Enhanced phonon-energy coupling: Dramatic reduction of leakage current of silicon oxide

We study in detail a newly discovered effect, phonon-energy-coupling enhancement (PECE) effect, produced by rapid thermal processing (RTP). It includes two aspects: (1) Strengthening Si-D bonds and Si-O bonds and (2) Change of energy band structure and effective mass due to thermal shock. It is shown that not only Si-D bonds but also Si-O bonds have been strengthened dramatically, leading to enhancement of robustness of the oxide structure and the oxide/Si interface. For thick oxides (>3 nm), the gate leakage current has been reduced by two orders of magnitude and the breakdown voltage has been improved by ∼30% due to phonon-energy coupling. For ultrathin oxides (2.2 nm), the direct tunneling current has been reduced by five orders of magnitude, equivalent to that of HfO₂, probably due to the increased effective mass and barrier height.