Influence of the Silicon Dioxide Layer Thickness on Electroforming in Open TiN–SiO2–W Sandwiches

Abstract

Based on experimental data for electroforming in open TiN–SiO₂–W sandwich structures (the end face of d = 10–30-nm-thick SiO₂ films exposed to vacuum served as an insulating trench), it has been shown that the voltage at which conducive particles (CPs) arise (i.e., the electroforming onset voltage) changes insignificantly with decreasing thickness d. The electroforming process is initiated by a voltage with a threshold near 8.5 V, rather than by electric field strength. This value far exceeds the CP formation voltage threshold when already formed structures switch over (3–4 V). This points to the existence of two nonthermal mechanisms that activate CP formation under electron impact. In the case of electroforming, this is dissociative attachment of an electron, which causes an oxygen atom to escape into vacuum and, hence, an increase in the silicon atom concentration on the surface of the insulating trench. In the case of switching, this is a change in the molecular state of oxygen (or hydrogen) on the surface.