Method for making a fillet for integrated circuit metal plug

摘要

A well in a semiconductor wafer is partially filled by a tungsten plug having an irregular surface. There is an aluminum line exterior of the well for electrically connecting the tungsten plug into an electrical circuit. A doped polysilicon fillet having an irregular surface meshing with the irregular surface of the tungsten plug fills the portion of the well between the plug and line, making a reproducible good electrical connection between the tungsten plug and the aluminum line. The poly fillet is formed by a poly deposit and planarization performed between a tungsten plug overetch and aluminum line deposition.