The effects of TCA incorporation during annealing process on the SIMOX quality is studied. Silicon wafers are implanted with heavy dose of oxygen ions, and are annealed at $1300^{circ}C$ for 4 hours. The annealing process is splitted into three conditions due to some differences of low temperature preliminary annealing step which are without pre-annealing step. The specimens are analyzed by several methods, such as AES, XTEM, and TRXFA. TCA incorporation during pre-annealing step is effective in dislocation density reduction and heavy metal content reduction.