Ruediger Mauczok

Integrated ferroelectric stacked mim capacitors with 100 nF/mm 2 and 90 V breakdown as replacement for discretes

This paper shows for the first time integrated thin film ferroelectric metal-insulator-metal capacitors on silicon with a record high capacitance density above 100 nF/mm2 combined with a breakdown voltage of 90 V and a lifetime exceeding 10 years at 85degC and 5 V. The high capacitance density was obtained by a combination of material optimizations resulting in a dielectric constant of 1600, and stacking of capacitors. The reliability of these ferroelectric capacitors was studied in detail with accelerated lifetime testing. The high performance of the integrated capacitors in this paper shows great potential for applications demanding high capacitance densities combined with electrostatic discharge protection.

Piezoelectric Thin Films: A Technology Platform for Innovative Devices

Ferroelectric, piezoelectric thin film material and processes are gaining more and more importance for innovative devices that are focusing on miniaturization, high performance and integration. A piezoelectric thin film MEMs platform has been developed that enables miniaturized ultrasound transducers that operate in the frequency range of >50 kHz up to >10 MHz. The thin film ultrasound transducers show a high quality and reliability. With this technology platform ultrasound transducers have been developed that operate at 60–90 kHz and show a coverage >25 m2 at a low operating voltage of 12 V. The same technology platform has been used to realize ultrasound transducer arrays operating at 3–10 MHz. Ultrasound images have been demonstrated with these piezoelectric thin film transducer arrays.

Piezoelectric thin film platform for ultrasound transducer arrays

A piezoelectric thin film MEMs technology platform has been developed that enables processing of miniaturized ultrasound transducer arrays with only minimum 2 mask steps. The thin film ultrasound transducer arrays are operating in the frequency range of >; 50 kHz up to >; 10 MHz. A new class of ultrasound sensors for e.g. proximity sensing and imaging has been developed.

Ultrasonic and thermo-compression gold-to-gold bonding of narrow frames for hermetic cavity sealing and electrical interconnect

Cavity sealing based on ultrasonic or thermo-compression gold-to-gold bonding of rather narrow, 5 to 20 μm wide frames on die-to-wafer level is investigated. The seal quality is tested with an aggressive alkaline etch solution (33% KOH, at 90°C) using an aluminum test layer, which in the case of poor sealing, is readily attacked. Sealing of large cavities (~3×9 mm2) with sealing ring widths of 10 and 20 μm for the ultrasonic as well as sealing of small cavities (70×70 μm2) with a 5 μm wide sealing ring for the thermo-compression bonding is demonstrated. The thermocompression provides better bonding of the narrower features than the ultrasonic technique.

A reliability study on high-breakdown integrated ferroelectric capacitors.

Capacitors, with a capacitance density of up to 100 nF/mm2 and a dielectric constant of 950¿1600 were produced by optimizing the ferroelectric material combined with stacking. Accelerated lifetime (ALT) tests under elevated temperatures of 210¿290°C and dc fields of 25¿250 kV/cm were performed and the lifetime criterion, common for ceramic multilayer capacitors, was employed: The increase of the current density by one order of magnitude is defined as the end of lifetime. The capacitor under these conditions is still functioning and therefore this criterion is more conservative than time dependent dielectric breakdown (TDDB). The activation energy and voltage dependence are determined from the ALT, to extrapolate to operation conditions. Activation energies of 1.1¿1.6 eV have been determined and a dependence on the applied dc voltage was observed. All capacitors showed a lifetime of more than 10 years at 85°C and 5 V.