CN117439572A - Surface acoustic wave resonator device, method of forming the same, and filter device - Google Patents
Surface acoustic wave resonator device, method of forming the same, and filter device Download PDFInfo
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- CN117439572A CN117439572A CN202311437154.2A CN202311437154A CN117439572A CN 117439572 A CN117439572 A CN 117439572A CN 202311437154 A CN202311437154 A CN 202311437154A CN 117439572 A CN117439572 A CN 117439572A
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- 229910052814 silicon oxide Inorganic materials 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 5
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02818—Means for compensation or elimination of undesirable effects
- H03H9/02842—Means for compensation or elimination of undesirable effects of reflections
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/125—Driving means, e.g. electrodes, coils
- H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
- H03H9/14538—Formation
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- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
Abstract
A surface acoustic wave resonator device, a method of forming the same, and a surface acoustic wave filter device, the surface acoustic wave resonator device including: a substrate; the reflecting structure is positioned on the substrate and comprises a plurality of reflecting parts which are arranged along a first direction in a discrete manner, the first direction is parallel to the surface of the substrate, and an included angle between the side wall surface of the reflecting part and the surface of the substrate is an acute angle; the first dielectric layer is positioned on the substrate, and the reflecting structure is positioned in the first dielectric layer; a piezoelectric layer on the first dielectric layer, the piezoelectric layer comprising opposing first and second sides, the piezoelectric layer second side facing the first dielectric layer; an interdigital transducer located on a first side of the piezoelectric layer, the interdigital transducer comprising a plurality of interdigital electrodes alternately disposed along a first direction. Clutter of the surface acoustic wave resonance device is suppressed, and Q value is improved.
Description
Technical Field
The present invention relates to the field of semiconductor technologies, and in particular, to a surface acoustic wave resonator device, a method for forming the same, and a surface acoustic wave filter device.
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 radio frequency filter includes a piezoelectric surface acoustic wave (Surface Acoustic Wave, SAW for short), a piezoelectric bulk acoustic wave (Bulk Acoustic Wave, BAW for short), a Micro-Electro-Mechanical System (MEMS for short), an integrated passive device (Integrated Passive Devices, IPD for short), and the like.
The SAW resonator has a high quality factor value (Q value), and is used as an RF filter with low insertion loss (insertion loss) and high out-of-band rejection (out-of-band rejection), that is, as a main RF filter used in wireless communication devices such as mobile phones and base stations. Where the Q value is the quality factor value of the resonator, defined as the center frequency divided by the resonator 3dB bandwidth. SAW filters are typically used at frequencies of 0.4GHz to 2.7GHz.
However, the structure and the process of the existing resonator still cannot achieve the effects of high Q value and noise suppression, so that a simple and low-cost solution needs to be developed.
Disclosure of Invention
The invention solves the technical problem of providing a surface acoustic wave resonance device, a forming method thereof and a surface acoustic wave filter device so as to achieve the effects of improving the Q value of a device and suppressing clutter.
In order to solve the above technical problems, the present invention provides a surface acoustic wave resonator device, including: a substrate; a reflective structure on the substrate, the reflective structure comprising a plurality of reflective portions arranged separately along a first direction, the first direction being parallel to the substrate surface, an included angle between a sidewall surface of the reflective portion and the substrate surface being an acute angle; a first dielectric layer on the substrate, the first dielectric layer covering the top surface and the sidewall surface of the reflective structure; a piezoelectric layer on the first dielectric layer, the piezoelectric layer comprising opposing first and second sides, the piezoelectric layer second side facing the first dielectric layer; an interdigital transducer located on a first side of the piezoelectric layer, the interdigital transducer comprising a plurality of interdigital electrodes alternately disposed along a first direction.
Optionally, the reflecting portions have a first width in the first direction, two adjacent reflecting portions have a first pitch in the first direction, the arrangement of the plurality of reflecting portions along the first direction has a first period, and the first period is a sum of the first width of 2 times and the first pitch of 2 times.
Optionally, the interdigital electrodes have a second width in the first direction, two adjacent interdigital electrodes have a second interval in the first direction, and the arrangement of the interdigital electrodes along the first direction has a second period, wherein the second period is the sum of the second width which is 2 times and the second interval which is 2 times; the ratio of the second period to the first period ranges from 0.5 to 2.
Optionally, the material of the reflecting portion includes polysilicon or monocrystalline silicon.
Alternatively, the shape of the cross section of the reflecting portion in the direction perpendicular to the substrate surface may include a triangle or a trapezoid.
Optionally, the included angle between the side wall surface and the bottom surface of the interdigital electrode ranges from greater than or equal to 45 degrees to less than or equal to 90 degrees.
Optionally, the material of the substrate includes high-resistance silicon, and the resistance value range of the high-resistance silicon material is as follows: 2000 ohms to 10000 ohms.
Optionally, the material of the piezoelectric layer includes lithium tantalate or lithium niobate.
Optionally, the method further comprises: and the second dielectric layer is positioned on the second side of the piezoelectric layer and is bonded with the first dielectric layer.
Optionally, the material of the first dielectric layer includes silicon oxide, silicon nitride or gallium arsenide.
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 substrate; forming a reflecting structure on a substrate, wherein the reflecting structure comprises a plurality of reflecting parts which are arranged along a first direction in a discrete manner, the first direction is parallel to the surface of the substrate, and an included angle between the side wall surface of the reflecting part and the surface of the substrate is an acute angle; forming a first dielectric layer on a substrate, wherein the first dielectric layer covers the top surface and the side wall surface of the reflecting structure; forming a piezoelectric layer comprising opposing first and second sides; bonding the piezoelectric layer to the first dielectric layer, the first dielectric layer being on a second side of the piezoelectric layer; an interdigital transducer is formed on a first side of the piezoelectric layer, the interdigital transducer comprising a plurality of interdigital electrodes alternately disposed along a first direction.
Optionally, the method for forming the reflecting structure includes: forming a reflective material layer on a substrate; forming a patterned mask layer on the reflective material layer; and etching the reflecting material layer by taking the patterned mask layer as a mask, and forming a plurality of discrete reflecting parts on the substrate.
Alternatively, the shape of the cross section of the reflecting portion in the direction perpendicular to the substrate surface may include a triangle or a trapezoid.
Optionally, the method further comprises: forming a second dielectric layer on a second side of the piezoelectric layer, the bonding of the piezoelectric layer to the first dielectric layer including bonding the second dielectric layer to the first dielectric layer.
Correspondingly, the technical scheme of the invention also provides a surface acoustic wave filter device, which comprises: a plurality of surface acoustic wave resonator devices.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
according to the technical scheme, the surface acoustic wave resonance device is provided, the substrate is provided with the reflecting parts which are arranged in a discrete mode along the first direction, and the first dielectric layer on the substrate covers the side wall surface and the top surface of the reflecting part. When the surface acoustic wave resonance device works, the acoustic wave can generate a longitudinal leakage phenomenon, the leaked acoustic wave can propagate to the surface of the substrate, reflection is generated on the surface of the substrate, and the superimposed reflected acoustic wave returns to the resonance area to cause clutter in the passband of the surface acoustic wave resonance device.
Further, the included angle between the side wall surface of the reflecting part and the bottom surface of the reflecting part is an acute angle, the cross section of the reflecting part along the direction perpendicular to the substrate surface comprises a triangle or trapezoid, the included angle range between the side wall surface of the interdigital electrode and the bottom surface is more than or equal to 45 degrees and less than or equal to 90 degrees, and the included angle trend between the side wall surface of the reflecting part and the bottom surface is mutually matched with the included angle trend between the side wall surface of the interdigital electrode and the bottom surface, so that the scattering effect of longitudinally leaked sound waves can be improved, and the influence of the clutter in a passband is further reduced.
Further, the arrangement of the plurality of reflecting portions along the first direction has a first period, the arrangement of the plurality of interdigital electrodes along the first direction has a second period, and the ratio of the second period to the first period ranges from 0.5 to 2. The structure of the reflecting part is matched with the structure of the interdigital electrode, and the ratio range of the second period to the first period is 0.5 to 2, so that the wavelength of the reflecting part is close to the wavelength of the interdigital electrode, and further, bulk acoustic waves can be scattered more effectively, and a better clutter suppression effect is achieved.
Drawings
Fig. 1 to 6 are schematic structural views showing a process of forming a surface wave resonator device according to an embodiment of the present invention;
fig. 7 is a schematic structural view of a surface wave resonator device according to another embodiment of the present invention.
Detailed Description
As described in the background art, the structure and the process manufacturing method of the resonator still cannot achieve the effects of high Q value and noise suppression.
Specifically, two types of surface acoustic wave devices that are mainly used at present are a film type surface acoustic wave filter (Thin Film Surface Acoustic Wave, abbreviated as TF-SAW) and a temperature compensated type surface acoustic wave filter (Temperature Coefficient Surface Acoustic Wave, abbreviated as TC-SAW).
Surface Acoustic Wave (SAW) resonators excite to generate leakage waves on the surface of the piezoelectric layer and propagate to the piezoelectric layer, and the amplitude is rapidly reduced with the increase of the depth of the resonator into the piezoelectric layer; the temperature compensation type surface acoustic wave TC-SAW is characterized in that the structure and the process are improved on the basis of the SAW process, the problem of wave leakage is improved, and the temperature frequency coefficient (temperature coefficient of frequency, TCF for short) and the Q value are improved. The film surface acoustic wave filter (Thin Film Surface Acoustic Wave, TF-SAW) is an optimized TC-SAW with better TCF and RF performance (e.g., electromechanical coupling coefficient, Q value).
The basic structure of the film type surface acoustic wave filter is that Lithium Tantalate (LT) material is used as a piezoelectric layer, an interdigital transducer (Inter-Digital Transducers, IDT for short) is manufactured on the first side of the piezoelectric layer, and the second side of the piezoelectric layer is connected with a bearing substrate through an intermediate layer.
However, applying a voltage across the interdigital electrodes of the interdigital transducer, in addition to exciting a surface acoustic wave propagating parallel to the piezoelectric layer, produces a bulk acoustic wave (bulk acoustic wave) that propagates inward of the piezoelectric layer, which is reflected more regularly (i.e., at a similar angle to the angle of reflection of the reflected wave, and thus more uniform in the direction of reflection) at the contact surface of the second side of the piezoelectric layer with the carrier substrate, and the reflected bulk acoustic wave propagates back to the surface of the first side of the piezoelectric layer to produce parasitic resonance (spurious resonance).
In order to solve the above problems, the technical solution of the present invention provides a surface acoustic wave resonator device, wherein a substrate has reflective parts arranged separately along a first direction, and a first dielectric layer on the substrate covers a side wall surface and a top surface of the reflective parts. When the surface acoustic wave resonance device works, the acoustic wave can generate a longitudinal leakage phenomenon, the leaked acoustic wave can propagate to the surface of the substrate, reflection is generated on the surface of the substrate, and the superimposed reflected acoustic wave returns to the resonance area to cause clutter in the passband of the surface acoustic wave resonance device.
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 1 to 6 are schematic structural views of a surface wave resonator device according to an embodiment of the present invention.
Referring to fig. 1 and 2, fig. 2 is a top view of fig. 1, and fig. 1 is a schematic cross-sectional structure of fig. 2 along a cross-sectional line AA1, providing a substrate 100; a reflective structure including a plurality of reflective parts 101 discretely arranged along a first direction X is formed on a substrate 100, the first direction X being parallel to a surface of the substrate 100, and an angle α between a sidewall surface of the reflective part 101 and a bottom surface of the reflective part 101 is an acute angle.
In this embodiment, the material of the substrate 100 includes high-resistance silicon, and the resistance range of the high-resistance silicon material is: 2000 ohms to 10000 ohms.
The high-resistance silicon substrate has excellent radio frequency performance, and can be subsequently applied to the surface acoustic wave resonance device to improve the Q value of the surface acoustic wave resonance device.
In this embodiment, the material of the reflecting portion 101 includes polysilicon or monocrystalline silicon. The polysilicon or monocrystalline silicon material can not introduce new impurities in the subsequent process of forming the first dielectric layer, so that the quality of the formed first dielectric layer is prevented from being influenced and the pollution to the internal environment of the machine is prevented.
The method for forming the reflecting structure comprises the following steps: forming a reflective material layer (not shown) on the substrate 100; forming a patterned mask layer (not shown) over the reflective material layer; the reflective material layer is etched using the patterned mask layer as a mask, and a plurality of reflective portions 101 are formed separately on the substrate 100.
In this embodiment, the forming process of the reflective material layer includes a physical vapor deposition process. The process of etching the reflective material layer includes a dry etching process capable of better controlling the morphology of the formed reflective portion 101 to obtain a reflective portion 101 of a specific shape.
In the present embodiment, the shape of the cross section of the reflecting portion 101 in the direction perpendicular to the surface of the substrate 100 includes a triangle. The angle α between the side of the triangle and the bottom surface of the reflecting portion 101 is an acute angle. So that when the following semiconductor structure is used as a bearing substrate of the surface acoustic wave resonance device, the reflecting part can be matched with the interdigital electrode to reflect the longitudinal wave back to prevent energy leakage, and plays a role in inhibiting the transverse wave.
In this embodiment, the reflecting portions 101 have a first width w1 in the first direction X, two adjacent reflecting portions 101 have a first spacing d1 in the first direction X, and the plurality of reflecting portions 101 are arranged along the first direction X and have a first period γ1, where the first period γ1 is a sum of the first width w1 of 2 times and the first spacing d1 of 2 times, that is, a first period γ1=2 (w1+d1).
Referring to fig. 3, a first dielectric layer 102 is formed on a substrate 100, the first dielectric layer 102 covers a top surface and a sidewall surface of the reflective structure, and the reflective structure is located in the first dielectric layer 102.
The first dielectric layer 102 provides a planar surface for subsequent bonding with other structures.
The material of the first dielectric layer 102 includes silicon oxide, silicon nitride, or gallium arsenide.
In this embodiment, the material of the first dielectric layer 102 includes silicon oxide.
The process of forming the first dielectric layer 102 includes a chemical vapor deposition process or a furnace tube process. After forming the first dielectric layer 102, the method further includes: and flattening the surface of the first dielectric layer 102 by adopting a chemical mechanical polishing process to reduce the roughness of the surface of the first dielectric layer 102, so as to facilitate the subsequent bonding with the piezoelectric layer.
Referring to fig. 4, a piezoelectric layer 200 is formed, the piezoelectric layer 200 including opposite first and second sides.
In this embodiment, the material of the piezoelectric layer 200 includes lithium tantalate or lithium niobate.
With continued reference to fig. 4, in this embodiment, a second dielectric layer 201 is formed on the second side of the piezoelectric layer 200.
In this embodiment, the material of the second dielectric layer 201 includes silicon oxide.
In other embodiments, the second dielectric layer may not be formed.
Referring to fig. 5 and fig. 6, fig. 6 is a schematic top view of fig. 5 omitting the piezoelectric layer 200, the second dielectric layer 201 and the first dielectric layer 102, fig. 5 is a schematic cross-sectional structure of fig. 6 along the direction of the section line AA1, and the piezoelectric layer 200 and the first dielectric layer 102 are bonded, wherein the first dielectric layer 102 is located on the second side of the piezoelectric layer 200; an interdigital transducer comprising a plurality of interdigital electrodes 202 alternating along a first direction X is formed on a first side of the piezoelectric layer 200.
Bonding the piezoelectric layer 200 to the first dielectric layer 102 includes: bonding the second dielectric layer 201 to the first dielectric layer 102.
In this embodiment, the materials of the second dielectric layer 201 and the first dielectric layer 102 are the same, and covalent bonding is easy to form when the second dielectric layer 201 and the first dielectric layer 102 are bonded together, so as to improve bonding reliability.
In this embodiment, the materials of the second dielectric layer 201 and the first dielectric layer 102 include silicon oxide, which can reduce the Temperature Coefficient (TCF) of the surface acoustic wave resonator device while providing a bonding surface.
In other embodiments, the piezoelectric layer second side is bonded directly to the first dielectric layer.
In this embodiment, after the second side of the piezoelectric layer 200 is bonded to the first dielectric layer 102, the method further includes: thinning the first side of the piezoelectric layer 200; an interdigital transducer is formed on a first side of the thinned piezoelectric layer 200.
In other embodiments, the piezoelectric layer first side can be left un-thinned.
The interdigital electrodes 202 have a second width w2 in the first direction X, two adjacent interdigital electrodes 202 have a second interval d2 in the first direction X, and the plurality of interdigital electrodes 202 are arranged along the first direction X with a second period γ2, where the second period γ2 is a sum of the second width w2 of 2 times and the second interval d2 of 2 times, that is, the second period γ2=2 (w2+d2).
A second period γ2 of the interdigital electrode 202 is a wavelength range.
The reflecting portions 101 have a first width w1 in the first direction X, two adjacent reflecting portions 101 have a first pitch d1 in the first direction X, and the plurality of reflecting portions 101 are arranged along the first direction X to have a first period γ1, where the first period γ1 is a sum of the first width w1 of 2 times and the first pitch d1 of 2 times, that is, a first period γ1=2 (w1+d1).
In this embodiment, the ratio of the second period γ2 to the first period γ1 is in the range of 0.5 to 2. The structure of the reflecting portion 101 matches the structure of the interdigital electrode 202, and the ratio range of the second period γ2 to the first period γ1 is 0.5 to 2, so that the wavelength of the reflecting portion is close to that of the interdigital electrode, and therefore the bulk acoustic wave can be scattered more effectively, and a better clutter suppression effect is achieved.
In this embodiment, the included angle between the sidewall surface and the bottom surface of the interdigital electrode 202 is greater than or equal to 45 degrees and less than or equal to 90 degrees. The interdigitated electrodes 202 of the described range of angles are easier to implement in the process.
The formation method of the interdigital electrode 202 includes: forming a metal material layer (not shown) on a first side of the piezoelectric layer 200; forming a patterned mask layer (not shown) over the metal material layer; and etching the metal material layer by taking the patterned mask layer as a mask until the surface of the piezoelectric layer 200 is exposed, and forming an interdigital transducer on the first side of the piezoelectric layer 200, wherein the interdigital transducer comprises a plurality of interdigital electrodes 202 alternately arranged along the first direction X.
In this embodiment, the included angle α between the side wall surface of the reflecting portion 101 and the bottom surface of the reflecting portion is an acute angle, the cross-section of the reflecting portion 101 along the direction perpendicular to the substrate surface includes a triangle, the range of the included angle between the side wall surface of the interdigital electrode 202 and the bottom surface is greater than or equal to 45 degrees and less than or equal to 90 degrees, and the included angle α between the side wall surface of the reflecting portion 101 and the bottom surface and the trend of the included angle between the side wall surface of the interdigital electrode 202 and the bottom surface cooperate with each other, so that the scattering effect of longitudinally leaked sound waves can be improved, and the influence of clutter in the passband is further reduced.
In this embodiment, the material of the interdigital electrode 202 includes a metal or a metal nitride; the metal comprises: a combination of one or more of copper, aluminum, tungsten, cobalt, nickel, and tantalum; the metal nitride includes one or more combinations of tantalum nitride and titanium nitride.
In the surface acoustic wave resonator device, a substrate 100 is provided with reflective parts 101 which are arranged along a first direction X in a discrete manner, and a first dielectric layer 102 on the substrate 100 covers the side wall surfaces and the top surface of the reflective parts 101. When the surface acoustic wave resonance device works, the acoustic wave can generate a longitudinal leakage phenomenon, the leaked acoustic wave can propagate to the surface of the substrate 100, reflection is generated on the surface of the substrate 100, and the superimposed reflected acoustic wave returns to the resonance area to cause clutter in the passband of the surface acoustic wave resonance device.
Correspondingly, the embodiment of the invention also provides a surface acoustic wave resonance device, and with continued reference to figures 5 and 6,
comprising the following steps: a substrate 100; a reflective structure on the substrate 100, the reflective structure including a plurality of reflective parts 101 discretely arranged along a first direction X, the first direction X being parallel to a surface of the substrate 100, an included angle α between a sidewall surface of the reflective part 101 and a bottom surface of the reflective part 101 being an acute angle; a first dielectric layer 102 on the substrate 100, the reflective structure being located within the first dielectric layer 102; a piezoelectric layer 200 on the first dielectric layer 102, the piezoelectric layer 200 comprising opposite first and second sides, the second side of the piezoelectric layer 200 facing the first dielectric layer 102; an interdigital transducer comprising a plurality of interdigital electrodes 202 alternating along a first direction X is located on a first side of piezoelectric layer 200.
The substrate 100 is provided with reflecting parts 101 which are arranged along a first direction X in a discrete mode, the reflecting parts 101 are positioned in a first dielectric layer 102 on the substrate 100, the semiconductor structure is used as a bearing base of the surface acoustic wave resonance device, and clutter of the surface acoustic wave resonance device is restrained by the reflecting parts.
In this embodiment, the reflecting portions 101 have a first width w1 in the first direction X, two adjacent reflecting portions 101 have a first pitch d1 in the first direction X, and the plurality of reflecting portions 101 are arranged along the first direction X to have a first period γ1, where the first period γ1 is a sum of the first width w1 of 2 times and the first pitch d1 of 2 times.
In this embodiment, the interdigital electrode 202 has a second width w2 in the first direction X, two adjacent interdigital electrodes 202 have a second pitch d2 in the first direction X, and the plurality of interdigital electrodes 202 are arranged along the first direction X with a second period γ2, where the second period γ2 is a sum of the second width w2 of 2 times and the second pitch d2 of 2 times.
In this embodiment, the ratio of the second period γ2 to the first period γ1 is in the range of 0.5 to 2.
In this embodiment, the material of the reflecting portion 101 includes polysilicon or monocrystalline silicon.
In the present embodiment, the shape of the cross section of the reflecting portion 101 in the direction perpendicular to the surface of the substrate 100 includes a triangle.
In this embodiment, the included angle between the sidewall surface and the bottom surface of the interdigital electrode 202 is greater than or equal to 45 degrees and less than or equal to 90 degrees.
In this embodiment, the material of the substrate 100 includes high-resistance silicon, and the resistance range of the high-resistance silicon material is: 2000 ohms to 10000 ohms.
In this embodiment, the material of the piezoelectric layer 200 includes lithium tantalate or lithium niobate.
In this embodiment, further comprising: a second dielectric layer 201 located on a second side of the piezoelectric layer 200, the second dielectric layer 201 being bonded to the first dielectric layer 102.
Correspondingly, the embodiment of the invention further provides a surface acoustic wave filter device, which comprises a plurality of surface acoustic wave resonance devices, and the structure, the materials, the forming process and the technical effects of the surface acoustic wave resonance devices are as shown in the drawings and the text descriptions in fig. 1 to 6, and are not repeated here.
Fig. 7 is a schematic structural view of a surface acoustic wave resonator device in another embodiment of the present invention.
Referring to fig. 7, the surface acoustic wave resonator device in fig. 7 is different from the semiconductor structure in fig. 5 in that the reflection structure includes a plurality of reflection portions 301 arranged separately along a first direction X, the first direction X being parallel to the surface of the substrate 100, the reflection portion 301 being trapezoidal in shape along a cross section perpendicular to the surface of the substrate 100, and an included angle α between a side of the reflection portion 301 and a bottom surface of the reflection portion 301 being an acute angle. So that the reflecting part can cooperate with the interdigital electrode to play a role in inhibiting transverse waves when the subsequent semiconductor structure is used as a bearing substrate of the surface acoustic wave resonance device.
In this embodiment, the reflecting portions 301 have a first width w1 in the first direction X, two adjacent reflecting portions 301 have a first spacing d1 in the first direction X, and the plurality of reflecting portions 301 are arranged along the first direction X and have a first period γ1, where the first period γ1 is a sum of the first width w1 of 2 times and the first spacing d1 of 2 times, that is, a first period γ1=2 (w1+d1).
The process of forming the saw resonator in fig. 7 is referred to the process of forming the saw resonator in fig. 1 to 6, and will not be described herein.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be assessed accordingly to that of the appended claims.
Claims (15)
1. A surface acoustic wave resonator device comprising:
a substrate;
a reflective structure on the substrate, the reflective structure comprising a plurality of reflective portions arranged separately along a first direction, the first direction being parallel to the surface of the substrate, an included angle between a sidewall surface of the reflective portion and a bottom surface of the reflective portion being an acute angle;
a first dielectric layer on the substrate, the first dielectric layer covering the top surface and the sidewall surface of the reflective structure;
a piezoelectric layer on the first dielectric layer, the piezoelectric layer comprising opposing first and second sides, the piezoelectric layer second side facing the first dielectric layer;
an interdigital transducer located on a first side of the piezoelectric layer, the interdigital transducer comprising a plurality of interdigital electrodes alternately disposed along a first direction.
2. The surface acoustic wave resonator apparatus according to claim 1, wherein the reflection sections have a first width in a first direction, two adjacent reflection sections have a first pitch in the first direction, and the arrangement of the plurality of reflection sections in the first direction has a first period that is a sum of the first width of 2 times and the first pitch of 2 times.
3. The surface acoustic wave resonator apparatus according to claim 2, wherein the interdigital electrodes have a second width in the first direction, adjacent two of the interdigital electrodes have a second pitch in the first direction, and an arrangement of the plurality of interdigital electrodes in the first direction has a second period which is a sum of the second width 2 times and the second pitch 2 times; the ratio of the second period to the first period ranges from 0.5 to 2.
4. The surface acoustic wave resonator device according to claim 1, characterized in that the material of the reflecting section comprises polysilicon or monocrystalline silicon.
5. The surface acoustic wave resonator device according to claim 1, wherein the shape of the cross section of the reflecting section in a direction perpendicular to the surface of the substrate comprises a triangle or a trapezoid.
6. The surface acoustic wave resonator device according to claim 1, characterized in that an included angle between a side wall surface and a bottom surface of the interdigital electrode ranges from 45 degrees or more and from 90 degrees or less.
7. The surface acoustic wave resonator device according to claim 1, wherein the material of the substrate comprises high-resistance silicon, and the high-resistance silicon material has a resistance value in a range of: 2000 ohms to 10000 ohms.
8. The surface acoustic wave resonator device according to claim 1, characterized in that the material of the piezoelectric layer comprises lithium tantalate or lithium niobate.
9. The surface acoustic wave resonator apparatus of claim 1, further comprising: and the second dielectric layer is positioned on the second side of the piezoelectric layer and is bonded with the first dielectric layer.
10. The surface acoustic wave resonator device of claim 1, wherein the material of the first dielectric layer comprises silicon oxide, silicon nitride, or gallium arsenide.
11. A method of forming a surface acoustic wave resonator device, comprising:
providing a substrate;
forming a reflective structure on a substrate, wherein the reflective structure comprises a plurality of reflective parts which are arranged along a first direction in a discrete manner, the first direction is parallel to the surface of the substrate, and an included angle between a side wall surface of the reflective part and a bottom surface of the reflective part is an acute angle;
forming a first dielectric layer on a substrate, wherein the first dielectric layer covers the top surface and the side wall surface of the reflecting structure;
forming a piezoelectric layer comprising opposing first and second sides;
bonding the piezoelectric layer to the first dielectric layer, the first dielectric layer being on a second side of the piezoelectric layer; an interdigital transducer is formed on a first side of the piezoelectric layer, the interdigital transducer comprising a plurality of interdigital electrodes alternately disposed along a first direction.
12. The method of forming a surface acoustic wave resonator device of claim 11, wherein the method of forming a reflective structure comprises: forming a reflective material layer on a substrate; forming a patterned mask layer on the reflective material layer; and etching the reflecting material layer by taking the patterned mask layer as a mask, and forming a plurality of discrete reflecting parts on the substrate.
13. The method of forming a surface acoustic wave resonator device according to claim 11, wherein a shape of a cross section of the reflecting section in a direction perpendicular to a surface of the substrate includes a triangle or a trapezoid.
14. The method of forming a surface acoustic wave resonator device of claim 11, further comprising:
forming a second dielectric layer on a second side of the piezoelectric layer, the bonding of the piezoelectric layer to the first dielectric layer including bonding the second dielectric layer to the first dielectric layer.
15. A surface acoustic wave filter device comprising:
a plurality of surface acoustic wave resonator devices as claimed in any one of claims 1 to 10.
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| CN202311437154.2A CN117439572A (en) | 2023-10-31 | 2023-10-31 | Surface acoustic wave resonator device, method of forming the same, and filter device |
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| CN202311437154.2A CN117439572A (en) | 2023-10-31 | 2023-10-31 | Surface acoustic wave resonator device, method of forming the same, and filter device |
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| CN (1) | CN117439572A (en) |
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