WO2023274343A1

WO2023274343A1 - Filter and fabrication method therefor

Info

Publication number: WO2023274343A1
Application number: PCT/CN2022/102622
Authority: WO
Inventors: 唐兆云; 杨清华; 赖志国
Original assignee: 苏州汉天下电子有限公司
Priority date: 2021-07-01
Filing date: 2022-06-30
Publication date: 2023-01-05
Also published as: CN113411067A; CN113411067B

Abstract

The content of the present disclosure relates to a filter, comprising: a substrate; one or more resonators which are disposed on the substrate; and a dam structure which is disposed on the substrate and surrounds the one or more resonators, wherein the dam structure extends to the interior of the substrate. In addition, the content of the present disclosure also relates to a method for fabricating a filter, comprising: providing a substrate, and forming one or more resonators on the substrate; and forming a dam structure on the substrate, wherein the dam structure surrounds the one or more resonators and extends to the interior of the substrate.

Description

Filter and its manufacturing method

technical field

The present disclosure relates to the technical field of semiconductors, and in particular, the present disclosure relates to filters and manufacturing methods thereof.

Background technique

A film bulk acoustic resonator (Film Bulk Acoustic Resonator, FBAR) is manufactured using a silicon substrate using micro-electro-mechanical system (Micro-Electro-Mechanical System, MEMS) technology and thin-film technology. Thin film cavity resonator filters are usually provided with a single seal ring. The single seal is deposited directly on the substrate. The bottom layer of the single sealing ring will undergo hydrolysis reaction under certain conditions. When the film cavity acoustic resonance filter device works under severe working conditions, moisture can easily invade the device through the bottom layer, causing the device to fail.

Therefore, thin-film cavity acoustic resonator filters usually use multi-layer sealing rings. This means that, in addition to the sealing ring deposited directly on the substrate, additional sealing rings are formed by means of electroplating during the packaging phase. However, this undoubtedly increases the manufacturing complexity and further increases the cost.

Contents of the invention

A brief summary of the present disclosure is presented below in order to provide a basic understanding of certain aspects of the present disclosure. It should be understood, however, that this summary is not an exhaustive overview of the disclosure, nor is it intended to identify key or critical parts of the disclosure, nor to limit the scope of the disclosure. The sole purpose of this summary is to present some inventive concepts related to the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

An object of the present disclosure is to provide a filter and a manufacturing method thereof capable of overcoming the above-mentioned problems existing in the prior art.

According to one aspect of the present disclosure, there is provided a filter comprising: a substrate; one or more resonators disposed on the substrate; and a dam structure disposed on the substrate and surrounding one or more a resonator, wherein the dam structure extends into the interior of the substrate.

According to another aspect of the present disclosure, there is provided a method of manufacturing a filter, which includes: providing a substrate, forming one or more resonators on the substrate; forming a dam structure on the substrate, the dam structure Surrounds the one or more resonators and extends into the interior of the substrate.

According to a further aspect of the present disclosure, there is provided an electronic device comprising one or more filters according to the above aspects of the present disclosure.

The filter according to the present disclosure can achieve good sealing effect without multi-layer sealing rings. By improving the structure of the filter, the intrusion of moisture under extreme working conditions can be effectively prevented without increasing the manufacturing complexity, thereby significantly improving the moisture resistance of the filter. In addition, according to the filter manufacturing method of the present disclosure, due to the simplification of the process, the manufacturing cost can be significantly reduced.

Description of drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. In the attached picture:

Figure 1A shows a cross-sectional view of a filter according to an embodiment of the disclosure;

Figure 1B shows a partially enlarged cross-sectional view of a filter according to an embodiment of the present disclosure;

Figure 1C shows a top view of an arrangement of acoustic resonators of a filter according to an embodiment of the disclosure;

2A to 2O show cross-sectional views in a process for manufacturing a filter according to an embodiment of the present disclosure.

detailed description

In this specification, it will be understood that when a component (or region, layer, section) is referred to as being "on", "connected to" or "coupled to" another component (or region, layer, section) When there are components (or regions, layers, parts), the one component may be directly disposed on the other component, directly connected to or directly coupled to the other component, or there may be an intervening component therebetween. In contrast, in this specification, when an element (or region, layer, section) is referred to as being "directly on" another element (or region, layer, section), "directly connected to" or "directly coupled to To" another component (or region, layer, section) without intervening components placed between them.

The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. However, this disclosure may be implemented in many different ways and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like parts throughout. Also, in the drawings, the thicknesses, ratios, and sizes of components may be exaggerated for clarity of illustration.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," "the," and "at least one" do not imply a limitation of quantity, but are intended to include both the singular and the plural unless the context clearly dictates otherwise. For example, "an element" has the same meaning as "at least one element" unless the context clearly dictates otherwise. "At least one" should not be construed as limited to "a" or "one". "Or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood that although terms such as "first" and "second" are used herein to describe various components, these components should not be limited by these terms. These terms are only used to distinguish one component from other components. For example, an element termed a first element in one embodiment could be termed a second element in other embodiments without departing from the scope of the appended claims.

In addition, "below", "below", "above", "upper" and the like are used to describe the relative relationship of components shown in the drawings. These terms may be relative concepts and are described based on the directions presented in the drawings.

"About" or "approximately" as used herein encompasses the stated value and the term "approximately" as used by a person of ordinary skill in the art, taking into account the measurement of the particular quantity in question and the errors associated with that measurement (i.e., limitations of the measurement system). The average value determined to be within the acceptable range of deviation for this value. For example, "about" can mean a mean within one or more standard deviations, or a mean within ±30%, 20%, 10%, 5% of the stated value.

Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art. Terms as defined in commonly used dictionaries should be construed as having the same meanings as in the relevant technical context, and unless expressly defined in the specification, these terms should not be interpreted in an idealized or overly formal sense Terminology explained.

"Comprising" or "comprising" indicates the presence of properties, quantities, steps, operations, elements, parts or combinations thereof, but does not exclude the presence of other properties, numbers, steps, operations, elements, parts or combinations thereof or add.

Embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. Accordingly, variations in shape from the illustrations as a result, for example, of manufacturing techniques and/or tolerances are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Also, acute corners shown may be rounded. Thus, the regions shown in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.

Hereinafter, exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.

FIG. 1A shows a cross-sectional view of a filter 10 according to an embodiment of the present disclosure, FIG. 1B shows a partially enlarged cross-sectional view of a filter 10 according to an embodiment of the present disclosure, and FIG. Top view of the arrangement of the acoustic resonators of the filter 10 of the disclosed embodiment.

Referring to FIGS. 1A to 1C , a filter 10 according to an embodiment of the present disclosure may include a substrate 1 , an acoustic reflection structure 2 , a dam structure 3 and a piezoelectric material layer 4 . Here, only one acoustic reflection structure is shown by way of example. As shown in FIG. 1A, a substrate 1 includes a concave portion provided thereon. In this example, the sound-reflecting structure is represented by way of example by a cavity designed as a depression. Alternatively, the sound-reflecting structure can also be a Bragg reflector. Here, although the embodiment of the Bragg reflector as the acoustic reflection structure is not shown, those skilled in the art can understand that in this case, the Bragg reflector can be arranged on the substrate 1 instead of the recess.

According to an embodiment of the present disclosure, the piezoelectric material layer 4 may be disposed on the substrate 1 and cover the acoustic reflection structure 2 such that an acoustic resonator is formed corresponding to the acoustic reflection structure 2 . According to an embodiment of the present disclosure, the dam structure 3 may extend above the substrate 1 through the piezoelectric material layer 4 into the interior of the substrate 1 to surround all the acoustic resonators. According to an embodiment of the present disclosure, the lower end of the dam structure 3 may extend to the inside of the substrate 1 .

Fig. 1B shows an enlarged view of a part of the embankment structure 3 of the filter 10 marked with dashed box AA' in Fig. 1A. According to an embodiment of the present disclosure, the embankment structure 3 may include a first portion 31 and a second portion 32 arranged in a horizontal direction. According to an embodiment of the present disclosure, one side of the first portion 31 is adjacent to the second portion 32 in the horizontal direction, and the opposite side of the first portion 31 is adjacent to the piezoelectric material layer 4 in the horizontal direction. According to an embodiment of the present disclosure, the lower end of the second portion 32 of the embankment structure 3 may extend into the interior of the substrate 1 . In other words, according to the embodiment of the present disclosure, the bottom surface of the second part 32 and the bottom surface of the first part 31 are not in the same plane, but there is a height difference between the bottom surface of the second part 32 and the bottom surface of the first part 31 . According to an embodiment of the present disclosure, the lower end of the second portion 32 of the embankment structure 3 extends to the inside of the substrate 1 . According to an embodiment of the present disclosure, the depth H at which the lower end of the second portion 32 extends into the interior of the substrate 1 is in the range of 0 to 20 μm. According to an embodiment of the present disclosure, the depth H is preferably 2 μm, 4 μm, 6 μm, 8 μm or 12 μm.

As shown in FIG. 1A , a filter 10 according to an embodiment of the present disclosure may further include a bottom electrode 5 and a top electrode 6 , which form a sandwich structure of an acoustic resonator with a piezoelectric material layer 4 sandwiched therebetween. Figure 1A only exemplarily shows the arrangement of the bottom electrode 5 and the top electrode 6, and it should be understood by those skilled in the art that the arrangement of the bottom electrode 5 and the top electrode 6 is not limited to what is shown in the figure, but can be Adjust as needed. In addition, according to an embodiment of the present disclosure, the bottom electrode 5 and the top electrode 6 may generally have a stripe shape, ie, a rectangular shape as shown in FIG. 1C . It should be understood by those skilled in the art that the bottom electrode 5 and the top electrode 6 can have any shape that meets the requirements of the manufacturing process.

According to an embodiment of the present disclosure, the bottom electrode 5 and the top electrode 6 may be formed of the same electrically conductive material. Alternatively, according to an embodiment of the present disclosure, the bottom electrode 5 and the top electrode 6 may also be formed of different materials. According to an embodiment of the present disclosure, the electrically conductive material may be a metal. According to the embodiment of the present disclosure, any material that can conduct electricity and meet the manufacturing process requirements of the filter of the present disclosure can be used as the material for forming the bottom electrode 5 and the top electrode 6 .

An arrangement of multiple acoustic resonators of a filter 10 according to an embodiment of the disclosure is exemplarily shown in FIG. 1C . For the sake of clarity, the filter 10 shown in FIG. 1C has the top electrode 6, the covering part 7 and part of the piezoelectric material layer 4 removed. Fig. 1C only exemplarily shows four acoustic resonators. However, the filter 10 according to the embodiment of the present disclosure is not limited to including four acoustic resonators, but more or fewer acoustic resonators may be provided according to specific application requirements. According to an embodiment of the present disclosure, as shown in FIG. 1C , the embankment structure 3 surrounds all the acoustic resonators. It should be pointed out that although the bottom electrode 5 has a rectangular shape in FIG. 1C, those skilled in the art will recognize that by adjusting the mask used in the manufacturing process of the filter described below in conjunction with FIGS. 2A to 2O, it is possible to form Bottom electrodes 5 of other desired shapes.

As shown in FIG. 1A , the filter 10 according to the embodiment of the present disclosure may further include a covering part 7 . The cover 7 may be bonded to the top of the embankment structure 3, thereby enclosing the sandwich structure of the acoustic resonator therein. Those skilled in the art should realize that the specific shape and structure of the covering portion 7 are not limited to the shape and structure shown in FIG. 1A , but can be changed according to actual application requirements.

Unlike the prior art, according to embodiments of the present disclosure, the dam structure 3 extending into the substrate 1 is formed around the piezoelectric material layer 4 directly during the manufacture of the filter 10 by means of etching and deposition processes. Under the condition of not increasing the manufacturing cost, the embankment structure 3 forms a more effective sealing structure. The second portion 32 of the embankment structure 3 extending into the interior of the substrate 1 blocks moisture intrusion and significantly improves the moisture resistance of the filter 10 .

According to an embodiment of the present disclosure, the depth H by which the lower ends of the first portion 31 and the second portion 32 of the embankment structure 3 extend into the interior of the substrate 1 can be set according to a specific manufacturing process. The uneven tops of the first part 31 and the second part 32 of the embankment structure 3 are only schematically shown in FIG. 1B . However, according to alternative embodiments of the present disclosure, the tops of the first portion 31 and the second portion 32 may be flush, unlike that shown in FIGS. 1A and 1B .

According to an embodiment of the present disclosure, when the filter 10 operates, a high-frequency voltage signal is applied to the bottom electrode 5 and the top electrode 6, thereby generating a bulk acoustic wave along the inner side of the piezoelectric material layer 4. At the same time, depending on the thickness of the piezoelectric material layer 4, resonance can be induced at a corresponding frequency.

For a thin-film cavity acoustic resonator filter, the piezoelectric material layer 4 may contain, for example, AlN, ZnO, or PzT. For the surface acoustic wave filter, the piezoelectric material layer may include, for example, LiTaO ₃ , LiNbO ₃ or SiO ₂ .

According to an embodiment of the present disclosure, the substrate 1 may comprise, for example, a silicon-based material. According to an embodiment of the present disclosure, the substrate 1 may contain, for example, sapphire or silicon carbide.

According to an embodiment of the present disclosure, the embankment structure 3 may comprise a material with low electrical conductivity, good heat transfer and good airtightness. According to an embodiment of the present disclosure, the embankment structure 3 may comprise, for example, ceramics, plastics, metals or metal matrix composites or the like.

2A to 2O show cross-sectional views in a process of manufacturing the filter 10 shown in FIG. 1A . In FIGS. 2A to 2O , the same components as those in FIGS. 1A to 1C are denoted by the same reference numerals. According to an embodiment of the present disclosure, the method for manufacturing the filter 10 may include: providing a substrate 1, forming one or more resonators on the substrate 1; and forming a bank structure 3 on the substrate 1, which Arranged around one or more resonators and extending into the interior of the substrate 1 .

According to an embodiment of the present disclosure, forming one or more resonators on the substrate 1 includes the following steps.

After the substrate 1 is provided, as shown in FIG. 2A , a concave portion serving as the acoustic reflection structure 2 is formed on the substrate 1 . Subsequently, a sacrificial layer is deposited inside the recess, and a seed layer 401 is deposited on the sacrificial layer. According to an embodiment of the present disclosure, the seed layer may be AlN. Subsequently, a bottom electrode layer 501 is deposited on the seed layer 401 . According to an embodiment of the present disclosure, the bottom electrode layer 501 may be any material that is conductive and meets the requirements of the deposition process.

As shown in FIG. 2B , a photoresist G1 is coated on the bottom electrode layer 501 . Subsequently, the bottom electrode layer 501 and the seed layer 401 are etched by photolithography through the mask M1. According to an embodiment of the present disclosure, the bottom electrode layer 501 and the seed layer 401 are photo-etched by dry etching. Thus, bottom electrode 5 is formed. According to an embodiment of the present disclosure, as shown in FIG. 2C , by adjusting the setting of the mask M1 , the bottom electrodes 5 at the ends can be partially etched to expose the seed layers at both ends. The shape of the bottom electrode 5 depends on the pattern of the mask M1 and the photoresist G1. Subsequently, as shown in FIG. 2D , the exposed seed layer 401 is removed by wet etching. Subsequently, the photoresist G1 may be removed after the bottom electrode 5 is formed.

Subsequently, as shown in FIG. 2E , a piezoelectric material layer 4 is deposited on the bottom electrode layer 5 and the surface of the substrate 1 exposed by etching, and a top electrode layer 601 is deposited on the piezoelectric material layer 4 . Optionally, a protective layer 602 may be deposited on the top electrode layer 601 . According to an embodiment of the present disclosure, during the process of depositing each layer, the heights at both ends of the protective layer 602, the top electrode layer 601, and the piezoelectric material layer 4 may be lower than the middle height by processes such as CMP. Figure 2E shows an exemplary embodiment in which a top electrode layer 601 and a protective layer 602 are deposited. According to an embodiment of the present disclosure, similar to the bottom electrode layer 501 , the top electrode layer 601 may also be any material that is conductive and meets the requirements of the deposition process. According to an embodiment of the present disclosure, the material of the top electrode layer 601 may be the same as that of the bottom electrode layer 501 . Alternatively, the material of the top electrode layer 601 may also be different from that of the bottom electrode layer 501 .

Subsequently, as shown in FIG. 2F , a photoresist G2 is coated on the protective layer 602 . Subsequently, by photolithography, the protection layer 602 and the top electrode layer 601 are etched to form the top electrode 6 and the passivation layer 11 . Subsequently, as shown in FIG. 2G, the photoresist G2 is removed. At this time, the heights of both ends of the piezoelectric material layer 4 are lower than the middle height thereof.

Subsequently, as shown in FIG. 2H , a photoresist G3 is coated on the exposed piezoelectric material layer 4 and the passivation layer 11 . Subsequently, the passivation layer 11 is etched by photolithography by means of the mask M2, so that the top electrode 6 is partially exposed. According to an embodiment of the present disclosure, by adjusting the setting of the mask M2, the piezoelectric material layer 4 at both ends can be etched while the passivation layer 11 is etched. Subsequently, as shown in FIG. 2I, the photoresist G3 is removed.

Subsequently, according to an embodiment of the present disclosure, the dam structure 3 may be formed on the substrate 1 through the following process steps.

As shown in FIG. 2J , a photoresist G4 is coated on the piezoelectric material layer 4 and the passivation layer 11 . According to an embodiment of the present disclosure, the coating shape of the photoresist G4 determines the shape of the subsequently formed bank structure 3 . The photoresist G4 can be coated according to specific application requirements. As shown in Figure 2K, after the photoresist G4 is coated, the piezoelectric material layer 4 is etched. When the bottom electrode 5 is etched, both ends of the piezoelectric material layer 4 have been etched into the substrate 1 . It can be seen in FIG. 2K that the bottom electrode 5 , the top electrode 6 and the piezoelectric material layer 4 sandwiched therein form a sandwich structure of a resonator.

According to an embodiment of the present disclosure, the depth H etched into the interior of the substrate 1 may be in the range of 0 to 20 μm. According to an embodiment of the present disclosure, the depth may be 2 μm, 4 μm, 6 μm, 8 μm or 12 μm.

Subsequently, as shown in FIG. 2L , a photoresist G5 is coated on the piezoelectric material layer 4 and the passivation layer 11 . Next, bonding layer deposition is performed on the exposed substrate 1 and bottom electrode 5 . As shown in FIG. 2M , the bonding layer extends to the inside of the substrate 1 at the end, thereby forming a bank structure 3 . Next, as shown in FIG. 2N, the photoresist G5 is removed.

Subsequently, as shown in FIG. 2O , after the embankment structure 3 is formed, the covering portion 7 is bonded on top of the embankment structure 3 . According to an embodiment of the present disclosure, the covering part 7 and the embankment structure 3 realize the sealing of the resonator. Those skilled in the art should recognize that the specific shape and structure of the covering portion 7 are not limited to those shown in the drawings, but can be changed according to actual requirements.

One or more filters according to the present disclosure thus fabricated may be used in electronic devices.

Although the present disclosure has been described with reference to exemplary embodiments of the present disclosure, those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure as set forth in the claims. .

Claims

A filter comprising:

Substrate;

one or more resonators disposed on the substrate; and

a dam structure disposed on the substrate and surrounding the one or more resonators,

Wherein, the dam structure extends into the interior of the substrate.
The filter according to claim 1, wherein the embankment structure includes a first portion and a second portion disposed in a horizontal direction.
The filter according to claim 2, wherein a lower end of at least one of the first portion and the second portion extends to an inside of the substrate.
The filter according to claim 3, wherein the depth at which the lower end extends into the interior of the substrate is in the range of 0 to 20 [mu]m.
The filter according to any one of claims 2 to 4, wherein the filter further comprises a covering part bonded to the top of the first part or the second part of the embankment structure.
A filter according to any one of claims 2 to 4, wherein the first part and/or the second part of the embankment structure comprises a bonding metal.
A filter according to any one of claims 2 to 4, wherein one side of the first portion is horizontally adjacent to the second portion, and the opposite side of the first portion is horizontally adjacent to The piezoelectric material layers of the one or more resonators are contiguous.
A method of manufacturing a filter, comprising the steps of:

provide the substrate;

forming one or more resonators on the substrate; and

A dam structure is formed on the substrate, wherein the dam structure surrounds the one or more resonators and extends into the interior of the substrate.
The method according to claim 8, further comprising: forming a cover on the dam structure, wherein the cover and the dam structure seal the resonator.
The method according to claim 8 or 9, wherein forming the dam structure on the substrate comprises: forming a first portion and a second portion of the dam structure on the substrate in a horizontal direction such that A lower end of at least one of the first portion and the second portion extends to an inside of the substrate.
The method of claim 10, wherein the lower end extends to an interior of the substrate to a depth in a range of 0 to 20 μm.
An electronic device comprising one or more filters according to any one of claims 1-7.