Effects of oxidation process on interface roughness of gate oxides on silicon: X-ray reflectivity study

Abstract

We report on the effects of the wet and dry oxidation processes on the interfacial roughness and time dependent dielectric breakdown (TDDB) characteristics of the poly-Si/SiO2/Si(100) trilayer. The interface roughness of the oxide layers buried under a thick poly-Si electrode has been investigated using an x-ray reflectivity technique. Analysis of x-ray reflectivity data for the trilayer samples and for a bare oxide film shows that interface roughness of poly-Si electrode/SiO2 interfaces depends on oxidation process while oxide layers have smooth SiO2/Si-subtstrate interfaces. TDDB of the SiO2 layer has also been observed to depend on the oxidation process, indicating that the interface roughness is a crucial factor affecting the TDDB characteristics. The wet oxidized SiO2 film is more stable to dielectric breakdown and has smoother interfaces than the dry oxidized sample.