CVD Synthesis of Tungsten Nitride and lts Deposition Behavior

The synthesis and deposition behavior of tungsten nitrides on a Si(400) or quartz plate were studied using a vertical hot-wall tube reactor. The preparation of the tungsten nitride by chemical vapor deposition (CVD) is predicted by the sticking probability of tungsten nitride by calculating the step coverage on the Si(400) engraved with a microtrench of different aspect ratios. The CVD deposition was performed at temperatures of 556–1063 K for deposition times up to 45 min in a gas mixture of WF6–NH3–H2 in Ar and at a total pressures of 5 and 13 Pa. From the XRD analysis, amorphous crystallites were observed at 556 and 673 K but β–W2N (111) was obtained at 790 K. The film thickness of the tungsten nitride linearly increased with the increasing deposition time at 673 and 790 K without any orientation despite the film thickness. The sticking probabilities, η, are 0.00044–0.00123 for Si(400) with different aspect ratios under the conditions of 5–13 Pa and 10–20 min.