Interfacial reaction in the sputter-deposited SiO2/Ti0.1W0.9 antifuse system

The effects of annealing temperature on the interfacial reactions and the antifuse I-V characteristics of ultra thin SiO2 layer deposited on Ti0.1W0.9 substrate were investigated. The interfacial reactions were analyzed using x-ray photoelectron spectroscopy and Auger electron spectroscopy with the sample which is in situ annealed under ultra high vacuum or ex situ annealed in a nitrogen atmosphere. The surface of the Ti0.1W0.9 substrate was oxidized during sputter deposition of SiO2 layer. Ti, W oxides consist of Ti2O3 (Ti3O5), TiO2, WO2, and WO3. The WO3 and Ti2O3 decomposed into metallic W and Ti at 400 and 500 °C, respectively. The breakdown voltage of the antifuse decreased as the annealing temperature increased, due to the thinning of dielectric layer resulted from the decomposition of Ti, W oxides and the formation of metallic W and Ti. Annealing at 600 °C caused the reaction between metallic (Ti,W) and SiO2 layer and formed elemental silicon in the dielectric layer, where SiO2 layer completely lost its dielectric property. The breakdown of dielectric property might form a metallic channel in the SiO2 film, which mainly contains metallic W, Ti, and Si.