known from U.S. Pat. No. 5,451,543, wherein a dielectric material, i.e. silicon nitride or aluminum oxide, or a conductive material, i.e. tungsten, titanium nitride or tantalum nitride, is used for the etch stop layer. [0008] A disadvantage of the use of tungsten, titanium nitride or tantalum nitride for the etch stop layer is that metallic polymers are formed during etching of the via in the diel