Patent Publication Number: US-2023157179-A1

Title: Piezoelectric element, piezoelectric vibrator and manufacturing method and driving method thereof, and electronic device

Description:
TECHNICAL FIELD 
     The application relates to the field of piezoelectric technologies, in particular to a piezoelectric element, a piezoelectric vibrator and a manufacturing method and a driving method thereof, and an electronic device. 
     BACKGROUND 
     With the rapid development of electronic technologies, users seek ever higher requirements for usage experience. However, most existing electronic devices can only provide visual and acoustic experience, and cannot provide haptic experience for users. So, the haptic rendering technique emerges. 
     At present, the haptic rendering technique is adopted to provide haptic feedback by means of vibrations of piezoelectric elements configured in electronic devices. However, when existing piezoelectric elements are used, the temperature of the piezoelectric elements may rise due to vibrations of the piezoelectric structure, resulting in a breakdown of the piezoelectric structure and affecting the resonance frequency of the piezoelectric structure. 
     SUMMARY 
     Some embodiments of the disclosure provide the following technical solutions: 
     In a first aspect, the disclosure provides a piezoelectric element, comprising a first electrode and a piezoelectric structure disposed on the first electrode, wherein in a direction perpendicular to a plane where the first electrode is located, the piezoelectric structure has an opening penetrating the piezoelectric structure and exposing part of the first electrode; 
     Optionally, a heat conducting structure has a thickness of 3 μm-5 μm, the piezoelectric structure has a thickness less than 5 μm, and a second electrode has a thickness of 100 nm-1000 nm. 
     In a second aspect, the disclosure provides a piezoelectric vibrator, comprising a substrate and at least one piezoelectric element disposed on the substrate, wherein the heat conductivity of the heat conducting structure is greater than that of the substrate. 
     In a third aspect, the disclosure provides a manufacturing method of a piezoelectric vibrator, comprising: 
     Forming at least one first electrode on the substrate. 
     In a fourth aspect, the disclosure provides a driving method of a piezoelectric vibrator, being used for driving the piezoelectric vibrator and comprising: 
     Inputting a first driving signal to the first electrode of the piezoelectric element, and inputting a second driving signal to the second electrode in the piezoelectric element. 
     In a fifth aspect, the disclosure provides an electronic device, comprising the piezoelectric vibrator. 
     In the embodiments of the disclosure, a piezoelectric structure is disposed on a first electrode and has an opening allowing the first electrode to penetrate through to be partially exposed in a direction perpendicular to a plane where the first electrode is located, a heat conducting structure is disposed in the opening, and an orthographic projection of the heat conducting structure on the first electrode does not overlap with an orthographic projection of the piezoelectric structure on the first electrode. The opening penetrating through the piezoelectric structure is formed in the piezoelectric structure, such that the area of the piezoelectric structure in the piezoelectric element is decreased, the heating area is decreased when the piezoelectric structure vibrates, and heat generated by the piezoelectric structure is reduced, correspondingly; in addition, the heat conducting structure is additionally disposed in the piezoelectric element to dissipate heat generated when the piezoelectric structure vibrates, such that the heat-dissipation property of the piezoelectric element is improved, the problems that the piezoelectric structure is broken down and the resonance frequency of the piezoelectric structure is affected due to excessively high temperature of the piezoelectric element are solved, and the reliability of the piezoelectric structure is improved. 
     The aforesaid description is merely a brief summary of the technical solution of the disclosure. To allow those skilled in the art to gain a better understanding of the technical means of the disclosure so as to implement the disclosure according to the contents in the specification and to make the above and other purposes, features and advantages of the disclosure clearer, specific implementations of the disclosure are given below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To more clearly explain the technical solutions of the embodiments of the disclosure or related arts, drawings for describing the embodiments of the disclosure or the related arts will be briefly introduced below. Obviously, the drawings in the following description only illustrate some embodiments of the disclosure, and those ordinarily skilled in the art can obtain other drawings according to the following ones without creative labor. 
         FIG.  1    illustrates a sectional view of a piezoelectric element according to one embodiment of the disclosure; 
         FIG.  2    illustrates a plan view of the piezoelectric element according to one embodiment of the disclosure; 
         FIG.  3    illustrates a sectional view of another piezoelectric element according to one embodiment of the disclosure; 
         FIG.  4    illustrates a plan view of a piezoelectric vibrator according to one embodiment of the disclosure; 
         FIG.  5    illustrates a sectional view of a piezoelectric vibrator according to one embodiment of the disclosure; 
         FIG.  6    illustrates a flow diagram of a manufacturing method of a piezoelectric vibrator according to one embodiment of the disclosure; and 
         FIG.  7    illustrates an XRD spectrum of a piezoelectric structure according to one embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     To clarify the purposes, technical solutions and advantages of the embodiments of the disclosure, the technical solutions of the embodiments of the disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the disclosure. Obviously, the embodiments in the following description are merely illustrative ones, and are not all possible ones of the disclosure. All other embodiments obtained by those ordinarily skilled in the art based on the following ones without creative labor should also fall within the protection scope of the disclosure. 
       FIG.  1    illustrates a sectional view of a piezoelectric element according to one embodiment of the disclosure,  FIG.  2    illustrates a plan view of the piezoelectric element according to one embodiment of the disclosure, and the sectional view illustrated by  FIG.  1    is a sectional view along A-A′ in  FIG.  2   . 
     One embodiment of the disclosure provides a piezoelectric element  10 , comprising: a first electrode  11  and a piezoelectric structure  12  disposed on the first electrode  11 , wherein in a direction perpendicular to a plane where the first electrode  11  is located, the piezoelectric structure  12  has an opening allowing the first electrode  11  to penetrate through to be partially exposed. The piezoelectric element  10  further comprises a heat conducting structure  13  disposed in the opening, and an orthographic projection of the heat conducting structure  13  on the first electrode  11  does not overlap with an orthographic projection of the first piezoelectric structure  12  on the first electrode  11 . 
     In an actual product, the first electrode  11  refers to a bottom electrode of the piezoelectric element  10 , and the first electrode  11  may be a planar electrode and is rectangular. The first electrode  11  is made of a transparent electrically conductive material such as Indium Tin Oxides (ITO), and in the direction perpendicular to the plane where the first electrode  11  is located, the thickness h 1  of the first electrode  11  is 100 nm-1000 nm. Certainly, the first electrode  11  may also be made of common metallic materials such as gold (Au) and indium (In). Considering that light may not penetrate through the first electrode  11  if the metallic materials are too thick, the thickness h 1  of the first electrode  11  is set to be less than or equal to 20 nm when the first electrode  11  is made of the metallic materials. 
     The piezoelectric structure  12  is disposed on the first electrode  11 , and the orthographic projection of the piezoelectric structure  12  on the first electrode  11  is located in the area of the first electrode  11 . The orthographic projection of the piezoelectric structure  12  on the first electrode  11  is annular; and in the direction perpendicular to the plane where the first electrode  11  is located, the piezoelectric structure  12  has the opening allowing the first electrode  11  to penetrate through to be partially exposed, and the opening may be of any closed shapes, such as rectangular, circular and hexagonal. 
     Wherein, the piezoelectric structure  12  is made of piezoelectric ceramic (PZT). For example, the piezoelectric ceramic may be made of PZT binary system piezoelectric ceramic, which has a chemical formula of Pb(Zr 1-x Ti x )O 3  and is of a ABO 3  perovskite structure. 
     When the opening penetrating through the piezoelectric structure  12  is formed in the piezoelectric structure  12 , the area of the piezoelectric structure  12  in the piezoelectric element  10  is decreased, the heating area is decreased when the piezoelectric structure  12  vibrates, and heat generated by the piezoelectric structure  12  is reduced, correspondingly. 
     In addition, the heat conducting structure  13  is disposed in the opening formed in the piezoelectric structure  12  to dissipate heat generated when the piezoelectric structure  12  vibrates, such that the heat-dissipation property of the piezoelectric element  10  is improved. 
     When the heat-dissipation property of the piezoelectric element  10  is poor, the temperature of the piezoelectric element  10  will rise, which in turn reduces a potential barrier between electrodes on two sides of the piezoelectric structure  12 , and electron transfer may occur between the electrodes on the two sides of the piezoelectric structure  12  and result in a breakdown of the piezoelectric structure  12 ; in addition, when the temperature of the piezoelectric structure  12  rises, the dielectric loss of the piezoelectric structure  12  will be increased, which will further increase the temperature of the piezoelectric element  10  and result in a breakdown of the piezoelectric structure  12 ; moreover, when the temperature of the piezoelectric element  10  rises, the resonance frequency of the piezoelectric structure  12  will be decreased, and consequentially, the frequency of the piezoelectric structure  12  will be unable to meet requirements when the piezoelectric structure  12  vibrates. 
     In this embodiment of the disclosure, the heat-dissipation property of the piezoelectric element  10  is improved by reducing the heating area of the piezoelectric structure  12  and adding the heat conducting structure  13  in the piezoelectric element  10 , such that the temperature of the piezoelectric element  10  is prevented from being excessively high, the piezoelectric structure  12  is effectively prevented from being broken down, it is ensured that the frequency of the piezoelectric structure  12  meets actual requirement when the piezoelectric structure  12  vibrates, and the reliability of the piezoelectric structure  12  is improved; in addition, the temperature around the piezoelectric element  10  is also decreased, and the situation where the haptic feeling of users is affected due to excessively high temperature is avoided. 
     In addition, in an actual product, an orthographic projection of the heat conducting structure  13  on the first electrode  11  does not overlap with the orthographic projection of the piezoelectric structure  12  on the first electrode  11 , that is to say, the heat conducting structure  13  does not contact with the piezoelectric structure  12 . Considering that the heat conducting structure  13  will affect the vibration effect of the piezoelectric structure  12  if contacting with the piezoelectric structure  12 , the orthographic projection of the heat conducting structure  13  on the first electrode  11  is prevented from overlapping with the orthographic projection of the piezoelectric structure  12  on the first electrode  11  in this embodiment of the disclosure, such that the vibration effect of the piezoelectric structure  12  is improved. 
     In this embodiment of the disclosure, the heat conducting structure  13  is made of a heat conducting metal, such as a metallic material with a high heat conductivity like aluminum (Al) or copper (Cu), wherein the heat conductivity of aluminum is 237 w/(m·k). 
     Of course, the heat conducting structure  13  may also be made of other transparent heat conducting materials such as aluminum nitride, boron nitride, silicon carbide, magnesium oxide and aluminum oxide, wherein the heat conductivity of the aluminum nitride is 80-320 w/(m·k), the heat conductivity of the boron nitride is 125 w/(m·k), the heat conductivity of the silicon carbide is 83.6 w/(m·k), the heat conductivity of the magnesium oxide is 36 w/(m·k), and the heat conductivity of the aluminum oxide is 30 w/(m·k). 
     When the heat conducting structure  13  is made of aluminum, the cost and manufacturing process difficulty of the heat conducting structure  13  may be reduced. 
     Specifically, the opening ratio of the piezoelectric structure  12  is 10%-70%. The opening ratio of the piezoelectric structure  12  refers to the ratio of the area of an orthographic projection of the opening in the piezoelectric element  10  on the first electrode  11  to the sum of the area of the orthographic projection of the piezoelectric structure  12  on the first electrode  11  and the area of the orthographic projection of the opening on the first electrode  11 , namely the ratio of the area of the orthographic projection of the opening on the first electrode  11  to the area of a closed pattern defined by an orthographic projection of a side, away from the opening, of the piezoelectric structure  12  on the first electrode  11 . 
     As shown in  FIG.  3   , the piezoelectric element  10  further comprises a second electrode  14  disposed on a side, away from the first electrode  11 , of the piezoelectric structure  12 , and an orthographic projection of the second electrode  14  on the first electrode  11  is located within the orthographic projection of the piezoelectric structure  12  on the first electrode  11 . 
     The second electrode  14  is disposed on the side, away from the first electrode  11 , of the piezoelectric structure  12 , and is a top electrode of the piezoelectric element  10 , and the orthographic projection of the second electrode  14  on the first electrode  11  is also annular. The second electrode  14  may be made of a transparent electrically conductive material such as ITO. Of course, the second electrode  14  may also be made of common metallic materials such as Au and In, and the thickness h 1  of the first electrode  11  may be equal to the thickness h 4  of the second electrode  14 . 
     In an actual product, the orthographic projection of the second electrode  14  on the first electrode  11  may overlap with the orthographic projection of the piezoelectric structure  12  on the first electrode  11 , but the area of the orthographic projection of the second electrode  14  on the first electrode  11  is smaller than the area of the orthographic projection of the piezoelectric structure  12  on the first electrode  11  under the influence of the process, that is, the orthographic projection of the second electrode  14  on the first electrode  11  is located within the orthographic projection of the piezoelectric structure  12  on the first electrode  11 , such that the second electrode  14  will not cover the opening of the piezoelectric structure  12 . 
     In this embodiment of the disclosure, in the direction perpendicular to the plane where the first electrode  11  is located, the thickness h 2  of the heat conducting structure  13  is less than or equal to the sum of the thickness of the piezoelectric structure  12  and the thickness of the second electrode  14 . 
     As shown in  FIG.  3   , the thickness of the piezoelectric structure  12  is h 3 , the thickness of the second electrode  14  is h 4 , and the thickness h 2  of the heat conducting structure  13  is smaller than or equal to (h 3 +h 4 ); and the thickness h 2  of the heat conducting structure  13  is greater than the thickness h 3  of the piezoelectric structure  12 . 
     The thickness h 2  of the heat conducting structure  13  is less than or equal to the sum of the thickness of the piezoelectric structure  12  and the thickness of the second electrode  14 , and the thickness h 2  of the heat conducting structure  13  is greater than the thickness h 3  of the piezoelectric structure  12 , such that the surface area of the heat conducting structure  13  is enlarged, thus improving the heat-dissipation effect of the heat conducting structure  13 . 
     Wherein, the thickness h 2  of the heat conducting structure  13  is 3 μm-5 μm, the thickness h 3  of the piezoelectric structure  12  is less than 5 μm, and the thickness h 4  of the second electrode  14  is 100 nm-1000 nm. 
     For example, the thickness h 2  of the heat conducting structure  13  is set as 3.5 μm, the thickness h 3  of the piezoelectric structure  12  is set as 3 μm, and the thickness h 4  of the second electrode  14  is set as 600 nm, such that the thickness h 2  of the heat conducting structure  13  is smaller than or equal to the sum of the thickness of the piezoelectric structure  12  and the thickness of the second electrode  14 . 
     It is proved by testing that the piezoelectric element  10  in this embodiment of the disclosure is able to greatly reduce a temperature rise caused by vibrations of the piezoelectric structure  12 , and the temperature may be decreased by 50% without affecting the performance of the piezoelectric element  10 . 
     In this embodiment of the disclosure, the opening penetrating through the piezoelectric structure is formed in the piezoelectric structure, such that the area of the piezoelectric structure in the piezoelectric element is decreased, the heating area of the piezoelectric structure is decreased when the piezoelectric structure vibrates, and heat generated by the piezoelectric structure is reduced, correspondingly; in addition, the heat conducting structure is additionally disposed in the piezoelectric element to dissipate heat generated when the piezoelectric structure vibrates, such that the heat-dissipation property of the piezoelectric element is improved, the problems that the piezoelectric structure is broken down and the resonance frequency of the piezoelectric structure is affected due to excessively high temperature of the piezoelectric element are solved, and the reliability of the piezoelectric structure is improved. 
       FIG.  4    illustrates a plan view of a piezoelectric vibrator according to one embodiment of the disclosure,  FIG.  5    illustrates a sectional view of the piezoelectric vibrator according to one embodiment of the disclosure, and the sectional view illustrated by  FIG.  5    is a sectional view along B-B′ in  FIG.  4   . 
     One embodiment of the disclosure further provides a piezoelectric vibrator, comprising a substrate  20  and at least one piezoelectric element  10  disposed on the substrate  20 , wherein the heat conductivity of the heat conducting structure  13  is greater than that of the substrate  20 . 
     Wherein, the substrate  20  may be a flexible substrate or a rigid substrate. For example, the flexible substrate may be made of PI (Polyimide), PET (Polyethylene Terephthalate), or PDMS (Polydimethylsiloxane), and the rigid substrate may be made of glass. 
     At least one piezoelectric element  10  is disposed on the substrate  20 . Specifically, the substrate  20  is disposed on a side, away from the piezoelectric structure  12 , of the first electrode  11 , that is, the substrate  20  directly contacts with the first electrode  11  in the piezoelectric element  10 . 
     If each piezoelectric element  10  is not provided with the heat conducting structure  13 , heat generated due to vibrations of the piezoelectric structure  12  in the piezoelectric element  10  will be transmitted to the substrate  20  via the first electrode  11  and is then dissipated by the substrate  20 , but the heat conductivity of the substrate  20  is low, for example, the heat conductivity of a glass substrate is only 1.22 w/(m·k), and heat will be accumulated on the piezoelectric element  10  due to the unsatisfying heat-dissipation effect of the substrate  20 , thus increasing the temperature of the piezoelectric element  10 . 
     In this embodiment of the disclosure, the heat conducting structure  13  is additionally disposed in each piezoelectric element  10 , heat generated due to vibrations of the piezoelectric structure  12  in the piezoelectric element  10  is transferred to the heat conducting structure  13  via the first electrode  11 , or the heat is transferred to the substrate  20  via the first electrode  11  and is then transferred to the heat conducting structure  13  via the substrate  20  and the first electrode  11 , and the heat conductivity of the heat conducting structure  13  is superior to that of the substrate  20 , such that the heat-dissipation effect of the heat conducting structure  13  is better, thus preventing heat from being accumulated on the piezoelectric element  10  and preventing the temperature of the piezoelectric element  10  from being too high. 
     Furthermore, the piezoelectric vibrator further comprises a first signal line connected to each first electrode  11  and a second signal line connected to each second electrode  14 , wherein the first signal lines are used for providing first driving signals for the first electrodes  11 , and the second signal lines are used for providing second driving signals for the second electrodes  14 . Wherein, the first signal lines and the second signal lines are made of electrically conductive materials. For example, the first signal lines and the second signal lines are made of metal, alloy, or the like. 
     It should be noted that the first electrodes  11  and the second electrodes  14  of any two adjacent piezoelectric elements  10  in the piezoelectric vibrator are disconnected, such that vibrations of each piezoelectric element  10  may be controlled separately. Or, the first electrodes  11  of all the piezoelectric elements  10  in the piezoelectric vibrator are of an integrated structure, that is, the first electrodes  11  of all the piezoelectric elements  10  in the piezoelectric vibrator are connected, and in this case, all the piezoelectric elements in the piezoelectric vibrator share the same first electrode  11 , and the second electrodes  14  are disconnected. 
     One embodiment of the disclosure further provides an electronic device, comprising the piezoelectric vibrator. 
     In an actual product, the electronic device may be a displaying device, comprising a display panel and the piezoelectric vibrator, wherein the piezoelectric vibrator may be disposed on an emission side of the display panel, such that the displaying device has both a display function and a haptic rendering function. 
     In some embodiments, the display panel of the displaying device is an embedded touch display panel. 
     In some embodiments, the displaying device further comprises a touch base plate disposed between the display panel and the piezoelectric vibrator. 
     Of course, the electronic device in this embodiment of the disclosure is not limited to the displaying device, and may be any other products or components with a haptic rendering function. 
     In this embodiment of the disclosure, an opening penetrating through the piezoelectric structure is formed in the piezoelectric structure, such that the area of the piezoelectric structure in the piezoelectric element is decreased, the heating area is decreased when the piezoelectric structure vibrates, and heat generated by the piezoelectric structure is reduced, correspondingly; in addition, a heat conducting structure is additionally disposed in the piezoelectric element to dissipate heat generated when the piezoelectric structure vibrates, such that the heat-dissipation property of the piezoelectric element is improved, the problems that the piezoelectric structure is broken down and the resonance frequency of the piezoelectric structure is affected due to excessively high temperature of the piezoelectric element are solved, and the reliability of the piezoelectric structure is improved. 
     Referring to  FIG.  6    which illustrates a flow diagram of a manufacturing method of a piezoelectric vibrator according to one embodiment of the disclosure, the manufacturing method may specifically comprise the following steps: 
     Step  601 : at least one first electrode is formed on a substrate. 
     In this embodiment of the disclosure, a substrate  20  is provided first, wherein the substrate  20  may be a flexible substrate or a rigid substrate; and then, at least one first electrode  11  is formed on the substrate  20  by a patterning process. 
     Specifically, a first electrode film is deposited on the substrate  20  and is then subjected to thermal annealing in a nitrogen environment to decrease the electrical resistivity of the first electrode film; then, the first electrode film is coated with a photoresist, and the photoresist is exposed and developed; and next, an area, with the photoresist being removed, of the first electrode film is etched, and the residual photoresist is removed, such that at least one first electrode  11  is formed on the substrate  20 , wherein the first electrode  11  may be made of ITO. 
     Step  602 : a piezoelectric structure is formed on each first electrode; and in a direction perpendicular to a plane where each first electrode is located, each piezoelectric structure has an opening allowing the first electrode to penetrate through to be partially exposed. 
     In this embodiment of the disclosure, after at least one first electrode  11  is formed on the substrate  20 , a piezoelectric structure  12  is formed on each first electrode  11 , and in the direction perpendicular to the plane where each first electrode  11  is located, each piezoelectric structure  12  has an opening allowing the first electrode to penetrate through to be partially exposed, wherein the opening ratio of each piezoelectric structure  12  is 10%-70%. 
     Specifically, step  602  comprises a sub-step S 6021 , a sub-step S 6022  and a sub-step S 6023 : 
     Sub-step S 6021 : a piezoelectric film covering the first electrodes and the substrate is formed; 
     Sub-step S 6022 : thermal annealing and laser annealing are performed on the piezoelectric film; 
     Sub-step S 6023 : the piezoelectric film is patterned to form the piezoelectric structure on each first electrode. 
     Optionally, after at least one first electrode  11  is formed on the substrate  20 , a piezoelectric film covering the first electrodes  11  and the substrate  20  is formed by a dry film coating method or a sol-gel method; next, the structure formed with the piezoelectric film is placed in an air environment at 550° C.-600° C. to be subjected to RTA (Rapid Thermal Annealing), the piezoelectric film is radiated with laser during thermal annealing to perform laser annealing on the piezoelectric film, and the grain size and degree of crystallization of the piezoelectric film are improved by performing thermal annealing and laser annealing on the piezoelectric film, thus reducing the dielectric loss of the piezoelectric film; and finally, after being subjected to thermal annealing and laser annealing, the piezoelectric film is coated with a photoresist, then the photoresist is exposed and developed, next, an area, with the photoresist being removed, of the piezoelectric film is etched, and finally, the residual photoresist is removed, such that the piezoelectric structure  12  is formed on each first electrode  11 . 
     It is detected by testing that the XRD (X-ray diffraction) spectrum in  FIG.  7    may be obtained by performing X-ray diffraction on the piezoelectric structure formed under different conditions, wherein the horizontal axis represents the X-ray diffraction angle, and the vertical axis represents the diffraction intensity. 
       FIG.  7    illustrates three diffraction curves which are respectively a diffraction curve of a piezoelectric structure obtained only by thermal annealing (such as at a temperature of 550° C.), a diffraction curve of a piezoelectric structure obtained by thermal annealing (such as at a temperature of 550° C.) and laser radiation for 30 s, and a diffraction curve of a piezoelectric structure obtained by thermal annealing (such as at a temperature of 550° C.) and laser radiation for 60 s. As can be seen from  FIG.  7   , each of the three diffraction curves has two diffraction peaks which are a diffraction peak of the piezoelectric structure along a crystal plane (100) and a diffraction peak of the piezoelectric structure along a crystal plane (110). 
     It can be known, by analysis, that the ratio of the diffraction intensity of the piezoelectric structure obtained only by thermal annealing along the crystal face (110) to the diffraction intensity of the piezoelectric structure along the crystal face (100) is 10:1; and the ratio of the diffraction intensity of the piezoelectric structure obtained by thermal annealing and laser radiation along the crystal face (110) to the diffraction intensity of the piezoelectric structure along the crystal face (100) is greater than 20:1, and the grain size of the piezoelectric structure is 30 nm-50 nm. Thus, the grain size and degree of crystallization of the piezoelectric structure  12  obtained by thermal annealing and laser radiation in this embodiment of the disclosure are improved, which in turn further decreases the dielectric loss of the piezoelectric structure  12 . It is proved by testing that the dielectric dissipation factor may be decreased below 0.01 and may be further decreased below 0.005. 
     It should be noted that the diffraction peak of Pt (platinum) in  FIG.  7    is mainly used as a reference crystal face for determining the actual diffraction intensities of the piezoelectric structure along the crystal face (110) and the crystal face (100), and the piezoelectric element  10  is not provided with a film layer made of Pt. 
     In addition, laser annealing may be performed during thermal annealing, that is, the piezoelectric film is radiated with laser in a thermal annealing environment. Or, laser annealing may be performed after thermal annealing and cooling are finished. However, the piezoelectric structure  12  obtained by performing thermal annealing and laser annealing on the piezoelectric film at the same time has better performance. 
     Thermal annealing is performed on the piezoelectric film at a temperature of 550° C.-600° C. If the temperature of thermal annealing is over 600° C., the substrate  20  may deform. So, in this embodiment of the disclosure, the temperature of thermal annealing is reasonably controlled to protect the substrate  20  against deformation under high temperature. When laser annealing is performed on the piezoelectric film, the time of laser radiation is related to the intensity of laser, the thickness of the piezoelectric film, and the like, and the embodiments of the disclosure have no limitation in this aspect. 
     Step  603 : a heat conducting structure is formed in each opening, wherein an orthographic projection of the heat conducting structure on the first electrode does not overlap with an orthographic projection of the piezoelectric structure on the first electrode. 
     In this embodiment of the disclosure, after the piezoelectric structure  12  is formed in each first electrode  11 , a heat conducting structure  13  is formed in the opening of each piezoelectric structure  12 , and the orthographic projection of the heat conducting structure  13  on the first electrode  11  does not overlap with the orthographic projection of the piezoelectric structure  12  on the first electrode  11 . 
     Specifically, a heat conducting film covering the piezoelectric structures  12  and the first electrodes  11  is formed and is then coated with a photoresist, and then, the photoresist is exposed and developed; next, an area, with the photoresist being removed, of the heat conducting film is etched, and finally, the residual photoresist is removed, such that the heat conducting structure  13  is formed in the opening of each piezoelectric structure  12 . 
     Optionally, after step  603 , the method further comprises: a second electrode is formed on a side, away from the first electrode, of each piezoelectric structure; and an orthographic projection of the second electrode on the first electrode is located within the orthographic projection of the piezoelectric structure on the first electrode. 
     After the heat conducting structure  13  is formed in the opening of each piezoelectric structure  12 , a second electrode film covering the heat conducting structures  13 , the piezoelectric structures  12 , the first electrodes  11  and the substrate  20  is formed and is then coated with a photoresist, and then, the photoresist is exposed and developed; next, an area, with the photoresist being removed, of the second electrode film is etched, and finally, the residual photoresist is removed, such that a second electrode  14  is formed on a side, away from the first electrode  11 , of each piezoelectric structure  12 , wherein the orthographic projection of the second electrode  14  on the first electrode  11  is located within the orthographic projection of the piezoelectric structure  12  on the first electrode  11 , and the second electrode  14  is also made of ITO. 
     The piezoelectric element  10  is polarized later to increase the piezoelectric constant of the piezoelectric structure  12  in the piezoelectric element  10 , such that the piezoelectric element  10  has a good piezoelectric property. 
     In this embodiment of the disclosure, the opening penetrating through the piezoelectric structure is formed in the piezoelectric structure, such that the area of the piezoelectric structure in the piezoelectric element is decreased, the heating area is decreased when the piezoelectric structure vibrates, and heat generated by the piezoelectric structure is reduced, correspondingly; in addition, the heat conducting structure is additionally disposed in the piezoelectric element to dissipate heat generated when the piezoelectric structure vibrates, such that the heat-dissipation property of the piezoelectric element is improved, the problems that the piezoelectric structure is broken down and the resonance frequency of the piezoelectric structure is affected due to excessively high temperature of the piezoelectric element are solved, and the reliability of the piezoelectric structure is improved. 
     One embodiment of the disclosure further provides a driving method of a piezoelectric vibrator. The driving method is used for driving the piezoelectric vibrator shown in  FIG.  4    and  FIG.  5    and comprises: 
     Step S 01 : a first driving signal is input to the first electrode of the piezoelectric element, and a second driving signal is input to the second electrode of the piezoelectric element, wherein the second driving signal is divided into a first stage and a second stage, the second driving signal in the first stage is a pulse signal, the voltage of the second driving signal in the second stage is a preset voltage, and the voltage of the first driving signal is also the preset voltage. 
     In an actual product, the first electrode  11  in each piezoelectric element  10  is connected to a first signal line, and the second electrode  14  in each piezoelectric element  10  is connected to a second signal line; and when vibrations of the piezoelectric structures  12  in any one or more piezoelectric elements  10  need to be controlled, first driving signals are input to the first electrodes  11  in the corresponding piezoelectric elements  10  through the first signal lines, and second driving signals are input the second electrodes  14  in the corresponding piezoelectric elements  10  through the second signal lines. 
     In addition, the second driving signal is divided into multiple cycles, and each cycle is divided into a first stage and a second stage, wherein the second driving signal in the first stage is a pulse signal and has a frequency greater than 500 Hz, the voltage of the second driving signal in the second stage is a preset voltage, and the voltage of the first driving signal in each stage is also the preset voltage. 
     The preset voltage may be 0V, that is, in the first stage, the second driving signal is a pulse signal, such that an electric field is formed by a pressure difference between the first electrode  11  and the second electrode  14  on two sides of the piezoelectric structure  12 , and the piezoelectric structure  12  vibrates under the effect of the electric field; and in the second stage, the voltage of the first driving signal and the voltage of the second driving signal are 0V, no pressure difference exists between the first electrode  11  and the second electrode  14 , and the piezoelectric structure  12  does not vibrate. 
     In an actual product, the first electrodes  11  may be grounded by means of the first signal lines; or, the first signal lines continuously input low-voltage signals to the first electrodes  11 . 
     In this embodiment of the disclosure, the piezoelectric element  10  is driven by duty rather than being driven continuously, that is, the piezoelectric structure  12  is controlled to vibrate in the first stage in one cycle, and is controlled not to vibrate in the second stage of this cycle, and the piezoelectric structure  12  is controlled to vibrate again in the first stage in the next cycle. 
     When the piezoelectric element  10  is driven by duty, power consumption of the piezoelectric element  10  is reduced, and heat generated by the piezoelectric structure  12  is further reduced. 
     Wherein, the ratio of the duration of the first stage to the duration of the second stage is from 1:1 to 1:10. For example, the ratio of the duration of the first stage to the duration of the second stage is set as 2:1 or 3:1. 
     By reasonably setting the duration of the pulse signal in the second driving signal and the duration of the preset voltage, power consumption of the piezoelectric element  10  may be reduced without affecting the actual haptic effect of users, and heat generated by the piezoelectric structure  12  is further reduced. 
     In this embodiment of the disclosure, the opening penetrating through the piezoelectric structure is formed in the piezoelectric structure, such that the area of the piezoelectric structure in the piezoelectric element is decreased, the heating area is decreased when the piezoelectric structure vibrates, and heat generated by the piezoelectric structure is reduced, correspondingly; in addition, the heat conducting structure is additionally disposed in the piezoelectric element to dissipate heat generated when the piezoelectric structure vibrates, such that the heat-dissipation property of the piezoelectric element is improved, the problems that the piezoelectric structure is broken down and the resonance frequency of the piezoelectric structure is affected due to excessively high temperature of the piezoelectric element are solved, and the reliability of the piezoelectric structure is improved. 
     “One embodiment”, “an embodiment” or “one or more embodiments” in this specification means that specific features, structures, or characteristics described in conjunction with said embodiment are included in at least one embodiment of the disclosure. In addition, it should be noted that the expression “in one embodiment” does not definitely refer to the same embodiment. 
     A great plenty of specific details are provided in this specification. However, it can be understood that the embodiments of the disclosure can be implemented even without these specific details. In some embodiments, known methods, structures and techniques are not stated in detail to ensure that the understanding of this specification will not be obscured. 
     In the Claims, any reference marks should not be construed as limitations of the Claims. The term “comprise” shall not exclude the existence of elements or steps not listed in the Claims. “A/an” or “one” before an element shall not exclude the possibility of multiple said elements. The disclosure may be implemented by means of hardware comprising a plurality of different elements and a properly programmed computer. In a claim in which a plurality of devices are listed, several of these devices may be specifically implemented by means of the same hardware. Terms such as “first”, “second” and “third” do not indicate any order, and may be interpreted as names. 
     Finally, it should be noted that the above embodiments are merely used to explain the technical solutions of the disclosure, and are not intended to limit the disclosure. Although the disclosure has been explained in detail with reference to the above embodiments, those ordinarily skilled in the art would appreciate that the technical solutions recorded in these embodiments can still be amended or part of the technical features in these embodiments can be equivalently substituted without causing the essence of corresponding technical solutions to deviate from the spirit and scope of the technical solutions of these embodiments.