Method for manufacturing electromagnetic radiation reflecting devices, said method comprising the steps of: a) providing a silicon substrate defined by at least one first free surface, b) forming on said first surface a layer of protective material provided with an opening which exposes a region of the first free surface, and c)etching the region of the free surface by means of an anisotropic agent to remove at least one portion of the substrate and define a second free surface of the substrate inclined in relation to said first surface. Furthermore, said first free surface is parallel to the crystalline planes {110} of silicon substrate and said step (c) comprises a progressing step of the anisotropic agent such that the second free surface resulting from the etching step is parallel to the planes {100} of said substrate.