MAPPING OF MOBILE CHARGES ON INSULATOR SURFACES WITH THE ELECTROSTATIC FORCE MICROSCOPE

Migration of surface ions in lateral fields on insulator surfaces may modify the electrical characteristics of underlying semiconductor structures causing device instabilities. A high sensitivity electrostatic force microscope is used to image the movement and spatial distribution of surface ions on Si3N4. Mobile surface ions are distributed by the fringing fields of a p-n junction and an open-gate field-effect transistor. The surface charge distribution and topography are imaged simultaneously on a micrometer scale.