Performance improvement of Hf0.45Zr0.55O x ferroelectric field effect transistor memory with ultrathin Al–O bonds-modified InO x channels

Abstract

Ferroelectric field effect transistor (FeFET) memories with hafnium zirconium oxide (HZO) ferroelectric gate dielectric and ultrathin InO x channel exhibit promising applicability in monolithic three-dimensional (M3D) integrated chips. However, the inferior stability of the devices severely limits their applications. In this work, we studied the effect of single cycle of atomic-layer-deposited Al–O bonds repeatedly embedded into an ultrathin InO x channel (∼2.8 nm) on the Hf0.45Zr0.55O x FeFET memory performance. Compared to the pure InO x channel, three cycles of Al–O bonds modified InO x channel (IAO-3) generates a much larger memory window (i.e. drain current ratio between the programmed and erased devices) under the same program conditions (+5.5 V/500 ns), especially after post-annealing at 325 °C for 180 s in O2 (1238 versus 317). Meanwhile, the annealed IAO-3 FeFET memory also shows quite stable data retention up to 104 s, and much more robust program/erase stabilities till 105 cycles. This is because the modification of strong Al–O bonds stabilizes the oxygen vacancies and reduces the bulk trap density in the channel. Furthermore, it is indicated that the program and erase efficiencies increase gradually with reducing the channel length of the memory device. By demonstrating markedly improved performance of the HZO FeFET memory with the ultrathin IAO-3 channel, this work provides a promising device for M3D integratable logic and memory convergent systems.