Partially self-aligned metal contact process

Abstract

In a semiconductor device fabrication process, the SILO (Sealed Interface Local Oxidation) field oxide formation process is used to provide essentially vertical sidewalls between the field oxide surface and active regions. After field oxide formation and doping of active regions, the device is conformally coated with an oxide layer, which is patterned by a conventional photomasking process to define contact holes. Contact holes are then anisotropically etched through the oxide layer to the active regions. Conformal coating of the vertical sidewalls insures that an oxide sidewall spacer remains where the contact holes intersect the field oxide. Finally, a metal contact layer is deposited in the contact holes. The sidewall spacer automatically spaces the metal contact from the edges of the active region, thereby preventing leakage to the substrate.