Materials characterization of WNxCy, WNx and WCx films for advanced barriers

A ternary WNxCy system was deposited in a thermal ALD (atomic layer deposition) reactor from ASM at 300 degrees C in a process sequence using tungsten hexafluoride (WF6), triethyl borane (TEB) and ammonia (NH3) as precursors. The WC, layers were deposited by a novel ALD process at a process temperature of 250 degrees C. The WNx layers were deposited at 375 degrees C using bis(tert-butylimido)-bis-(dimethylamido)tungsten ((BuN)-Bu-t)(2)(Me2N)(2)W (imido-amido) and NH3 as precursors. WNx grows faster on plasma enhanced chemical vapor deposition (PECVD) oxide than WCx does on chemical oxide. WNxCy grows better on PECVD oxide than on thermal oxide, which is opposite of what is seen for WNx. In the case of the ternary WNxCy system, the scalability towards thinner layers and galvanic corrosion behavior are disadvantages for the incorporation of the layer into Cu interconnects. ALD WC, based barriers have a low resistivity, but galvanic corrosion in a model slurry solution of 15% peroxide (H2O2) is a potential problem. Higher resistivity values are determined for the binary WNx layers. WNx shows a constant composition and density throughout the layer. (C) 2007 Published by Elsevier B.V