Negative dilatation (shrinkage) induced by 10‐keV electron bombardment of SiO2films thermally grown on Si has been studied. Measured deflection changes in continuous SiO2bridges etched following irradiation showed a maximum shrinkage of [inverted lazy s] 0.8%, which occurred at 0.2 C/cm2, followed by a slight expansion, and subsequent saturation at higher exposures. Exposures up to 3 C/cm2were utilized. Isochronal annealing studies show the activation energy for recovery to be approximately 1 eV with 2% recovery occurring in 1 h at 400°C.