The influence of the rapid thermal annealing (RTA) in vacuum on the properties of thermally grown SiO2 has been investigated by means of high field Fowler-Nordheim tunneling injection. The results indicate that the RTA process anneals the original electron traps existing in as-grown oxides while also introducing positive charge manifested as electron traps. The dependence of these charges on the annealing temperature (1073-1473 K) is a strong function of the technological history of the samples.