Size and density controlled metal nanocluster embedded metal-oxide-semiconductor structure for memory applications

TL;DR

This study demonstrates how controlling size and density of metal nanoclusters embedded in a MOS structure enhances non-volatile memory performance, with smaller clusters improving charge storage and retention.

Contribution

It introduces a fabrication method for metal nanoclusters with independent control over size and density, optimizing memory device characteristics without annealing.

Findings

Maximum hysteresis at a cluster density of 1×10^{11} cm^{-2}

Smaller nanoclusters (1.5 nm) improve charge storage and retention

Device performance peaks with nanoclusters of 1.5 nm diameter

Abstract

Metal-nanoclusters (NC), deposited by magnetron-based nanocluster source coupled with quadrupole mass filter (QMF) assembly having independent control over its size and density, are used in fabricating NC-based non-volatile memory (NVM) devices. The effect of diameter and density on the NVM charge storage characteristics are presented where Ag is used as the metal NC. The Ag-NC, sandwiched between HfO$_2$ tunnel and control oxides, is deposited by using the combination of the above two instruments. No annealing is performed at any stage of the device fabrication. The largest hysteresis loop area in the capacitance-voltage ($C-V$) characteristics of metal-oxide-semiconductor (MOS) characteristics is observed for a cluster density of 1 $\times$ 10$^{11}$ cm$^{-2}$. Further, an NC size dependent hysteresis loop area is observed with the MOS devices where the NC diameter is varied from 3 to 1.5 nm keeping the NC density at 1 $\times$ 10$^{11}$ cm$^{-2}$. The device performance is found to be improved with a reduction of the NC size and shows its best with the NC diameter of 1.5 nm. The storage time of the NVM devices also increases with the decrease in the NC diameter and exhibits their best performances for the NCs with a diameter of 1.5 nm.