A Study of Low Temperature Al Sputter Process Electromigration Lifetime

As 8 inch fab moves to 0.13µm process and beyond, backend Aluminum line width also shrinks to 0.14µm or below with much tightened overlay spec. Low temperature Al sputter process shows very smooth metal surface, which significantly improves overly mark recognition. Thus cold Al is preferred. Meanwhile Cold Al electromigration lifetime is worse than that of hot Al due to smaller aluminum grain size. Cold Al EM must be well controlled for production. In this article, we study the backend HDP oxide deposition temperature and its influence on Metal-1 EM lifetime based on fab 0.13µm process, and a strong correlation has been found. From which, a suitable HDP temp control can be set for cold Al mass production.