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Microstructural Evolution in Copper Films Undergoing Laser Pulsing at High Pressures

Published online by Cambridge University Press:  10 February 2011

R. Jakkaraju ,
C. D. Dobson  and
A. L. Greer
R. Jakkaraju
Affiliation:
University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ, UK
C. D. Dobson
Affiliation:
University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ, UK
A. L. Greer
Affiliation:
University of Cambridge, Department of Materials Science and Metallurgy, Pembroke Street, Cambridge CB2 3QZ, UK
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Abstract

A novel process of pulse-heating copper films under high pressure has been developed for filling high-aspect-ratio vias and contact holes with copper. A copper film is sputter-deposited on to an oxidised silicon substrate containing an array of via holes with varied aspect ratios. The film, which is thick enough to bridge over the via holes, is then subjected to laser pulse heating under selected pressures of inert gas. Via filling has been achieved, up to an aspect ratio of 6 for 0.35 μm diameter holes. The microstructure of the pulse-heated copper films has been investigated by X-ray diffraction, and by focused ion beam microscopy (FIB) including sectioning. The FIB images of the film over a via pattern show a ‘chequer-board’ pattern of grains corresponding to the square pattern of via holes underneath. This pattern can be explained by transient melting of the film under pulse-heating and subsequent solidification in which each via hole acts as a nucleation site and has a crystal associated with it. Even though the as-deposited films are fine-grained and have (111) texture, the treated films can show (111) or (100) texture, depending on processing conditions. The origins of the final film texture and the possibilities for microstructural control are discussed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 594: Symposium V – Thin Films - Stresses & Mechanical Properties VIII , 1999 , 111
Copyright
Copyright © Materials Research Society 2000

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References

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