Effects of strained layer near SiO2-Si interface on electrical characteristics of ultrathin gate oxides

ltrathin gate oxides formed by different process technologies are investigated in detail. The following important evidence is found: the discrepant result on the two time-dependent dielectric breakdown (TDDB) lifetime measurements, the constant-current stress, and the constant-voltage stress. The discrepancy is due mainly to the difference in the oxide leakage characteristics. Apparent changes in the activation energy and the defect generation rate during the TDDB testing are also experimentally observed for the two oxides formed by different process technologies. From the analysis based on the x-ray photoelectron spectroscopy by means of the oxide etch by dilute HF and the Fourier-transform infrared attenuated total reflection method, we consider that the above phenomena are induced by the difference in the built-in compressive strain of the Si-O network near the SiO2 and Si interface. (C) 2000 American Institute of Physics. [S0021-8979(00)06904-8].