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Epitaxial Copper Films on Sapphire

IP.com Disclosure Number: IPCOM000092112D
Original Publication Date: 1968-Sep-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Katz, G: AUTHOR

Abstract

This method of growth of face-centered cubic single-crystal copper films on a sapphire alpha- Al(2)O(3) substrate occurs at temperatures far below those used in previous processes. The copper films are vacuum-evaporated using conventional RF induction-heated tantalum crucibles. The films are prepared from 99.999+% pure copper pellets in a stainless steel, silicone oil diffusion vacuum pump employing a liquid nitrogen trap capable of providing a vacuum of 1-5 x 10/-6/ Torr. The source to substrate distance is 10'' and the deposition rate is of the order of 100 angstroms sec. Single-crystal films, 5-7 mu thick with 1.69 x 10/-6/ ohm-cm resistivity, are obtained with the substrate temperature in the range of 240-375 degrees C.

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Epitaxial Copper Films on Sapphire

This method of growth of face-centered cubic single-crystal copper films on a sapphire alpha- Al(2)O(3) substrate occurs at temperatures far below those used in previous processes. The copper films are vacuum-evaporated using conventional RF induction-heated tantalum crucibles. The films are prepared from
99.999+% pure copper pellets in a stainless steel, silicone oil diffusion vacuum pump employing a liquid nitrogen trap capable of providing a vacuum of 1-5 x 10/-6/ Torr. The source to substrate distance is 10'' and the deposition rate is of the order of 100 angstroms sec. Single-crystal films, 5-7 mu thick with 1.69 x 10/-6/ ohm-cm resistivity, are obtained with the substrate temperature in the range of 240-375 degrees C. Epitaxial copper films are only obtained when the substrate surface is within 4 degrees of the (0001) plane of sapphire. When the sapphire substrates are oriented normal to the boule axis direction approximately 60 degrees from the >0001|, the copper films are polycrystalline. The epitaxial relationship is: (111)(Cu) (0001)(alpha-Al(2)O(3)

>211| >2110|(alpha-Al(2)O(3). The resulting films are twinned with the twin crystal exhibiting a 60 degree rotation about the >111| direction of copper.

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