Examination of the charge storage of Si- and Ge nanoclusters in SiO2 films by scanning probe techniques

Embedded Si or Ge nanoclusters in SiO2 films might be a future alternative to conventional floating gate memories. Si or Ge implanted 20nm SiO2 layers were annealed to generate nanoclusters with sizes of 3-4 nm. The charge storage of the implanted layers was studied by scanning capacitance microscopy (SCM) and electrostatic force microscopy (EFM). Local charge injections were accomplished by a biased conductive tip.
The amount of the injected charge was estimated from the shifts of the local dC/dV curves acquired with scanning capacitance spectroscopy (SCS). The SCS data were compared with CV-measurements on planar MOS structures. The decay of the SCM- and EFM-contrasts was monitored and the retention time was determined.