CN115037274A

CN115037274A - Surface acoustic wave resonator device and method of forming the same

Info

Publication number: CN115037274A
Application number: CN202210964607.6A
Authority: CN
Inventors: 杨新宇; 汤正杰; 邹雅丽
Original assignee: Changzhou Chengxin Semiconductor Co Ltd
Current assignee: Changzhou Chengxin Semiconductor Co Ltd
Priority date: 2022-08-12
Filing date: 2022-08-12
Publication date: 2022-09-09
Anticipated expiration: 2042-08-12
Also published as: CN115037274B; WO2024032440A1

Abstract

A surface acoustic wave resonator device and a forming method thereof relate to the technical field of semiconductors, wherein the surface acoustic wave resonator device comprises: a piezoelectric substrate; the electrode structure is positioned on the piezoelectric substrate and comprises a first bus and a second bus, the first bus is connected with the first electrode strip, the second bus is connected with the second electrode strip, the first electrode strip comprises a first part and a second part, the second electrode strip comprises a third part and a fourth part, a first spacing area, an overlapping area and a second spacing area are arranged between the first bus and the second bus, the second part and the third part are positioned in the overlapping area, the first part is positioned in the first spacing area, the fourth part is positioned in the second spacing area, and the second part and the third part are respectively larger than the material density of the first part and the material density of the fourth part, so that the wave velocity of the overlapping area is reduced, the wave velocity difference between the overlapping area and the first spacing area and the second spacing area is increased, and the energy leakage of the resonance device from the overlapping area to the first spacing area and the second spacing area during work is reduced, and the performance of the resonance device is improved.

Description

Surface acoustic wave resonator device and method of forming the same

Technical Field

The invention relates to the technical field of semiconductors, in particular to a surface acoustic wave resonance device and a forming method thereof.

Background

A Radio Frequency (RF) front-end chip of a wireless communication device includes a power amplifier, an antenna switch, a Radio Frequency filter, a multiplexer, a low noise amplifier, and the like. The rf filter includes a piezoelectric Acoustic surface Wave (SAW) filter, a Bulk Acoustic Wave (BAW) filter, a Micro-Electro-Mechanical System (MEMS) filter, an Integrated Passive Device (IPD) filter, and the like.

SAW resonators have a high quality factor (Q value), and are manufactured into RF filters with low insertion loss (insertion loss) and high out-of-band rejection (out-band rejection), that is, SAW filters, which are the mainstream RF filters used in wireless communication devices such as mobile phones and base stations. SAW resonators have a negative Temperature Coefficient of Frequency (TCF), i.e., as Temperature increases, the resonant Frequency of the resonator decreases, and as Temperature decreases, the resonant Frequency increases. The reliability and stability of the SAW filter are reduced. In order to improve the characteristic that the resonant frequency of the SAW resonator shifts along with the operating temperature, a temperature compensation layer is added on the piezoelectric substrate, and the temperature compensation layer has a frequency temperature coefficient opposite to that of the piezoelectric substrate. The combination of the two makes the integral frequency temperature coefficient of the resonator tend to zero, and improves the reliability and stability of the filter. Such a SAW resonator including a Temperature compensation layer is called a Temperature Compensated SAW (TC-SAW) resonator, and a filter composed of a TC-SAW resonator is called a TC-SAW filter.

However, the surface acoustic wave resonator device formed in the prior art still has many problems.

Disclosure of Invention

The invention provides a surface acoustic wave resonance device and a forming method thereof, which aim to improve the performance of the surface acoustic wave resonance device.

In order to solve the above problems, a technical solution of the present invention provides a surface acoustic wave resonator device, including: a piezoelectric substrate; an electrode structure on the piezoelectric substrate, the electrode structure including a first bus and a second bus arranged in parallel along a first direction, the first bus connecting a plurality of first electrode strips arranged in parallel along a second direction, the second bus connecting a plurality of second electrode strips arranged in parallel along the second direction, the first direction being perpendicular to the second direction, the first electrode strips and the second electrode strips being disposed alternately, the first electrode strips including a first portion and a second portion connected along the first direction, the second electrode strips including a third portion and a fourth portion connected along the first direction, the second portion and the third portion overlapping in the second direction, a first spacing region, an overlapping region, and a second spacing region arranged along the first direction being provided between the first bus and the second bus, the overlapping region being provided between the first spacing region and the second spacing region, the second portion and the third portion are located in the overlap region, the first portion is located in the first spaced region, the fourth portion is located in the second spaced region, and the material density of the second portion is greater than the material density of the first portion and the fourth portion, respectively, and the material density of the third portion is greater than the material density of the first portion and the fourth portion, respectively.

Optionally, the first portion and the fourth portion are each a single-layer structure; the second portion and the third portion are each a single-layer structure or a multilayer structure.

Optionally, when the second portion and the third portion are of a single-layer structure, the material of the second portion includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium; the material of the third portion comprises: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

Optionally, the material of the first portion comprises: aluminum or an aluminum alloy; the material of the fourth portion comprises: aluminum or an aluminum alloy.

Optionally, the thickness of the second portion is equal to the thickness of the first portion and the thickness of the fourth portion, respectively; the thickness of the third portion is equal to the thickness of the first portion and the fourth portion, respectively.

Optionally, the thickness of the second portion is greater than the thickness of the first portion and the thickness of the fourth portion, respectively; the third portion has a thickness greater than the first and fourth portions, respectively.

Optionally, when the second portion and the third portion are of a multilayer structure, the second portion and the third portion respectively include: the metal layer structure comprises a first metal layer and a second metal layer positioned on the first metal layer, wherein the material density of the first metal layer is greater than that of the second metal layer.

Optionally, the material of the second metal layer includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

Optionally, the material of the second metal layer is the same as the material of the first portion and the fourth portion, respectively.

Optionally, the material of the first metal layer includes: aluminum or an aluminum alloy.

Correspondingly, the technical scheme of the invention also provides a method for forming the surface acoustic wave resonance device, which comprises the following steps: providing a piezoelectric substrate; forming an electrode structure on the piezoelectric substrate, the electrode structure including a first bus and a second bus arranged in parallel in a first direction, the first bus connecting a plurality of first electrode strips arranged in parallel in a second direction, the second bus connecting a plurality of second electrode strips arranged in parallel in the second direction, the first direction being perpendicular to the second direction, the first electrode strips and the second electrode strips being alternately arranged, the first electrode strips including a first portion and a second portion connected in the first direction, the second electrode strips including a third portion and a fourth portion connected in the first direction, the second portion and the third portion overlapping in the second direction, a first spacing region, an overlapping region, and a second spacing region arranged in the first direction between the first bus and the second bus, the overlapping region being located between the first spacing region and the second spacing region, the second portion and the third portion are located in the overlap region, the first portion is located in the first spaced region, the fourth portion is located in the second spaced region, and the material density of the second portion is greater than the material density of the first portion and the fourth portion, respectively, and the material density of the third portion is greater than the material density of the first portion and the fourth portion, respectively.

Optionally, when the second portion and the third portion are of a single-layer structure, the method for forming the first portion, the second portion, the third portion, and the fourth portion includes: forming a first photoresist layer on the first and second spacer regions and on a portion of the overlap region; forming a first electrode material layer on the overlapping area and the first photoresist layer by taking the first photoresist layer as a mask; removing the first photoresist layer and the first electrode material layer on the first photoresist layer by adopting a first stripping process to form the second part and the third part; forming a second photoresist layer on the overlapping region, a portion of the first spacer region, and a portion of the second spacer region, the second photoresist layer covering the second portion and the third portion; forming a second electrode material layer on the first spacing region, the second spacing region and the second photoresist layer by taking the second photoresist layer as a mask; and removing the second photoresist layer and the second electrode material layer on the second photoresist layer by adopting a second stripping process to form the first part and the fourth part.

Optionally, the method for forming the first portion, the first metal layer, the second metal layer, and the fourth portion includes: forming a first electrode material layer on the first spacer region, the overlapping region and the second spacer region; carrying out first patterning treatment on the first electrode material layer to form a first metal layer; forming a second electrode material layer on the first spacing region, the first metal layer and the second spacing region; and carrying out second patterning treatment on the second electrode material layer to form the second metal layer, the first part and the fourth part.

Optionally, the method for forming the first portion, the first metal layer, the second metal layer, and the fourth portion includes: forming a first photoresist layer on the first and second spacer regions and on a portion of the overlap region; forming a first electrode material layer on the overlapping region and the first photoresist layer by taking the first photoresist layer as a mask; removing the first photoresist layer and the first electrode material layer on the first photoresist layer by adopting a first stripping process to form a first metal layer; forming a second photoresist layer on a portion of the first spacer region, a portion of the overlap region, and a portion of the second spacer region; forming a second electrode material layer on the first spacing region, the overlapping region, the second spacing region and the second photoresist layer by taking the second photoresist layer as a mask; and removing the second photoresist layer and the second electrode material layer on the second photoresist layer by adopting a second stripping process to form the second metal layer, the first part and the fourth part.

Optionally, the material of the second metal layer is the same as the material of the first portion and the material of the fourth portion, respectively.

Compared with the prior art, the technical scheme of the invention has the following advantages:

in the surface acoustic wave resonator device according to the technical solution of the present invention, the material density of the second portion is greater than the material density of the first portion and the fourth portion, respectively, and the material density of the third portion is greater than the material density of the first portion and the fourth portion, respectively, so as to reduce the wave velocity of the overlap region, further increase the wave velocity difference between the overlap region and the first spacer region and between the overlap region and the second spacer region, respectively, and reduce the leakage of energy from the overlap region to the first spacer region and the second spacer region during the operation of the resonator device, thereby improving the performance of the resonator device.

Further, the thickness of the second portion is greater than the thickness of the first portion and the fourth portion, respectively; the third portion has a thickness greater than the first and fourth portions, respectively. The wave velocity of the overlapping region can be further reduced, so that the wave velocity difference between the overlapping region and the first spacing region and the wave velocity difference between the overlapping region and the second spacing region are increased, and the leakage of energy from the overlapping region to the first spacing region and the second spacing region when the resonance device works is reduced, so that the performance of the resonance device is improved.

In the method for forming a surface acoustic wave resonator device according to the technical scheme of the present invention, the material density of the second portion is respectively greater than the material densities of the first portion and the fourth portion, and the material density of the third portion is respectively greater than the material densities of the first portion and the fourth portion, so as to reduce the wave velocity of the overlapping region, further increase the wave velocity difference between the overlapping region and the first spacing region and between the overlapping region and the second spacing region, and reduce the energy leakage from the overlapping region to the first spacing region and the second spacing region during the operation of the resonator device, thereby improving the performance of the resonator device.

Drawings

Fig. 1 and 2 are schematic structural views of a surface acoustic wave resonator device;

FIGS. 3 to 12 are schematic structural views of steps of a method of forming a surface acoustic wave resonator device in the embodiment of the present invention;

FIGS. 13 to 16 are schematic structural views of steps of a method of forming a surface acoustic wave resonator device according to another embodiment of the present invention;

FIGS. 17 to 24 are schematic structural views of respective steps of a method of forming a surface acoustic wave resonator device according to still another embodiment of the present invention;

fig. 25 is a schematic diagram comparing impedance versus frequency of a surface acoustic wave resonator device according to an embodiment of the present invention and a surface acoustic wave resonator device according to the prior art.

Detailed Description

As described in the background, the surface acoustic wave resonator devices formed in the prior art still have problems. The following detailed description will be made in conjunction with the accompanying drawings.

Fig. 1 and 2 are schematic structural views of a surface acoustic wave resonator device.

Referring to fig. 1 and 2, fig. 2 is a schematic cross-sectional view taken along line a-a of fig. 1, illustrating a piezoelectric substrate 100; an electrode structure on the piezoelectric substrate 100, the electrode structure including a first bus line 101 and a second bus line 102 arranged in parallel along a first direction X, the first bus line 101 connecting a plurality of first electrode strips 103 arranged in parallel along a second direction Y, the second bus line 102 connecting a plurality of second electrode strips 104 arranged in parallel along the second direction Y, the first direction X being perpendicular to the second direction Y, the first electrode strips 103 and the second electrode strips 104 being disposed alternately, the first electrode strips 103 including a first portion 1031 and a second portion 1032 connected along the first direction X, the second electrode strips 104 including a third portion 1041 and a fourth portion 1042 connected along the first direction X, the second portion 1041 and the third portion 1041 overlapping in the second direction Y, a first spacing area a1 arranged along the first direction X between the first bus line 101 and the second bus line 102, An overlap region B1 and a second spacer region a2, the overlap region B1 is located between the first spacer region a1 and the second spacer region a2, the second portion 1032 and the third portion 1041 are located at the overlap region B1, the first portion 1031 is located at the first spacer region a1, the fourth portion 1042 is located at the second spacer region a2, the material density of the second portion 1032 is equal to the material density of the first portion 1031 and the material density of the fourth portion 1042 are respectively equal, and the material density of the third portion 1041 is equal to the material density of the first portion 1031 and the material density of the fourth portion 1042 are respectively equal.

In this embodiment, the present invention further includes: a temperature compensation layer (not shown) on the piezoelectric substrate 100, the temperature compensation layer covering the electrode structure, the temperature compensation layer and the piezoelectric substrate 100 having opposite temperature Frequency shift characteristics, which can reduce the Temperature Coefficient of Frequency (TCF) and tend to 0 ppm/deg.c, thereby improving the characteristic that the operating Frequency of the surface acoustic wave resonator drifts with the operating temperature, and having higher Frequency-temperature stability. A surface acoustic wave resonator device including a temperature compensation layer is referred to as a temperature compensation surface acoustic wave resonator device (i.e., TC-SAW resonator).

In this embodiment, since the arrangement density of the first electrode stripes 103 and the second electrode stripes 104 in the overlapping region B1 is relatively high, the wave velocity in the overlapping region B1 is smaller than the wave velocity in the first spacer region a1 and the second spacer region a2, and therefore, the main frequency energy of the resonant device is bound to the overlapping region B1 by the wave velocity difference between the overlapping region B1 and the first spacer region a1 and the second spacer region a2, so as to form a standing wave.

However, since the material density of the second portion 1032 is equal to the material density of the first portion 1031 and the fourth portion 1042, respectively, and the material density of the third portion 1041 is equal to the material density of the first portion 1031 and the fourth portion 1042, respectively, so that the wave velocity difference between the overlap region B1 and the first spacing region a1 and the second spacing region a2 is small, energy may still leak from the overlap region B1 to the first spacing region a1 and the second spacing region a2 when the resonant device operates, and the performance of the resonant device is affected.

On the basis, the invention provides a surface acoustic wave resonance device and a forming method thereof, wherein the material density of the second part is respectively greater than the material density of the first part and the fourth part, and the material density of the third part is respectively greater than the material density of the first part and the fourth part, so that the wave speed of the overlapping area is reduced, the wave speed difference between the overlapping area and the first interval area and the second interval area is increased, and the energy leakage from the overlapping area to the first interval area and the second interval area during the operation of the resonance device is reduced, so that the performance of the resonance device is improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described herein, and thus the present invention is not limited to the specific embodiments disclosed below.

FIGS. 3 to 12 are schematic structural views of steps of a method of forming a surface acoustic wave resonator device in the embodiment of the present invention; fig. 25 is a schematic diagram comparing impedance versus frequency of a surface acoustic wave resonator device according to an embodiment of the present invention and a surface acoustic wave resonator device according to the prior art.

Referring to fig. 3, a piezoelectric substrate 200 is provided.

The material of the piezoelectric substrate 200 includes: lithium tantalate, lithium niobate, lead zirconate titanate, lead magnesium niobate-lead titanate, aluminum nitride alloy, gallium nitride, or zinc oxide. In the present embodiment, lithium niobate is used as the material of the piezoelectric substrate 200.

In this embodiment, after providing the piezoelectric substrate 200, the method further includes: forming an electrode structure on the piezoelectric substrate 200, the electrode structure including a first bus line and a second bus line arranged in parallel in a first direction, the first bus line connecting a plurality of first electrode strips arranged in parallel in a second direction, the second bus line connecting a plurality of second electrode strips arranged in parallel in the second direction, the first direction being perpendicular to the second direction, the first electrode strips and the second electrode strips being alternately disposed, the first electrode strips including a first portion and a second portion connected in the first direction, the second electrode strips including a third portion and a fourth portion connected in the first direction, the second portion and the third portion overlapping in the second direction, a first spacing region, an overlapping region, and a second spacing region arranged in the first direction between the first bus line and the second bus line, the overlapping region being located between the first spacing region and the second spacing region, the second portion and the third portion are located in the overlap region, the first portion is located in the first spaced region, the fourth portion is located in the second spaced region, and the material density of the second portion is greater than the material density of the first portion and the fourth portion, respectively, and the material density of the third portion is greater than the material density of the first portion and the fourth portion, respectively. Please refer to fig. 4 to fig. 12 for a specific forming process.

In this embodiment, the first portion and the fourth portion are each a single-layer structure; the second portion and the third portion are each a multilayer structure; the second portion and the third portion respectively include: the metal layer structure comprises a first metal layer and a second metal layer positioned on the first metal layer, wherein the material density of the first metal layer is greater than that of the second metal layer.

Referring to fig. 4 and 5, fig. 5 is a schematic cross-sectional view taken along line a-a in fig. 4, and a first photoresist layer 201 is formed on the first and second spacers a1 and a2 and on a portion of the overlap region B1.

It should be noted that the first photoresist layer 201 is also located on a region where the first bus line and the second bus line are subsequently formed on the piezoelectric substrate 200.

Referring to fig. 6, the view directions of fig. 6 and fig. 5 are the same, and a first electrode material layer 202 is formed on the overlap area B1 and the first photoresist layer 201 by using the first photoresist layer 201 as a mask.

In this embodiment, the material of the first electrode material layer 202 is molybdenum; in other embodiments, ruthenium, tungsten, platinum, copper, chromium, magnesium, or scandium may be used as the material of the first electrode material layer.

In this embodiment, the first electrode material layer 202 is formed by a chemical vapor deposition process; in other embodiments, the first electrode material layer may be formed by a chemical physical deposition process.

Referring to fig. 7, a first lift-off process is employed to remove the first photoresist layer 201 and the first electrode material layer 202 on the first photoresist layer 201, so as to form the first metal layer 203.

In this embodiment, since the material of the first electrode material layer 202 is molybdenum, and the first metal layer 203 is formed by the first electrode material layer 202, the material of the first metal layer 203 is also molybdenum; in other embodiments, the material of the first metal layer may also adopt ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

Referring to fig. 8, a second photoresist layer 204 is formed on a portion of the first spacer regions a1, a portion of the overlap region B1, and a portion of the second spacer regions a 2.

Note that the second photoresist layer 204 is not formed on the area where the first bus line and the second bus line are formed on the piezoelectric substrate 200 subsequently.

Referring to fig. 9, a second electrode material layer 205 is formed on the first spacer a1, the overlap region B1, the second spacer a2 and the second photoresist layer 204 by using the second photoresist layer 204 as a mask.

In this embodiment, the material of the second electrode material layer 205 is aluminum; in other embodiments, the material of the second electrode material layer may also adopt an aluminum alloy.

In this embodiment, the second electrode material layer 205 is formed by a chemical vapor deposition process; in other embodiments, the second electrode material layer may be formed by a chemical physical deposition process.

Referring to fig. 10 and 11, fig. 11 is a schematic cross-sectional view taken along line B-B in fig. 10, and a second lift-off process is performed to remove the second photoresist layer 204 and the second electrode material layer 205 on the second photoresist layer 204, so as to form the second metal layer 206, the first portion 207, and the fourth portion 208.

In this embodiment, the first bus 209 and the second bus 210 are formed simultaneously in the process of forming the second metal layer 206, the first portion 207, and the fourth portion 208.

To this end, the electrode structure is formed, the electrode structure includes a first bus 209 and a second bus 210 arranged in parallel along a first direction X, the first bus 209 connects a plurality of first electrode bars 211 arranged in parallel along a second direction Y, the second bus 210 connects a plurality of second electrode bars 212 arranged in parallel along the second direction Y, the first direction X is perpendicular to the second direction Y, the first electrode bars 211 and the second electrode bars 212 are alternately disposed, the first electrode bars 211 include a first portion 207 and a second portion 213 connected along the first direction X, the second electrode bars 212 include a third portion 214 and a fourth portion 208 connected along the first direction X, the second portion 213 and the third portion 214 overlap in the second direction Y, and a first spacing area a1, a second spacing area a1, a third spacing area b, a fourth spacing area b, a third spacing area b, and a fourth spacing area b are arranged along the first direction X, between the first bus 209 and the second bus 210, An overlap region B1 and a second spacer region a2, the overlap region B1 being located between the first spacer region a1 and the second spacer region a2, the second portion 213 and the third portion 214 being located at the overlap region B1, the first portion 207 being located at the first spacer region a1, the fourth portion 208 being located at the second spacer region a2, and the material density of the second portion 213 being greater than the material density of the first portion 207 and the fourth portion 208, respectively, and the material density of the third portion 214 being greater than the material density of the first portion 207 and the fourth portion 208, respectively.

In this embodiment, the first portion 207 and the fourth portion 208 are each a single-layer structure; the second portion 213 and the third portion 214 are each a multilayer structure; the second portion 213 and the third portion 214 respectively include: a first metal layer 203 and a second metal layer 206 on the first metal layer 203, and the material density of the first metal layer 203 is greater than that of the second metal layer 206.

In this embodiment, since the material of the second electrode material layer 205 is aluminum, and the second metal layer 206, the first portion 207, and the fourth portion 208 are formed by the second electrode material layer 205, the material of the second metal layer 206, the first portion 207, and the fourth portion 208 is also aluminum; in other embodiments, the material of the second metal layer, the first portion and the fourth portion may also be an aluminum alloy.

In this embodiment, the first portion 207, the first metal layer 203, the second metal layer 206, and the fourth portion 208 are formed by a lift-off process, which can effectively reduce etching damage to the piezoelectric substrate 200.

In this embodiment, since the material density of the second portion 213 is greater than that of the first portion 207 and the fourth portion 208, respectively, and the material density of the third portion 214 is greater than that of the first portion 207 and the fourth portion 208, respectively, so as to reduce the wave velocity of the overlapping region, further increase the wave velocity difference between the overlapping region B1 and the first spacing region a1 and the second spacing region a2, respectively, and reduce the energy leakage from the overlapping region B1 to the first spacing region a1 and the second spacing region a2 during the operation of the resonance device, so as to improve the performance of the resonance device, specifically, the Qs (electrical Q value) and Qp (acoustic Q value) of the resonance device are significantly improved (as shown in fig. 25).

Referring to fig. 12, fig. 12 and fig. 11 are the same view direction, after the electrode structure is formed, a temperature compensation layer 215 is formed on the piezoelectric substrate 200, and the temperature compensation layer 215 covers the electrode structure.

It should be noted that, in this embodiment, the temperature compensation layer 215 and the piezoelectric substrate 200 have opposite temperature frequency shift characteristics, which can reduce TCF and tend to 0 ppm/degree c, thereby improving the characteristic that the operating frequency of the surface acoustic wave resonator shifts with the operating temperature, and providing higher frequency-temperature stability.

The material of the temperature compensation layer 215 includes: silicon dioxide, silicon oxyfluoride or silicon oxycarbide. In this embodiment, the material of the temperature compensation layer 215 is silicon dioxide.

Fig. 13 to 16 are schematic structural views of steps of a method of forming a surface acoustic wave resonator device according to another embodiment of the present invention.

In the present embodiment, a method of forming a surface acoustic wave resonator device is described on the basis of the above-described embodiments, and is different from the above-described embodiments in that: the first portion 207, the first metal layer 203, the second metal layer 206 and the fourth portion 208 are formed by a patterning process. Which will be described in detail below with reference to the accompanying drawings.

Referring to fig. 13, the view directions of fig. 13 and fig. 5 are the same, and a first electrode material layer 202 is formed on the first spacing region a1, the overlapping region B1, and the second spacing region a 2.

In this embodiment, the first electrode material layer 202 is formed by a chemical vapor deposition process; in other embodiments, the first electrode material layer may be formed by a physical vapor deposition process.

Referring to fig. 14, a first patterning process is performed on the first electrode material layer 202 to form the first metal layer 203.

In this embodiment, the etching process in the first patterning process is a dry etching process.

Referring to fig. 15, a second electrode material layer 205 is formed on the first spacing region a1, the first metal layer 203 and the second spacing region a 2.

Referring to fig. 16 with continued reference to fig. 10, fig. 16 is a schematic cross-sectional view taken along line B-B in fig. 10, and a second patterning process is performed on the second electrode material layer 205 to form the second metal layer 206, the first portion 207, and the fourth portion 208.

In this embodiment, the etching process in the second patterning process is a dry etching process.

Fig. 17 to 24 are schematic structural views of steps of a method of forming a surface acoustic wave resonator device according to an embodiment of the present invention.

In the present embodiment, a method of forming a surface acoustic wave resonator device is described on the basis of the above-described embodiments, and is different from the above-described embodiments in that: the first portion 207, the second portion 213, the third portion 214, and the fourth portion 208 are all of a single-layer structure. Which will be described in detail below with reference to the accompanying drawings.

Referring to fig. 17, in the same view direction as fig. 17 and fig. 5, a first photoresist layer 201 is formed on the first and second spacer regions a1 and a2, and on a portion of the overlap region B1.

It should be noted that the first photoresist layer 201 is also located on a region where the first bus 209 and the second bus 210 are subsequently formed on the piezoelectric substrate 200.

Referring to fig. 18, a first electrode material layer 202 is formed on the overlap region B1 and the first photoresist layer 201 by using the first photoresist layer 201 as a mask.

Referring to fig. 19 and 20, fig. 20 is a schematic cross-sectional view taken along line C-C in fig. 19, and a first lift-off process is performed to remove the first photoresist layer 201 and the first electrode material layer 202 on the first photoresist layer 201 to form the second portion 213 and the third portion 214.

In this embodiment, since the material of the first electrode material layer 202 is molybdenum, and the second portion 213 and the third portion 214 are formed by the first electrode material layer 202, the material of the second portion 213 and the third portion 214 is also molybdenum; in other embodiments, the material of the second portion and the third portion may also be ruthenium, tungsten, platinum, copper, chromium, magnesium, or scandium.

Referring to fig. 21, a second photoresist layer 204 is formed on the overlapping region B1, on a portion of the first spacer region a1, and on a portion of the second spacer region a2, wherein the second photoresist layer 204 covers the second portion 213 and the third portion 214.

It should be noted that the second photoresist layer 204 is not formed on the area where the first bus 209 and the second bus 210 are formed on the piezoelectric substrate 200.

Referring to fig. 22, a second electrode material layer 205 is formed on the first spacers a1, the second spacers a2 and the second photoresist layer 204 by using the second photoresist layer 204 as a mask.

Referring to fig. 23 and 24, fig. 24 is a schematic cross-sectional view taken along line D-D in fig. 23, and a second lift-off process is performed to remove the second photoresist layer 204 and the second electrode material layer 205 on the second photoresist layer 204 to form the first portion 207 and the fourth portion 208.

In this embodiment, the first bus 209 and the second bus 210 are formed simultaneously in the process of forming the first portion 207 and the fourth portion 208.

In this embodiment, since the material of the second electrode material layer 205 is aluminum, and the first portion 207 and the fourth portion 208 are formed by the second electrode material layer 205, the material of the first portion 207 and the fourth portion 208 is also aluminum; in other embodiments, the material of the first portion and the fourth portion may also be an aluminum alloy.

In this embodiment, the first portion 207, the second portion 213, the third portion 214, and the fourth portion 208 are formed by a lift-off process, so that etching damage to the piezoelectric substrate can be effectively reduced.

In the present embodiment, the thickness of the second portion 213 is equal to the thickness of the first portion 207 and the fourth portion 208, respectively; the thickness of the third portion 214 is equal to the thickness of the first portion 207 and the fourth portion 208, respectively.

In other embodiments, the thickness of the second portion is greater than the thickness of the first and fourth portions, respectively; the third portion has a thickness greater than the first and fourth portions, respectively. The wave velocity of the overlapping region can be further reduced, so that the wave velocity difference between the overlapping region and the first spacing region and the wave velocity difference between the overlapping region and the second spacing region are increased, and the leakage of energy from the overlapping region to the first spacing region and the second spacing region when the resonance device works is reduced, so that the performance of the resonance device is improved.

Correspondingly, the embodiment of the invention also provides a surface acoustic wave resonance device, which comprises: a piezoelectric substrate 200; an electrode structure on the piezoelectric substrate 200, the electrode structure including a first bus 209 and a second bus 210 arranged in parallel along a first direction X, the first bus 209 connecting a plurality of first electrode strips 211 arranged in parallel along a second direction Y, the second bus 210 connecting a plurality of second electrode strips 212 arranged in parallel along the second direction Y, the first direction X being perpendicular to the second direction Y, the first electrode strips 211 and the second electrode strips 212 being staggered, the first electrode strips 211 including first portions 207 and second portions 213 connected along the first direction X, the second electrode strips 212 including third portions 214 and fourth portions 208 connected along the first direction X, the second portions 213 and the third portions 214 overlapping in the second direction Y, a first spacer area a1 arranged along the first direction X, a second spacer area a1 arranged along the first direction X, and a second spacer area a1 arranged between the first bus 209 and the second bus 210, An overlap region B1 and a second spacer region a2, the overlap region B1 being located between the first spacer region a1 and the second spacer region a2, the second portion 213 and the third portion 214 being located at the overlap region B1, the first portion 207 being located at the first spacer region a1, the fourth portion 208 being located at the second spacer region a2, and the material density of the second portion 213 being greater than the material density of the first portion 207 and the fourth portion 208, respectively, and the material density of the third portion 214 being greater than the material density of the first portion 207 and the fourth portion 208, respectively.

Since the material density of the second portion 213 is greater than that of the first portion 207 and the fourth portion 208, respectively, and the material density of the third portion 214 is greater than that of the first portion 207 and the fourth portion 208, respectively, so as to reduce the wave velocity of the overlapping region, and further increase the wave velocity difference between the overlapping region B1 and the first spacer region a1 and the second spacer region a2, respectively, and reduce the energy leakage from the overlapping region B1 to the first spacer region a1 and the second spacer region a2 during the operation of the resonance device, so as to improve the performance of the resonance device, specifically, the performance is significantly improved in Qs (electrical Q value) and Qp (acoustic Q value) values of the resonance device (as shown in fig. 25).

Referring to fig. 23 and 24, in an embodiment, the first portion 207 and the fourth portion 208 are respectively a single-layer structure; the second portion 213 and the third portion 214 each have a single-layer structure.

When the second portion 213 and the third portion 214 have a single-layer structure, the material of the second portion 213 includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium; the material of the third portion 214 includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

The material of the first portion 207 includes: aluminum or an aluminum alloy; the material of the fourth portion 208 includes: aluminum or an aluminum alloy.

With continued reference to fig. 23 and 24, in one embodiment, the thickness of the second portion 213 is equal to the thickness of the first portion 207 and the fourth portion 208, respectively; the thickness of the third portion 214 is equal to the thickness of the first portion 207 and the fourth portion 208, respectively.

In other embodiments, the thickness of the second portion is greater than the thickness of the first and fourth portions, respectively; the third portion has a thickness greater than the first and fourth portions, respectively.

Referring to fig. 10 and 11, in an embodiment, the first portion 207 and the fourth portion 208 are respectively a single-layer structure; the second portion 213 and the third portion 214 each have a multilayer structure.

With continuing reference to fig. 10 and 11, when the second portion 213 and the third portion 214 are of a multi-layer structure, the second portion 213 and the third portion 214 respectively include: a first metal layer 203 and a second metal layer 206 on the first metal layer 203, and the material density of the first metal layer 203 is greater than that of the second metal layer 206.

The material of the second metal layer 203 includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

The material of the second metal layer 206 is the same as the material of the first portion 207 and the fourth portion 208, respectively.

The material of the first metal layer 206 includes: aluminum or an aluminum alloy.

It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and scope of the appended claims.

Claims

1. A surface acoustic wave resonator device, comprising:

a piezoelectric substrate;

an electrode structure on the piezoelectric substrate, the electrode structure including a first bus and a second bus arranged in parallel along a first direction, the first bus connecting a plurality of first electrode strips arranged in parallel along a second direction, the second bus connecting a plurality of second electrode strips arranged in parallel along the second direction, the first direction being perpendicular to the second direction, the first electrode strips and the second electrode strips being disposed alternately, the first electrode strips including a first portion and a second portion connected along the first direction, the second electrode strips including a third portion and a fourth portion connected along the first direction, the second portion and the third portion overlapping in the second direction, a first spacing region, an overlapping region, and a second spacing region arranged along the first direction being provided between the first bus and the second bus, the overlapping region being provided between the first spacing region and the second spacing region, the second portion and the third portion are located in the overlap region, the first portion is located in the first spaced region, the fourth portion is located in the second spaced region, and the material density of the second portion is greater than the material density of the first portion and the fourth portion, respectively, and the material density of the third portion is greater than the material density of the first portion and the fourth portion, respectively.

2. A surface acoustic wave resonator device according to claim 1, wherein said first portion and said fourth portion are each of a single-layer structure; the second portion and the third portion are each a single-layer structure or a multilayer structure.

3. A surface acoustic wave resonator device as set forth in claim 2, wherein when said second portion and said third portion are of a single-layer structure, the material of said second portion includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium, or scandium; the material of the third portion comprises: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

4. A surface acoustic wave resonator device as set forth in claim 3, wherein the material of said first portion includes: aluminum or an aluminum alloy; the material of the fourth portion comprises: aluminum or an aluminum alloy.

5. A surface acoustic wave resonator device as set forth in claim 3, wherein the thickness of said second portion is equal to the thickness of said first portion and said fourth portion, respectively; the thickness of the third portion is equal to the thickness of the first and fourth portions, respectively.

6. A surface acoustic wave resonator device as set forth in claim 3, wherein the thickness of said second portion is larger than the thickness of said first portion and said fourth portion, respectively; the third portion has a thickness greater than the first and fourth portions, respectively.

7. A surface acoustic wave resonator device as set forth in claim 2, wherein when said second portion and said third portion are of a multilayer structure, said second portion and said third portion respectively include: the metal layer structure comprises a first metal layer and a second metal layer positioned on the first metal layer, wherein the material density of the first metal layer is greater than that of the second metal layer.

8. A surface acoustic wave resonator device as set forth in claim 7, wherein the material of said first metal layer includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

9. A surface acoustic wave resonator device as set forth in claim 7, wherein the material of said second metal layer is the same as the material of said first portion and said fourth portion, respectively.

10. A surface acoustic wave resonator device as set forth in claim 9, wherein the material of said second metal layer includes: aluminum or an aluminum alloy.

11. A method of forming a surface acoustic wave resonator device, comprising:

providing a piezoelectric substrate;

forming an electrode structure on the piezoelectric substrate, the electrode structure including a first bus and a second bus arranged in parallel in a first direction, the first bus connecting a plurality of first electrode strips arranged in parallel in a second direction, the second bus connecting a plurality of second electrode strips arranged in parallel in the second direction, the first direction being perpendicular to the second direction, the first electrode strips and the second electrode strips being alternately arranged, the first electrode strips including a first portion and a second portion connected in the first direction, the second electrode strips including a third portion and a fourth portion connected in the first direction, the second portion and the third portion overlapping in the second direction, a first spacing region, an overlapping region, and a second spacing region arranged in the first direction between the first bus and the second bus, the overlapping region being located between the first spacing region and the second spacing region, the second portion and the third portion are located in the overlap region, the first portion is located in the first spacer region, the fourth portion is located in the second spacer region, the material density of the second portion is greater than the material density of the first portion and the material density of the fourth portion, respectively, and the material density of the third portion is greater than the material density of the first portion and the material density of the fourth portion, respectively.

12. A method of forming a surface acoustic wave resonator device as set forth in claim 11, wherein said first portion and said fourth portion are each of a single-layer structure; the second portion and the third portion are each a single-layer structure or a multilayer structure.

13. A method of forming a surface acoustic wave resonator device as set forth in claim 12, wherein when said second portion and said third portion are of a single-layer structure, the method of forming said first portion, second portion, third portion, and fourth portion includes: forming a first photoresist layer on the first and second spacer regions and on a portion of the overlap region; forming a first electrode material layer on the overlapping region and the first photoresist layer by taking the first photoresist layer as a mask; removing the first photoresist layer and the first electrode material layer on the first photoresist layer by adopting a first stripping process to form the second part and the third part; forming a second photoresist layer on the overlap region, on a portion of the first spacer region, and on a portion of the second spacer region, the second photoresist layer covering the second portion and the third portion; forming a second electrode material layer on the first spacing region, the second spacing region and the second photoresist layer by taking the second photoresist layer as a mask; and removing the second photoresist layer and the second electrode material layer on the second photoresist layer by adopting a second stripping process to form the first part and the fourth part.

14. A method for forming a surface acoustic wave resonator device as set forth in claim 12, wherein when said second portion and said third portion are of a single-layer structure, the material of said second portion includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium; the material of the third portion comprises: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

15. A method for forming a surface acoustic wave resonator device as set forth in claim 14, wherein the material of said first portion includes: aluminum or an aluminum alloy; the material of the fourth portion comprises: aluminum or an aluminum alloy.

16. A method of forming a surface acoustic wave resonator device as set forth in claim 14, wherein the thickness of said second portion is equal to the thickness of said first portion and the thickness of said fourth portion, respectively; the thickness of the third portion is equal to the thickness of the first and fourth portions, respectively.

17. A method of forming a surface acoustic wave resonator device as set forth in claim 14, wherein the thickness of said second portion is larger than the thickness of said first portion and the thickness of said fourth portion, respectively; the third portion has a thickness greater than the first and fourth portions, respectively.

18. A method of forming a surface acoustic wave resonator device as set forth in claim 11, wherein when said second portion and said third portion are of a multilayer structure, said second portion and said third portion respectively include: the metal layer structure comprises a first metal layer and a second metal layer positioned on the first metal layer, wherein the material density of the first metal layer is greater than that of the second metal layer.

19. A method of forming a surface acoustic wave resonator device as set forth in claim 18, wherein the method of forming the first portion, the first metal layer, the second metal layer, and the fourth portion includes: forming a first electrode material layer on the first spacer region, the overlapping region and the second spacer region; carrying out first patterning treatment on the first electrode material layer to form a first metal layer; forming a second electrode material layer on the first spacing region, the first metal layer and the second spacing region; and carrying out second patterning treatment on the second electrode material layer to form the second metal layer, the first part and the fourth part.

20. A method of forming a surface acoustic wave resonator device as set forth in claim 18, wherein the method of forming the first portion, the first metal layer, the second metal layer, and the fourth portion includes: forming a first photoresist layer on the first and second spacer regions and on a portion of the overlap region; forming a first electrode material layer on the overlapping region and the first photoresist layer by taking the first photoresist layer as a mask; removing the first photoresist layer and the first electrode material layer on the first photoresist layer by adopting a first stripping process to form a first metal layer; forming a second photoresist layer on a part of the first spacer region, a part of the overlapping region and a part of the second spacer region; forming a second electrode material layer on the first spacing region, the overlapping region, the second spacing region and the second photoresist layer by taking the second photoresist layer as a mask; and removing the second photoresist layer and the second electrode material layer on the second photoresist layer by adopting a second stripping process to form the second metal layer, the first part and the fourth part.

21. A method for forming a surface acoustic wave resonator device as claimed in claim 18, wherein the material of said first metal layer includes: molybdenum, ruthenium, tungsten, platinum, copper, chromium, magnesium or scandium.

22. A method of forming a surface acoustic wave resonator device as set forth in claim 18, wherein the material of said second metal layer is the same as the material of said first portion and the material of said fourth portion, respectively.

23. A method for forming a surface acoustic wave resonator device as claimed in claim 22, wherein the material of said second metal layer includes: aluminum or an aluminum alloy.