Formation of PZT thin-film capacitors over W-plugs and low-voltage operation for high-density LSIs

Formation of PZT thin-film capacitors over W-plugs and low-voltage operatio n were investigated. According to the oxygen depth profiles of the oxygen-a nnealed Ir films by SIMS, oxygen does not diffuse deeply into Ir films even at 700 degrees C. When a sol-gel PZT thin film was processed at 650 degree s C in oxygen, Ir/PZT/Ir/TiN/W-plug structure was successfully formed witho ut any process damages of TiN and W-plugs as a result of excellent oxygen b arrier effects of Ir film. On the other hand, operation of PZT thin-film ca pacitors at 1.5 V was successfully demonstrated by using PZT thin films wit h Ti-rich composition. It was shown experimentally that the saturation volt age of remanent polarization is lowered with increasing Ti/Zr ratio, reduci ng the thickness of the PZT film. In addition a PZT thin-film capacity oper ating at 1.5 V showed excellent switching, retention, and endurance propert ies. (C) 2000 Scripta Technica.