Formation of high density TiN nanocrystals and its application in non-volatile memories

Authors：Li Xue Lin^*; Feng Shun Shan; Chen Guo Guang

Source：Chinese Physics B, 2008, 17(3): 1070-1077.

• TiN nanocrystal
• size
• density
• non-volatile memory application

Non-volatile memory based on TiN nanocrystal (TiN-NC) charge storage nodes embedded in SiO(2) has been fabricated and its electrical properties have been measured. It was found that the density and size distribution of TiN-NCs can be controlled by annealing temperature. The formation of well separated crystalline TiN nano-dots with an average size of 5 nm is confirmed by transmission electron microscopy and x-ray diffraction. x-ray photoelectron spectroscopy confirms the existence of a transition layer of TiN(x)O(y)/SiON oxide between TiN-NC and SiO(2), which reduces the barrier height of tunnel oxide and thereby enhances programming/erasing speed. The memory device shows a memory window of 2.5V and an endurance cycle throughout 10(5). Its charging mechanism, which is interpreted from the analysis of programming speed (dV(th)/dt) and the gate leakage versus voltage characteristics (I(g) vs V(g)), has been explained by direct tunnelling for tunnel oxide and Fowler-Nordheim tunnelling for control oxide at programming voltages lower than 9V, and by Fowler-Nordheim tunnelling for both the oxides at programming voltages higher than 9 V.

• Institution
  中北大学; 北京理工大学