Method of topology-selective film formation of silicon oxide

A method for forming a silicon oxide film on a step having a top surface, a sidewall, and a bottom surface formed on a substrate, comprising processes of:

• (a) designing a topology of a final silicon oxide film, which is a conformal film or a film having low conformality, formed on the step by preselecting a target portion of an initial silicon nitride film to be selectively deposited or removed or reformed with reference to a non-target portion of the initial silicon nitride film resulting in the final silicon oxide film, said selectively deposited target portion being a top/bottom portion of the initial silicon nitride film formed on the top and bottom surfaces of the step, said selectively removed or reformed target portion being a sidewall portion of the initial silicon nitride film formed on the sidewall of the step;
• and
• (b) forming the initial silicon nitride film and the final silicon oxide film on the surfaces of the step according to the topology designed in process (a), wherein the initial silicon nitride film is deposited by atomic layer deposition (ALD) using a silicon-containing precursor containing halogen, and the initial silicon nitride film is converted to the final silicon oxide film by oxidizing the initial silicon nitride film without further depositing a film wherein a Si—N bond in the initial silicon nitride film is converted to a Si—O bond,
• wherein the target portion preselected in process (a) is the selectively deposited target portion, and wherein process (b) comprises:
• (ci) depositing a silicon oxide film on the surfaces of the step on the substrate;
• and
• (cii) anisotropically nitriding a surface of the silicon oxide film using a nitrogen-hydrogen-containing plasma generated by applying RF power between two electrodes between which the substrate is placed in parallel to the two electrodes, in a manner nitriding the surface of the silicon oxide film predominantly on the top and bottom surfaces of the step, rather than on the sidewall of the step, thereby introducing —NH terminals on the surface of the silicon oxide film.