Reliability assessment of tungsten via to copper interconnect for novel memory device

The reliability assessment of tungsten via to copper interconnect were investigated. Just-landing and un-landing via structure showed similar EM characteristics to full-landing structure. The activation energy of EM is about 0.86 and current density exponent is about 1.9, which means the mechanisms of interfacial diffusivity and line depletion stress. The resistance shifting of all splits was no more than 1% after 1000H SM test. The un-landing via of over-etching formation showed good resistivity and reliability that might be one of the solutions for gaining the process pitch in low-cost memory applications.