Method of forming conformal film having si-N bonds on high-aspect ratio pattern

A method of forming a conformal dielectric film having Si—N bonds on a substrate having a patterned surface, comprising:

• introducing a reactant gas into a reaction space inside which the substrate is placed;
• introducing a silicon precursor in pulses of less than 5-second duration into the reaction space, wherein one pulse of the silicon precursor and one immediately following interval devoid of the silicon precursor, which interval is between the one pulse and one next pulse of the silicon precursor, constitute one cycle of reaction;
• applying a first RF power to the reaction space during the pulse of the silicon precursor in each cycle;
• applying a second RF power to the reaction space during the interval of the silicon precursor pulse in each cycle, wherein an average intensity of the second RF power during the interval of the silicon precursor pulse is greater than that of the first RF power during the pulse of the silicon precursor in each cycle;
• and
• repeating the cycle to form a conformal dielectric film having Si—N bonds with a desired thickness on the patterned surface of the substrate.