Process for improving copper fill integrity

摘要

A method for eliminating the problems associated with the discontinuous deposition of the glue layer at the bottom of the via resulting from the notch in the silicon nitride etch stop layer. First conductive layer traces are patterned and a silicon nitride (SiN) etch stop layer is provided overlying the first conductive layer. An inter-metal dielectric (IMD) layer then overlies the entire surface. An anisotropic etch is performed leaving via holes in the IMD layer. This is followed by a second anisotropic etch step to remove the etch stop layer not protected by the IMD layer resulting in the formation a notch at the bottom of the via hole. An important step of the present invention is the elimination of this notch accomplished by nitridizing the surface of the IMD layer. A wet polymer cleaning is performed to remove the nitridized IMD surface and eliminating the notch. A glue layer is conformally applied lining the via hole. A second conductive layer is then deposited and the surface is planarized.