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

Abstract

Formation of PZT thin‐film capacitors over W‐plugs and low‐voltage operation were investigated. According to the oxygen depth profiles of the oxygen‐annealed Ir films by SIMS, oxygen does not diffuse deeply into Ir films even at 700 °C. When a sol‐gel PZT thin film was processed at 650 °C in oxygen, Ir/PZT/Ir/TiN/W‐plug structure was successfully formed without any process damages of TiN and W‐plugs as a result of excellent oxygen barrier effects of Ir film. On the other hand, operation of PZT thin‐film capacitors at 1.5 V was successfully demonstrated by using PZT thin films with Ti‐rich composition. It was shown experimentally that the saturation voltage of remanent polarization is lowered with increasing Ti/Zr ratio, reducing the thickness of the PZT film. In addition a PZT thin‐film capacitor operating at 1.5 V showed excellent switching, retention, and endurance properties. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(8): 1–7, 2000