High performance Cu interconnects capped with full-coverage ALD TaNx layer for Cu/low-k (k∼2.5) metallization

Performance of Cu dual damascene interconnects with a full coverage ALD TaNx cap layer coating on the top surface of Cu line has been investigated. With deposition process that generates different ALD TaNx film properties on Cu and low-k dielectrics, 100% yield of line-to-line leakage can be achieved. ALD TaNx cap layer can improve electromigration lifetime by more than 3 times due to improvement of the interface between Cu and cap layer which actually suppress the Cu surface migration without degradation of stress migration performance. This work demonstrates that ALD TaNx cap layer can be successfully integrated with Cu/low-k (k∼2.5) metallization with potential5% reduction in RC delay as compared to conventional cap layer.