阅读说明：本技术 谐振器和滤波器 (Resonator and filter ) 是由 李亮 吕鑫 梁东升 刘青林 马杰 高渊 丁现朋 冯利东 商庆杰 钱丽勋 李丽 于 2019-04-23 设计创作，主要内容包括：本发明涉及半导体技术领域,公开了一种谐振器和滤波器。多层结构形成于衬底上,包括压电层、第一电极和第二电极；其中,第一电极和第二电极分别设置在压电层的两侧,所述第一电极包括第一导电层和第二导电层,所述第二电极包括第三导电层和第四导电层,第一电极和第二电极的声阻抗随距离压电层的距离增大而增大；同时,在所述衬底和所述多层结构之间形成有腔体,所述腔体包括位于所述衬底上表面之下的下半腔体和超出所述衬底上表面并向所述多层结构突出的上半腔体。上述谐振器通过设置具有下半腔体和上半腔体的腔体,且下半腔体整体位于衬底上表面之下,上半腔体整体位于衬底上表面之上,形成一种新型的谐振器结构,使谐振器具有较好的性能。(The invention relates to the technical field of semiconductors, and discloses a resonator and a filter. The multilayer structure is formed on the substrate and comprises a piezoelectric layer, a first electrode and a second electrode; the first electrode and the second electrode are respectively arranged on two sides of the piezoelectric layer, the first electrode comprises a first conducting layer and a second conducting layer, the second electrode comprises a third conducting layer and a fourth conducting layer, and acoustic impedance of the first electrode and the second electrode is increased along with increasing distance from the piezoelectric layer; meanwhile, a cavity is formed between the substrate and the multilayer structure, and the cavity comprises a lower half cavity positioned below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure. The resonator is provided with the cavity with the lower cavity and the upper cavity, the lower cavity is integrally positioned below the upper surface of the substrate, and the upper cavity is integrally positioned on the upper surface of the substrate, so that a novel resonator structure is formed, and the resonator has better performance.)

1. A resonator, comprising:

a substrate;

a piezoelectric layer having a first surface and a second surface;

a first electrode disposed adjacent to the first surface, the first electrode comprising a first conductive layer and a second conductive layer; a first conductive layer disposed adjacent to the piezoelectric layer having a first acoustic impedance; a second conductive layer having a second acoustic impedance greater than the first acoustic impedance, the second conductive layer being disposed on a side of the first conductive layer opposite the piezoelectric layer;

a second electrode disposed adjacent to the second surface, the second electrode comprising a third conductive layer and a fourth conductive layer; a third conductive layer disposed adjacent to the piezoelectric layer having a third acoustic impedance; a fourth conductive layer disposed on a side of the third conductive layer opposite the piezoelectric layer and having a fourth acoustic impedance greater than the third acoustic impedance;

wherein the first conductive layer and the third conductive layer are formed of a first material, and the second conductive layer and the fourth conductive layer are formed of a second material;

and a cavity is formed between the substrate and the multilayer structure, the cavity comprises a lower half cavity positioned below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure, and the multilayer structure comprises the piezoelectric layer, the first electrode and the second electrode.

2. The resonator of claim 1, wherein the first material comprises one of niobium, molybdenum, or an alloy of niobium and molybdenum, and the second material comprises tungsten or iridium.

3. The resonator of claim 1, wherein the piezoelectric layer is made of aluminum scandium nitride (scandium) or Aluminum (AL) with a scandium concentration of 1% to 10%_1-xSc_xN。

4. The resonator of claim 1, further comprising:

a passivation layer disposed on a side of one of the first and second electrodes opposite the piezoelectric layer;

a seed layer disposed on a side of the other of the first electrode and the second electrode opposite the piezoelectric layer.

5. The resonator of claim 4, wherein the passivation layer comprises one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, and boron doped silicon oxide; the seed layer comprises one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide and boron-doped silicon oxide.

6. The resonator according to any of claims 1 to 5, characterized in that the lower half-cavity is enclosed by a bottom wall and a first side wall, the bottom wall is entirely parallel to the substrate surface, and the first side wall is a first rounded curved surface extending from the edge of the bottom wall to the upper surface of the substrate;

the first smooth curved surface comprises a first curved surface and a second curved surface which are in smooth transition connection.

7. The resonator according to claim 6, characterized in that the vertical section of said first curved surface is of an inverted parabolic shape and is located above the plane of said bottom wall;

the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

8. The resonator according to any of claims 1 to 5, characterized in that the upper half cavity is enclosed by a lower side of the multilayer structure, a portion of the multilayer structure corresponding to the upper half cavity is enclosed by a top wall and a second side wall, the second side wall is a second rounded surface extending from an edge of the top wall to an upper surface of the substrate;

the second smooth curved surface comprises a third curved surface and a fourth curved surface which are in smooth transition connection.

9. The resonator according to claim 8, characterized in that the vertical section of said third curved surface is parabolic and is located below the plane of said top wall;

the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

10. A resonator, comprising:

a substrate;

a piezoelectric layer having a first surface and a second surface;

a first electrode disposed adjacent to the first surface, the first electrode comprising a first conductive layer and a second conductive layer; a first conductive layer disposed adjacent to the piezoelectric layer having a first acoustic impedance; a second conductive layer having a second acoustic impedance greater than the first acoustic impedance, the second conductive layer being disposed on a side of the first conductive layer opposite the piezoelectric layer;

a second electrode disposed adjacent to the second surface;

a passivation layer disposed on a side of one of the first and second electrodes opposite the piezoelectric layer;

a seed layer disposed on a side of the other of the first electrode and the second electrode opposite the piezoelectric layer;

and a cavity is formed between the substrate and the multilayer structure, the cavity comprises a lower half cavity positioned below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure, and the multilayer structure comprises the piezoelectric layer, the first electrode, the second electrode, the seed crystal layer and the passivation layer.

11. The resonator of claim 10, wherein the passivation layer comprises one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, and boron doped silicon oxide, and wherein the seed layer comprises one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, and boron doped silicon oxide.

12. The resonator of claim 10, wherein the first conductive layer comprises one of niobium, molybdenum, or an alloy of niobium and molybdenum, and the second conductive layer comprises tungsten or iridium.

13. The resonator of claim 12, wherein the second electrode comprises a third conductive layer and a fourth conductive layer; a third conductive layer disposed adjacent to the piezoelectric layer having a third acoustic impedance; a fourth conductive layer is disposed on a side of the third conductive layer opposite the piezoelectric layer and has a fourth acoustic impedance greater than the third acoustic impedance.

14. The resonator of claim 10, wherein the piezoelectric layer is made of aluminum scandium nitride (scandium) or Aluminum (AL) with a scandium concentration of 1% to 10%_1-xSc_xN。

15. The resonator according to any of claims 10 to 14, characterized in that the lower half-cavity is enclosed by a bottom wall and a first side wall, the bottom wall is entirely parallel to the substrate surface, and the first side wall is a first rounded curved surface extending from the edge of the bottom wall to the upper surface of the substrate;

the first smooth curved surface comprises a first curved surface and a second curved surface which are in smooth transition connection.

16. The resonator according to claim 15, characterized in that the vertical section of the first curved surface is of an inverted parabolic shape and is located above the plane of the bottom wall;

the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

17. The resonator according to any of claims 10-14, characterized in that the upper cavity half is enclosed by a lower side of the multilayer structure, and a portion of the multilayer structure corresponding to the upper cavity half is enclosed by a top wall and a second side wall, and the second side wall is a second rounded surface extending from an edge of the top wall to an upper surface of the substrate;

the second smooth curved surface comprises a third curved surface and a fourth curved surface which are in smooth transition connection.

18. The resonator according to claim 17, characterized in that the vertical section of said third curved surface is parabolic and is located below the plane of said top wall;

the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

19. A semiconductor device comprising the resonator of any one of claims 1 to 18.

Technical Field

The invention relates to the technical field of semiconductors, in particular to a resonator and a filter.

Background

Resonators may be used in various electronic applications to implement signal processing functions, for example, some cellular telephones and other communication devices use resonators to implement filters for transmitted and/or received signals. Several different types of resonators may be used depending on different applications, such as Film Bulk Acoustic Resonators (FBARs), coupled resonator filters (SBARs), Stacked Bulk Acoustic Resonators (SBARs), Dual Bulk Acoustic Resonators (DBARs), and solid State Mounted Resonators (SMRs).

A typical acoustic resonator includes an upper electrode, a lower electrode, a piezoelectric material between the upper and lower electrodes, an acoustic reflection structure below the lower electrode, and a substrate below the acoustic reflection structure. The area where the three materials of the upper electrode, the piezoelectric layer and the lower electrode are overlapped in the thickness direction is generally defined as the effective area of the resonator. When a voltage signal with a certain frequency is applied between the electrodes, due to the inverse piezoelectric effect of the piezoelectric material, a sound wave which is vertically transmitted can be generated between the upper electrode and the lower electrode in the effective area, and the sound wave is reflected back and forth between the interface of the upper electrode and the air and the sound reflection structure below the lower electrode and generates resonance under a certain frequency.

In general, the parallel resistance R through the resonator_pSeries resistance R_sQuality factor Q (called "Q factor"), and electromechanical coupling coefficient kt²To evaluate the performance of the resonator. Has higher R_pLower R_sAnd higher Q-factors are considered to have superior performance, it is desirable to improve the performance of the resonator.

Disclosure of Invention

In view of the above, the present invention provides a resonator and a filter including an acoustic redistribution layer.

A first aspect of an embodiment of the present invention provides a resonator, including:

a substrate;

a piezoelectric layer having a first surface and a second surface;

a first electrode disposed adjacent to the first surface, the first electrode comprising a first conductive layer and a second conductive layer; a first conductive layer disposed adjacent to the piezoelectric layer having a first acoustic impedance; a second conductive layer having a second acoustic impedance greater than the first acoustic impedance, the second conductive layer being disposed on a side of the first conductive layer opposite the piezoelectric layer;

a second electrode disposed adjacent to the second surface, the second electrode comprising a third conductive layer and a fourth conductive layer; a third conductive layer disposed adjacent to the piezoelectric layer having a third acoustic impedance; a fourth conductive layer disposed on a side of the third conductive layer opposite the piezoelectric layer and having a fourth acoustic impedance greater than the third acoustic impedance;

wherein the first conductive layer and the third conductive layer are formed of a first material, and the second conductive layer and the fourth conductive layer are formed of a second material;

and a cavity is formed between the substrate and the multilayer structure, the cavity comprises a lower half cavity positioned below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure, and the multilayer structure comprises the piezoelectric layer, the first electrode and the second electrode.

A second aspect of an embodiment of the present invention provides a resonator, including:

a substrate;

a piezoelectric layer having a first surface and a second surface;

a first electrode disposed adjacent to the first surface, the first electrode comprising a first conductive layer and a second conductive layer; a first conductive layer disposed adjacent to the piezoelectric layer having a first acoustic impedance; a second conductive layer having a second acoustic impedance greater than the first acoustic impedance, the second conductive layer being disposed on a side of the first conductive layer opposite the piezoelectric layer;

a second electrode disposed adjacent to the second surface;

a passivation layer disposed on a side of one of the first and second electrodes opposite the piezoelectric layer;

a seed layer disposed on a side of the other of the first electrode and the second electrode opposite the piezoelectric layer;

and a cavity is formed between the substrate and the multilayer structure, the cavity comprises a lower half cavity positioned below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure, and the multilayer structure comprises the piezoelectric layer, the first electrode, the second electrode, the seed crystal layer and the passivation layer.

A third aspect of embodiments of the present invention provides a filter comprising a resonator according to any one of the first and second aspects of embodiments of the present invention.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: according to the embodiment of the invention, the cavity with the lower half cavity and the upper half cavity is arranged, the lower half cavity is integrally positioned below the upper surface of the substrate, the upper half cavity is integrally positioned above the upper surface of the substrate, and the acoustic redistribution layer is also included, namely the first electrode comprises the first conducting layer and the second conducting layer, and the second electrode comprises the third conducting layer and the fourth conducting layer, so that a novel resonator structure is formed, and the novel resonator structure has better performance.

Drawings

FIG. 1 is a top view of a resonator according to an embodiment of the present invention;

FIG. 2(a) is a schematic structural diagram of a resonator according to an embodiment of the present invention;

FIG. 2(b) is a schematic diagram of a resonator according to another embodiment of the present invention;

FIG. 2(c) is an enlarged schematic view of A in FIGS. 2(a) and 2 (b);

fig. 3(a) is a schematic illustration of a multilayer structure without a redistribution layer;

FIG. 3(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 3 (a);

FIG. 4(a) is a schematic view of the multi-layer structure of FIG. 2 (a);

FIG. 4(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 4 (a);

FIG. 5(a) is a schematic illustration of a multilayer structure of a variation of a resonator of an embodiment of the present invention;

FIG. 5(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 5 (a);

FIG. 6(a) is a schematic illustration of a multilayer structure of a variation of a resonator of an embodiment of the present invention;

FIG. 6(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 6 (a);

FIG. 7(a) is a schematic illustration of a multilayer structure of a variation of a resonator of an embodiment of the present invention;

FIG. 7(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 7 (a);

FIG. 8(a) is a schematic illustration of a multilayer structure of a variation of a resonator of an embodiment of the present invention;

FIG. 8(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 8 (a);

FIG. 9(a) is a schematic illustration of a multilayer structure of a variation of a resonator of an embodiment of the present invention;

FIG. 9(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 9 (a);

FIG. 10(a) is a schematic illustration of a multilayer structure of a variation of a resonator of an embodiment of the present invention;

FIG. 10(b) is a graph of the acoustic impedance distribution of the resonator of FIG. 10 (a);

FIG. 11 is a flow chart of a method of making a resonator according to an embodiment of the present invention;

FIG. 12 is a flow chart of yet another method of making a resonator in accordance with an embodiment of the present invention;

fig. 13 is a schematic diagram of a process for manufacturing a resonator according to an embodiment of the invention.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

An embodiment of the present invention provides a resonator including a substrate, a piezoelectric layer, a first electrode, and a second electrode.

Wherein the piezoelectric layer has a first surface and a second surface.

A first electrode disposed adjacent to the first surface, the first electrode comprising a first conductive layer and a second conductive layer; a first conductive layer disposed adjacent to the piezoelectric layer having a first acoustic impedance; a second conductive layer is disposed on a side of the first conductive layer opposite the piezoelectric layer and has a second acoustic impedance greater than the first acoustic impedance.

A second electrode disposed adjacent to the second surface, the second electrode comprising a third conductive layer and a fourth conductive layer; a third conductive layer disposed adjacent to the piezoelectric layer having a third acoustic impedance; a fourth conductive layer is disposed on a side of the third conductive layer opposite the piezoelectric layer and has a fourth acoustic impedance greater than the third acoustic impedance.

Wherein the first conductive layer and the third conductive layer are formed of a first material, and the second conductive layer and the fourth conductive layer are formed of a second material.

And a cavity is formed between the substrate and the multilayer structure, the cavity comprises a lower half cavity positioned below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure, and the multilayer structure comprises the piezoelectric layer, the first electrode and the second electrode.

An Acoustic Redistribution Layer (ARL) is a layer of material added to a multilayer structure to alter the distribution of acoustic energy across the multilayer structure, which results in a change in the electromechanical properties of the resonator, increasing the R of the acoustic resonator_pAnd Q factor, thereby improving the performance of the resonator. The resonator includes a Film Bulk Acoustic Resonator (FBAR), and may also include a Double Bulk Acoustic Resonator (DBAR) or a solid-State Mounted Resonator (SMR), etc.

Referring to fig. 1, the multilayer structure 200 of the resonator is an apodized pentagonal structure (i.e., an asymmetric pentagon) to distribute the density of the sub-oscillation modes over frequency while avoiding strong excitation of either of the sub-oscillation modes at either frequency. In general, the resonator shape is not limited to five sides, but may be a quadrangle, a pentagon, and other shapes.

The resonator comprises a top electrode 210 (hereinafter referred to as second electrode), a connection side 401 and an interconnect 402. The connection side 401 is configured to provide an electrical connection to the interconnect 402. The interconnect 402 provides an electrical signal to the top electrode 201 to excite a desired acoustic wave in the piezoelectric layer (not shown in fig. 1) of the resonator.

In conjunction with fig. 1 and 2(a), first electrode 230 and second electrode 210 are electrically connected to an external circuit via corresponding contact pads (not shown), which are typically formed of a conductive material, such as gold or a gold-tin alloy. Connections (not shown) between the electrodes and contact pads extend laterally outward from the multilayer structure 200, which are typically formed of a conductive material, such as titanium/tungsten/gold.

Referring to fig. 2(a), the resonator may be simplified as including a substrate 100 and a multi-layer structure 200.

The substrate 100 may be formed of silicon, gallium arsenide, indium phosphide, or the like. The multilayer structure 200 is formed over the substrate 100, in one embodiment, a first electrode is disposed below the piezoelectric layer, and a second electrode is disposed above the piezoelectric layer, and the multilayer structure 200 sequentially includes, from bottom to top, the first electrode 230, the piezoelectric layer 220, and the second electrode 210. Wherein a cavity 300 is formed between the substrate 100 and the multilayer structure 200, the cavity 300 comprising a lower half cavity 301 below the upper surface of the substrate 100 and an upper half cavity 302 protruding beyond the upper surface of the substrate 100 and protruding towards the multilayer structure 200.

The first electrode 230 includes a bottom conductive layer 230b and a top conductive layer 230 a. The second electrode 210 includes a bottom conductive layer 210b and a top conductive layer 210 a. The conductive layers of the first and second electrodes 230 and 210 disposed adjacent to the piezoelectric layer 220 are formed of a first material having a relatively low impedance, and the conductive layer disposed on the opposite side of the piezoelectric layer 220 is formed of a second material having a relatively high impedance, see fig. 4 (a). in one embodiment, the bottom conductive layer 230b, and the top conductive layer 210a may be formed of a material having a relatively high acoustic impedance, such as tungsten (W) having an acoustic impedance of about 100MR or iridium (Ir) having an acoustic impedance of about 110MR, while the top conductive layer 230a and the bottom conductive layer 210b may be formed of a material having a relatively low acoustic impedance, such as molybdenum (Mo) having an acoustic impedance of about 65MR, niobium (Nb) having an acoustic impedance of about 42MR, or an alloy of molybdenum (Mo) and niobium (Nb) (having an acoustic impedance of about 42MR to 65MR depending on the particular mix of the two materials in the alloy), and various alternative materials that may be used in the first and second electrodes 230 and 210 may also include aluminum (Al), Platinum (Pt), ruthenium (Ru) or hafnium (Hf).

Generally speaking, acoustic resonators are designed to meet specific characteristic electrical impedance Z0 requirements. The characteristic electrical impedance Z0 is proportional to the acoustic resonator cross-sectional area and inversely proportional to the operating frequency and thickness of the piezoelectric layer. The thickness of the piezoelectric layer is determined mainly by the operating frequency and at the same time by the electromechanical coupling coefficient kt²It is related. Within the limits of applicability, kt²Proportional to the thickness of the piezoelectric layer and inversely proportional to the thickness of the bottom and top electrodes. More specifically, kt²Proportional to the fraction of acoustic energy stored in the piezoelectric layer and inversely proportional to the fraction of acoustic energy stored in the electrodes, and therefore, having a large kt²The acoustic resonator of (a) usually has a thick piezoelectric layer and a thin electrodeAnd an electrode layer. However, in the case of a thick piezoelectric layer, a relatively large cross-sectional area is required to impedance-match the required resonator to a specific Z0, resulting in an increase in the cost of the device. Therefore, where all other factors are equal, it is generally desirable to minimize the cross-sectional area, thereby reducing costs. To minimize cross-sectional area, the piezoelectric layer may be made of a material having a higher kt²Is formed of a material such as aluminum scandium nitride having a scandium concentration of 1% to 10%, thereby maintaining a sufficient kt while the piezoelectric layer is relatively thin²。

However, this design forces a large confinement of the acoustic energy into the electrodes, for R_pAnd Q factor are very disadvantageous, and the use of an acoustic redistribution layer may effectively improve R of an acoustic resonator_pAnd Q factor, giving the acoustic resonator better performance.

As in the typical multilayer structure of the resonator shown in fig. 3(a), the first electrode 230 and the second electrode 210 are formed of a single metal, for example, one of W or Mo, and the piezoelectric layer 220 is formed of ALN. The choice of metallic material is based on the specific performance and processing requirements of the acoustic resonator. For example, since the acoustic impedance of W is greater than that of Mo, W will be used to increase kt²As shown in fig. 3(b), because the high acoustic impedance material allows more acoustic energy to be localized in the piezoelectric layer 220. To minimize the resonator, the area of the acoustic resonator will be reduced, which will result in important performance characteristics (e.g., R) of the acoustic resonator_pAnd Q) degradation. At this time, Mo layers are interposed between the first electrode 230 and the piezoelectric layer 220 and between the piezoelectric layer 220 and the second electrode 210, forming an acoustic redistribution layer, as shown in fig. 4 (b). The acoustic impedance increases with increasing distance from the piezoelectric layer 220, which tends to distribute the acoustic energy across the multilayer structure, redistributing a portion of the energy from the outer W layer to the inner Mo layer, thereby still maintaining the same amount of acoustic energy confined in the piezoelectric layer 220, compensating for kt²Degradation due to area reduction.

In practical applications, the acoustic redistribution layer may also replace a portion of the original metal layers of the first electrode 230 and the second electrode 210, respectively, a portion of the original W electrode is replaced with Mo, i.e., 230a and 210b, and the remaining portion of the original W electrode is 230b and 210a, while the thickness of the piezoelectric layer 220 needs to be adjusted to match the original series resonance frequency Fs and the parallel resonance frequency Fp.

In one embodiment, the piezoelectric layer 220 is disposed on top of the first electrode 230, typically AL_1-xSc_xN or aluminum scandium nitride having a scandium concentration of 1% to 10%, but it may be formed of other piezoelectric materials such as aluminum nitride or zinc oxide.

In one embodiment, the multilayer structure further comprises a passivation layer (not shown) and a seed layer (not shown), the passivation layer being disposed on a side of one of the first electrode 230 and the second electrode 210 opposite the piezoelectric layer 220; a seed layer is disposed on a side of the other of the first electrode 230 and the second electrode 210 opposite the piezoelectric layer 220. For example, a passivation layer may be disposed on the second electrode 210 and a seed layer may be disposed between the substrate 100 and the first electrode 230, and meanwhile, a passivation layer may also be disposed between the substrate 100 and the first electrode 230 and a seed layer may be disposed on the second electrode 210.

In one embodiment, the seed layer may be formed of one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, and boron-doped silicon oxide to promote AL_1-xSc_xAnd (4) growing N. The passivation layer may be formed of various types of materials including one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, silicon dioxide, boron-doped silicon oxide, polysilicon, and the like. The thickness of the passivation layer should generally be sufficient to protect the layers of the multilayer structure 200 from chemical reaction with substances that may enter through leaks in the package.

Referring to fig. 2(a), in one embodiment, the lower half cavity 301 is enclosed by a bottom wall 101 and a first sidewall 102, the bottom wall 101 is entirely parallel to the surface of the substrate 100, and the first sidewall 102 is a first rounded curved surface extending from the edge of the bottom wall 101 to the upper surface of the substrate 100.

Wherein, the bottom wall 101 and the first sidewall 102 are both surface walls of the substrate 100. The first side wall 102 is a first smooth curved surface, which can ensure the performance of the resonator cavity without sudden change.

Referring to fig. 2(c), the first smoothly curved surface may include a first curved surface 1021 and a second curved surface 1022 which are smoothly transitionally connected. The first curved surface 1021 and the second curved surface 1022 in smooth transition connection mean that the joint between the first curved surface 1021 and the second curved surface 1022 is free of sudden change, and the first curved surface 1021 and the second curved surface 1022 are also free of sudden change, so that the performance of the resonator cavity can be ensured. Wherein the substrate 100 is composed of many crystals (e.g. silicon crystals), the absence of abrupt changes means that the gap between the individual crystals at the first rounded surface should not be too large to affect the performance of the resonator.

For example, the vertical section of the first curved surface 1021 may be an inverted parabola shape and is located above the plane of the bottom wall 101; the vertical cross-section of the second curved surface 1022 may be parabolic and is located below the plane of the upper surface of the substrate 100. The first curved surface 1021 and the second curved surface 1022 are smoothly connected. Of course, the first curved surface 1021 and the second curved surface 1022 may be curved surfaces having other shapes, and the gap between the crystals at the first smooth curved surface may not affect the performance of the resonator.

In one embodiment, the first round curved surface is smooth as a whole, and the curvature of each point of the first round curved surface 1021 may be smaller than a first preset value. The first preset value can be set according to actual conditions so as to achieve the purpose that gaps among the crystals at the first smooth curved surface do not affect the performance of the resonator. In order to ensure the mechanical and electrical properties of the multilayer structure, the curvature of the smooth curved surface of the transition region is as small as possible, and under the condition that the thickness of the sacrificial layer is constant, the smallest curvature requires that the length of the transition region is increased, which increases the area of the resonator, so the curvature of the transition region and the length of the transition region are optimized. Preferably, the thickness of the cavity 300 may be 1 μm, and the length of the transition region is controlled to be 3 μm to 5 μm, and the multilayer structure grown in the transition region can satisfy the resonator requirement. The transition zone length is the length of the first sidewall 102 in the direction of the dashed line shown in fig. 1.

Referring to fig. 2(a), in one embodiment, the upper cavity half 302 may be surrounded by the lower side of the multi-layer structure 200, and a portion of the lower side of the multi-layer structure 200 corresponding to the upper cavity half 302 includes a top wall 201 and a second side wall 202, and the second side wall 202 is a second rounded surface extending from an edge of the top wall 201 to the upper surface of the substrate 100.

Wherein, the top wall 201 and the second side wall 202 are both lower side walls of the multi-layer structure 200. The second sidewall 202 is a second smooth curved surface, which can ensure the performance of the resonator cavity without sudden change.

Referring to fig. 2(c), the second rounded curved surface may include a third curved surface 2021 and a fourth curved surface 2022 that are rounded to transition. The third curved surface 2021 and the fourth curved surface 2022 which are connected in a smooth transition manner mean that the joint between the third curved surface 2021 and the fourth curved surface 2022 has no abrupt change, and the third curved surface 2021 and the fourth curved surface 2022 are also curved surfaces without abrupt changes, so that the performance of the resonator cavity can be ensured. Wherein, from the crystal perspective, the substrate 100 is composed of many crystals (e.g. silicon crystals), and the absence of abrupt change means that the gap between the respective crystals at the second rounded curved surface should not be too large to affect the performance of the resonator.

For example, the vertical section of the third curved surface 2021 may be parabolic and is located below the plane of the top wall 201; the vertical section of the fourth curved surface 2022 is in an inverted parabolic shape and is located above the plane of the upper surface of the substrate 100. Of course, the third curved surface 2021 and the fourth curved surface 2022 may have other shapes, and the gap between the crystals at the first rounded curved surface may not affect the performance of the resonator.

In one embodiment, the curvature of each point of the second rounded surface 2021 is less than a second predetermined value. The second preset value can be set according to actual conditions so as to achieve the purpose that gaps among the crystals at the second round curved surface do not affect the performance of the resonator.

Further, the top wall 201 also has no abrupt change. The abrupt changes described here are consistent with the aforementioned abrupt changes, and from a crystal standpoint, the multilayer structure 200 is also comprised of many crystals, and the absence of abrupt changes means that the gaps between the individual crystals at the top wall 201 should not be too large to affect the performance of the resonator.

In the above embodiments, the substrate 100 may be a silicon substrate or a substrate made of other materials, the first electrode 230 may be disposed on the piezoelectric layer, and the second electrode 210 is disposed on the piezoelectric layer, which is not described herein again.

According to the resonator, the cavity 300 with the lower half cavity 301 and the upper half cavity 302 is arranged, the lower half cavity 301 is integrally located below the upper surface of the substrate 100, the upper half cavity 302 is integrally located above the upper surface of the substrate 100, and the acoustic redistribution layer is arranged at the same time, so that a novel resonator structure is formed, and the resonator has good performance.

In one embodiment, an acoustic resonator includes a substrate, a piezoelectric layer, a first electrode, a second electrode, a passivation layer, and a seed layer.

The piezoelectric layer has a first surface and a second surface.

A first electrode disposed adjacent to the first surface, the first electrode comprising a first conductive layer and a second conductive layer; a first conductive layer disposed adjacent to the piezoelectric layer having a first acoustic impedance; a second conductive layer is disposed on a side of the first conductive layer opposite the piezoelectric layer and has a second acoustic impedance greater than the first acoustic impedance.

A second electrode disposed adjacent to the second surface.

A passivation layer is disposed on a side of one of the first and second electrodes opposite the piezoelectric layer.

A seed layer is disposed on a side of the other of the first electrode and the second electrode opposite the piezoelectric layer.

Wherein a cavity is formed between the substrate and the multilayer structure, the cavity comprises a lower half cavity below the upper surface of the substrate and an upper half cavity which exceeds the upper surface of the substrate and protrudes towards the multilayer structure, and the multilayer structure comprises the piezoelectric layer, the first electrode, the second electrode, the seed layer and the passivation layer.

Referring to fig. 2(b), in one embodiment, the first electrode 230 is disposed below the piezoelectric layer 220, the second electrode 210 is disposed above the piezoelectric layer 220, and the multi-layer structure 200 sequentially includes, from bottom to top, a seed layer 240, the first electrode 230, the piezoelectric layer 220, the second electrode 210, and a passivation layer 250. Wherein the second electrode 210 includes a bottom conductive layer 210b and a top conductive layer 210 a. The bottom conductive layer 210b of the second electrode 210 disposed adjacent to the piezoelectric layer 220 is formed of a lower impedance material and the top conductive layer 210a disposed on the opposite side of the piezoelectric layer 220 is formed of a higher impedance material. A cavity 300 is formed between the substrate 100 and the multilayer structure 200, the cavity 300 including a lower half cavity 301 located below the upper surface of the substrate 100 and an upper half cavity 302 protruding beyond the upper surface of the substrate 100 and protruding toward the multilayer structure 200.

In one embodiment, bottom conductive layer 210b may be formed of Mo, Nb, or a MoNb alloy, and bottom conductive layer 210b may be formed of W, Ir. Various alternative materials that may be used in the first and second electrodes 230 and 210 may also include aluminum (Al), platinum (Pt), ruthenium (Ru), or hafnium (Hf).

In one embodiment, the seed layer 240 may be formed of one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, and boron-doped silicon oxide to promote AL_1-xSc_xAnd (4) growing N. The passivation layer 250 may be formed of various types of materials including one of aluminum nitride, silicon carbide, silicon nitride, aluminum oxide, silicon dioxide, boron-doped silicon oxide, polysilicon, and the like. The thickness of the passivation layer 250 should generally be sufficient to protect the various layers of the multilayer structure 200 from chemical reaction with substances that may enter through leaks in the package.

In one embodiment, the first electrode 230 includes a bottom conductive layer 230b and a top conductive layer 230 a. The top conductive layer 230a of the first electrode 230 disposed adjacent to the piezoelectric layer is formed of a lower impedance material and the bottom conductive layer 230b disposed on the opposite side of the piezoelectric layer 220 is formed of a higher impedance material.

In one embodiment, the piezoelectric layer 220 is formed from aluminum scandium nitride or AL having a scandium concentration of 1% to 10%_1-xSc_xN。

Referring to fig. 2(b), in one embodiment, the lower half cavity 301 is surrounded by a bottom wall 101 and a first sidewall 102, the bottom wall 101 is entirely parallel to the surface of the substrate 100, and the first sidewall 102 is a first rounded curved surface extending from the edge of the bottom wall 101 to the upper surface of the substrate 100.

Wherein, the bottom wall 101 and the first sidewall 102 are both surface walls of the substrate 100. The first side wall 102 is a first smooth curved surface, which can ensure the performance of the resonator cavity without sudden change.

Referring to fig. 2(c), the first smoothly curved surface may include a first curved surface 1021 and a second curved surface 1022 which are smoothly transitionally connected. The first curved surface 1021 and the second curved surface 1022 in smooth transition connection mean that the joint between the first curved surface 1021 and the second curved surface 1022 is free of sudden change, and the first curved surface 1021 and the second curved surface 1022 are also free of sudden change, so that the performance of the resonator cavity can be ensured. Wherein the substrate 100 is composed of many crystals (e.g. silicon crystals), the absence of abrupt changes means that the gap between the individual crystals at the first rounded surface should not be too large to affect the performance of the resonator.

For example, the vertical section of the first curved surface 1021 may be an inverted parabola shape and is located above the plane of the bottom wall 101; the vertical cross-section of the second curved surface 1022 may be parabolic and is located below the plane of the upper surface of the substrate 100. The first curved surface 1021 and the second curved surface 1022 are smoothly connected. Of course, the first curved surface 1021 and the second curved surface 1022 may be curved surfaces having other shapes, and the gap between the crystals at the first smooth curved surface may not affect the performance of the resonator.

In one embodiment, the first round curved surface is smooth as a whole, and the curvature of each point of the first round curved surface 1021 may be smaller than a first preset value. The first preset value can be set according to actual conditions so as to achieve the purpose that gaps among the crystals at the first smooth curved surface do not affect the performance of the resonator. In order to ensure the mechanical and electrical properties of the multilayer structure, the curvature of the smooth curved surface of the transition region is as small as possible, and under the condition that the thickness of the sacrificial layer is constant, the smallest curvature requires that the length of the transition region is increased, which increases the area of the resonator, so the curvature of the transition region and the length of the transition region are optimized. Preferably, the thickness of the cavity 300 may be 1 μm, and the length of the transition region is controlled to be 3 μm to 5 μm, and the multilayer structure grown in the transition region can satisfy the resonator requirement. The transition zone length is the length of the first sidewall 102 in the direction of the dashed line shown in fig. 1.

Referring to fig. 2(b), in one embodiment, the upper cavity half 302 may be surrounded by the lower side of the multi-layer structure 200, and a portion of the lower side of the multi-layer structure 200 corresponding to the upper cavity half 302 includes a top wall 201 and a second side wall 202, and the second side wall 202 is a second rounded surface extending from an edge of the top wall 201 to the upper surface of the substrate 100.

Wherein, the top wall 201 and the second side wall 202 are both lower side walls of the multi-layer structure 200. The second sidewall 202 is a second smooth curved surface, which can ensure the performance of the resonator cavity without sudden change.

Referring to fig. 2(c), the second rounded curved surface may include a third curved surface 2021 and a fourth curved surface 2022 that are rounded to transition. The third curved surface 2021 and the fourth curved surface 2022 which are connected in a smooth transition manner mean that the joint between the third curved surface 2021 and the fourth curved surface 2022 has no abrupt change, and the third curved surface 2021 and the fourth curved surface 2022 are also curved surfaces without abrupt changes, so that the performance of the resonator cavity can be ensured. Wherein, from the crystal perspective, the substrate 100 is composed of many crystals (e.g. silicon crystals), and the absence of abrupt change means that the gap between the respective crystals at the second rounded curved surface should not be too large to affect the performance of the resonator.

For example, the vertical section of the third curved surface 2021 may be parabolic and is located below the plane of the top wall 201; the vertical section of the fourth curved surface 2022 is in an inverted parabolic shape and is located above the plane of the upper surface of the substrate 100. Of course, the third curved surface 2021 and the fourth curved surface 2022 may have other shapes, and the gap between the crystals at the first rounded curved surface may not affect the performance of the resonator.

In one embodiment, the curvature of each point of the second rounded surface 2021 is less than a second predetermined value. The second preset value can be set according to actual conditions so as to achieve the purpose that gaps among the crystals at the second round curved surface do not affect the performance of the resonator.

Further, the top wall 201 also has no abrupt change. The abrupt changes described here are consistent with the aforementioned abrupt changes, and from a crystal standpoint, the multilayer structure 200 is also comprised of many crystals, and the absence of abrupt changes means that the gaps between the individual crystals at the top wall 201 should not be too large to affect the performance of the resonator.

In the above embodiments, the substrate 100 may be a silicon substrate or a substrate made of other materials, the first electrode 230 may be disposed on the piezoelectric layer, and the second electrode 210 is disposed on the piezoelectric layer, which is not described herein again.

According to the resonator, the cavity 300 with the lower half cavity 301 and the upper half cavity 302 is arranged, the lower half cavity 301 is integrally located below the upper surface of the substrate 100, the upper half cavity 302 is integrally located above the upper surface of the substrate 100, and the acoustic redistribution layer is arranged at the same time, so that a novel resonator structure is formed, and the resonator has good performance.

Referring to fig. 5(a) and 5(b), in one embodiment, the first electrode 230 is disposed below the piezoelectric layer 220, having two metal layers 230a and 230b with different acoustic impedances, wherein 230b may be formed of Ir or W, 230a may be formed of Mo or Nb, etc., the acoustic impedances of the two metal layers increase with increasing distance from the piezoelectric layer, the second electrode 210 is disposed above the piezoelectric layer 220, having a single metal layer, formed of Ir, W, or Mo, and the piezoelectric layer 220 is formed of ALN.

Fig. 5(a) to 10(b) are alternative configurations of a multilayer structure 200 for use in an acoustic resonator.

Referring to fig. 6(a), the first electrode 230 is disposed under the piezoelectric layer 220, has a single metal layer, and is formed of Ir, W, or Mo. A second electrode 210 is disposed over the piezoelectric layer, having two metal layers 210a and 210b of different acoustic impedances, wherein 210a may be formed of Ir or W, 210b may be formed of Mo or Nb, etc., and the piezoelectric layer 220 is formed of ALN.

Referring to fig. 7(a), the first electrode 230 is disposed under the piezoelectric layer 220, and has two metal layers 230a and 230b having different acoustic impedances, wherein 230b may be formed of Ir or W, 230a may be formed of Mo or Nb, etc., and the acoustic impedances of the two metal layers increase with increasing distance from the piezoelectric layer. The second electrode 210 is disposed above the piezoelectric layer 220, and has two metal layers 210a and 210b having different acoustic impedances, wherein 210a may be formed of Ir or W, 210b may be formed of Mo or Nb, etc., and the piezoelectric layer 220 is formed of ALN. A seed layer 240, formed of ALN, is also disposed between the first electrode 230 and the substrate 100. A passivation layer 250 formed of ALN is disposed on the second electrode 210.

Referring to fig. 8(a), the first electrode 230 is disposed under the piezoelectric layer 220, and has two metal layers 230a and 230b having different acoustic impedances, wherein 230b may be formed of Ir or W, 230a may be formed of Mo or Nb, etc., and the acoustic impedances of the two metal layers increase with increasing distance from the piezoelectric layer. The second electrode 210 is disposed over the piezoelectric layer 220, has a single metal layer, and is formed of Ir, W, or Mo, and the piezoelectric layer 220 is formed of ALN. Meanwhile, a seed layer 240, which is formed of Mo, Nb, or the like, is further disposed between the first electrode 230 and the substrate 100.

Referring to fig. 9(a), the first electrode 230 is disposed under the piezoelectric layer 220, and has two metal layers 230a and 230b having different acoustic impedances, wherein 230b may be formed of Ir or W, 230a may be formed of Mo or Nb, etc., and the acoustic impedances of the two metal layers increase with increasing distance from the piezoelectric layer. The second electrode 210 is disposed above the piezoelectric layer 220, and has two metal layers 210a and 210b having different acoustic impedances, wherein 210a may be formed of Ir or W, 210b may be formed of Mo or Nb, etc., and the piezoelectric layer 220 is formed of ALN. A seed layer 240, which is formed of Mo, Nb, or the like, is further provided between the first electrode 230 and the substrate 100. A passivation layer 250 formed of Mo, Nb, or the like is disposed on the second electrode 210.

Referring to fig. 10(a), a first electrode 230 is disposed below a piezoelectric layer 220, and has two metal layers 230a and 230b having different acoustic impedances, wherein 230b may be formed of Mo, 230a may be formed of Nb or an alloy of Mo and Nb, and the acoustic impedances of the two metal layers increase with increasing distance from the piezoelectric layer. The second electrode 210 is disposed over the piezoelectric layer 220, having two metal layers 210a and 210b with different acoustic impedances, wherein 210a may be formed of Mo, 210b may be formed of Nb or an alloy of Mo and Nb, and the piezoelectric layer 220 is formed of ALN. A seed layer 240, formed of W, is also disposed between the first electrode 230 and the substrate 100. A passivation layer 250, formed of W, is disposed on the second electrode 210.

Wherein the materials in fig. 5(a) through 10(b) are selected for illustrative purposes only, various other combinations are possible in alternative embodiments, which are not limited by the present embodiment.

Referring to fig. 11, an embodiment of the present invention discloses a method for manufacturing a resonator, including the following steps:

step 301, preprocessing the substrate, and changing a preset reaction rate of a preset region part of the substrate, so that the preset reaction rate corresponding to the preset region part is greater than a preset reaction rate corresponding to a non-preset region part.

In this step, the preset reaction rate of the preset region portion of the substrate is made to reach an effect that the preset reaction rate corresponding to the preset region portion is greater than the preset reaction rate corresponding to the non-preset region portion by preprocessing the preset region portion of the substrate, so that the reaction rate of the preset region portion and the reaction rate of the non-preset region portion are different when the preset reaction is performed on the substrate in the subsequent step 302, so as to generate the sacrificial material portion in the preset shape.

Step 302, performing the preset reaction on the substrate to generate a sacrificial material part; the sacrificial material portion includes an upper half located above the upper surface of the substrate and a lower half located below the lower surface of the substrate.

Wherein the lower half part is enclosed by a bottom surface and a first side surface; the bottom surface is entirely parallel to the surface of the substrate, and the first side surface is a first smooth curved surface extending from the edge of the bottom wall to the upper surface of the substrate. The upper half part is surrounded by the lower side surface of the multilayer structure, the part of the multilayer structure corresponding to the upper half part comprises a top surface and a second side surface, and the second side surface is a second smooth curved surface extending from the edge of the top surface to the upper surface of the substrate.

Optionally, the first smooth curved surface includes a first curved surface and a second curved surface which are in smooth transition connection; the vertical section of the first curved surface is in an inverted parabolic shape and is positioned on the plane of the bottom surface; the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

Optionally, the second smooth curved surface includes a third curved surface and a fourth curved surface which are in smooth transition connection; the vertical section of the third curved surface is parabolic and is positioned below the plane of the top surface; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

In one embodiment, the curvature of the first round curved surface is smaller than a first preset value; and the curvature of the second smooth curved surface is smaller than a second preset value.

It can be understood that, since the preset reaction rate corresponding to the preset region part is greater than the preset reaction rate corresponding to the non-preset region part, when the preset reaction is performed on the substrate, the reaction of the preset region part is fast and the reaction of the non-preset region part is slow, so that the sacrificial material part with the preset shape can be generated.

In one embodiment, the step 302 may be implemented by: and placing the substrate in an oxidizing atmosphere for oxidation treatment to obtain a sacrificial material part. Correspondingly, the pretreatment of the substrate in step 301 is a means capable of increasing the oxidation reaction rate of the predetermined region portion of the substrate. The method can be to perform ion implantation in a preset area to improve the oxidation reaction rate of the preset area part of the substrate, or to form a shielding layer with a preset pattern on the substrate to improve the oxidation reaction rate of the preset area part of the substrate.

Of course, in other embodiments, the pretreatment in step 301 may be a means other than an oxidation treatment, and the means may also be to perform ion implantation in a predetermined region to increase the oxidation reaction rate of the predetermined region portion of the substrate, or to form a shielding layer with a predetermined pattern on the substrate to increase the oxidation reaction rate of the predetermined region portion of the substrate.

Step 303, forming a multilayer structure on the sacrificial material layer; the multilayer structure sequentially comprises a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top;

wherein at least one of the upper electrode layer and the lower electrode layer comprises an acoustic redistribution layer;

in one embodiment, the multilayer structure further comprises a passivation layer and a seed layer.

At step 304, the sacrificial material portion is removed to form a resonator.

In this embodiment, the substrate may be a silicon substrate or a substrate made of other materials, which is not limited to this.

According to the resonator manufacturing method, the reaction rate of the preset region part of the substrate is larger than the preset reaction rate corresponding to the non-preset region part by preprocessing the substrate, so that a sacrificial material part in a preset shape can be generated during the preset reaction of the substrate, a multilayer structure is formed on the sacrificial material layer, and finally the sacrificial material part is removed to form the resonator with the special cavity structure.

Referring to fig. 12, an embodiment of the present invention discloses a method for manufacturing a resonator, including the following steps:

step 401, forming a shielding layer on a substrate, wherein the shielding layer covers the substrate except for a preset area, as shown in fig. 13 (a).

In this step, the process of forming the shielding layer on the substrate may include:

forming a shielding medium on the substrate, wherein the shielding layer is used for shielding the substrate except for a preset region from the preset reaction;

and removing the shielding medium corresponding to the preset area to form the shielding layer.

Wherein the shielding medium acts to make the reaction rate of the portion of the substrate covered with the shielding medium lower than the reaction rate of the portion not covered with the shielding medium. Further, the shielding layer may be used to shield a region of the substrate other than the predetermined region from the predetermined reaction.

Step 402, preprocessing the substrate on which the shielding layer is formed, and controlling a part of the substrate corresponding to the preset area to perform a preset reaction to obtain a sacrificial material part; the sacrificial material portion includes an upper half located above the upper surface of the substrate and a lower half located below the lower surface of the substrate.

Wherein the lower half part is enclosed by a bottom surface and a first side surface; the bottom surface is entirely parallel to the surface of the substrate, and the first side surface is a first smooth curved surface extending from the edge of the bottom wall to the upper surface of the substrate. The upper half part is surrounded by the lower side surface of the multilayer structure, the part of the multilayer structure corresponding to the upper half part comprises a top surface and a second side surface, and the second side surface is a second smooth curved surface extending from the edge of the top surface to the upper surface of the substrate.

Optionally, the first smooth curved surface includes a first curved surface and a second curved surface that are connected in a smooth transition manner. For example, the vertical section of the first curved surface is in an inverted parabolic shape and is located above the plane of the bottom surface; the vertical section of the second curved surface is parabolic and is positioned below the plane of the upper surface of the substrate.

Optionally, the second smooth curved surface includes a third curved surface and a fourth curved surface which are in smooth transition connection; the vertical section of the third curved surface is parabolic and is positioned below the plane of the top surface; the vertical section of the fourth curved surface is in an inverted parabolic shape and is positioned on the plane of the upper surface of the substrate.

In one embodiment, the curvature of the first round curved surface is smaller than a first preset value; and the curvature of the second smooth curved surface is smaller than a second preset value.

As an implementable manner, the implementation of step 402 may include: and (c) placing the substrate in an oxidizing atmosphere to perform oxidation treatment, and controlling a part of the substrate corresponding to the preset region to perform oxidation reaction to obtain a sacrificial material part, as shown in fig. 13 (b).

Wherein, the placing the substrate in an oxidizing atmosphere for oxidation treatment may include:

introducing high-purity oxygen to the substrate in a process temperature environment within a preset range, so that an oxide layer is generated on the part, corresponding to the preset area, of the substrate;

after the first preset time, stopping introducing high-purity oxygen to the substrate, and enabling the thickness of an oxide layer on the substrate to reach a preset thickness through one or more modes of wet oxygen oxidation, oxyhydrogen synthesis oxidation and high-pressure water vapor oxidation;

and stopping introducing the wet oxygen to the substrate and introducing high-purity oxygen to the substrate, and completing the oxidation treatment of the substrate after a second preset time.

Wherein the preset range can be 1000-1200 ℃; the first preset time may be 20 minutes to 140 minutes; the preset thickness can be 0.4-4 μm; the second preset time may be 20 minutes to 140 minutes; the flow rate of the high-purity oxygen can be 3L/min to 15L/min.

It should be noted that, one or a combination of several means of pure oxygen, wet oxygen, hydrogen-oxygen synthesis and high-pressure water vapor oxidation is adopted, the appearance of the transition region has certain difference; meanwhile, the selection of the type and the structure of the shielding layer has certain marketing effect on the appearance of the transition region, and the oxidation mode and the type and the structure of the shielding layer are reasonably selected according to the thickness of the multilayer structure and the requirement of the piezoelectric layer on curvature change.

In step 403, the pretreated substrate shielding layer is removed, see fig. 13 (c).

Step 404, forming a multilayer structure on the substrate after the shielding layer is removed, wherein the multilayer structure sequentially comprises a lower electrode layer, a piezoelectric layer and an upper electrode layer from bottom to top, as shown in fig. 13 (d).

Wherein at least one of the upper electrode layer and the lower electrode layer comprises an acoustic redistribution layer.

In one embodiment, the multilayer structure further comprises a passivation layer and a seed layer.

At step 405, the sacrificial material portions are removed, see fig. 13 (e).

In this embodiment, the shielding layer may be a SiN material layer, a SiO2 material layer, a polysilicon material layer, or a multilayer structure formed by mixing two or three materials, and the substrate may be a silicon substrate or a substrate made of other materials, which is not limited in this respect.

In one embodiment, the shielding layer may be SiN or may have a multilayer film structure, and SiN is used as the oxidation shielding layer, so that the shielding effect is better, and the reaction rate difference between the shielding region and the non-shielding region is larger. The shielding medium of the area needing to be made with the resonator can be removed by means of etching or corrosion, etc., the silicon chip is put in an oxidizing atmosphere for oxidation, and the reaction speed of the part with the shielding medium is highThe rate is much different from the reaction rate of the part without shielding medium: the reaction rate of the part without the shielding medium is higher, and the substrate Si reacts with oxygen to form SiO₂SiO produced₂The thickness is increased continuously, the upper surface of the shielding layer is gradually higher than the surface of the shielding medium part, the Si surface of the shielding medium part is gradually lowered, and the surface of the shielding medium part is lowered relatively. A transition region without rate change is formed at the edge of the shielding layer, a smooth curved surface can be formed in the transition region by optimizing an oxidation mode and the type and structure of the shielding layer, and a multi-layer structure of the piezoelectric film containing AlN and the like grows on the smooth curved surface, so that the crystal quality of the piezoelectric film can be ensured.

The embodiment of the invention also discloses a semiconductor device which comprises any one of the resonators and has the beneficial effects of the resonators. For example, the semiconductor device may be a filter.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.