Contact plug forming method

摘要

An inter-level insulation film is formed on a first-level interconnection layer and part of the inter-level insulation film which lies on the first-level interconnection layer is etched to form a contact hole. After a natural oxidation film formed on the surface of part of the first-level interconnection layer which is exposed in the contact hole is removed, the resultant structure is exposed to a gas atmosphere containing halogen to purify the surface of the inter-level insulation film. After this, a contact plug is deposited and formed on the first-level interconnection layer which is exposed in the contact hole by the selective CVD method to fill in the contact hole. A second-level interconnection layer is formed on the inter-level insulation film and the first-level and second-level interconnection layers are electrically connected to each other via the contact plug.