BLANC - Blanc

Advanced BST based systems – ABSYS

Submission summary

The number of supported frequency bands in telecoms and other wireless devices is growing very fast. As a result, the state of the art of front ends not only leads to high cost and volume but also to poor performance due to the insertion loss, linearity of many cascaded stages and switches in the signal paths. High quality tuned RF performance, compactness, miniaturization, reliability, good power efficiency and excellent temperature stability call for a joint effort in materials development, processing technologies and device concepts. That demands both advanced material engineering and device engineering to work side by side to develop an innovative device topology in terms of functionality and miniaturization process flow. To address these requirements, engineers and chemists should work close together to explore new techniques and materials, as well as getting more from existing technologies and materials. The integration of BST thin films within certain device concept at the interfaces of different materials could give a great impact towards miniaturization of wide tunable RF components. The involvement of different materials to achieve certain functionality demands a huge efforts and analysis of the inherent crystallographic and chemistry incompatibility of the interface of at least two involving materials. Moreover, the defected interface could exhibit a very interesting behavior that could be exploited and merged in specific scenario to improve the overall function of tunability. As previously reported, number of approaches has been tested in the community, but to our knowledge severe penalties always come along with moderately promising performance. Our approach is to combine material engineering with device engineering that call for a joint effort in materials development, processing technologies and device concepts to develop an innovative device topology in terms of functionality and miniaturization process flow. Our main objective in this project is to deeply investigate the interfaces in indium tin oxide (ITO)/BST/ITO heterostructure for tunability. With this specific structure the global tuning of BST film will occur. The basic principle and the novelty of this proposed topology is that the RF signal will not propagate inside the highly resistive indium tin oxide layer and will be confined inside the BST films, whereas the dc applied bias will tune the permittivity of the films which will force the impedance and phase relationships to be changed yielding microwave tunability. The involvement of different materials in addition to the BST materials on the level of functional device, demands huge efforts to analyze the interfaces in order to explain electrical behavior and improve the system. More precisely, crystallographic structure, microstructure and chemical composition of the interfaces have to be studied. In fact, their tunable structural quality could lead to a very interesting behavior that could be exploited and merged in specific scenario to improve the overall function of tunability. On the other side, the project aims at building tunable RF devices such as matching circuits and filters at the interface of low temperature cofired ceramic thick technology (LTCC) and BST thin film. For the integration of BST thin film with LTCC thick film, a considerable technological effort is required to overcome the problem of the roughness of the LTCC which is in the order of magnitude of the BST thin film thickness. To come closer to true integration of BST-based ferroelectric components with LTCC materials, a polishing process is necessary. So far, thick BST cofired with LTCC have been presented the incorporation of BST thin films with LTCC still in its enfancy and up to our knowledge nothing has been reported in this direction. Finally; this project will be conducted by a consortium composed by ICMCB-CNRS laboratory and LAAS-CNRS laboratory. The very short time cycle of the project will need strong and efficient management. After discussions, it is proposed that the project is coordinated by ICMCB as the material interface study which is a very crucial issue, will be done at ICMCB.

Project coordinator

Mario MAGLIONE (CNRS - DELEGATION AQUITAINE LIMOUSIN)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CNRS - DELEGATION AQUITAINE LIMOUSIN
CNRS - DELEGATION REGIONALE MIDI-PYRENEES

Help of the ANR 368,410 euros
Beginning and duration of the scientific project: - 36 Months

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