December 14, 2011 -- During the recent IEEE International Electron Devices Meeting (IEDM), imec presented the world’s smallest, fully-functional HfO₂-based resistive RAM (RRAM) cell, with an area of less than 10 x 10nm². The cell architecture could support future device-level nonvolatile memory.

RRAM is based on the electronic switching of a resistor element material between two stable (low/high) resistive states. Potential advantages could be gained in density and speed over charge-storage-based Flash memory, which is expected to be limited at the 18nm and below nodes.

Imec’s RRAM cell features a novel Hf/HfOx resistive element stack. It couples a cell area of less than 10x10nm² with an excellent reliability (endurance of more than 10⁹cycles). The cell has fast nanosecond-range on/off switching times at low-voltages. It has a large resistive window (>50) and shows no closure of the on/off window after functioning at 200°C for 30 hours. The device remained operating failure-free functioning for 30 hours with a thermal stress of 250°C. The switching energy per bit is below 0.1pJ, and AC operating voltages are well below 3V.

imec also further clarified the impact of film crystallinity on the operation of RRAM cells, especially with a view on further scaling. It also sheds light on the role of the cap layer and on the switching mechanisms.

These results were obtained in cooperation with imec’s key partners in its core CMOS programs Globalfoundries, INTEL, Micron, Panasonic, Samsung, TSMC, Elpida, Hynix, Fujitsu and Sony.

Imec performs world-leading research in nanoelectronics. Further information on imec can be found at www.imec.be.

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