Sealing porous structures

Abstract

Method and structures are provided for conformal lining of dual damascene structures in integrated circuits, and particularly of openings formed in porous materials. Trenches and contact vias are formed in insulating layers. The pores on the sidewalls of the trenches and vias are blocked, and then the structure is exposed to alternating chemistries to form monolayers of a desired lining material. In exemplary process flows chemical or physical vapor deposition (CVD or PVD) of a sealing layer blocks the pores due to imperfect conformality. An alternating process can also be arranged by selection of pulse separation and/or pulse duration to achieve reduced conformality relative to a self-saturating, self-limiting atomic layer deposition (ALD) process. In still another arrangement, layers with anisotropic pore structures can be sealed by selectively melting upper surfaces. Blocking is followed by a self-limiting, self-saturating atomic layer deposition (ALD) reactions without significantly filling the pores.