High performance La-doped HZO based ferroelectric capacitors by interfacial engineering
M. Popovici, Jasper Bizindavyi, Paola Favia, Sergiu Clima, Md Nur K. Alam, R.K. Ramachandran, A. Walke, Umberto Celano, A. Leonhardt, S. Mukherjee, Olivier Richard, A. Illiberi, Michael Givens, Romain Delhougne, Jan Van Houdt, Gouri Sankar Kar
Abstract
We show how interfacial oxide engineering in La-doped hafnium zirconate (HZO) ferroelectric (FE) capacitor stacks can be used to significantly improve the ferroelectric response and remnant polarization (P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</inf> ) of the HZO. This is achieved by incorporating either a 1 nm TiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> seed and/or 2 nm Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> cap layer in a bilayer (BL) and/or trilayer (TL) configuration with TiN top and bottom electrodes. We show how the Nb <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> cap is able to facilitate the transition from (anti-FE) tetragonal into (FE) orthorhombic phase by injecting oxygen in the HZO and find that the TiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> seed layer favorably improves the grain orientation inside the HZO, resulting in a higher 2P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</inf> and reduced wake-up. Finally, depending on the precursors of Hf and Zr that are used, we demonstrate both trilayer devices with an endurance of up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cycles with a final 2P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</inf> of ~30μC/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 1.8 MV/cm or devices with a record high 2P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R,max</inf> of 66.5 μ C/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> after 3× 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> cycles at 3 MV/cm.