Ferroelectric Thickness Dependent Domain Interactions in FEFETs for Memory and Logic: A Phase-field Model based Analysis
Atanu Saha, Mengwei Si, Kai Ni, Suman Datta, P. D. Ye, Sumeet K. Gupta
Abstract
We present a phase-field simulation framework for ferroelectric (FE)-FET which captures multi-domain effects by self-consistently solving 2D time-dependent Ginzburg-Landau (TDGL), Poisson's, and semiconductor charge/transport equations. Using our phase-field model and experiments, we analyze electrostatics-driven multi-domain formation and voltage-induced polarization (P) switching for different FE thickness (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> ). We show that for T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> = 5nm - 10 nm, FEFETs exhibit multi-level memory functionality; while for T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> = 1.5nm - 3 nm, FEFETs can serve as non-hysteretic switches with enhanced gate control. Our results signify that as T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> is reduced from 10nm to 5nm, denser domain patterns emerge in FE, and the dominant P-switching mechanism changes from nucleation to domain-wall motion based leading to a decreased memory window with T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> scaling. Moreover, as T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FE</sub> is scaled further from 3nm to 1.5nm, effective permittivity of the gate stack increases due to multi-domain electrostatic interactions.