Correlation between electromigration and Cu-contact angle after de-wetting

An alternative, and quicker way of assessing the electromigration (EM) reliability of Cu interconnects is investigated. It is based on observations of de-wetting and contact angle measurement of Cu thin films. Contact angle results are compared to EM tests, and the correlation between Cu de-wetting and electromigration performance is demonstrated. PVD TaN"x/Ta or ALD TaN barrier layers are tested, while the seed layer is either pure copper or a CuAl"1" "a"t"%. In addition, three types of barrier treatments are investigated: different exposure times to plasma of ALD TaN; tantalum flash between ALD TaN and pure copper seed deposition; ALD TaN exposure to atmospheric oxygen.