a passivation layer in some implementations the thickness of the second sub layer 30 is in the range of about 5 000 to about 20 000 u00e5 thus in some implementations the second sub layer 30 may be only several times thicker than the first sub layer 29 in other implementations the second sub layer 30 may be as much as several hundred times as thick as the first sub layer 29 the lower conductive line 28 can be formed for example by a damascene technique such that it is sub stantially planarized alternatively the lower conductive line 28 can be formed by a reactive ion etch rie or etchback process such that the resulting surface has topography the plug 36 and the interconnection 34 can be formed by a dual damascene process which includes etching through the insulating sub layers 29 30 and sub sequently filling in the etched regions with a conductive metal details of the dual damascene process are described in greater detail below with respect to fig3 a 3 b 4 5 a 5 b 6 7 and 8 referring to fig3 a and 3b the formation of the dual damascene structure begins with the sub layers 29 30 already formed over a conductive element in this case the lower conductive line 28 a first photoresist pattern or mask 42 with at least one via opening 44 is provided over.