Ag metallization with high electromigration resistance for ULSI

Electromigration is investigated for sputtered Ag lines patterned by a novel hybrid etching technique. This new patterning technique works in two steps. After employing an oxygen plasma in the first step, a hydrogen peroxide solution is used in the second step. The electromigration is tested by an accelerated stress test. It was found that Ag lines show an increased electromigration resistance in comparison to chemical vapor deposition- and PVD-Cu lines from literature. The lifetime values of the lines show variations between different testchips. This is assumed to be due to thermal induced stress voiding in the lines. This can be prevented by improving the adhesion properties by applying suitable etching conditions or an additional adhesion layer.