The electromigration performance of Al-1Si-0.04%Cu and Al-1Si-0.5%Cu alloys was investigated. The addition of 0.04 or 0.5%Cu markedly increased the mean time to failure during electromigration tests. When the 0.5%Cu alloy was sputtered in contaminated Ar, a considerably lower mean time to failure was found. The use of X-ray diffractometry revealed a preferred (111)Al orientation of the layers which were deposited in pure Ar. The films which were deposited in contaminated Ar also exhibited other orientations, such as (200)Al. This texture led to lower mean times to failure. In the case of the 0.04%Cu alloy, a larger spread of the distribution of electromigration tests was observed. However, this resulted in a lower expected lifetime. Although only the preferred (111)Al orientation was observed in X-ray diffractometry scans, rocking curve measurements revealed a double distribution of the (111)Al orientation. This was attributed to deposition of the layers in 2 cycles; thus disrupting the single (111) growth into 2 distributions. The disrupted preferred single (111)Al growth then led to a larger spread in the electromigration test results. This was an additional effect of texture upon the electromigration behavior of Al alloys.

An Additional Effect of Texture on the Electromigration Behavior of Aluminium. A.M.Dorgelo, J.A.M.W.Vroemen, R.A.M.Wolters: Microelectronic Engineering, 2001, 55[1-4], 337-40