Process variations in use for the first generations of FRAM® memory products

Abstract

Ferroelectric memories have been firmly established commercially over the past decade. This paper presents the process variations used by Ramtron for its portion of the worldwide FRAM output and discusses the reasons why the particular process was chosen for each case. The first ferroelectric memory produced in volumes exceeding millions of units was the FM1208 4Kb parallel part in 1992. The exact process for the fabrication of this part at the wafer level involves a combined salicide and silicide process for the successful integration of ferroelectric materials. Furthermore, a special packaging technique is employed to minimize the effect of hydrogen and stress in the plastic packaging mold compound. Current generations of FRAM no longer have the requirement for special processing or materials at assembly. Current generation IC card products are clearly state-of-the art as programmed contents of the chip are easily retained through the card packaging process. Test and quality methods and results are reviewed.