Ultrasonic transmitting device and preparation method thereof

Abstract

The invention discloses an ultrasonic transmitting device and a preparation method thereof. A vibration area of the ultrasonic transmitting device comprises a plurality of device rows, a plurality of ultrasonic transduction units are arranged in each device row at intervals in the first direction, the device rows are arranged in the second direction, and the ultrasonic transduction units in every two adjacent device rows are arranged in a staggered mode in the second direction. The preparation method comprises the following steps: providing a wafer; forming a bottom electrode layer on the surface of the wafer; forming a piezoelectric material layer on one side, far away from the wafer, of the bottom electrode layer; the piezoelectric material layers are located at the positions corresponding to the ultrasonic transduction units and the frame area. Forming a top electrode layer on one side, far away from the bottom electrode layer, of the piezoelectric material layer; wherein the top electrode layer is located at a position corresponding to each ultrasonic transduction unit; and patterning the bottom electrode layer and the wafer to form an ultrasonic transduction unit. According to the embodiment of the invention, the output capability of the ultrasonic transmitting device under the same unit area can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems, and in particular to an ultrasonic transmitting device and a preparation method thereof. Background Art

[0002] Piezoelectric Micromachined Ultrasonic Transducer (pMUT) based on Micro-Electro-Mechanical System (MEMS) technology is an important device that can be used in application fields such as robot obstacle avoidance, ultrasonic gesture recognition, ultrasonic under-screen fingerprint recognition, and ultrasonic imaging.

[0003] At present, most pMUT units adopt a circular design and are arranged in an array on a wafer to form a phased array pMUT ultrasonic module. However, the circular array is limited by its shape and there will be a large space loss when it is densely arranged, resulting in poor output capacity of the pMUT ultrasonic module under the same unit area. Summary of the invention

[0004] The present invention provides an ultrasonic emitting device and a preparation method thereof, so as to solve the problem that the output capacity of a pMUT ultrasonic module is relatively poor under the same unit area.

[0005] According to one aspect of the present invention, a method for preparing an ultrasonic emitting device is provided, wherein the ultrasonic emitting device comprises a vibration region and a frame region, wherein the frame region is arranged around the vibration region; the vibration region comprises a plurality of device rows, wherein a plurality of ultrasonic transducer units are arranged at intervals along a first direction in each of the device rows, wherein each of the device rows is arranged along a second direction, and wherein each of the ultrasonic transducer units in two adjacent device rows are arranged alternately in the second direction; wherein the first direction is perpendicular to the second direction;

[0006] The preparation method comprises:

[0007] providing a wafer;

[0008] forming a bottom electrode layer on the surface of the wafer;

[0009] A piezoelectric material layer is formed on a side of the bottom electrode layer away from the wafer; wherein the piezoelectric material layer is located at positions corresponding to each ultrasonic transducer unit and the frame area;

[0010] A top electrode layer is formed on a side of the piezoelectric material layer away from the bottom electrode layer; wherein the top electrode layer is located at a position corresponding to each ultrasonic transducer unit;

[0011] The bottom electrode layer and the wafer are patterned to form the ultrasonic transducer unit.

[0012] Optionally, the wafer includes a substrate layer, an insulating layer and a base layer which are stacked; wherein the substrate layer and the base layer are both made of silicon material, and the insulating layer is made of silicon dioxide material.

[0013] Optionally, patterning the bottom electrode layer and the wafer includes:

[0014] The bottom electrode layer is patterned by ion beam etching to form a first slit at a position of the bottom electrode layer corresponding to between adjacent ultrasonic transducer units;

[0015] The base layer is patterned by reactive ion etching to form a second slit at a position of the base layer corresponding to between adjacent ultrasonic transducer units; wherein the orthographic projection of the second slit on the wafer completely overlaps the orthographic projection of the first slit on the wafer.

[0016] Optionally, forming a piezoelectric material layer on a side of the bottom electrode layer away from the wafer includes:

[0017] Using a magnetron sputtering method, sputtering a piezoelectric film layer having a preset thickness on a side of the bottom electrode layer away from the wafer;

[0018] The piezoelectric film layer is patterned by wet etching or dry etching to form the piezoelectric material layer with a preset area.

[0019] Optionally, when the preset area remains unchanged, increasing the preset thickness is suitable for the ultrasonic emitting device with a higher resonance frequency;

[0020] When the preset thickness remains unchanged, reducing the preset area is suitable for the ultrasonic emitting device with a higher resonance frequency.

[0021] Optionally, forming a top electrode layer on a side of the piezoelectric material layer away from the bottom electrode layer includes:

[0022] Using a magnetron sputtering method, sputtering a top metal layer on a side of the piezoelectric material layer away from the bottom electrode layer;

[0023] The top metal layer is patterned by a metal stripping process or an ion beam etching method to retain the top metal layer located in the vibration area to form the top electrode layer.

[0024] Optionally, the thickness of the bottom electrode layer and the top electrode layer ranges from 150 to 250 nm;

[0025] The material of the bottom electrode layer includes any one of platinum, gold, silver, and aluminum, and the material of the top electrode layer includes any one of platinum, gold, silver, and aluminum.

[0026] Optionally, the method for preparing an ultrasonic emitting device further includes:

[0027] Thinning a side of the wafer away from the bottom electrode layer;

[0028] A support column is formed on a side of the wafer away from the bottom electrode layer; wherein the support column is located between two adjacent ultrasonic transducer units.

[0029] Optionally, forming a support column on a side of the wafer away from the bottom electrode layer includes:

[0030] Etching the substrate layer of the wafer by deep reactive ion etching to form a through hole penetrating the substrate layer;

[0031] A dry etching method is adopted to etch the insulating layer of the wafer at a position corresponding to the through hole, so that the remaining parts of the substrate layer and the insulating layer form the supporting column.

[0032] According to another aspect of the present invention, there is provided an ultrasonic emitting device, which is manufactured by the method for manufacturing an ultrasonic emitting device as described in any embodiment of the first aspect.

[0033] The method for preparing an ultrasonic emitting device provided in an embodiment of the present invention patterns the bottom electrode layer and the wafer by changing the shape of the bottom electrode layer exposed by the patterned piezoelectric material layer, thereby forming a quadrilateral-shaped ultrasonic transducer unit with four vertex corners of the quadrilateral recessed inward. Compared with the circular pMUT unit array arrangement in the related art, which will produce a large space loss, the quadrilateral-shaped dense arrangement formed in the embodiment of the present invention fully utilizes the area of ​​the vibration zone of the ultrasonic emitting device, thereby increasing the effective vibration area of ​​the ultrasonic transducer unit, and can effectively improve the output capacity of the ultrasonic emitting device under the same unit area.

[0034] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a schematic diagram of the arrangement structure of a pMUT unit provided by the prior art;

[0037] Figure 2 is a schematic diagram of a top view of an ultrasonic emitting device provided according to an embodiment of the present invention;

[0038] Figure 3 It is a schematic flow chart of a method for preparing an ultrasonic emitting device according to an embodiment of the present invention;

[0039] Figure 4 yes Figure 3 The corresponding edges of each step Figure 2 Schematic diagram of the cross-sectional structure along the A-A' direction;

[0040] Figure 5 is a schematic diagram of a specific flow chart of step S150 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention;

[0041] Figure 6 It is a specific flow chart of step S130 in a method for preparing an ultrasonic emitting device provided according to an embodiment of the present invention.

[0042] Figure 7 is a schematic diagram of a specific flow chart of step S140 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention;

[0043] Figure 8 is a schematic flow chart of another method for preparing an ultrasonic emitting device according to an embodiment of the present invention;

[0044] Fig. 9 yes Figure 8 Specific structural schematic diagram corresponding to each step in;

[0045] Fig.10 is a schematic diagram of a top view of a piezoelectric material layer formed in step S130 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention;

[0046] Fig.11 is a schematic diagram of a top view of the structure of a top electrode layer formed in step S140 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention;

[0047] Fig.12 yes Fig.10 and Fig.11 Schematic diagram of the overlapping top view structure;

[0048] Fig.13 is a schematic diagram of a top view of the structure of a bottom electrode layer and a wafer formed in step S150 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention;

[0049] Fig.14 yes Fig.10 , Fig.11 and Fig.13 Schematic diagram of the overlapping top view structure;

[0050] Fig.15 is a schematic diagram of a top view of a substrate layer and an insulating layer on the back side of a wafer provided in an embodiment of the present invention;

[0051] Fig.16 yes Fig.10 , Fig.11 , Fig.13 and Fig.15 Schematic diagram of the overlapping top view structure;

[0052] Fig.17 yes Figure 2 A schematic diagram of the enlarged structure of the dotted circle part. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0054] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0055] As described in the background technology, pMUT is an important device, and its structure usually includes a silicon substrate layer, a lower electrode layer, a piezoelectric film layer and an upper electrode layer, which together constitute the diaphragm of the device. The working principle of pMUT is related to the piezoelectric effect of the piezoelectric film layer. When the positive piezoelectric effect occurs, that is, the diaphragm receives sound waves, the ultrasonic wave causes the diaphragm to vibrate, and the deformation of the diaphragm is continuously generated up and down, and the piezoelectric film layer is periodically stretched or compressed, so that the piezoelectric film layer generates an electric charge, and is connected to the outside through the upper electrode and the lower electrode, and the external circuit can receive the changing charge signal. When the reverse piezoelectric effect occurs, the external circuit passes a high-frequency alternating voltage (such as a sine wave) to the upper electrode and the lower electrode, and the upper electrode and the lower electrode generate an alternating electric field in the piezoelectric film layer. The electric field causes the piezoelectric film layer to produce a tensile or compressed deformation, so that the piezoelectric film layer drives the diaphragm to vibrate and generate sound waves.

[0056] Recently, ultrasonic focusing and orientation, as an advanced technology, is gradually being widely used in various scenarios. Ultrasonic focusing refers to applying a driving signal with a preset phase difference to pMUT units at different positions in an array composed of pMUT devices, so that each pMUT unit will emit ultrasonic waves with different phase differences. Subsequently, due to the interference principle of ultrasonic waves, sound waves with superimposed intensities will be generated at the preset focal point, and sound waves with offset intensities will be generated in the rest of the parts. This technology is widely used in radar, ultrasonic imaging, ultrasonic audio, ultrasonic tactile sensing and other fields.

[0057] At present, most pMUT units are circular in design and arranged in an array on a wafer to form a phased array pMUT ultrasonic module. The pMUT phased array module usually requires multiple groups and a large number of pMUT ultrasonic units. However, the circular array is limited by its shape and there will be a large space loss when it is densely arranged. Figure 1 FIG. 1 is a schematic diagram of the arrangement structure of a pMUT unit provided by the prior art. Figure 1 As shown, the circular pMUT unit 01 is arranged in an array on the wafer 02. Due to the circular shape of the pMUT unit 01, there will be a large space loss when multiple pMUT units 01 are densely arranged. For example, the circular pMUT unit 01 is an effective diaphragm part, and there is a large area of ​​invalid part between two adjacent pMUT units 01 along the diagonal direction. The sound pressure level (SPL) of the emitted sound pressure can be calculated by formula (1), which can be expressed as follows:

[0058] SPL∝A·f·d(1)

[0059] Wherein, A represents the effective diaphragm area, f represents the signal frequency, and d represents the equivalent vibration displacement of the diaphragm at the signal frequency.

[0060] In summary, when other conditions are the same, the larger the effective vibration area, the stronger the output capacity of the ultrasonic transmitting module. However, when the circular pMUT units 01 are densely arranged, a large space loss is caused, resulting in a poor output capacity of the pMUT ultrasonic module under the same unit area.

[0061] Based on the above technical problems, the embodiments of the present invention propose the following technical solutions:

[0062] An embodiment of the present invention provides an ultrasonic transmitting device. Figure 2 FIG. 1 is a schematic diagram of a top view of an ultrasonic emitting device provided by an embodiment of the present invention. Figure 2 As shown, the ultrasonic emitting device includes a vibration area 100 and a frame area 200, and the frame area 200 is arranged around the vibration area 100; the vibration area 100 includes a plurality of device rows 101, and a plurality of ultrasonic transducer units 102 are arranged at intervals along a first direction in each device row 101, and each device row 101 is arranged along a second direction, and each ultrasonic transducer unit 102 in two adjacent device rows 101 is arranged alternately in the second direction; wherein the first direction is perpendicular to the second direction.

[0063] Specifically, Figure 2 The top view of the front side of the ultrasonic emitting device is shown in FIG. Figure 2 , the central area of ​​the ultrasonic emitting device is the vibration area 100, and the edge area around the central area is the frame area 200. The vibration area 100 is the main vibration functional area of ​​the ultrasonic emitting device, and the frame area 200 is the area used for support of the ultrasonic emitting device. Since the ultrasonic emitting device includes a plurality of ultrasonic transducer units 102, and the plurality of ultrasonic transducer units 102 are arranged in an array of a specific shape, a plurality of device rows 101 are arranged in the vibration area 100, and the device rows 101 extend along the first direction, and each device row 101 is densely arranged in parallel along the second direction. Among them, the first direction and the second direction are perpendicular to each other. For example, the first direction can be the X direction, and the second direction is the Y direction; or, the first direction can be the Y direction, and the second direction is the X direction, which is not limited here. In the embodiments of the present invention, the first direction is the X direction and the second direction is the Y direction as an example for explanation.

[0064] A plurality of ultrasonic transducer units 102 arranged at intervals are provided in each device row 101, and a support column 103 is provided between two adjacent ultrasonic transducer units 102. One support column 103 can be shared by two ultrasonic transducer units 102, and is used to support two adjacent ultrasonic transducer units 102 in the same device row 101. In other words, the area where each support column 103 in the vibration area 100 is located is an invalid area. In two adjacent device rows 101, each ultrasonic transducer unit 102 in each device row 101 is staggered in the second direction, that is, in the second direction, each column also includes a plurality of ultrasonic transducer units 102 arranged at intervals, and a support column 103 is also included between two adjacent ultrasonic transducer units 102 in the second direction, and the arrangement is a honeycomb-like structure. Furthermore, the overall shape of each ultrasonic transducer unit 102 can be designed to be a quadrilateral with four vertices concave inwardly, so that when arranged in the above-mentioned honeycomb-like structure, a dense arrangement effect can be achieved, effectively reducing the space loss of the ultrasonic emitting device, increasing the effective vibration area, and helping to improve the output capacity of the ultrasonic emitting device under the same unit area.

[0065] An embodiment of the present invention provides a method for preparing an ultrasonic emitting device. Figure 3 is a flow chart of a method for preparing an ultrasonic emitting device provided by an embodiment of the present invention, Figure 4 yes Figure 3 The corresponding edges of each step Figure 2 Schematic diagram of the cross-sectional structure along the A-A' direction. Figure 3 and Figure 4 The method for preparing the ultrasonic emitting device specifically comprises the following steps:

[0066] S110 , providing a wafer 10 .

[0067] Exemplarily, the wafer includes a stacked substrate layer, an insulating layer and a base layer; wherein the substrate layer and the base layer are both made of silicon material, and the insulating layer is made of silicon dioxide material. Specifically, a wafer with a silicon layer on an insulating substrate, i.e., an SOI (Silicon-On-Insulator) wafer, is used. The SOI wafer includes a stacked substrate silicon layer, a silicon dioxide layer and a device silicon layer.

[0068] S120 , forming a bottom electrode layer 20 on the surface of the wafer 10 .

[0069] Specifically, a magnetron sputtering method is used to sputter a metal material on the surface of the wafer to form a bottom electrode layer that covers the entire surface of the wafer.

[0070] S130 , forming a piezoelectric material layer 30 on a side of the bottom electrode layer 20 away from the wafer 10 ; wherein the piezoelectric material layer 30 is located at positions corresponding to each ultrasonic transducer unit and the frame area.

[0071] Specifically, a piezoelectric material layer corresponding to each ultrasonic transducer unit and the frame area in the ultrasonic emitting device structure is formed on the surface of the bottom electrode layer. The piezoelectric material layer corresponding to each ultrasonic transducer unit forms a part of the diaphragm, which is an effective vibration area; the piezoelectric material layer corresponding to the frame area is an invalid area. Exemplarily, the material of the piezoelectric material layer can be lead zirconate titanate.

[0072] S140 , forming a top electrode layer 40 on a side of the piezoelectric material layer 30 away from the bottom electrode layer 20 ; wherein the top electrode layer 40 is located at a position corresponding to each ultrasonic transducer unit.

[0073] S150 , patterning the bottom electrode layer 20 and the wafer 10 to form an ultrasonic transducer unit.

[0074] Specifically, the bottom electrode layer and the wafer are patterned to divide the bottom electrode layer and the wafer according to each ultrasonic transducer unit. The top electrode layer cooperates with the bottom electrode layer to receive a driving signal that acts on the piezoelectric material layer corresponding to each ultrasonic transducer unit.

[0075] Based on the patterned piezoelectric material layer formed by the above method, the bottom electrode layer and the wafer are patterned according to the shape of the bottom electrode layer exposed by the pattern of the piezoelectric material layer to form Figure 2 The ultrasonic transducer unit 102 shown in the figure has a quadrilateral shape with four inwardly concave vertices. Compared with the circular pMUT units in the related art, which have a large space loss when arranged in an array, each ultrasonic transducer unit in the ultrasonic transmitting device formed by the preparation method of the embodiment of the present invention has a quadrilateral shape and is arranged according to Figure 2 The arrangement shown in the figure is densely arranged, which can make full use of the area of ​​the vibration area 100 of the ultrasonic emitting device and increase the effective vibration area of ​​the ultrasonic transducer unit, thereby effectively improving the output capacity of the ultrasonic emitting device under the same unit area.

[0076] The method for preparing an ultrasonic emitting device provided in an embodiment of the present invention patterns the bottom electrode layer and the wafer by changing the shape of the bottom electrode layer exposed by the patterned piezoelectric material layer, thereby forming a quadrilateral-shaped ultrasonic transducer unit with four vertex corners of the quadrilateral recessed inward. Compared with the circular pMUT unit array arrangement in the related art, which will produce a large space loss, the quadrilateral-shaped dense arrangement formed in the embodiment of the present invention fully utilizes the area of ​​the vibration zone of the ultrasonic emitting device, thereby increasing the effective vibration area of ​​the ultrasonic transducer unit, and can effectively improve the output capacity of the ultrasonic emitting device under the same unit area.

[0077] Optionally, Figure 5FIG. 1 is a schematic diagram of a specific flow chart of step S150 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention. Figure 5 As shown, the bottom electrode layer and the wafer are patterned in step S150, including the following steps:

[0078] S151, patterning the bottom electrode layer by using an ion beam etching method to form a first slit at a position of the bottom electrode layer corresponding to between adjacent ultrasonic transducer units.

[0079] Specifically, the ion beam etching (IBE) method uses the glow discharge principle to decompose argon gas into argon ions, which are accelerated by the anode electric field to physically bombard the sample surface to achieve the etching effect. The IBE etching method is used to etch the bottom electrode layer to achieve patterning, thereby forming a pattern on the bottom electrode layer that corresponds to the patterned piezoelectric material layer, so that a first slit is formed at a position corresponding to the gap between two adjacent ultrasonic transducer units, so as to divide the metal layer set on the entire surface into bottom electrode layers that correspond to the piezoelectric material layers of each ultrasonic transducer unit.

[0080] S152, patterning the base layer using reactive ion etching to form a second slit at a position of the base layer corresponding to between adjacent ultrasonic transducer units; wherein the orthographic projection of the second slit on the wafer completely overlaps with the orthographic projection of the first slit on the wafer.

[0081] Specifically, the reactive ion etching (RIE) method uses an ion beam of a reactive gas to cut the chemical bonds of the protective film material, so that it produces low-molecular substances, which volatilize or free the board surface to achieve the etching effect. The RIE etching method is used to etch the base layer to achieve patterning, thereby forming a pattern corresponding to the piezoelectric material layer on the base layer, so that a second slit is formed at a position corresponding to the gap between two adjacent ultrasonic transducer units, and the width of the second slit is equal to that of the first slit, that is, the orthographic projection of the second slit on the wafer completely overlaps with the orthographic projection of the first slit on the wafer, thereby dividing the device silicon layer in the entire wafer into base layers corresponding to the piezoelectric material layers of each ultrasonic transducer unit. It should be noted that the widths of the first slit and the second slit can be set to a size that can be satisfied by the etching accuracy according to the etching accuracy of the corresponding etching method, and are not limited here.

[0082] Optionally, Figure 6 FIG. 1 is a schematic diagram of a specific flow chart of step S130 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention. Figure 6As shown, forming a piezoelectric material layer on a side of the bottom electrode layer away from the wafer in step S130 specifically includes the following steps:

[0083] S131. Using a magnetron sputtering method, a piezoelectric film layer having a preset thickness is sputtered on a side of the bottom electrode layer away from the wafer.

[0084] Specifically, a magnetron sputtering method and lead zirconate titanate piezoelectric material are used to sputter a piezoelectric film layer that is disposed on the entire surface and has a preset thickness on the surface of the bottom electrode layer.

[0085] S132, patterning the piezoelectric film layer by wet etching or dry etching to form a piezoelectric material layer with a preset area.

[0086] Specifically, a wet etching method or a dry etching method is used to etch the piezoelectric film layer to achieve patterning, thereby forming a discrete piezoelectric material layer with a certain preset area. The preset thickness and preset area of ​​the piezoelectric material layer are related to the resonant frequency of the prepared ultrasonic emitting device, and can be set by the user according to the actual resonant frequency requirements, and are not limited here. For example, when the preset area remains unchanged, increasing the preset thickness is suitable for ultrasonic emitting devices with higher resonant frequencies; when the preset thickness remains unchanged, reducing the preset area is suitable for ultrasonic emitting devices with higher resonant frequencies.

[0087] Optionally, Figure 7 FIG. 1 is a schematic diagram of a specific flow chart of step S140 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention. Figure 7 As shown, forming a top electrode layer on a side of the piezoelectric material layer away from the bottom electrode layer in step S140 specifically includes the following steps:

[0088] S141. Using a magnetron sputtering method, sputtering is performed on a side of the piezoelectric material layer away from the bottom electrode layer to form a top metal layer.

[0089] Specifically, a magnetron sputtering method and corresponding metal materials are used to sputter a top metal layer disposed on the entire surface of the piezoelectric material layer.

[0090] S142. Patterning the top metal layer by using a metal stripping process or an ion beam etching method to retain the top metal layer in the vibration area to form a top electrode layer.

[0091] Specifically, a metal lift-off process or an IBE etching method is used to etch the top metal layer to achieve patterning, thereby retaining the top metal layer corresponding to the piezoelectric material layer located in the vibration area to form a top electrode layer. Exemplarily, the thickness range of the bottom electrode layer and the top electrode layer includes 150 to 250nm; the material of the bottom electrode layer includes any one of platinum, gold, silver, and aluminum, and the material of the top electrode layer includes any one of platinum, gold, silver, and aluminum. For example: In an embodiment of the present invention, gold may be used for the top electrode layer, and platinum may be used for the bottom electrode layer. The thickness of the top electrode layer and the bottom electrode layer is preferably 200nm, which can maintain good electrical contact and reduce the preparation cost to a certain extent.

[0092] Optionally, Figure 8 is a flow chart of another method for preparing an ultrasonic emitting device provided by an embodiment of the present invention, Fig. 9 yes Figure 8 Specific structural diagram corresponding to each step in the above embodiments. Figure 8 and Fig. 9 The method for preparing the ultrasonic emitting device specifically comprises the following steps:

[0093] S210 , providing a wafer 10 .

[0094] S220 , forming a bottom electrode layer 20 on the surface of the wafer 10 .

[0095] S230 , forming a piezoelectric material layer 30 on a side of the bottom electrode layer 20 away from the wafer 10 ; wherein the piezoelectric material layer 30 is located at positions corresponding to each ultrasonic transducer unit and the frame area.

[0096] S240 , forming a top electrode layer 40 on a side of the piezoelectric material layer 30 away from the bottom electrode layer 20 ; wherein the top electrode layer 40 is located at a position corresponding to each ultrasonic transducer unit.

[0097] S250 , patterning the bottom electrode layer 20 and the wafer 10 to form an ultrasonic transducer unit.

[0098] S260 , thinning the side of the wafer 10 away from the bottom electrode layer 20 .

[0099] Specifically, the back side of the wafer 10 is thinned by using a chemical mechanical polishing (CMP) method.

[0100] S270 , forming a support column 103 on a side of the wafer 10 away from the bottom electrode layer 20 ; wherein the support column 103 is located between two adjacent ultrasonic transducer units.

[0101] Exemplarily, a deep reactive ion etching (DRIE) method is used to etch the substrate layer of the wafer to form a through hole penetrating the substrate layer. At the position corresponding to each ultrasonic transducer unit, the substrate silicon layer of the wafer is deep silicon etched to form a through hole penetrating the thicker substrate silicon layer.

[0102] The insulating layer of the wafer is etched at the position corresponding to the through hole by dry etching, so that the substrate layer and the remaining part of the insulating layer form a support column. For the thinner silicon dioxide layer in the wafer, the dry etching method is used to etch at the position corresponding to the through hole on the substrate silicon layer, so that the device silicon layer is exposed at the through hole position on the back of the wafer, and a support column is formed on the substrate silicon layer and the insulating layer of the wafer at the position corresponding to the position between two adjacent ultrasonic transducer units. Between the two adjacent support columns is the through hole formed on the substrate silicon layer and the insulating layer, that is, a cavity is formed directly below the ultrasonic transducer unit, releasing the diaphragm structure that can vibrate effectively, so that the diaphragm structure can achieve up and down reciprocating vibration.

[0103] A possible implementation example, Fig.10 is a schematic diagram of a top view of the structure of a piezoelectric material layer formed in step S130 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention; Fig.11 is a schematic diagram of a top view of the structure of a top electrode layer formed in step S140 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention; Fig.12 yes Fig.10 and Fig.11 Schematic diagram of the overlapping top view structure;

[0104] Fig.13 It is a schematic diagram of a top view of a bottom electrode layer and a wafer formed in step S150 in a method for preparing an ultrasonic emitting device provided in an embodiment of the present invention; Fig.14 yes Fig.10 , Fig.11 and Fig.13 Schematic diagram of the overlapping top view structure; Fig.15 is a schematic diagram of a top view of the substrate layer and the insulating layer on the back side of a wafer provided by an embodiment of the present invention; Fig.16 yes Fig.10 , Fig.11 , Fig.13 and Fig.15 Schematic diagram of the overlapping top view structure. Fig.10 The pattern in the figure is the part of the piezoelectric film layer that needs to be etched away. Fig.11 The pattern in is the portion reserved for the top electrode layer 40. Fig.13 The pattern in FIG. 1 is the metal layer of the bottom electrode and the device silicon layer of the wafer 10 that need to be etched away. Fig.15The pattern in FIG. 1 is the part of the substrate layer and the insulating layer of the wafer 10 that needs to be etched away. Fig.12 , Fig.14 and Fig.16 In the top view structure after the layers overlap, the top electrode layer 40 and the piezoelectric material layer 30 are rectangular, and the area of ​​the bottom electrode layer 20 exceeds the area of ​​the top electrode layer 40 or the piezoelectric material layer 30, that is, the orthographic projection of the bottom electrode layer 20 on the wafer 10 is a quadrilateral-like shape with four vertex corners of the quadrilateral concave inward, and the rectangular orthographic projection of the top electrode layer 40 on the wafer 10 is located at the center of the orthographic projection of the bottom electrode layer 20. The shape of the ultrasonic transducer unit is designed in this way, so that the ultrasonic transducer units can be densely arranged, the space of the ultrasonic emitting device is fully utilized, the space loss is reduced, the effective vibration area is increased, and it is beneficial to improve the output capacity of the ultrasonic emitting device under the same unit area.

[0105] The embodiment of the present invention further provides an ultrasonic emitting device. The ultrasonic emitting device is prepared by using the ultrasonic emitting device preparation method provided by any embodiment of the present invention, and has similar beneficial effects.

[0106] For example, Fig.17 yes Figure 2 An enlarged structural diagram of the dotted circle portion in FIG. Fig.17 As shown, the bottom electrode layer 20 of each ultrasonic transducer unit 102 includes a main body 21, first extensions 22 located at both sides of the main body 21 along a first direction, and second extensions 23 located at both sides of the main body 21 along a second direction.

[0107] The first extension portion 21 and the second extension portion 23 form a corner portion 24 at a position corresponding to the top corner of the top electrode layer 40; the corner portion 24 is a right angle, and along the diagonal direction of the top electrode layer 40, the two corner portions 24 corresponding to two adjacent ultrasonic transducer units 102 are arranged in an embedded manner.

[0108] Specifically, the bottom electrode layer 20 may also include a main body 21 and a first extension 22 and a second extension 23 surrounding the main body 21, wherein the length of the first extension 22 is equal to the width of the top electrode layer 40, and the length of the second extension 23 is equal to the length of the top electrode layer 40. Such an arrangement allows the first extension 21 and the second extension 23 to form a corner portion 24 at each vertex position corresponding to the top electrode layer 40, and the corner portion 24 is at a right angle, so that each ultrasonic transducer unit 102 formed is in the shape of a quadrilateral with four vertex corners of the quadrilateral concave inward. Designing the ultrasonic transducer unit 102 to be in the shape of a quadrilateral, the adjacent two ultrasonic transducer units 102 along the diagonal direction in the adjacent two device rows 101 can be arranged in a chimeric arrangement at the corner portion 24, so as to realize the dense arrangement of each ultrasonic transducer unit 102, which can further increase the effective vibration area, thereby effectively improving the output capacity of the ultrasonic emitting device.

[0109] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an ultrasonic emitting device, characterized in that: The ultrasonic emitting device comprises a vibration area and a frame area, wherein the frame area is arranged around the vibration area; the vibration area comprises a plurality of device rows, wherein a plurality of ultrasonic transducer units are arranged at intervals along a first direction in each of the device rows, wherein each of the device rows is arranged along a second direction, and wherein each of the ultrasonic transducer units in two adjacent device rows are arranged alternately in the second direction; wherein the first direction is perpendicular to the second direction; The preparation method comprises: providing a wafer; forming a bottom electrode layer on the surface of the wafer; A piezoelectric material layer is formed on a side of the bottom electrode layer away from the wafer; wherein the piezoelectric material layer is located at positions corresponding to each ultrasonic transducer unit and the frame area; A top electrode layer is formed on a side of the piezoelectric material layer away from the bottom electrode layer; wherein the top electrode layer is located at a position corresponding to each ultrasonic transducer unit; The bottom electrode layer and the wafer are patterned to form the ultrasonic transducer unit.

2. The method for preparing an ultrasonic emitting device according to claim 1, characterized in that: The wafer comprises a substrate layer, an insulating layer and a base layer which are stacked; wherein the substrate layer and the base layer are both made of silicon material, and the insulating layer is made of silicon dioxide material.

3. The method for preparing an ultrasonic emitting device according to claim 2, characterized in that: The patterning of the bottom electrode layer and the wafer comprises: The bottom electrode layer is patterned by ion beam etching to form a first slit at a position of the bottom electrode layer corresponding to between adjacent ultrasonic transducer units; The base layer is patterned by reactive ion etching to form a second slit at a position of the base layer corresponding to between adjacent ultrasonic transducer units; wherein the orthographic projection of the second slit on the wafer completely overlaps the orthographic projection of the first slit on the wafer.

4. The method for preparing an ultrasonic emitting device according to claim 1, characterized in that: The step of forming a piezoelectric material layer on a side of the bottom electrode layer away from the wafer comprises: Using a magnetron sputtering method, sputtering a piezoelectric film layer having a preset thickness on a side of the bottom electrode layer away from the wafer; The piezoelectric film layer is patterned by wet etching or dry etching to form the piezoelectric material layer with a preset area.

5. The method for preparing an ultrasonic emitting device according to claim 4, characterized in that: When the preset area remains unchanged, increasing the preset thickness is suitable for the ultrasonic emitting device with a higher resonance frequency; When the preset thickness remains unchanged, reducing the preset area is suitable for the ultrasonic emitting device with a higher resonance frequency.

6. The method for preparing an ultrasonic emitting device according to claim 1, characterized in that: The forming of a top electrode layer on a side of the piezoelectric material layer away from the bottom electrode layer comprises: Using a magnetron sputtering method, sputtering a top metal layer on a side of the piezoelectric material layer away from the bottom electrode layer; The top metal layer is patterned by a metal stripping process or an ion beam etching method to retain the top metal layer located in the vibration area to form the top electrode layer.

7. The method for preparing an ultrasonic emitting device according to claim 1, characterized in that: The thickness of the bottom electrode layer and the top electrode layer ranges from 150 to 250 nm; The material of the bottom electrode layer includes any one of platinum, gold, silver, and aluminum, and the material of the top electrode layer includes any one of platinum, gold, silver, and aluminum.

8. The method for preparing an ultrasonic emitting device according to claim 2, characterized in that: Also includes: Thinning a side of the wafer away from the bottom electrode layer; A support column is formed on a side of the wafer away from the bottom electrode layer; wherein the support column is located between two adjacent ultrasonic transducer units.

9. The method for preparing an ultrasonic emitting device according to claim 8, characterized in that: The step of forming a support column on a side of the wafer away from the bottom electrode layer comprises: Etching the substrate layer of the wafer by deep reactive ion etching to form a through hole penetrating the substrate layer; A dry etching method is adopted to etch the insulating layer of the wafer at a position corresponding to the through hole, so that the remaining parts of the substrate layer and the insulating layer form the supporting column.

10. An ultrasonic transmitting device, characterized in that: The ultrasonic emitting device is prepared by the method for preparing the ultrasonic emitting device according to any one of claims 1 to 9.

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