A method for forming, in an integrated circuit, a localized region of a material difficult to etch, including the steps of forming a first silicon oxide layer having a thickness smaller than 1 nm on a silicon substrate; depositing, on the first layer, a second layer selectively etchable with respect to the first layer; forming in the second layer an opening according to the pattern of said localized region; selectively growing on the second layer, around the opening, a germanium layer, the material of the second layer being chosen to enable this selective growth, whereby there exists in the germanium an opening conformable with the above opening; depositing the material difficult to etch so that it does not deposit on the germanium; depositing a conductive layer to fill the opening in the germanium; performing a leveling to expose the germanium; and removing the germanium and the first and second layers.