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Multilayer Ground Plane Fabrication

IP.com Disclosure Number: IPCOM000090474D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Ahn, KY: AUTHOR

Abstract

A high-conductivity metal ground plane for a magnetic film miniarray is fabricated upon a silicon wafer or other semiconductor substrate. This is effected by a method which prevents undesirable grain growth in the high-conductivity metal and also inhibits diffusion of the semiconductor material into the ground plane.

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Multilayer Ground Plane Fabrication

A high-conductivity metal ground plane for a magnetic film miniarray is fabricated upon a silicon wafer or other semiconductor substrate. This is effected by a method which prevents undesirable grain growth in the high-conductivity metal and also inhibits diffusion of the semiconductor material into the ground plane.

For best operation, a miniarray supported by a semiconductor substrate requires a ground plane of much higher conductivity than the substrate. A ground plane of the desired conductivity is formed by depositing alternate layers of refractory metal and high-conductivity metal upon the silicon wafer or other substrate. The ground plane is built up to a depth of 5 to 6 microns. Preferably the thickness of each refractory layer is around 500 Angstroms. Each high- conductivity layer is about 5,000 Angstroms thick. The refractory layers serve as diffusion barriers between the high-conductivity metal and the semiconductor and also improve the adhesion of the ground plane layers to the substrate. Undesired grain growth of the high-conductivity metal in the ground plane is inhibited by the fact that none of these layers is more than 5,000 Angstroms thick.

Where vacuum deposition is employed to form the ground plane, the refractory metal employed is molybdenum, titanium, niobium or chromium. A highly conductive noble metal such as gold or silver is employed to form the other layers. The silicon wafer is outgassed and heated t...