Thursday, March 19, 2015

Qimonda’s late legacy: 28nm FeRAM using ALD Ferroelectric HfO2

Qimonda’s late legacy: 28nm FeRAM
By Julien Happich
Electronic Engineering Times Europe January 2015 27
CMOS-COMPATIBLE 28 NM FERAM could become commercially available within three to five years, according to research from a collaborative project between NaMLab at TU Dresden, the Fraunhofer Institute for Photonic Micro Systems (IPMS) and GlobalFoundries. Indeed, smashing all prior research claims on FeRAM and scalable to geometries an order of magnitude smaller than today’s 130nm FeRAM commercial offerings, the results are so promising that they are being included in the current version of the International Technology Roadmap for Semiconductors (ITRS).
A result of a sub-project called ‘Cool Memory’ at Saxonys’ cluster Cool Silicon, the technology relies on newly found ferroelectric effects in doped Hafnium oxide (HfO2). Considering that Hafnium oxide is already commonly used as a high-k gate dielectric in CMOS transistors, the processes are pretty much already in place for its ferroelectric variant, readily scalable with CMOS transistors. So why look at doped Hafnium oxide in the first place? We asked Dr. Thomas Mikolajiick, Professor for Nanoelectronic Materials and Director of the NaMLab, coordinator for Cool Silicon.
“This research goes back to 2007 at DRAM maker Qimonda, when a PhD candidate Tim Böscke was doing research to improve HfO2 as a high-k dielectric for capacitors in dynamic random access memories, using dopants to stabilize the material”, explained Mikolajiick. “At certain dopant concentrations and under specific treatments, Böscke noticed that strange peaks occurred in the CV characteristic of the material, and that it behaved as a ferroelectric. This was totally unexpected!

Full story as a PDF can be downloaded here.