Charge-trapping properties of poly-silicon oxides by rapid thermal N2O process

The polyoxide with nitrogen incorporation by RTN2O process can obtain smoother interface of the polyoxide/polysilicon, thus improving the characteristics of polyoxides. However, too much nitrogen does not improve, instead, degrades, the quality of the polyoxide and to induce thickness non-uniformity. It can be found that initial hole-trapping phenomenon was observed in the polyoxides grown by rapid thermal N2O oxidation process and the higher the growth temperature is, the larger the hole-trapping rate is. The larger hole-trapping is due to more excessive nitrogen release in short time at the polyoxide/polysilicon interface at high temperature oxidation, which may induce large undulations at the Si/SiO2 interface and result in localized high electric fields to obtain smaller Qbds. However, the charge-trapping properties can be improved by the N2O-annealed process at proper temperature due to proper amount of nitrogen incorporated into the polyoxide and piled up at the interface.