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In this paper, the reliability requirements, thermal behaviour and failure mechanisms of solidly mounted Bulk Acoustic Wave (BAW) filters are studied. High power RF stress measurements are presented where the evolution of the surface damage of the BAW filters as a function of stress time is analysed by optical height profiling. Two different metal stacks were used. The main failure mechanism for BAW filters during high RF power stress is proposed to be acoustomigration. By comparing the stress measurements to the requirements, excellent reliability of NXP's BAW duplexers is proven.

Thin film ferroelectric capacitors have been integrated with resistors and active functions such as ESD protection into small, miniaturized modules, which enable a board space saving of up to 80%. With the optimum materials and processes, integrated capacitors with capacitance densities of up to 100 nF/mm2 and breakdown voltages of exceeding 90 V have been achieved. The integration of these high density capacitors with extremely high breakdown voltage is a revolution in the world of passive components and has not yet been achieved in any other passive integration technology. Furthermore, thin film tunable capacitors based on barium strontium titanate with high tuning range and high quality factor at 1 GHz have been demonstrated. Finally, piezoelectric thin films for piezoelectric switches with high switching speed have been realized.

Galvanic piezoelectric RF MEMS switches are presented. The switches are completely processed and characterized mechanically and electrically. The mechanic deformation and switching times are discussed. Closing of the switch can be achieved within less than 10 ?s. Electrical measurements yield contact resistances in the order of 50 ? and isolation resistance of more than 1 G?.

Dielectric, ferroelectric and piezoelectric thin films are getting more and more attention for next generation mobile communication and medical systems. Thin film technologies based on dielectric, ferroelectric and piezoelectric thin films enable System-in-Package (SiP) devices, resulting in optimal integration of various functions in one module with respect to high performance, small size and low cost. Within Philips a passive integration platform for SiP technologies is developed, comprising key functions such as RF filters, micro-electromechanical switches, high-value capacitors as well as passive and active functions integrated in small modules. The piezoelectric thin film technologies do not only play a role for RF filters, but are also a breakthrough technology for a new class of thin film ultrasonic transducers.

Piezoelectric AlN and PbZr/sub x/Ti/sub 1-x/O/sub 3/ (PZT) layers are investigated with respect to their potential for HF micro-electronic applications. High quality AlN films with strong c-axis orientation are achieved by optimum deposition conditions and by applying nucleation layers. Electromechanical coupling factors of 0.25/spl plusmn/0.03 have been found. PZT films grown via sol-gel processing show high coupling factors k of 0.4-0.6 and are therefore attractive for wide bandwidth applications.