First demonstration of vertically stacked ferroelectric Al doped HfO2 devices for NAND applications

A 3D ferroelectric Al doped HfO2 device for NAND applications was fabricated for the first time. The polysilicon (poly-Si) channel, whose diameter ranges from 60 to 200 nm, was highly doped for a better understanding of the ferroelectric properties. Electrical results confirmed the presence of the ferroelectric phase with a coercive voltage (2Vc) of 6 V extracted from the hysteresis loop. The drain anneal was found to have a significant impact on HfO2 properties and needs to be reduced to preserve the ferroelectricity. Finally, reliability investigations showed an estimated time to failure of more than 10 years at 85 °C. This study lays the foundation for the fabrication of 3D ferroelectric field effect transistors (FeFET).