Mechanism of E' Center Generation in SiO2 Film by Ion and Neutral Beam Bombardment

The radiation damage in SiO2 films thermally grown on silicon and bombarded by ion and neutral beams has been studied by electron spin resonance (ESR). It is found that the E' center generation yield is much higher for ion bombardment than for neutral bombardment in spite of the same kinds of atoms and the same incident energy. The generation yield of ion-induced E' centers depends on the incident energy and ionization energy of the parent atom. On the other hand, for neutral bombardment, it depends only on the incident energy. These results indicate that the neutral-induced E' centers are created by bond breaking due to a collision cascade. However, ion-induced E' centers are generated by both collision cascades and carriers (electrons and holes) induced in the SiO2 film by ion neutralization.