Surface cleaning effect on dielectric integrity for ultrathin oxynitrides grown in N2O

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Abstract
In this study, we developed a wafer‐cleaning procedure for ultrathin dielectric growth. This involves a modified RCA clean, a dilute‐HF dip and a subsequent immersion in methanol/HF solution. Ultrathin (≊42 Å) oxynitride films were grown in pure N2O using this new cleaning procedure and some other schemes to investigate the effects of surface preparation on dielectric integrity. Devices fabricated by this new cleaning procedure were found to exhibit the lowest leakage current level and the best breakdown performance among all samples. The variation in the current‐voltage characteristics across a 4‐in. wafer was also minimized by this two‐step dipping process. The results suggest that the new cleaning procedure is desirable to yield high‐quality ultrathin dielectrics.