Defect States Induced by Rapid Thermal Annealing in Virgin or Implanted Czochralski-Grown Silicon

Defect state generation in either virgin or implanted CZ silicon has been investigated by means of capacitance transient spectroscopy (DLTS) after rapid thermal annealing (RTA), using an incoherent light furnace and variable cycle parameters. No electron traps were dectected with gold Schottky contacts made on virgin phosporous-doped silicon annealed for 5 sec at any temperature. On the otherhand 3 hole trap levels H1(0.45 eV), H2(0.29 eV) and H3(0.31 eV) have been observed in boron-doped silicon (Al Schottky contacts) after a 5 sec temperature plateau between 850 and 1050°C. Peak concentrations ranging from 1013 to 1014 cm−3 were measured after annealing at 1000°C for the three hole traps. By increasing the plateau duration up to 20 sec hole traps were no longer detected in boron-doped silicon. Furthermore in As+ or PF5+-implanted and rapidly annealed N+/P junctions the H3(0.31 eV) level was replaced by another hole trap H4(0.4 eV), which appeared within specific conditions (RTA parameters, implant dose and species). Moreover an electron trap E(0.55 eV) was only detected in the high dose As+-implanted junctions after annealing for 10 sec at 1100°C. The probable metallic origin of the observed defect states and the RTA parameter dependence of the hole trap concentrations suggest gettering and trapping in interstitial sites as possible mechanisms involved in RTA.