Abstract: To reduce the use of expensive reactive gas, which is frequently also environmentally harmful, during etching by a plasma the reactive gas is first fed through a reaction chamber of an etching system for stabilization, until all the process parameters are adjusted to their setpoints. During this stabilization, all of the setting parameters of the etching system are stored in a memory. After storage, the gas flow rate of an inert gas, for example helium, that is fed through the reaction chamber instead of reactive gas is raised from an initial value until the reference gas flow rate is found that causes the same setting parameters as the reactive gas. This reference gas flow rate is also stored in the memory.