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Double Layer Insulation at Conductor Crossovers in Integrated Circuits

IP.com Disclosure Number: IPCOM000093147D
Original Publication Date: 1967-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Maddocks, FS: AUTHOR [+2]

Abstract

Improved insulation is achieved at conductor crossover layer areas in multilayer integrated circuits using double-layer insulation. Lower conductor 10 on substrate 1 1 has its upper surface anodized in the region of the crossover to form thin insulating barrier 12. Superimposed by vapor deposition or like technique on conductor 10 in the crossover region is layer 13 of dielectric such as SiO. Upper conductor 14, the crossover conductor, is vacuum deposited on layer 13 and is subsequently coated with a further protective dielectric layer not shown. Conductor metals such as aluminum are useful for this construction.

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Double Layer Insulation at Conductor Crossovers in Integrated Circuits

Improved insulation is achieved at conductor crossover layer areas in multilayer integrated circuits using double-layer insulation. Lower conductor 10 on substrate 1 1 has its upper surface anodized in the region of the crossover to form thin insulating barrier 12. Superimposed by vapor deposition or like technique on conductor 10 in the crossover region is layer 13 of dielectric such as SiO. Upper conductor 14, the crossover conductor, is vacuum deposited on layer 13 and is subsequently coated with a further protective dielectric layer not shown. Conductor metals such as aluminum are useful for this construction.

Without anodizing, dendrites form on the aluminum conductor, e.g., during subsequent thermal treatment, causing weak points to develop in layer 13 from which breakdown occurs when subject to electrical stress. Layer 13 minimizes breakdown due to any weak spots in anodized layer 12 which is relatively thin. The insulating effect of combined layers 12 and 13 permits layer 13 to be much thinner, thus realizing better control over capacitance in the crossover region.

The anodization is preferably performedinthe thin-film fabrication process between the steps of forming conductor patterns with resistor and capacitor plates, if any, and the heat-treating of the resistors. A screening technique which exposes only the crossover areas is used in preparation for anodizing.

The connection of th...