CN112485775B - Transduction device, transduction structure and manufacturing method thereof - Google Patents
Transduction device, transduction structure and manufacturing method thereof Download PDFInfo
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- CN112485775B CN112485775B CN202011148036.6A CN202011148036A CN112485775B CN 112485775 B CN112485775 B CN 112485775B CN 202011148036 A CN202011148036 A CN 202011148036A CN 112485775 B CN112485775 B CN 112485775B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
- G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
- G01S7/521—Constructional features
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Abstract
The transduction structure comprises a substrate, a first electrode, an inorganic layer, a first insulating layer, a second insulating part and a second electrode. The first electrode is disposed on the substrate. The inorganic layer is positioned on the first electrode and provided with a lower oscillating part and holes positioned at two sides of the lower oscillating part. The first insulating layer comprises an upper oscillating part and a first insulating part, the upper oscillating part is positioned on the lower oscillating part, the first insulating part is positioned on the first electrode, and the first electrode, the first insulating part and the lower oscillating part jointly form a cavity. The second insulating parts are respectively arranged on the first insulating parts and are contacted 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 positioned above the upper oscillating portion, and the cavity is positioned between the first electrode and the second electrode.
Description
Technical Field
The invention relates to a transduction device, a transduction structure and a manufacturing method thereof.
Background
Ultrasonic imaging techniques use the principle of ultrasonic reflection to create images, for example, by transmitting vibrations excited by an electronic pulse into the body, and converting the vibrations into currents after they reach the boundary of the object to be measured and then into image presentation. 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 technology, such as bulk piezoelectric ceramic transducers (bulk piezoelectric ceramics transducer), capacitive micromachined ultrasonic sensors (capacitive micromachined ultrasonic transducer; CMUT), and piezoelectric micromachined ultrasonic sensors (piezoelectric micromachined ultrasonic transducer; PMUT). If the transducer has low element reliability, the transmission of ultrasound waves may be affected.
Disclosure of Invention
The invention provides a transduction structure and a transduction device, wherein the surface flatness of an upper oscillating part of the transduction structure is high.
The invention provides a manufacturing method of a transduction structure, which does not need to etch a second insulating layer, and avoids the risk of damaging an upper oscillating part caused by over etching of the upper oscillating part 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 positioned on the first electrode, and is provided with a lower oscillating part and a plurality of holes, and the holes are positioned on two sides of the lower oscillating 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 plurality of first insulating portions are located on the first electrode, and the first electrode, the first insulating portions and the lower oscillating portion jointly form a cavity. The second insulating parts are respectively positioned on the first insulating parts, the second insulating parts are respectively contacted 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 positioned above the upper oscillating portion, and the cavity is positioned between the first electrode and the second electrode.
The transducer device of the present invention comprises a plurality of transducer structures and lines as described above. The first electrodes of each transduction structure are separated from each other along at least one direction, and are arranged in an array. The circuit is positioned 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 manufacturing method of the transduction structure comprises 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. The inorganic layer is patterned to form a plurality of upper holes and a lower oscillating portion, 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 below the upper hole and a containing space below the lower oscillating part. And forming a first insulating layer on the inorganic layer, wherein the first insulating layer is provided with a plurality of first insulating parts and an upper oscillating part, the upper oscillating part is positioned on the lower oscillating part, the first insulating parts are respectively filled in the lower holes, and the first electrode, the first insulating parts and the lower oscillating part jointly form a cavity. The second insulating parts are respectively filled in the upper holes, and are respectively positioned on the first insulating parts, wherein the material of the second insulating parts comprises photoresist.
Based on the above, the transduction structure and the transduction device of the present invention have high surface flatness of the upper oscillating portion. Thus, the frequency of the ultrasonic wave provided by the oscillation film formed by the upper oscillation part and the lower oscillation part has high stability. The manufacturing method of the transduction structure of the invention can utilize the photomask to carry out a micro-imaging process on the second insulation layer so as to remove part of the second insulation layer, thereby forming a second insulation 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 the second insulating layer does not need to be etched, so that the risk of damaging the upper oscillating portion caused by over etching of the upper oscillating portion due to inaccurate etching process is avoided.
The invention will now be described in more detail with reference to the drawings and specific examples, which are not intended to limit the invention thereto.
Drawings
Fig. 1 to 10 are schematic cross-sectional views illustrating a manufacturing process of a transducer structure according to an embodiment of the invention.
Fig. 11 is a perspective view of the transduction structure of fig. 10.
Fig. 12A is a schematic perspective view of an ultrasonic probe according to an embodiment of the present invention.
Fig. 12B is a schematic top view of the transducer of fig. 12A.
FIG. 12C is a schematic top view of a transducer device according to another embodiment.
Fig. 13 is a partial image of fig. 12B under an electron microscope.
Fig. 14 is a cross-sectional image of fig. 12B along section line 14-14'.
Fig. 15 is an enlarged schematic view of the region R of fig. 14.
Fig. 16 to 21 are schematic cross-sectional views illustrating a manufacturing process of a transducer structure according to another embodiment of the invention.
Wherein, the reference numerals:
10,10' transduction structure
14-14': profile
20,20a transducer arrangement
30 ultrasonic probe
100 substrate
102,102a first electrode
104 sacrificial film material
104A sacrificial layer
106 patterning a photoresist
108 photomask
110 inorganic layer
112 first insulating layer
112A upper oscillating portion
112B first insulating portion
112C side wall portion
112R groove
114,114': oscillating film
116 second insulating layer
116A second insulating portion
118 mask
120,120': second electrode
122 line
124 line
200 casing
202 acoustic matching layer
204 backing material
206 acoustic lens
CVT cavity
D1 first direction
D2, second direction
R region
SP, accommodation space
SS side wall
t0, t1, t2 thickness
Height t00
t1', t2': thickness
TH1 upper hole
TH2 lower hole
Detailed Description
Various embodiments of the present invention will be understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that the various features of the drawings are not drawn to scale as is standard practice in the industry. In fact, the dimensions of the features may be arbitrarily increased or reduced for clarity of discussion.
Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The structural and operational principles of the present invention are described in detail below with reference to the accompanying drawings:
fig. 1-10 are schematic cross-sectional views of a manufacturing process of a transducer structure 10 according to an embodiment of the invention. Referring to fig. 1, first, a first electrode 102 is formed on a substrate 100. The substrate 100 may include a hard substrate or a flexible substrate, and the material thereof is, for example, glass, plastic, or other suitable materials, or a combination thereof, but is 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 (chemical vapor deposition; CVD), physical vapor deposition (physical vapor deposition; PVD), atomic layer deposition (atomic layer deposition; ALD), vacuum thermal evaporation (vacuum thermal evaporation; VTE), sputtering (sputtering), or combinations thereof.
Referring to fig. 2, a sacrificial film material 104 is formed over the first electrode 102. Next, a patterned photoresist 106 is formed over the sacrificial film material 104. In this embodiment, the sacrificial film material 104 may include a metal, an Oxide of a metal, or Indium Tin Oxide (ITO), wherein the metal is, for example, copper (Cu), titanium (Ti), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), molybdenum (Mo), tungsten (W). The patterned photoresist 106 is formed, for example, by forming a photoresist material layer (not shown) on the sacrificial film material 104, and performing a photolithography process on the photoresist material layer using the photomask 108 to form the patterned photoresist 106.
Then, an etching process is performed on the sacrificial film material 104 by 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, for example, by performing a photoresist removal (strip) process. In this embodiment, the thickness t0 of the sacrificial layer 104A is 500 angstrom
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, for example, silicon nitride (SiNx). In the present embodiment, the thickness t1 of the inorganic layer 110 is, for example, between 3000 a and 9000 a. Thus, the thickness t1 of the deposited (as-deposited) inorganic layer 110 is small enough to avoid warping (bonding) of the substrate 100. In this 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 lower oscillation portions 110A. For example, two upper holes TH1 may be formed. The upper hole TH1 is located at both sides of the lower oscillating portion 110A. In other words, the lower oscillating portion 110A is located between the upper holes TH1. And both ends of the sacrificial layer 104A are exposed through the upper holes TH1. 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, between 3000 angstroms and 9000 angstroms.
Referring to fig. 6, the sacrificial layer 104A is removed through 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, respectively. In this 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 the reliability of the subsequent process. For example, it may be 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 such that the size of the cavity CVT is affected, for example, the size of the cavity CVT is not reduced. The frequency of the ultrasonic waves that the transduction structure 10 is known to generate is inversely related to the size of the cavity CVT. That is, the larger the cavity CVT size, the lower the frequency, and the smaller the cavity CVT size, 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 a to 5500 a. For example, the thickness t2 of the first insulating portion 112B is at least 500 a greater than the height t00 of the cavity CVT (or the thickness t0 of the sacrificial layer 104A), for example, 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 this 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, for example, silicon nitride (SiNx). Thus, the upper oscillation portion 112A of the first insulating layer 112 and the lower oscillation portion 110A of the inorganic layer 110 may together form the oscillation film 114 of the transducer structure 10, and the thickness t2 of the deposited (as-reduced) first insulating layer 112 (e.g., the upper oscillation portion 112A and the first insulating portion 112B) is small enough to avoid the warpage (bonding) of the substrate 100, and, since the thickness t2 of the first insulating layer 112 is small enough and no etching process is required for the first insulating layer 112, the problem of thick film etching uniformity is avoided.
In this 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 is connected with the upper oscillating portion 112A, so that the sidewall portion 112C and each first insulating portion 112B together form the groove 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 so that the size of the cavity CVT is affected.
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 recess 112R formed by the sidewall portion 112C of the first insulating layer 112 and each first insulating portion 112B. The second insulating layer 116 is formed by spin coating (spin coating) method, for example. For example, the material of the second insulating layer 116 includes an organic material. In this 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 μm 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 TH1. In the present embodiment, each side wall portion 112C is located between the lower oscillating portion 110A and each second insulating portion 116A in the horizontal direction.
In this 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 (e.g., photoresist), and a photolithography process may be performed on the second insulating layer 116 by using the mask 118 to remove a portion of the second insulating layer 116, thereby forming the 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 part 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 transduction structure 10 are known to be related to the characteristics of the oscillating membrane 114. For example, the frequency of the ultrasonic wave and the thickness of the oscillation film 114 are positively correlated, and the stability of the ultrasonic wave and the surface flatness of the oscillation film 114 are positively correlated. 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. Thereby, the frequency of the ultrasonic wave provided by the oscillation film 114 constituted by the upper oscillation portion 112A and the lower oscillation portion 110A together 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 with the second insulating portions 116A, and the material of the second insulating portions 116A includes photoresist, the etching process of the second insulating portions 116, that is, the etching process, is omitted. The second insulating layer 116 is not required to be precisely etched, so that the risk of damage to the upper oscillating portion 112A caused by over etching of the upper oscillating portion 112A due to inaccurate etching is avoided, and the difficulty in manufacturing the transducer structure 10 is reduced.
Referring to fig. 10, a second electrode 120 is formed on the upper oscillating portion 112A, wherein a 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 a metal, such as aluminum, copper. In some embodiments, the second electrode 120 is formed by Chemical Vapor Deposition (CVD), physical Vapor Deposition (PVD), atomic Layer Deposition (ALD), evaporation (VTE), sputtering (SPT), or a combination thereof to deposit a metal material layer (not shown) over the entire surface, and then the second electrode 120 is formed by photolithography and etching processes. In this way, the transduction structure 10 of the present invention is completed. In the present embodiment, the transducing structure 10 is exemplified by capacitive mechanical ultrasonic sensing (capacitive micromachined ultrasonic transducer; CMUT). The first electrode 102 and the second electrode 120 serve as capacitors 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 receiving circuit (not shown) can be used to obtain a signal value by virtue of the change of the capacitance.
Fig. 11 is a perspective view of the transduction structure 10 of fig. 10. For convenience of explanation, fig. 11 shows a first direction D1 and a second direction D2, wherein the first direction D1 and the second direction D2 intersect. In the present embodiment, the first direction D1 is substantially perpendicular to the second direction D2, but the present invention is not limited thereto. Referring to fig. 11, the second electrode 120 extends along the 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 a curved probe (cone-probe). The ultrasonic probe 30 includes a housing 200, a transducer 20, an acoustic matching layer (acoustic matching layer) 202, a backing material (backing material) 204, an acoustic lens (acoustic lens) 206, and a cable (not shown). The backing material 204 may reduce the pulse duration and increase the 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 device 20 of fig. 12A. Fig. 12C is a schematic top view of a transducer device 20a according to another embodiment. Fig. 13 is a partial image of fig. 12B under an electron microscope. Fig. 14 is a cross-sectional image of fig. 12B along section line 14-14'. Fig. 15 is an enlarged schematic view of the region R of fig. 14, please refer to fig. 12B, 13, 14 and 15 together, wherein the transducer device 20 includes a plurality of transducer structures 10 and at least one circuit 122. The structure of the transducer structure 10 is as described above and will not be described herein. In this embodiment, the first electrode 102 is disposed on the substrate 100 in a whole surface. The second electrodes 120 are stripe-shaped in plan view and are arranged in an array at intervals along the second direction D2. The circuit 122 is located at one side of the transducer structure 10, wherein the first electrodes 102 of the transducer 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 device 20 further includes a circuit 124, wherein the second electrodes 120 of the transducer structure 10 are electrically connected to each other through the circuit 124. In this embodiment, the line 124 and the second electrode 120 are the same film.
Referring to fig. 14 and 15, it can be seen that the surface flatness of the oscillation film 114 is high, and the second insulating 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 in fig. 12C. In the present embodiment, the first electrodes 102a of each of the transducer structures 10 are separated from each other along at least the second direction D2, and the first electrodes 102a are arranged in an array along the second direction D2. In this embodiment, each of the first electrodes 102a has a stripe shape in a plan view. Thereby, the transduction device 20a can have high light transmittance.
Fig. 16-21 are schematic cross-sectional views of a manufacturing process of a transducer 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 a second electrode 120' is formed on the inorganic layer 110. The first electrode 102, the sacrificial layer 104A, and the inorganic layer 110 are formed by the same method and materials as those of the manufacturing process of fig. 1 to 4, and thus are not described herein. The second electrode 120 may be formed by Chemical Vapor Deposition (CVD), physical Vapor Deposition (PVD), atomic Layer Deposition (ALD), evaporation (VTE), sputtering (SPT), or a combination thereof to deposit a metal material layer (not shown) over the entire surface, and then the second electrode 120 is formed by photolithography and etching processes. For example, the material of the inorganic layer 110 is, for example, silicon nitride (SiNx). In the present embodiment, the thickness t1' of the inorganic layer 110 is, for example, between 3000 angstroms and 9000 angstroms. Thus, the thickness t1' of the deposited (as-deposited) inorganic layer 110 is small enough to avoid warping (bonding) of the substrate 100. In this 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 lower oscillating portions 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 TH1. And sacrificial layer 104A is exposed through upper hole TH1. 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 through the upper hole TH1 to form a plurality of lower holes TH2 respectively located below the upper hole TH1 and a receiving space SP located below the lower oscillating portion 110A. For example, two lower holes TH2 respectively located below the two upper holes TH1 may be formed. 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 portions 112B are respectively filled into the lower holes TH2 located below the upper holes TH1 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. 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. Thus, the upper oscillation portion 112A of the first insulating layer 112 and the lower oscillation portion 110A of the inorganic layer 110 may together constitute the oscillation film 114' of the transduction structure 10', and the thickness t2' of the deposited (as-reduced) first insulating layer 112 (e.g., the upper oscillation portion 112A and the first insulating portion 112B) is sufficiently small to avoid warpage (bonding) of the substrate 100. Moreover, since the thickness t2' of the first insulating layer 112 is small enough and the etching process of the first insulating layer 112 is not required, the problem of thick film etching uniformity is avoided.
In this embodiment, the first insulating layer 112 further includes a sidewall 112C, and the sidewall 112C is located on the sidewall SS of the upper hole TH1 of the inorganic layer 110, in other words, the sidewall 112C extends from the 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 recess 112R formed by the sidewall portion 112C of the first insulating layer 112 and each first insulating portion 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 this 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 TH1. In the present embodiment, each side wall portion 112C is located between the lower oscillating portion 110A and each second insulating portion 116A in the horizontal direction.
In this 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., photoresist), and a photolithography process may be performed on the second insulating layer 116 by using the mask 118 to remove a portion of the second insulating layer 116, thereby forming the 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 part 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 transduction structure 10 are known to be related to the characteristics of the oscillating membrane 114'. For example, the frequency of the ultrasonic wave and the thickness of the oscillation film 114 'are positively correlated, and the stability of the ultrasonic wave and the surface flatness of the oscillation film 114' are positively correlated. 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. Thereby, the frequency of the ultrasonic wave provided by the oscillation film 114' constituted by the upper oscillation section 112A and the lower oscillation section 110A together has high stability.
Since the upper holes TH1 of the inorganic layer 110 are respectively filled with the second insulating portions 116A, and the material of the second insulating portions 116A includes photoresist, the etching process of the second insulating portions 116, that is, the etching process, is omitted. The second insulating layer 116 does not need to be precisely etched, so that the risk of damage to the upper oscillating portion 112A caused by over etching of the upper oscillating portion 112A due to inaccurate etching is avoided, and the difficulty in manufacturing the transducer structure 10' is reduced.
In summary, since the material of the second insulating layer and the material of the first insulating portion are different, 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 by using a photomask to remove a portion of the second insulating layer, thereby forming the second insulating portion. Since the material of the second insulating layer and the material of the first insulating portion are different, the first insulating layer is not removed when a 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 the transduction 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 film formed by the upper oscillating part and the lower oscillating part has high stability, and the reliability of the oscillating film is improved.
Of course, the present invention is capable of other various embodiments and its several details are capable of modification and variation in light of the present invention, as will be apparent to those skilled in the art, without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A transduction 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 oscillating portion, a plurality of upper holes and a plurality of lower holes, the plurality of upper holes are located at two sides of the lower oscillating portion;
the first insulating layer comprises an upper oscillating part and a plurality of first insulating parts, wherein the upper oscillating part is positioned above the lower oscillating part, the plurality of first insulating parts are respectively filled in the plurality of lower holes and positioned on the first electrode, and the first electrode, the plurality of first insulating parts and the lower oscillating part form a cavity together;
the second insulation parts are respectively positioned on the first insulation parts, the second insulation parts are respectively contacted with the first insulation parts through the upper holes, and the materials of the second insulation parts are different from those of the first insulation parts; and
and a second electrode positioned on the upper oscillating portion, wherein the cavity is positioned between the first electrode and the second electrode.
2. The transduction structure of claim 1, wherein said plurality of second insulation 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 structure of claim 1, wherein the first insulating layer further comprises a sidewall portion on the sidewalls of the plurality of upper holes of the inorganic layer, such that the sidewall portion and each of the first insulating portions together form a recess.
5. A transducer apparatus, comprising:
a plurality of transduction structures according to any one of claims 1 to 4, wherein the first electrodes of each transduction structure are separated from each other at least in one direction, and each of the first electrodes is arranged in an array; and
the circuit is positioned at one side of the plurality of the transduction structures, wherein the first electrodes of the plurality of the transduction structures are electrically connected with each other through the circuit, and the circuit and the plurality of the first electrodes are the same film layer.
6. A method of manufacturing a transduction 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 plurality of upper holes are positioned on two sides of the lower oscillating portion, and the sacrificial layer is exposed through the plurality of upper holes;
removing the sacrificial layer to form a plurality of lower holes respectively positioned below the plurality of upper holes and a containing 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 the plurality of upper holes with a plurality of second insulating parts respectively, wherein the plurality of second insulating parts are respectively positioned on the plurality of first insulating parts, and the material of the plurality of second insulating parts comprises photoresist.
7. The method of manufacturing a transducer structure according to 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 manufacturing a transducer structure according to claim 7, 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 a to 5500 a.
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| TW109112131A TWI738290B (en) | 2020-04-10 | 2020-04-10 | Transducer apparatus、transducer structure and fabricating method thereof |
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| TWI738290B (en) | 2021-09-01 |
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