Silicon-on-insulator (SOI) material fabricated by oxygen implantation (SIMOX) is being used for radiation hard, higher speed, and higher temperature integrated circuits. The microstructural evolution of oxides during implantation, thermal ramping, and annealing plays a crucial role in development of the structure of the top Si layer and of the buried oxide layer. To control the micro-structure of the oxides and silicon it is necessary to understand the effect of processing conditions on the mechanisms of oxide formation and evolution. These processing conditions include: implantation temperature, energy, and dose; thermal ramping rate; and annealing time, temperature, and atmosphere. Numerous questions still remain on the effects of processing conditions and include: formation and growth of the buried oxide; formation and evolution of oxygen bubbles in the top silicon layer; and precipitate evolution and elimination during ramping and annealing. The goal of this paper is to summarize recent work on the effects of processing conditions on oxide evolution and to present new results on; effects of implantation conditions on buried oxide formation, effects of ramping conditions on oxygen bubble evolution and defect formation, and effects of annealing conditions on structure of the buried oxide and its interfaces.