Gate dielectric monitoring using non-contact electrical characterization

Reduction of gate oxide thicknesses to the tunnelable range as well as the anticipated introduction of alternative gate dielectric materials create new challenges regarding monitoring of gate insulation processes. In this paper methodologies applied in gate oxide characterization are considered and advantages of non-contact methods are emphasized. More specifically, the Surface Charge Profiling (SCP) method, which is particularly well suited for this application is discussed. This method allows measurement of the charge density without any bias on the oxide, and hence, without any current flow across the oxide. Therefore, measurements of surface/oxide charge density as well surface recombination lifetime can be carried on oxides in which charge measurement using other methods would be prevented due to significant current. This capability of the SCP method is demonstrated using experimental results.