CN217009223U - Piezoelectric micromechanical ultrasonic transducer packaging structure - Google Patents

Abstract

The utility model provides a piezoelectric micromechanical ultrasonic transducer packaging structure, which comprises: a substrate comprising opposing first and second surfaces; the supporting layer is arranged on the first surface, at least one cavity with an opening facing the first surface is formed in the supporting layer, and a vacuum sealed cavity is formed by the side wall of the cavity, the top wall of the cavity and the first surface in a surrounding mode; the piezoelectric film is arranged on the supporting layer, is at least positioned above the cavity and is directly supported by the top wall of the cavity; the welding pad is arranged on the supporting layer and is positioned on the outer side of the piezoelectric film; the metal bulge is arranged on one side of the second surface; the connecting structure is electrically connected with the metal bump and the welding pad; and an isolation layer disposed between the connection structure and the support layer such that the connection structure and the support layer are not in direct contact.

Description

Piezoelectric micromechanical ultrasonic transducer packaging structure

Technical Field

The utility model relates to the technical field of semiconductors, in particular to a piezoelectric micro-mechanical ultrasonic transducer packaging structure.

Background

Piezoelectric Micromachined Ultrasonic Transducer (PMUT) generally includes a substrate, a supporting layer, a Piezoelectric film, and the like, which are stacked in sequence, where the supporting layer is a film layer with a certain structural strength for supporting the Piezoelectric film, and includes a cavity, and the Piezoelectric film is often disposed above the cavity and directly supported by a top wall of the cavity.

At present, the package structure of the piezoelectric micromachined ultrasonic transducer further includes a pad disposed on the support layer and located outside the piezoelectric film, and a carrier plate disposed on the pad, wherein the pad is used for electrical signal transmission. Due to the arrangement position of the bonding pad, the existing piezoelectric micromachined ultrasonic transducer package structure has poor compatibility with Surface Mount Technology (SMT), which is the most popular Technology and process in the electronic assembly industry at present.

In view of the above, there is a need to provide a new package structure of piezoelectric micromachined ultrasonic transducer, which is compatible with surface mount technology.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a piezoelectric micromechanical ultrasonic transducer packaging structure.

In order to solve the above problems, the present invention provides a piezoelectric micromachined ultrasonic transducer package structure, including: a substrate comprising opposing first and second surfaces; the supporting layer is arranged on the first surface, at least one cavity with an opening facing the first surface is formed in the supporting layer, and a vacuum sealed cavity is formed by the side wall of the cavity, the top wall of the cavity and the first surface in a surrounding mode; the piezoelectric film is arranged on the supporting layer, is at least positioned above the cavity and is directly supported by the top wall of the cavity; the welding pad is arranged on the supporting layer and is positioned on the outer side of the piezoelectric film; the metal bulge is arranged on one side of the second surface; the connecting structure is electrically connected with the metal bump and the welding pad; and an isolation layer disposed between the connection structure and the support layer such that the connection structure and the support layer are not in direct contact.

As an optional technical solution, the side edge of the supporting layer is located outside the side edge of the substrate; the isolation layer is positioned on the side edge of the support layer, outside the side edge of the substrate and the second surface; at least part of the welding pads are positioned on the outer side of the side edge of the supporting layer, the connecting structure is a first conductive film layer, the first conductive film layer is positioned outside the isolating layer, and the first conductive film layer is electrically connected with the welding pads and the metal protrusions.

As an optional technical solution, the supporting layer includes a first through hole penetrating therethrough, a projection of the substrate on the supporting layer does not cover the first through hole, and the pad is exposed from the first through hole; the isolation layer comprises a first isolation section, and the first isolation section covers the hole wall of the first through hole; the connecting structure comprises a first conductive column, the first conductive column is filled in the first through hole, and the first conductive column is electrically connected with the welding pad.

As an optional technical solution, the substrate includes a second through hole penetrating therethrough, and the second through hole is communicated with the first through hole; the isolation layer comprises a second isolation section, and the second isolation section covers the hole wall of the second through hole; the connecting structure comprises a second conducting column, the second conducting column is filled in the second through hole, and two opposite ends of the second conducting column are electrically connected with the first conducting column and the metal bulge respectively.

As an optional technical solution, the support layer includes a third surface opposite to the first surface; the isolation layer comprises a third isolation section located at a part of the third surface outside the side edge of the substrate, the side edge of the substrate and the second surface; the connecting structure further comprises a second conductive film layer, the second conductive film layer is located on the outer side of the third isolation section, the second conductive film layer is electrically connected with the first conductive via, and the metal protrusion is arranged on the surface of one side, far away from the second surface, of the second conductive film layer.

As an optional technical solution, the material of the support layer is silicon.

As an alternative solution, the supporting layer is formed with a plurality of cavities opening towards the first surface.

As an optional technical scheme, the cavities are consistent in shape and size and are distributed at uniform intervals.

As an optional technical solution, the planar shape of the cavity is circular.

As an optional technical scheme, the size range of the inner diameter of the cavity is 10-100 mu m.

As an optional technical solution, the piezoelectric actuator further includes a support plate, the support plate is disposed on the pad and connected to the support layer, and the support plate is located outside the piezoelectric film.

As an optional technical solution, the connector further comprises a cladding layer, the cladding layer is located outside the connecting structure, wherein the metal protrusion is exposed from the cladding layer.

Compared with the prior art, the utility model provides the piezoelectric micromechanical ultrasonic transducer packaging structure, and the welding pads for transmitting electric signals on the supporting layer of the piezoelectric micromechanical ultrasonic transducer packaging structure are led out to the metal bulges below the substrate through the connecting structure, so that the piezoelectric micromechanical ultrasonic transducer packaging structure can be compatible with a surface mounting process, and the assembly efficiency with the substrate is improved.

The utility model is described in detail below with reference to the drawings and specific examples, but the utility model is not limited thereto.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic cross-sectional view of a piezoelectric micromachined ultrasonic transducer package structure according to a first embodiment of the present invention.

Fig. 2 is a schematic top view of a support layer in a first embodiment of the utility model.

Fig. 3 is a schematic cross-sectional view of a piezoelectric micromachined ultrasonic transducer package structure in a second embodiment of the present invention.

Fig. 4 is a schematic top view of a support layer in a second embodiment of the present invention.

Fig. 5 is a schematic cross-sectional view of a piezoelectric micromachined ultrasonic transducer package according to a third embodiment of the present invention.

Fig. 6 is a schematic top view of a support layer in a third embodiment of the present invention.

Fig. 7 is a schematic cross-sectional view of a piezoelectric micromachined ultrasonic transducer package according to a fourth embodiment of the present invention.

Fig. 8 is a schematic cross-sectional view of a piezoelectric micromachined ultrasonic transducer package structure in a fifth embodiment of the present invention.

Fig. 9 is a flowchart of a packaging method of a piezoelectric micromachined ultrasonic transducer provided in an embodiment of the present application.

Fig. 10 to 12 are schematic cross-sectional views illustrating a manufacturing process of each step of a packaging method of a piezoelectric micromachined ultrasonic transducer according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be clearly and completely described below with reference to the detailed description of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

For convenience in explanation, the description herein uses terms indicating relative spatial positions, such as "upper," "lower," "rear," "front," and the like, to describe one element or feature's relationship to another element or feature as illustrated in the figures. The spatially relative positional terms may include different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "above" other elements or features would then be oriented "below" or "above" the other elements or features. Thus, the exemplary term "below" can encompass both a spatial orientation of below and above.

One of the objectives of the present invention is to provide a piezoelectric micromachined ultrasonic transducer package structure, which includes a substrate, a supporting layer, a bonding pad, a piezoelectric film, and a metal bump located below the substrate, wherein the metal bump is electrically connected to the bonding pad through a connecting structure, the supporting layer is made of a silicon substrate, and the connecting structure is made of a conductive material, so that an isolation layer is disposed between the connecting structure and the supporting layer, and the isolation layer at least covers the supporting layer so that the connecting structure and the supporting layer are not in direct contact.

According to the utility model, the piezoelectric micro-mechanical ultrasonic transducer packaging structure is positioned on the welding pad for transmitting electric signals on the supporting layer and is led out to the metal protrusion below the substrate through the connecting structure, so that the piezoelectric micro-mechanical ultrasonic transducer packaging structure can be compatible with a surface mounting process, and the assembly efficiency with the substrate is improved.

As shown in fig. 1, the present invention provides a piezoelectric micromachined ultrasonic transducer package structure 100, which includes a substrate 110, the substrate 110 including a first surface 111 and a second surface 112 opposite to each other; the supporting layer 120 is disposed on the first surface 111, and is formed with at least one cavity 121 opening toward the first surface 111, and a sidewall 122 of the cavity 121, a top wall 123 of the cavity 121 and the first surface 111 enclose a vacuum-tight cavity; the piezoelectric film 130 is disposed on the support layer 120, at least above the cavity 121, and is directly supported by the top wall 123 of the cavity 121; the pad 140 is disposed on the supporting layer 120 and outside the piezoelectric film 130; the metal protrusion 180 is disposed on one side of the second surface 112; the connecting structure 170 electrically connects the metal bump 180 and the pad 140; the release layer 160 is positioned between the attachment structures 170 and the support layer 120 such that the attachment structures 170 and the support layer 120 are not in direct contact.

In this embodiment, the connection structure 170 is, for example, a first conductive film 170, and the first conductive film 170 is located at the side of the substrate 110 and the support layer 120 and extends to the second surface 112 to electrically connect the pad 140 and the metal bump 180. The pad 140 is electrically coupled to an electrode (not shown) in the piezoelectric film 130, the pad 140 serves as an input and output terminal for connecting the piezoelectric film 130 to an external circuit, so as to transmit an external electrical signal, and the first conductive film 170 is electrically connected to the pad 140 and the metal bump 180, so that the pad 140 and the external electrical signal can be transmitted to the metal bump 180 through the first conductive film 170. In other words, the transmission of the electrical signal on the pad 140 is led out to the metal bump 180 on the second surface 112 of the substrate 110 by the connection structure 170, and since the metal bump 180 is disposed on the second surface of the substrate 110, the piezoelectric micromachined ultrasonic transducer package 100 can be assembled with the circuit substrate 1000 by a surface mount process, in which the metal bump 180 is mounted on the pad 1010 on the circuit substrate 1000 to realize electrical connection.

In a preferred embodiment, the metal bump 180 may be a metal bump with a tin cap or a solder ball.

With continued reference to fig. 1, the isolation layer 160 is, for example, a dielectric film 160, and the dielectric film 160 is located on the second surface 112 and extends from the second surface 112 along the side 113 of the substrate 110 and the side 124 of the support layer 120 to completely cover the side 113 of the substrate 110 and the side 124 of the support layer 120, wherein the pad 140 is located at least partially outside the side 124 of the support layer 120, and the side 124 of the support layer 120 is located outside the side 113 of the substrate 110. The first conductive film 170 is formed outside the dielectric film 160, and two ends of the first conductive film 170 are electrically connected to the pad 140 and the metal bump 180, respectively.

In this embodiment, a portion of the dielectric film 160 is entirely located on the second surface 112, but not limited thereto. In other embodiments of the present invention, a portion of the dielectric film 160 may also cover a portion of the second surface 112, wherein the portion of the dielectric film 160 is sandwiched between the first conductive film 170 and the second surface 112, so that the adhesion strength of the first conductive film 170 on the second surface 112 side is increased, and the combination stability of the connection structure and the metal bump on the substrate is improved.

In a preferred embodiment, a carrier 150 is further disposed on the supporting layer 120, and the carrier 150 is located outside the piezoelectric film 130 and stacked on the pad 140. The surface of the carrier board 150 facing the supporting layer 120 can also be used as a connecting surface to connect with the covering layer 190 located outside the connecting structure 170. In addition, the covering layer 190 also forms a notch, and the metal protrusion 180 is exposed from the corresponding notch.

In a preferred embodiment, the substrate 110 is a glass substrate, a dry film, a silicon wafer, or other suitable substrate material with certain structural strength.

In a preferred embodiment, the piezoelectric film 130 includes a piezoelectric layer and electrode layers disposed above and below the piezoelectric layer, and is configured to perform flexural motion and/or vibration when receiving or transmitting acoustic or ultrasonic signals.

In a preferred embodiment, the material of the supporting layer 120 is silicon, and a blind cavity 121 is formed by etching therein, so as to form a closed vacuum chamber in cooperation with the first surface 111 of the substrate 110, and to leave a portion of the top wall 123 of the supporting layer 120 without etching the cavity 121 for directly supporting the piezoelectric film 130. The supporting layer 120 is directly formed on the wafer-level silicon substrate, so that the process production efficiency can be greatly improved.

In other embodiments of the present invention, the support layer 120 may also be made of silicide material such as silicon dioxide.

In addition, the support layer 120 and the substrate 110 may be fixed by a bonding layer, the bonding layer may achieve an adhesion effect on one hand and play a role in enhancing the sealing performance on the other hand, and the bonding layer may be a polymer bonding material, such as a polymer material, e.g., silicon gel, epoxy resin, benzocyclobutene, or the like.

As shown in fig. 2, the planar shape of the cavity 121 is circular, and the overall cylindrical shape of the cavity 121 facilitates formation of a uniform size structure during an etching process. Wherein, the inner diameter of the cavity 121 is 10-100 μm.

In other embodiments of the present invention, the structure of the cavity 121 may be adjusted to a square, rectangular parallelepiped, polygonal parallelepiped, or the like according to the structural requirements of the PMUT.

Further, in the present invention, the number of the cavities 121 may be one or more, and when the number of the cavities 121 is plural, it is preferable that the plural cavities 121 have the same shape and size and are uniformly spaced.

Specifically, as shown in fig. 1 and 2, in the first embodiment of the present invention, a cavity 121 is formed in the support layer 120, the planar shape of the cavity 121 is circular, and the single cavity 121 is formed to maximize the vibration area of the piezoelectric film 130 disposed thereon, thereby achieving a higher vibration frequency.

As shown in fig. 3 and 4, in the second embodiment of the present invention, 4 cavities 121 are disposed in a support layer 120 'of a piezoelectric micromachined ultrasonic transducer package 100', the cavities 121 are circular in plan view, the support layer 120 'is substantially square in plan view, along two central axes, namely, a transverse axis and a vertical axis, the support layer 120' is uniformly divided into four regions, one cavity 121 is disposed in each region, and a piezoelectric film 130 completely covers the 4 cavities 121.

In addition, the same reference numerals in fig. 3 and 4 as those in fig. 1 and 2 denote the same elements having similar functions, and are not described in detail.

As shown in fig. 5 and fig. 6, in the third embodiment of the present invention, in the piezoelectric micromachined ultrasonic transducer package structure 100 ", 16 cavities 121 are disposed in the support layer 120", the cavities 121 are circular in planar shape, the support layer 120 "is substantially square in planar shape, the cavities 121 are arranged to form a 4 × 4 square array and are uniformly distributed on the support layer 120", and the piezoelectric film 130 completely covers the 16 cavities 121.

As the number of the cavities 121 is increased, the overall volume of the cavities 121 is reduced, the vibration area of the piezoelectric film 130 disposed thereon is reduced, and the vibration frequency is reduced, but a denser vibration signal can be obtained, so that the requirement of PMUT for outputting different vibration signals can be satisfied by adjusting the number of the cavities 121. In addition, because the cavities 121 in the utility model are micron-sized, the requirement on manufacturing accuracy is lower, and the cavity array can be manufactured on the supporting layer more easily through etching.

In addition, the same reference numerals in fig. 5 and 6 as those in fig. 1 and 2 denote the same elements having similar functions, and are not described in detail.

As shown in fig. 7, a piezoelectric micromachined ultrasonic transducer package 200 is further provided in the fourth embodiment of the present invention, which includes a substrate 210, where the substrate 210 includes a first surface 211 and a second surface 212 opposite to each other; the supporting layer 220 is disposed on the first surface 211, and is formed with at least one cavity 221 opening toward the first surface 211, and a sidewall 222 of the cavity 221, a top wall 223 of the cavity 221 and the first surface 211 enclose a vacuum-tight cavity; the piezoelectric film 230 is disposed on the support layer 220, at least above the cavity 221, and is directly supported by the top wall 223 of the cavity 221; the bonding pad 240 is disposed on the supporting layer 220 and outside the piezoelectric film 230; the metal protrusion 280 is disposed on one side of the second surface 212; the connection structure 270 electrically connects the metal bump 280 and the pad 240; the release layer 260 is positioned between the attachment structures 270 and the support layer 220 such that the attachment structures 270 and the support layer 220 are not in direct contact.

As shown in fig. 7, a connection structure 270, such as a conductive via structure, includes a first conductive via 271 and a second conductive via 272 electrically connected, where the first conductive via 271 is embedded in a first through hole of the support layer 220; the second conductive via 272 is embedded in the second through hole of the substrate 210; the first through hole and the second through hole are communicated up and down.

The isolation layer 260 includes a first isolation section 261 and a second isolation section 262, the first isolation section 261 is located outside the hole wall of the first via, and the second isolation section 262 covers outside the hole wall of the second via, wherein the first isolation section 261 and the second isolation section 262 are dielectric films, respectively.

It should be noted that the first isolation section 261 and the second isolation section 262 may be made independently, or may be made integrally at the same time; similarly, the first conductive via 271 and the second conductive via 271 may be separately manufactured, or may be simultaneously manufactured and integrally formed.

Wherein, the pad 240 is exposed from an end of the first through hole away from the first surface 211 and electrically connected to the first conductive via 271; the metal bump 280 is disposed on the second surface 212 and electrically connected to the second conductive via 272, and preferably, the second conductive via 272 further includes a pad bump 273 exposed from the second surface 212, wherein the metal bump 280 is disposed on the pad bump 273.

In the piezoelectric micromachined ultrasonic transducer package structure 200, through holes are formed on the substrate 210 and the supporting layer 220 by a hole-opening process, and the through holes are filled with an isolation layer such as a dielectric film and a conductive pillar such as a copper pillar, which are not in direct contact with the substrate and the supporting layer, so that the electrical signal on the bonding pad 240 is transmitted and led out to the metal bump 280. On one hand, the conduction column shortens the transmission path of the electric signal, improves the electric signal transmission efficiency of the piezoelectric micro-mechanical ultrasonic transducer packaging structure, and avoids energy consumption damage; on the other hand, the hole opening process can be used for manufacturing on a wafer-level substrate, and is high in precision, simple in process and easy to process.

In addition, a carrier plate 250 is disposed on the support layer 220, and is located outside the piezoelectric film 230 and stacked on the bonding pad 240.

As shown in fig. 8, the fifth embodiment of the present invention further provides a piezoelectric micromachined ultrasonic transducer package structure 300, which includes a substrate 310, where the substrate 310 includes a first surface 311 and a second surface 312, which are opposite to each other; the supporting layer 320 is disposed on the first surface 311, and is formed with at least one cavity 321 opening toward the first surface 311, a sidewall 322 of the cavity 321, a top wall 323 of the cavity 321, and the first surface 311 enclosing a vacuum-tight cavity; the piezoelectric film 330 is disposed on the support layer 320, at least above the cavity 321, and directly supported by the top wall 323 of the cavity 321; the bonding pad 340 is disposed on the support layer 320 and outside the piezoelectric film 330; the metal protrusion 380 is disposed on one side of the second surface 312; the connection structure 370 electrically connects the metal bump 380 and the pad 340; the release layer 360 is positioned between the attachment structures 370 and the support layer 320 such that the attachment structures 370 and the support layer 320 are not in direct contact.

As shown in fig. 8, the connection structure 370 includes a first conductive via 371 and a second conductive film 372, which are electrically connected, wherein the first conductive via 371 is embedded in a first through hole of the supporting layer 320, and a projection on the supporting layer 320 of the substrate 310 does not cover the first through hole; the second conductive film 372 extends from the second surface 312 of the substrate 310 along the side 313 of the substrate 310 to electrically connect to the first conductive via 371.

The isolation layer 360 includes a first isolation section 361 and a third isolation section 362, the first isolation section 361 is located outside the hole wall of the first through hole, the third isolation section 362 is sandwiched between the substrate 310 and the second conductive film 372, so that the second conductive film 372 does not directly contact with the substrate 310, the third isolation section 362 is located on the second surface 312 of the substrate 310, the side 313 of the substrate 310, and a third surface of the support layer 320 opposite to the first surface 311, the third isolation section 362 includes an opening, and the first conductive via 371 is exposed from the opening; the first isolation section 361 and the third isolation section 362 are dielectric films, respectively.

In the piezoelectric micromachined ultrasonic transducer package structure 300, a through hole is formed on the supporting layer 320 by a hole opening process, and an isolation layer such as a dielectric film and a conductive pillar such as a copper pillar are filled in the through hole, and the copper pillar and the supporting layer are not in direct contact; forming an isolation layer and a conductive film on the substrate by cutting the substrate 310 so that the conductive via in the through hole of the support layer 320 is exposed; the electric signal transmission on the bonding pad 340 is led out to the metal bump 380 by using the conductive film and the conductive via. On one hand, the conduction column shortens the transmission path of the electric signal, improves the electric signal transmission efficiency of the piezoelectric micro-mechanical ultrasonic transducer packaging structure, and avoids energy consumption damage; on the other hand, the process of combining the conducting column and the conducting film avoids forming a through hole with overlarge depth, and is easier to realize in the packaging process.

In addition, a carrier 350 is disposed on the supporting layer 320, and is located outside the piezoelectric film 330 and stacked on the bonding pads 340. A cladding layer 390 is formed outside the second conductive film 372 to prevent the second conductive film 372 from being directly exposed.

As shown in fig. 9, the present invention also provides a method 400 for packaging a piezoelectric micromachined ultrasonic transducer, comprising:

providing a substrate, and arranging the substrate on a temporary carrier plate;

thinning the substrate to form a supporting layer, forming at least one cavity on one surface of the supporting layer, and reserving part of the supporting layer at least at the bottom of the cavity;

providing a substrate, and inversely arranging the supporting layer on a first surface of the substrate;

stripping the temporary carrier plate, and arranging a piezoelectric film and a welding pad on the surface of the support layer;

removing part of the substrate and part of the supporting layer, and at least exposing part of the welding pad;

forming an isolation layer at least covering the support layer and the exposed area of the substrate;

forming a connecting structure, wherein the connecting structure is electrically connected with the welding pad, at least part of the connecting structure is exposed out of one side of the second surface of the substrate, and the second surface is opposite to the first surface;

and forming metal bumps on the connecting structures of the second surface.

In a preferred embodiment, the method further comprises: forming a second through hole in the substrate; forming a first through hole in the supporting layer, wherein the first through hole is communicated with the second through hole and is connected with the welding pad; forming a first isolation section covering the hole wall of the first through hole and a second isolation section covering the hole wall of the second through hole; and forming a first conducting column and a second conducting column in the first through hole and the second through hole.

In a preferred embodiment, the method further comprises: forming a first through hole in the supporting layer, wherein at least part of the welding pad is exposed out of the first through hole; forming a first isolation section covering the hole wall of the first through hole; forming a first conducting column in the first through hole; forming a third isolation section on the second surface of the substrate after cutting, the side edge of the substrate and a third surface of the support layer facing the substrate, the first isolation section and the third isolation section constituting the isolation layer; optionally forming an opening in the third isolation section, the first conductive via being exposed from the opening; and forming a second conductive film layer outside the third isolation section, wherein the second conductive film layer is electrically connected with the first conductive via through the opening.

In a preferred embodiment, the method further comprises: providing a carrier plate; and connecting the carrier plate and the support layer; the support plate is located above the welding pad and located on the outer side of the piezoelectric film.

The following will describe in detail with reference to fig. 10 to fig. 12, taking the piezoelectric micromachined ultrasonic transducer package structure 300 shown in fig. 8 as an example, the process of each step in the above-mentioned packaging method 400 for piezoelectric micromachined ultrasonic transducers will be described.

As shown in fig. 10, a substrate 320 'is provided, the substrate 320' is disposed on the temporary carrier 2000; thinning the substrate 320' to form a support layer 320, etching at least one cavity 321 on one side of the support layer 320, and leaving a portion of the support layer 320 at the bottom of the cavity 321 (corresponding to the top wall 323 of the cavity 321); providing a substrate 310, and inversely attaching a support layer 320 forming a cavity 321 on a first surface 311 of the substrate 310; the temporary carrier 2000 is peeled off, and the piezoelectric film 330 and the bonding pads 340 are disposed on the surface of the support layer 320 away from the substrate 310. The bonding pads 340 are located outside the piezoelectric film 330, and the piezoelectric film 330 is directly supported by the top wall 323 of the cavity 321, and the sidewall 322 of the cavity 321, the top wall 323 of the cavity 321, and the first surface 311 form a vacuum-tight cavity.

As shown in fig. 10 and 11, the substrate 310 is cut to form a substrate 310 having a trapezoidal cross section; forming a first through hole 326 on the supporting layer 320, wherein the first through hole 326 penetrates through the supporting layer 320, and a projection of the substrate 310 on the supporting layer 320 does not cover the first through hole; an isolation layer 360 is formed, wherein the isolation layer 360 includes a first isolation section 361 and a third isolation section 362, the first isolation section 361 is located outside the hole wall of the first via 326, and the third isolation section 362 is located on the second surface 312 and the side 313 of the substrate 310 and the third surface 325 exposed from the side 313 of the substrate 310.

Preferably, the third isolation section 362 further includes an opening in communication with the first through-hole 326.

In this embodiment, the first isolation section 361 and the third isolation section 362 are formed in one step, for example.

As shown in fig. 12, a first conductive via 371 is formed in the first via 326 of the support layer 320; a second conductive film 372 is formed outside the third isolation section 362, and the first conductive via 371 and the second conductive film 372 form a connection structure 370.

A metal bump 380 is formed on the surface of the second conductive film 372 on the second surface 312.

A cladding layer 390 is formed outside the second conductive film 372 to prevent the second conductive film 372 from being directly exposed.

In the above piezoelectric micromachined ultrasonic transducer package structure 300, the substrate 310 is cut, through holes are etched on the third surface 325 of the support layer 320 exposed from the side of the substrate 310 after cutting, isolation layers are sequentially formed, a conductive via is filled into the through holes to form a conductive film extending to one side of the second surface, and the conductive via and the missile film are used to together lead out the electrical signal in the pad 340 to the metal bump 380 on the second surface of the substrate.

In summary, the present invention provides a piezoelectric micromachined ultrasonic transducer package structure, in which a bonding pad for transmitting an electrical signal on a supporting layer of the piezoelectric micromachined ultrasonic transducer package structure is led out to a metal protrusion below a substrate through a connection structure, so that the piezoelectric micromachined ultrasonic transducer package structure can be compatible with a surface mounting process, and the assembly efficiency with a substrate is improved.

The present invention has been described in relation to the above embodiments, which are only exemplary of the implementation of the present invention. Furthermore, the technical features mentioned in the different embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. It is to be noted that the present invention may take various other embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the utility model as defined in the appended claims.

Claims (12)

1. A piezoelectric micromachined ultrasonic transducer package, comprising:

a substrate comprising opposing first and second surfaces;

the supporting layer is arranged on the first surface, at least one cavity with an opening facing the first surface is formed in the supporting layer, and a vacuum sealed cavity is formed by the side wall of the cavity, the top wall of the cavity and the first surface in a surrounding mode;

the piezoelectric film is arranged on the supporting layer, is at least positioned above the cavity and is directly supported by the top wall of the cavity;

the welding pad is arranged on the supporting layer and is positioned on the outer side of the piezoelectric film;

the metal bulge is arranged on one side of the second surface;

the connecting structure is electrically connected with the metal bump and the welding pad; and

an isolation layer disposed between the connection structure and the support layer such that the connection structure and the support layer are not in direct contact.

2. The piezoelectric micromachined ultrasonic transducer package of claim 1, wherein sides of the support layer are located outside sides of the substrate; the release layer is positioned on the side edge of the support layer, outside the side edge of the substrate and the second surface;

at least part of the welding pads are positioned on the outer side of the side edge of the supporting layer, the connecting structure is a first conductive film layer, the first conductive film layer covers the outside of the isolating layer, and the first conductive film layer is electrically connected with the welding pads and the metal protrusions.

3. The piezoelectric micromachined ultrasonic transducer packaging structure of claim 1, wherein the support layer comprises a first through hole penetrating through the support layer, a projection of the substrate on the support layer does not cover the first through hole, and the pad is exposed from the first through hole;

the isolation layer comprises a first isolation section, and the first isolation section covers the hole wall of the first through hole;

the connecting structure comprises a first conductive column, the first conductive column is filled in the first through hole, and the first conductive column is electrically connected with the welding pad.

4. The piezoelectric micromachined ultrasonic transducer package structure of claim 3, wherein the substrate includes a second through hole therethrough, the second through hole being in communication with the first through hole; the isolation layer comprises a second isolation section, and the second isolation section covers the hole wall of the second through hole;

the connecting structure comprises a second conducting column, the second conducting column is filled in the second through hole, and two opposite ends of the second conducting column are electrically connected with the first conducting column and the metal bulge respectively.

5. The piezoelectric micromachined ultrasonic transducer package structure of claim 3, wherein the support layer comprises a third surface opposite the first surface; the isolation layer comprises a third isolation section on the third surface outside a side edge of the substrate, the side edge of the substrate, and the second surface;

the connecting structure further comprises a second conductive film layer, the second conductive film layer covers the outer side of the third isolation section, the second conductive film layer is electrically connected with the first conductive via, and the metal protrusion is arranged on the surface of one side, far away from the second surface, of the second conductive film layer.

6. The piezoelectric micromachined ultrasonic transducer package structure of claim 1, wherein the support layer material is silicon.

7. The piezoelectric micromachined ultrasonic transducer package structure of claim 1, wherein the support layer is formed with a plurality of cavities opening toward the first surface.

8. The piezoelectric micromachined ultrasonic transducer package of claim 7, wherein the plurality of cavities are uniform in shape and size and are evenly spaced.

9. The piezoelectric micromachined ultrasonic transducer package structure of any one of claims 1 to 8, wherein the cavity plane shape is a circle.

10. The piezoelectric micromachined ultrasonic transducer package structure of any one of claims 1 to 8, wherein the cavity inner diameter dimension ranges from 10 to 100 μm.

11. The package structure of claim 1, further comprising a carrier disposed on the pad and connected to the support layer, wherein the carrier is located outside the piezoelectric film.

12. The piezoelectric micromachined ultrasonic transducer package structure of claim 1, further comprising a cladding layer covering the outside of the connection structure, wherein the metal bump is exposed from the cladding layer.

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