CN112653417A - Surface acoustic wave resonator and method for manufacturing the same - Google Patents
Surface acoustic wave resonator and method for manufacturing the same Download PDFInfo
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
-
- 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
Abstract
The surface acoustic wave resonator of the present invention comprises: a substrate; a piezoelectric layer formed on the substrate and having a thickness of 0.8 μm to 1.2 μm; and an interdigital electrode having a plurality of electrode fingers formed in the piezoelectric layer, and having a thickness of 300nm to 500nm, a ratio of a width to a pitch of the electrode fingers, i.e., a duty ratio, of 0.4 to 0.6.
Description
Technical Field
The invention relates to a surface acoustic wave resonator and a manufacturing method thereof, wherein the surface acoustic wave resonator can be used for a filter or a mobile phone radio frequency front end, and the manufacturing method can be used for the technical field of manufacturing the surface acoustic wave resonator and a temperature compensation type surface acoustic wave resonator.
Background
Surface Acoustic Wave (SAW) filters are widely used in signal receiver front-ends as well as duplexers and receive filters. The SAW filter integrates low insertion loss and good suppression performance, and can realize wide bandwidth and small volume. In a known SAW filter, an electric input signal is converted into an acoustic wave by an interposed metal interdigital transducer (IDT), and this IDT electrode is widely used in excitation and detection of SAW, and is constituted by a plurality of electrodes periodically arranged and alternately connected to bus bars, and is formed on a piezoelectric substrate. Like standing waves in electromagnetic transmission lines and waveguides, when surface acoustic waves excited by an interdigital transducer enter a reflecting grating placed in a certain period, incident waves and reflected waves are mutually superposed and are transmitted in the reflecting grating in a standing wave mode, and the surface acoustic wave resonator manufactured by the principle has the characteristics of high Q value and low insertion loss.
When an interdigital transducer structure of an existing surface acoustic wave filter is manufactured, a LIFT-OFF process (LIFT-OFF) is generally adopted, namely, negative photoresist is adopted on a substrate to be subjected to exposure and development to form a pattern, then a metal film is deposited on the pattern, a solvent which does not corrode the metal film is used for removing the photoresist, and metal on the photoresist is stripped along with the removal of the photoresist, so that a metal structure with a preset pattern is left. The adjustment frequency of the SAW filter is mainly adjusted depending on the line width of the IDT electrode, i.e., the line width becomes smaller as the frequency becomes higher, e.g., a line width of 1.9G is generally 0.5 μm, and a line width of 3.5G is generally 0.25 μm. With the development of technology, the application frequency of the SAW filter at high frequency, especially in the future 5G era, will become higher and higher, and the requirement for line width is more severe.
Interdigital electrode thickness also has an effect on the propagation characteristics of the SAW and the performance of the SAW device. From SAW theory, it is known that during SAW propagation, a wave is reflected when there is an impedance mismatch. To reduce reflections, the thickness of the interdigitated electrodes should be minimized. However, the resistance of the interdigital electrode is increased sharply due to the excessively small thickness of the interdigital electrode, and the finger breakage phenomenon is likely to occur in the stripping process of the later-stage interdigital electrode preparation, so that the appropriate thickness of the interdigital electrode needs to be selected when designing the structure of the surface acoustic wave resonator.
Documents of the prior art
Patent document
Patent document 1: CN108923763A manufacturing method of IDT copper process of high-frequency SAW
Disclosure of Invention
Technical problem to be solved by the invention
The application frequency of the filter at high frequency, especially in the future 5G era, is higher and higher, the high power can cause the temperature of the filter to rise rapidly, and temperature drift can be generated, so that the device fails. In addition, the design of the filter needs to satisfy high electromechanical coupling coefficient, low frequency temperature coefficient and high Q value at the same time.
However, the surface acoustic wave resonator used in the conventional filter has a problem that the electromechanical coupling coefficient and Q value are lowered and the temperature coefficient of the frequency is increased when the surface acoustic wave resonator is operated at high frequency, high power, and high temperature, thereby affecting the operation performance of the filter. In this regard, there is a need for a temperature compensated surface acoustic filter having a high electromechanical coupling coefficient, a low frequency temperature coefficient, and a high Q value.
In addition, patent document 1 discloses a conventional method for manufacturing an IDT electrode for a high-frequency SAW, which includes: depositing a dielectric material on the piezoelectric material layer to form a first dielectric layer, coating positive photoresist on the first dielectric layer, defining a pattern of a metal filling groove of the IDT electrode through exposure and development, etching the first dielectric layer by adopting a dry etching process to form a film layer shape corresponding to the IDT pattern, removing the positive photoresist, and depositing the IDT electrode. In the method for manufacturing the IDT electrode, the baking temperature of the photoresist at different positions is not controlled in the baking process after exposure, which may cause uneven heating, and when the baking temperature of the photoresist is unevenly distributed, the photoresist may not form straight side walls of the filling groove, which may cause poor shape of the formed IDT electrode, and burrs may be generated on the IDT electrode, which may cause a decrease in the electromechanical coupling coefficient and Q value, thereby affecting the operation performance of the surface acoustic wave resonator.
The present invention has been made to solve the above-described problems, and an object thereof is to provide a surface acoustic wave resonator having a high electromechanical coupling coefficient, a low frequency temperature coefficient, and a high Q value, and a method of manufacturing the surface acoustic wave resonator.
Technical scheme for solving technical problem
The present invention provides a surface acoustic wave resonator, comprising:
a substrate;
a piezoelectric layer formed on the substrate and having a thickness of 0.8 μm to 1.2 μm; and
an interdigital electrode having a plurality of electrode fingers formed in the piezoelectric layer, and the electrode fingers having a thickness of 300nm to 500nm,
the ratio of the width to the spacing of the electrode fingers, i.e. the duty cycle, is 0.4 to 0.6.
Further, in the surface acoustic wave resonator, the thickness of the piezoelectric layer is 1.2 μm, the thickness of the electrode fingers is 300nm, and the duty ratio of the electrode fingers is 0.4.
Further, the surface acoustic wave resonator further includes a first dielectric layer formed on the piezoelectric layer and performing temperature compensation on the piezoelectric layer.
Further, the surface acoustic wave resonator further includes a second dielectric layer formed on the first dielectric layer and protecting the first dielectric layer.
Further, the surface acoustic wave resonator further includes a third dielectric layer formed as an intermediate layer between the substrate and the piezoelectric layer.
In addition, the invention also provides a manufacturing method of the surface acoustic wave resonator, which comprises the following steps:
a step of forming a substrate;
a step of forming a piezoelectric layer having a thickness of 0.8 to 1.2 μm on the substrate;
coating photoresist on the piezoelectric layer, and defining a pattern of the metal filling groove by exposure and development;
etching the metal filling groove on the piezoelectric layer by an etching process;
forming electrode fingers with a thickness of 300nm to 500nm in the metal-filled trench;
a step of removing the photoresist, wherein the photoresist is removed,
the ratio of the width to the spacing of the electrode fingers, i.e. the duty cycle, is 0.4 to 0.6.
Further, in the method for manufacturing the surface acoustic wave resonator, the thickness of the piezoelectric layer is 1.2 μm, the thickness of the electrode fingers is 300nm, and the duty ratio of the electrode fingers is 0.4.
Further, the method for manufacturing a surface acoustic wave resonator further includes: and forming a first dielectric layer on the piezoelectric layer for temperature compensation of the piezoelectric layer.
Further, the method for manufacturing a surface acoustic wave resonator further includes: and forming a second dielectric layer for protecting the first dielectric layer on the first dielectric layer.
Further, in the method of manufacturing a surface acoustic wave resonator, a third dielectric layer is formed as an intermediate layer between the substrate and the piezoelectric layer.
Further, the method for manufacturing the surface acoustic wave resonator further comprises the steps of uniformly baking the photoresist by using a hot plate after exposing the photoresist, and then cooling the photoresist to normal temperature,
and when the photoresist is uniformly baked, the temperature of the hot plate is controlled by uniformly distributed heating points arranged on the hot plate.
Effects of the invention
According to the present invention, it is possible to provide a surface acoustic wave resonator having a high electromechanical coupling coefficient, a low frequency temperature coefficient, and a high Q value, and a method of manufacturing the surface acoustic wave resonator.
Drawings
Fig. 1 is a diagram showing the structure of a surface acoustic wave resonator according to embodiment 1 of the present invention.
Fig. 2 is a flowchart of manufacturing the surface acoustic wave resonator according to embodiment 1 of the present invention.
Fig. 3 is a schematic structural view of a surface acoustic wave resonator according to embodiment 1 of the present invention in a manufacturing process.
Fig. 4 is a structural view showing a hot plate in the case of using a hot plate heating method.
Detailed Description
The surface acoustic wave resonator and the method of manufacturing the same according to the present invention will be described in detail below with reference to the accompanying drawings. In the specification, the same or similar reference numerals denote the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as limiting the invention.
The following describes embodiments of the present invention. In the description of the drawings below, the same or similar reference numerals are given to the same or similar parts. In this connection, it should be noted that the drawings are only schematic views, and the relationship between the thickness and the planar size, the ratio of the thicknesses of the respective layers, and the like are different from the actual case. Therefore, for a specific thickness or size, reference should be made to the following description for judgment. In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In describing the present invention, an embodiment may be provided with multiple figures, and reference numerals for the same components in the same embodiment are not necessarily shown in each figure, but those skilled in the art will understand that when one or more of the figures in the embodiment are described, those skilled in the art will understand that when a particular figure is not indicated, those figures in the embodiment can be understood in combination with other figures in the embodiment.
Embodiment mode 1
[ surface Acoustic wave resonator ]
Fig. 1 is a side view of the structure of a surface acoustic wave resonator according to embodiment 1 of the present invention. The direction of propagation of the surface acoustic wave, i.e., the electrode finger width direction (i.e., the left-right direction in fig. 1), is the x-axis, and the thickness direction of the piezoelectric material layer 101 (i.e., the up-down direction in fig. 1) is the z-axis.
The structure of the surface acoustic wave resonator of the present invention shown in the figure will be explained below with reference to fig. 1.
The surface acoustic wave resonator of the present invention adopts a piezoelectric thin film type structure, and is sequentially laminated from bottom to top with a substrate 105, a third dielectric layer 106, a piezoelectric material layer 101, a first dielectric layer 103, and a second dielectric layer 104, and an interdigital electrode composed of a plurality of electrode fingers 107 is disposed in the piezoelectric material layer 101. Wherein the substrate 105 may be SiC, Al2O3Or a silicon wafer substrate plated with sapphire, the thickness of the substrate 105 being 10-20 μm. The third dielectric layer 106 is made of SiN or SiO laminated on the substrate 1052And the like. The piezoelectric material layer 101 is formed of, for example, lithium tantalate or a lithium tantalate wafer stacked on the third dielectric layer 106. The interdigital electrode has a plurality of electrode fingers 107 made of aluminum disposed within the piezoelectric material layer 101, and the top surfaces of the electrode fingers 107 are flush with the first principal surface a of the piezoelectric material layer 101. The electrode fingers 107 may also be a combination of metal films with Al as the top layer, such as Al/Cu, or Al/Ti/Cu. The plurality of electrode fingers 107 are spaced apart by a spacing w along the x-axis2Are aligned and extend in the y-axis direction (the direction perpendicular to the x-axis and z-axis). The wavelength of the surface acoustic wave propagating in the surface acoustic wave resonator is 1 μm to 2 μm.
In fig. 1, the number of the electrode fingers 107 is 9, and the number of the electrode fingers 107 is only an example and can be changed according to actual situations.
In the x-axis direction, the electrode fingers 107 have the same width as each other, w1(ii) a The electrode fingers 107 are all equally spaced from one another, w2。
The electrode fingers 107 are all equal in length to one another in the y-axis direction.
In the z-axis direction, the electrode fingers 107 are all equal in thickness to one another, and are all d.
Human hairNow follows the thickness t of the piezoelectric material layer 101 of the surface acoustic wave resonator, the thickness d of the interdigital electrode, and the ratio w of the width and pitch of the electrode fingers 1071/w2The electromechanical coupling coefficient may also change. Accordingly, the inventors have found, through intensive studies, that the thickness t, the thickness d of the interdigital electrode, and the ratio w between the width and the pitch of the electrode fingers 107 are changed1/w2The electromechanical coupling coefficient of the surface acoustic wave resonator can be improved.
Specifically, when the thickness t of the piezoelectric material layer 101 is 0.8 μm to 1.2 μm; the thickness d of the electrode fingers 107 is 300nm to 500 nm; the ratio w of the width to the spacing of the electrode fingers 1071/w2That is, when the duty ratio is 0.4 to 0.6, the effect of improving the electromechanical coupling coefficient of the surface acoustic wave resonator is better, and the electromechanical coupling coefficient k at the moment2≥15％。
In particular, the thickness t at the piezoelectric material layer 101 is 1.2 μm; the thickness d of the electrode fingers 107 is 300nm and the ratio w of the width to the pitch of the electrode fingers 1071/w2That is, when the duty ratio is 0.4, the effect of increasing the electromechanical coupling coefficient of the surface acoustic wave resonator is best, and the electromechanical coupling coefficient k at this time is the best2＝25.5％。
By depositing the material as SiO over the layer of piezoelectric material 1012The first dielectric layer 103 serves as a temperature compensation layer for performing temperature compensation on the piezoelectric material layer 101, and the first dielectric layer 103 has a positive frequency temperature coefficient, so that the effects of reducing frequency deviation caused by temperature change and reducing the frequency temperature coefficient can be achieved.
The second dielectric layer 104 made of SiN is deposited above the first dielectric layer 103 to serve as a protective layer, so that the first dielectric layer 103 can be protected.
The substrate 105 has a high acoustic impedance, so that the third dielectric layer 106 formed between the substrate 105 and the piezoelectric material layer 101 has a low acoustic impedance, thereby neutralizing the high acoustic impedance of the substrate 105, constituting a bragg reflection layer, reflecting an acoustic wave leaking to the substrate 105, effectively reflecting the leaked energy to the surface of the piezoelectric material layer, and thereby enabling to improve the Q value of the surface acoustic wave resonator.
Although the surface acoustic wave resonator of embodiment 1 of the present invention includes: the first dielectric layer 103, the second dielectric layer 104, and the third dielectric layer 106, but they are not necessarily included in the structure of the surface acoustic wave resonator, and may be omitted as appropriate.
[ Process for manufacturing surface Acoustic wave resonator ]
Fig. 2 is a flowchart of manufacturing the surface acoustic wave resonator according to embodiment 1 of the present invention.
Fig. 3 is a schematic structural view of a surface acoustic wave resonator according to embodiment 1 of the present invention in a manufacturing process.
As shown in fig. 2 and 3, the present embodiment also provides a method for manufacturing a surface acoustic wave resonator, including the steps of:
step S11: referring to a portion a of fig. 3, a piezoelectric material layer 101 (piezoelectric wafer) is provided, the thickness of the piezoelectric material layer 101 is 1.2 μm, a positioning mark is provided on the bottom surface of the piezoelectric material layer 101, and the piezoelectric material layer 101 is acid-washed and organic-washed with a mixed solution of acetone, sulfuric acid and hydrogen peroxide in sequence.
Step S12: referring to part b of fig. 3, a positive photoresist 102 is coated on the piezoelectric material layer 101. The thickness of the positive photoresist 102 is 1.2 μm.
Step S13: referring to the portion c of fig. 3, the positive photoresist 102 is exposed, then baked, and then introduced into a cold plate at 23 ℃ for cooling after the baking is completed, and finally developed, thereby forming photoresist grooves 102a, wherein the pattern of the metal filling grooves of the IDT electrode is defined by the photoresist grooves 102a, the width of the photoresist grooves 102a is 300nm, and the distance between the photoresist grooves 102a is 750 nm.
Step S14: referring to part d of fig. 3, an IDT metal buried trench 101a is etched under the photoresist groove 102a on the piezoelectric material layer 101 by a dry etching process so that the width of the IDT metal buried trench 101a is equal to the width of the photoresist groove 102a, i.e., 300nm, and the pitch w of the IDT metal buried trench 101a2Equal to 750nm, which is the pitch of the photoresist grooves 102a, and 300nm, which is the depth of the IDT metal buried trench 101 a.
Step S15: referring to section e of FIG. 3, the piezoelectric is sputteredAn IDT metal layer is deposited in the IDT metal filled trench 101a of the material layer 101 to form electrode fingers 107. Width w of electrode finger 1071Equal to the width of the IDT metal buried trench 101a, i.e., 300 nm; the length of the electrode finger 107 is equal to the length of the IDT metal buried trench 101 a; the pitch between the electrode fingers 107 is equal to 750nm, which is the pitch between the IDT metal buried trenches 101 a; the thickness d of the electrode fingers 107 is equal to the depth of the IDT metal buried trench 101a, i.e., 300nm (i.e., the top surfaces of the electrode fingers 107 are flush with the first main surface a of the piezoelectric material layer 101), and the ratio w of the width to the pitch of the electrode fingers 107 is1/w2300nm/750nm is 0.4. The photoresist 102 residue on the piezoelectric material layer 101 is then removed with a cleaning solution at a high temperature.
Step S16: referring to part f of fig. 3, a PVD process is used to deposit SiO on the piezoelectric material layer 1012And the first dielectric layer 103 covers all of the electrode fingers 107.
Step S17: referring to the portion g of fig. 3, the first dielectric layer 103 is polished by a CMP (chemical mechanical polishing) process to thin the first dielectric layer 103, and the thickness of the thinned first dielectric layer 103 is 200 nm.
Step S18: referring to part h of fig. 3, a PVD process is used to deposit a second dielectric layer 104 of SiN as a protective layer on the first dielectric layer 103, and the thickness of the second dielectric layer 104 is 500 nm.
Step S19: referring to part i of fig. 3, a substrate 105 of SiC as a material and 10 μm in thickness is provided, and the substrate 1 is sequentially immersion-cleaned with a mixed solution of acetone, sulfuric acid, and hydrogen peroxide, and after completion of cleaning, cleaned with N2And drying the single crystal Si substrate in an atmosphere.
Step S20: referring to section j of FIG. 3, a PVD process is used to deposit a material that is SiO on the substrate 1052And the thickness of the third dielectric layer 106 is 200nm, and a positioning mark is arranged on the top surface of the third dielectric layer 106.
Step S21: referring to the k part of fig. 3, CMP polishing is performed on the bonding surface of the piezoelectric material layer 101 and the third dielectric layer 106, the third dielectric layer 106 is aligned with the piezoelectric material layer 101 through the positioning mark, after the third dielectric layer 106 is aligned with the piezoelectric material layer 101, the composite layer of the substrate 105 and the third dielectric layer 106, the composite layer of the piezoelectric material layer 101, the first dielectric layer 103, and the second dielectric layer 104 are moved into a bonding apparatus through a fixture, and the composite layer of the substrate 105 and the third dielectric layer 106, the composite layer of the piezoelectric material layer 101, the first dielectric layer 103, and the second dielectric layer 104 are bonded at a low temperature, where the bonding temperature is less than or equal to 200 ℃.
Thereafter, the production of the surface acoustic wave resonator is terminated.
According to the manufacturing process of the surface acoustic wave resonator, the surface acoustic wave resonator is prepared, and simulation tests show that when the thickness of the piezoelectric material layer is 1.2 mu m, the thickness of the electrode finger 7 is 300nm, and the duty ratio of the electrode finger 7 is 0.4, the effects of improving the electromechanical coupling coefficient, reducing the frequency temperature coefficient and improving the Q value of the surface acoustic wave resonator are the greatest.
In step S12, the thickness of the positive photoresist 102 ranges from 1 μm to 2 μm, which can be adjusted according to the product design requirement.
In the step S13, the line width of the photoresist groove 102a is in a range of 200 to 500nm, which can be defined according to the actual product requirement. Heating plate heating is generally used for baking in the photolithography process, and fig. 4 shows the arrangement of heating points 201 disposed on the hot plate 200 when the heating plate heating is used. Referring to fig. 4, in order to ensure temperature uniformity during baking, a heating plate heating method is adopted, as shown in fig. 4, about 29 heating points 201 are provided on the heating plate 200, and a plurality of sensors are provided on the heating plate 200 to detect the temperature of each heating point 201 on the heating plate 200, and the heating points 201 uniformly arranged on the heating plate 200 are independently temperature-controlled according to the detected temperature. The heating condition of the hot plate 200 can be defined according to the actual product requirement, the temperature range of the hot plate 200 is controlled to be 90-120 ℃, the heating time range is controlled to be 1-10 minutes, for example, the heating time is controlled to be 5 minutes at 110 ℃. By utilizing the hot plate for heating, the uniform baking temperature during baking can be ensured, so that the pattern precision and the resolution of photoetching are improved.
In step S15, the IDT metal layer may be deposited by vapor deposition or the like. The thickness d of the electrode fingers 107 can be adjusted according to the design requirements of the product, and the thickness range is set to be 200nm to 500nm in order to facilitate the precise control of the thickness of the IDT electrode structure. In addition, the lengths of the electrode fingers 107 along the y-axis direction may not be equal to each other, the widths of the electrode fingers 107 along the x-axis direction may not be equal to each other, and the thicknesses of the electrode fingers 107 along the z-axis direction may not be equal to each other.
In the step S16, the first dielectric layer 103 may be deposited by CVD or PECVD. By using SiO as material2The first dielectric layer 103 can reduce the frequency temperature coefficient. The thickness of the first dielectric layer 103 can be adjusted within a range of 100-500 nm according to product design requirements.
In the step S18, the second dielectric layer 104 may also be deposited by CVD or PECVD, and the thickness of the second dielectric layer 104 may be adjusted within a range of 500nm to 900nm according to the product design requirement.
In the step S20, the third dielectric layer 106 may be deposited on the substrate 105 by CVD or PECVD, and the thickness of the third dielectric layer 106 may be adjusted within a range of 150nm to 200nm according to product design requirements.
A surface acoustic wave resonator according to the present invention includes: a substrate; a piezoelectric layer formed on the substrate and having a thickness of 0.8 μm to 1.2 μm; and an interdigital electrode having a plurality of electrode fingers formed in the piezoelectric layer, and having a thickness of 300nm to 500nm, and a ratio of a width of the electrode fingers to a pitch, i.e., a duty ratio, of 0.4 to 0.6. By making the thickness of the piezoelectric layer 0.8 μm to 1.2 μm; the thickness of the electrode fingers is 300nm to 500nm, and the ratio of the width of the electrode fingers to the distance, namely the duty ratio, is 0.4 to 0.6, so that the effect of improving the electromechanical coupling coefficient of the surface acoustic wave resonator is better.
Further, a method for manufacturing a surface acoustic wave resonator according to the present invention includes: a step of forming a substrate; a step of forming a piezoelectric layer having a thickness of 0.8 μm to 1.2 μm on a substrate; coating photoresist on the piezoelectric layer, and defining a pattern of the metal filling groove through exposure and development; etching a metal filling groove on the piezoelectric layer by an etching process; forming electrode fingers with a thickness of 300nm to 500nm in the metal filling grooves; and a step of removing the photoresist, wherein the ratio of the width of the electrode fingers to the space, namely, the duty ratio is 0.4 to 0.6. The surface acoustic wave resonator manufactured by the method can improve the effect of improving the electromechanical coupling coefficient of the surface acoustic wave resonator.
It should be noted that the above-mentioned embodiments are only illustrative of the present invention, and should not be construed as limiting the present invention. While specific embodiments of the invention have been described above, it will be appreciated by those skilled in the art that this is by way of example only, and that the scope of the invention is defined by the appended claims. Various changes and modifications to these embodiments may be made by those skilled in the art without departing from the spirit and scope of the invention, and these changes and modifications are within the scope of the invention.
Industrial applicability of the invention
According to the surface acoustic wave resonator and the method of manufacturing the surface acoustic wave resonator of the present invention, a surface acoustic wave resonator having a high electromechanical coupling coefficient, a low frequency temperature coefficient, and a high Q value can be provided. By applying such a surface acoustic wave resonator to a device such as a filter, the performance of the device can be advantageously improved.
Description of the reference symbols
101 piezoelectric material layer
102 photoresist
102 photoresist groove
103 first dielectric layer
104 second dielectric layer
105 substrate
106 third dielectric layer
107 electrode finger
200 hot plate
201 heat the spot.
Claims (11)
1. A surface acoustic wave resonator, comprising:
a substrate;
a piezoelectric layer formed on the substrate and having a thickness of 0.8 μm to 1.2 μm; and
an interdigital electrode having a plurality of electrode fingers formed in the piezoelectric layer, and the electrode fingers having a thickness of 300nm to 500nm,
the ratio of the width to the spacing of the electrode fingers, i.e. the duty cycle, is 0.4 to 0.6.
2. A surface acoustic wave resonator as set forth in claim 1,
the thickness of the piezoelectric layer is 1.2 μm, the thickness of the electrode fingers is 300nm, and the duty cycle of the electrode fingers is 0.4.
3. A surface acoustic wave resonator as set forth in claim 1,
the piezoelectric device further comprises a first dielectric layer which is formed on the piezoelectric layer and is used for temperature compensation of the piezoelectric layer.
4. A surface acoustic wave resonator as set forth in claim 3,
the semiconductor device further comprises a second dielectric layer which is formed on the first dielectric layer and protects the first dielectric layer.
5. A surface acoustic wave resonator as set forth in claim 1,
and a third dielectric layer formed as an intermediate layer between the substrate and the piezoelectric layer.
6. A method for manufacturing a surface acoustic wave resonator, comprising the steps of:
a step of forming a substrate;
a step of forming a piezoelectric layer having a thickness of 0.8 to 1.2 μm on the substrate;
coating photoresist on the piezoelectric layer, and defining a pattern of the metal filling groove by exposure and development;
etching the metal filling groove on the piezoelectric layer by an etching process;
forming electrode fingers with a thickness of 300nm to 500nm in the metal-filled trench;
a step of removing the photoresist, wherein the photoresist is removed,
the ratio of the width to the spacing of the electrode fingers, i.e. the duty cycle, is 0.4 to 0.6.
7. A surface acoustic wave resonator manufacturing method as set forth in claim 6,
the thickness of the piezoelectric layer is 1.2 μm, the thickness of the electrode fingers is 300nm, and the duty cycle of the electrode fingers is 0.4.
8. A surface acoustic wave resonator manufacturing method as set forth in claim 6,
further comprising: and forming a first dielectric layer on the piezoelectric layer for temperature compensation of the piezoelectric layer.
9. A surface acoustic wave resonator manufacturing method as set forth in claim 8,
further comprising: and forming a second dielectric layer for protecting the first dielectric layer on the first dielectric layer.
10. A surface acoustic wave resonator manufacturing method as set forth in claim 6,
and forming a third dielectric layer as an intermediate layer between the substrate and the piezoelectric layer.
11. A surface acoustic wave resonator manufacturing method as set forth in claim 6,
further comprising the working procedures of uniformly baking the photoresist by using a hot plate after exposing the photoresist, and then cooling the photoresist to normal temperature,
and when the photoresist is uniformly baked, the temperature of the hot plate is controlled by uniformly distributed heating points arranged on the hot plate.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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