Thin Film Technology
At the IMPT, the field of thin film technology spans the design and production of microsystems/MEMS (actuators and sensors). The underlying effect for most systems is electromagnetism.
The rough design of the systems is carried out through analytic and network-based methods. The detailed design is created using FEM simulations. For this, the multiphysics simulation tool, ANSYS®, is available, which makes it possible to perform simulations in the fields of structural mechanics and electromagnetics as well as thermal and fluid dynamic simulations.
The actuators produced at the IMPT use magnetic fields to generate movements. The actuators are distinguished based on their operating principle (e.g. synchronous (variable) reluctance and hybrid actuators). Linear and rotary micro motors are not only produced, but also researched regarding the use of these magnetic microactuators in the fields of microoptics, magnetic nanoparticles manipulation, and implantology.
Sensors that rely on electromagnetism such as Eddy current sensors, strain sensors, and GMR sensors (ultra-thin, for high-temperature applications), are researched at the IMPT in the field of modular sensors for their use in gentelligent applications, which, amongst others, includes temperature sensors as well.
For the production of microactuators and sensors, usually a combination of photolithography and galvanic deposition is used. By means of photolithography, a temporary form of photoresist is created on Si- or Al203-substrate and filled with functional materials as a result of galvanic deposition. In terms of functional materials, Cu is utilized for coils and wiring. NiFe45/55, NiFe81/19, CoFe and Ni are used for flow leads. Furthermore, epoxy resin SU-8TM and polyimide are used as embedding material and for membranes. For insulation, layers made of Si3N4 and SiO2 are applied, which are produced using PECVD (Plasma Enhanced Chemical Vapor Deposition). Additionally, ion-beam etching and lift-off are employed for structuring. The production of mechanical components (membranes, cantilevers, spring structures …) happens through a combination of lithography and etching processes, for which dry etching processes (e.g. DRIE, plasma) and wet chemical etching (e.g. KOH, HF) are available.