The award procedure described here concerns the procurement of a combined system for the deposition of thin films by means of magnetron sputtering (DC and RF) and/or vapor deposition (electron beam evaporation and thermal evaporation) of various ultrapure metals, alloys, semiconductors and insulators in ultra-high vacuum (residual gas pressure p < 5 x 10-9 mbar) for the investigation of two-dimensional materials in quantum physics experiments.

The deposition of thin metallic layers is used to contact stacked 2D materials such as graphene or transition metal dichalcogenides (TMD). On the other hand, such films are used as mask material for subsequent etching processes. As part of the Munich Quantum Valley Initiative, the Chair of Efetov, Ludwig-Maximilians-University Munich, Faculty of Physics, will produce a variety of novel two-dimensional materials and investigate them for their electrical, magnetic, optical and thermal properties at very low temperatures.

In order to be able to produce nanoscale structures, the so-called lift-off process is used, in which the deposition takes place via a structured polymer film, usually PMMA. Subsequent immersion in a suitable solvent causes the polymer to be removed and the material applied to it to be removed. The part of the deposited material in contact with the substrate adheres.

In order to carry out this process, the coating source and the specimen to be coated must be arranged in relation to each other in such a way that the deposition is directional/directed and prevents shading of the structures. For the sputtering process, this means a planar/parallel arrangement of target and substrate. For vapor deposition, the sample must be able to be aligned centrally over the source.

In order to avoid cross-linking of the polymer films used and to reduce thermal stress, the substrate temperature must be limited to a maximum of 50 °C by cooling during the coating process and must be able to be controlled.

For the two processes, sputtering and vapor deposition, two different chambers optimized for the specific requirements will be available, which will be connected to each other via a common airlock. This should make it possible to combine the processes without breaking the vacuum. The combination of these methods is of interest, as they can be used in a complementary manner. While vapor deposition is the more advantageous method for lift-off processes thanks to its high directionality, materials are available for sputtering that elude vapor deposition due to their extremely high boiling point (e.g. glass and ceramics) or alloys whose components have different vapor pressures and would separate accordingly.