Fujitsu, Tokyo U. tout 65nm FeRAM material

August 7, 2006 – Fujitsu Microelectronics America Inc. and the Tokyo Institute of Technology say they have developed a new material for use with non-volatile ferroelectric random access memory (FeRAM) targeting 65nm manufacturing processes, enabling up to 5x greater data storage capacity than materials currently used in FeRAM production.

New FeRAMs with 256Mbit memory cell capacity can be produced with Fujitsu’s 65nm process and the composite of bismuth ferrite (BFO), in a device structure similar to FeRAMs built using the company’s 0.18-micron technology, Fujitsu stated. Engineering samples are expected to start shipping sometime in 2009. The joint research is supported in part by a grant from Japan’s Ministry of Education, Culture, Sports, Science and Technology (MEXT), via the Japan Science and Technology Agency (JST).

The composite, a ferroelectric material composed of bismuth, iron and oxygen atoms (BiFeO3) with a perovskite structure. Lead zirconate titanate (PZT) is currently used as a ferroelectric material, but it has a lower-charge storage capability, and thus limited scalability, according to the company. At the 0.13-micron node, the material runs into technology limitations — as cell area decreases, higher polarization is required — and the wall is expected to be reached by 2009.

The Fujitsu-Tokyo Tech research teams developed an Mn-doped BFO thin-film capacitor with dual functions of decreasing leakage current and 180-220µm C/cm2) of switching charge (Qsw), equivalent to 2x the remanent polarization (2Pr), indicating scalability potential for future technology nodes, Fujitsu said. FeRAMs built with 65nm process technology can be produced using Mn-doped BFO, with similar device structure to the 0.18-µm-based FeRAMs, while also providing significant scalability, enabling large memory capacity up to 2014.

Further development of BFO is seen enabling large-capacity 256Mbit FeRAMs with densities of two orders higher compared with the current capacity of 1Mbits, Fujitsu stated. The increased density will open inroads into applications in security as well as new domains such as “quick-on” computers that can be immediately ready for use without slow start-up processes, as well as electronic paper devices that let users browse and read a large volume of information traditionally written on plain paper.


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