CN114759894A - Preparation method of high-performance high-frequency surface acoustic wave device based on electron beam exposure - Google Patents
Preparation method of high-performance high-frequency surface acoustic wave device based on electron beam exposure Download PDFInfo
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Abstract
The invention provides a preparation method of a high-performance high-frequency surface acoustic wave device based on electron beam exposure, which is characterized in that surface tackifying treatment is carried out on an insulating composite substrate, so that a glue type structure can be prevented from moving or falling off, and the uniformity of uniform glue can be improved; a double-layer glue system is selected, and the preparation of the inverted trapezoidal structure is realized by regulating and controlling the exposure dose, so that the glue removal and stripping are facilitated, the stripping yield is improved, and the glue residue formed by the fracture of the film can be reduced; the conductive layer is formed on the surface of the double-layer glue structure, so that charge accumulation of electron beams in the exposure process can be effectively dredged, electron beam positioning errors and surface spark discharge caused by formation of a micro electric field are avoided, and the transfer process of a designed pattern can be effectively transferred to the glue body; in the developing and stripping processes, only the double-layer glue needs to be developed and removed once, so that the production efficiency is higher. The method has the advantages of simple and easy-to-use process, high yield, good repeatability and high yield, and is suitable for batch preparation.
Description
Technical Field
The invention belongs to the technical field of microelectronic devices, and relates to a preparation method of a high-performance high-frequency surface acoustic wave device based on electron beam exposure.
Background
The Surface Acoustic Wave (SAW) device is a micro-nano functional device prepared on a piezoelectric material, the core unit structure is an interdigital transducer (also called an interdigital electrode), the interdigital transducer is composed of a group of periodically arranged positive and negative electrode metal films, and the interdigital transducer is used for converting an applied sine alternating current signal into an Acoustic Surface Wave vibration signal with the same frequency, otherwise, the Acoustic Surface Wave signal transmitted on the solid Surface can also be converted into an electric signal through the interdigital transducer.
The surface acoustic wave is mainly transmitted in a wavelength range of a solid surface, has high energy density, and has obvious change in the transmission rate under the perturbation of the external environment, so that the surface acoustic wave is widely applied to pressure, temperature, humidity and biochip sensors. In addition, the SAW device has very strong frequency selectivity, is often applied to the band-pass filtering and signal processing process of radio frequency signals, and has greater application requirements in the fields of 5G communication and the Internet of things.
The core indexes of the performance of the SAW device are working frequency, quality factor (Q) and insertion loss, wherein the quality factor and the insertion loss are related to the working frequency of the device, generally, the higher the working frequency is, the larger the insertion loss of the device is, and the working frequency and the quality factor of the SAW device are determined by the factors such as the material used for preparing the device, the surface acoustic wave speed and the period length of an interdigital electrode. In order to increase the operating frequency of SAW devices without affecting the quality factor level, on the one hand, consideration needs to be given to material system selection, and on the other hand, optimization of device manufacturing processes or introduction of new processes is needed.
The existing preparation method of the SAW device is difficult to meet the requirement of preparing a high-performance high-frequency SAW device, so that the development of a set of preparation method of the high-performance high-frequency SAW device based on electron beam exposure is really necessary.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a method for manufacturing a high-performance high-frequency surface acoustic wave device based on electron beam exposure, which is used for solving the problem that the high-performance high-frequency surface acoustic wave device is difficult to manufacture in the prior art.
In order to achieve the above objects and other related objects, the present invention provides a method for manufacturing a high-performance high-frequency surface acoustic wave device based on electron beam exposure, comprising the steps of:
providing an insulating composite base, wherein the insulating composite base comprises a supporting substrate and a piezoelectric film positioned on the supporting substrate;
carrying out surface tackifying treatment on the insulating composite substrate;
forming an electron beam resist composite layer on the insulating composite substrate, the electron beam resist composite layer including a first electron beam resist layer and a second electron beam resist layer on the first electron beam resist layer;
forming a conductive layer on the upper surface of the electron beam corrosion-resistant composite layer;
Performing electron beam exposure to form first trenches in the first electron beam resist layer and second trenches in the second electron beam resist layer, the first trenches and the second trenches communicating with each other and the first trenches having a width larger than that of the second trenches, so as to pattern the electron beam resist composite layer;
depositing a metal layer;
and removing the electron beam corrosion-resistant composite layer by adopting a stripping process, and forming an interdigital electrode on the insulating composite substrate.
Optionally, the support substrate comprises one of a silicon substrate, a silicon carbide substrate, a diamond substrate, and a sapphire substrate; the piezoelectric film comprises one of lithium niobate, potassium niobate, lithium tantalate, zinc oxide, quartz and aluminum nitride.
Optionally, the step of subjecting the insulating composite substrate to a surface adhesion promotion treatment comprises subjecting the insulating composite substrate to the surface adhesion promotion treatment with a Surpass4000 adhesion promoter to increase the surface adhesion of the electron beam resist composite layer to the insulating composite substrate.
Optionally, the exposure center dose of the first electron beam resist layer is larger than the exposure center dose of the second electron beam resist layer.
Optionally, the first e-beam resist layer comprises ZEP520A e-beam resist layer and the second e-beam resist layer comprises ARP6200 e-beam resist layer.
Alternatively, development with o-xylene and sol stripping with NMP solvent are included.
Optionally, the first and second electron beam resist layers are subjected to the electron beam exposure and the lift-off process simultaneously.
Optionally, the conductive layer formed on the upper surface of the electron beam resist composite layer is a water-soluble conductive layer.
Optionally, the performing of the electron beam exposure comprises:
designing a target graph by using layout design software to obtain a layout;
and correcting the layout by using the proximity effect parameters, and converting the layout into an electron beam exposure target file format so as to perform data conversion on the layout.
Optionally, the interdigital electrode is formed to comprise an Al interdigital electrode, wherein the interdigital line width comprises 150-500 nm.
As described above, according to the method for manufacturing a high-performance high-frequency surface acoustic wave device based on electron beam exposure, the surface tackifying treatment is performed on the insulating composite substrate to increase the adhesion between the electron beam anti-corrosion composite layer and the surface of the insulating composite substrate, prevent the glue type structure from moving or falling off, and improve the uniformity of glue homogenizing; the first electron beam resist layer and the second electron beam resist layer with high sensitivity are selected as a double-layer glue system, and an inverted trapezoidal structure is realized by regulating and controlling exposure dose, so that the photoresist removing and stripping can be facilitated, the stripping process difficulty is reduced, the stripping yield is improved, the colloid residue formed by film fracture can be reduced, and the edge roughness can be improved; the conductive layer is formed on the surface of the electron beam anti-corrosion composite layer with the double-layer glue structure, so that the charge accumulation formed on the surface of a sample by an electron beam in the exposure process can be effectively conducted, the charge can be conducted out of the sample through a probe on a sample clamp, a micro electric field is not formed after the charge accumulation, the phenomena of electron beam positioning error and surface spark discharge are avoided, and the transfer process of a designed pattern can be effectively transferred to a glue body; only the double-layer glue needs to be developed and removed once in the developing and stripping processes, and the production efficiency and the yield are higher.
The preparation method of the high-performance high-frequency surface acoustic wave device based on electron beam exposure has the advantages of simple and easy-to-use process, high productivity, good repeatability and high yield, and is suitable for preparing high-performance high-frequency SAW devices in batches.
Drawings
Fig. 1 is a flowchart illustrating a process for manufacturing a high-performance high-frequency SAW device based on electron beam exposure according to an embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a conductive layer formed in an embodiment of the invention.
FIG. 3 is a schematic view of a patterned electron beam resist composite layer according to an embodiment of the present invention.
Fig. 4 is a schematic structural diagram of a deposited metal layer in an embodiment of the invention.
FIG. 5 is a schematic diagram illustrating a SAW device formed after a lift-off process in accordance with an embodiment of the present invention.
Fig. 6 is an optical microscope photograph showing a SAW device in an embodiment of the present invention.
Fig. 7a and 7b are graphs showing S-parameter test results of the SAW device at very low temperatures according to the embodiment of the present invention.
Description of the element reference numerals
100 insulating composite substrate
200 first Electron Beam resist layer
201 first trench
300 second Electron Beam resist layer
301 second trench
400 conductive layer
500 metal layer
501 interdigital electrode
600 measurement lead
Detailed Description
The following embodiments of the present invention are provided by way of specific examples, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structure are not partially enlarged in general scale for convenience of illustration, and the schematic views are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "upper," and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Further, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.
In the context of this application, a structure described as a first feature being "on" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where additional features are formed in between the first and second features, such that the first and second features may not be in direct contact.
It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the drawings only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of each component in actual implementation may be changed freely, and the layout of the components may be more complicated.
Referring to fig. 1, the present embodiment provides a method for manufacturing a high-performance high-frequency surface acoustic wave device based on electron beam exposure, including the following steps:
s1: providing an insulating composite base, wherein the insulating composite base comprises a supporting substrate and a piezoelectric film positioned on the supporting substrate;
s2: performing surface tackifying treatment on the insulating composite substrate;
s3: forming an electron beam resist composite layer on the insulating composite substrate, the electron beam resist composite layer including a first electron beam resist layer and a second electron beam resist layer on the first electron beam resist layer;
S4: forming a conductive layer on the upper surface of the electron beam corrosion-resistant composite layer;
s5: performing electron beam exposure to form a first trench in the first electron beam resist layer and a second trench in the second electron beam resist layer, wherein the first trench and the second trench are communicated with each other and the width of the first trench is larger than that of the second trench, so as to pattern the electron beam resist composite layer;
s6: depositing a metal layer;
s7: and removing the electron beam corrosion-resistant composite layer by adopting a stripping process, and forming an interdigital electrode on the insulating composite substrate.
The method for manufacturing the SAW device will be further described with reference to fig. 2 to 6.
As shown in fig. 2, step S1 is performed to provide an insulating composite substrate 100, where the insulating composite substrate 100 includes a supporting substrate and a piezoelectric film on the supporting substrate.
As an example, the support substrate may include one of a silicon substrate, a silicon carbide substrate, a diamond substrate, and a sapphire substrate; the piezoelectric film may include one of lithium niobate, potassium niobate, lithium tantalate, zinc oxide, quartz, and aluminum nitride.
Specifically, the operating frequency and quality factor of the SAW device are determined by the material used for device fabrication, the surface acoustic wave velocity, the period length of the interdigital electrode, and other factors. Wherein, based on quartz and LiNbO 3SAW device operating frequency of ZnO and other materialsThe frequency of the weak signal sensing and the high-frequency requirements of 4.4-5 GHz for 5G communication cannot be met when the frequency is lower than 3 GHz. In order to increase the operating frequency of SAW devices without affecting the quality factor level, on the one hand, consideration needs to be given to material system selection, and on the other hand, optimization of device manufacturing processes or introduction of new processes is needed.
For material system selection, the piezoelectric material needs to be a material with high sound velocity and large electromechanical coupling coefficient; for the material of the supporting substrate, a material with low high-frequency loss is preferable to avoid influencing the quality factor of the device, and a material with high thermal conductivity is preferable to avoid influencing the power of the device. LiNbO with relative sound velocity lower than 6000m/s3The ZnO piezoelectric thin film material has a natural maximum sound velocity of 18000m/s, but since it does not have piezoelectric properties, it is preferable to use a multilayer film structure in which a piezoelectric thin film is combined with a diamond substrate/thin film. When the diamond single crystal supporting substrate is adopted, the diamond single crystal has limited size, is difficult to utilize advanced microelectronic integrated manufacturing process, has the defects of high cost, difficulty in batch manufacturing and the like, and has the defects of complicated device process steps, high difficulty in multilayer film quality control technology and the like. AlN is a piezoelectric material with the fastest sound velocity, the sound velocity can reach about 11000m/s, the transmission loss is low, the thermal stability and the chemical stability are excellent, and the AlN can be used for piezoelectric films of SAW devices with high frequency of more than 5 GHz. In this embodiment, the specific material system of the insulating composite substrate 100 in the SAW device is preferably AlN/Diamond, AlN/Saphire sapphire (Al) 2O3) Or AlN/Si, compared to the difficulty of providing a wafer-sized substrate with a diamond substrate, and the low quality of the thin film due to the large difference between the thermal expansion coefficients of the Si substrate and AlN, Sapphire single crystal not only has low high-frequency loss and high thermal conductivity, but also can provide a high-quality wafer-sized support substrate, which is beneficial for growing a uniform, flat and low-defect AlN piezoelectric thin film, and is suitable for batch manufacturing in microelectronic integrated manufacturing processes, and therefore, AlN/Sapphire is used as the insulating composite substrate 100 for manufacturing the high-frequency SAW device in this embodiment.
Next, step S2 is performed to perform surface adhesion treatment on the insulating composite substrate 100.
Specifically, the current main factor affecting the yield of the SAW device is the degumming problem occurring in the development stage, and for a substrate with a clean surface, the adhesion degree of the electronic resist prepared subsequently on the substrate is directly affected by the states of surface polarity, surface adsorption and the like, for example, a surface oxidation layer and surface adsorbed water molecules easily cause the electronic resist to be adhered poorly, so that the bottom of the resist is penetrated by a liquid developer in the development process, and colloids with periodic dense structures move or fall off during development. Therefore, how to enhance the adhesion of the selected electronic resist on the insulating substrate is very important to the yield of the SAW device.
In this embodiment, before forming the electron beam resist composite layer, it is preferable that the insulating composite substrate 100 is cleaned, and then a tackifier is coated on the insulating composite substrate 100 to perform surface adhesion treatment, and then the electron beam resist composite layer is formed. The Surpass4000 tackifier can be selected, specifically, the Surpass4000 tackifier is spin-coated on the surface of the insulating composite substrate 100, so that the Surpass4000 tackifier is adopted for surface tackifying treatment, adhesion between the electron beam corrosion-resistant composite layer formed subsequently and the surface of the insulating composite substrate 100 is increased, the Surpass4000 tackifier does not need to be removed manually, and can be naturally volatilized in a baking process, so that the influence on the formation of the metal layer 500 can be avoided.
Next, step S3 is performed to form an electron beam resist composite layer on the insulating composite substrate 100, wherein the electron beam resist composite layer includes a first electron beam resist layer 200 and a second electron beam resist layer 300 on the first electron beam resist layer 200.
Specifically, after a material system of the SAW device is determined, a device preparation process is the key for ensuring the final quality factor of the SAW device, and a good process not only meets the layout design index, but also reduces the damage of a processing process to the material performance. Wherein, the SAW device can be prepared by ultraviolet exposure, laser direct writing, electron beam exposure, deep ultraviolet/extreme ultraviolet exposure and other photoetching means And (3) constructing a micro-nano pattern mask, and then completing mask pattern transfer by means of etching, such as ion beam etching, reactive ion etching, plasma etching and the like or stripping and the like, so as to form a required device structure. Wherein, because the interdigital electrode of the SAW device is made of Al metal material commonly, if the pattern transfer is carried out by adopting an etching mode after photoetching, the used Cl2And BCl3On one hand, the mixed etching gas is hazardous and toxic gas, and has high requirements on safety and environmental protection, and on the other hand, the etching cost is far higher than that of stripping. Therefore, in this embodiment, the manufacturing process of the SAW device preferably adopts a lift-off manner to transfer the pattern structure. Further, when the operating frequency of the SAW device is increased to above 5GHz, the minimum feature size of the device needs to be reduced to submicron/deep submicron scale, such as in the range of 150-500 nm. With the smaller and smaller feature size, the requirements on defect control of device failure caused by size deviation and interdigital fracture, and process stability influencing device performance consistency and yield are higher and higher. Therefore, there is a need to select a lithography technique with a corresponding line width resolution capability based on the minimum feature size. Because electron beam exposure is used as a maskless lithography technology, the method has a good process application effect in the range from submicron to deep submicron characteristic dimension, and has the advantages of high resolution, high positioning accuracy, good exposure uniformity and the like.
For the preparation of a high-frequency SAW device based on an electron beam exposure process, how to overcome the influence of proximity effect in the exposure of an interdigital dense pattern with deep submicron line width, for example, the interdigital line width is in the range of 150-500 nm and the high-frequency SAW device is densely and periodically arranged, the thickness of a required electron beam resist needs to be hundreds of nanometers thick, so that the exposure dosage requirement is very large, for a dense periodic structure, the proximity effect during exposure is obvious, particularly the influence on an insulating substrate is more serious, and the distortion of an exposure pattern is easily caused; how to ensure the integrity of the periodic dense pattern structure during stripping, namely the stripping process is actually determined by controlling the glue type by electron beam exposure, especially for thick glue, on one hand, the periodic dense structure is easy to adhere and collapse the mask pattern during development, and on the other hand, the pattern edge is easy to be rough and even the structure is easy to be damaged during the transfer of the deep submicron patterns during stripping. If a single-layer electron beam resist such as 950PMMA is adopted for electron beam exposure, although periodic dense patterns can be completely transferred to the metal Al film layer, the interdigital structure is easily damaged during photoresist stripping, such as interdigital breakage, and the quality factor of a device is influenced; when a double-layer electron beam resist such as ZEP520A/MMA-EL11 is used for electron beam exposure, the inverse trapezoidal resist pattern is difficult to form due to the large difference of the required exposure doses of the two types of resist. Therefore, how to construct an inverted trapezoidal glue structure beneficial to subsequent stripping in an electron beam exposure stage is a key for ensuring the preparation yield and performance of the high-frequency SAW device.
In this embodiment, electron beam resist layers with different exposure center doses are sequentially spin-coated on the insulating composite substrate 100 to form an electron beam double resist layer, and the exposure center dose of the first electron beam resist layer 200 is greater than the exposure center dose of the second electron beam resist layer 300, for example, preferably, the first electron beam resist layer 200 is a ZEP520A electron beam resist layer, and the second electron beam resist layer 300 is an ARP6200 electron beam resist layer, so that only double-layer resist needs to be developed, single resist stripping is performed, higher efficiency and yield are achieved, and the electron beam exposure time can be greatly shortened; meanwhile, the inverse trapezoid glue type structure can be realized by utilizing the difference of the exposure center doses of the two resists, the difficulty of the stripping process is reduced, the stripping yield is improved, and the method has the advantages of simple flow and good repeatability.
Next, step S4 is performed to form a conductive layer 400 on the top surface of the electron beam resist composite layer.
For the preparation of the high-frequency SAW device based on the electron beam exposure process, the influence of charge accumulation on the insulating composite substrate 100 on the micro-nano pattern needs to be overcome, for example, the AlN/Sapphire insulating composite substrate and the AlN/Diamond insulating composite substrate are all insulating materials, electrons cannot be guided away in time when electron beam exposure is performed, charges are gathered on the surface of a sample to generate an electric field, so that the electron beam is deflected, and finally, the exposure pattern is deflected or distorted and deformed.
In this embodiment, the conductive layer 400 is directly formed on the upper surface of the electron beam anti-corrosion composite layer by a coating method, wherein the conductive layer 400 is preferably a water-soluble conductive layer, such as Discharge conductive adhesive, so that during subsequent electron beam exposure, charge accumulation formed on the surface of a sample by an electron beam during exposure can be effectively conducted through the conductive layer 400, and charges are conducted to the outside of the sample through a probe on a sample clamp, so as to avoid a micro electric field formed after the charge accumulation, avoid the phenomena of electron beam positioning error and surface spark Discharge, and ensure that a transfer process of a design pattern can be effectively transferred to a colloid. When the water-soluble conductive layer is used, the water-soluble conductive layer has the advantages that the water-soluble conductive layer is convenient to coat and can be removed in a subsequent developing process, and compared with other metal conductive layers, the water-soluble conductive layer has small influence on the penetrability of electron beams.
Next, as shown in fig. 3, step S5 is performed to perform electron beam exposure, thereby forming first trenches 201 in the first electron beam resist layer 200 and forming second trenches 301 in the second electron beam resist layer 300, wherein the first trenches 201 and the second trenches 301 penetrate each other, and the first trenches 201 have a larger width than the second trenches 301, so as to pattern the electron beam resist composite layer.
As an example, the electron beam exposure is performed by the following steps:
designing a target graph by using layout design software to obtain a layout;
and correcting the layout by using the proximity effect parameters, and converting the layout into an electron beam exposure target file format so as to perform data conversion on the layout.
Specifically, L-edit software can be adopted to adapt parameters such as line width, effective area and duty ratio structure according to different requirements, target patterns of relevant grating structures and interdigital electrodes in a core area are designed, the layout design is corrected by using proximity effect parameters, and the target patterns are converted into an electron beam exposure target file format, so that exposure can be carried out through an electron beam system, and the designed patterns can be transferred to the electron beam anti-corrosion composite layer.
Since the exposure center dose of the first electron beam resist layer 200 is greater than the exposure center dose of the second electron beam resist layer 300, the preparation of the trench having the inverted trapezoid structure can be realized by utilizing the difference of the exposure center doses of the first electron beam resist layer 200 and the second electron beam resist layer 300, that is, the first trench 201 having a larger width and the second trench 301 having a smaller width are formed to be communicated with each other, so that the difficulty of the subsequent stripping process can be reduced, and the stripping yield can be improved.
In this embodiment, the substrate coated with the final conductive paste is placed in an electron beam exposure apparatus for exposure, and after exposure, the substrate is taken out and developed to form an inverted trapezoidal paste structure as shown in fig. 3, wherein the first electron beam resist layer 201 is a ZEP520A electron beam resist layer, and the second electron beam resist layer 301 is an ARP6200 electron beam resist layer, so that the two resists can be developed in an ARP546 solution and ortho-xylene, respectively.
Next, as shown in fig. 4, step S6 is performed to deposit the metal layer 500.
The metal layer 500 may include an Al metal layer, and after a predetermined vacuum degree is reached, an Al film may be grown to form the metal layer 500, so that the interdigital electrode 501 made of Al may be prepared after a subsequent stripping process is completed, as shown in fig. 5.
Next, as shown in fig. 5, step S7 is performed to remove the electron beam resist composite layer by a lift-off process, so as to form the interdigital electrode 501 on the insulating composite substrate 100.
Specifically, the grown sample can be placed in an N-methylpyrrolidone (NMP) solution, so that the excess colloid can be removed after single photoresist removal, thereby improving the production efficiency and yield, and completing the preparation of the high-performance high-frequency SAW device, as shown in fig. 6, a light mirror scanning diagram of the SAW device under a light mirror is illustrated. The core area is the interdigital electrode 501 part, and the whole device is connected to a corresponding test system through a measurement lead 600 by using a two-end method.
After the operating frequency of the SAW device is increased, the feature size of the pattern structure in the core region needs to be controlled between 100-1000nm, and the aspect ratio can reach 600:1 or more, for example, for 5G applications, the feature size of the SAW device needs to be controlled in the range of 150-500 nm. Therefore, in this embodiment, the interdigital line width of the formed interdigital electrode 501 may include 150 to 500nm, such as 150nm, 200nm, 300nm, 400nm, 500nm, and the like.
Fig. 7a and 7b are graphs illustrating S parameter test results of the SAW device at 10mK, and fig. 7a and 7b respectively show the magnitude and phase measurement results of the reflection coefficient S11 of the SAW single-port resonator at low temperature of 10 mK. As shown, the resonant frequency f of the SAW deviceo5.5848GHz, very close to the design value. From the relationship between the resonance frequency and the device wavelength, the surface acoustic wave velocity of AlN/sapphire can be estimated to be about 5600 m/s. Obtaining intrinsic quality factor Q of SAW resonant cavity by fitting according to formulaiAnd coupling quality factor Qe7014 and 76371 respectively, which shows that the SAW resonant cavity prepared by the process has lower loss, thereby showing excellent application prospect in the applications of low-temperature electronics and superconducting electronics. .
In summary, according to the method for manufacturing the high-performance high-frequency surface acoustic wave device based on electron beam exposure, the surface tackifying treatment is performed on the insulating composite substrate to increase the adhesion between the electron beam anti-corrosion composite layer and the surface of the insulating composite substrate, prevent the glue type structure from moving or falling off, and improve the uniformity of glue homogenizing; the first electron beam resist layer and the second electron beam resist layer with high sensitivity are selected as a double-layer glue system, and an inverted trapezoidal structure is realized by regulating and controlling exposure dose, so that the photoresist removing and stripping can be facilitated, the stripping process difficulty is reduced, the stripping yield is improved, the colloid residue formed by film fracture can be reduced, and the edge roughness can be improved; the conductive layer is formed on the surface of the electron beam anti-corrosion composite layer with the double-layer glue structure, so that the charge accumulation formed on the surface of a sample by an electron beam in the exposure process can be effectively conducted, the charge can be conducted out of the sample through a probe on a sample clamp, a micro electric field is not formed after the charge accumulation, the phenomena of electron beam positioning error and surface spark discharge are avoided, and the transfer process of a designed pattern can be effectively transferred to a glue body; only the double-layer glue needs to be developed and removed once in the developing and stripping processes, and the production efficiency and the yield are higher.
The preparation method of the high-performance high-frequency surface acoustic wave device based on electron beam exposure has the advantages of simple and easy-to-use process, high productivity, good repeatability and high yield, and is suitable for preparing high-performance high-frequency SAW devices in batches.
The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Those skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (10)
1. A preparation method of a high-performance high-frequency surface acoustic wave device based on electron beam exposure is characterized by comprising the following steps:
providing an insulating composite base, wherein the insulating composite base comprises a supporting substrate and a piezoelectric film positioned on the supporting substrate;
carrying out surface tackifying treatment on the insulating composite substrate;
forming an electron beam resist composite layer on the insulating composite substrate, the electron beam resist composite layer including a first electron beam resist layer and a second electron beam resist layer on the first electron beam resist layer;
Forming a conductive layer on the upper surface of the electron beam corrosion-resistant composite layer;
performing electron beam exposure to form a first trench in the first electron beam resist layer and a second trench in the second electron beam resist layer, the first trench and the second trench communicating with each other and the first trench having a width larger than the second trench, to pattern the electron beam resist composite layer;
depositing a metal layer;
and removing the electron beam corrosion-resistant composite layer by adopting a stripping process, and forming an interdigital electrode on the insulating composite substrate.
2. The method of claim 1, wherein: the support substrate comprises one of a silicon substrate, a silicon carbide substrate, a diamond substrate and a sapphire substrate; the piezoelectric film comprises one of lithium niobate, potassium niobate, lithium tantalate, zinc oxide, quartz and aluminum nitride.
3. The method of claim 1, wherein: the step of subjecting the insulating composite substrate to a surface adhesion promotion treatment includes subjecting the insulating composite substrate to the surface adhesion promotion treatment using a Surpass4000 adhesion promoter to increase the surface adhesion of the electron beam resist composite layer to the insulating composite substrate.
4. The method of claim 1, wherein: the exposure center dose of the first electron beam resist layer is larger than the exposure center dose of the second electron beam resist layer.
5. The production method according to claim 1, characterized in that: the first electron beam resist layer comprises ZEP520A electron beam resist layer, and the second electron beam resist layer comprises ARP6200 electron beam resist layer.
6. The production method according to claim 5, characterized in that: including development with o-xylene and sol stripping with NMP solvent.
7. The method of claim 1, wherein: the first electron beam resist layer and the second electron beam resist layer are subjected to the electron beam exposure and the lift-off process simultaneously.
8. The method of claim 1, wherein: the conductive layer formed on the upper surface of the electron beam resist composite layer is a water-soluble conductive layer.
9. The method of claim 1, wherein: the electron beam exposure method comprises the following steps:
designing a target graph by using layout design software to obtain a layout;
and correcting the layout by using the proximity effect parameters, and converting the layout into an electron beam exposure target file format so as to perform data conversion on the layout.
10. The method of claim 1, wherein: the formed interdigital electrode comprises an Al interdigital electrode, wherein the interdigital line width comprises 150-500 nm.
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