Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) have been employed for the investigation of trap creation in ultrathin SiO2 films on an atomic scale. Bright spots created by electron injection using STM tips were observed in STM images. The density of bright spots depends on the injection voltage and temperature. Comparing STS spectra obtained from electron-injected SiO2 films with those from a fresh film, we have found that the bright spots are related to positively charged traps in the SiO2 films and caused a band bending near the Si/SiO2 interface.