Crystalline-buffer-layer-aided (CBL) sputtering technique for mega-bit ferroelectric memory devices with SrBi/sub 2/Ta/sub 2/O/sub 9/ capacitors

摘要

A crystalline-buffer-layer-aided (CBL) SrBi/sub 2/Ta/sub 2/O/sub 9/ film deposition using two step sputtering technique has been developed through investigation of the interface structure between the Pt bottom electrode and SrBi/sub 2/Ta/sub 2/O/sub 9/. A layer having an amorphous structure, obtained by the Ar sputtering of the first step, leads to a depletion of Bi at the interface, whereas a crystalline structure, obtained by Ar/O/sub 2/ sputtering of the first step, inhibits such depletion. The two step sputtering deposition process is implemented to form a Bi-rich crystalline interface layer which improves the polarization characteristics. The remnant polarization values was improved up to 10 /spl mu/C/cm/sup 2/ by the modified deposition process.