The process of the present invention forms copper interconnects in a semiconductor
wafer surface. During the process, initially, narrow and large features are provided
in the top surface of the wafer, and then a primary copper layer is deposited by
employing an electrochemical deposition process. The primary copper layer completely
fills the features and forms a planar surface over the narrow feature and a non-planar
surface over the large feature. By employing an electrochemical mechanical deposition
process, a secondary copper layer is deposited onto the primary copper layer to
form a planar copper layer over the narrow and large features. After this process
step, the thickness of the planar copper layer is reduced using an electropolishing process.