Reactive Ion Etching

For the projects currently being carried out at the chair, the fabrication of freestanding waveguides using "Faraday Cage Etching" is central. This complex process requires two completely different etching regimes in the same chamber. Accordingly, decoupled plasma density and ion energy (for p-i-n diode integration) are needed. Further research projects require active helium backside cooling (for nanophotonic waveguides) to prevent "flowing" or burning of the electron beam resist (E-beam lacquer). For additional projects as well as for the post-processing of FIB-implanted defects, the preservation of crystal quality is of utmost importance. High-energy ion bombardment would damage the lattice and destroy the optical coherence of the color centers. Gentle removal of surface layers ("Soft Etch") without introducing new defects deep into the crystal is important. Finally, a pure oxygen plasma is needed for the structuring of Solid Immersion Lenses (SILs) in diamond, while SiC requires fluorine chemistry (SF₆/CHF₃). Accordingly, a gas box with at least 5 lines for fluorine and oxygen processes is necessary to process both material classes without hardware modification. An "Open Load" design is also the technically most sensible solution for the planned mode of operation (processing small fragment samples on carrier wafers), as it does not require complex adaptation of robot handling systems to irregular sample geometries, unlike load-lock systems.