Characterization of electron beam induced modification of thermally grown SiO2

We used local probe techniques to characterize electron beam ~e-beam! induced changes in thin oxides on silicon. Primary effects of the 1 nm wide, 300 keV e beam included the formation of positive charges trapped in the SiO2 , physical restructuring in the oxide, and deposition of carbonaceous compounds. Charges remained stable in thicker oxides ~460 nm! and appeared as changes in the contact potential or microwave response with widths down to 100 nm. In thinner oxides ~20 nm! the amount of charge was smaller and less stable; below 7 nm no charge was detected. Physical changes in the oxide, evident as a swelling of irradiated areas, accounted for the etching selectivity of these regions. © 1995 American Institute of Physics.