First Demonstration of Annealing-Free Top Gate La:HZO-IGZO FeFET with Record Memory Window and Endurance
Min Zeng, Qianlan Hu, Qijun Li, Honggang Liu, Shiwei Yan, Chengru Gu, Wenjie Zhao, Ru Huang, Yanqing Wu
Abstract
Ferroelectric films with low process temperature (below 400 °C) are desirable for top gate FeFET toward back-end-of-line applications such as monolithic 3D integration. In this work, we demonstrate annealing-free Metal-Ferroelectric-Metal (MFM) with record 2P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> of 30 μC/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with a low thermal budget of 300 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> C growth temperature based on La-doping HZO for the first time. Grazing-incidence X-ray diffraction (GIXRD) results show that the high fraction of 57% for the ferroelectric orthorhombic phase (o-phase) in La:HZO films can be obtained, 1.6 times higher than the 35% o-phase of the nondoped HZO film. Single grain over 20 nm of orthorhombic phase in La:HZO films is observed by high-resolution transmission electron microscopy (HRTEM). Moreover, Metal-Ferroelectric-Semiconductor-Metal (MFSM) capacitors can also exhibit considerable switching polarization and good endurance by replacing the commonly used tungsten electrode. Furthermore, La:HZO-IGZO based top-gate FeFET with a channel length down to 40 nm is demonstrated also using an annealing-free fabrication process, exhibiting record-large memory windows (MW) of 3.3 V, nearly 2 times higher than that of HZO. Meanwhile, record-high endurance of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> while maintaining large MW of 1.9 V and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> with MW of 3.1 V can also be demonstrated, showing the great potential of La:HZO for highly reliable ferroelectric memories toward BEOL applications.