阅读说明：本技术 用于体声波谐振器制作的方法 (Method for manufacturing bulk acoustic wave resonator ) 是由 不公告发明人 于 2021-09-23 设计创作，主要内容包括：本申请涉体声波谐振器技术领域,公开一种用于体声波谐振器制作的方法,包括：提供待移除层,在待移除层从下往上依次形成谐振结构和牺牲层；在牺牲层上形成带有向下的第一凸起和向下的第二凸起的截止边界层,第一凸起和第二凸起均穿过牺牲层连接谐振结构；在截止边界层远离牺牲层的一侧形成谐振载体；移除待移除层；对谐振结构远离牺牲层的一侧进行刻蚀,并在刻蚀后的谐振结构上形成第一导通层和第二导通层；腐蚀第一凸起、第二凸起及谐振结构之间的牺牲层形成第一空腔。这样,能够对体声波谐振器进行双面制作,使得制作工艺更加灵活,且不需要在形成有空腔的衬底上制作谐振结构,从而便于体声波谐振器的制作。(The application relates to the technical field of bulk acoustic wave resonators, and discloses a method for manufacturing a bulk acoustic wave resonator, which comprises the following steps: providing a layer to be removed, and sequentially forming a resonance structure and a sacrificial layer from bottom to top on the layer to be removed; forming a cut-off boundary layer with a downward first bulge and a downward second bulge on the sacrificial layer, wherein the first bulge and the second bulge both penetrate through the sacrificial layer to be connected with the resonance structure; forming a resonance carrier on one side of the cut-off boundary layer far away from the sacrificial layer; removing the layer to be removed; etching one side of the resonant structure, which is far away from the sacrificial layer, and forming a first conducting layer and a second conducting layer on the etched resonant structure; and etching the first bump, the second bump and the sacrificial layer among the resonant structures to form a first cavity. Therefore, the bulk acoustic wave resonator can be manufactured on two sides, the manufacturing process is more flexible, a resonance structure does not need to be manufactured on the substrate with the cavity, and the bulk acoustic wave resonator is convenient to manufacture.)

1. A method for bulk acoustic wave resonator fabrication, comprising:

providing a layer to be removed, and sequentially forming a resonance structure and a sacrificial layer from bottom to top on the layer to be removed;

forming a cut-off boundary layer with a first downward bulge and a second downward bulge on the sacrificial layer, wherein the first bulge and the second bulge are connected with the resonant structure through the sacrificial layer;

forming a resonant carrier on one side of the cut-off boundary layer far away from the sacrificial layer;

removing the layer to be removed;

etching one side of the resonance structure far away from the sacrificial layer, and forming a first conducting layer and a second conducting layer on the etched resonance structure;

and corroding the first bump, the second bump and the sacrificial layer among the resonant structures to form a first cavity.

2. The method of claim 1, wherein the layer to be removed comprises a first substrate and a silicon oxide layer formed on the first substrate, and wherein forming a resonant structure on the layer to be removed comprises:

depositing an aluminum nitride layer, an upper electrode layer, a piezoelectric layer and a lower electrode layer on the silicon oxide layer from bottom to top in sequence;

depositing a lower electrode edge salient point layer on one side of the lower electrode layer, which is far away from the piezoelectric layer, and etching the lower electrode edge salient point layer to expose the lower electrode layer;

depositing a passivation layer on the lower electrode edge bump layer and the exposed lower electrode layer;

and etching the passivation layer, the lower electrode edge bump layer and the lower electrode layer to expose the piezoelectric layer.

3. The method of claim 1, wherein forming a cutoff boundary layer with a first downward projection and a second downward projection on the sacrificial layer comprises:

etching the sacrificial layer to form a first through hole and a second through hole; the first through hole and the second through hole are exposed out of the resonance structure;

and depositing a cut-off boundary layer on the sacrificial layer with the first through hole and the second through hole to form the cut-off boundary layer with the downward first bulge and the downward second bulge.

4. The method of claim 1, wherein forming a resonant carrier on a side of the cutoff boundary layer away from the sacrificial layer comprises:

depositing a first bonding layer on one side of the cut-off boundary layer far away from the sacrificial layer;

and bonding a second substrate on the side of the first bonding layer far away from the cut-off boundary layer to form a resonant carrier consisting of the first bonding layer and the second substrate.

5. The method of claim 2, wherein etching the side of the resonant structure remote from the sacrificial layer comprises:

etching the aluminum nitride layer and the upper electrode layer to expose the piezoelectric layer;

etching the aluminum nitride layer to form a third through hole, wherein the upper electrode layer is exposed out of the third through hole;

and etching the piezoelectric layer which is not in contact with the upper electrode layer and the aluminum nitride layer to form a fourth through hole, wherein the fourth through hole exposes the lower electrode layer.

6. The method of claim 5, wherein forming a first conductive layer and a second conductive layer on the etched resonant structure comprises:

forming a first conducting layer on the third through hole and the aluminum nitride layer on the periphery of the third through hole; the first conduction layer penetrates through the third through hole to be connected with the upper electrode layer;

forming a second conducting layer on the piezoelectric layer at the periphery of the fourth through hole and the fourth through hole; the second conducting layer penetrates through the fourth through hole to be connected with the lower electrode layer.

7. The method of claim 2, wherein the upper electrode layer and the lower electrode layer are each made of one or more of conductive molybdenum Mo, aluminum Al, copper Cu, platinum Pt, tantalum Ta, tungsten W, palladium Pd, and ruthenium Ru metallic materials.

8. The method of claim 4, wherein the first bonding layer is made of silicon dioxide, silicon nitride, or an organic film material.

9. The method of claim 4, wherein the second substrate is made of one or more of silicon oxide, aluminum oxide, carbon silicon, polysilicon, amorphous silicon, and single crystal silicon material.

10. Method according to any of claims 1 to 9, characterized in that the cut-off boundary layer is made of silicon nitride, aluminum nitride, polysilicon or amorphous silicon.

Technical Field

The present application relates to the field of bulk acoustic wave resonator technology, and for example, to a method for manufacturing a bulk acoustic wave resonator.

Background

At present, a conventional film bulk acoustic resonator structure includes an upper electrode, a piezoelectric layer, and a lower electrode, and a cavity of the resonator is usually etched on a substrate, and then the lower electrode, the piezoelectric layer, the upper electrode, and the like are fabricated on the cavity, so as to form a complete resonator.

In the process of implementing the embodiment of the invention, the following problems are found in the related art at least:

the existing resonator is limited by the substrate cavity, and the resonator is inconvenient to manufacture.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview nor is intended to identify key/critical elements or to delineate the scope of such embodiments but rather as a prelude to the more detailed description that is presented later.

The embodiment of the invention provides a method for manufacturing a bulk acoustic wave resonator, which is convenient for manufacturing the bulk acoustic wave resonator.

In some embodiments, a method for bulk acoustic wave resonator fabrication, comprises: providing a layer to be removed, and sequentially forming a resonance structure and a sacrificial layer from bottom to top on the layer to be removed; forming a cut-off boundary layer with a first downward bulge and a second downward bulge on the sacrificial layer, wherein the first bulge and the second bulge are connected with the resonant structure through the sacrificial layer; forming a resonant carrier on one side of the cut-off boundary layer far away from the sacrificial layer; removing the layer to be removed; etching one side of the resonance structure far away from the sacrificial layer, and forming a first conducting layer and a second conducting layer on the etched resonance structure; and corroding the first bump, the second bump and the sacrificial layer among the resonant structures to form a first cavity.

The method for manufacturing the bulk acoustic wave resonator provided by the embodiment of the invention can realize the following technical effects: a sacrificial layer, a cut-off boundary layer and a resonant carrier are firstly manufactured on one side of a resonant structure, a conducting layer is manufactured on the other side of the resonant structure, and then a first cavity is formed by corroding the sacrificial layer after the conducting layer is manufactured. Therefore, the bulk acoustic wave resonator can be manufactured on two sides, the manufacturing process is more flexible, a resonance structure does not need to be manufactured on the substrate with the cavity, and the bulk acoustic wave resonator is convenient to manufacture.

The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the accompanying drawings and not in limitation thereof, in which elements having the same reference numeral designations are shown as like elements and not in limitation thereof, and wherein:

FIG. 1 is a schematic diagram of a method for fabricating a bulk acoustic wave resonator according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a layer to be removed according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of an aluminum nitride layer, an upper electrode layer, a piezoelectric layer, and a lower electrode layer deposited on a layer to be removed in sequence from bottom to top according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a bump layer on the edge of a lower electrode layer after deposition and etching of the lower electrode layer according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a bump layer deposited on the edge of a lower electrode according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a passivation layer, a lower electrode edge bump layer, and a lower electrode layer after etching according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of the resonator structure after a sacrificial layer is deposited and etched according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a structure after a sacrificial layer is deposited to cut off a boundary layer according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a structure after a first bonding layer is deposited by a cut-off boundary layer according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of a bonded second substrate on a first bonding layer according to an embodiment of the present invention;

FIG. 11 is a schematic diagram illustrating a structure after a layer to be removed is removed according to an embodiment of the present invention;

FIG. 12 is a schematic structural diagram illustrating an aluminum nitride layer and an upper electrode layer after etching according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of an aluminum nitride layer and a piezoelectric layer after etching according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram after a conductive layer is formed according to an embodiment of the present invention;

FIG. 15 is a schematic diagram of a structure after etching a first cavity according to an embodiment of the present invention;

fig. 16 is a schematic diagram of a frequency response curve of a filter according to an embodiment of the present invention.

Reference numerals:

100: a first substrate; 110: a silicon oxide layer; 120: an aluminum nitride layer; 130: an upper electrode layer; 140: a piezoelectric layer; 150: a lower electrode layer; 160: a lower electrode edge bump layer; 170: a passivation layer; 180: a sacrificial layer; 190: stopping the boundary layer; 200: a first bonding layer; 210: a second substrate; 220: a second conductive layer; 230: a first conductive layer.

Detailed Description

So that the manner in which the features and aspects of the embodiments of the present invention can be understood in detail, a more particular description of the embodiments of the invention, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the appended drawings. In the following description of the technology, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may be practiced without these details. In other instances, well-known structures and devices may be shown in simplified form in order to simplify the drawing.

The terms "first," "second," and the like in the description and in the claims, and in the drawings, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the invention described herein may be used. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover non-exclusive inclusions.

The term "plurality" means two or more unless otherwise specified.

In the embodiment of the present invention, the character "/" indicates that the preceding and following objects are in an or relationship. For example, A/B represents: a or B.

The term "and/or" is an associative relationship that describes objects, meaning that three relationships may exist. For example, a and/or B, represents: a or B, or A and B.

Referring to fig. 1, an embodiment of the present invention provides a method for manufacturing a bulk acoustic wave resonator, including:

step S101, providing a layer to be removed, and sequentially forming a resonance structure and a sacrificial layer on the layer to be removed from bottom to top;

step S102, forming a cut-off boundary layer with a downward first bulge and a downward second bulge on the sacrificial layer, wherein the first bulge and the second bulge both penetrate through the sacrificial layer to connect the resonance structure;

step S103, forming a resonance carrier on one side of the cut-off boundary layer far away from the sacrificial layer;

step S104, removing the layer to be removed;

step S105, etching one side of the resonant structure, which is far away from the sacrificial layer, and forming a first conducting layer and a second conducting layer on the etched resonant structure;

step S106, a first cavity is formed by etching the first protrusion, the second protrusion and the sacrificial layer among the resonant structures.

According to the method for manufacturing the bulk acoustic wave resonator, the sacrificial layer, the cut-off boundary layer and the resonant carrier are manufactured on one side of the resonant structure, the conducting layer is manufactured on the other side of the resonant structure, and then the sacrificial layer is corroded to form the first cavity after the conducting layer is manufactured. Therefore, the bulk acoustic wave resonator can be manufactured on two sides, the manufacturing process is more flexible, a resonance structure does not need to be manufactured on the substrate with the cavity, and the bulk acoustic wave resonator is convenient to manufacture.

As shown in fig. 2 to 6, optionally, the layer to be removed includes a first substrate 100 and a silicon oxide layer 110 formed on the first substrate, and the resonant structure is formed on the layer to be removed, including: depositing an aluminum nitride layer 120, an upper electrode layer 130, a piezoelectric layer 140 and a lower electrode layer 150 on the silicon oxide layer 110 from bottom to top in sequence; depositing a lower electrode edge bump layer 160 on a side of the lower electrode layer 150 away from the piezoelectric layer 140, and etching the lower electrode edge bump layer 160 to expose the lower electrode layer 150; depositing a passivation layer 170 on the lower electrode edge bump layer 160 and the exposed lower electrode layer 150; the passivation layer 170, the lower electrode edge bump layer 160, and the lower electrode layer 150 are etched to expose the piezoelectric layer 140.

Optionally, the first substrate is made of silicon, carbon silicon, alumina, quartz or glass.

In some embodiments, the silicon oxide layer is deposited on the first substrate by a CVD (Chemical Vapor Deposition) process. In some embodiments, in the case where the first substrate is made of silicon, a silicon oxide layer is formed on the first substrate by oxidizing the first substrate.

Alternatively, the upper electrode layer is made of one or more of metal materials having conductive properties such as molybdenum Mo, aluminum Al, copper Cu, platinum Pt, tantalum Ta, tungsten W, palladium Pd, and ruthenium Ru.

Alternatively, the lower electrode layer is made of one or more of metal materials having conductive properties such as molybdenum Mo, aluminum Al, copper Cu, platinum Pt, tantalum Ta, tungsten W, palladium Pd, and ruthenium Ru.

Optionally, the piezoelectric layer is made of AlN nitride, ZnO, LiNbO₃Lithium tantalate LiTaO₃Lead zirconate titanate (PZT), Barium Strontium Titanate (BST), and the like.

Optionally, the piezoelectric layer is made of aluminum nitride AlN doped with a rare earth element in a proportion of 5-30%. Optionally, the rare earth elements include: scandium, erbium, lanthanum and the like.

In some embodiments, the lower electrode edge bump layer is etched by a Lift-off process (metal Lift-off technology) to expose the lower electrode layer.

In some embodiments, the lower electrode edge bump layer is patterned and etched to expose the lower electrode layer.

Optionally, the lower electrode edge bump layer is made of one or more of metal materials with conductive properties such as molybdenum Mo, aluminum Al, copper Cu, platinum Pt, tantalum Ta, tungsten W, palladium Pd, and ruthenium Ru.

In some embodiments, the metal material of the lower electrode layer is deposited on the piezoelectric layer to a thickness equal to the total thickness of the lower electrode layer and the lower electrode edge bump layer, in the case that the metal material of the lower electrode layer and the lower electrode edge bump layer are the same. For example: the lower electrode layer and the lower electrode edge salient point layer are made of molybdenum, the thickness of the lower electrode layer is 2 micrometers, the thickness of the lower electrode edge salient point layer is 1 micrometer, 3 micrometers of molybdenum is deposited on the piezoelectric layer, and the lower electrode layer and the lower electrode edge salient point layer exposing the lower electrode layer are formed by graphically etching molybdenum metal with the etching thickness of 1 micrometer.

Optionally, the passivation layer is made of silicon nitride SiN, aluminum nitride AlN, or silicon dioxide SiO₂And silicon oxynitride SiNO.

In some embodiments, the passivation layer, the lower electrode edge bump layer and the lower electrode layer are etched by a plasma etching process or a wet chemical etching process to expose the piezoelectric layer, forming a lower electrode pattern. Like this, before the preparation cavity, carry out the sculpture to passivation layer, bottom electrode marginal bump layer, bottom electrode layer, can realize the accurate imaging to FBAR (film bulk acoustic resonator filter) syntonizer bottom electrode, can realize the two-sided placing of bump through this process flow simultaneously, promote the effect of syntonizer.

As shown in fig. 7 and 8, a cut-off boundary layer 190 with a downward first protrusion and a downward second protrusion is optionally formed on the sacrificial layer 180, and includes: etching is performed on the sacrificial layer 180 to form a first through hole and a second through hole; the first through hole and the second through hole are exposed out of the resonance structure; a cut-off boundary layer 190 is deposited on the sacrificial layer 180 with the first through hole and the second through hole, forming a cut-off boundary layer 190 with a first protrusion and a second protrusion downward.

Optionally, the material of the sacrificial layer is silicon dioxide.

Optionally, the cutoff boundary layer is made of one or more of silicon nitride, aluminum nitride, polysilicon, and amorphous silicon.

As shown in fig. 9 to 11, optionally, the forming of the resonant carrier on the side of the cut-off boundary layer 190 away from the sacrificial layer 180 includes: depositing a first bonding layer 200 on the side of the cut-off boundary layer 190 away from the sacrificial layer 180; and bonding a second substrate 210 on the side of the first bonding layer 200 far away from the cutoff boundary layer 190 to form a resonant carrier consisting of the first bonding layer 200 and the second substrate 210.

Optionally, the first bonding layer is made of silicon dioxide, silicon nitride or an organic film material.

In some embodiments, the organic film material includes: dry Film, Die Attach Film, and the like.

In some embodiments, the first bonding layer is surface planarized and polished by CMP (chemical mechanical polishing).

In some embodiments, the first substrate is removed by one or more of a grinding process, a plasma dry etch process, and a wet chemical etch process. The silicon oxide layer is removed by plasma dry etching and/or wet chemical etching.

As shown in fig. 12 and 13, optionally, etching the resonant structure on the side away from the sacrificial layer 180 includes: etching the aluminum nitride layer 120 and the upper electrode layer 130 to expose the piezoelectric layer 140; etching the aluminum nitride layer 120 to form a third through hole, wherein the upper electrode layer is exposed out of the third through hole; the piezoelectric layer 140, which is not in contact with the upper electrode layer 130 and the aluminum nitride layer 120, is etched to form a fourth through hole, which exposes the lower electrode layer 150.

In some embodiments, the aluminum nitride layer and the upper electrode layer are patterned by a plasma etch process and/or a wet chemical etch process to form an upper electrode of the FBAR resonator and expose the piezoelectric layer. Thus, the parasitic capacitance of the FBAR can be minimized by accurately patterning the upper electrode of the FBAR without forming a cavity and matching with the accurate patterning of the lower electrode.

In some embodiments, the aluminum nitride layer is patterned to form a third via hole, through which the upper electrode layer is exposed; the third through hole is a conduction contact window of the upper electrode of the FBAR resonator. And patterning and etching the piezoelectric layer which is not in contact with the upper electrode layer and the aluminum nitride layer to form a fourth through hole, exposing the lower electrode layer through the fourth through hole, and enabling the fourth through hole to be a lower electrode conduction through hole of the FBAR resonator.

As shown in fig. 14, optionally, forming a first conducting layer 230 and a second conducting layer 220 on the etched resonant structure includes: forming a first conductive layer 230 on the third via hole and the aluminum nitride layer 120 around the third via hole; the first conductive layer 230 is connected to the upper electrode layer 130 through the third via hole; forming a second conductive layer 220 on the piezoelectric layer 140 at the periphery of the fourth through hole and the fourth through hole; the second conductive layer 220 is connected to the lower electrode layer 150 through the fourth via hole.

In some embodiments, the first and second conductive layers each include circuit conducting leads and pads made of one or a combination of metals such as aluminum Al, copper Cu, gold Au, titanium Ti, tungsten W, platinum Pt, and the like.

Referring to fig. 15, in some embodiments, in the case that the sacrificial layer is made of silicon Oxide, the first cavity is formed by etching the sacrificial layer between the first protrusion, the second protrusion and the resonant structure through one or more of hydrofluoric acid solution wet etching, BOE (Buffered Oxide etch) solution wet etching and hydrofluoric acid vapor etching, as shown in fig. 15, which is a schematic structural diagram after etching the first cavity.

The resonance structure manufactured by the scheme does not need to form a first cavity in the silicon substrate like the traditional bulk acoustic wave resonator, so that the substrate can flexibly select completely insulating materials except silicon materials, the problem that a parasitic conductive channel is generated due to the existence of a substrate silicon interface is avoided, and the performance of a filter formed by a plurality of bulk acoustic wave resonators is improved. In some embodiments, fig. 16 is a schematic diagram of the frequency response curve of the filter, and as shown in fig. 16, curve a is the frequency response curve of the filter composed of the substrate resonators made of silicon, and the S parameter is S (3, 4). Curve B is using silica, Al₂O₃Frequency response curve of filter composed of resonators with substrate of completely insulating materialLine with S parameter S (2, 1). As shown in FIG. 16, silica or Al is used₂O₃Filters composed of fully insulated material-backed resonators, as represented, have a lower out-of-band response, i.e., better out-of-band filter rejection performance, than filters composed of silicon-backed resonators.

The above description and drawings sufficiently illustrate embodiments of the invention to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. The examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in or substituted for those of others. Furthermore, the words used in the specification are words of description only and are not intended to limit the claims. As used in the description of the embodiments and the claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Similarly, the term "and/or" as used in this application is meant to encompass any and all possible combinations of one or more of the associated listed. Furthermore, the terms "comprises" and/or "comprising," when used in this application, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Without further limitation, an element defined by the phrase "comprising an …" does not exclude the presence of other like elements in a process, method or apparatus that comprises the element. In this document, each embodiment may be described with emphasis on differences from other embodiments, and the same and similar parts between the respective embodiments may be referred to each other. For methods, products, etc. of the embodiment disclosures, reference may be made to the description of the method section for relevance if it corresponds to the method section of the embodiment disclosure.