PVD cluster tool

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Micro- and nanosystems research requires a three-chamber cluster tool for the deposition of co-sputtered metals, reactive sputter layers such as AlN and metal oxides and evaporation. By combining those processes into a cluster, the different processes can be applied to a wafer without loss of vacuum. A comparable system is not yet available, but necessary for future research. The Chair for microsystems technology at Ruhr-Universität Bochum was established in 2017. The former Chair for materials and nanoelectronics has worked on substrates of 1 cm2 size, and the only available PVD process was evaporation. A suitable clean room is available and is currently extended for 200 mm wafer handling.Metals play a key role as wiring, heating elements and temperature sensors for MEMS and are required with reproducible parameters for almost all microsystems processes. Multi-layer systems from metals such as nickel and aluminium at nanometer thickness are also an interesting new alternative for a reactive soldering in the assembly of MEMS.Reactively sputtered layers, especially aluminium nitride (AlN), are an important amendment of functional thin films. AlN is chemically and mechanically stable and exhibits piezoelectric properties, it is deposited with c-axis orientation. It is applied in actuators as well as energy harvesters and allows also highly stable membrane systems on silicon. Evaporation in combination with pre-structured templates causes a kind of glancing angle deposition of self-organizing nanostructures. They show unique properties when applied to microsystems. These properties cannot be reached by sputtering. The requested cluster covers all three basic physical deposition processes for MEMS and allows to deposit arbitrary combinations of layers without leaving the vacuum. The surface oxidation of the sources as well as of the substrates is prevented safely. One of the chambers will carry an inverse sputter etching tool for substrate cleaning before the first deposition takes place. The system is designed for 100 – 200 mm wafer diameter as it has to be compatible to a cluster tool for 2D materials combining atomic layer deposition, atomic layer etching, reactive ion etching and plasma-enhanced chemical vapour deposition. This cluster is currently established within the BMBF ForLab initiative (ForLab-project PICT2DES) and intended for use with 200 mm wafers. It has an interface to the Forschungsfabrik Mikroelektronik Deutschland.