It was recalled that electromigration failures of W plug contacts had been shown to be strongly affected by the test structure and the stressing conditions. It was concluded that, in order to make realistic lifetime predictions of the behavior under operating conditions, data had to be obtained from test structures which were designed to minimize structural effects.

H.Kawasaki, C.Lee, T.K.Yu: Thin Solid Films, 1994, 253[1-4], 508-12