The present project put forward the development of technologies for surface and bulk acoustic waves devices (SAW and FBAR), with gigahertz operating frequencies, based on wide band gap (WGB) thin film semiconductors: GaN and AlN.
The last years the development of WGB semicoductors technologies, unlike the calassic SAW devices manufactured on quartz, lithium niobate or lithium tantalite with working frequencies in MHz range, has opened the perspective of manufacturing SAW and FBAR devices for application in the GHz domain, by monolithical integration with different circuit elements and good compatibility with MEMS technologies.The specific properties of GaN and AlN semiconductors all together with the micromicromachining and nanoprocessing technologies which will be developed in the frame of this project, will enhanced the achievement, for the first time, of operating frequencies up to 6 GHz. The direct applications adressed by this project are the 5.2 GHz WLAN and 1.8GHz DCS systems as well as the 4-th generation mobile phones having 3-6 GHz opperating frequency. Althou, SAW and FBAR structures can be used as chemical sensors extremely sensitive respective to the adssorbed mass. Carbon nano tubes (CNT) will be used as adsorbing layer. This sensitivity of type of sensors depend directily with the frequency square (f2) therefore we expect an important increase of the sensitivity with the frequency.
Over the last few years important progresses in material development of high quality nitride layers though material engineering by MOCVD and MBE, but high quality thin AlN or GaN films have not been reached, not at the level of reproducibility and quality of the silicon or GaAs technology.
The project aims to obtain high quality (mechanical as well as electrical properties) AlN layers by magnetron sputtering techniques on high resistivity silicon substrate. One challenge goal of this project is the micromachined submicron AlN membranes, in order to achieve the microwave properties of the proposed FBAR devices. These membranes have to be self-sustainable and to support metalisation, despite their thickness under 0.5 μm. Concerning the SAW devices with operating frequencies 2-6GHz, nanolithography will be used for the definition and fabrication of these devices (150-300nm width for metallization lines; IDT-interdigital transducer topology).
The project is a challenge not only for the technological processes but also for the simulations, the modelling and design methods which will be developed. The final goals of GIGASABAR will be 3 experimental models: SAW and FBAR type resonators for applications in 2-6 GHz advanced communications as well as an acoustic wave device (SAW or FBAR) with CNT as adsorbing coating, to be used as chemical sensor for ethanol.
The consortium consist of: National Institute R&D for Microtechnologies-IMT (one of the promoters of the RF MEMS domain in Europe, coordinator of the European successful project in this domain MEMSWAVE, participant in FP6 NoE in RF MEMS AMICOM and in FP7/STREP, MEMS 4 MMIC ); National Institute R&D for Material Sciences-INCDFM (with excellent expertise in materials science); Polytechnical University-UPB and Ovidius University-UOC having well known results in RFMEMS domain (design and characterization microwaves circuits); the SME SITEX 45 SRL. This consortium will achieve the critical mass for the realization of this project, the possibility of an efficient dissemination activity and the premises of a future successful participation at the FP7 EC Programs.
