Fluorine is deposited on a semiconductor substrate surface according to a novel process. A semiconductor substrate is placed in a reaction chamber and the substrate surface is wetted with water and/or alcohol. A compound containing fluorine is led to the substrate surface, so that a cleaned semiconductor surface covered with fluorine is produced, and the compound containing fluorine is removed from the reaction chamber. The cleaned semiconductor surface covered with fluorine is then wetted with a mixture containing at least 10% by volume of water and at least 10% by volume of alcohol, for producing a cleaned semiconductor surface covered with a predetermined amount of fluorine. The predetermined amount of fluorine is lower the higher a proportion of water in the mixture is chosen to be. Then, the water and the alcohol are removed from the semiconductor surface.