Smooth titanium nitride layers and methods of forming the same

A method of forming a thin film comprising titanium nitride (TiN), the method comprising:

• providing a semiconductor substrate comprising a non-metallic surface;
• forming on the non-metallic surface a seed layer comprising a TiSiN layer by thermal atomic layer deposition (ALD) without aid of a plasma;
• and
• forming on the seed layer and in situ in a same chamber a TiN layer by thermal ALD without aid of a plasma,
• wherein forming the seed layer comprises alternatingly exposing the semiconductor substrate to one or more cycles, each of the one or more cycles comprising an exposure to a Si precursor, an exposure to a Ti precursor following the exposure to the Si precursor without an intervening exposure to a N precursor, and an exposure to a N precursor following the exposure to the Ti precursor without an intervening exposure to a Si precursor, thereby forming the TiSiN layer,
• wherein a thickness ratio of the TiN layer to the seed layer exceeds 5, and
• wherein an electrical resistivity of a stack comprising the TiN layer formed on the seed layer is less than about 200 μΩ-cm.