From planar to vertical capacitors: A step towards ferroelectric V-FeFET integration

Ferroelectric hafnium oxide (HfO 2 )attracted a lot of interests since its discovery in 2007. Its scalability and CMOS compatibility are two advantages over conventional ferroelectric materials, favoring new device integration. Doped ferroelectric HfO 2 Metal/Insulator/Metal capacitors have been widely studied for DRAM and FeFET applications. Silicon electrodes have not been discussed in much detail so far, though it provides an input for vertical ferroelectric FET (V-FeFET), based on Flash NAND architecture. In this work, planar and vertical capacitors are presented using silicon as electrodes and aluminum doped HfO 2 as ferroelectric material. The process of the vertical integration is described. Polarization-Voltage measurements show a steep ferroelectric hysteresis loop for the planar as well as vertical capacitors. This demonstrates the conservation of the ferroelectric properties of the dielectric after deposition on an etched vertical wall and lays the first stone toward V-FeFET integration.