Visualization of electrons localized in metal-oxide-nitride-oxide- semiconductor flash memory thin gate films by detecting high-order nonlinear permittivity using scanning nonlinear dielectric microscopy

Charge accumulation in semiconductor devices was investigated by using scanning nonlinear dielectric microscopy (SNDM) to detect a high-order nonlinear permittivity (ε3333). This higher-order SNDM has a much higher resolution than conventional SNDM that is used to measure the lowestorder nonlinear permittivity (ε333). It enabled us to visualize highly resolved charge patterns stored in SiO ₂-SiN-SiO ₂ (ONO) films of downsized metal-ONO-semiconductor (MONOS) flash memory with a high contrast. ε3333 images of the stored electron distributions in ONO films of n-MONOS exhibited the highest contrast reported by detecting ε333.