Ferroelectric Transistor With Grooved Structure for Reliable Multi-Level Characteristics

Ferroelectric transistors that use hafnia-based ferroelectric materials are considered as a promising candidate for next-generation memory devices due to their fast operation speed, low power consumption, and high scalability. However, as the polarization switching of ferroelectric materials mostly occurs near the coercive electric field, ferroelectric transistors exhibit non-linear switching characteristics. Thus, precise tuning of voltage pulses is required to achieve multi-level characteristics, which requires finely controlled voltage generators. This work demonstrates a ferroelectric transistor with a grooved ferroelectric layer that enables reliable multi-level operation. The grooved ferroelectric layer exhibits multiple coercive electric fields, resulting in a broadened program window. We show that by implementing the grooved ferroelectric layer, multi-level operation can be achieved using voltage pulses with a larger window, leading to reliable multi-level operation with small distributions. This work provides promising prospects for next-generation, reliable ferroelectric memory.