MEDCOM: Microwave electro-acoustic devices for mobile and land based communications

• Unité de recherche: PCRD EU
• Numéro de projet: 99.0661
• Titre du projet anglais: MEDCOM: Microwave electro-acoustic devices for mobile and land based communications

Mots-clé (Anglais)

Telecommunication; microwave filters; bulk acoustic waves; piezoelectric; thin films

Autre Numéro de projet (Anglais)

EU project number: IST-1999-11411

Programme de recherche (Anglais)

EU-programme: 5. Frame Research Programme - 1.2.4 Essential technologies and infrastructures

Description succincte (Anglais)

See abstract

Partenaires et organisations internationales (Anglais)

Coordinator: Uppsala University (S)

Résumé des résultats (Abstract) (Anglais)

The general objective of this project is to develop, investigate and test new technologies based on piezoelectric thin films for the fabrication of the next generations of microwave electro-acoustic devices used in mobile and land-based telecommunications. The major part of the project is devoted to Bulk Acoustic Wave (BAW) devices. Alternatively, Surface Acoustic Wave (SAW) devices based on diamond films are investigated as well. Specific objectives include the synthesis of piezoelectric thin films with high coupling coefficients and quality factors, resonator structures with low frequency drifts, and surface acoustic wave structures with high propagation velocities. The most complete study will be made for AlN thin films, ranging from development of an industrial sputter deposition tool to the evaluation of BAW microwave filters working in the range of 2 to 8 GHz. Very demanding specifications are required for the sputter tool: uniformity and thickness reproducibility of better than 1%. The demonstrator represents a frequency up-converter consisting of a voltage-controlled oscillator, a mixer, a low-RF (2-3 GHz) and a high-RF (7-10 GHz) band pass filters The consortium is composed of two companies working in RF components (Philips, Thales), one sputter tool manufacturer (Unaxis), one end-user (Ericson) and two universities working in materials science of thin films (Angstrom-Laboratory of Uppsala university and EPFL).
The main work of EPFL is devoted to the study of specific issues of AlN growth, to the process development, protoype design and manufacturing of BAW filters, and to investigate PZT growth on diamond films for SAW devices, and to integrate PZT in BAW devices. In the second year we investigated the growht of AlN on a metal without fcc lattice: Mo. Its (110) surface disturbs very much the nucleation of hexagonal (001) AlN nucleus. The AlN process had to be run differently for the first nanometers in order to suppress the nucleation of wrong orientations. We arrived as well to grow PZT on diamond films. A special oxygen barrier was applied. Very encouraging results have been obtained with the first 8 GHz resonators. Coupling factor (k2) and quality factor amounted to 5.5% and 500 respectively.
In the future work filters at 8 GHz will be fabricated and analyzed. The PZT/diamond for SAW applications will be optimized and characterized.

Références bases de données (Anglais)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 99.0661