Method for encapsulating a metal via in damascene

摘要

Disclosed is a method for encapsulating a via over a first metal layer of a semiconductor substrate in a damascene processing to prevent voiding. The method includes forming an intermetal oxide (IMO) layer over the first metal layer and forming a via in the IMO layer such that the via exposes a portion of the first metal layer and a side wall of the via in the IMO layer. The method also includes conformally forming a first barrier layer over the IMO layer and the via such that a portion of the first barrier layer is deposited over the side wall of the IMO layer and the exposed portion of the first metal layer. The method further includes depositing a second metal layer over the first barrier layer such that the second metal layer fills the via within the first barrier layer portion deposited in the via to form a metal via. Additionally, the method includes removing the second metal layer and the first barrier layer above a top portion of the IMO layer and forming a trench in a portion of the IMO layer in contact with the first barrier layer to a specified depth. The method further includes forming a second barrier layer in the trench. The method also forming a third metal layer over the second barrier layer in the trench to form a metal trench such that the metal via is encapsulated by the first barrier layer so as to reduce electromigration effect in the metal via.