Flexible Ferroelectric Memory Using Non-Adhesive Transfer Layer

We present an environmentally-friendly water-based transfer approach to achieve inorganic ferroelectric memory on ultrathin flexible substrates. The device fabrication process is first performed on a gold-coated silicon substrate, including high-temperature (500 °C) steps which are not compatible with flexible substrates. We then coat the devices with the polyimide and release the structure from the rigid substrate, thus enabling ferroelectric hafnium-zirconium-oxide (HZO) devices on an ultrathin flexible substrate. As a proof-of-concept, we demonstrate 10 nm thin HZO capacitors with good ferroelectric switching, having polarization <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\sim 4\, \mu \mathrm{C} / \text{cm}^2$</tex> and endurance ∼10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup>. Our devices also show no degradation up to 125 °C operating temperature and under bending radius of 3 mm.