.) as an etch stop layer.

Exemplarily, a laser lift off (Laser Lift Off) process may be used to remove the sacrificial layer and the base layer, wherein the material constituting the sacrificial layer includes amorphous silicon, polyimide and other materials suitable for the laser lift off process.

A sacrificial layer is formed on the base layer, and then the sacrificial layer is removed when the base layer is removed. The sacrificial layer can facilitate the removal of the base layer and reduce the difficulty of removing the base layer.

205. Form a piezoelectric layer on the second surface of the first electrode.

The second surface of the first electrode is on the side of the first electrode away from the passivation protection layer.

Optionally, the piezoelectric material constituting the piezoelectric layer includes polyvinylidene fluoride (PVDF), aluminum nitride, etc., and the embodiment of the present application does not specifically limit the piezoelectric material constituting the piezoelectric layer. The preparation process of forming the piezoelectric layer includes coating, filming, physical vapor deposition (Physical Vapor Deposition, PVD) process, chemical vapor deposition (Chemical Vapor Deposition, CVD) process, etc. The embodiments of the present application discuss the formation of the piezoelectric layer. The process is not specifically limited. It should be noted that the process of forming the piezoelectric layer can be set by those skilled in the art according to the requirements of the piezoelectric material constituting the piezoelectric layer. For example, when the piezoelectric material constituting the piezoelectric layer is polyvinylidene fluoride (PVDF) When the piezoelectric layer can be formed by coating, sticking, etc., when the piezoelectric material constituting the piezoelectric layer is aluminum nitride, a physical vapor deposition process or a chemical vapor deposition process can be used to form the piezoelectric layer.

Optionally, the process of disposing the upper electrode on the lower surface of the piezoelectric layer includes an electroplating process, etc. The embodiment of the present application does not specifically limit the process of disposing the upper electrode on the lower surface of the piezoelectric layer. As shown in FIG. 13, the piezoelectric layer 308 is formed on the second surface of the first electrode 302.

206. Form a second electrode on the first surface of the piezoelectric layer.

The first surface of the piezoelectric layer is on the side of the piezoelectric layer away from the first electrode. It should be noted that the second electrode can be formed in the same manner as the first electrode, and will not be repeated here. As shown in FIG. 14, the second electrode 309 is formed on the first surface of the piezoelectric layer 308.

Optionally, after the second electrode is formed on the first surface of the piezoelectric layer, the method further includes: partially removing the piezoelectric layer to expose the first electrode, and electrically connect the exposed part of the first electrode to the second electrode. connect. As shown in FIG. 15, the exposed portion of the first electrode 302 is electrically connected to the second electrode 309.

In the method for manufacturing an ultrasonic transducer provided by the embodiment of the present application, a first electrode is formed on a base layer; a passivation protection layer is formed on the first surface of the first electrode; a circuit layer is formed on the first surface of the passivation protection layer; removal Base layer; forming a piezoelectric layer on the second surface of the first electrode; forming a second electrode on the first surface of the piezoelectric layer. Because of the removal of the base layer, the thickness of the ultrasonic transducer is small, which can be applied to scenes that require ultra-thin ultrasonic transducers. Moreover, the effective device structure layer through which the ultrasonic signal generated by the ultrasonic transducer propagates does not include the base layer, which prevents energy loss due to the penetration of the ultrasonic signal through the base layer, and makes the ultrasonic performance of the ultrasonic transducer better.

Example two

Based on the preparation method of the ultrasonic transducer provided in the first embodiment, the second embodiment of the present application provides a preparation method of the ultrasonic transducer. The preparation method of the ultrasonic transducer described in the first embodiment will be further described in detail, as As shown in Figure 16, the method includes the following steps:

301. A sacrificial layer is formed on the base layer, and a first electrode is formed on the first surface of the sacrificial layer.

The first surface of the sacrificial layer is on the side of the sacrificial layer away from the base layer, and the second surface of the sacrificial layer is on the side of the sacrificial layer close to the base layer.

302. Form a passivation protection layer on the first surface of the first electrode.

The first surface of the first electrode is on the side of the first electrode away from the sacrificial layer, which can also be said to be the side away from the base layer; the second surface of the first electrode is on the side of the first electrode close to the sacrificial layer, which can also be said It is the side close to the base layer.

303. Form a circuit layer on the first surface of the passivation protection layer.

The first surface of the passivation protection layer is on the side of the passivation protection layer away from the first electrode, and the second surface of the passivation protection layer is on the side of the passivation protection layer close to the first electrode.

304. Form a functional layer on the first surface of the circuit layer.

The first surface of the circuit layer is on the side of the circuit layer away from the passivation protection layer, and the second surface of the circuit layer is on the side of the circuit layer close to the passivation protection layer.

Specifically, the material constituting the functional layer includes epoxy resin and the like. Illustratively, the functional layer includes epoxy resin film. The process of forming the functional layer may be a molding process or other film layer preparation processes. Among them, the molding process includes a wafer level molding process, etc. The film preparation process includes a physical vapor deposition (Physical Vapor Deposition, PVD) process, a chemical vapor deposition (Chemical Vapor Deposition, CVD) process, etc. The embodiment of the present application does not specifically limit the process of forming the functional layer.

The thickness of the functional layer can range from 30 um to 500 um, and the thickness of the functional layer can be set by those skilled in the art according to the thickness requirements of the ultrasonic transducer. Different preparation processes are used to form the functional layer, and the thickness of the functional layer has different value ranges. It should be noted that a functional layer with a thickness that meets the requirements can be directly formed when the functional layer is formed, or after the formed functional layer reaches a certain thickness (for example, 100-600um), the thickness of the functional layer can be precisely adjusted by a process such as grinding.

305. Form a first opening that reaches the circuit layer on the first surface of the functional layer, and perform circuit layer deposition and imaging processing to form an electrical connection terminal that is electrically connected to the circuit layer through the first opening.

The first surface of the functional layer is on the side of the functional layer away from the circuit layer, and the second surface of the functional layer is on the side of the functional layer close to the circuit layer.

306. A second opening reaching the circuit layer is formed on the first surface of the functional layer.

The first surface of the functional layer is on the side of the functional layer away from the circuit layer. The functional layer may be a flexible dielectric. Combining the third application scenario and the fourth application scenario in step 203, here, a reflective surface can be formed on the functional layer or an acoustic impedance matching material can be filled. For example, a second opening that reaches the circuit layer can be formed on the first surface of the functional layer, so that the portion of the first surface of the circuit layer exposed at the second opening forms a signal reflection surface; or, it can be in the second opening. The hole is filled with acoustic impedance matching material to reduce signal energy loss.

307. Remove the base layer and the sacrificial layer.

308. Form a piezoelectric layer on the second surface of the first electrode.

309. Form a second electrode on the first surface of the piezoelectric layer.

The first surface of the piezoelectric layer is on the side of the piezoelectric layer away from the first electrode (or close to the second electrode), and the second surface of the piezoelectric layer is close to the first electrode (or away from the second electrode) on the piezoelectric layer On the side.

310. Partially remove the piezoelectric layer to expose the first electrode, and electrically connect the exposed part of the first electrode to the second electrode.

It should be noted that the processes described in steps 301-310 are all described in detail in Embodiment 1, and will not be repeated here. In the second embodiment, the functional layer is not only provided with a first opening to form an electrical connection terminal electrically connected to the circuit layer through the first opening, so that the circuit layer can be connected to the outside through the electrical connection terminal; and the functional layer is also provided with a second The second opening can form a reflective surface, or fill the second opening with an acoustic impedance matching material, which can increase the energy of the signal, or increase the signal strength, reduce energy loss, and enhance the ultrasonic performance of the ultrasonic transducer; the functional layer also It can play a supporting role, and the functional layer can be a flexible dielectric. The functional layer is thinner than the base layer and occupies less space, reducing the energy loss caused by the ultrasonic signal penetrating the base layer, and it can be applied to scenarios that require flexible ultrasonic transducers In, the scope of application is more extensive.

Example three

Based on the ultrasonic transducer manufacturing methods provided in the first and second embodiments above, the third embodiment of the present application provides an ultrasonic transducer, which can pass the method described in the first or second embodiment above. The ultrasonic transducer is prepared by the preparation method. As shown in FIG. 17, FIG. 17 is a schematic structural diagram of an ultrasonic transducer provided by an embodiment of the application.

The ultrasonic transducer includes a functional layer 401, a circuit layer 402, a piezoelectric layer 403, a passivation protection layer 404, a first electrode 405, and a second electrode 406.

The functional layer 401 is a flexible dielectric; the circuit layer 402 is disposed between the functional layer 401 and the passivation protection layer 404; the first electrode 405 is disposed on the side of the passivation protection layer 404 away from the circuit layer 402; the piezoelectric layer 403 is disposed on the first An electrode 405 is away from the side of the passivation protection layer 404, and the piezoelectric layer 403 is located between the first electrode 405 and the second electrode 406.

Optionally, the circuit layer may be a complementary metal oxide semiconductor (Complementary Metal Oxide Semiconductor, CMOS) circuit layer, or a thin film transistor (Thin Film Transistor, TFT) circuit layer. The circuit layer may include the control circuit of the ultrasonic transducer.

The material constituting the functional layer includes epoxy resin and the like. Illustratively, the functional layer includes an epoxy resin film. The thickness of the functional layer can range from 30 um to 500 um, and the thickness of the functional layer can be set by those skilled in the art according to the thickness requirements of the ultrasonic transducer. If different preparation processes are used to prepare the functional layer, the thickness range of the functional layer is different.

The piezoelectric material constituting the piezoelectric layer includes polyvinylidene fluoride (PVDF), aluminum nitride, etc., and the embodiment of the present application does not specifically limit the piezoelectric material constituting the piezoelectric layer.

Optionally, as shown in FIG. 18, the functional layer 401 is provided with a first opening 4011 from the first surface of the functional layer 401 to the circuit layer 402, and the first surface of the functional layer 401 is on the functional layer 401 away from the circuit layer 402. One side; the second surface of the functional layer 401 is provided with an electrical connection terminal 4012, and the electrical connection terminal 4012 is electrically connected to the circuit layer 402 through the first opening 4011.

Through the first opening, the circuit layer can be connected to the outside through the electrical connection end, which makes the circuit design more flexible.

Optionally, as shown in FIG. 19, the functional layer 401 is provided with a second opening 4013 from the first surface of the functional layer 401 to the circuit layer 402, so that the first surface of the circuit layer 402 is in the second opening 4013. The exposed part forms a signal reflection surface, and the first surface of the functional layer 401 is on the side of the functional layer 401 away from the circuit layer 402.

The exposed portion at the second opening, that is, the interface between the air and the circuit layer, can form a signal reflection surface. The second opening can also be filled with reflective material to improve the reflection effect.

Optionally, as shown in FIG. 20, the functional layer 401 is provided with a third opening 4013 from the first surface of the functional layer 401 to the circuit layer 402, and the first surface of the functional layer 401 is on the functional layer 401 away from the circuit layer 402. One side; the third opening 4013 is filled with an acoustic impedance matching material 407 for reducing signal energy loss.

Filling the acoustic impedance matching material at the third opening of the functional layer can not only support the circuit layer, but also improve the signal strength.

Optionally, as shown in FIG. 21, the first electrode 405 is electrically connected to the second electrode 406 through the position where the piezoelectric layer 403 does not cover the first electrode 405.

The ultrasonic transducer provided by the embodiment of the present application, because the base layer is removed, makes the thickness of the ultrasonic transducer small, and can be suitable for scenarios requiring ultra-thin ultrasonic transducers. Moreover, the effective device structure layer through which the ultrasonic signal generated by the ultrasonic transducer propagates does not include the base layer, which prevents energy loss due to the penetration of the ultrasonic signal through the base layer, and makes the ultrasonic performance of the ultrasonic transducer better.

Embodiment four

Based on the preparation methods of the ultrasonic transducer provided in the first and second embodiments above, and the ultrasonic transducer provided in the third embodiment above, the fourth embodiment of the present application provides an information acquisition element, and the information acquisition element includes an ultrasonic transducer Array, the ultrasonic transducer array is an array composed of at least two ultrasonic transducers as described in the third embodiment.

Exemplarily, as shown in FIG. 22, the information collection element 500 includes an ultrasonic transducer array 501, and the ultrasonic transducer array 501 is an array composed of at least two ultrasonic transducers 502.

Optionally, in an embodiment of the present application, one or more corresponding opening structures are provided under the ultrasonic transducer array, and the opening structures may be the second in the functional layer described in the first embodiment. Opening or third opening.

Exemplarily, as shown in FIG. 22, the ultrasonic transducer array 501 is an array composed of at least two ultrasonic transducers 502, and an opening corresponding to each ultrasonic transducer 502 is provided under the ultrasonic transducer array 501.孔结构5021。 Hole structure 5021.

Exemplarily, as shown in FIG. 23, an opening structure 5022 corresponding to the ultrasonic transducer array 501 is provided under the ultrasonic transducer array 501.

In the information collection element provided by the embodiment of the present application, one or more corresponding opening structures are provided under the ultrasonic transducer array, which can improve the ultrasonic performance of the ultrasonic transducer.

It should also be noted that the terms "include", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or equipment including a series of elements includes not only those elements, but also Other elements that are not explicitly listed, or include elements inherent to such processes, methods, commodities, or equipment. If there are no more restrictions, the element defined by the sentence "including a..." does not exclude the existence of other identical elements in the process, method, commodity or equipment that includes the element.

The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, as for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for related parts, please refer to the part of the description of the method embodiment.

The above descriptions are only examples of this application, and are not intended to limit this application. For those skilled in the art, this application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this application shall be included in the scope of the claims of this application.

Claims

A method for preparing an ultrasonic transducer, which is characterized in that it comprises:

Forming a first electrode on the base layer;

Forming a passivation protection layer on the first surface of the first electrode, and the first surface of the first electrode is on the side of the first electrode away from the base layer;

Forming a circuit layer on the first surface of the passivation protection layer, and the first surface of the passivation protection layer is on the side of the passivation protection layer away from the first electrode;

Removing the base layer;

Forming a piezoelectric layer on the second surface of the first electrode, and the second surface of the first electrode is on the side of the first electrode away from the passivation protection layer;

A second electrode is formed on the first surface of the piezoelectric layer, and the first surface of the piezoelectric layer is on the side of the piezoelectric layer away from the first electrode.
The method for manufacturing an ultrasonic transducer according to claim 1, wherein after the circuit layer is formed on the first surface of the passivation protection layer, the method further comprises:

Forming a functional layer on the first surface of the circuit layer, and the first surface of the circuit layer is on the side of the circuit layer away from the passivation protection layer;

Forming a first opening reaching the circuit layer on the first surface of the functional layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer;

Perform circuit layer deposition and image processing on the first surface of the functional layer to form an electrical connection terminal electrically connected to the circuit layer through the first opening, so that the circuit layer passes through the electrical connection terminal Connect with the outside.
The method for manufacturing an ultrasonic transducer according to claim 1, wherein after the circuit layer is formed on the first surface of the passivation protection layer, the method further comprises:

Forming a functional layer on the first surface of the circuit layer, and the first surface of the circuit layer is on the side of the circuit layer away from the passivation protection layer;

A second opening reaching the circuit layer is formed on the first surface of the functional layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer, so that the On the first surface, the portion exposed at the second opening forms a signal reflection surface.
The method for manufacturing an ultrasonic transducer according to claim 1, wherein after the circuit layer is formed on the first surface of the passivation protection layer, the method further comprises:

Forming a functional layer on the first surface of the circuit layer, and the first surface of the circuit layer is on the side of the circuit layer away from the passivation protection layer;

Forming a third opening that reaches the circuit layer on the first surface of the functional layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer;

The third opening is filled with an acoustic impedance matching material for reducing signal energy loss.
The method for manufacturing an ultrasonic transducer according to claim 1, wherein after the circuit layer is formed on the first surface of the passivation protection layer, the method further comprises:

A matching layer is formed on the first surface of the circuit layer, the first surface of the circuit layer is on the side of the circuit layer away from the passivation protection layer, and the matching layer includes an acoustic impedance for reducing signal energy loss Matching materials.
The method for manufacturing an ultrasonic transducer according to claim 1, wherein after the second electrode is formed on the first surface of the piezoelectric layer, the method further comprises:

Part of the piezoelectric layer is removed to expose the first electrode, and the exposed part of the first electrode is electrically connected to the second electrode.
The method for manufacturing an ultrasonic transducer according to any one of claims 1-6, wherein the forming the first electrode on the base layer comprises:

Forming a sacrificial layer on the base layer, and forming the first electrode on a first surface of the sacrificial layer, and the first surface of the sacrificial layer is on the side of the sacrificial layer away from the base layer;

The removing the base layer includes:

The base layer and the sacrificial layer are removed.
An ultrasonic transducer, characterized by comprising: a functional layer, a circuit layer, a piezoelectric layer, a passivation protection layer, a first electrode and a second electrode;

The functional layer is a flexible dielectric;

The circuit layer is arranged between the functional layer and the passivation protection layer;

The first electrode is arranged on a side of the passivation protection layer away from the circuit layer;

The piezoelectric layer is disposed on a side of the first electrode away from the passivation protection layer, and the piezoelectric layer is located between the first electrode and the second electrode.
The ultrasonic transducer according to claim 8, wherein:

The functional layer is provided with a first opening from the first surface of the functional layer to the circuit layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer;

An electrical connection terminal is provided on the second surface of the functional layer, and the electrical connection terminal is electrically connected to the circuit layer through the first opening.
The ultrasonic transducer according to claim 8, wherein:

The functional layer is provided with a second opening from the first surface of the functional layer to the circuit layer, so that the portion of the first surface of the circuit layer exposed at the second opening forms a signal The reflective surface, the first surface of the functional layer is on the side of the functional layer away from the circuit layer.
The ultrasonic transducer according to claim 8, wherein:

The functional layer is provided with a third opening from the first surface of the functional layer to the circuit layer, and the first surface of the functional layer is on the side of the functional layer away from the circuit layer;

The third opening is filled with an acoustic impedance matching material for reducing signal energy loss.
The ultrasonic transducer according to any one of claims 8-11, characterized in that,

The first electrode is electrically connected to the second electrode through the position where the piezoelectric layer does not cover the first electrode.

An information acquisition element, wherein the information acquisition element comprises an ultrasonic transducer array, and the ultrasonic transducer array is composed of at least two ultrasonic transducers according to any one of claims 8-12. An array of devices.