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Single Crystal Tungsten Alloy Process

IP.com Disclosure Number: IPCOM000078894D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Shang, DT: AUTHOR

Abstract

An incandescent display using a single-crystal tungsten alloy film structure provides a rugged system with reduced power consumption, improved reliability and long-life characteristics.

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Single Crystal Tungsten Alloy Process

An incandescent display using a single-crystal tungsten alloy film structure provides a rugged system with reduced power consumption, improved reliability and long-life characteristics.

At temperatures above 1500 degrees C, the polycrystal structure of tungsten is degraded. In order to overcome the problem, a single-crystal tungsten alloy structure is formed by introducing a thorium metal or its oxide into tie system. The incandescent tungsten film can be so fabricated by sputtering or by chemical vapor-deposition techniques.

If thorium oxide (ThO(2)) is utilized, a sputtering technique is employed for forming a layer of ThO(2) on the exposed surface of a tungsten (W) film which is supported by a ceramic substrate. A subsequent annealing process affixes the ThO(2) layer to the exposed W surface and changes the resultant W-Th alloyed film to a single-crystal state.

If a thorium metal is used, it is alloyed with tungsten. The alloy is formed as a film on a ceramic substrate by sputtering or by evaporation, i.e., thin film, technique. A subsequent annealing changes the W-Th to a single-crystal state.

Alternatively, a W-Th alloy film can be deposited on a ceramic substrate by a chemical vapor-deposition technique. One example of such a technique and system is shown in the figure. Hydrogen (H(2)) is provided as a carrier gas for the tungsten hexafluoride (WF(6)) and thorium fluoride (ThF(4)), which are mixed in chamber 1. The mixt...