REACTIVE ION ETCHING INDUCED DAMAGE TO SIO2 AND SIO2-SI INTERFACES IN POLYCRYSTALLINE SI OVERETECH

The effects of reactive ion etching on the properties Of SiO2 and SiO2-Si interfaces have been examined for the case of polycrystalline Si overetch exposures. HBr/Cl2-based polycrystalline Si etch chemistry was used and damage effects for thermally grown oxides with various thicknesses were determined as a function of the overetch exposure times. A large amount of charge was found from capacitance-voltage measurements to be created in the plasma exposed oxides. This charge density increased with increasing overetch time and decreasing initial oxide thickness. Ramp voltage and constant current stress tests were both used to determine the dielectric strength and long-term reliability of these same plasma exposed oxides. A very significant degradation of charge to breakdown was found for the plasma exposed oxides as compared to unexposed control oxides.