THE LOW ELECTRIC-FIELD CONDUCTION MECHANISM OF SILICON-OXIDE SILICON-NITRIDE SILICON-OXIDE INTERPOLY-SI DIELECTRICS

A model for the leakage current of silicon oxide-silicon nitride-silic on oxide (ONO) dielectrics at low electric fields (similar or equal to 2 MV/cm) was successfully developed. It is proposed that two transiti on mechanisms occur simultaneously. One is the detrapping of electrons from the silicon dangling bond in amorphous silicon nitride (SiN), wh ich corresponds with the transition of dangling bonds among three poss ible charge states. The second is the direct tunneling of the detrappe d electrons from the SiN to the gate through the thin silicon oxide. B oth the location and the energy levels of the defect state are taken i nto account. The energy level, and the intrinsic time constant of the Si dangling bond and the uniform trap density in SiN, can be obtained by comparing the experimental. results of the ONO discharge current wi th the calculated ones based on the above model. It can be found that the energy levels for negatively charged and neutral Si dangling bonds (E(-) and E(0)), with respect to the SiN conduction band, are 1.2 and 2.0 eV, respectively, the intrinsic time constants t(-) and t(0) are 1.0 X 10(-14) and 4.0 X 10(-13) s, respectively, and the uniform trap density is 4.0 X 10(19)/cm(3). From the energy level difference betwee n E(-) and E(0), we can conclude that the effective correlation energy of the Si dangling bonds in SiN is 0.8 eV, which is consistent with R obertson's results based on a tight binding calculation. (C) 1995 Amer ican Institute of Physics.