Abstract: Embodiments are disclosed for a method to process microelectronic workpieces including forming a metal hard mask layer including ruthenium (Ru MHM layer) over one or more underlying layers on a substrate for a microelectronic workpiece, etching the Ru MHM layer to provide a patterned Ru MHM layer, and etching the one or more underlying layers using the patterned Ru MHM layer as a mask to protect portion of the one or more underlying layers. For one embodiment, the Ru MHM layer is a material including 95 percent or more of ruthenium (Ru). For another embodiment, the Ru MHM layer is a material including 70 percent or more of ruthenium (Ru). Further, the Ru MHM layer preferably has a selectivity of 10 or greater with respect to a next underlying layer adjacent to the Ru MHM layer, such as a SiN hard mask layer.

Abstract: A method for the via etching steps of a substrate manufacturing process flow is provided. The substrate processing techniques described provide for etching vias by providing a protection layer on the via sidewall during at least portions of the via etching process. In one embodiment, an atomic layer deposition (ALD) layer is formed on the via sidewalls to protect the dielectric layers through which the via is formed. The ALD layer may lessen bowing effects in low k dielectric layers which may result from etching barrier low k (blok) layers or from other process steps. After via formation, the ALD layer may be removed. The techniques are particularly suited for forming skip vias and other high aspect ratio vias formed in low k and ultra-low k dielectric layers.