Morphology evolution in TiN/Al–0.5Cu/Ti interconnection during chamber long stay and post-deposition annealing correlated to defect formation in metallization processing

TiN/Al–0.5Cu/Ti film stacks deposited on SiO2 substrate were studied by X-ray diffraction and electron microscopy to clarify the effects of the chamber long stay and post-deposition annealing on the morphology evolution. Experimental results indicated that the chamber idleness at 270 °C resulted in significant Al2Cu precipitation and hillock growth for the Al–Cu films, which enhanced the occurrence rate of the microcorrosion-induced bridging defects and caused yield degradation on production line while post-deposition annealing at 400 °C for 30 min was proven to effectively regain good yield for the chamber-idled wafers. The yield recovery could be attributed to the fast Al2Cu dissolution and hillock mitigation at the annealing temperature. The electrical sheet resistance of the Al–Cu films would somewhat increase due to the formation of the Al3Ti phase during annealing, but the Al2Cu precipitates and surface hillocks formed during chamber idleness would scarcely change the electrical property of the films. This study suggests that the evolutions of second phase and surface hillocks can be controlled by the processing duration and post-deposition treatment rather than the deposition temperature or Cu addition amount of Al–Cu alloy.