An interconnect structure and a method for forming it is disclosed. In one aspect, the method includes the steps of providing a first entity. The first entity includes a first set of line structures. The first set of line structures include a first set of conductive lines, and a first set of dielectric lines made of a first dielectric material and aligned with and overlaying the first set of conductive lines. The first entity also includes gaps separating the line structures and filled with a second dielectric material of such a nature that the first dielectric material can be selectively etched with respect to the second dielectric material. The method also includes providing a patterned mask on the first entity. The method further includes etching selectively the first dielectric material through the patterned mask so as to form one or more vias in the first dielectric material. The method also includes removing the patterned mask.