Accession Number : ADD009178

Title :   Method Producing Smooth Metallic Layers on a Substrate.

Descriptive Note : Patent Application,

Corporate Author : DEPARTMENT OF THE ARMY WASHINGTON DC

Personal Author(s) : Murphy,Joseph

Report Date : 11 Jan 1982

Pagination or Media Count : 5

Abstract : This invention relates in general to a method of producing a smooth layer of a metal on a substrate and in particular, to a method of producing a smooth layer of a metal on a glass substrate wherein a large differential expansion coefficient of the metal relative to the glass substrate produces very large stresses in the metal when the metallized substrate is subjected to a post deposition anneal. Thin film conductors separated by thin film insulators are the dominant components of thin film circuitry. Electrical shorts in these components may result from roughness in the bottom conductor. The roughness can develop during the depositions of the metal but it increases when the substrate is annealed. Aluminum is a commonly used conductor material for thin film circuits. Pure aluminum films on glass become badly pock marked with spikes after an eight to ten hour anneal at 400 C. The spikes are believed to develop because the large differential expansion coefficient of the aluminum relative to the glass produces very large stresses in the aluminum. The stress is relieved and the energy thereby reduced when the aluminum atoms migrate in the plane of the film to nucleation centers where crystallites grow in the third dimension, out of the plane, viz, spikes.

Descriptors :   *Patent applications, *Metals, *Layers, *Thin films, *Substrates, Production, Methodology, Stresses, Annealing, Deposition, Expansion, Diffusion coefficient, Electric conductors, Electrodes, Transistors, Aluminum, Copper, Glass

Subject Categories : Electrical and Electronic Equipment
      Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE