Improvement in radiation hardness of gate oxides in metal–oxide semiconductor devices by repeated rapid thermal oxidations in N2O

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Abstract
Instead of using the conventional one‐time N2O oxidation of silicon, repeated N2O rapid thermal oxidations (RNRTO) is proposed as a new gate oxide preparation method. The radiation hardness of metal–oxide semiconductor (MOS) capacitors with RNRTO oxide is found to be better than that with the conventional one‐time N2O‐grown oxide. The nitrogen content at the SiO2/Si interface as determined by secondary ion mass spectroscopy (SIMS) is constant for all the RNRTO samples but the thickness of the nitrogen‐rich interfacial layer increases as the number of RNRTO increases. The less strain gradient caused by this increasing nitrogen‐rich interfacial layer thickness is the main cause of improving the radiation hardness of the MOS capacitors.