Analysis of gate oxide damage by ultraviolet light during oxide deposition in high density plasma

The UV-induced damages to the gate oxide in a commercially available high-density-plasma dielectric oxide deposition system for the ultra-large integrated circuit fabrication process were analyzed systematically using the metal-oxide-semiconductor capacitors with different antenna ratio. UV-induced damages exclusively in the gate oxide were evaluated by depositing 2500 Å thick oxide layer only once and twice on the two wafers separately and comparing the two results: the deposition of the oxide layer of only 2500 Å did not cause any degradation in the SPDM wafer while the double deposition revealed antenna-ratio dependent shift of the breakdown voltage. The deviation of the values of breakdown voltage of the damaged wafer from its normal ones was found mainly at the center of the wafer where the intensity of the UV light is generally higher in the inductively coupled plasma source.