Nanocrystal Non-volatile Memory Devices

Kedar Patel

Liu et al (April 2006)Blauwe (Trans. on Nanotechnology, March 2002)Lin et al (TED, April 2006)

NV Memory Device

ProgrammingChannel Hot Electron injection or Fowler-Nordheim tunneling into poly or nc-Si

EraseFowler Nordheim tunneling to substrate or source

Quantum Scale!For 50nm x 50nm memory cell (transistor) and 1012 cm-

2 nanocrystal density:

25 nc per cell

For 32nm x 32nm memory cell (transistor) and 1012 cm-

2 nanocrystal density:

10 nc per cell

Fabrication• Excess Si-Precipitation

– Few 1-10keV, 1016 cm-2 Si implanted in SiO2 + 1000C N2 anneal

3-10nm nc-Si precipitates, ~1012 cm-2

• Aerosol Deposition– Pyrolysis of Silane (SiH4) at 950C

• Direct Deposition– LPCVD of Poly-Si; stop shortly after nucleation of

sites before a continuous film is formed

PbSe or Co Nanocrystals

Tang et al (TED, March 2007)