Effect of SiO_2 Tunnel Oxide Thickness on Electron Tunneling Mechanism in Si Nanocrystal Dots Floating-Gate Memories

摘要

The effect of tunnel oxide thickness on the charging/discharging mechanism and data retention of Si nanocrystal dot floating-gate devices was studied. The key point here is the difference in tunnel oxide thickness. Other parameters that can affect memory properties were carefully controlled. The mechanism of electron discharging was discussed on the basis of the difference in tunnel SiO_2 thickness. Direct tunneling was found to dominate in the 3- and 5-nm-thick SiO_2 tunnel oxides. However, Fowler-Nordheim (FN) tunneling affects the electron discharging characteristics of a thicker SiO_2 tunnel oxide. It was found that memory properties also strongly depend on tunnel oxide thickness.