Effect of VLSI interconnect layout on electromigration performance

We characterized the reliability of multiple-via contacts, as well as the impact of the contact current direction on the failure statistics and short-length effects in Ti-Al(Cu)-Ti-TiN lines. A significant difference between the sheet resistances of the top and bottom shunting layers results in a bimodal failure time distribution for the downward electron flow direction. It also causes a significant difference in the short-length resistance saturation for the two current directions.