METHOD FOR FORMING COPPER PLUG BY USING DUAL DAMASCENE TECHNIQUE

摘要

PURPOSE: A method for forming a copper plug by using a dual damascene technique is provided to prevent the creation of dishing on the copper plug. CONSTITUTION: The first and second interlayer dielectrics(20,30) are formed on a semiconductor substrate(10) and then etched to form a dual contact hole therein. Next, a barrier layer(50) is deposited on the resultant structure including the contact hole. The contact hole is then filled with a copper layer forming a hollow portion in the contact hole. Thereafter, a tantalum nitride layer(80) is deposited to fill the hollow portion of the copper layer, and an insulating layer(70) is formed thereon. The resultant structure is then planarized by a chemical mechanical polishing, so that a copper plug(90) is formed by the planarized copper layer. The polishing continues until the barrier layer(50) is exposed, so that the insulating layer(70) in the hollow portion is removed and further the copper plug(90) remains only in the contact hole. After that, the exposed barrier layer(50) is wholly removed. The conventional dishing phenomenon on the copper plug(90) is prevented by the tantalum nitride layer(80) in the hollow portion.