Electromigration improvement with PDL TiN(Si) barrier in copper dual damascene structures

A significant improvement in electromigration performance for copper dual damascene structures was observed with the use of Pulsed Deposition Layer (PDL) TiN(Si) as a copper diffusion barrier layer instead of conventional sputtered (PVD) Ta/TaN. When an Ar sputter preclean was used, copper agglomeration occurred during the high temperature PDL process. An integration method was developed for the PDL film that avoids copper agglomeration on via sidewalls and has minimal barrier at the bottom of the via. The resulting process had lower via resistance, improved via stress migration and longer electromigration lifetime in multi-link testers than PVD Ta/TaN in both SiO₂ and PECVD SiOC low k dielectrics.