Barrier Effect of TaSiN Layer for Oxygen Diffusion

The barrier effect for oxygen diffusion is studied in TaSiN layers. The TaSiN is deposited by reactive sputtering employing Ta and Si targets. The composition of the layer ranges from Ta{sub 0.16}Si{sub 0.27}N{sub 0.57} to Ta{sub 0.55}Si{sub 0.07}N{sub 0.38} by varying the Ta target power from 100 to 400 watts (W). A resistivity of 210 {micro}{Omega} cm is obtained for the Ta{sub 0.55}Si{sub 0.07}N{sub 0.38} layer. The surface oxidation and in-diffusion of oxygen to a depth of 15 nm into the Ta{sub 0.30}Si{sub 0.17}N{sub 0.53} layer are observed by annealing in O{sub 2} at 650 C. However, the oxygen diffusion is suppressed in the Ta{sub 0.55}Si{sub 0.07}N{sub 0.38} layer. No out-diffusion of oxygen occurs from the Ta{sub 2}O{sub 5} dielectric layer to the amorphous barrier layer. This result shows that a low Si concentration layer for instance, Ta{sub 0.55}Si{sub 0.07}N{sub 0.38} is a promising barrier layer for oxygen diffusion and is useful for charge storage capacitors for MOS memory devices.