A novel methodology for altering the amount and/or nature of post-anneal disorder in SIMOX substrates has been investigated. A pre-anneal, secondary Si-ion implant (with an ion range less than that of the primary O-ion implant) is shown to effectively getter Si interstitials to the near-surface region during annealing. As a consequence, post-anneal disorder at the front. Si/SiO2 interface is significantly reduced. Alternatively, a Si-ion implant with an ion range greater than that of the O-ion implant can alter the post-anneal disorder at the back Si/SiO2 interface.