CVD tin barrier layer for reduced electromigration of aluminum plugs

摘要

A structure and method incorporating a CVD TiN barrier layer 230 over the aluminum plug 220 in order to prevent the high plug resistance caused by the blanket metal film stack 240, 250, and 260 deposition process. Unlike physical vapor deposited (PVD) TiN, CVD TiN 230 does not react with the aluminum 220 during annealing. CVD TiN has also been shown to be a better diffusion barrier for aluminum than PVD TiN. In addition, CVD TiN will disrupt any unfavorable grain boundary propagation through the aluminum plug which may act as a source of electromigration failure. Therefore, the CVD TiN 230 can increase the electromigration resistance, without increasing the contact/via resistance.