Impact of Ceramic Packaging Anneal on the Reliability of Al Interconnects

Experimental results show conclusive evidence that stress induced metal voids and Si nodules (both of which originate during wafer processing) grow significantly after Ceramic Packaging (CDIP) glass sealing anneal. Furthermore, the growth of a metal void is almost always accompanied by Si precipitation in its immediate neighborhood. The combination of a metal void and an adjacent silicon nodule was observed to significantly reduce the net metal line cross-sectional area and is highly undesirable for interconnect reliability. In this paper the above phenomenon is fully explained and the effects of COIP anneal temperature profiles are examined.