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Metallic Ru and Hf-based dielectrics such as HfO 2 , HfSiO x and HfSiON, are promising materials for the gate electrode and gate dielectrics, respectively. This paper reports on the thermal stability of gate stack systems comprised of Ru/Hf-based dielectrics. Layers of both types of material were prepared on Si substrate by metal-organic chemical vapour deposition (MOCVD). The stacks underwent exposure by rapid thermal annealing (RTA) in pure nitrogen ambience at temperatures 800, 900, and 1000 °C for 10 s. The samples were analysed using Rutherford backscattering spectrometry (RBS). Small changes were found in the stacks treated at 800 and 900 °C. The most stable stack was found to be one with a HfSiON dielectric layer, which was resistant also at temperature 900 °C. However, the annealing at 1000 °C induced massive diffusion at both interfaces for all types of stack. The results imply a limited thermal stability of the Ru/Hf-based dielectric gate stacks during the source/drain activation step. |
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