New Material for FeRAMs
Peter Singer, Editor-in-Chief -- Semiconductor International, 9/1/2006
The Tokyo Institute of Technology and Fujitsu have jointly developed a material for a new generation of non-volatile ferroelectric random access memory (FeRAM). The material is a modified composition of bismuth ferrite (BiFeO3 or BFO), which enables data storage capacity up to 5× greater than the materials currently used in FeRAM production.
Fujitsu reported that the new FeRAMs can be produced with the company's 65 nm process technology using the BFO-based material in a device structure similar to the one used to build FeRAMs using 180 nm technology. FeRAMs using this material can provide memory cell capacity up to 256 Mb.
BFO is composed of bismuth, iron and oxygen atoms with a perovskite structure. Lead zirconate titanate (PZT or Pb(Zr,Ti)O3) is now used as a ferroelectric material, but it has a lower charge-storage capability, so it also has limited scalability. The technology limits of PZT are ex-pected to occur at the 130 nm node because, as cell area decreases, higher polarization is required. This limit is expected to be reached in 2009.
A manganese-doped BFO thin-film capacitor was developed with the dual functions of decreasing leakage current and 180-220 µC/cm2 of switching charge (Qsw), which is equivalent to twice the remaining polarization. These results clearly indicate significant scalability potential for future technology nodes.
Get more information on emerging technologies.
