Space charge effects in SIMOX buried oxides

X-ray induced charge trapping in SIMOX buried oxides is investigated. Dose and applied field dependence is modeled by taking into account internal space charge effects due to hole and electron trapping. Oxide trapped charge measured via etch-back experiments on SIMOX MOS capacitor structures reveals a good agreement with numerical simulations. However, the model is no longer valid when applied to previous data obtained on irradiated back-channel transistors where enhanced electron trapping had been observed. Possible implication of this discrepancy on the SIMOX electron trap nature is discussed