Method for fabricating electrode structure for a semiconductor device having a shallow junction
AssigneeNippon Electric Co., Ltd.
InventorsHideo Tsunemitsu, Hiroshi Shiba
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Abstract
A thermally stable semiconductor device is disclosed in which a thin aluminum film is formed over a silicon oxide film selectively formed on the silicon substrate. A layer of a metal such as tantalum, tungsten, or molybdenum that does not enter into an alloy reaction with silicon at heat treatment temperatures is formed over the thin aluminum film and is covered with a thick aluminum film. Oxides of the upper thick aluminum layer as well as oxides of the non-alloying metal and the lower aluminum layer are selectively formed in alignment with one another at locations where the electrodes are not formed.
Claims13
A method of fabricating a semiconductor device comprising the steps of providing a semiconductor substrate, forming an insulating film over the upper surface of said substrate except for predetermined portions thereof, successively forming first, second, and third metal layers on said substrate and said insulating film, said first metal layer being capable of being alloyed with said semiconductor substrate at a first temperature, said first metal layer having a thickness less than the depth of the shallowest junction in the substrate, said second metal layer being capable of being alloyed with said substrate at a second temperature higher than said first temperature, said third metal layer having a good electric conductivity and being thicker than any of said first and second metal layers, anodically oxidizing said third metal layer to convert the selected portion thereof into an insulator to the surface of said second metal layer, anodically oxidizing those portions of said second and first metal layers which are aligned with said selected portion of said third metal layer, and thereafter performing heat treatment for alloying a portion of said first metal layer with said substrate at a temperature below said second temperature.
A method of fabricating a semiconductor device comprising the steps of providing a semiconductor substrate, forming an insulating film over the upper surface of said substrate except for predetermined portions thereof, forming a first aluminum layer on said substrate and said insulating film, forming a tantalum layer of a substantially uniform thickness on said first aluminum layer, forming a second aluminum layer of a thickness greater than that of either of said first aluminum layer and said tantalum layer on said tantalum layer, carrying out an anodic oxidation treatment to convert selectively aligned portions of said first aluminum layer, said tantalum layer and said aluminum layer into an insulator region, and performing heat treatment for alloying a portion of said first aluminum layer with said semiconductor substrate.
Dependencies are inferred from the claim text.