Researchers shrink ferroelectric memory stacks

Researchers in Japan have developed ultrathin ferroelectric capacitors that maintain strong polarization at a stack thickness of just 30 nm, including top and bottom electrodes. Using scandium-doped aluminum nitride films sandwiched between platinum electrodes, the team achieved high remanent polarization, demonstrating the potential for high-density, energy-efficient memory in compact electronic devices.

The work, led by Professor Hiroshi Funakubo of Science Tokyo in collaboration with Canon ANELVA, marks a departure from previous approaches that only thinned the ferroelectric layer. By optimizing the full capacitor stack—5-nm platinum bottom electrode, 20-nm (Al_0.9Sc_0.1)N ferroelectric layer, and 5-nm platinum top electrode—the researchers maintained robust ferroelectric performance while drastically reducing device size.

Key to the success was a post-heat treatment of the bottom platinum electrode at 840°C, which improved its crystal orientation and enhanced polarization switching in the ultrathin films. This process ensures that the scaled-down capacitors remain compatible with semiconductor integration, enabling on-chip embedding alongside logic circuits.

The breakthrough lays the groundwork for compact ferroelectric memories, such as FeRAM and ferroelectric tunnel junctions, for future IoT and mobile electronics. By further exploring alternative electrode materials and processing techniques, the team aims to create even more durable, energy-efficient, and miniaturized on-chip memory devices.

Full details on the research are available here.

Institute of Science Tokyo 

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