Ultrasonic transducer

Abstract

An ultrasonic transducer device includes a first electrode, an insulating layer, an oscillating membrane, a second electrode, and a third electrode. The insulating layer is disposed on the first electrode. The oscillating membrane is disposed on the insulating layer. A cavity is defined between the oscillating membrane and the insulating layer. The second electrode is disposed on the oscillating membrane. The third electrode is disposed within the cavity and has a plurality of first openings that overlap with the second electrode. The second and third electrodes are located on different sides of the oscillating membrane.

Description

Technical Field

[0001] The present invention relates to a transducer device, in particular to an ultrasonic transducer device. Background Art

[0002] Ultrasonic transducers are a technology that generates images by emitting and receiving ultrasonic waves. In everyday life, they can be used to measure distance, for example, by installing them in cars to assess driving distance, or in medical diagnosis to assess a patient's condition. Generally, ultrasonic transducers consist of multiple ultrasonic transducer cells. The cell density of an ultrasonic transducer affects its bandwidth and output power, and thus its performance. Improving the cell density of ultrasonic transducers is a current issue that requires improvement. Summary of the Invention

[0003] An object of the present invention is to provide an ultrasonic transducer device with an increased cell density, thereby improving the performance of the ultrasonic transducer device.

[0004] The ultrasonic transducer device of the present invention includes a first electrode, an insulating layer, an oscillating membrane, a second electrode, and a third electrode. The insulating layer is disposed on the first electrode. The oscillating membrane is disposed on the insulating layer, with a cavity defined between the oscillating membrane and the insulating layer. The second electrode is disposed on the oscillating membrane. The third electrode is disposed within the cavity and has a plurality of first openings that overlap the second electrode. The second and third electrodes are located on different sides of the oscillating membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1A FIG. 1 is a schematic top view of an ultrasonic transducer device according to an embodiment of the present invention.

[0006] Figure 1B and Figure 1C yes Figure 1A A schematic cross-sectional view of an ultrasonic transducer device along the section line AA'.

[0007] Figure 2 FIG. 4 is a schematic top view of an ultrasonic transducer device according to another embodiment of the present invention.

[0008] Figure 3 FIG. 4 is a schematic top view of an ultrasonic transducer device according to another embodiment of the present invention.

[0009] Figure 4 FIG. 4 is a schematic top view of an ultrasonic transducer device according to another embodiment of the present invention.

[0010] Figure 5 This is a schematic plan view of Comparative Example 1.

[0011] Figure 6 It is a schematic plan view of Comparative Example 2.

[0012] Figure 7 It is a schematic plan view of Comparative Example 3.

[0013] The reference numerals are as follows:

[0014] 10, 20, 30, 40: Ultrasonic transducer

[0015] 100,100': Ultrasonic transducer unit

[0016] 110: first electrode

[0017] 120: Insulation layer

[0018] 130: Cavity

[0019] 132: Sub-cavity

[0020] 140: Oscillating membrane

[0021] 140a: first surface

[0022] 140b: Second surface

[0023] 150: second electrode

[0024] 152: Main body

[0025] 154:Connection

[0026] 160: third electrode

[0027] 162: Longitudinal part

[0028] 164: Horizontal part

[0029] 170: Filling material

[0030] d1, d2: spacing

[0031] A-A': section line

[0032] D1: First direction

[0033] D2: Second direction

[0034] L: Length

[0035] OP1: First opening

[0036] OP2: Second opening

[0037] R1: Active Zone

[0038] R2: surrounding area

[0039] V:Through hole

[0040] W: width DETAILED DESCRIPTION

[0041] Figure 1A FIG. 1 is a schematic top view of an ultrasonic transducer device according to an embodiment of the present invention.

[0042] Figure 1B and Figure 1C yes Figure 1A A schematic cross-sectional view of an ultrasonic transducer device along the section line AA'.

[0043] Figure 1B FIG. 1 is a schematic cross-sectional view of the third electrode 160 in a state where no bias is applied. Figure 1C FIG is a cross-sectional view of the third electrode 160 when a bias voltage is applied. Figure 1A The oscillating film 140 is shown in a perspective manner, and the first electrode 110 and the insulating layer 120 are omitted.

[0044] Please refer to Figure 1A and Figure 1B The ultrasonic transducer device 10 includes a first electrode 110 , an insulating layer 120 , an oscillating membrane 140 , a second electrode 150 , and a third electrode 160 .

[0045] The materials of the first electrode 110, the second electrode 150, and the third electrode 160 can be titanium (Ti), aluminum (Al), copper (Cu), tungsten (W), molybdenum (Mo), silver (Ag), or alloys of the foregoing metals, or combinations of the foregoing metals, or other suitable conductive materials. In some embodiments, the first electrode 110, the second electrode 150, and the third electrode 160 can be a single layer or a multilayer structure (for example, a stacked structure of a titanium layer, an aluminum layer, and a titanium layer, respectively). In some embodiments, the materials of the first electrode 110, the second electrode 150, and the third electrode 160 can be the same or different, and the present invention is not limited thereto. In some embodiments, the first electrode 110 can be unpatterned and disposed entirely on a substrate (not shown).

[0046] The insulating layer 120 is disposed on the first electrode 110. The insulating layer 120 may be made of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, an organic insulating material, or other suitable insulating material, but the present invention is not limited thereto. In some embodiments, the insulating layer 120 is formed directly on and covers the first electrode 110. The area of ​​the insulating layer 120 may be the same as or different from the area of ​​the first electrode 110.

[0047] The oscillating film 140 is disposed on the insulating layer 120, with a cavity 130 defined between the oscillating film 140 and the insulating layer 120. In other words, at least a portion of the oscillating film 140 and the insulating layer 120 are not in direct contact. The oscillating film 140 is a thin film made of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, an organic insulating material, or other suitable thin film material. In some embodiments, the oscillating film 140 has a first surface 140a and a second surface 140b opposite the first surface 140a, with the second surface 140b facing the insulating layer 120.

[0048] The second electrode 150 and the third electrode 160 are located on different sides of the oscillating membrane 140. For example, the second electrode 150 is disposed on the first surface 140a of the oscillating membrane 140, and the third electrode 160 is disposed on the second surface 140b of the oscillating membrane 140. In other words, the third electrode 160 is disposed within the cavity 130. In some embodiments, the third electrode 160 has a mesh structure. For example, the third electrode 160 includes a plurality of longitudinal portions 162 extending in the second direction D2 and arranged along the first direction D1, and a plurality of transverse portions 164 extending in the first direction D1 and arranged along the second direction D2, wherein the first direction D1 intersects the second direction D2. In some embodiments, the first direction D1 is orthogonal to the second direction D2. The third electrode 160 has a plurality of first openings OP1, which are defined by the plurality of intersecting longitudinal portions 162 and transverse portions 164. In this embodiment, the first openings OP1 are square in shape, but the present invention is not limited thereto. In other embodiments, the first openings OP1 may be rectangular or another suitable shape.

[0049] The plurality of first openings OP1 overlap the second electrode 150. For example, the second electrode 150 may include a plurality of main portions 152 and a plurality of connecting portions 154. The area of ​​each main portion 152 is larger than the area of ​​each connecting portion 154. The plurality of main portions 152 are arranged in an array in the first direction D1 and the second direction D2, and overlap the first openings OP1 of the third electrode 160. In some embodiments, the projection of the main portion 152 onto the insulating layer 120 is a square, but the present invention is not limited thereto. The plurality of connecting portions 154 may connect between adjacent main portions 152 in the first direction D1 and between adjacent main portions 152 in the second direction D2. In this way, the plurality of connecting portions 154 and the plurality of main portions 152 may form a plurality of second openings OP2. In this embodiment, the second openings OP2 are shaped like a cross, but the present invention is not limited thereto. In other embodiments, the second openings OP2 may be shaped like a rectangle, a circle, a zigzag, or other suitable shape.

[0050] In some embodiments, the oscillating membrane 140 has a plurality of through holes V, and the through holes V penetrate the oscillating membrane 140. The through holes V are etched holes provided during the manufacturing process of the ultrasonic transducer device 10 to form the cavity 130. For example, a method for forming the cavity 130 includes: forming a sacrificial layer (not shown) on the insulating layer 120; then forming the third electrode 160, the oscillating membrane 140, and the second electrode 150 on the sacrificial layer; forming a through hole V on the oscillating membrane 140 to expose the sacrificial layer; and finally etching the sacrificial layer through the through hole V to form the cavity 130. After the cavity 130 is formed, a filling material 170 can be filled into the through hole V to seal the cavity 130. The filling material 170 is connected to the insulating layer 120. In some embodiments, the filling material 170 includes, for example, cured photoresist, silicon-containing nitride, silicon-containing oxide, or other insulating materials.

[0051] Please refer to Figure 1A and Figure 1CWhen a bias is applied to the third electrode 160 (for example, a DC bias can be applied to the third electrode 160), a voltage difference is generated between the third electrode 160 and the first electrode 110, causing the third electrode 160 to move closer to the first electrode 110. After the third electrode 160 is in direct contact with the insulating layer 120, the third electrode 160, the insulating layer 120, and the oscillating membrane 140 form a plurality of sub-cavities 132, each of which is a closed space and separated from each other. In this way, the third electrode 160, the insulating layer 120, the oscillating membrane 140, and the plurality of sub-cavities 132 can form a plurality of arrayed ultrasonic transducer units 100. The plurality of ultrasonic transducer units 100 substantially correspond to the plurality of first openings OP1 of the third electrode 160, that is, the third electrode 160 can define the size of the ultrasonic transducer unit 100. The width W and length L of the ultrasonic transducer unit 100 are substantially equal to the width and length of the first opening OP1. In this embodiment, the width W and length L of the ultrasonic transducer unit 100 are the same, and the spacing d1 between adjacent ultrasonic transducer units 100 in the first direction D1 is the same as the spacing d2 between adjacent ultrasonic transducer units 100 in the second direction D2, but the present invention is not limited to this. The size of the ultrasonic transducer unit 100 and the spacing d1 and d2 in the first direction D1 and the second direction D2 can be adjusted according to actual needs. In this document, the spacing d1 refers to the distance between the centers of two adjacent ultrasonic transducer units in the first direction D1, and the spacing d2 refers to the distance between the centers of two adjacent ultrasonic transducer units in the second direction D2. When the third electrode 160 is biased, the ultrasonic transducer unit 100 is formed by forming a sub-cavity 132 between the insulating layer 120, the oscillating membrane 140, and the third electrode 160. Compared to other ultrasonic transducer devices in which adjacent sub-cavities are filled with materials, this embodiment can obtain smaller sub-cavities 132 by isolating the sub-cavities 132 through the third electrodes 160 , thereby increasing the unit density of the ultrasonic transducer unit 100 .

[0052] In some embodiments, the oscillating membrane 140 is wavy when a bias is applied to the third electrode 160 , wherein the crests of the oscillating membrane 140 may correspond to the sub-cavities 132 , and the troughs of the oscillating membrane 140 may correspond to the third electrode 160 .

[0053] In some embodiments, the ultrasonic transducer device 10 may have an active region R1 and a peripheral region R2 located outside the active region R1. The peripheral region R2 may surround the active region R1 or be located only on one side or multiple sides of the active region R1, and the present invention is not limited thereto. The ultrasonic transducer unit 100 is located in the active region R1 to sense (e.g., receive or transmit) ultrasonic signals, so the first electrode 110, the second electrode 150, and the third electrode 160 may be located in the active region R1. In some embodiments, some of the through holes V may be located in the peripheral region R2 so that the active region R1 has more space to arrange the ultrasonic transducer unit 100, thereby increasing the unit density of the ultrasonic transducer device 10. In some embodiments, some through-holes V may be located in the active region R1, with at least two first openings OP1 separating adjacent through-holes V. In other words, at least two ultrasonic transducer units 100 are disposed between adjacent through-holes V. Compared to other ultrasonic transducer devices that have through-holes between adjacent ultrasonic transducer units, this embodiment can reduce the number of through-holes V, thereby increasing the unit density of the ultrasonic transducer device 10. In some embodiments, the through-holes V located in the active region R1 correspond to the first openings OP1 of the third electrode 160.

[0054] In some embodiments, after applying a DC bias to the third electrode 160 , the ultrasonic transducer unit 100 may apply an AC bias to the second electrode 150 to cause the oscillating membrane 140 to oscillate back and forth, thereby emitting ultrasonic waves.

[0055] Figure 2 FIG. 1 is a schematic top view of an ultrasonic transducer device according to another embodiment of the present invention. It must be noted that Figure 2 The implementation examples follow Figures 1A to 1C The component numbers and partial contents of the embodiments are the same or similar components, and the description of the same technical contents is omitted. For the description of the omitted parts, please refer to the above embodiments and will not be repeated here.

[0056] Please refer to Figure 2 , Figure 2 The ultrasonic transducer 20 and Figure 1A The difference between the ultrasonic transducer device 10 and the ultrasonic transducer device 20 is that the second opening OP2 of the second electrode 150 is zigzag-shaped. Specifically, adjacent main body portions 152 in the second direction D2 can be connected by corresponding connecting portions 154, but adjacent main body portions 152 in the first direction D1 are not connected to each other. In other words, the second electrode 150 is not a continuous structure and is disconnected from each other in the first direction D1. Although this embodiment shows that the second electrode 150 is discontinuous in the first direction D1, this is not intended to limit the present invention. In other embodiments, the second electrode 150 may be discontinuous in the second direction D2 but continuous in the first direction D1.

[0057] In some embodiments, the first opening OP1 is in a rectangular shape, and the projection shape of the main body portion 152 on the insulating layer 120 is also in a rectangular shape.

[0058] Figure 3 FIG. 1 is a schematic top view of an ultrasonic transducer device according to another embodiment of the present invention. It must be noted that Figure 3 The implementation examples follow Figures 1A to 1C The component numbers and partial contents of the embodiments are the same or similar components, and the description of the same technical contents is omitted. For the description of the omitted parts, please refer to the above embodiments and will not be repeated here.

[0059] Please refer to Figure 3 , Figure 3 The ultrasonic transducer 30 and Figure 1A The difference between the ultrasonic transducer device 10 and the ultrasonic transducer device 30 is that the second opening OP2 of the second electrode 150 is rectangular in shape.

[0060] Figure 4 FIG. 1 is a schematic top view of an ultrasonic transducer device according to another embodiment of the present invention. It must be noted that Figure 4 The implementation examples follow Figures 1A to 1C The component numbers and partial contents of the embodiments are the same or similar components, and the description of the same technical contents is omitted. For the description of the omitted parts, please refer to the above embodiments and will not be repeated here.

[0061] Please refer to Figure 4 , Figure 4 The ultrasonic transducer device 40 and Figure 1A The difference between the ultrasonic transducer device 10 and the ultrasonic transducer device 40 is that the second opening OP2 of the second electrode 150 of the ultrasonic transducer device 40 is circular or elliptical in shape.

[0062] The following examples are given to verify the efficacy of the present invention, but the present invention is not limited to the following contents. It must be noted that, Figures 5 to 7 Comparative example follows Figures 1A to 1C The component numbers and partial contents of the embodiments are the same or similar components, and the description of the same technical contents is omitted. For the description of the omitted parts, please refer to the above embodiments and will not be repeated here.

[0063] The following Examples 1, 2 and Comparative Examples 1 to 3 compare the differences in cell density of ultrasonic transducer units caused by different configurations of ultrasonic transducer devices under the same overall area, namely, 300 μm in length and 4500 μm in width.

[0064] The ultrasonic transducer device of Example 1 is similar to Figures 1A to 1C The ultrasonic transducer device of embodiment 2 is similar to Figure 2 The ultrasonic transducer devices of Comparative Examples 1 to 3 all include a first electrode 110, an insulating layer 120, an oscillating membrane 140, and a second electrode 150, but do not have a third electrode. A cavity is provided between the oscillating membrane 140 and the insulating layer 120, and a filling material 170 is provided between adjacent ultrasonic transducer units 100'. However, the ultrasonic transducer units 100' and the filling material 170 of Comparative Examples 1 to 3 are arranged differently, as shown in FIG. Figures 5 to 7 shown.

[0065] The dimensions, number, area ratio, and unit density of the ultrasonic transducer units of Examples 1 and 2 and Comparative Examples 1 to 3 are listed in Table 1. The dimensions of the ultrasonic transducer units of Comparative Examples 1 to 3 in Table 1 refer to the width W and length L of the oscillating membrane 140 corresponding to the main body 152 of the second electrode 150. Spacings d1 and d2 refer to the distances between the centers of two adjacent ultrasonic transducer units 100 / 100' in the first direction D1 and the second direction D2, respectively. The area ratio refers to the ratio of the total area of ​​the ultrasonic transducer units to the overall area of ​​the active region R1 of the ultrasonic transducer device. The unit density is used to calculate the ratio of the area of ​​the ultrasonic transducer units to the area of ​​the through-holes. For example, in Comparative Examples 1 to 3, the number of ultrasonic transducer units is equal to the number of through-holes, so the unit density is (area of ​​one ultrasonic transducer unit) / (area of ​​one ultrasonic transducer unit + area of ​​one through-hole); in Examples 1 to 2, the number of ultrasonic transducer units is n times (e.g., 15 times) the number of through-holes, so the unit density is (area of ​​n ultrasonic transducer units) / (area of ​​n ultrasonic transducer units + area of ​​one through-hole).

[0066] Table 1

[0067]

[0068] Because the ultrasonic transducer units 100 of Examples 1 and 2 are constructed by forming a sub-cavity 132 between the insulating layer 120, the oscillating membrane 140, and the third electrode 160 when a bias voltage is applied to the third electrode 160, more ultrasonic transducer units 100 can be arranged within the same area, or the ultrasonic transducer units 100 occupy a higher area, resulting in a higher unit density, thereby improving the bandwidth and output power of the ultrasonic transducer device.

Claims

1. An ultrasonic transducer device comprising: a first electrode; an insulating layer disposed on the first electrode; an oscillating membrane disposed on the insulating layer, wherein a cavity is defined between the oscillating membrane and the insulating layer; a second electrode disposed on the oscillating membrane; as well as a third electrode with a mesh structure disposed in the cavity, the third electrode with a mesh structure having a plurality of first openings overlapping the second electrode, the second electrode and the third electrode with a mesh structure being located on different sides of the oscillating membrane and in contact with the oscillating membrane, the cavity being located between the third electrode with a mesh structure and the insulating layer, and the insulating layer being located between the cavity and the first electrode; When a bias voltage is applied to the third electrode with a mesh structure, the third electrode with a mesh structure is in direct contact with the insulating layer; the third electrode with a mesh structure, the insulating layer and the oscillating membrane constitute a plurality of sub-cavities to form a plurality of arrayed ultrasonic transducer units; after the bias voltage is applied to the third electrode with a mesh structure, the oscillating membrane becomes wavy, wherein the crests of the oscillating membrane correspond to the sub-cavities, and the troughs of the oscillating membrane correspond to the third electrode with a mesh structure. 2 . The ultrasonic transducer device as claimed in claim 1 , wherein the oscillation membrane has a plurality of through holes and a plurality of filling materials filled in the plurality of through holes, and adjacent through holes are separated by at least two of the plurality of first openings. 3 . The ultrasonic transducer device as claimed in claim 2 , wherein the ultrasonic transducer device has an active region and a peripheral region located outside the active region, wherein the third electrode is located in the active region, and part of the plurality of through holes is located in the peripheral region. 4 . The ultrasonic transducer device as claimed in claim 1 , wherein the second electrode has a plurality of second openings, and the shapes of the second openings include a cross, a rectangle, a circle, or a sawtooth. 5 . The ultrasonic transducer device according to claim 1 , wherein the second electrode comprises a plurality of main bodies and a plurality of connecting parts, the plurality of main bodies overlap the plurality of first openings, and the plurality of connecting parts connect adjacent ones of the plurality of main bodies.

6. The ultrasonic transducer device as claimed in claim 5, wherein a plurality of the main body portions adjacent to each other in a first direction are connected via a corresponding plurality of the connecting portions, and a plurality of the main body portions adjacent to each other in a second direction are not connected to each other, wherein the first direction intersects the second direction.

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