Ultrasonic transducer element and ultrasonic transducer device

Abstract

An ultrasonic transducer element and an ultrasonic transducer device are provided. The ultrasonic transducer element includes a substrate, a first lower electrode, a first insulating layer, a second insulating layer, a second lower electrode, a first upper electrode, and a third insulating layer. The first lower electrode is disposed on the substrate. The first insulating layer is disposed such that the first lower electrode is between the first insulating layer and the substrate. The second insulating layer forms a first cavity with the first insulating layer, wherein the first cavity is between the first insulating layer and the second insulating layer. The first cavity includes a central region and an outer region. The second insulating layer has opposing first and second sides. The second lower electrode is disposed adjacent to the first side of the second insulating layer and in the outer region of the first cavity. The first upper electrode is disposed on the second side of the second insulating layer. The third insulating layer is disposed such that the second lower electrode is between the third insulating layer and the first insulating layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a transducer device, in particular to an ultrasonic resonator element and an ultrasonic transducer device. BACKGROUND

[0002] In the current development of ultrasonic transducers, it can be divided into bulk piezoelectric ceramics transducer, capacitive micromachined ultrasonic transducer (CMUT) and piezoelectric micromachined ultrasonic transducer (PMUT). However, in the future trend, since the micromachined ultrasonic transducer is prepared by microelectromechanical systems (MEMS) process, it has great process compatibility with integrated circuits, so it becomes the best implementation scheme of miniaturized ultrasonic system. Therefore, it can further realize large-scale preparation and packaging, and be applied in the fields of nondestructive testing, medical imaging, ultrasonic microscope, fingerprint recognition or Internet of Things. However, in the current capacitive micromachined ultrasonic transducer structure, how to increase the capacitance value to improve the transducer sensitivity is one of the goals of the development in the field.

[0003] Therefore, it is necessary to design a new ultrasonic resonator element and an ultrasonic transducer device to overcome the above defects. SUMMARY

[0004] The purpose of the present application is to provide an ultrasonic resonator element and an ultrasonic transducer device, which can greatly reduce the electrode spacing distance of the effective area, thereby increasing the capacitance, and greatly improving the working efficiency of the thin film.

[0005] To achieve the above purpose, the present application provides an ultrasonic resonator element, comprising: a substrate; a first lower electrode disposed on the substrate; a first insulating layer disposed such that the first lower electrode is located between the first insulating layer and the substrate; a second insulating layer forming a first cavity with the first insulating layer, wherein the first cavity is located between the first insulating layer and the second insulating layer, the first cavity includes a central region and an outer region, and the second insulating layer has opposite first and second sides; a second lower electrode disposed adjacent to the first side of the second insulating layer and located in the outer region of the first cavity; a first upper electrode disposed on the second side of the second insulating layer; and a third insulating layer disposed such that the second lower electrode is located between the third insulating layer and the first insulating layer.

[0006] Preferably, the first cavity is located between the first lower electrode and the second lower electrode.

[0007] Preferably, the first upper electrode comprises a first portion and a second portion, at least part of the first portion overlaps the central region of the first cavity in a stacking direction, and at least part of the second portion overlaps the outer region of the first cavity in the stacking direction.

[0008] Preferably, at least part of the first lower electrode overlaps the first portion of the first upper electrode in the stacking direction.

[0009] Preferably, at least part of the second lower electrode overlaps the second portion of the first upper electrode in the stacking direction.

[0010] Preferably, the first portion of the first upper electrode is driven by a direct current signal relative to the first lower electrode to cause the second insulating layer to be recessed toward the first cavity.

[0011] Preferably, the second portion of the first upper electrode is driven by an alternating current signal relative to the second lower electrode to generate vibration.

[0012] Preferably, the second lower electrode overlaps at least part of the first lower electrode in the stacking direction.

[0013] Preferably, further comprising: a fourth insulating layer disposed in the first cavity, wherein the second lower electrode is located between the second insulating layer and the fourth insulating layer.

[0014] Preferably, further comprising: a second upper electrode disposed such that the third insulating layer is located between the second upper electrode and the first upper electrode; and a fifth insulating layer disposed such that the second upper electrode is located between the fifth insulating layer and the third insulating layer.

[0015] Preferably, further comprising: a second cavity disposed between the second upper electrode and the first upper electrode.

[0016] Preferably, the second cavity is adjacent to either side of the third insulating layer or inside the third insulating layer.

[0017] The present application also provides an ultrasonic transducer device, characterized by comprising: a plurality of ultrasonic oscillation sub-elements as described above, arranged in an array.

[0018] Compared with the prior art, the ultrasonic oscillation element and the ultrasonic transducer device provided by the embodiment of the present application have the following advantages: the ultrasonic oscillation element comprises a substrate, a first lower electrode, a first insulating layer, a second insulating layer, a second lower electrode, a first upper electrode and a third insulating layer. The second insulating layer and the first insulating layer form a first cavity, and the first cavity comprises a central region and a lateral region. The first lower electrode is arranged on the substrate, and the second lower electrode is arranged on the second insulating layer and located in the lateral region of the first cavity, so that the first cavity is located between the first lower electrode and the second lower electrode. In this way, the electrode spacing distance of the effective region can be greatly reduced, and the capacitance can be increased, thereby greatly improving the working efficiency of the capacitive microelectromechanical ultrasonic transducer film. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a schematic diagram of an ultrasonic transducer device according to an embodiment of the present application.

[0020] Figure 2A FIG. 2 is a schematic diagram of a cross section of an ultrasonic oscillation element according to another embodiment of the present application.

[0021] Figure 2B FIG. 3 is a schematic diagram of the ultrasonic oscillation element of FIG. 2 performing oscillation. Figure 2A

[0022] Figure 3A FIG. 4 is a schematic diagram of a cross section of an ultrasonic oscillation element according to another embodiment of the present application. Figure 3B

[0023] FIG. 5 is a schematic diagram of the ultrasonic oscillation element of FIG. 4 performing oscillation. Figure 4A

[0024] FIG. 6 is a schematic diagram of a cross section of an ultrasonic oscillation element according to another embodiment of the present application. Figure 4B Figure 4A FIG. 7 is a schematic diagram of the ultrasonic oscillation element of FIG. 6 performing oscillation.

[0025] Figure 5 FIG. 8 is a schematic diagram of a cross section of an ultrasonic oscillation element according to another embodiment of the present application.

[0026] Figure 6 FIG. 9 is a schematic diagram of the ultrasonic oscillation element of FIG. 8 performing oscillation.

[0027] Figure 7 FIG. 10 is a schematic diagram of a cross section of an ultrasonic oscillation element according to another embodiment of the present application.

[0028] Figure 8 FIG. 11 is a schematic diagram of the ultrasonic oscillation element of FIG. 10 performing oscillation.

[0029] Figure 9 FIG. 12 is a schematic diagram of a cross section of an ultrasonic oscillation element according to another embodiment of the present application.​​

[0030] Figure 10 A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application.

[0031] Figure 11 A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application.

[0032] Figure 12 A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application.

[0033] Figure 13 A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application. DETAILED DESCRIPTION

[0034] To further understand the purpose, structure, features and functions of the present application, the following embodiments are described in detail.

[0035] Figure 1 A schematic view of an ultrasonic transducer device according to an embodiment of the present application. Please refer to Figure 1 The present embodiment provides an ultrasonic transducer device 50, which includes a plurality of ultrasonic transducer elements 100, such as a capacitive micromachined ultrasonic transducer (CMUT), which can be applied to non-destructive testing, medical imaging, ultrasound microscopy, fingerprint recognition, or the Internet of Things, and the present application is not limited thereto. For example, the plurality of ultrasonic transducer elements 100 can be arranged in an array on a base 52 and disposed on the end side of a housing 54. However, the present application is not limited to the type and form of the ultrasonic transducer device 50.

[0036] Figure 2A A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application. Figure 2B A schematic view of an ultrasonic transducer element according to another embodiment of the present application. Please refer to Figure 2A Figure 2A Figure 2B The ultrasonic transducer element 100 shown in the present embodiment can be applied to at least Figure 1 ​​The ultrasonic transducer 50 is shown in the following description. The ultrasonic transducer 50 includes a substrate 110, a first lower electrode 120, a first insulating layer 130, a second insulating layer 140, a second lower electrode 150, a first upper electrode 160, and a third insulating layer 170. The first lower electrode 120 is disposed on the substrate 110. The first insulating layer 130 is disposed such that the first lower electrode 120 is located between the first insulating layer 130 and the substrate 110. The second insulating layer 140 and the first insulating layer 130 form a first cavity G1, wherein the first cavity G1 is located between the first insulating layer 130 and the second insulating layer 140. The first cavity G1 includes a central region G11 and an outer region G12. The second insulating layer 140 has a first side A1 and a second side A2 opposite to each other. The second lower electrode 150 is disposed adjacent to the first side A1 of the second insulating layer 140 and located in the outer region G12 of the first cavity G1. In the present embodiment, the first cavity G1 is located between the first lower electrode 120 and the second lower electrode 150, which is different from the conventional configuration design. In this way, the electrode spacing distance of the effective region can be greatly reduced, thereby increasing the capacitance and greatly improving the working efficiency of the capacitive micro-machined ultrasonic transducer film.

[0037] The first upper electrode 160 is disposed on the second side A2 of the second insulating layer 140. The third insulating layer 170 is disposed such that the second lower electrode 150 is located between the third insulating layer 170 and the first insulating layer 130. Specifically, in the present embodiment, the first upper electrode 160 includes a first portion 162 and a second portion 164, wherein at least part of the first portion 162 overlaps the central region G11 of the first cavity G1 in the stacking direction. At least part of the second portion 164 overlaps the outer region G12 of the first cavity G1 in the stacking direction. On the other hand, in the present embodiment, at least part of the first lower electrode 120 overlaps the first portion 162 of the first upper electrode 160 in the stacking direction. At least part of the second lower electrode 150 overlaps the second portion 164 of the first upper electrode 160 in the stacking direction. Therefore, in the present embodiment, different electrode portions of the ultrasonic transducer 100 can be operated by applying a direct current signal and an alternating current signal to the different electrode portions, respectively.

[0038] Specifically, when not in operation, the ultrasonic transducer 100 is not supplied with a direct current signal, and the structure appears as shown in Figure 2A When in operation, a direct current signal is first applied to the first lower electrode 120 and the first portion 162 of the first upper electrode 160, so that the first portion 162 of the first upper electrode 160 is driven by the direct current signal to generate a pulling effect relative to the first lower electrode 120, causing the second insulating layer 140, the second lower electrode 150, the first upper electrode 160, and the third insulating layer 170 to be recessed into the first cavity G1, and appear in a curved state, as shown in Figure 2BIn another aspect, an AC signal is applied to the second lower electrode 150 and the second portion 164 of the first upper electrode 160 to drive the second portion 164 of the first upper electrode 160 to vibrate relative to the second lower electrode 150. In other words, in this embodiment, the outer region G12 of the first cavity G1 is the main vibration region, and the thickness of the second insulating layer 140 between the second lower electrode 150 and the second portion 164 of the first upper electrode 160 is the working gap. In this way, the design of this embodiment can greatly reduce the electrode spacing distance of the effective region (e.g., reduce the electrode spacing distance of the effective region to half of that of the conventional structure), thereby increasing the capacitance, and thus greatly improving the working efficiency of the thin film.

[0039] Figure 3A and Figure 3B are cross-sectional views of ultrasonic resonator elements according to different embodiments of the present application. Please refer to Figure 3A . The ultrasonic resonator element 100A1 shown in this embodiment is similar to the ultrasonic resonator element 100 shown in Figure 2A . The difference between them is that, in this embodiment, the area of the first lower electrode 120A in the horizontal direction can be designed to increase, so that the second lower electrode 150 overlaps at least part of the first lower electrode 120A in the stacking direction. In this way, the quality of the signal can be improved due to the increased area of the ground electrode. Please refer to Figure 3B . In another embodiment, the area of the first lower electrode 120A of the ultrasonic resonator element 100A2 in the horizontal direction can be designed to increase beyond the range of the second lower electrode 150 in the stacking direction, or even completely overlap the substrate 110 in the stacking direction. In this way, when the first lower electrode 120A is prepared, the first lower electrodes 120A of multiple ultrasonic resonator elements 100A2 can be electrically connected to increase the process convenience and electrical performance of the first lower electrode 120A, as shown in Figure 3B .

[0040] Figure 4A is a cross-sectional view of an ultrasonic resonator element according to another embodiment of the present application. Figure 4B is a schematic view of the ultrasonic resonator element shown in Figure 4A vibrating. Please refer to Figure 4A and Figure 4B . The ultrasonic resonator element 100B shown in this embodiment is similar to the ultrasonic resonator element 100 shown in Figure 2A and Figure 2BThe ultrasonic transducer element 100B shown in this embodiment is similar to the ultrasonic transducer element 100 shown in FIG. 1, except that in this embodiment, the ultrasonic transducer element 100B further comprises a fourth insulating layer 180 disposed in the first cavity G1, wherein the second lower electrode 150 is located between the second insulating layer 140 and the fourth insulating layer 180. In this way, the manufacturing difficulty can be simplified, thereby improving the manufacturing yield of the ultrasonic transducer element 100B.

[0041] Figure 5 A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application is shown in FIG. 2. Please refer to FIG. 2. Figure 5 The ultrasonic transducer element 100C shown in this embodiment is similar to the ultrasonic transducer element 100 shown in FIG. 1, except that in this embodiment, the area of the first lower electrode 120A in the horizontal direction is designed to be increased, so that the second lower electrode 150 overlaps at least part of the first lower electrode 120A in the stacking direction. In this way, the signal quality can be improved due to the increased area of the ground electrode. In another embodiment, the area of the first lower electrode 120A in the horizontal direction can be designed to be increased to beyond the range of the second lower electrode 150 in the stacking direction, or even to completely overlap the substrate 110 in the stacking direction (not shown). Figure 4A

[0042] A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application is shown in FIG. 3. Please refer to FIG. 3. Figure 6 The ultrasonic transducer element 100D shown in this embodiment is similar to the ultrasonic transducer element 100 shown in FIG. 1, except that in this embodiment, the ultrasonic transducer element 100D further comprises a second upper electrode 190 and a fifth insulating layer 200. Specifically, the second upper electrode 190 is disposed such that the third insulating layer 170 is located between the second upper electrode 190 and the first upper electrode 160. The fifth insulating layer 200 is disposed such that the second upper electrode 190 is located between the fifth insulating layer 200 and the third insulating layer 170. In this way, a dual upper electrode transducer structure can be formed, thereby improving the sensing sensitivity. Figure 6 Figure 2A A cross-sectional view of an ultrasonic transducer element according to another embodiment of the present application is shown in FIG. 4. Please refer to FIG. 4.

[0043] The ultrasonic transducer element 100E shown in this embodiment is similar to the ultrasonic transducer element 100 shown in FIG. 1, except that in this embodiment, the ultrasonic transducer element 100E further comprises a second upper electrode 190 and a fifth insulating layer 200. Specifically, the second upper electrode 190 is disposed such that the third insulating layer 170 is located between the second upper electrode 190 and the first upper electrode 160. The fifth insulating layer 200 is disposed such that the second upper electrode 190 is located between the fifth insulating layer 200 and the third insulating layer 170. In this way, a dual upper electrode transducer structure can be formed, thereby improving the sensing sensitivity. Figure 7 Figure 7 Figure 6 ​​The ultrasonic oscillator sub-element 100D is shown. The difference lies in that, in this embodiment, the area of ​​the first lower electrode 120A in the horizontal direction can be increased, such that the second lower electrode 150 overlaps at least partially with the first lower electrode 120A in the stacking direction. This increases the signal quality due to the increased area of ​​the ground electrode. In another embodiment, the area of ​​the first lower electrode 120A in the horizontal direction can be further increased beyond the area of ​​the second lower electrode 150 in the stacking direction, even completely overlapping the substrate 110 in the stacking direction (not shown).

[0044] Figure 8 This is a cross-sectional schematic diagram of an ultrasonic oscillating sub-element according to another embodiment of the present invention. Please refer to... Figure 8 The ultrasonic oscillating sub-element 100F shown in this embodiment is similar to... Figure 6 The ultrasonic oscillating sub-element 100D is shown. The difference between the two is that, in this embodiment, the ultrasonic oscillating sub-element 100F further includes a fourth insulating layer 180 disposed in the first cavity G1, wherein the second lower electrode 150 is located between the second insulating layer 140 and the fourth insulating layer 180. This simplifies the manufacturing process and improves the manufacturing yield of the ultrasonic oscillating sub-element 100F.

[0045] Figure 9 This is a cross-sectional schematic diagram of an ultrasonic oscillating sub-element according to another embodiment of the present invention. Please refer to... Figure 9 The ultrasonic oscillating sub-element 100G shown in this embodiment is similar to... Figure 8 The ultrasonic oscillator sub-element 100F is shown. The difference lies in that, in this embodiment, the area of ​​the first lower electrode 120A in the horizontal direction can be increased, such that the second lower electrode 150 overlaps at least partially with the first lower electrode 120A in the stacking direction. This increases the signal quality due to the increased area of ​​the ground electrode. In another embodiment, the area of ​​the first lower electrode 120A in the horizontal direction can be further increased beyond the area of ​​the second lower electrode 150 in the stacking direction, even completely overlapping the substrate 110 in the stacking direction (not shown).

[0046] Figure 10 This is a cross-sectional schematic diagram of an ultrasonic oscillating sub-element according to another embodiment of the present invention. Please refer to... Figure 10 The ultrasonic oscillating sub-element 100H shown in this embodiment is similar to... Figure 6The ultrasonic transducer element 100D is shown. The difference between the two is that, in the present embodiment, the ultrasonic transducer element 100H further comprises a second cavity G2, which is disposed between the second upper electrode and the first upper electrode. Specifically, the second cavity G2 is disposed inside the third insulating layer 170. However, in different embodiments, the second cavity G2 can also be designed to be adjacently disposed on any side of the third insulating layer 170 (not shown), and the present application is not limited thereto. In this way, the sensing sensitivity can be further improved.

[0047] Figure 11 The cross-sectional view of the ultrasonic transducer element of another embodiment of the present application is shown. Please refer to Figure 11 The ultrasonic transducer element 100I shown in the present embodiment is similar to Figure 10 The ultrasonic transducer element 100H shown. The difference between the two is that, in the present embodiment, the area of the first lower electrode 120A in the horizontal direction can be designed to be increased, so that the second lower electrode 150 overlaps at least part of the first lower electrode 120A in the stacking direction. In this way, due to the increase in the area of the ground electrode, the quality of the signal can be improved. In another embodiment, the area of the first lower electrode 120A in the horizontal direction can also be designed to be increased to exceed the range of the second lower electrode 150 in the stacking direction, or even completely overlap the substrate 110 in the stacking direction (not shown).

[0048] Figure 12 The cross-sectional view of the ultrasonic transducer element of another embodiment of the present application is shown. Please refer to Figure 12 The ultrasonic transducer element 100J shown in the present embodiment is similar to Figure 10 The ultrasonic transducer element 100H shown. The difference between the two is that, in the present embodiment, the ultrasonic transducer element 100J further comprises a fourth insulating layer 180, which is disposed in the first cavity G1, and the second lower electrode 150 is located between the second insulating layer 140 and the fourth insulating layer 180. In this way, the process difficulty can be simplified, thereby improving the manufacturing yield of the ultrasonic transducer element 100J.

[0049] Figure 13 The cross-sectional view of the ultrasonic transducer element of another embodiment of the present application is shown. Please refer to Figure 13 The ultrasonic transducer element 100K shown in the present embodiment is similar to Figure 12The ultrasound transducer element 100J is shown. The difference between the two is that in the present embodiment, the area of the first lower electrode 120A in the horizontal direction can be designed to increase, and the second lower electrode 150 can be designed to overlap at least part of the first lower electrode 120A in the stacking direction. In this way, the quality of the signal can be increased due to the increased area of the ground electrode. In another embodiment, the area of the first lower electrode 120A in the horizontal direction can be designed to increase beyond the range of the second lower electrode 150 in the stacking direction, and even to completely overlap the substrate 110 in the stacking direction (not shown).

[0050] In summary, in the ultrasound transducer element and the ultrasound transducer device of the present application, the ultrasound transducer element includes a substrate, a first lower electrode, a first insulating layer, a second insulating layer, a second lower electrode, a first upper electrode, and a third insulating layer. The second insulating layer and the first insulating layer form a first cavity, and the first cavity includes a central region and an outer region. The first lower electrode is disposed on the substrate, and the second lower electrode is disposed adjacent to the second insulating layer and located in the outer region of the first cavity, so that the first cavity is located between the first lower electrode and the second lower electrode. In this way, the electrode spacing distance of the effective region can be greatly reduced, and the capacitance can be increased, thereby greatly improving the working efficiency of the capacitive microelectromechanical ultrasound transducer film.

[0051] Although the present application has been described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to be illustrative of the preferred embodiments of the present application and are not understood to limit the present application. The proportions in the schematic drawings are not intended to represent the actual proportions of the components.

[0052] The present application has been described by the above-mentioned related embodiments, however the above-mentioned embodiments are only examples of implementing the present application. It must be pointed out that the disclosed embodiments do not limit the scope of the present application. On the contrary, modifications and improvements made without departing from the spirit and scope of the present application are within the scope of the patent protection of the present application.

Claims

1. An ultrasonic resonator element, characterized by comprising: Comprising: a substrate; a first lower electrode disposed on the substrate; a first insulating layer disposed such that the first lower electrode is between the first insulating layer and the substrate; a second insulating layer forming a first cavity with the first insulating layer, wherein the first cavity is between the first insulating layer and the second insulating layer, the first cavity comprises a central region and a lateral region, the second insulating layer has opposite first and second sides; a second lower electrode disposed on the first side of the second insulating layer and in the lateral region of the first cavity; a first upper electrode disposed on the second side of the second insulating layer; and a third insulating layer disposed such that the second lower electrode is between the third insulating layer and the first insulating layer. The first cavity is between the first lower electrode and the second lower electrode.

2. The ultrasonic resonator element of claim 1, wherein, The first upper electrode comprises a first portion and a second portion, at least part of the first portion overlaps the central region of the first cavity in a stacking direction, and at least part of the second portion overlaps the lateral region of the first cavity in the stacking direction.

3. The ultrasonic resonator element of claim 1, wherein At least part of the first lower electrode overlaps the first portion of the first upper electrode in the stacking direction.

4. The ultrasonic resonator element of claim 3, wherein, At least part of the second lower electrode overlaps the second portion of the first upper electrode in the stacking direction.

5. The ultrasonic resonator element of claim 3, wherein, The first portion of the first upper electrode is driven by a direct current signal relative to the first lower electrode to cause the second insulating layer to recess into the first cavity.

6. The ultrasonic resonator element of claim 3, wherein, The second portion of the first upper electrode is driven by an alternating current signal relative to the second lower electrode to generate vibration.

7. The ultrasonic resonator element of claim 3, wherein the piezoelectric layer is formed of a piezoelectric material having a piezoelectric constant d33 of 3000 pC / N or more. The second lower electrode overlaps at least part of the first lower electrode in the stacking direction.

8. The ultrasonic resonator element of claim 1 wherein, Further comprising:

9. The ultrasonic resonator element of claim 1 wherein, a fourth insulating layer disposed in the first cavity, wherein the second lower electrode is between the second insulating layer and the fourth insulating layer. Further comprising:

10. The ultrasonic resonator element of claim 1 wherein, a second upper electrode disposed such that the third insulating layer is between the second upper electrode and the first upper electrode; and a fifth insulating layer disposed such that the second upper electrode is between the fifth insulating layer and the third insulating layer. Further comprising: a second cavity disposed between the second upper electrode and the first upper electrode.

11. The ultrasonic resonator element of claim 10, wherein, The second cavity is disposed adjacent to either side of the third insulating layer or inside the third insulating layer. Comprising:

12. The ultrasonic resonator element of claim 11, wherein, a plurality of ultrasonic oscillation sub-elements as claimed in any one of claims 1 to 12 arranged in an array.

13. An ultrasonic transducer device, characterized by ​ ​

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