Dual damascene process which prevents diffusion of metals and improves trench-to-via alignment

Abstract

Disclosed is a dual damascene process for a semiconductor device with two low dielectric constant layers in a stack thereof, in which a via hole and a trench connecting with the via hole are formed respectively in the dielectric layers and a conductor is filled in the via hole and the trench to connect with a conductive region below the via hole after a barrier layer between the via hole and the conductive region is removed. A liner is deposited on the sidewalls of the dielectric layers in the via hole and the trench before the removal of the barrier layer to prevent particles of the conductive region such as copper from sputtering up to the dielectric layers when removing the barrier layer. An etch-stop layer inserted between the dielectric layers is pulled back to be spaced from the via hole with a distance to improve the trench-to-via alignment.