In microchip production the highest possible purity of working media and the environment are required. The higher the quality of the semiconductors, the lower are the admissible limiting values for particles and chemical contamination. This effects both the production of the wafers, which are silicon discs on which the switching circuits of the microchips are etched which are sawed out into individual microchips later, and also the production of process materials. The so-called wet benches are production areas where the surfaces of the silicon discs are ground, the switching circuits are etched on with high purity acids and mixed acids and rinsed with high purity water.