Enabling technology for high-quality piezoMEMS

With the Internet of Things (IoT) concept, the demand for different sensors, sensor networks and wireless solutions has increased rapidly. Often the demand is for small size (measures in millimetres) solutions that makes it demanding for the sensor and electronics suppliers as well as packaging companies to fit everything in small package. Further, there is a need for self-powered solutions that could operate for several years without changing of batteries. ENPIEZOs aim was to develop piezoelectric-based energy-harvesting devices to provide a remote source of electricity from vibrations with countless applications based on a piezoelectric micro-electromechanical system (piezoMEMS). For instance, energy-harvesting devices can be driven by heartbeats to deliver power to implantable sensors or sensors at remote locations like wind-turbine blades. Fabrication-friendly pulsed-laser deposition (PLD) of high-quality epitaxial PbMg(1/3)Nb(2/3)O3-PbTiO3 (PMN-PT) thin films on silicon was developed. The study was performed using SINTEFs wafer scale PLD system, the first of its kind in the world. Delicate engineering of the interfaces between the silicon wafer and PMN-PT using several buffer layers was necessary to obtain the needed film quality. For energy harvesters using thin film PMN-PT it was found through modelling that a design with interdigital top-electrodes and no bottom electrode will be most efficient. This has not been realized before and published works are based on always having a bottom and top electrode. SINTEF has successfully developed a template stack based on yttrium stabilized Zirconia (YSZ), Ceria (CeO2) and Strontium Titanate (STO) that enables transferring the epitaxial state of the single crystal silicon wafer to the active PMN-PT thin film. SINTEF is one of the first that has been able to make such complicated epitaxial thin film stacks on full 150 mm silicon wafers. The method has until now been restricted to an area of ~2 cm. In addition to realizing the MEMS energy harvesters this is a very important step towards using PLD as a method for fabrication of MEMS systems with various functional oxides.

SINTEF har laget en plattform for å integrere epitaksielle funksjonelle perovskitter med 150 mm Si-skiver. Dette er et viktig skritt for at slike materialer, som tidligere bare er studert på substrater opp til 10 x 10 mm, kan brukes i prosesser som egner seg for produksjon av komponenter. SINTEF bruker kompetansen i andre prosjekter som f.eks. H2020 PETMEM som potensielt kan bane vei for prosessorer som bruker 10-50 x mindre strøm dagens teknologi basert på CMOS. SINTEF vil bruke kompetansen videre til å både etablere prosjekter som omhandler energihøsting spesielt og mer på systemnivå der energihøstere er en del av dette. Energihøsting fra vibrasjoner ha mange bruksområder innen digitalisering. SINTEF opplever at etterspørselen etter ulike sensorer, sensornettverk og trådløse løsninger økt raskt. Vi ser det for veldig sannsynlig at dette vil finne veien til både etablerte og oppstartsbedrifter i Norge.

ENPIEZO aims to develop piezoelectric-based energy-harvesting devices to provide a remote source of electricity from waste vibrations with countless applications. For instance, energy-harvesting devices can be powered by a heartbeat to operate pace-makers or it can provide electricity for sensors at remote locations like wind-turbine air blades. Fabrication-friendly pulsed-laser deposition of high-quality PbMg(1/3)Nb(2/3)O3-PbTiO3 thin films on silicon will be developed, based on the delicate engineering of silicon-oxide interfaces. The study will be performed on laboratory- and industrial-scale systems, the first of its kind in the world, which is believed to result in a breakthrough for the production of energy-harvesting devices with state-of-the-art p erformance. In the project, aerosol deposition and environmentally friendly Na0.5Bi0.5TiO3-based piezoelectric alternatives will also be investigated. The project brings together four partners with expertise in a very diverse field of research and develop ment.