There is provided a method for forming a metal interlayer via, comprising: forming a seed layer on a first dielectric layer and a first metal layer embedded in the first dielectric layer; forming a mask pattern on the seed layer to expose a portion of the seed layer covering some of the first metal layer; growing a second metal layer on the exposed portion of the seed layer; removing the mask pattern and a portion of the seed layer carrying the mask pattern to expose side walls of the second metal layer, a portion of the first metal layer and the first dielectric layer; forming an insulating barrier layer on the side walls, the portion of the first metal layer and the first dielectric layer. There is also provided a method for forming a metal interconnection line. Both of them can suppress the occurrence of voids. There is further provided a metal interconnection structure comprising a contact plug, a via and a metal interconnection line, wherein the via is formed on the metal interconnection line, the metal gate and/or the contact plug.