Abstract: Embodiments of the present invention relate to methods and apparatus for depositing a silicon nitride film. More particularly, embodiments of the present invention relate to methods and apparatus for depositing a silicon nitride film by cyclical layer deposition. One method for depositing a silicon nitride film generally comprises separately introducing one or more pulses of a nitrogen precursor and one or more pulses of a silicon precursor to a region adjacent to the substrate surface. A portion of the pulses of the nitrogen precursor and a portion of the pulses of the silicon precursor are present together at the region adjacent the substrate surface. Another embodiment for depositing a silicon nitride film comprises dosing a continuous flow of a purge gas with at least one pulse of a silicon precursor and at least one pulse of a nitrogen precursor. Each pulse of the silicon precursor and the nitrogen precursor is provided for a time period between about 0.01 seconds and about 2.0 seconds.