CN114759894A - Preparation method of high-performance high-frequency surface acoustic wave device based on electron beam exposure - Google Patents

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

Preparation method of high-performance high-frequency surface acoustic wave device based on electron beam exposure

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 technique

A 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 known as an interdigital electrode). It is composed of metal films of positive and negative electrodes arranged in a linear manner. Its function is to convert the applied sinusoidal alternating current signal into a surface acoustic wave vibration signal of the same frequency. On the contrary, the surface acoustic wave signal transmitted on the solid surface can also be converted by an interdigital transducer. into an electrical signal.

SAW mainly propagates in a wavelength range on the solid surface and has a high energy density. Under the perturbation of the external environment, the propagation rate of the acoustic wave will change significantly, so it is widely used in pressure, temperature, humidity and biochip sensors. In addition, SAW devices have strong frequency selectivity and are often used in the bandpass filtering and signal processing of radio frequency signals, and have great application requirements in the fields of 5G communication and the Internet of Things.

The core indicators of SAW device performance are operating frequency, quality factor (Q) and insertion loss. Among them, the quality factor and insertion loss are related to the operating frequency of the device. Generally, the higher the operating frequency, the greater the insertion loss of the device, and the operating frequency of the SAW device. and quality factors are determined by factors such as the materials used for device fabrication, SAW velocity and interdigital electrode period length. In order to increase the operating frequency of SAW devices without affecting the quality factor level, on the one hand, it is necessary to consider the selection of material systems, and on the other hand, it is necessary to optimize the device fabrication process or introduce new processes.

The existing preparation methods of SAW devices are difficult to meet the needs of preparing high-performance high-frequency SAW devices. Therefore, it is necessary to develop a set of preparation methods for high-performance high-frequency SAW devices based on electron beam exposure.

SUMMARY OF THE INVENTION

In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a preparation method of a high-performance high-frequency surface acoustic wave device based on electron beam exposure, which is used to solve the problem that it is difficult to prepare a high-performance high-frequency surface acoustic wave device in the prior art .

To achieve the above purpose and other related purposes, the present invention provides a preparation method of a high-performance high-frequency surface acoustic wave device based on electron beam exposure, comprising the following steps:

An insulating composite substrate is provided, the insulating composite substrate includes a support substrate and a piezoelectric thin film on the support substrate;

performing 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 comprising a first electron beam resist layer and a second electron beam resist layer on the first electron beam resist layer Floor;

forming a conductive layer on the upper surface of the electron beam resist composite layer;

performing electron beam exposure, forming a first trench in the first electron beam resist layer and forming a second trench in the second electron beam resist layer, the first trench and the second trench connected to 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;

depositing a metal layer;

The electron beam resist composite layer is removed by a lift-off process, and interdigitated electrodes are formed on the insulating composite substrate.

Optionally, the supporting substrate includes one of a silicon substrate, a silicon carbide substrate, a diamond substrate and a sapphire substrate; the piezoelectric film includes lithium niobate, potassium niobate, lithium tantalate, oxide One of zinc, quartz and aluminum nitride.

Optionally, the step of performing the surface tackifying treatment on the insulating composite substrate includes using Surpass4000 tackifier to perform the surface tackifying treatment, so as to increase the surface tackiness of the electron beam resist composite layer and the insulating composite substrate. Attachment.

Optionally, the central exposure dose of the first electron beam resist layer is greater than the central exposure dose of the second electron beam resist layer.

Optionally, the first electron beam resist layer includes a ZEP520A electron beam resist layer, and the second electron beam resist layer includes an ARP6200 electron beam resist layer.

Optionally, development with ortho-xylene is included, and sol stripping with NMP solvent is included.

Optionally, 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 at the same time.

Optionally, the conductive layer formed on the upper surface of the electron beam resist composite layer is a water-soluble conductive layer.

Optionally, when performing the electron beam exposure, the following steps are included:

Use layout design software to design target graphics and obtain layout;

The layout is corrected using proximity effect parameters and converted into an electron beam exposure target file format to perform data conversion on the layout.

Optionally, the formed interdigital electrodes include Al interdigitated electrodes, wherein the interdigital line width includes 150-500 nm.

As mentioned above, in the preparation method of the high-performance high-frequency surface acoustic wave device based on electron beam exposure of the present invention, the surface tackifying treatment is performed on the insulating composite substrate to increase the adhesion between the electron beam resist composite layer and the surface of the insulating composite substrate. Adhesion to prevent the glue structure from moving or falling off, and at the same time, it can also improve the uniformity of the glue; the first electron beam resist layer and the second electron beam resist layer with high sensitivity are selected as the double-layer glue system, and the exposure dose is adjusted by adjusting the exposure dose. The realization of the inverted trapezoidal structure can not only facilitate debonding and peeling, reduce the difficulty of the peeling process, improve the peeling yield, but also reduce the colloid residue formed by the film breakage, thereby improving the edge roughness; A conductive layer is formed on the surface of the beam resist composite layer, which can effectively divert the charge accumulation formed on the surface of the sample by the electron beam during the exposure process, so that the electric charge can be diverted to the outside of the sample through the probe on the sample holder, so as to avoid the formation of charge accumulation. The micro electric field avoids the phenomenon of electron beam positioning error and surface spark discharge, and ensures that the transfer process of the design pattern can be effectively transferred to the colloid; during the development and peeling process, only the double-layer adhesive needs to be developed and removed in a single time. Has high production efficiency and yield.

The preparation method of the high-performance high-frequency surface acoustic wave device based on electron beam exposure of the present invention has the advantages of simple and easy-to-use process, high productivity, good repeatability and high yield, and is suitable for the preparation of batch high-performance high-frequency SAW devices.

Description of drawings

FIG. 1 is a flow chart of a fabrication process of a high-performance high-frequency SAW device based on electron beam exposure in an embodiment of the present invention.

FIG. 2 is a schematic diagram of a structure after forming a conductive layer in an embodiment of the present invention.

FIG. 3 is a schematic diagram showing the structure of a patterned electron beam resist composite layer in an embodiment of the present invention.

FIG. 4 is a schematic diagram of a structure after depositing a metal layer in an embodiment of the present invention.

FIG. 5 is a schematic structural diagram of a SAW device formed after a lift-off process in an embodiment of the present invention.

FIG. 6 shows an optical microscope image of the SAW device in the embodiment of the present invention.

FIG. 7 a and FIG. 7 b respectively show the S-parameter test results of the SAW device in the embodiment of the present invention at a very low temperature.

Component label description

100 Insulating Composite Substrates

200 first electron beam resist

201 First groove

300 second electron beam resist

301 Second groove

400 conductive layers

500 metal layers

501 Interdigital electrode

600 Measurement Leads

Detailed ways

The embodiments of the present invention are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

When describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional views showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the protection scope of the present invention. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in the actual production.

For convenience of description, spatially relative terms such as "below," "below," "below," "below," "above," "on," etc. may be used herein to describe an element shown in the figures or The relationship of a feature to other components or features. It will be understood that these spatially relative terms are intended to encompass other directions of the device in use or operation than those depicted in the figures. In addition, 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, descriptions of structures where a first feature is "on" a second feature can include embodiments in which the first and second features are formed in direct contact, and can also include further features formed over the first and second features. Embodiments between the second features such that the first and second features may not be in direct contact.

It should be noted that the diagrams provided in this embodiment are only to illustrate the basic concept of the present invention in a schematic way, so the diagrams only show the components related to the present invention rather than the number, shape and the number of components in the actual implementation. For dimension drawing, the type, quantity and proportion of each component can be arbitrarily changed in actual implementation, and the component layout may also be more complicated.

Referring to FIG. 1 , the present embodiment provides a preparation method of a high-performance high-frequency surface acoustic wave device based on electron beam exposure, including the following steps:

S1: Provide an insulating composite substrate, the insulating composite substrate includes a support substrate and a piezoelectric film on the support substrate;

S2: performing surface tackifying treatment on the insulating composite substrate;

S3: forming an electron beam resist composite layer on the insulating composite substrate, where the electron beam resist composite layer includes a first electron beam resist layer and a second electron beam resist layer on the first electron beam resist layer resist layer;

S4: forming a conductive layer on the upper surface of the electron beam resist composite layer;

S5: performing electron beam exposure, forming a first trench on the first electron beam resist layer and forming a second trench on the second electron beam resist layer, the first trench and the second trench The grooves are connected with each other and the width of the first groove is larger than that of the second groove, so as to pattern the electron beam resist composite layer;

S6: deposit a metal layer;

S7: The electron beam resist composite layer is removed by a lift-off process, and interdigital electrodes are formed on the insulating composite substrate.

The manufacturing method of the SAW device will be further introduced below with reference to FIGS. 2 to 6 .

As shown in FIG. 2 , step S1 is first performed to provide an insulating composite substrate 100 . The insulating composite substrate 100 includes a support substrate and a piezoelectric film on the support substrate.

As an example, the supporting substrate may include one of a silicon substrate, a silicon carbide substrate, a diamond substrate and a sapphire substrate; the piezoelectric film may include lithium niobate, potassium niobate, lithium tantalate, One of zinc oxide, quartz and aluminum nitride.

Specifically, the operating frequency and quality factor of the SAW device are determined by factors such as the materials used in the fabrication of the device, the velocity of the surface acoustic wave, and the period length of the interdigital electrodes. Among them, the operating frequencies of SAW devices based on materials such as quartz, LiNbO ₃ , and ZnO are all lower than 3 GHz, which cannot meet the high-frequency requirements of 4.4-5 GHz for weak signal sensing and 5G communication. In order to increase the operating frequency of SAW devices without affecting the quality factor level, on the one hand, it is necessary to consider the selection of material systems, and on the other hand, it is necessary to optimize the device fabrication process or introduce new processes.

Among them, for the selection of material system, piezoelectric materials need to choose materials with high sound velocity and large electromechanical coupling coefficient; for supporting substrate materials, materials with low high-frequency loss are preferred to avoid affecting the device quality factor, and thermal conductivity is preferred High material to avoid materials affecting device power. Compared with LiNbO ₃ and ZnO piezoelectric film materials whose sound speed is lower than 6000m/s, although diamond has the highest sound speed of 18000m/s in nature, it does not have piezoelectric properties, so it is preferable to combine piezoelectric film with diamond substrate/ The thin films are used in combination to form a multilayer film structure. When the diamond single crystal support substrate is used, the size of the diamond single crystal is limited, and it is difficult to use the advanced microelectronic integrated manufacturing process, and there are disadvantages such as high cost and unfavorable mass manufacturing. Disadvantages of high technical difficulty. AlN is the piezoelectric material with the fastest sound speed. The sound speed can reach about 11000m/s, and it has low transmission loss, excellent thermal stability and chemical stability. It can be used as a piezoelectric film for SAW devices at high frequencies above 5GHz. In this embodiment, the specific material system of the insulating composite substrate 100 in the SAW device is preferably AlN/Diamond diamond, AlN/Saphire sapphire (Al ₂ O ₃ ) or AlN/Si, and it is difficult to provide a crystal with a diamond substrate. Compared with the low-quality thin films due to the large difference in thermal expansion coefficients between round-sized substrates, Si substrates and AlN, Sapphire single crystal not only has low high-frequency loss and high thermal conductivity, but also can provide high-quality wafer-sized support substrates. It is beneficial to grow a uniform, flat and low-defect AlN piezoelectric thin film, and is suitable for mass production in a microelectronic integrated manufacturing process. Therefore, in this embodiment, AlN/Sapphire is used as the insulating composite substrate 100 for fabricating the high-frequency SAW device.

Next, step S2 is performed to perform surface tackifying treatment on the insulating composite substrate 100 .

Specifically, the main factor affecting the yield of SAW devices currently comes from the degumming problem in the development stage. For a substrate with a clean surface, the surface polarity, surface adsorption and other states will directly affect the subsequent preparation of the electronic resist on the substrate. The degree of adhesion on the surface, such as the surface oxide layer and the water molecules adsorbed on the surface, can easily lead to poor adhesion of the electronic resist, which will cause the bottom of the resist to be penetrated by the liquid developer during the development process. Densely structured colloids appear to move or fall off. Therefore, how to enhance the adhesion of selected electronic resists on insulating substrates is very important for the yield of SAW devices.

In this embodiment, before forming the electron beam resist composite layer, preferably, the insulating composite substrate 100 is cleaned first, and then a tackifier is coated on the insulating composite substrate 100 for surface tackifying treatment. Then, the electron beam resist composite layer is formed. Wherein, the tackifier can be selected from Surpass4000 tackifier. Specifically, the Surpass4000 tackifier can be used for the surface tackifying treatment by spin-coating the Surpass4000 tackifier on the surface of the insulating composite substrate 100. In order to increase the adhesion between the electron beam resist composite layer formed later and the surface of the insulating composite substrate 100, and the Surpass4000 tackifier does not need to be removed artificially, it can be naturally volatilized during the baking process, so as to avoid Subsequent effects on the formation of the metal layer 500 .

Next, step S3 is performed to form an electron beam resist composite layer on the insulating composite substrate 100 , and the electron beam resist composite layer includes a first electron beam resist layer 200 and an electron beam resist layer located on the first electron beam resist layer 200 . Second electron beam resist layer 300 on 200 .

Specifically, when the material system of the SAW device is determined, the device fabrication process is the key to ensuring the final quality factor of the SAW device. A good process must not only meet the layout design indicators, but also reduce the damage to the material properties during processing. Among them, the preparation of SAW devices can use photolithography methods such as ultraviolet exposure, laser direct writing, electron beam exposure, deep ultraviolet/extreme ultraviolet exposure to construct micro-nano pattern masks, and then use etching, such as ion beam etching, reaction The mask pattern transfer is completed by means of ion etching, plasma etching, etc., or stripping, to form the desired device structure. Among them, since the interdigitated electrodes of SAW devices are usually made of Al metal material, if the pattern transfer is performed by etching after photolithography, the mixed etching gas of Cl ₂ and BCl ₃ is used, which is a dangerous toxic gas on the one hand. The requirements for safety and environmental protection are high. On the other hand, the cost of etching is much higher than that of stripping. Therefore, in this embodiment, it is preferred that the preparation process of the SAW device adopts a lift-off method to transfer the pattern structure. Further, when the operating frequency of the SAW device is increased to above 5 GHz, the minimum feature size of the device needs to be reduced to the submicron/deep submicron scale, such as in the range of 150-500 nm. As the feature size gets smaller and smaller, the requirements for defect control that lead to device failure, such as dimensional deviation resulting in center frequency offset, interdigital breakage, and process stability that affect device performance consistency and yield, are getting higher and higher. Therefore, it is necessary to select a lithography technique with corresponding line width resolution capability according to the minimum feature size. Since electron beam exposure is a maskless lithography technology, it has good process application effects in the sub-micron to deep sub-micron feature size range, and has the advantages of high resolution, high positioning accuracy, and good exposure uniformity. Based on the above technology Features, in this embodiment, electron beam exposure is preferably used as a preparation process for preparing the SAW device with high performance and high frequency.

For the preparation of high-frequency SAW devices based on electron beam exposure, how to overcome the proximity effect in the exposure of interdigitated dense patterns with deep submicron linewidths, such as interdigitated linewidths in the range of 150-500nm and dense periodicity Arranged high-frequency SAW devices, the required thickness of the electron beam resist needs to be several hundred nanometers thick, so the exposure dose is required to be large. For dense periodic structures, the proximity effect during exposure is obvious, especially in insulating linings. The impact on the bottom is more serious, and it is easy to cause distortion of the exposure pattern; how to ensure the integrity of the periodic dense pattern structure during peeling, that is, the peeling process is actually determined by the control of the glue type by electron beam exposure, especially for thick glue On the one hand, the periodic dense structure is prone to bonding and collapse of the mask pattern during development, and on the other hand, these deep submicron patterns are prone to rough pattern edges and even structural damage during the transfer of these deep submicron patterns during the peeling process. If a single-layer electron beam resist, such as 950PMMA, is used for electron beam exposure, although the periodic dense pattern can be completely transferred to the metal Al film layer, it is very easy to damage the interdigital structure during debonding and peeling, such as interdigitated fingers. Fractures will affect the quality factor of the device; if a double-layer electron beam resist, such as ZEP520A/MMA-EL11, is used for electron beam exposure, it is difficult to form an inverted trapezoid type of glue due to the large difference in exposure dose between the two colloids. Therefore, how to construct an inverted trapezoidal glue-type structure in the electron beam exposure stage that is conducive to subsequent peeling is the key to the fabrication yield and performance assurance of high-frequency SAW devices.

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 first electron beam resist layer 200 is exposed to The central dose is greater than the exposure central dose of the second electron beam resist layer 300. For example, the first electron beam resist layer 200 is preferably a ZEP520A electron beam resist layer, and the second electron beam resist layer 300 is ARP6200. Electron beam resist layer, thus only need to develop double-layer glue, single-step glue removal, with high efficiency and productivity, can greatly shorten the electron beam exposure time; at the same time, use two kinds of resists to expose the central dose The gap can realize the inverted trapezoidal glue type structure, reduce the difficulty of the peeling process, improve the peeling yield, and has the advantages of simple process and good repeatability.

Next, step S4 is performed to form a conductive layer 400 on the upper surface of the electron beam resist composite layer.

For the preparation of high-frequency SAW devices based on the electron beam exposure process, it is necessary to overcome the influence of the charge accumulation on the insulating composite substrate 100 on the micro-nano patterns, such as the AlN/Sapphire insulating composite substrate, the AlN/Diamond insulating composite substrate The substrates are all insulating materials. During electron beam exposure, the electrons cannot be conducted away in time, and the charges will accumulate on the surface of the sample to generate an electric field, which will cause the electron beam to deflect, and eventually cause the exposure pattern to shift or distort.

In this embodiment, the conductive layer 400 is directly formed on the upper surface of the electron beam resist composite layer by a coating method, wherein the conductive layer 400 is preferably a water-soluble conductive layer, such as a Discharge conductive adhesive, so that the During subsequent electron beam exposure, the conductive layer 400 can effectively divert the charge accumulation formed by the electron beam on the surface of the sample during the exposure process, and the charge can be diverted to the outside of the sample through the probe on the sample holder, so as to avoid charge accumulation. A micro electric field is formed to avoid the phenomenon of electron beam positioning error and surface spark discharge, and to ensure that the transfer process of the design pattern can be effectively transferred to the colloid. Among them, when the water-soluble conductive layer is used, its advantages are mainly reflected in the convenience of coating, which can be removed in the subsequent development process, and has less influence on the penetration of electron beams compared with other metal conductive layers.

Next, as shown in FIG. 3 , step S5 is performed, electron beam exposure is performed, a first trench 201 is formed in the first electron beam resist layer 200 and a first trench 201 is formed in the second electron beam resist layer 300 Two trenches 301, the first trench 201 and the second trench 301 are connected to each other and the width of the first trench 201 is larger than that of the second trench 301, so as to pattern the electron beam resist composite layer .

As an example, when the electron beam exposure is performed, the following steps are included:

Use layout design software to design target graphics and obtain layout;

The layout is corrected using proximity effect parameters and converted into an electron beam exposure target file format to perform data conversion on the layout.

Specifically, L-edit software can be used to adapt parameters such as line width, effective area, and duty cycle structure according to different requirements, design the target pattern of the grating structure and interdigital electrodes in the core area, and use the proximity effect parameters to correct the layout. The design is converted into an electron beam exposure target file format so that exposure can be performed by an electron beam system to transfer the designed pattern onto the electron beam resist composite layer.

Wherein, 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 first electron beam resist layer 200 and the first electron beam resist layer 200 and the first electron beam resist layer 200 can be used. The difference between the exposure center doses of the two electron beam resist layers 300 realizes the preparation of a trench with an inverted trapezoidal structure, that is, the first trench 201 with a larger width and the second trench with a smaller width are formed. The trench 301 can reduce the difficulty of the subsequent peeling process and improve the peeling yield.

In this embodiment, the substrate coated with the final conductive adhesive is put into an electron beam exposure device for exposure, and after exposure is completed, the substrate is taken out and developed to form an inverted trapezoidal adhesive structure as shown in FIG. 3 , wherein , because the first electron beam resist layer 201 adopts the ZEP520A electron beam resist layer, and the second electron beam resist layer 301 adopts the ARP6200 electron beam resist layer, so that the two resists can be used in the ARP546 solution and adjacent to the developed separately in xylene.

Next, as shown in FIG. 4 , step S6 is performed to deposit a metal layer 500 .

Wherein, the metal layer 500 may include an Al metal layer, and after reaching a preset vacuum degree, an Al film can be grown to form the metal layer 500, so that after the subsequent peeling process is completed, the material can be prepared as Al The interdigital electrode 501 is shown in FIG. 5 .

Next, as shown in FIG. 5 , step S7 is performed, the electron beam resist composite layer is removed by a lift-off process, and interdigital electrodes 501 are formed on the insulating composite substrate 100 .

Specifically, the grown sample can be put into N-methylpyrrolidone (NMP) solution, so that the excess colloid can be removed after a single degumming, thereby improving production efficiency and yield, and achieving high performance and high performance The preparation of the SAW device at high frequency, as shown in FIG. 6 , the optical mirror scanning diagram of the SAW device under the optical microscope. The core area is the part of the interdigital electrode 501 , and the entire device is connected to the corresponding test system through the measurement lead 600 by the two-terminal method.

Among them, when the operating frequency of the SAW device is increased, the feature size of the pattern structure in the core area needs to be controlled between 100-1000nm, and the aspect ratio can reach 600:1 or above. For example, for 5G applications, the feature size of the SAW device should be controlled within 150-500nm range. Therefore, in this embodiment, the interdigital line width of the formed interdigital electrode 501 may include 150-500 nm, such as 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, and the like.

Figures 7a and 7b show the S-parameter test results of the SAW device at 10mK, and Figures 7a and 7b respectively show the S11 amplitude and phase measurement results of the SAW single-port resonator at a low temperature of 10mK. As shown in the figure, the resonant frequency f _o of the SAW device is 5.5848 GHz, which is very close to the design value. According to the relationship between the resonance frequency and the wavelength of the device, it can be estimated that the surface acoustic wave velocity of AlN/sapphire is about 5600 m/s. According to the formula fitting, the intrinsic quality factor Q _i and coupling quality factor Q _e of the SAW resonator are 7014 and 76371, respectively, which shows that the SAW resonator fabricated by this process has lower loss, which can be used in low-temperature electronics, It has shown excellent application prospects in the application of superconducting electronics. .

To sum up, in the preparation method of the high-performance high-frequency surface acoustic wave device based on electron beam exposure of the present invention, the surface tackifying treatment is performed on the insulating composite substrate to increase the adhesion between the electron beam resist composite layer and the surface of the insulating composite substrate. Adhesion to prevent the glue structure from moving or falling off, and at the same time, it can improve the uniformity of the glue; the first electron beam resist layer and the second electron beam resist layer with high sensitivity are selected as the double-layer glue system, and the exposure is adjusted by adjusting the exposure. The dose achieves an inverted trapezoidal structure, which can not only facilitate debonding and peeling, reduce the difficulty of the peeling process, improve the peeling yield, but also reduce the colloid residue formed by film breakage, thereby improving the edge roughness; A conductive layer is formed on the surface of the electron beam resist composite layer, which can effectively divert the charge accumulation formed on the surface of the sample by the electron beam during the exposure process, so that the charge can be diverted to the outside of the sample through the probe on the sample holder, so as to avoid the charge accumulation after Form a micro-electric field, avoid the phenomenon of electron beam positioning error and surface spark discharge, and ensure that the transfer process of the design pattern can be effectively transferred to the colloid; in the process of developing and peeling, only the double-layer adhesive needs to be developed and removed in a single time. , with high production efficiency and yield.

The preparation method of the high-performance high-frequency surface acoustic wave device based on electron beam exposure of the present invention has the advantages of simple and easy-to-use process, high productivity, good repeatability and high yield, and is suitable for the preparation of batch high-performance high-frequency SAW devices.

The above-mentioned embodiments merely illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed in the present invention should still 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 in that, comprises the following steps: An insulating composite substrate is provided, the insulating composite substrate includes a support substrate and a piezoelectric thin film on the support substrate; performing 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 comprising a first electron beam resist layer and a second electron beam resist layer on the first electron beam resist layer Floor; forming a conductive layer on the upper surface of the electron beam resist composite layer; performing electron beam exposure, forming a first trench in the first electron beam resist layer and forming a second trench in the second electron beam resist layer, the first trench and the second trench connected to 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; depositing a metal layer; The electron beam resist composite layer is removed by a lift-off process, and interdigitated electrodes are formed on the insulating composite substrate. 2. The preparation method according to claim 1, wherein the supporting substrate comprises one of a silicon substrate, a silicon carbide substrate, a diamond substrate and a sapphire substrate; the piezoelectric film comprises niobium One of lithium oxide, potassium niobate, lithium tantalate, zinc oxide, quartz and aluminum nitride. 3 . The preparation method according to claim 1 , wherein the step of performing surface tackifying treatment on the insulating composite substrate comprises using Surpass4000 tackifier to perform the surface tackifying treatment to increase the electron beam resistance. 4 . The surface adhesion of the etched composite layer to the insulating composite substrate. 4 . The preparation method according to claim 1 , wherein the exposure center dose of the first electron beam resist layer is greater than the exposure center dose of the second electron beam resist layer. 5 . 5 . The preparation method according to claim 1 , wherein the first electron beam resist layer comprises a ZEP520A electron beam resist layer, and the second electron beam resist layer comprises an ARP6200 electron beam resist layer. 6 . 6. The preparation method according to claim 5, characterized in that: comprising using o-xylene to develop, and comprising using NMP solvent to carry out sol stripping. 7 . The preparation 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 . 8 . The preparation method according to 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 . 9. preparation method according to claim 1 is characterized in that: when carrying out described electron beam exposure, comprise the following steps: Use layout design software to design target graphics and obtain layout; The layout is corrected using proximity effect parameters and converted into an electron beam exposure target file format to perform data conversion on the layout. 10 . The preparation method according to claim 1 , wherein the formed interdigital electrodes comprise Al interdigitated electrodes, wherein the interdigital line widths include 150-500 nm. 11 .

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