Mechanisms of defect formation and growth in oxygen implanted SOI material during thermal ramping and isothermal annealing.

To understand the formation and evolution of precipitates and defects the authors have studied structural changes in SIMOX (separation by implantation of oxygen) material annealed at temperatures covering the range from lower temperature thermal ramping through high-temperature isothermal annealing. Precipitates and defects were studied with electron microscopy techniques, including high-resolution imaging. Samples annealed for 2 h at lower temperatures from 700°C to 750°C show no structural changes compared to as-implanted material. Samples annealed at intermediate temperatures from 800°C, to 950°C show a series of unusual structural changes which result in the formation of stacking faults. Initially, at 800°C and 850°C small, 3- to 5-nm precipitates form very close (within 10 to 20 nm) to the wafer surface and generate one or two short {111} stacking faults that run only to the wafer surface. At 900°C and 950°C, the presence of the short stacking faults near the surface enhances oxygen diffusion and causes near-surface precipitates to grow and form new stacking faults that extend downward through the superficial layer. High-temperature annealing, at 1100°C and 1250°C, causes precipitate dissolution and stacking fault stabilization.