Method for making metal plug contacts and metal lines in an insulating layer by chemical/mechanical polishing that reduces polishing- induced damage

摘要

A method for making metal plugs in via holes and interconnections by an improved chem/mech polishing process using an organic protective layer is achieved. After devices are formed on a substrate which includes a patterned conducting layer, a low-k insulating layer is deposited and planarized. An organic protective layer, such as a polymer, is deposited, and contact holes are etched in the polymer and insulating layers. A thin Ti/TiN barrier layer is deposited and a tungsten metal is deposited sufficiently thick to fill the contact holes. The tungsten metal and barrier layers are chem/mech polished back to form metal plugs, while the protective layer protects the insulating layer from CMP scratching and other CMP defects. The organic protective layer is easily removed using plasma ashing and other cleaning steps. The method is also applicable to forming metal interconnections. Trenches are etched, over and to the metal plugs, in an insulating layer having an organic protective layer. A barrier layer is deposited and a highly conductive metal, such as AlCu alloy or Cu, is deposited and are chem/mech polished back to the protective layer. The protective layer is then removed to form the metal interconnections in the insulator.