Ultrasonic transduction device and manufacturing method thereof

Abstract

The invention provides an ultrasonic transducer and a manufacturing method thereof. The ultrasonic transducer comprises a substrate, an ultrasonic oscillation unit and an upper insulating layer, the ultrasonic oscillation unit is arranged on the substrate and used for emitting or receiving ultrasonic waves, and the ultrasonic waves have resonance frequency. The upper insulating layer covers the ultrasonic oscillation unit and has a film thickness, and the film thickness is in positive correlation with the resonant frequency.

Description

Technical Field

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

[0002] As medical technology advances with each passing day, ultrasound detection technology is becoming more and more mature. Generally speaking, ultrasound detection uses a probe that emits ultrasound signals to emit ultrasound signals below the skin. In addition, the probe uses the reflected ultrasound signals to determine the shape and position of objects that are invisible to the naked eye below the skin for various medical purposes.

[0003] In addition, as the ultrasonic image has a high quality requirement, the use of ultrasonic transducers to suppress side lobes has become a mainstream technology. For example, the thickness of the piezoelectric material of the ultrasonic transducer is changed to suppress the side lobes effect. Therefore, in order to improve the impact of the side lobe effect on the ultrasonic signal and image quality, it is necessary to change the component configuration of the ultrasonic transducer device to effectively transmit and receive ultrasonic signals.

[0004] Therefore, it is necessary to design a new type of ultrasonic transducer and a manufacturing method thereof to overcome the above-mentioned defects. Summary of the invention

[0005] The object of the present invention is to provide an ultrasonic transducer device and a manufacturing method thereof, which can improve the influence of the sidelobe effect on the ultrasonic signal and image quality so as to effectively transmit and receive ultrasonic signals.

[0006] To achieve the above-mentioned object, the present invention provides an ultrasonic transducer device, comprising: a substrate; an ultrasonic oscillation unit, which is arranged on the substrate, the ultrasonic oscillation unit is used to emit or receive ultrasonic waves, and the ultrasonic waves have a resonant frequency; and an upper insulating layer, which covers the ultrasonic oscillation unit, the upper insulating layer has a film thickness, and the film thickness is positively correlated with the resonant frequency.

[0007] Preferably, the ultrasonic vibration unit includes a first electrode layer, a first insulating layer, a second electrode layer, a second insulating layer and a cavity located between the first insulating layer and the second insulating layer, the first insulating layer and the second insulating layer are separated by a distance, and the first insulating layer and the second insulating layer are located between the first electrode layer and the second electrode layer.

[0008] Preferably, the film thickness is between 4500 angstroms and 9000 angstroms.

[0009] Preferably, the material of the upper insulating layer includes silicon nitride or silicon dioxide.

[0010] The present invention also provides an ultrasonic transducer device, comprising: a substrate; an ultrasonic oscillation sheet, which is arranged on the substrate, and the ultrasonic oscillation sheet includes a plurality of ultrasonic oscillation units arranged along an axial direction, and the plurality of ultrasonic oscillation units are used to emit a group of ultrasonic waves, and the group of ultrasonic waves has a group resonant frequency; and an upper insulating layer, which covers the plurality of ultrasonic oscillation units, and the upper insulating layer has a film thickness, and the film thickness is positively correlated with the group resonant frequency.

[0011] Preferably, each of the ultrasonic vibration units includes a first electrode layer, a first insulating layer, a second electrode layer, a second insulating layer and a cavity located between the first insulating layer and the second insulating layer, the first insulating layer and the second insulating layer are separated by a distance, and the first insulating layer and the second insulating layer are located between the first electrode layer and the second electrode layer.

[0012] Preferably, the material of the upper insulating layer includes silicon nitride or silicon dioxide.

[0013] Preferably, the film thickness decreases gradually from the center of the upper insulating layer toward both sides.

[0014] Preferably, the gradient of the film thickness corresponds to a Gaussian curve distribution or a Hanning curve distribution.

[0015] The present invention also provides a method for manufacturing an ultrasonic transducer device, comprising: forming a plurality of ultrasonic oscillation units on a substrate, wherein the plurality of ultrasonic oscillation units are arranged along an axial direction; and forming an upper insulating layer on the plurality of ultrasonic oscillation units, wherein the upper insulating layer has a film thickness, and the film thickness gradually decreases from the center of the upper insulating layer to both sides.

[0016] Preferably, the gradient of the film thickness corresponds to a Gaussian curve distribution or a Hanning curve distribution.

[0017] Compared with the prior art, an ultrasonic transducer device and a manufacturing method thereof provided in an embodiment of the present invention can change the film thickness (for example, reduce it from 9000 angstroms to 4500 angstroms) so that each ultrasonic oscillation unit in the ultrasonic oscillation sheet generates a different resonance frequency, thereby improving the influence of the sidelobe effect on the ultrasonic signal and image quality, thereby improving the resolution of the ultrasonic image. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of an ultrasonic probe according to an embodiment of the present invention is shown.

[0019] Figure 2 FIG. 4 is a cross-sectional schematic diagram of an ultrasonic transducer device according to an embodiment of the present invention.

[0020] Figure 3 FIG. 4 is a schematic diagram of an ultrasonic transducer device according to an embodiment of the present invention.

[0021] Figure 4A and Figure 4B Draw Figure 3 Schematic diagram of the upper insulating layer having different thicknesses.

[0022] Figure 5A and Figure 5B FIG. 4 is a schematic diagram showing a film thickness gradient of an upper insulating layer corresponding to a Gaussian curve distribution or a Hanning curve distribution according to an embodiment of the present invention.

[0023] Figure 6 A schematic diagram is shown of a method for manufacturing an ultrasonic transducer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to provide a further understanding of the purpose, structure, features and functions of the present invention, the following detailed description is given in conjunction with the embodiments.

[0025] Please refer to Figure 1 , which illustrates a schematic diagram of an ultrasonic probe 100 according to an embodiment of the present invention. The ultrasonic probe 100 includes a housing 102, an acoustic lens 104, and an ultrasonic transducer 106 and a signal transmission line 108 located in the housing 102. The acoustic lens 104 is disposed at the front end of the housing 102, the ultrasonic transducer 106 is used to emit or receive ultrasonic waves, and the signal transmission line 108 is used to transmit acoustic and electrical signals to the ultrasonic transducer 106 or to transmit the acoustic and electrical signals received by the ultrasonic transducer 106 back to the ultrasonic device. When the user uses the ultrasonic probe 100 to contact the user's skin, the ultrasonic probe 100 can emit ultrasonic signals or receive ultrasonic signals through the acoustic lens 104 at the front end of the housing 102, and transmit the electrical signals back to the ultrasonic device through the signal transmission line 108.

[0026] In one embodiment, the ultrasonic transducer 106 is, for example, a transducer formed by a plurality of capacitive micro-machined ultrasonic transducers (CMUTs). Compared with a conventional piezoelectric ultrasonic transducer, the bandwidth of the CMUT is increased by 30% and the contrast intensity, sharpness, and color saturation of the image are richer, so that the resolution of the image is greatly improved. In addition, the film layers of each ultrasonic oscillation unit 109 of the ultrasonic transducer 106 can be formed on a substrate through a semiconductor process. The semiconductor process includes a thin film deposition process, a lithography process, an etching process, and a cleaning process, wherein the thin film deposition process includes sequentially depositing a plurality of film layers on a substrate, the lithography process includes defining the pattern and shape of each film layer through a photoresist layer, so that each film layer is stacked at a predetermined position, the etching process includes removing excess film layers to form a cavity in the film layer or forming a groove, and the cleaning process includes removing the photoresist layer, etching liquid, and other solvents.

[0027] Please refer to Figure 2 , which is a partial cross-sectional schematic diagram of an ultrasonic transducer device 106 according to an embodiment of the present invention, only a single ultrasonic oscillator unit 109 is shown. The ultrasonic transducer device 106 includes a substrate 110 and an ultrasonic oscillator unit 109, which is also called an ultrasonic oscillator. The ultrasonic oscillator unit 109 is disposed on the substrate 110, and the ultrasonic oscillator unit 109 includes a first electrode layer 112, a first insulating layer 114, a second electrode layer 118, a second insulating layer 116, and a cavity 122 located between the first insulating layer 114 and the second insulating layer 116.

[0028] Although in Figure 2 Only a single ultrasonic oscillation unit 109 is shown in the figure, but it is conceivable that the ultrasonic oscillation unit 109 can be a one-dimensional array or a two-dimensional array of elements to form the ultrasonic transducer device 106. For example, a plurality of ultrasonic oscillation units 109 can extend along the first direction (X axis) and be electrically connected to each other to form a one-dimensional array of ultrasonic oscillation sheets 107 (such as Figure 3 Alternatively, a plurality of ultrasonic oscillation units 109 may extend along a vertical first direction (X axis) and a second direction (Y axis) and be electrically connected to each other to form a two-dimensional array of ultrasonic oscillation sheets 107. Figure 3 As shown, a plurality of ultrasonic oscillating pieces 107 may be arranged in a long axis direction (Y axis direction) to form a group of ultrasonic oscillating pieces 107 in a long strip shape, and each ultrasonic oscillating piece 107 may receive an alternating voltage AC and vibrate, so that an ultrasonic signal generates a resonance frequency in the cavity 122. In addition, each ultrasonic oscillating piece 107 may also receive an external sound pressure signal (such as an ultrasonic signal) and vibrate, so that the sound pressure signal generates a resonance frequency in the cavity 122.

[0029] In one embodiment, the first electrode layer 112, the first insulating layer 114, the second insulating layer 116 and the second electrode layer 118 are stacked in sequence from bottom to top. The first electrode layer 112 is formed on the substrate 110, the first insulating layer 114 covers the first electrode layer 112, the second insulating layer 116 covers the first insulating layer 114, and there is a cavity 122 between the first insulating layer 114 and the second insulating layer 116, so that the first insulating layer 114 and the second insulating layer 116 are separated by a distance D. The cavity 122 is, for example, a sacrificial layer pre-formed between the first insulating layer 114 and the second insulating layer 116. After the structure is stacked, the sacrificial layer is etched with an etching solution to form the cavity 122 between the first insulating layer 114 and the second insulating layer 116. Subsequently, the second electrode layer 118 is formed on the second insulating layer 116. In addition, in one embodiment, an upper insulating layer 120 may be formed on the second electrode layer 118 to protect the second electrode layer 118. The upper insulating layer 120 , the first insulating layer 114 and the second insulating layer 116 may be made of the same or different materials. The insulating layers may be formed of silicon oxide (eg SiO 2 ), nitride (eg SiN), oxynitride or any other appropriate dielectric insulating material.

[0030] In one embodiment, the cavity 122 of the ultrasonic oscillation unit 109 is located between the first electrode layer 112 and the second electrode layer 118. The first electrode layer 112 is, for example, a ground layer, and the second electrode layer 118 is, for example, a signal layer for receiving an alternating voltage AC and / or a direct voltage DC signal. For example, the second electrode layer 118 can be driven by a direct voltage relative to the first electrode layer 112 and recessed toward the first electrode layer 112, so that the first insulating layer 114 and the second insulating layer 116 are relatively close. Alternatively, the second electrode layer 118 can be driven by an alternating voltage AC or an external sound pressure relative to the first electrode layer 112 to generate vibrations, thereby generating an ultrasonic signal. The pulse period of the alternating voltage AC can determine the resonant frequency of the output ultrasonic signal to generate ultrasonic signals of different frequencies.

[0031] In one embodiment, the resonant frequency of the ultrasonic signal in the cavity 122 is related to the length and width of the cavity 122, the thickness of the second electrode layer 118, the second insulating layer 116 and the upper insulating layer 120, wherein the length and width of the cavity 122 is, for example, 40 microns*40 microns, the thickness of the second electrode layer 118 and the thickness of the second insulating layer 116 are, for example, between 1 micron and 2 microns, and the film thickness H of the upper insulating layer 120 is between 500 angstroms and 18000 angstroms, preferably between 4500 angstroms and 9000 angstroms, but the present invention is not limited thereto. In this embodiment, since the resonant frequency of the ultrasonic signal in the cavity 122 is related to the film thickness H of the upper insulating layer 120, the film thickness H of the upper insulating layer 120 can be changed to change the resonant frequency, thereby causing each ultrasonic oscillation unit 109 to generate a different resonant frequency.

[0032] Please refer to Figure 2 The upper insulating layer 120 covers the ultrasonic oscillation unit 109. The upper insulating layer 120 has a thickness H, for example, between 4500 angstroms and 9000 angstroms. The thickness H is positively correlated with the resonance frequency. Figure 3 The upper insulating layer 120 covers the ultrasonic oscillating sheets 107. Each ultrasonic oscillating sheet 107 includes a plurality of ultrasonic oscillating units 109 arranged along an axial direction (e.g., an X-axis). These ultrasonic oscillating units 109 are used to emit a group of ultrasonic waves. The group of ultrasonic waves has a group resonant frequency, for example, between 12.3 MHz and 8.2 MHz. The upper insulating layer 120 has a film thickness, for example, between 4500 angstroms and 9000 angstroms, and the film thickness is positively correlated with the group resonant frequency.

[0033] In one embodiment, the film thickness H of the upper insulating layer 120 can be gradually reduced from the center of the upper insulating layer 120 to both sides, that is, the film thickness H of the upper insulating layer 120 can be reduced from 9000 angstroms to 4500 angstroms, and the film thickness in the middle (H2, see Figure 4A ) corresponds to a higher resonance frequency, while the film thickness on both sides (H1, see Figure 4B ) is lower, and the corresponding resonance frequency is also lower. For example, when the film thickness H of the upper insulating layer 120 is 9000 angstroms, the corresponding resonance frequency of the ultrasound generated in the cavity 122 is, for example, 12.3 MHz; when the film thickness H of the upper insulating layer 120 is 4500 angstroms, the corresponding resonance frequency of the ultrasound generated in the cavity 122 is, for example, 8.2 MHz, but the present invention is not limited thereto.

[0034] In addition, please refer to Figure 3 , Figure 4A and Figure 4B ,in Figure 4A and Figure 4B Draw according to Figure 3Schematic diagram of the upper insulating layer 120 having different thicknesses. In the X-axis direction, the film thickness of the upper insulating layer 120 can gradually decrease in a gradient from the center of the ultrasonic oscillating piece 107 towards both sides. That is, the film thickness H1 of the upper insulating layer 120 in the regions on both sides of the ultrasonic oscillating piece 107 is less than the film thickness H2 of the upper insulating layer 120 in the central region of the ultrasonic oscillating piece 107, H1 < H2. Therefore, the relatively higher film thickness H2 of the upper insulating layer 120 in the central region of the ultrasonic oscillating piece 107 can correspond to a relatively higher generated resonance frequency, while the relatively lower film thickness H1 of the upper insulating layer 120 in the regions on both sides of the ultrasonic oscillating piece 107 can correspond to a relatively lower generated resonance frequency, so that each ultrasonic oscillating unit 109 in the ultrasonic oscillating piece 107 generates different resonance frequencies.

[0035] Please refer to Figure 5A and Figure 5B , which respectively show schematic diagrams of the film thickness of the upper insulating layer 120 corresponding to the Gaussian curve distribution 130 or the Hanning curve distribution 131. In an embodiment, both the Gaussian curve distribution and the Hanning curve distribution are bell-shaped curve distributions, which represent the relationship between the resonance frequency of the ultrasonic wave and the film thickness of the upper insulating layer 120. Different film thicknesses H correspond to different resonance frequencies. Therefore, the gradient distribution of the film thickness H of the upper insulating layer 120 can be set as the Gaussian curve distribution or the Hanning curve distribution, but it can also be set as other types of curve distributions.

[0036] Please refer to Figure 2 and Figure 6 , wherein Figure 6 shows a schematic diagram of the manufacturing method 100' of the ultrasonic transducer device 106 according to an embodiment of the present invention. First, step S10 is executed to form a plurality of ultrasonic oscillating units 109 on the substrate 110. These ultrasonic oscillating units 109 are arranged along the axial direction, and their configuration is as shown in Figure 3 , which will not be elaborated here. Then, step S12 is executed to form the upper insulating layer 120 on these ultrasonic oscillating units 109. The upper insulating layer 120 has a film thickness H, and the film thickness H gradually decreases from the center of the upper insulating layer 120 towards both sides, and its configuration is as shown in Figure 4A and Figure 4B .

[0037] In one embodiment, the upper insulating layer 120 can be formed at a predetermined position and have a predetermined film thickness H through a semiconductor process, and the semiconductor process includes a thin film deposition process, a lithography process, an etching process, and a cleaning process. The lithography process can also be called a photolithography process. The photolithography process can transfer all the patterns on the mask to the photoresist layer, and then remove part of the photoresist layer through development to define the pattern and shape of the desired film layer. The etching process includes dry etching, plasma etching, reactive ion etching, or inductively coupled plasma etching, etc., which are used to remove part of the surface material to form a film layer of different thicknesses. Preferably, the upper insulating layer 120 is formed through an anisotropic etching process. Dry etching, for example, bombards the surface of the film layer with positively charged ions to remove part of the material. Plasma etching, for example, dissociates the molecules of the reaction gas into ions reactive to the film material for etching. Reactive ion etching is a dry etching between sputtering etching and plasma etching, and has the advantages of both anisotropic etching and acceptable selective etching.

[0038] In one embodiment, the upper insulating layer 120 can be formed by the above-mentioned anisotropic etching process, wherein the pattern of the upper insulating layer 120 is determined by the transparency of the mask pattern in the yellow light process, or by the diffraction order of the mask pattern in the yellow light process, or by the exposure intensity of the phase shift mask in the yellow light process. Through the transparency of the mask in the yellow light process, the order of the diffraction pattern, or the exposure intensity of the phase shift mask, the gradient pattern of the upper insulating layer 120 can be achieved to correspond to the Gaussian curve distribution 130 and the Hanning curve distribution 131.

[0039] In summary, the ultrasonic transducer device and its manufacturing method provided by the present invention include a substrate, an ultrasonic oscillation unit and an upper insulating layer. The ultrasonic oscillation unit is disposed on the substrate. The ultrasonic oscillation unit is used to emit or receive ultrasonic waves, and the ultrasonic waves have a resonant frequency. The upper insulating layer covers the ultrasonic oscillation unit, and the upper insulating layer has a film thickness, and the film thickness is positively correlated with the resonant frequency. By changing the film thickness (for example, reducing it from 9000 angstroms to 4500 angstroms), each ultrasonic oscillation unit in the ultrasonic oscillation sheet generates a different resonant frequency, thereby improving the influence of the sidelobe effect on the ultrasonic signal and image quality, so as to improve the resolution of the ultrasonic image.

[0040] Although the present invention is described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to exemplify the preferred embodiments of the present invention and should not be construed as limiting the present invention. In order to clearly describe the required components, the proportions in the schematic drawings do not represent the proportional relationship of the actual components.

[0041] The present invention has been described by the above-mentioned relevant embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, changes and modifications made without departing from the spirit and scope of the present invention are all within the scope of patent protection of the present invention.

Claims

1. An ultrasonic transducer device, characterized in that: include: substrate; An ultrasonic oscillation unit is disposed on the substrate, and is used to emit or receive ultrasonic waves, wherein the ultrasonic waves have a resonance frequency; and The upper insulating layer covers the ultrasonic oscillation unit, and the upper insulating layer has a film thickness, and the film thickness is positively correlated with the resonance frequency.

2. The ultrasonic transducer device according to claim 1, characterized in that: The ultrasonic vibration unit includes a first electrode layer, a first insulating layer, a second electrode layer, a second insulating layer and a cavity between the first insulating layer and the second insulating layer. The first insulating layer and the second insulating layer are spaced apart, and the first insulating layer and the second insulating layer are located between the first electrode layer and the second electrode layer.

3. The ultrasonic transducer device according to claim 1, characterized in that: The film thickness is between 4500 angstroms and 9000 angstroms.

4. An ultrasonic transducer device, characterized in that: include: substrate; An ultrasonic oscillation sheet is disposed on the substrate, the ultrasonic oscillation sheet includes a plurality of ultrasonic oscillation units arranged along the axial direction, the plurality of ultrasonic oscillation units are used to emit a group of ultrasonic waves, the group of ultrasonic waves having a group resonant frequency; and The upper insulating layer covers the plurality of ultrasonic oscillation units, and the upper insulating layer has a film thickness, and the film thickness is positively correlated with the group of resonance frequencies.

5. The ultrasonic transducer device according to claim 4, characterized in that: Each of the ultrasonic vibration units includes a first electrode layer, a first insulating layer, a second electrode layer, a second insulating layer and a cavity between the first insulating layer and the second insulating layer. The first insulating layer and the second insulating layer are spaced apart, and the first insulating layer and the second insulating layer are located between the first electrode layer and the second electrode layer.

6. The ultrasonic transducer device according to claim 1 or 4, characterized in that: The material of the upper insulating layer includes silicon nitride or silicon dioxide.

7. The ultrasonic transducer device according to claim 4, characterized in that: The film thickness decreases gradually from the center of the upper insulating layer to both sides.

8. The ultrasonic transducer device according to claim 7, characterized in that: The gradient of the film thickness corresponds to a Gaussian curve distribution or a Hanning curve distribution.

9. A method for manufacturing an ultrasonic transducer, characterized in that: include: Forming a plurality of ultrasonic oscillation units on a substrate, wherein the plurality of ultrasonic oscillation units are arranged along an axial direction; as well as An upper insulating layer is formed on the plurality of ultrasonic oscillation units. The upper insulating layer has a film thickness, and the film thickness gradually decreases from the center of the upper insulating layer to both sides.

10. The method for manufacturing the ultrasonic transducer device according to claim 9, characterized in that: The gradient of the film thickness corresponds to a Gaussian curve distribution or a Hanning curve distribution.

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