Reactive Ion Etcher for cryo processes

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The central nanostructure laboratory of the University of Konstanz (nano.lab) applies for reactive ion etching facility, which will replace an existing device from 2001 and will expand the possibilities of the nano.lab. The existing plant is only used for very special and very isotropic etching processes, as it is optimized for working under high process pressures. Anisotropic etching profiles cannot be realized with the existing equipment. Even in another existing, somewhat younger plant, anisotropic etching profiles using fluorine chemistry are only possible to a very limited extent and further process types cannot be retrofitted. In addition to isotropic etching, the new facility should also allow highly anisotropic etching processes. These etching processes are particularly important for projects in nanomechanics and the production of silicon-based optical waveguides. For these anisotropic processes, polymer-forming process gases are to be used, which enable the sidewalls to be passivated.In addition to the usual radiofrequency source the new facility will be equipped with an ICP (Inductively Coupled Plasma) source. The use of an ICP makes it possible to guarantee a stable plasma with a high density of ions and radicals in the gas even at very low process pressures. Another important advantage for the upcoming research projects is the independent adjustability of plasma density and ion energy (DC bias) during the etching process, which is given by the ICP. This makes it possible to etch at low ion energies with very few defects and very selectively, which also provides optimal control of the etching profiles. This is a technique that bypasses the patented and extremely time-consuming "Bosch process", which has been established for highly anisotropic processes.The new plant is to be operated exclusively with fluorine gases, and the existing plant is to be used exclusively for chlorine processes in the future in order to achieve the necessary reproducibility of the processes and to be able to use the equipment more efficiently. With these two plants, a very wide range of materials can be dry-etched very precisely for a wide range of users in the fields of physics and chemistry.A high degree of precision in the production of the structures is necessary for the implementation of the projects. To ensure this, it is necessary to have maximum control over the relevant process parameters. The equipment of the plant should therefore include a temperature control of the substrate electrode to ensure reproducibility of the results. A substrate electrode that can be controlled over a wide temperature range can also significantly extend the range of applications of the system, since the chemical reactivity can be controlled via the temperature. A laser interferometer will allow in-situ monitoring of the etching depth. In addition, the system should be equipped with dry pumps to guarantee oil-free and clean work.