In one embodiment of the disclosure, it is proposed a photolithography device for generating structure on a photoresist substrate, the photolithography device comprising a light illumination unit and a photomask. The photomask is remarkable in that it comprises at least one layer of dielectric material and a medium having a refractive index lower than that of said dielectric material, wherein a surface of said at least one layer of dielectric material has at least one abrupt change of level forming a step, and wherein at least a base and lateral part of said surface, with respect to said step and a propagation direction of an electromagnetic wave from said light illumination unit, is in contact with said medium.