Characterization of HfSiON gate dielectrics using monoenergetic positron beams.

The impact of nitridation on open volumes in thin HfSiO_x films fabricated on Si substrates by atomic layer deposition was studied using monoenergetic positron beams. For HfSiO_x, positrons were found to annihilate from the trapped state due to open volumes which exist intrinsically in an amorphous structure. After plasma nitridation, the size of open volumes decreased at a nitrogen concentration of about 20 at. %. An expansion of open volumes, however, was observed after postnitridation annealing (PNA) (1050 °C, 5 s). We found that the size of open volumes increased with increasing nitrogen concentration in HfSiO_x. The change in the size of open volumes was attributed to the trapping of nitrogen by open volumes, and an incorporation of nitrogen into the amorphous matrix of HfSiO_x during PNA. We also examined the role of nitrogen in HfSiO_x using x-ray photoelectron spectroscopy and first principles calculations. [ABSTRACT FROM AUTHOR]