Method for preparing high-performance surface acoustic wave device with multilayer film structure

Abstract

The invention discloses a method for preparing a high-performance surface acoustic wave device with a multilayer film structure. In the invention, a substrate is a CVD (Chemical Vapor Deposition) diamond film, and the surface of the CVD diamond film forms a layer of h-BN (hexagonal boron nitride) film. The film is deposited by adopting a vacuum sputtering method, and the substrate of the film is a mirror polishing silicon substrate. The crystal face index is 100, the base pressure of a vacuum sputtering room is 5X10-4Pa, and the target material for sputtering is hot-pressed h-BN with purity of 99.99%, wherein the hot-pressed h-BN with purity of 99.99% comprises the preparation steps of: depositing a boron nitride underlayer rich in B, then changing the negative bias value of the substrate from 0V to 100V, and finally prolonging the sputtering deposition time to 80 minutes under the condition of keeping process conditions unchanged. Compared with the prior art, the method has the advantages that the equipment used in the preparation method is simple, the process conditions are convenient and easy, and the preparation method is beneficial to large-scale application and has important significance in both production and practice.

Description

technical field [0001] The invention relates to the technical field of surface acoustic wave devices, in particular to a preparation method of a high-performance multilayer film structure surface acoustic wave device. Background technique [0002] In recent years, the rapid development of mobile communication has made radio communication frequency band a limited and precious natural resource. For mobile communication systems, the frequency band below 1GHz has been fully occupied (the first generation digital system); the frequency of the second generation digital system is from 900MHz to 1.9GHz; in the third generation digital system, the global roaming frequency range is 1.8~2.2GHz, the satellite positioning system (GPS) frequency is 1.575GHz, and the application frequency range of low earth orbit new satellite communication (LEO) is 1.6GHz~2.5GHz. Therefore, the application frequency of the current mobile communication system is getting higher and higher , there is an urg...

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Problems solved by technology

[0003] Conventional SAW materials (such as quartz, lithium niobate LiNbO 3 , zinc oxide ZnO, etc.), the surface acoustic wave phase velocity is low (both lower than 4000m / s), and the SAW device with a frequency of 2.5GHz is made with it, and the finger width d of the interdigital transducer (IDT) must be less than 0.4μm The IDT finger width d corresponding to a SAW device with a frequency of 5 GHz is less than 0.2 μm, which is already approaching the limit of the current semiconductor industry level. This problem seriously restricts the further improvement of the frequency of SAW devices; moreover, the transmitter (TX) filter of the mobile communication system filters high-power signals, such a thin IDT finger width d, large resistance, will generate a large number of Heat dissipation, coupled with the low thermal conductivity of these conventional SAW materials, so they cannot withstand high power, which makes it difficult for SAW devices made of the above conventional SAW materials to meet the requirements of high-frequency and / or high-power mobile communications

At present, in the high-performance multi-layer thin-film structure surface acoustic wave devices, the adhesion between each layer of film is poor, resulting in unstable product quality, which is not conducive to large-scale promotion and application, etc.

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