CN112485775A

CN112485775A - Transduction device, transduction structure and manufacturing method thereof

Info

Publication number: CN112485775A
Application number: CN202011148036.6A
Authority: CN
Inventors: 邱品翔; 黄泰翔; 邱炜茹; 陈政翰; 李文渊
Original assignee: AU Optronics Corp
Current assignee: AU Optronics Corp
Priority date: 2020-04-10
Filing date: 2020-10-23
Publication date: 2021-03-12
Anticipated expiration: 2040-10-23
Also published as: TWI738290B; TW202138921A; CN112485775B

Abstract

The transduction structure includes a substrate, a first electrode, an inorganic layer, a first insulating layer, a second insulating portion, and a second electrode. The first electrode is disposed on the substrate. The inorganic layer is located on the first electrode and has a lower oscillation portion and holes located at two sides of the lower oscillation portion. The first insulating layer comprises an upper oscillating portion and a first insulating portion, the upper oscillating portion is located above the lower oscillating portion, the first insulating portion is located on the first electrode, and the first electrode, the first insulating portion and the lower oscillating portion form a cavity together. The second insulating parts are respectively positioned on the first insulating parts and are in contact with the first insulating parts through the holes, and the materials of the second insulating parts are different from those of the first insulating parts. The second electrode is located on the upper oscillation part, and the cavity is located between the first electrode and the second electrode.

Description

Transduction device, transduction structure and manufacturing method thereof

Technical Field

The invention relates to a transducer device, a transducer structure and a manufacturing method thereof.

Background

The ultrasonic imaging technology is to create an image by using the principle of ultrasonic reflection, for example, by transmitting vibration excited by an electronic pulse into a body, converting the vibration into a current after the vibration reaches the boundary of an object to be measured and rebounds, and further converting the current into an image to be presented. So that the ultrasonic transducer can be applied to doctor images, fingerprint identification, gesture identification and the like. Common ultrasonic transducers include three types of technologies, such as bulk piezoelectric ceramic transducers (bulk piezoelectric transducers), Capacitive Micromachined Ultrasonic Sensors (CMUTs), and Piezoelectric Micromachined Ultrasonic Sensors (PMUTs). The transmission of ultrasound waves may be affected if the reliability of the elements of the transducer is low.

Disclosure of Invention

The invention provides a transduction structure and a transduction device, wherein the surface flatness of an upper oscillation part is high.

The present invention provides a method for manufacturing a transducer structure, which does not need to etch a second insulating layer, thereby avoiding the risk of damaging an upper oscillating portion caused by over-etching the upper oscillating portion due to inaccurate etching process.

The transduction structure of the present invention includes a substrate, a first electrode, an inorganic layer, a first insulating layer, a plurality of second insulating portions, and a second electrode. The first electrode is disposed on the substrate. The inorganic layer is located on the first electrode, and the inorganic layer is provided with a lower oscillation part and a plurality of holes, and the holes are located on two sides of the lower oscillation part. The first insulating layer comprises an upper oscillating portion and a plurality of first insulating portions, the upper oscillating portion is located above the lower oscillating portion, the first insulating portions are located on the first electrodes, and the first electrodes, the first insulating portions and the lower oscillating portion form a cavity together. The second insulating parts are respectively positioned on the first insulating parts and respectively contact the first insulating parts through the holes, and the materials of the second insulating parts are different from those of the first insulating parts. The second electrode is located on the upper oscillation part, and the cavity is located between the first electrode and the second electrode.

The transducer device of the invention comprises a plurality of transducer structures and lines as described above. The first electrodes of the transduction structures are mutually separated along at least one direction, and the first electrodes are arranged in an array. The circuit is located at one side of the transduction structure, wherein the first electrodes of the transduction structure are electrically connected with each other through the circuit, and the circuit and the first electrodes are the same film layer.

The method of manufacturing the transducer structure of the present invention includes the following steps. A first electrode is formed on a substrate. A sacrificial layer is formed on the first electrode. An inorganic layer is formed on the sacrificial layer and the first electrode. And patterning the inorganic layer to form a plurality of upper holes and a lower oscillating portion, wherein the upper holes are positioned at two sides of the lower oscillating portion, and the sacrificial layer is exposed through the upper holes. The sacrificial layer is removed to form a lower hole and an accommodating space, wherein the lower hole is located below the upper hole, and the accommodating space is located below the lower oscillating portion. Forming a first insulating layer on the inorganic layer, wherein the first insulating layer has a plurality of first insulating portions and an upper oscillating portion, the upper oscillating portion is located above the lower oscillating portion, the first insulating portions are respectively filled in the lower holes, and the first electrode, the first insulating portions and the lower oscillating portion together form a cavity. And filling the second insulating parts into the upper holes respectively, wherein the second insulating parts are positioned on the first insulating parts respectively, and the material of the second insulating parts comprises photoresist.

Based on the above, the surface flatness of the upper oscillating portion of the transducer structure and the transducer device of the present invention is high. Therefore, the frequency of the ultrasonic wave provided by the oscillating membrane formed by the upper oscillating part and the lower oscillating part has high stability. The method for manufacturing the transducer structure of the invention can utilize the photomask to carry out the lithography process on the second insulating layer so as to remove part of the second insulating layer, thereby forming the second insulating part. Since the material of the second insulating layer is different from that of the first insulating layer, the upper oscillating portion is not damaged when a part of the second insulating layer is removed. And it does not need to etch the second insulation layer, so as to avoid the risk of damaging the upper oscillation part caused by over-etching the upper oscillation part due to the inaccurate etching process.

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

Drawings

Fig. 1-10 are cross-sectional views illustrating a process for fabricating a transducer structure according to an embodiment of the present invention.

FIG. 11 is a perspective view of the transducing structure of FIG. 10.

Fig. 12A is a perspective view of an ultrasound probe according to an embodiment of the invention.

FIG. 12B is a schematic top view of the transducer arrangement of FIG. 12A.

FIG. 12C is a schematic top view of a transducer arrangement according to another embodiment.

Fig. 13 is a partial image of fig. 12B under an electron microscope.

FIG. 14 is a cross-sectional view of FIG. 12B taken along section line 14-14'.

Fig. 15 is an enlarged schematic view of the region R of fig. 14.

FIGS. 16-21 are cross-sectional views illustrating a process flow for fabricating a transducer structure according to another embodiment of the present invention.

Wherein, the reference numbers:

10,10' transducing structure

14-14' cutting line

20,20a transducer device

30 ultrasonic probe

100 substrate

102,102a first electrode

104 sacrificial film Material

104A sacrificial layer

106 patterning the photoresist

108 mask

110 inorganic layer

112 first insulating layer

112A upper oscillating part

112B first insulating part

112C side wall part

112R groove

114,114' oscillating membrane

116 second insulating layer

116A second insulating part

118 mask

120,120' second electrode

122 line

124: line

200 casing

202 acoustic wave matching layer

204 backing material

206 acoustic lens

CVT cavity

D1 first direction

D2 second direction

R is a region

SP (SP-containing space)

SS side wall

t0, t1, t2 thickness

t00 height

t1', t2' thickness

TH1 upper hole

TH2 lower hole

Detailed Description

Various embodiments of the present invention can be understood by reading the following detailed description in conjunction with the accompanying drawings. It is noted that the various features of the drawings are not to scale as is standard practice in the industry. In fact, the dimensions of the features described may be arbitrarily increased or reduced for clarity of discussion.

Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the description to refer to the same or like parts.

The invention will be described in detail with reference to the following drawings, which are provided for illustration purposes and the like:

fig. 1-10 are cross-sectional schematic views of a process flow for fabricating a transducing structure 10 according to an embodiment of the present invention. Referring to fig. 1, first, a first electrode 102 is formed on a substrate 100. The substrate 100 may include a rigid substrate or a flexible substrate, and the material thereof is, for example, glass, plastic, or other suitable materials, or a combination thereof, but not limited thereto. In some embodiments, the material of the first electrode 102 may include a metal, such as aluminum, copper. In some embodiments, the first electrode 102 may be formed by Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), Atomic Layer Deposition (ALD), Vacuum Thermal Evaporation (VTE), sputtering (sputtering), or a combination thereof.

Referring to fig. 2, a sacrificial film material 104 is formed entirely on the first electrode 102. Next, a patterned photoresist 106 is formed on the sacrificial film material 104. In the present embodiment, the sacrificial film material 104 may include a metal, such as copper (Cu), titanium (Ti), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), molybdenum (Mo), tungsten (W), an Oxide of the metal, or Indium Tin Oxide (ITO). The patterned photoresist 106 is formed, for example, by forming a photoresist layer (not shown) on the sacrificial film 104, and performing a photolithography process on the photoresist layer by using a mask 108 to form the patterned photoresist 106.

Then, an etching process is performed on the sacrificial film material 104 using the patterned photoresist 106 as a mask, and then the patterned photoresist 106 is removed to form a sacrificial layer 104A on the first electrode 102, as shown in fig. 3. The patterned photoresist 106 is removed by, for example, a photoresist strip (strip) process. In the present embodiment, the thickness t0 of the sacrificial layer 104A is 500 angstroms

To 5000 angstroms.

Next, referring to fig. 4, an inorganic layer 110 is formed on the sacrificial layer 104A and the first electrode 102. For example, the material of the inorganic layer 110 is silicon nitride (SiNx). In the present embodiment, the thickness t1 of the inorganic layer 110 is, for example, 3000 angstroms to 9000 angstroms. Thereby, the thickness t1 of the deposited (as-deposited) inorganic layer 110 is small enough to avoid warping (bonding) of the substrate 100. In the present embodiment, the material of the inorganic layer 110 is, for example, silicon nitride (SiNx).

Referring to fig. 5, the inorganic layer 110 is patterned to form a plurality of upper holes TH1 and a lower oscillating portion 110A. For example, two upper holes TH1 may be formed. The upper holes TH1 are located at both sides of the lower oscillating portion 110A. In other words, the lower oscillating portion 110A is located between the upper holes TH 1. And both ends of the sacrificial layer 104A are exposed through the upper holes TH 1. The upper hole TH1 corresponds to an etching hole for removing the sacrificial layer 104A. In the present embodiment, the thickness t1 of the lower oscillating portion 110A is, for example, 3000 angstroms to 9000 angstroms.

Referring to fig. 6, the sacrificial layer 104A is removed by the upper hole TH1 to form a lower hole TH2 below the upper hole TH1 and a receiving space SP below the lower oscillating portion 110A. In the present embodiment, the method for removing the sacrificial layer 104A is, for example, an etching process.

Referring to fig. 7, a first insulating layer 112 is formed on the inorganic layer 110 and the first electrode 102. For example, the first insulating layer 112 includes an upper oscillating portion 112A and a plurality of first insulating portions 112B. For example, the first insulating layer 112 may include two first insulating portions 112B. The first insulating portions 112B are respectively filled into the lower holes TH2 through the upper holes TH1, so that the first insulating portions 112B are located on the first electrode 102, that is, the first insulating portions 112B contact the first electrode 102, whereby the first electrode 102, the first insulating portions 112B and the lower oscillating portion 110A together form a cavity CVT. The cavity CVT may be air or vacuum.

The upper oscillating portion 112A is located above the lower oscillating portion 110A. The thickness t2 of each first insulating portion 112B is greater than and/or equal to the height t00 of the cavity CVT (or the thickness t0 of the sacrificial layer 104A) to ensure reliability of the subsequent processes. For example, it is ensured that the second insulating layer 116 (see fig. 8) to be formed next on the first insulating layer 112 does not flow into the cavity CVT to affect the size of the cavity CVT, for example, without downsizing the cavity CVT. The frequency of the ultrasonic waves that can be generated by the known transduction structure 10 is inversely related to the size of the cavity CVT. That is, the larger the size of the cavity CVT, the lower the frequency, and the smaller the size of the cavity CVT, the higher the frequency. Since the size of the cavity CVT is not affected, the reliability of the frequency of the ultrasonic waves that can be generated by the transduction structure 10 can be thereby ensured. In the present embodiment, the thickness of the first insulating layer 112 is 1000 to 5500 angstroms. For example, the thickness t2 of the first insulating portions 112B is at least 500 a greater than the height t00 of the cavity CVT (or the thickness t0 of the sacrificial layer 104A), such as the thickness t2 of each first insulating portion 112B is 1000 a to 5500 a, and the thickness t2 of the upper oscillating portion 112A is 1000 a to 5500 a. In the present embodiment, the material of the first insulating layer 112 is the same as the material of the inorganic layer 110. For example, the material of the first insulating layer 112 is silicon nitride (SiNx). Thus, the upper oscillation part 112A of the first insulating layer 112 and the lower oscillation part 110A of the inorganic layer 110 can jointly form the oscillation film 114 of the transducer structure 10, the thickness t2 of the deposited (as-deposited) first insulating layer 112 (e.g., the upper oscillation part 112A and the first insulating part 112B) is sufficiently small to avoid warping (bending) of the substrate 100, and the problem of thick film etching uniformity is also avoided because the thickness t2 of the first insulating layer 112 is sufficiently small and no etching process needs to be performed on the first insulating layer 112.

In the present embodiment, the first insulating layer 112 further includes a sidewall portion 112C, and the sidewall portion 112C is located on the sidewall SS of the upper hole TH1 of the inorganic layer 110. In other words, the sidewall portion 112C extends from the top surface of the first insulating portion 112B to the sidewall SS of the upper hole TH1 of the inorganic layer 110 and then connects with the upper oscillating portion 112A, so that the sidewall portion 112C and each first insulating portion 112B together form the recess 112R. Thereby, it can be further ensured that the second insulating layer 116 (see fig. 8) to be formed next on the first insulating layer 112 does not flow into the cavity CVT to affect the size of the cavity CVT.

Referring to fig. 8, a second insulating layer 116 is formed on the first insulating layer 112. For example, the second insulating layer 116 covers the upper oscillating portion 112A of the first insulating layer 112, and the second insulating layer 116 fills the remaining space of the upper hole TH1 of the inorganic layer 110 and fills the sidewall 112C of the first insulating layer 112 and the groove 112R formed by the first insulating portions 112B. The second insulating layer 116 is formed by spin coating (spin coating). For example, the material of the second insulating layer 116 includes an organic material. In the present embodiment, the material of the second insulating layer 116 includes photoresist. The photoresist is a liquid material, so that a vacuum apparatus or a low temperature apparatus is not required to form the second insulating layer 116, thereby achieving process convenience. In the present embodiment, the thickness of the second insulating layer 116 is 0.5 to 3 μm.

Referring to fig. 9, a portion of the second insulating layer 116 is removed to form a plurality of second insulating portions 116A respectively filling the remaining spaces of the upper holes TH1 and the grooves 112R. For example, two second insulating portions 116A are formed to fill the remaining spaces of the two upper holes TH1 and the grooves 112R, respectively. The second insulating portions 116A are respectively located on the first insulating portions 112B, and the second insulating portions 116A respectively contact the first insulating portions 112B through the upper holes TH 1. In the present embodiment, each sidewall 112C is located between the lower oscillating portion 110A and each second insulating portion 116A along the horizontal direction.

In the present embodiment, the material of the second insulating layer 116 is different from the material of the first insulating layer 112, for example, the material of the second insulating layer 116 includes an organic material (such as a photoresist), and the second insulating layer 116 may be subjected to a photolithography process using a mask 118 to remove a portion of the second insulating layer 116, thereby forming a second insulating portion 116A. Since the material of the second insulating layer 116 is different from the material of the first insulating layer 112, the first insulating layer 112 is not removed when a portion of the second insulating layer 116 is removed. That is, the first insulating layer 112 is not damaged. For example, the upper oscillating portion 112A is not damaged. The frequency and stability of the ultrasonic waves that can be generated by the transducing structure 10 are known to be related to the characteristics of the oscillating membrane 114. For example, the frequency of the ultrasonic wave is positively correlated with the thickness of the oscillation film 114, and the stability of the ultrasonic wave is positively correlated with the surface flatness of the oscillation film 114. Since the upper oscillating portion 112A is not damaged, the surface flatness of the upper oscillating portion 112A is high, in other words, the surface roughness of the upper oscillating portion 112A is low, and the thickness t2 of the upper oscillating portion 112A is uniform. Therefore, the frequency of the ultrasonic wave provided by the oscillation film 114 formed by the upper oscillation part 112A and the lower oscillation part 110A has high stability, and the reliability of the oscillation film 114 is improved.

Since the upper holes TH1 of the inorganic layer 110 are respectively filled by the second insulating portion 116A, and the material of the second insulating portion 116A includes photoresist, the etching process for the second insulating layer 116 can be omitted. Without performing a precise etching process control on the second insulating layer 116, the risk of damaging the upper oscillating portion 112A due to over-etching of the upper oscillating portion 112A caused by a non-precise etching process is avoided, so that the process difficulty of the transducer structure 10 is reduced.

Referring to fig. 10, a second electrode 120 is formed on the upper oscillating portion 112A, wherein the cavity CVT is located between the first electrode 102 and the second electrode 120. In some embodiments, the material of the second electrode 120 may include metal, such as aluminum and copper. In some embodiments, the second electrode 120 may be formed by depositing a full-surface metal material layer (not shown) by Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), Atomic Layer Deposition (ALD), evaporation (VTE), Sputtering (SPT), or a combination thereof, and then forming the second electrode 120 by photolithography and etching processes. In this way, the transducer structure 10 of the present invention is completed. In the present embodiment, the transduction structure 10 is exemplified by a capacitive micro-ultrasonic transducer (CMUT). The first electrode 102 and the second electrode 120 serve as capacitances for sensing signals, and the cavity CVT can provide a space for the second electrode 120 to vibrate. When the ultrasonic wave acts on the second electrode 120, the second electrode 120 starts to vibrate, so that the capacitance between the first electrode 102 and the second electrode 120 changes, and a signal value can be obtained by using a receiving circuit (not shown) according to the change of the capacitance.

FIG. 11 is a perspective view of the transducing structure 10 of FIG. 10. For convenience of illustration, the first direction D1 and the second direction D2 are shown in fig. 11, wherein the first direction D1 and the second direction D2 intersect. In the embodiment, the first direction D1 is substantially perpendicular to the second direction D2, but the invention is not limited thereto. Referring to fig. 11, the second electrode 120 extends along a first direction D1.

Fig. 12A is a perspective view of an ultrasonic probe 30 according to an embodiment of the present invention. In the present embodiment, the ultrasonic probe 30 is exemplified by an arc-shaped probe (convex-probe). The ultrasonic probe 30 includes a housing 200, a transducer 20, an acoustic matching layer (acoustic matching layer)202, a backing material 204, an acoustic lens (acoustic lens)206, and a cable (not shown). The backing material 204 may reduce pulse duration, increasing axial resolution. The acoustic lens 206 is used for axial focusing and the acoustic matching layer 202 is used to reduce multiple reflections caused by differences in acoustic impedance (acoustic impedance) between the skin and the ultrasound probe 30.

FIG. 12B is a schematic top view of the transducer assembly 20 of FIG. 12A. FIG. 12C is a schematic top view of a transducer arrangement 20a according to another embodiment. Fig. 13 is a partial image of fig. 12B under an electron microscope. FIG. 14 is a cross-sectional view of FIG. 12B taken along section line 14-14'. Fig. 15 is an enlarged schematic view of the region R in fig. 14, and referring to fig. 12B, fig. 13, fig. 14 and fig. 15, the transducer device 20 includes a plurality of transducer structures 10 and at least one line 122. The structure of the transducing structure 10 is as described above and will not be described in detail herein. In the present embodiment, the first electrode 102 is disposed on the substrate 100 in a planar manner. And the top view shape of each second electrode 120 is a strip and is arranged in an array at intervals along the second direction D2. The circuit 122 is located at one side of the transducing structure 10, wherein the first electrodes 102 of the transducing structure 10 are electrically connected to each other through the circuit 122, and the circuit 122 and the first electrodes 102 are the same film layer. The transducer arrangement 20 further comprises a line 124, wherein the second electrodes 120 of the transducer structure 10 are electrically connected to each other via the line 124. In the present embodiment, the circuit 124 and the second electrode 120 are the same layer.

Referring to fig. 14 and 15, it can be seen that the surface flatness of the oscillation film 114 is high and the second insulation layer 116 (see fig. 8) does not flow into the cavity CVT.

Next, referring back to fig. 12C, for convenience of explanation, the upper oscillating portion 112A, the first insulating portion 112B, and the second insulating portion 116A are omitted from fig. 12C. In the present embodiment, the first electrodes 102a of the transducing structures 10 are separated from each other at least along the second direction D2, and the first electrodes 102a are arranged in an array along the second direction D2. In the present embodiment, the top view of each first electrode 102a is a stripe. Thereby, the transducer device 20a can be made to have high light transmittance.

FIGS. 16-21 are cross-sectional views illustrating a process flow for fabricating a transducing structure 10' according to another embodiment of the present invention. Referring to fig. 16, a first electrode 102, a sacrificial layer 104A and an inorganic layer 110 are sequentially formed on a substrate 100, and then a second electrode 120' is formed on the inorganic layer 110. The formation methods and materials of the first electrode 102, the sacrificial layer 104A and the inorganic layer 110 are the same as those of the manufacturing process shown in fig. 1 to 4, and thus are not described herein again. The second electrode 120 may be formed by depositing a whole metal material layer (not shown) by Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), Atomic Layer Deposition (ALD), evaporation (VTE), Sputtering (SPT) or a combination thereof, and then forming the second electrode 120 by photolithography and etching processes. For example, the material of the inorganic layer 110 is silicon nitride (SiNx). In the present embodiment, the thickness t1' of the inorganic layer 110 is, for example, 3000 angstroms to 9000 angstroms. Thereby, the thickness t1' of the deposited (as-deposited) inorganic layer 110 is small enough to avoid warping (bonding) of the substrate 100. In the present embodiment, the material of the inorganic layer 110 is, for example, silicon nitride (SiNx).

Next, referring to fig. 17, the inorganic layer 110 is patterned to form a plurality of upper holes TH1 and a lower oscillating portion 110A. For example, two upper holes TH1 may be formed. The upper holes TH1 are located at two sides of the lower oscillating portion 110A, in other words, the lower oscillating portion 110A is located between the upper holes TH 1. And the sacrificial layer 104A is exposed through the upper holes TH 1. The upper hole TH1 corresponds to an etching hole for removing the sacrificial layer 104A.

Referring to fig. 18, the sacrificial layer 104A is removed by the upper holes TH1 to form a plurality of lower holes TH2 respectively located below the upper holes TH1 and a receiving space SP located below the lower oscillating portion 110A. For example, two lower holes TH2 may be formed below the two upper holes TH1, respectively. The sacrificial layer 104A is removed by, for example, an etching process.

Referring to fig. 19, a first insulating layer 112 is formed on the inorganic layer 110 and the second electrode 120, wherein the first insulating layer 112 includes an upper oscillating portion 112A and a plurality of first insulating portions 112B. For example, the first insulating layer 112 includes two first insulating portions 112B. The first insulating portion 112B is filled in the lower holes TH2 below the upper holes TH1 through the upper holes TH1, so that the first insulating portion 112B is located on the first electrode 102, that is, the first insulating portion 112B contacts the first electrode 102, and thereby the first electrode 102, the first insulating portion 112B and the lower oscillating portion 110A together form a cavity CVT. In the present embodiment, the upper oscillating portion 112A is located above the lower oscillating portion 110A and the second electrode 120'. In other words, the second electrode 120' is located between the upper oscillating portion 112A and the lower oscillating portion 110A. In the present embodiment, the thickness t2' of the upper oscillating portion 112A is between 1000 angstroms and 5500 angstroms. Thereby, the upper oscillating portion 112A of the first insulating layer 112 and the lower oscillating portion 110A of the inorganic layer 110 may jointly constitute the oscillating film 114' of the transducing structure 10', and the thickness t2' of the deposited (as-disposed) first insulating layer 112 (e.g., the upper oscillating portion 112A and the first insulating portion 112B) is sufficiently small to avoid warping (bonding) of the substrate 100. Furthermore, since the thickness t2' of the first insulating layer 112 is small enough and the etching process for the first insulating layer 112 is not required, the problem of thick film etching uniformity is also avoided.

In the present embodiment, the first insulating layer 112 further includes a sidewall portion 112C, the sidewall portion 112C is located on a sidewall SS of the upper hole TH1 of the inorganic layer 110, in other words, the sidewall portion 112C extends from a top surface of the first insulating layer 112B to the sidewall SS of the upper hole TH1 of the inorganic layer 110.

Referring to fig. 20, a second insulating layer 116 is formed on the first insulating layer 112. For example, the second insulating layer 116 covers the upper oscillating portion 112A of the first insulating layer 112, and the second insulating layer 116 fills the remaining space of the upper hole TH1 of the inorganic layer 110 and fills the sidewall 112C of the first insulating layer 112 and the groove 112R formed by the first insulating portions 112B. The second insulating layer 116 is formed by, for example, spin coating. For example, the material of the second insulating layer 116 includes an organic material. In the present embodiment, the material of the second insulating layer 116 includes photoresist. The photoresist is a liquid material, so that a vacuum apparatus or a low temperature apparatus is not required to form the second insulating layer 116, thereby achieving process convenience.

Referring to fig. 21, a portion of the second insulating layer 116 is removed to form a plurality of second insulating portions 116A respectively filling the remaining spaces of the upper holes TH1 and the grooves 112R. For example, two second insulating portions 116A are formed to fill the remaining spaces of the two upper holes TH1 and the grooves 112R, respectively. The second insulating portions 116A are respectively located on the first insulating portions 112B, and the second insulating portions 116A respectively contact the first insulating portions 112B through the upper holes TH 1. In the present embodiment, each sidewall 112C is located between the lower oscillating portion 110A and each second insulating portion 116A along the horizontal direction.

In the present embodiment, the material of the second insulating layer 116 is different from the material of the first insulating portion 112B, for example, the material of the second insulating layer 116 includes an organic material (e.g., a photoresist), and the second insulating layer 116 may be subjected to a photolithography process using a mask 118 to remove a portion of the second insulating layer 116, thereby forming a second insulating portion 116A. Since the material of the second insulating layer 116 is different from the material of the first insulating layer 112, the first insulating layer 112 is not removed when a portion of the second insulating layer 116 is removed. That is, the first insulating layer 112 is not damaged. For example, the upper oscillating portion 112A is not damaged. The frequency and stability of the ultrasonic waves that can be generated by the transducing structure 10 are known to be related to the characteristics of the vibrating membrane 114'. For example, the frequency of the ultrasonic wave is positively correlated with the thickness of the oscillation film 114', and the stability of the ultrasonic wave is positively correlated with the surface flatness of the oscillation film 114'. Since the upper oscillating portion 112A is not damaged, the surface flatness of the upper oscillating portion 112A is high, in other words, the surface roughness of the upper oscillating portion 112A is low, and the thickness t2' of the upper oscillating portion 112A is uniform. Therefore, the frequency of the ultrasonic wave provided by the oscillation film 114' formed by the upper oscillation part 112A and the lower oscillation part 110A has high stability.

Since the upper holes TH1 of the inorganic layer 110 are respectively filled by the second insulating portion 116A, and the material of the second insulating portion 116A includes photoresist, the etching process for the second insulating layer 116 can be omitted. Without performing a precise etching process control on the second insulating layer 116, the risk of damaging the upper oscillating portion 112A due to over-etching of the upper oscillating portion 112A caused by a non-precise etching process is avoided, so that the process difficulty of the transducer structure 10' is reduced.

As mentioned above, since the material of the second insulating layer is different from the material of the first insulating layer, for example, the material of the second insulating layer includes an organic material (such as photoresist), a photolithography process may be performed on the second insulating layer using a mask to remove a portion of the second insulating layer, thereby forming the second insulating portion. Since the material of the second insulating layer is different from that of the first insulating layer, the first insulating layer is not removed when part of the second insulating layer is removed. That is, the first insulating layer is not damaged. For example, the upper oscillating portion is not damaged. The frequency and stability of the ultrasonic waves that can be generated by a transducing structure are known to be related to the characteristics of the oscillating membrane. For example, the frequency of the ultrasonic wave and the thickness of the oscillation film are positively correlated, and the stability of the ultrasonic wave and the surface flatness of the oscillation film are positively correlated. Since the upper oscillating portion is not damaged, the surface flatness of the upper oscillating portion is high, in other words, the surface roughness of the upper oscillating portion is low, and the thickness of the upper oscillating portion is uniform. Therefore, the frequency of the ultrasonic wave provided by the oscillating membrane formed by the upper oscillating part and the lower oscillating part has high stability, and the reliability of the oscillating membrane is improved.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it should be understood that various changes and modifications can be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A transducing structure, comprising:

a substrate;

a first electrode disposed on the substrate;

an inorganic layer on the first electrode, wherein the inorganic layer has a lower oscillation part and multiple holes on two sides of the lower oscillation part;

a first insulating layer including an upper oscillating portion and a plurality of first insulating portions, wherein the upper oscillating portion is located above the lower oscillating portion, the plurality of first insulating portions are located on the first electrode, and the first electrode, the plurality of first insulating portions and the lower oscillating portion together form a cavity;

a plurality of second insulating portions respectively located on the plurality of first insulating portions, wherein the plurality of second insulating portions respectively contact the plurality of first insulating portions through the plurality of holes, and the material of the plurality of second insulating portions is different from the material of the plurality of first insulating portions; and

and a second electrode located on the upper oscillation part, wherein the cavity is located between the first electrode and the second electrode.

2. The transducing structure of claim 1, wherein the plurality of second insulating portions comprise an organic material.

3. The transducing structure of claim 1 wherein the inorganic layer has a thickness of 3000 angstroms to 9000 angstroms.

4. The transducer structure of claim 1, wherein the first insulating layer further comprises a sidewall portion on sidewalls of the plurality of holes of the inorganic layer, such that the sidewall portion and each of the first insulating portions together form a recess.

5. A transducer assembly, comprising:

a plurality of transducing structures according to any of claims 1 to 4, wherein said first electrodes of each of said transducing structures are spaced apart from each other at least along a direction and each of said first electrodes are arranged in an array; and

and the circuit is positioned at one side of the plurality of transduction structures, wherein the first electrodes of the plurality of transduction structures are mutually and electrically connected through the circuit, and the circuit and the plurality of first electrodes are the same film layer.

6. A method of fabricating a transducing structure, comprising:

forming a first electrode on a substrate;

forming a sacrificial layer on the first electrode;

forming an inorganic layer on the sacrificial layer and the first electrode;

patterning the inorganic layer to form a plurality of upper holes and a lower oscillating portion, wherein the upper holes are positioned at two sides of the lower oscillating portion, and the sacrificial layer is exposed through the upper holes;

removing the sacrificial layer to form a plurality of lower holes respectively positioned below the plurality of upper holes and an accommodating space positioned below the lower oscillating part;

forming a first insulating layer on the inorganic layer, wherein the first insulating layer has a plurality of first insulating portions and an upper oscillating portion, the upper oscillating portion is located above the lower oscillating portion, the plurality of first insulating portions are respectively filled into the plurality of lower holes, and the first electrode, the plurality of first insulating portions and the lower oscillating portion together form a cavity; and

and filling a plurality of second insulating parts into the plurality of upper holes respectively, wherein the plurality of second insulating parts are positioned on the plurality of first insulating parts respectively, and the material of the plurality of second insulating parts comprises photoresist.

7. The method of claim 6, wherein filling the plurality of upper holes with the plurality of second insulating portions comprises:

forming a second insulating layer on the first insulating layer; and

and removing part of the second insulating layer to form the plurality of second insulating parts, wherein the first insulating layer is not removed when part of the second insulating layer is removed.

8. The method of claim 7, wherein the material of the second insulating layer is different from the material of the first insulating layer.

9. The method of claim 6, wherein the second insulating layer is formed by spin coating.

10. The method of claim 6, wherein the first insulating layer has a thickness of 1000 to 5500 angstroms.