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An atomic layer deposition process to grow tungsten nitride films was established at 350°C with a pulse sequence of WF 6 /NH 3 /C 2 H 4 /SiH 4 /NH 3 . The film composition was determined with Rutherford backscattering as W 1.5 N, being a mixture of WN and W 2 N phases. The growth rate was ϳ1 ϫ 10 15 W atom/cm 2 per cycle ͑monolayer of W 2 N or WN͒. The films with a thickness of 16 nm showed root-mean-square roughness as low as 0.43-0.76 nm. The resistivity of the films was stable after 50 cycles at a value of 480 ⍀ cm. Results of four-point probe sheet resistance measurements at elevated temperature demonstrated that our films are nonreactive with Cu at least up to 500°C. Results of I-V measurements of p + /n diodes before and after heat-treatment in ͑N 2 + 5% H 2 ͒ ambient at 400°C for 30 min confirmed excellent diffusion barrier properties of the films.

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