ions with different energies and doses were implanted into SIMOX (separated by implantation of oxygen) materials to improve their irradiation hardness characteristics. Capacitors were fabricated on the SIMOX material after removing the top silicon layer. The high-frequency C-V characteristics of the capacitors after irradiation with -rays were investigated. It is found that the process of implantation can effectively improve the total-dose irradiation hardness of the buried oxide (BOX) layer of the SIMOX materials. In addition, with the change of dose and energy of the implantation, the distribution of F in the SIMOX material was also changed; in particular, for the dose of and 90 keV implantation, a nearly uniform fluorine doping is produced in the BOX layer upon annealing.