A New Surface Potential and Physics Based Compact Model for a-IGZO TFTs at Multinanoscale for High Retention and Low-Power DRAM Application

Abstract

Extremely scaled amorphous In-Ga-Zn-O thin film transistors (a-IGZO TFTs) can meet the increasing demand of high-density and low-power in DRAM design. Traditional percolation mechanism (PM) in a-IGZO TFTs compact model is done for infinite disordered systems, leading to error for scaled devices. To address this, a surface potential and physics-based compact model is proposed accounting for the effect of scaling on the device and material properties. Particularly, it is achieved with finite-size corrected hopping and percolation models derived using connected subnetworks. Multi-channel percolation (MCP) determines the performance for aggressively scaled device (e.g., sub-12nm) and exhibits a path-limited feature and power-law T-dependence. Final projections of current and capacitance characteristics are in excellent agreement with experiments, considering extreme-scaling induced severe short channel and contact effects. As the fabrication variability is significant in integrated circuits, we have explored statistical effects on subthreshold properties. Retention and statistical performances of a 2T0C configuration were subsequently evaluated and indicate a great potential for a-IGZO-based 3D-DRAM memories.