True oxide electron beam induced current for low-voltage imaging of local defects in very thin silicon dioxide films

A new low-voltage contrast mechanism due to electron hole pairs generated in the oxide by an electron beam was observed at an electric field lower than 3.5 MV/cm in addition to the tunneling current microscopy (TCM) contrast mechanism at electric fields higher than 3.5 MV/cm. The new contrast mechanism is opposite in sign to the TCM contrast mechanism. Good contrast can be obtained at an electric field as low as 2.4 MV/cm, which is two to three times smaller than that needed for TCM contrast. Potential applications include large area imaging and quantitative imaging of oxide defects.