Method of manufacturing ferroelectric bismuth layered oxides

Abstract

A semiconductor manufacturing method is directed to forming a ferroelectric film, and in particular a ferroelectric film of the bismuth layer structure type, that has a significant component of reversible polarization perpendicular to the plane of the electrodes. The manufacturing method is conducted at low temperatures on commercially suitable electrodes and is compatible with conventional CMOS fabrication techniques. A ferroelectric strontium-bismuth-tantalate ('SBT') film is formed using two sputtering targets. A first sputtering target is comprised primarily of bismuth oxide (Bi.sub.2 O.sub.3) and a second sputtering target is comprised primarily of SBT. An initial layer of bismuth oxide is formed on the bottom electrode of a ferroelectric capacitor stack. The initial layer of bismuth oxide is directly followed by a sputtered layer of SBT. A second layer of bismuth oxide is then applied and the layers are alternated in a 'layer cake' fashion containing a plurality of layers until a desired thickness of the film is attained. At the end of the deposition, a crystallization anneal is performed to make the film ferroelectric. Once the ferroelectric film is in place, the top electrode is formed and the remaining processing steps are completed.