TWI747362B - Piezoelectric micromachined ultrasonic transducer and method of fabricating the same - Google Patents

Abstract

A piezoelectric micromachined ultrasonic transducer (PMUT) includes a substrate, a stopper, and a membrane, where the substrate and the stopper are composed of same material. The substrate has a cavity penetrating the substrate, and the stopper protrudes from a top surface of the substrate and surrounds the edge of the cavity. The membrane is disposed over the cavity and attached to the stopper.

Description

Piezoelectric micromechanical ultrasonic transducer and manufacturing method thereof

The present disclosure relates to the technical field of Micro Electro Mechanical System (MEMS), and particularly relates to a piezoelectric micro mechanical ultrasonic transducer (PMUT) and a manufacturing method thereof.

In the past few decades, Micro Machined Transducers (MUTs) have been extensively studied and have become an important component of various consumer electronics products, such as fingerprint sensors and proximity (proximity) sensing. Component parts of the device and gesture sensor. Generally speaking, MUTs can be divided into two categories, such as capacitive micromachined ultrasonic transducers (CMUTs) and piezoelectric micromachined ultrasonic transducers (PMUTs). For a typical piezoelectric micromechanical ultrasonic transducer, the piezoelectric micromechanical ultrasonic transducer includes a film layer composed of elastic materials, electrodes, and piezoelectric materials. This film layer is set on the acoustic resonator. On the cavity, to improve the acoustic performance of the piezoelectric micromachined ultrasonic transducer. During the operation of the piezoelectric micro-machined ultrasonic transducer, the ultrasonic waves generated by the vibration of the film will be transmitted from the piezoelectric micro-machined ultrasonic transducer to the target, and then the piezoelectric micro-machined ultrasonic transducer can Detect the reflected sound waves produced by ultrasonic waves hitting the target.

Generally, the piezoelectric micromachined ultrasonic transducer will operate at the bending resonance frequency of the film. The bending resonance frequency can be determined by selecting the correct material, the size and thickness of the film. Therefore, a good match of the resonance frequency of a single piezoelectric micromachined ultrasonic transducer is a necessary condition for normal operation. Pieces. However, since the cavity under the film layer is usually formed by etching the back surface of the substrate, a cavity opening is formed on the front surface of the substrate to define the size of the film layer. The size of the cavity opening may vary greatly in different regions within the same wafer or between different wafers, which inevitably leads to the variation of the resonance frequency of various piezoelectric micromachined ultrasonic transducers.

Therefore, there is a need to provide an improved piezoelectric micromechanical ultrasonic transducer and a manufacturing method thereof, so that the film layer size in the piezoelectric micromechanical ultrasonic transducer can be accurately controlled.

In view of this, in order to improve the uniformity of the resonance frequency of the piezoelectric micromachined ultrasonic transducer, it is necessary to propose an improved piezoelectric micromachined ultrasonic transducer and a manufacturing method thereof.

According to an embodiment of the present disclosure, the piezoelectric micromachined ultrasonic transducer includes a substrate, a barrier structure and a film layer, wherein the substrate and the barrier structure are composed of the same material. The base includes a cavity penetrating the base, and the blocking structure protrudes from the top surface of the base and surrounds the edge of the cavity. The film layer is arranged on the cavity and attached to the barrier structure.

According to another embodiment of the present disclosure, a method for manufacturing a piezoelectric micromechanical ultrasonic transducer is disclosed, which includes the following steps. The substrate is first etched to form a barrier structure protruding from the substrate, and then a sacrificial layer is formed on the substrate, wherein the barrier structure is exposed from the sacrificial layer. Then, a film layer is formed on the barrier structure and the sacrificial layer. Then, a cavity penetrating the substrate is formed to expose a part of the sacrificial layer. Subsequently, a part of the sacrificial layer exposed to the cavity is removed by using the barrier structure as an etch stop structure.

According to the above-mentioned embodiment of the present disclosure, the barrier structure is a structure protruding from the top surface of the substrate, and the size of the film layer can be adjusted by controlling the position of the barrier structure. Since the barrier structure is formed by etching the substrate, the barrier structure can not only be tightly attached to the substrate without peeling off from the substrate, but can also have vertical sidewalls. Through the above, the piezoelectric micro-machined ultrasonic transducer can be effectively improved Reliability and electrical performance.

100: Piezoelectric micromachined ultrasonic transducer

102: Base

102s: top surface

10) 4: Blocking structure

104s: top surface

106: Membrane

108: The main part

110: base

112: Truncated part

114: first contact pad

116: second contact pad

120: Cavity

120e: Edge

122: Part One

122s: top surface

124: Part Two

124s: top surface

126: Sacrifice Layer

130: grassroots

132: Dielectric layer

134: bottom conductive layer

136: Piezo Layer

138: Top conductive layer

140: passivation layer

152: truncated part

200: method

202: step

204: Step

206: Step

208: Step

210: Step

212: Step

D: distance

O: opening

In order to make the following easier to understand, the drawings and detailed text descriptions can be referred to when reading this disclosure. Through the specific embodiments in this text and with reference to the corresponding drawings, the specific embodiments of the present disclosure are explained in detail, and the principles of the specific embodiments of the present disclosure are explained. In addition, for the sake of clarity, the features in the drawings may not be drawn according to the actual scale, so the size of some features in some drawings may be deliberately enlarged or reduced.

FIG. 1 is a schematic top view of a piezoelectric micromachined ultrasonic transducer (PMUT) according to an embodiment of the disclosure.

FIG. 2 is a schematic cross-sectional view taken along the line AA′ in FIG. 1 according to an embodiment of the present disclosure.

FIG. 3 is a schematic diagram after a barrier structure is formed on a substrate according to an embodiment of the disclosure.

FIG. 4 is a schematic cross-sectional view after a sacrificial layer is formed on a substrate according to an embodiment of the disclosure.

FIG. 5 is a schematic cross-sectional view after forming a base layer on the barrier structure and the sacrificial layer according to an embodiment of the disclosure.

FIG. 6 is a schematic cross-sectional view after forming a stacked layer on a base layer to form a film layer according to an embodiment of the disclosure.

FIG. 7 is a schematic cross-sectional view after forming a contact pad according to an embodiment of the disclosure.

FIG. 8 is a schematic cross-sectional view after a cut-off portion is formed in the film according to an embodiment of the disclosure.

Figure 9 is a cross-sectional view after a cavity penetrating the substrate is formed according to an embodiment of the disclosure intention.

FIG. 10 is a flowchart of a method for manufacturing a piezoelectric micromachined ultrasonic transducer according to an embodiment of the disclosure.

The present disclosure provides several different embodiments, which can be used to implement different features of the present disclosure. To simplify the description, this disclosure also describes examples of specific components and settings. The purpose of providing these embodiments is only for illustration, and not for any limitation. For example, the following description of "the first feature is formed on or above the second feature" can mean "the first feature is in direct contact with the second feature", or it can mean "the first feature is in direct contact with the second feature". There are other features among the features", so that the first feature and the second feature are not in direct contact. In addition, various embodiments in the present disclosure may use repeated reference symbols and/or text annotations. These repeated reference symbols and notes are used to make the description more concise and clear, rather than to indicate the relevance between different embodiments and/or configurations.

In addition, regarding the space-related narrative vocabulary mentioned in this disclosure, such as: "below", "low", "below", "above", "above", "below", "top" ", "base" and similar words, for ease of description, their usage is to describe the relative relationship between one element or feature and another (or more) elements or features in the drawing. In addition to the swing outward shown in the diagram, these spatially related words are also used to describe the possible swing directions of the semiconductor device during use and operation. As the swing direction of the semiconductor device is different (rotated by 90 degrees or other orientations), the space-related narrative used to describe its swing direction should also be explained in a similar way.

Although the present disclosure uses terms such as first, second, and third to describe various elements, components, regions, layers, and/or sections, it should be understood that these elements, components, regions, layers, And/or blocks should not be restricted by these terms. These terms are only used to distinguish a certain element, component, region, layer, and/or block from another element, component, region, layer, and/or block, and do not mean and It means that the component has any previous ordinal number, and does not represent the order of arrangement of a certain component and another component, or the order of the manufacturing method. Therefore, without departing from the scope of the specific embodiments of the present disclosure, the first element, component, region, layer, or block discussed below can also be referred to as the second element, component, region, layer, or block Of.

The term "about" or "substantially" mentioned in this disclosure usually means within 20% of a given value or range, preferably within 10%, and more preferably within 5%, or Within 3%, or within 2%, or within 1%, or within 0.5%. It should be noted that the quantity provided in the manual is approximate, that is, the meaning of "approximate" or "substantial" can still be implied when there is no specific description of "approximate" or "substantial".

The specific sequence or level of the flowchart blocks disclosed in the process/flow chart below can be understood as an exemplary description. It is understandable that, according to different design preferences, the specific order or hierarchy of the flowchart blocks disclosed in this process/flow chart can be rearranged. In addition, part of the flowchart blocks can be combined or omitted. The attached method request items show the elements in each flowchart block in the order of examples, but this does not mean that the method request items are limited to this specific order or level.

Although specific embodiments are used below to describe the invention of the present disclosure, the principles of the invention of the present disclosure can also be applied to other embodiments. In addition, in order not to make the spirit of this disclosure obscure, specific details will be omitted, and the omitted details belong to the scope of knowledge of ordinary knowledgeable persons in the technical field.

FIG. 1 is a schematic top view of a piezoelectric micromachined ultrasonic transducer (PMUT) according to an embodiment of the disclosure. Referring to FIG. 1, the piezoelectric micromachined ultrasonic transducer 100 at least includes a substrate 102, a blocking structure 104, a film layer 106, a cut-off portion 112, a first contact pad 114 and a second contact pad 116. According to an embodiment of the present disclosure, the barrier structure 104 may be a ring-shaped structure protruding from the top surface of the substrate 102 so that a part of the film layer 106 may be attached to the barrier structure 104. The shape of the barrier structure 104 is not limited to this, and the barrier structure 104 may be a polygonal or arc shape arranged along the edge of the film layer 106. The film 106 can be wrapped It includes a main body portion 108 disposed above the cavity (not shown) and a base portion 110 disposed on the periphery of the main body portion 108. The shape of the main body portion 108 may be defined by the shape of the cut-off portion 112, and may be any shape, such as a circle, a fan shape, or a polygon. The blocking structure 104 may be provided along the periphery of the cut-off portion 112 and the periphery of the main body portion 108. The main body portion 108 of the film layer 106 may be a multilayer structure including electrodes and piezoelectric materials. The base 110 is attached to the barrier structure 104 and can be regarded as a portion extending from the main body portion 108 of the film layer 106. The first contact pad 114 and the second contact pad 116 may be disposed on opposite sides of the film layer 106, which may be electrically coupled to electrodes of the film layer 106, respectively. In addition, in order to avoid unexpected parasitic capacitance between the first contact pad 114 and the second contact pad 116, the size of the first contact pad 114 and the second contact pad 116 can be reduced as much as possible, but is not limited thereto. According to an embodiment of the present disclosure, the first contact pad 114 and the second contact pad 116 can be arranged on the same side of the film layer 106 or at any position, as long as the first contact pad 114 and the second contact pad 116 can be electrically coupled to the film layer 106. 106 electrodes are sufficient. Conductive traces (not shown) electrically coupled to the first contact pad 114 and the second contact pad 116 may be additionally provided on the substrate 102 in order to transmit electrical signals to or from the film layer 106 . During the operation of the piezoelectric micromachined ultrasonic transducer 100, when sound waves apply sound pressure to the film layer 106 or an electrical signal is applied to the film layer 106, the film layer 106, especially the main part 108 of the film layer 106, can vibration. By using the barrier structure 104, the size and position of the film layer 106 can be precisely and independently defined, regardless of the size and position of the cavity under the film layer 106. Therefore, the uniformity of the resonance frequency of each piezoelectric micromachined ultrasonic transducer 100 can be effectively improved.

FIG. 2 is a schematic cross-sectional view taken along the line AA′ of FIG. 1 according to an embodiment of the present disclosure. Referring to FIG. 2, the blocking structure 104 may protrude from the top surface 102 s of the substrate 102. The substrate 102 may be a semiconductor substrate, such as a bulk silicon substrate, but is not limited thereto. The substrate 102 and the barrier structure 104 may be composed of the same material, such as monocrystalline silicon, polycrystalline silicon, amorphous silicon, glass, ceramic materials, or other suitable materials. According to an embodiment of the present disclosure, the substrate 102 may be an SOI substrate. The composition of the sacrificial layer 126 is different from the composition of the substrate 102, the barrier structure 104 is disposed on the substrate 102, and the sacrificial layer 126 surrounds the barrier structure 104. According to an embodiment of the present disclosure, when the substrate 102 and/or the barrier structure 104 are composed of a semiconductor material (such as Si), the sacrificial layer 126 may be a dielectric layer, such as silicon _{oxide (SiO x} ) or dioxide Silicon (SiO ₂ ). In addition, the top surface of the sacrificial layer 126 may be substantially flush with the top surface of the barrier structure 104, so that the layers disposed on the sacrificial layer 126 and the barrier structure 104 may have a flat bottom surface. Referring to FIG. 2, although the width of the barrier structure 104 is much smaller than the width of the sacrificial layer 126, according to another embodiment of the present disclosure, the width of the barrier structure 104 may be designed to be greater than the width of the sacrificial layer 126. In addition, according to another embodiment of the present disclosure, when the width of the barrier structure 104 is sufficiently large, most of the sacrificial layer 126 can be replaced with the barrier structure 104. The stacked layer may include a base layer 130, a dielectric layer 132, a bottom conductive layer 134, a piezoelectric layer 136, a top conductive layer 138, and a passivation layer 140 sequentially disposed on the substrate 102. Part of the stacked layer may be disposed on the cavity 120. The edge 120e of the cavity 120 is adjacent to the stacked layer, and the blocking structure 104 may surround the edge 120e of the cavity 120. Therefore, the stacked layer disposed on the cavity 120 may constitute the film layer 106. In addition, the film layer 106 can be penetrated by the cut-off portion 112, thereby releasing the stress in the stacked layer. Specifically, the base layer 130 of the film layer 106 can have the required elasticity, so when sound waves or electrical signals act on the film layer 106, the film layer 106 can vibrate at a certain frequency. The bottom conductive layer 134 and the top conductive layer 138 of the film layer 106 may be electrically coupled to the first contact pad 114 and the second contact pad 116, respectively. It should be noted that the mechanical behavior of the film layer 106 is mainly determined by the base layer 130 of the film layer 106, which is due to the thickness of the stacked layer disposed on the base layer 130 being much smaller than the thickness of the base layer 130. For example, the overall thickness of the stacked layer composed of the dielectric layer 132, the bottom conductive layer 134, the piezoelectric layer 136, the top conductive layer 138, and the passivation layer 140 may be only 1% of the thickness of the base layer 130 disposed thereunder. /3 to 1/10.

In order to enable those skilled in the art to realize the present disclosure, the method of manufacturing a piezoelectric micromachined ultrasonic transducer will be further described below. In addition, because piezoelectric micro-machined ultrasonic transducers can be manufactured through standard CMOS processes, related electronic components, such as field-effect devices, can also be manufactured through the same CMOS process on the same substrate of piezoelectric micro-machined ultrasonic transducers. Crystals, amplifiers and integrated circuits.

FIG. 3 is a diagram illustrating after a barrier structure is formed on a substrate according to an embodiment of the disclosure Schematic diagram of the cross-section. FIG. 10 is a flowchart showing a method of fabricating a piezoelectric micromachined ultrasonic transducer according to an embodiment of the present disclosure. Referring to FIG. 3, in step 202 of the method 200, a substrate 102 is provided. According to different requirements, the substrate 102 can be selected from a semiconductor substrate or an insulating substrate. According to an embodiment of the present disclosure, the substrate 102 may be a single crystal silicon substrate. Then, in step 204, etching can be performed from the front surface of the substrate 102 to form a barrier structure 104 protruding from the top surface 102s of the substrate 102. Specifically, in the process of fabricating the barrier structure 104, photolithography and etching processes can be performed. Since the size of the blocking structure 104 can be accurately defined through the lithography technology, the distance D between two opposite points of the blocking structure 104 can also be accurately controlled. The distance D can be used to precisely control the size of the barrier structure 104 and the size of the film layer 106.

FIG. 4 is a schematic diagram after a sacrificial layer is formed on the substrate according to an embodiment of the disclosure. Referring to FIG. 4, in step 206, a sacrificial layer including a first portion 122 and a second portion 124 may be formed on the substrate 102, wherein the top surface of the barrier structure 104 is exposed from the sacrificial layer. The first portion 122 of the sacrificial layer may be surrounded by the barrier structure 104, and the second portion 124 of the sacrificial layer may be separated from the first portion 122 by the barrier structure 104. According to an embodiment of the present disclosure, the process of forming the sacrificial layer may include the following steps: (1) Sacrificial material is deposited on the substrate 102 (such as chemical vapor deposition or plasma enhanced chemical vapor deposition) so that the sacrificial material covers The top surface 104s of the blocking structure 104; and (2) planarizing the sacrificial material until the top surface 104s of the blocking structure 104 is exposed. In addition, according to another embodiment of the present disclosure, the process of forming the sacrificial layer may include the following steps: (1) performing a spin coating process to coat a layer of sacrificial material on the substrate 102; and (2) etching the sacrificial material until the barrier structure The top surface 104s of 104 is exposed. Therefore, through any of the above-mentioned processes for forming the sacrificial layer, the top surfaces 122s and 124s of the separated portions of the sacrificial layer can be aligned with the top surface 104s of the barrier structure 104.

Following step 208, a film layer is formed on the substrate 102. According to an embodiment of the present disclosure, step 208 may include sub-steps as shown in FIG. 5 and FIG. 6 respectively.

FIG. 5 is a schematic cross-sectional view after forming a base layer on the barrier structure and the sacrificial layer according to an embodiment of the disclosure. Referring to FIG. 5, a base layer 130 may be deposited on the barrier structure 104, on the first portion 122 of the sacrificial layer, and on the second portion 124 of the sacrificial layer. The base layer 130 may include materials with appropriate elasticity, such as crystalline silicon (c-Si), amorphous silicon (a-Si), silicon-rich nitride (SiN _x ), silicon carbide (SiC), etc., but is not limited thereto. Since the barrier structure 104 and the sacrificial layers 122 and 124 under the base layer 130 include a flat top surface, the bottom surface of the base layer 130 may also be a flat bottom surface. In addition, in order to obtain a flat top surface of the base layer 130, a flattening process may be selectively performed to flatten the top surface of the base layer 130.

FIG. 6 is a schematic cross-sectional view after forming a stacked layer on a base layer to form a film layer according to an embodiment of the disclosure. Referring to FIG. 6, a dielectric layer 132, a bottom conductive layer 134, a piezoelectric layer 136, a top conductive layer 138, and a passivation layer 140 can be sequentially deposited on the substrate 130 to form a film layer 150 disposed on the substrate 102. The dielectric layer 132 may be composed of an insulating material, such as SiO ₂ , SiON, AlN, or scandium-doped aluminum nitride (AlScN), to electrically insulate the bottom conductive layer 134 and the top conductive layer 138 from the base layer 130. According to an embodiment of the disclosure, the dielectric layer 132 can also be used as a seed layer for a plurality of layers subsequently deposited on the dielectric layer 132. In addition, the surface structure of the dielectric layer 132 may affect the crystallinity of the multiple layers deposited thereon. The bottom conductive layer 134 and the top conductive layer 138 may be the same or different materials composed of molybdenum (Mo), titanium (Ti), aluminum (Al), or platinum (Pt), but are not limited thereto. The piezoelectric layer 136 may be made of aluminum nitride (AlN), scandium-doped aluminum nitride (AlScN), lead zirconate titanate (PZT), zinc oxide (ZnO), polyvinylidene fluoride (PVDF), or lead niobate It is composed of lead titanate (PMN-PT), but it is not limited to this. The passivation layer 140 may be a selective layer made of an insulating material, such as SiO ₂ , SiON or AlN, but is not limited thereto. In addition, the material of the piezoelectric layer 136 is different from the base layer 130.

FIG. 7 is a schematic cross-sectional view after forming a contact pad according to an embodiment of the disclosure. Referring to FIG. 7, a plurality of contact holes may be formed in the film layer 150 to expose the bottom conductive layer 134 and the top conductive layer 138, respectively. Then, the contact pads, namely the first contact pad 114 and the second contact pad 116, can be filled into each contact hole. Thereby, the first contact pad 114 can be electrically coupled to the bottom conductive layer 134, and the second contact pad 116 can be electrically coupled to the top conductive layer 138.

FIG. 8 is a schematic cross-sectional view after a cut-off portion is formed in the film according to an embodiment of the disclosure. Referring to FIG. 8, by removing part of the film layer 150, the cut-off portions 112 and 152 can be formed. Therefore, the first portion 122 of the sacrificial layer may be exposed from the bottom of the cut-off portion 112, and a part of the base layer 130 may be exposed from the bottom of the cut-off portion 152. According to an embodiment of the present disclosure, although the cut-off portions 112 and 152 shown in FIG. 8 seem to be provided separately, when the structure shown in FIG. 8 is viewed from a top-down perspective, the cut-off portions 112 and 152 152 may also be a continuous distribution of pores, such as an annular pore. In addition, the planar shape of the cut-off portions 112 and 152 is not limited to the shape shown in FIG. 1. For example, the cut-off portions 112 and 152 may be polygonal pores partially surrounding the film layer 106.

FIG. 9 is a schematic cross-sectional view after a cavity penetrating the substrate is formed according to an embodiment of the disclosure. Referring to FIG. 9, in step 210, by etching the back surface of the substrate 102, a cavity 120 penetrating the substrate 102 can be formed. Therefore, the bottom surface of the first portion 122 of the sacrificial layer may be exposed from the cavity 120. The cavity 120 may include an opening O. The edge 120e of the cavity 120 will be adjacent to the film layer disposed on the front surface of the substrate 102, and the edge 120e of the cavity 120 may be used to define the opening O.

The length of the aperture defined by the opening O may be shorter than the distance D defined by the opposing points of the blocking structure 104. Since the distance D can be used to define the position of the film layer in the piezoelectric micromachined ultrasonic transducer, and the distance D is mainly defined by the blocking structure 104, even if the position or size of the opening O is slightly offset, it will not cause compression. The position and size of the film layer of the electro-micromechanical ultrasonic transducer have been changed.

Thereafter, in step 212, an etching process may be performed to remove the first portion 122 of the sacrificial layer exposed from the cavity 120. When the sacrificial layer is composed of silicon oxide, the etchant may be vaporous hydrofluoric acid (Vapor FH, VHF). When removing the sacrificial layer exposed from the cavity 120, since the etching selection ratio of the sacrificial layer compared with the barrier structure 104 and the base layer 130 is greater than 10, the etchant can only remove the first portion 122 of the sacrificial layer. In addition, since the barrier structure 104 prevents the etchant from reaching the second part 124 of the sacrificial layer, the second part 124 of the sacrificial layer will not be etched away during the etching process. Therefore, a structure as shown in Figure 2 can be obtained, and this structure includes a released membrane.

According to the above-mentioned embodiment of the present disclosure, since the barrier structure 104 is formed by etching the front surface of the substrate 102, the barrier structure 104 can be closely attached to the substrate 102 without peeling off the substrate 102. And can have vertical sidewalls. In addition, the size and position of the film layer 106 can be precisely defined without being affected by the size and position of the cavity 120 under the film layer 106, thereby effectively improving the resonance between the piezoelectric micromachined ultrasonic transducers 100 The frequency uniformity further improves the reliability and electrical performance of each piezoelectric micromechanical ultrasonic transducer.

The foregoing descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made in accordance with the scope of the patent application of the present invention shall fall within the scope of the present invention.

100: Piezoelectric micromachined ultrasonic transducer

102: Base

102s: top surface

104: blocking structure

106: Membrane

108: The main part

110: base

112: Truncated part

114: first contact pad

116: second contact pad

120: Cavity

120e: Edge

126: Sacrifice Layer

130: grassroots

132: Dielectric layer

134: bottom conductive layer

136: Piezo Layer

138: Top conductive layer

140: passivation layer

Claims (20)

A piezoelectric micromachined ultrasonic transducer (PMUT) includes: a substrate, including a cavity penetrating the substrate; a blocking structure, which protrudes from a top surface of the substrate by etching the substrate and surrounds the cavity And a film layer disposed on the cavity and attached to the barrier structure, wherein the substrate and the barrier structure include the same material, the material includes single crystal silicon, polycrystalline silicon, amorphous silicon, glass, or Ceramic material. The piezoelectric micromachined ultrasonic transducer according to claim 1, wherein the edge of the cavity is adjacent to the film layer. The piezoelectric micromachined ultrasonic transducer according to claim 1, wherein the blocking structure is a ring-shaped, polygonal or arc-shaped structure arranged along an edge of the film layer. The piezoelectric micromachined ultrasonic transducer according to claim 1, wherein the film layer is a multilayer structure. The piezoelectric micromechanical ultrasonic transducer according to claim 4, wherein the multilayer structure includes: a base layer; a dielectric layer disposed on the base layer; two conductive layers stacked on the base layer; and a piezoelectric The layer is arranged between the conductive layers. The piezoelectric micromachined ultrasonic transducer according to claim 5, wherein the composition of the base layer is different from the composition of the piezoelectric layer. The piezoelectric micromachined ultrasonic transducer according to claim 1, further comprising a cut-off part penetrating the film layer. The piezoelectric micromachined ultrasonic transducer according to claim 7, wherein the blocking structure is arranged along the periphery of the cut-off part. The piezoelectric micromachined ultrasonic transducer according to claim 1, further comprising a sacrificial layer disposed on the top surface of the substrate and surrounding the blocking structure. The piezoelectric micromachined ultrasonic transducer according to claim 7, wherein the cut-off part is a ring shape and surrounds a part of the film layer. A method for manufacturing a piezoelectric micromachined ultrasonic transducer includes: providing a substrate; etching the substrate to form a barrier structure protruding from the substrate; forming a sacrificial layer on the substrate, wherein the barrier structure is exposed The sacrificial layer; forming a film layer on the barrier structure and the sacrificial layer; forming a cavity penetrating the substrate to expose a part of the sacrificial layer; and using the barrier structure as an etching stop structure to remove the exposure The portion of the sacrificial layer out of the cavity. The method for manufacturing a piezoelectric micromachined ultrasonic transducer according to claim 11, wherein the blocking structure is a ring, polygon, or arc structure arranged along an edge of the film layer. The method for manufacturing a piezoelectric micromachined ultrasonic transducer according to claim 11, wherein the substrate and the blocking structure comprise the same material. The method for manufacturing a piezoelectric micromachined ultrasonic transducer according to claim 11, wherein the step of forming the sacrificial layer on the substrate includes: depositing a sacrificial material on the substrate and the barrier structure; and planarizing the sacrificial layer Material to expose the barrier structure. The method for manufacturing a piezoelectric micromachined ultrasonic transducer according to claim 11, wherein the film layer is a multilayer structure, and the film layer includes: a base layer; a dielectric layer disposed on the base layer; and two conductive layers A layer is stacked on the base layer; and a piezoelectric layer is arranged between the conductive layers. The method of manufacturing a piezoelectric micromachined ultrasonic transducer as described in claim 11, further comprising forming a cut-off portion penetrating the film layer. The method for manufacturing a piezoelectric micromachined ultrasonic transducer according to claim 16, wherein the blocking structure is arranged along the periphery of the cut-off part. The method for manufacturing a piezoelectric micromachined ultrasonic transducer according to claim 11, wherein when the step of forming the sacrificial layer on the substrate is completed, the sacrificial layer includes: a first part surrounded by the barrier structure; and A second part is separated from the first part by the blocking structure. The method of manufacturing a piezoelectric micromechanical ultrasonic transducer according to claim 18, wherein, when the step of removing the portion of the sacrificial layer exposed from the cavity is completed, the second portion of the sacrificial layer The line is retained on the substrate. The method for fabricating a piezoelectric micromachined ultrasonic transducer according to claim 11, wherein, in the step of removing the portion of the sacrificial layer exposed to the cavity, there is a gap between the sacrificial layer and the barrier structure The etching selection ratio is greater than 10.

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