First Demonstration of Annealing-Free Top Gate La:HZO-IGZO FeFET with Record Memory Window and Endurance

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
r
of 30 μC/cm
²
with a low thermal budget of 300
^o
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
¹⁰
while maintaining large MW of 1.9 V and 10
⁸
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.