IMPROVING ELECTROMIGRATION RELIABILITY IN AL-ALLOY LINES

We present a method that utilizes surface topography to control the di stribution of grain sizes, single grain segment lengths and polygrain cluster lengths in AI-Cu thin films. Microstructural data for the grai n size and segment/cluster length distribution parameters are presente d that demonstrate the influence of various topographical features adj acent to conductor lines. Experimental results show the impact of thes e features on electromigration failure times. Our results demonstrate that the relationship between median failure time and segment length i s consistent with the critical threshold length concept for long inter connects containing large numbers of single grain segments and polygra in clusters. These results demonstrate the importance of the segment l ength and type in controlling electromigration mass transport.