TW202332090A - Transducer and manufacturing method thereof - Google Patents

Abstract

A transducer includes a substrate, a lower electrode arranged on the substrate, an insulating layer arranged on the lower electrode, a sacrificial pattern arranged on the insulating layer, and an oscillating membrane arranged on the sacrificial pattern. The oscillating membrane has through holes. In a top view of the transducer, the through holes of the oscillating membrane are respectively located on different sides of the sacrificial pattern. The upper electrodes are arranged on the oscillating membrane. The encapsulation layer includes sealing portions. The sealing portions are respectively disposed in the through holes of the oscillating membrane and extend to the insulating layer. The oscillating membrane, the sealing portions of the encapsulation layer, the sacrificial pattern and the insulating layer define sub-cavities, and the sacrificial pattern separates the sub-cavities. Moreover, a manufacturing method of the transducer is also provided.

Description

Transducer and manufacturing method thereof

The invention relates to a transducer and a manufacturing method thereof.

Ultrasonic transducers include bulk piezoelectric ceramic transducers, capacitive micromechanical ultrasonic transducers and piezoelectric micromechanical ultrasonic transducers. In recent years, many manufacturers and research institutes have invested in the development of capacitive micromachined ultrasonic transducers. This technology utilizes semiconductor manufacturing process to miniaturize the size of the ultrasonic transducer, which is easier to integrate into various products than traditional bulk piezoelectric materials.

The capacitive micromachined ultrasonic transducer includes a lower electrode, an oscillating membrane above the lower electrode and an upper electrode on the oscillating membrane, wherein a cavity exists between the lower electrode and the oscillating membrane. The electric field between the lower electrode and the upper electrode can make the oscillating membrane vibrate in the cavity, so that ultrasonic waves can be emitted.

At present, one of the ways to make the cavity is: firstly form a plurality of sacrificial blocks on the substrate, and then form an oscillating film to cover the multiple sacrificial blocks; after that, let the etching solution enter from a plurality of through holes in the oscillating film to Contacting multiple sacrificial blocks, thereby completely removing the multiple sacrificial blocks, and forming multiple cavities. However, in order to completely remove the sacrificial block to form multiple cavities, at least a plurality of through holes must be provided on both sides of each sacrificial block, and at least one through hole must be provided between two adjacent sacrificial blocks. The arrangement of multiple through holes must occupy a lot of area, which excludes the total area that can be provided with the cavity, resulting in an increase in the total area of the cavity. When the total area of the cavity cannot be increased, the sound pressure and bandwidth of the transducer will not be easily increased.

The invention provides a transducer with good performance.

The transducer of the present invention includes a substrate, a lower electrode arranged on the substrate, an insulating layer arranged on the lower electrode, a sacrificial pattern arranged on the insulating layer, and an oscillation film arranged on the sacrificial pattern. The oscillating membrane has a plurality of through holes. In the top view of the transducer, the multiple through holes of the vibrating membrane are respectively located on different sides of the sacrificial pattern. A plurality of upper electrodes are arranged on the vibrating membrane. The encapsulation layer includes a plurality of sealing parts. A plurality of sealing parts are respectively disposed in the plurality of through holes of the oscillation film, and extend to the insulating layer. The vibrating film, the sealing parts of the encapsulation layer, the sacrificial pattern and the insulating layer define a plurality of sub-cavities, and the sacrificial pattern separates the plurality of sub-cavities.

The manufacturing method of the transducer of the present invention includes: forming a first conductive layer on a substrate, wherein the first conductive layer includes a lower electrode; forming an insulating layer on the first conductive layer; forming a sacrificial material layer on the insulating layer, wherein the sacrificial The material layer includes a sacrificial block arranged on the upper electrode; an oscillating material film is formed to cover the sacrificial material layer; a second conductive layer is formed on the oscillating material film, wherein the second conductive layer includes a plurality of upper electrodes; A plurality of through holes are formed in the film, so that the oscillating material film forms an oscillating film, wherein the plurality of through holes respectively expose multiple places of the sacrificial block; allowing the etching solution to enter the plurality of through holes to remove the sacrificial regions corresponding to the plurality of through holes The inside of the sacrificial block is left in many places of the block, and the inside of the remaining sacrificial block is called a sacrificial pattern; an encapsulation layer is formed on the oscillating film, wherein the encapsulation layer includes a plurality of sealing parts, and the plurality of sealing parts are respectively The vibration film, the multiple sealing parts of the encapsulation layer, the sacrificial pattern and the insulating layer define multiple sub-cavities, and the sacrificial pattern separates the multiple sub-cavities.

In an embodiment of the present invention, in the top view of the above-mentioned transducer, the plurality of upper electrodes are respectively located on different sides of the sacrificial pattern.

In an embodiment of the present invention, in the top view of the above-mentioned transducer, a virtual straight line passes through a plurality of through holes of the oscillating membrane, one direction is substantially parallel to the virtual straight line, and the width of the sacrificial pattern in the direction varies with increases as it moves away from the virtual straight line.

In an embodiment of the present invention, the above-mentioned sacrificial pattern has opposite top and bottom surfaces, and the top and bottom surfaces of the sacrificial pattern directly contact the vibrating film and the insulating layer respectively.

In an embodiment of the present invention, the above-mentioned sacrificial pattern has a side surface connecting the vibrating film and the insulating layer, and the side surface includes a curved surface.

In an embodiment of the present invention, the mother cavity includes the above-mentioned multiple sub-cavities and sacrificial patterns; in the top view of the transducer, the mother cavity is roughly rhombus-shaped.

In an embodiment of the present invention, the different sides of the aforementioned sacrificial pattern include a first side, a second side, a third side and a fourth side that are different from each other, the first side is opposite to the second side, and the second side The third side is opposite to the fourth side. The above-mentioned multiple sub-cavities include a first sub-cavity, a second sub-cavity, a third sub-cavity and a fourth sub-cavity respectively located on the first side, the second side, the third side and the fourth side of the sacrificial pattern cavity.

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 descriptions to refer to the same or like parts.

It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element, or Intermediate elements may also be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connected" may refer to physical and/or electrical connection. Furthermore, "electrically connected" or "coupled" may mean that other elements exist between two elements.

As used herein, "about," "approximately," or "substantially" includes stated values and averages within acceptable deviations from a particular value as determined by one of ordinary skill in the art, taking into account the measurements in question and the relative A specific amount of measurement-related error (ie, the limit of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, "about", "approximately" or "substantially" used herein can select a more acceptable deviation range or standard deviation according to optical properties, etching properties or other properties, and it is not necessary to use one standard deviation to apply to all properties .

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted to have meanings consistent with their meanings in the context of the relevant art and the present invention, and will not be interpreted as idealized or excessive formal meaning, unless expressly so defined herein.

1A to 1H are schematic cross-sectional views of the manufacturing process of a transducer according to an embodiment of the present invention. FIG. 2 is a schematic top view and perspective view of a transducer according to an embodiment of the present invention. 1A to 1H correspond to the section line I-I' of FIG. 2 . FIG. 2 shows the substrate 110 , the sacrificial pattern 142 , the vibrating film 150 and the second conductive layer 160 of the transducer 10 , while omitting other components of the transducer 10 .

Please refer to FIG. 1A , firstly, a substrate 110 is provided. In this embodiment, the material of the substrate 110 is glass, for example. However, the present invention is not limited thereto. In other embodiments, the material of the substrate 110 may also be quartz, organic polymer or other applicable materials.

Next, a first conductive layer 120 is formed on the substrate 110 , wherein the first conductive layer 120 includes a lower electrode 122 . In this embodiment, the first conductive layer 120 may selectively cover the entire substrate 110 , and the lower electrode 122 may be a region of the first conductive layer 120 , but the invention is not limited thereto. In this embodiment, the first conductive layer 120 includes, for example, a stacked layer of titanium/aluminum/titanium (Ti/Al/Ti). However, the present invention is not limited thereto, and in other embodiments, the first conductive layer 120 may also include other types of conductive materials. In addition, the present invention does not limit the first conductive layer 120 to include multiple stacked layers of conductive materials. In other embodiments, the first conductive layer 120 may also include a single conductive material.

Referring to FIG. 1B , next, an insulating layer 130 is formed on the first conductive layer 120 . In this embodiment, the insulating layer 130 may selectively cover the first conductive layer 120 completely, but the invention is not limited thereto. In this embodiment, the material of the insulating layer 130 can be an inorganic material (such as silicon nitride, silicon oxide, silicon oxynitride, or a stacked layer of at least two of the above materials), an organic material, or a combination thereof.

Referring to FIG. 1C, then, a sacrificial material layer 140' is formed on the insulating layer 130, wherein the sacrificial material layer 140' includes a sacrificial region 142' disposed above the lower electrode 122. Referring to FIG. For example, in this embodiment, the material of the sacrificial material layer 140' may be molybdenum (Mo). However, the present invention is not limited thereto, and in other embodiments, the material of the sacrificial material layer 140' may also be other types of materials.

Referring to FIG. 1D , next, an oscillating material film 150' is formed to cover the sacrificial material layer 140'. In this embodiment, the material of the oscillating material film 150' can be an inorganic material (such as silicon nitride, silicon oxide, silicon oxynitride, or a stacked layer of at least two of the above materials), an organic material, or a combination thereof.

Referring to FIG. 1E , next, a second conductive layer 160 is formed on the oscillating material film 150', wherein the second conductive layer 160 includes a plurality of upper electrodes 162. Referring to FIG. A plurality of upper electrodes 162 are located above the sacrificial region 142'. For example, in this embodiment, the second conductive layer 160 includes a stacked layer of molybdenum/aluminum/molybdenum (Mo/Al/Mo). However, the present invention is not limited thereto, and in other embodiments, the second conductive layer 160 may also include other types of conductive materials. In addition, the present invention does not limit the second conductive layer 160 to include stacked layers of multiple conductive materials. In other embodiments, the second conductive layer 160 may also include a single conductive material.

1E and FIG. 1F, then, form a plurality of through holes 152 in the oscillating material film 150', so that the oscillating material film 150' forms the oscillating film 150, wherein the plurality of through holes 152 respectively expose the sacrificial block 142' Lots of 142'-1. The sacrificial block 142' not only includes a plurality of locations 142'-1 corresponding to the plurality of through holes 152, but also includes an inner portion 142'-2 between the plurality of locations 142'-1.

Please refer to FIG. 1F and FIG. 1G , and then, make the etchant EL enter the plurality of through holes 152 to remove the multiple locations 142'-1 of the sacrificial block 142' corresponding to the plurality of through holes 152, and leave the sacrificial block 142' The inner portion 142 ′-2 of the sacrificial block 142 ′ can also be called the sacrificial pattern 142 .

Please refer to FIG. 1H , and then, an encapsulation layer 170 is formed on the oscillating film 150, wherein the encapsulation layer 170 includes a plurality of sealing portions 172, and the plurality of sealing portions 172 are respectively arranged in a plurality of through holes 152 of the oscillating film 150 and extend to the insulating layer 130. Here, the transducer 10 of this embodiment is completed. In this embodiment, the material of the encapsulation layer 170 can be an inorganic material (such as silicon nitride, silicon oxide, silicon oxynitride, or a stacked layer of at least two of the above materials), an organic material, or a combination thereof.

1H and FIG. 2, the transducer 10 includes a substrate 110, a lower electrode 122 disposed on the substrate 110, an insulating layer 130 disposed on the lower electrode 122, a sacrificial pattern 142 disposed on the insulating layer 130, and a The vibrating film 150 on the sacrificial pattern 142 , the plurality of upper electrodes 162 disposed on the vibrating film 150 , and the packaging layer 170 disposed on the vibrating film 150 . The vibrating membrane 150 has a plurality of through holes 152 . In the top view of the transducer 10 , the through holes 152 of the vibrating membrane 150 are respectively located on different sides of the sacrificial pattern 142 . The encapsulation layer 170 includes a plurality of sealing portions 172 , wherein the plurality of sealing portions 172 are respectively disposed in the plurality of through holes 152 of the oscillation film 150 and extend to the insulating layer 130 .

Please refer to FIG. 1H and FIG. 2, in particular, the vibrating film 150, the plurality of sealing portions 172 of the encapsulation layer 170, the sacrificial patterns 142 and the insulating layer 130 define a plurality of sub-cavities c of the transducer 10, wherein the sacrificial patterns 142 separate A plurality of sub-cavities c. Each working element E may include a sub-cavity c, a part of the vibrating membrane 150 defining the sub-cavity c, an upper electrode 162 overlapping the sub-cavity c, and a part of the lower electrode 122 .

Please refer to FIG. 1F to FIG. 1H and FIG. 2, in detail, at least a part of the space originally occupied by the sacrificial block 142' (refer to FIG. When sacrificing the area 142', by controlling the wet etching process time, part of the sacrificial area 142' (that is, the sacrificial pattern 142) can be left between the oscillation film 150 and the insulating layer 130, and the remaining part of the sacrificial area 142 ′ (ie, the sacrificial pattern 142 ) can divide the single unit cell region into a plurality of sub-cavities c. In this way, the same or more sub-cavities c can be produced with a smaller number of through holes 152 . Since the number of through-holes 152 to be provided is small, more space can be released for setting more working elements E, thereby increasing the sound pressure and bandwidth of the transducer 10 .

Referring to FIG. 2 , in this embodiment, in the top view of the transducer 10 , the plurality of upper electrodes 162 are located on different sides of the sacrificial pattern 142 . For example, in this embodiment, the plurality of upper electrodes 162 can be respectively located on the left and right sides of the sacrificial pattern 142 , but the invention is not limited thereto.

Please refer to FIG. 2. In this embodiment, in the top view of the transducer 10, a virtual straight line L passes through a plurality of through holes 152 of the vibrating film 150, the direction x is substantially parallel to the virtual straight line L, and the sacrificial pattern 142 is The width W in the direction x increases away from the virtual straight line L. As shown in FIG. In detail, in this embodiment, the sacrificial pattern 142 is a part of the sacrificial block 142 ′ left in the wet etching process, and the entrance of the etchant EL in the wet etching process is the through hole 152. The wet etching process is In the isotropic etching process, part of the sacrificial area 142 ′ in the etching range R with the through hole 152 as the center will be removed. Therefore, the width W of the remaining sacrificial pattern 142 in the direction x decreases as it moves away from the virtual straight line L. Increase.

Referring to FIG. 1F and FIG. 2 , the sacrificial pattern 142 has a top surface 142 a and a bottom surface 142 b opposite to each other, and a side surface 142 c connecting the top surface 142 a and the bottom surface 142 b. In this embodiment, the top surface 142 a and the bottom surface 142 b of the sacrificial pattern 142 directly contact the vibrating film 150 and the insulating layer 130 respectively. In this embodiment, the side surface 142c of the sacrificial pattern 142 includes a curved surface. In detail, in this embodiment, the side surface 142c of the sacrificial pattern 142 includes a concave curved surface.

It must be noted here that the following embodiments use the component numbers and part of the content of the previous embodiments, wherein the same numbers are used to denote the same or similar components, and descriptions of the same technical content are omitted. For the description of omitted parts, reference may be made to the aforementioned embodiments, and the following embodiments will not be repeated.

FIG. 3 is a schematic top view and perspective view of a transducer according to another embodiment of the present invention. Fig. 4 is a schematic cross-sectional view of a transducer according to another embodiment of the present invention. Fig. 4 corresponds to the section line II-II' of Fig. 3 . FIG. 3 shows the substrate 110 , the sacrificial pattern 142 , the vibrating film 150 and the second conductive layer 160 of the transducer 10A, while omitting other components of the transducer 10A.

The transducer 10A in FIG. 3 and FIG. 4 is similar to the transducer 10 in FIG. 1H and FIG. 2 , the difference between the two lies in that the shape of the female cavity C of the two is different. Please refer to FIG. 1H , FIG. 2 , FIG. 3 and FIG. 4 , specifically, the mother cavity C includes a plurality of sub-cavities c and sacrificial patterns 142 . In the embodiment of FIG. 1H and FIG. 2 , in the top view of the transducer 10 , the female cavity C is substantially rectangular. In the embodiment shown in FIG. 3 and FIG. 4 , in the top view of the transducer 10 , the female cavity C is substantially diamond-shaped.

Fig. 5 is a schematic top view and perspective view of a transducer according to another embodiment of the present invention. Fig. 6 is a schematic cross-sectional view of a transducer according to another embodiment of the present invention. Fig. 7 is a schematic cross-sectional view of a transducer according to another embodiment of the present invention. Figures 6 and 7 correspond to the line III-III' and the line IV-IV' in Figure 5, respectively. FIG. 5 shows the substrate 110 , the sacrificial pattern 142 , the vibrating film 150 and the second conductive layer 160 of the transducer 10B, while omitting other components of the transducer 10B.

The transducer 10B in FIG. 5 , FIG. 6 and FIG. 7 is similar to the transducer 10 in FIG. 1H and FIG. 2 , the difference between them is that the number of sub-cavities c included in the parent cavity C of the two is different.

Please refer to FIG. 5, FIG. 6 and FIG. 7. Specifically, in this embodiment, the different sides of the sacrificial pattern 142 include mutually different first sides (for example: the lower left side of the sacrificial pattern 142 in FIG. 5) , the second side (for example: the upper right side of the sacrifice pattern 142 of FIG. 5 ), the third side (for example: the upper left side of the sacrifice pattern 142 of FIG. 5 ) and the fourth side (for example: the lower right side of the sacrifice pattern 142 of FIG. side), the first side is opposite to the second side, the third side is opposite to the fourth side, and a plurality of sub-cavities c of a mother cavity C include the first side, the second side, and the third side of the sacrificial pattern 142 respectively. And the first sub-cavity c1, the second sub-cavity c2, the third sub-cavity c3 and the fourth sub-cavity c4 on the fourth side. That is to say, in this embodiment, the number of sub-cavities c of one parent cavity C may exceed 2, for example but not limited to: 4.

10, 10A, 10B: Transducer 110: Substrate 120: the first conductive layer 122: Lower electrode 130: insulating layer 140': sacrificial material layer 142': sacrifice block 142'-1: multiple places 142'-2: Internal 142: sacrifice pattern 142a: top surface 142b: bottom surface 142c: side 150': oscillating material membrane 150: Oscillating membrane 152: through hole 160: second conductive layer 162: Upper electrode 170: encapsulation layer 172: Sealed Department C: Mother cavity c: sub-cavity c1: first subcavity c2: second sub-cavity c3: third sub-cavity c4: fourth sub-cavity E: working element EL: etchant L: virtual straight line W: width x: direction I-I', II-II', III-III', IV-IV': broken line

1A to 1H are schematic cross-sectional views of the manufacturing process of a transducer according to an embodiment of the present invention. FIG. 2 is a schematic top view and perspective view of a transducer according to an embodiment of the present invention. FIG. 3 is a schematic top view and perspective view of a transducer according to another embodiment of the present invention. Fig. 4 is a schematic cross-sectional view of a transducer according to another embodiment of the present invention. Fig. 5 is a schematic top view and perspective view of a transducer according to another embodiment of the present invention. Fig. 6 is a schematic cross-sectional view of a transducer according to another embodiment of the present invention. Fig. 7 is a schematic cross-sectional view of a transducer according to another embodiment of the present invention.

10: Transducer

110: Substrate

120: the first conductive layer

122: Lower electrode

130: insulating layer

142: sacrifice pattern

142a: top surface

142b: bottom surface

142c: side

150: Oscillating membrane

152: through hole

160: second conductive layer

162: Upper electrode

170: encapsulation layer

172: Sealed Department

C: Mother cavity

c: sub-cavity

E: working element

I-I': section line

Claims (10)

A transducer comprising: a substrate; One electrode is set on the substrate; an insulating layer disposed on the lower electrode; a sacrificial pattern disposed on the insulating layer; an oscillating film, disposed on the sacrificial pattern, and has a plurality of through holes, wherein in the top view of the transducer, the through holes of the oscillating film are respectively located on different sides of the sacrificial pattern; a plurality of upper electrodes disposed on the vibrating membrane; and An encapsulation layer, including a plurality of sealing parts, wherein the sealing parts are respectively arranged in the through holes of the oscillating film and extend to the insulating layer; The oscillating film, the sealing parts of the encapsulation layer, the sacrificial pattern and the insulating layer define a plurality of sub-cavities, and the sacrificial pattern separates the sub-cavities. The transducer as claimed in claim 1, wherein in the plan view of the transducer, the upper electrodes are respectively located on the different sides of the sacrificial pattern. The transducer as claimed in claim 1, wherein in a plan view of the transducer, a virtual straight line passes through the through holes of the vibrating membrane, a direction is substantially parallel to the virtual straight line, and the sacrificial pattern is in A width in the direction increases away from the virtual straight line. The transducer according to claim 1, wherein the sacrificial pattern has an opposite top surface and a bottom surface, and the top surface and the bottom surface of the sacrificial pattern directly contact the vibrating film and the insulating layer respectively. The transducer as claimed in claim 1, wherein the sacrificial pattern has a side surface connecting the vibrating film and the insulating layer, and the side surface includes a curved surface. The transducer as claimed in claim 1, wherein a mother cavity includes the sub-cavities and the sacrificial pattern; in the top view of the transducer, the mother cavity is substantially a rhombus. The transducer as claimed in claim 1, wherein the different sides of the sacrificial pattern include a first side, a second side, a third side, and a fourth side that are different from each other, and the first side Opposite to the second side, the third side is opposite to the fourth side; the sub cavities include respectively located on the first side, the second side, the third side and the fourth side of the sacrificial pattern A first sub-cavity, a second sub-cavity, a third sub-cavity and a fourth sub-cavity. A method of manufacturing a transducer, comprising: forming a first conductive layer on a substrate, wherein the first conductive layer includes a lower electrode; forming an insulating layer on the first conductive layer; forming a sacrificial material layer on the insulating layer, wherein the sacrificial material layer includes a sacrificial area disposed on the upper electrode; forming an oscillating material film to cover the sacrificial material layer; forming a second conductive layer on the oscillating material film, wherein the second conductive layer includes a plurality of upper electrodes; forming a plurality of through holes in the oscillating material film, so that the oscillating material film forms an oscillating film, wherein the through holes respectively expose multiple places of the sacrificial block; Make an etchant enter the through-holes to remove the places of the sacrificial block corresponding to the through-holes, and leave an interior of the sacrificial block, wherein the remaining interior of the sacrificial block is called a sacrificial patterns; and An encapsulation layer is formed on the oscillating film, wherein the encapsulation layer includes a plurality of sealing portions, the sealing portions are respectively arranged in the through holes of the oscillating film and extend to the insulating layer, the oscillating film, the The sealing parts of the encapsulation layer, the sacrificial pattern and the insulating layer define a plurality of sub-cavities, and the sacrificial pattern separates the sub-cavities. The method for manufacturing a transducer as claimed in item 8, wherein a virtual straight line passes through the through holes of the vibrating membrane, a direction is substantially parallel to the virtual straight line, and a width of the sacrificial pattern in the direction varies with increases as it moves away from the virtual straight line. The method for manufacturing a transducer as claimed in claim 8, wherein the sacrificial pattern has a side surface connecting the vibrating film and the insulating layer, and the side surface includes a curved surface.