GENERATION AND ANNIHILATION OF THERMAL DONORS IN SILICON THIN-FILMS FORMED BY OXYGEN IMPLANTATION

Oxygen-induced thermal donors are undesirable in silicon substrates for integrated circuit technology. In order to study the generation and annihilation of electrically active thermal donors in silicon films synthesized by oxygen implantation (SIMOX), conductivity and Hall measurements were carried out on several samples. After the oxygen implantation, these samples were first anneaed at high temperature for 6 h and then reannealed at 450, 650 and 850°C for various periods of time. The thermal donor concentrations, mobilities and ionization energies were measured, by Hall effect, between 30 and 400 K. It was found that, by increasing the donor concentration, species with lower ionization energies are formed at the expense of those having higher ionization energies. The behaviour of oxygen donors in SIMOX is governed by various metastable species (including compensation centres) and appears to be even more complex than in bulk silicon. © 1990.