CN112803911B - Preparation method of surface acoustic wave transducer with temperature compensation function - Google Patents
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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
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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
- H03H2003/023—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 the resonators or networks being of the membrane type
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
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Abstract
The invention discloses a preparation method of a surface acoustic wave transducer with a temperature compensation function, which relates to the field of manufacturing of surface acoustic wave devices and comprises the following steps: preparing an interdigital transducer on a piezoelectric substrate, wherein the interdigital transducer comprises a first interdigital structure and a second interdigital structure which are oppositely and crosswise arranged, and the two interdigital structures are the same and comprise a first interdigital electrode and a second interdigital electrode serving as a sacrificial layer; preparing a first temperature compensation dielectric film on a piezoelectric substrate, wherein the profile of the first temperature compensation dielectric film has the characteristics of protruding above an electrode and flattening above a gap between adjacent electrode fingers; reducing the film thickness of the first temperature compensation dielectric film to the vicinity of the thickness of the first interdigital electrode to form a first temperature compensation dielectric layer; etching and stripping the sacrificial layer; and preparing a second temperature compensation dielectric layer on the surfaces of the first interdigital electrode and the first temperature compensation dielectric layer. The surface morphology of the medium is controlled by utilizing the sacrificial layer technology, the insertion loss is reduced by controlling the double-layer medium, and the performance of the surface acoustic wave transducer is improved.
Description
Technical Field
The invention relates to the field of manufacturing of surface acoustic wave devices, in particular to a surface acoustic wave resonator or filter required during signal processing of wireless communication equipment, and specifically relates to a preparation method of a surface acoustic wave transducer with a temperature compensation function.
Background
Surface acoustic wave (Surface Acoustic Wave, SAW) technology is a gate of radio frequency electronics that combines acoustic, electronic, piezoelectric materials and semiconductor planar processes. Because the SAW transducer works in the radio frequency band, the SAW transducer has the unique advantages of low electric-acoustic conversion loss, flexible design and easy manufacture, thus being widely applied and being an important component part of various SAW devices.
Radio frequency filters play a vital role in communication devices and terminals, whichThe out-of-band interference and noise can be filtered out to meet the requirements of a radio frequency system and a communication protocol on signal to noise ratio, and the development of the communication technology is accompanied with the development of the communication technology, and the technology development of the communication technology has the characteristics of high frequency, low temperature drift, low loss, miniaturization and the like. With the continuous expansion of application range and the rapid development of communication technology, SAW devices are used more and more frequently, and high performance SAW devices are also more and more desired. However, the electroacoustic transducer adopting the conventional technology at present has the problem that frequency drift occurs under the condition of temperature change. Under the current situation that communication frequency bands are increasingly compact, communication equipment is extremely easy to generate frequency-cross abnormality when used in different temperature environments, so that communication signals are poor. Therefore, TCSAW (Temperature Compensated Surface Acoustic Wave) devices with temperature compensation function using SiO are proposed in the International academy 2 The dielectric is filled in the upper layer of IDT of conventional SAW device, but in these schemes is a single layer of SiO 2 The medium has no flexibility in process and design, and limits the development of TCSAW technology.
Disclosure of Invention
The inventor aims at the problems and the technical requirements, and provides a preparation method of a surface acoustic wave transducer with a temperature compensation function, which utilizes a sacrificial layer technology to control the surface morphology of a medium, and reduces the insertion loss and improves the bandwidth of a TCSAW device by controlling a double-layer temperature compensation medium.
The technical scheme of the invention is as follows:
the interdigital transducer comprises a first interdigital structure, a second interdigital structure, a first bus bar and a second bus bar, wherein the first interdigital structure and the second interdigital structure are oppositely arranged in a crossing way, the first bus bar is connected with a comb handle part of the first interdigital structure, the second bus bar is connected with a comb handle part of the second interdigital structure, each interdigital structure is respectively arranged between two adjacent electrode fingers of the other interdigital structure and is not contacted with each other, and an interdigital area is formed between the tail end edge of the first interdigital structure and the tail end edge of the second interdigital structure;
the first interdigital structure and the second interdigital structure have the same structure and comprise a first interdigital electrode and a second interdigital electrode which is arranged on the first interdigital electrode and serves as a sacrificial layer;
and 6, preparing a second temperature compensation medium layer on the surfaces of the first type of interdigital electrodes and the first temperature compensation medium layer, wherein the coverage area of the second temperature compensation medium layer at least comprises the whole interdigital area.
The further technical proposal is that the first interdigital electrode is a single-layer or multi-layer metal electrode layer.
The further technical proposal is that the second type of interdigital electrode is a single-layer metal electrode layer.
The further technical proposal is that the ratio of the width of the interdigital electrode in the interdigital area to the width of the interdigital gap is 1:4-4:1, and the metallization ratio of the interdigital electrode in the interdigital area is 0.2-0.8.
The further technical proposal is that the material of the first type of interdigital electrode comprises at least one of Ti, al, cu, ag, ni, cr, pt, au, W, mo, and the thickness of the first type of interdigital electrode is 3 to 25 percent of the period length of the interdigital electrode of the interdigital transducer.
The further technical proposal is that the material of the second type of interdigital electrode is Ti, al, cu, cr, ni, W, au, pt, znO, al2O3 and SiO 2 One of SiN, siOF, BSG, and the second type of interdigitated electrode has a thickness of 10% -150% of the thickness of the first type of interdigitated electrode, unlike the surface metal material of the first type of interdigitated electrode.
The further technical proposal is that the material of the first temperature compensation dielectric film in the step 3 comprises SiO 2 、BSG、SiOF、SiON、Si 3 N 4 、TeO 2 Except for the first temperature compensation dielectric film above the interdigital electrodes, the thickness of the rest first temperature compensation dielectric films is not lower than that of the first interdigital electrodes, and the height difference from the highest position to the lowest position of the surfaces of the first temperature compensation dielectric films in the gaps between adjacent electrode fingers is less than 25% of the thickness of the first interdigital electrodes.
The further technical scheme is that the thickness of the first temperature compensation dielectric layer in the step 5 is 3% -15% of the period length of the interdigital electrode of the interdigital transducer, and the ratio of the thickness of the first temperature compensation dielectric layer to the thickness of the first interdigital electrode is 1:3-2:1.
The further technical proposal is that the material of the second temperature compensation medium layer comprises SiO 2 、BSG、SiOF、SiON、Si 3 N 4 、TeO 2 The thickness of the second temperature compensation dielectric layer is 10% -40% of the period length of the interdigital electrode of the interdigital transducer.
The piezoelectric substrate is made of a bulk or thin film of quartz, lithium niobate, lithium tantalate, aluminum nitride or zinc oxide.
The beneficial technical effects of the invention are as follows:
the preparation method disclosed by the application can realize that the thickness of the first temperature compensation dielectric layer is equal to the thickness of the interdigital electrode, so that a flattening structure of the dielectric surface is realized. The planarization technology does not need to increase the investment of CMP (Chemical Mechanical Polishing ) equipment, and can also reduce the use of abrasive consumables, thereby reducing the production and processing cost. In conventional TCSAW device processing, the temperature compensating medium is only one layer and the deposition rate is slow. In the application, the two-layer temperature compensation medium is processed in two steps, the process is convenient to control separately, only the first temperature compensation medium layer is required to adopt a slower deposition rate, the thickness can be controlled to be very thin, the slow deposition process is shortened, and the rapid deposition mode can be selected when the second temperature compensation medium layer is deposited, so that the processing time can be greatly reduced, and the production efficiency is improved. In general, the method is easy to popularize on a large scale, and therefore has higher application value.
Drawings
Fig. 1 is a top view of a surface acoustic wave transducer disclosed in embodiment 1 of the present application.
Fig. 2 is a cross-sectional view of the surface acoustic wave transducer disclosed in embodiment 1 of the present application.
Fig. 3 is a top view of a surface acoustic wave transducer disclosed in example 2 of the present application.
Fig. 4 is a cross-sectional view of a surface acoustic wave transducer disclosed in embodiment 2 of the present application.
Fig. 5 is a flow chart of a method of manufacturing a surface acoustic wave transducer as disclosed herein.
Fig. 6 is a diagram showing the steps of the method for manufacturing the surface acoustic wave transducer according to example 1 of the present application.
Fig. 7 is a performance test chart of the surface acoustic wave filter disclosed in embodiment 1 of the present application.
Detailed Description
The following describes the embodiments of the present invention further with reference to the drawings.
Referring to fig. 1-4, the application discloses a surface acoustic wave transducer with a temperature compensation function, which comprises a piezoelectric substrate 1, an interdigital transducer and a first temperature compensation dielectric layer 6a which are arranged on the piezoelectric substrate 1, and a second temperature compensation dielectric layer 6b which is arranged on the first temperature compensation dielectric layer 6a, wherein the piezoelectric substrate 1 is made of a bulk or thin film of quartz, lithium niobate, lithium tantalate, aluminum nitride or zinc oxide. The interdigital transducer comprises a first interdigital electrode I2 and a second interdigital electrode I3 which are arranged in an opposite and crossed way, a first bus bar 4 connected with a comb handle part of the first interdigital electrode I2 and a second bus bar 5 connected with a comb handle part of the second interdigital electrode I3, wherein each interdigital electrode is respectively arranged between two adjacent electrode fingers of the other interdigital electrode and is not contacted with each other. In this application, the material of the interdigital electrodes of the interdigital transducer includes at least one of Ti, al, cu, ag, ni, cr, pt, au, mo.
An interdigital region is formed between the tail end edge of the first interdigital electrode I2 and the tail end edge of the second interdigital electrode I3, the ratio of the interdigital width of the interdigital electrode in the interdigital region to the width of the interdigital gap is 1:4-4:1, the metallization ratio of the interdigital electrode in the interdigital region is 0.2-0.8, and the thickness of the interdigital electrode in the interdigital region is 3-25% of the period length lambda of the interdigital electrode of the interdigital transducer.
Two temperature compensation medium layers 6 are further arranged in the interdigital region on the piezoelectric substrate 1, and the two temperature compensation medium layers 6 completely cover the whole interdigital region. The material of the two temperature compensation dielectric layers 6 comprises SiO 2 BSG (Boron-doped Silicon Glass, borosilicate glass), siOF, siON, si 3 N 4 、TeO 2 At least one of them. The thickness of the first temperature compensation dielectric layer 6a is 3% -15% of the period length lambda of the interdigital electrode of the interdigital transducer, the ratio of the thickness of the first temperature compensation dielectric layer 6a to the thickness of the electrode is 1:3-2:1, and the thickness of the second temperature compensation dielectric layer 6b is 10% -40% of the period length lambda of the interdigital electrode of the interdigital transducer.
The surface acoustic wave device has higher temperature stability by depositing the temperature compensation medium layer on the surface of the interdigital transducer in two steps. And the two layers of temperature compensation media have the characteristic of being freely adjustable, so that the device has greater elasticity in design. The first temperature compensation dielectric layer can be set as a low-stress dielectric, so that the acoustic propagation loss of the device can be reduced, the insertion loss performance of the device is improved, the mechanical damage of the device is reduced, and the reliability of the device is improved. The thickness of the first temperature compensating dielectric layer may be set equal to or different from the thickness of the first type of interdigital electrode, depending on the different preferences of the transducer design. For the surface acoustic wave transducer with the main rayleigh wave mode, the thickness of the first temperature compensation dielectric layer is better as the thickness of the interdigital electrode is closer (for example 1), and for the surface acoustic wave transducer with the main shear wave mode, the effect is better as the thickness of the first temperature compensation dielectric layer and the thickness of the interdigital electrode keep a certain difference (for example 2).
In order to obtain the surface acoustic wave transducer with the temperature compensation function, the application also discloses a preparation method of the surface acoustic wave transducer with the temperature compensation function, a preparation flow chart of the surface acoustic wave transducer is shown in fig. 5, and the preparation method is described through the following two embodiments.
Example 1:
the preparation method of the surface acoustic wave transducer with the temperature compensation function comprises the following steps:
And 2, preparing the interdigital transducer on the piezoelectric substrate 1 through photoetching, evaporation, stripping and other processes.
The interdigital transducer comprises a first interdigital structure, a second interdigital structure, a first bus bar and a second bus bar, wherein the first interdigital structure and the second interdigital structure are oppositely arranged in an intersecting way, the first bus bar is connected with a comb handle part of the first interdigital structure, the second bus bar is connected with a comb handle part of the second interdigital structure, each interdigital structure is respectively arranged between two adjacent electrode fingers of the other interdigital structure and is not contacted with each other, an interdigital area is formed between the tail end edge of the first interdigital structure and the tail end edge of the second interdigital structure, the ratio of the interdigital width of an interdigital electrode in the interdigital area to the width of an interdigital gap is 1:4-4:1, and the metallization ratio of the interdigital electrode in the interdigital area is 0.2-0.8.
The first interdigital structure and the second interdigital structure have the same structure and comprise a first interdigital electrode and a second interdigital electrode arranged on the first interdigital electrode, and the second interdigital electrode is used as a sacrificial layer. The first interdigital electrode isA single or multiple metal electrode layers, the material of the first type of interdigital electrode comprising at least one of Ti, al, cu, ag, ni, cr, pt, au, W, mo, the thickness of the first type of interdigital electrode being 3% -25% of the period length of the interdigital electrode of the interdigital transducer. The second type of interdigital electrode is a single-layer metal electrode layer, and the material of the second type of interdigital electrode is Ti, al, cu, cr, ni, W, au, pt, znO, al O3 or SiO 2 One of SiN, siOF, BSG, and the second type of interdigitated electrode has a thickness of 10% -150% of the thickness of the first type of interdigitated electrode, unlike the surface metal material of the first type of interdigitated electrode.
Specifically, as shown in fig. 1, 2 and 6 (b), the period length λ of the interdigital electrode of the interdigital transducer is set to 1.85-2.15um, and the metallization ratio of the interdigital electrode in the interdigital region is 0.46. The first interdigital structure comprises a first interdigital electrode I2 and a first interdigital electrode II 7, the second interdigital structure comprises a second interdigital electrode I3 and a second interdigital electrode II 8, wherein the first interdigital electrode I2 and the second interdigital electrode I3 serve as first interdigital electrodes, a multi-layer metal structure is formed by using Cr/Ag/Cu/Cr as materials, and the total thickness is set to be 7% of the period length lambda of the interdigital electrodes of the interdigital transducer. The first interdigital electrode II 7 and the second interdigital electrode II 8 are used as second interdigital electrodes, namely sacrificial layers, pure Al metal is used as a material, and the thickness is set to be 70% of the thickness of the first electrode layer.
The thickness of the rest first temperature compensation dielectric films is not lower than that of the first type of interdigital electrodes except for the first temperature compensation dielectric films above the interdigital electrodes, and the ratio of the thickness of the first temperature compensation dielectric films to the thickness of the first type of interdigital electrodes is in the range of 1:1-3:1. Specifically, the film thickness of the first temperature compensating dielectric film 9 at the gaps between adjacent electrode fingers is set to 15% of the period length lambda of the interdigital electrodes of the interdigital transducer, and the film thickness is greater than 7% of the thickness of the first interdigital electrode, and the height difference (i.e. the flatness of the dielectric) from the highest position to the lowest position of the surface of the first temperature compensating dielectric film in the gaps between adjacent electrode fingers is 15% of the thickness of the first interdigital electrode.
And 4, introducing SF6 or CF4 etching gas by using ICP etching equipment, and performing dry etching on the first temperature compensation dielectric film 9, wherein as shown in fig. 6 (d), the thickness of the rest first temperature compensation dielectric films 9 is reduced to 7% of the period length lambda of the interdigital electrodes of the interdigital transducer except for the first temperature compensation dielectric film 9 above the interdigital electrodes, so as to form a first temperature compensation dielectric layer 6a, and the ratio of the thickness of the first temperature compensation dielectric layer 6a to the thickness of the first interdigital electrodes 2 and 3 is 1:1. The SF6 or CF4 etching gas cannot corrode the metal Al of the second type of interdigital electrodes 7, 8, and eventually the first temperature compensating dielectric layer 6a forms a flat surface in the adjacent electrode finger gap and is level with the first type of interdigital electrodes 2, 3 of the interdigital transducer.
And 5, corroding the pure Al metal layers of the second type interdigital electrodes 7 and 8 (namely, the sacrificial layers) by using aluminum corrosive liquid, and simultaneously stripping the sacrificial layers and the first temperature compensation medium film 9 above the sacrificial layers, as shown in fig. 6 (e), so that a flat surface morphology is formed between the first type interdigital electrodes 2 and 3 and the first temperature compensation medium layer 6 a. The main components of the aluminum corrosive liquid are nitric acid, phosphoric acid and acetic acid, which can rapidly corrode pure Al, but does not corrode BSG material of the first temperature compensation dielectric layer 6a and Cr metal at the tops of the first type interdigital electrodes 7 and 8.
Alternatively, the method for preparing the temperature compensation dielectric layer in the step 3 and the step 6 is one of PECVD, HDPCVD, PVD, SOG, and may be selected according to practical situations.
The results of performance test of the surface acoustic wave filter prepared by the method of this example 1 are shown in fig. 7. The abscissa represents frequency, the ordinate represents insertion loss of the device, the center frequency is 1726M, the minimum insertion loss is within-1.0 dB, the in-band fluctuation is small, the passband is flat, the frequency temperature coefficient test result is-22 ppm/DEGC, and LiNbO 3 The temperature coefficient of the frequency of the conventional SAW device prepared on the crystal is-84 ppm/DEG C, so that the surface acoustic wave filter prepared by the surface acoustic wave transducer with the temperature compensation function has greatly improved temperature coefficient of the frequency and excellent performance.
Example 2:
the preparation method for preparing the acoustic surface wave transducer with the temperature compensation function comprises the following steps:
And 2, preparing the interdigital transducer on the piezoelectric substrate 1 through photoetching, evaporation, stripping and other processes.
The structure of the interdigital transducer is the same as that of embodiment 1, and a detailed description thereof will be omitted. Specifically, as shown in fig. 3, 4, and 6 (b), the period length λ of the interdigital electrode of the interdigital transducer is set to 3.8 to 4.2um, and the metallization ratio of the interdigital electrode in the interdigital region is 0.52. The first interdigital structure comprises a first interdigital electrode I2 and a first interdigital electrode II 7, the second interdigital structure comprises a second interdigital electrode I3 and a second interdigital electrode II 8, wherein the first interdigital electrode I2 and the second interdigital electrode I3 serve as first interdigital electrodes, the material forms a multi-layer metal structure by using Ti/Ag/Cu/Ti, and the total thickness is set to be 5% of the period length lambda of the interdigital electrodes of the interdigital transducer. The first interdigital electrode II 7 and the second interdigital electrode II 8 are used as second interdigital electrodes, namely sacrificial layers, pure Cr metal is used as a material, and the thickness is set to be 100% of the thickness of the first electrode layer.
And 3, preparing a first temperature compensation dielectric film 9 on the piezoelectric substrate 1 in a HDPCVD deposition mode, wherein the material is SiOF, the coverage area of the first temperature compensation dielectric film 9 just comprises the whole interdigital area, and the profile of the first temperature compensation dielectric film 9 in the interdigital area has the characteristics that the upper parts of interdigital electrodes are raised and the upper parts of adjacent electrode finger gaps are relatively flat.
The thickness of the rest first temperature compensation dielectric films is not lower than that of the first type of interdigital electrodes except for the first temperature compensation dielectric films above the interdigital electrodes, and the ratio of the thickness of the first temperature compensation dielectric films to the thickness of the first type of interdigital electrodes is in the range of 1:1-3:1. Specifically, the film thickness of the first temperature compensating dielectric film 9 at the gaps between adjacent electrode fingers is set to 12% of the period length lambda of the interdigital electrodes of the interdigital transducer, and the film thickness is greater than 5% of the thickness of the first interdigital electrode, and the height difference (i.e. the flatness of the dielectric) from the highest position to the lowest position of the surface of the first temperature compensating dielectric film in the gaps between adjacent electrode fingers is 10% of the thickness of the first interdigital electrode.
And 4, introducing SF6 or CF4 etching gas by using ICP etching equipment, and performing dry etching on the first temperature compensation dielectric film 9, wherein the thickness of the rest first temperature compensation dielectric films 9 except the first temperature compensation dielectric film 9 above the interdigital electrodes is reduced to 7% of the period length lambda of the interdigital electrodes of the interdigital transducer, so that a first temperature compensation dielectric layer 6a is formed, and the ratio of the thickness of the first temperature compensation dielectric layer 6a to the thickness of the first interdigital electrodes 2 and 3 is 1.4:1. The SF6 or CF4 etching gas cannot corrode the metal Cr of the second type of interdigital electrodes 7, 8, and eventually the first temperature compensating dielectric layer 6a forms a flat surface in the gaps between adjacent electrode fingers, and the height is slightly higher than the first type of interdigital electrodes 2, 3 of the interdigital transducer.
And 5, corroding the pure Cr metal layers of the second type interdigital electrodes 7 and 8 (namely sacrificial layers) by using chromium corrosive liquid, and simultaneously stripping the sacrificial layers and the first temperature compensation dielectric film 9 above the sacrificial layers, so that a surface morphology with high and low staggering is formed between the first type interdigital electrodes 2 and 3 and the first temperature compensation dielectric layer 6 a. The chromium etching solution used is capable of rapidly etching pure Cr but not the SiOF material of the first temperature compensating dielectric layer 6a and the Ti metal on top of the first type of inter-digital electrodes 7, 8.
And 6, preparing a second temperature compensation medium layer 6b on the surfaces of the first type of interdigital electrodes 2 and 3 and the first temperature compensation medium layer 6a in a PVD sputtering mode, wherein the material is SiON, the thickness of the SiON is 28% of the period length lambda of the interdigital electrode of the interdigital transducer, and the coverage area of the second temperature compensation medium layer 6b just comprises the whole interdigital area.
What has been described above is only a preferred embodiment of the present application, and the present invention is not limited to the above examples. It is to be understood that other modifications and variations which may be directly derived or contemplated by those skilled in the art without departing from the spirit and concepts of the present invention are deemed to be included within the scope of the present invention.
Claims (10)
1. A method for manufacturing a surface acoustic wave transducer with a temperature compensation function, the method comprising the steps of:
step 1, obtaining a piezoelectric substrate and cleaning the surface;
step 2, preparing an interdigital transducer on the piezoelectric substrate;
the interdigital transducer comprises a first interdigital structure, a second interdigital structure, a first bus bar and a second bus bar, wherein the first interdigital structure and the second interdigital structure are oppositely arranged in a crossing way, the first bus bar is connected with a comb handle part of the first interdigital structure, the second bus bar is connected with a comb handle part of the second interdigital structure, each interdigital structure is respectively arranged between two adjacent electrode fingers of the other interdigital structure and is not contacted with each other, and an interdigital area is formed between the tail end edge of the first interdigital structure and the tail end edge of the second interdigital structure;
the first interdigital structure and the second interdigital structure have the same structure and comprise a first interdigital electrode and a second interdigital electrode which is arranged on the first interdigital electrode and serves as a sacrificial layer;
step 3, preparing a first temperature compensation dielectric film on the piezoelectric substrate, wherein the coverage area of the first temperature compensation dielectric film at least comprises the whole interdigital area, and the cross section appearance of the first temperature compensation dielectric film in the interdigital area has the characteristics that the upper parts of interdigital electrodes are raised and the upper parts of adjacent electrode finger gaps are flat;
step 4, reducing the film thickness of the rest first temperature compensation dielectric films except for the first temperature compensation dielectric films above the interdigital electrodes to the vicinity of the thickness of the first interdigital electrodes by using a dry etching or wet etching method, so as to form a first temperature compensation dielectric layer; the dry etching gas or the wet etching liquid has etching selectivity, only etches the first temperature compensation dielectric film, and does not etch the sacrificial layer;
step 5, etching and stripping the sacrificial layer and the first temperature compensation dielectric film above the sacrificial layer by using a wet etching method, so that a flat or high-low staggered surface morphology is formed between the first interdigital electrode and the first temperature compensation dielectric layer, and the wet etching liquid has etching selectivity, rapidly etches the sacrificial layer and does not etch or extremely slowly etches the first temperature compensation dielectric layer;
and 6, preparing a second temperature compensation dielectric layer on the surfaces of the first type of interdigital electrodes and the first temperature compensation dielectric layer, wherein the coverage area of the second temperature compensation dielectric layer at least comprises the whole interdigital area.
2. The method of claim 1, wherein the first type of interdigitated electrode is a single or multiple metal electrode layers.
3. The method of claim 1, wherein the second type of interdigitated electrode is a single metal electrode layer.
4. A method according to any of claims 1-3, wherein the ratio of the width of the interdigitated electrodes to the width of the interdigitated gaps in the interdigitated regions is 1:4-4:1 and the ratio of metallization of the interdigitated electrodes in the interdigitated regions is 0.2-0.8.
5. The method of claim 1 or 2, wherein the material of the first type of interdigitated electrodes comprises at least one of Ti, al, cu, ag, ni, cr, pt, au, W, mo, and the thickness of the first type of interdigitated electrodes is 3% -25% of the period length of the interdigitated electrodes of the interdigital transducer.
6. A method according to claim 1 or 3, wherein the material of the second type of interdigitated electrode is Ti, al, cu, cr, ni, W, au, pt, znO, al O3, siO 2 One of SiN, siOF, BSG, and the second type of interdigitated electrode has a thickness of 10% -150% of the thickness of the first type of interdigitated electrode, and is different from the surface metal material of the first type of interdigitated electrode.
7. The method of claim 1, wherein the material of the first temperature compensating dielectric film in step 3 comprises SiO 2 、BSG、SiOF、SiON、Si 3 N 4 、TeO 2 Except for the first temperature compensation dielectric film above the interdigital electrodes, the thickness of the rest first temperature compensation dielectric films is not lower than that of the first interdigital electrodes, and the height difference from the highest position to the lowest position of the surfaces of the first temperature compensation dielectric films in the adjacent electrode finger gaps is less than 25% of the thickness of the first interdigital electrodes.
8. The method of claim 1, wherein the thickness of the first temperature compensating dielectric layer in step 5 is 3% -15% of the period length of the interdigital electrodes of the interdigital transducer, and the ratio of the thickness of the first temperature compensating dielectric layer to the thickness of the first interdigital electrodes is 1:3-2:1.
9. The method of claim 1, wherein the material of the second temperature compensating dielectric layer comprises SiO 2 、BSG、SiOF、SiON、Si 3 N 4 、TeO 2 At least one of the second temperature compensation dielectric layer is an interdigital electrode of the interdigital transducerFrom 10% to 40% of the cycle length of (a).
10. The method of claim 1, wherein the material of the piezoelectric substrate is a bulk or thin film of quartz, lithium niobate, lithium tantalate, aluminum nitride, or zinc oxide.
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| CN115133901A (en) * | 2022-06-30 | 2022-09-30 | 开元通信技术（厦门）有限公司 | Acoustic wave device structure having temperature compensation characteristic, filter, and electronic apparatus |
| CN115296642B (en) * | 2022-10-08 | 2023-03-24 | 深圳新声半导体有限公司 | Surface acoustic wave resonator structure, forming method thereof and filter |
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| CN116366022A (en) * | 2023-03-20 | 2023-06-30 | 江苏卓胜微电子股份有限公司 | Temperature compensated acoustic surface transducer and method of manufacture |
| CN116208119B (en) * | 2023-04-19 | 2023-07-14 | 深圳新声半导体有限公司 | Surface acoustic wave device and method for manufacturing the same |
| CN116979926B (en) * | 2023-09-01 | 2023-12-22 | 深圳新声半导体有限公司 | Surface acoustic wave resonator device, method of manufacturing the same, and filter |
| CN117318646A (en) * | 2023-10-12 | 2023-12-29 | 中微龙图电子科技无锡有限责任公司 | Manufacturing method of surface acoustic wave filter with temperature compensation function |
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