Abstract: Disclosed is a method, system and apparatus for filling a gap feature on a substrate surface, comprising providing a substrate with a surface comprising a gap feature in a reaction chamber, depositing a first material layer into the gap feature with a first cyclic deposition process, etching the first material layer to form a base in a bottom portion of the gap feature with a cyclic etching process and partially filling the gap feature with a second material layer with a second cyclic deposition process.