Microstructure of 100 nm damascene copper overburden and lines studied by electron backscatter diffraction

Published

August 6, 2007

Author(s)

Roy H. Geiss, David T. Read

Abstract

A detailed understanding of the crystallography of metallic conductors in modern interconnect systems is essential if we are to understand the influence of processing parameters on performance and reliability. In particular we must be able to evaluate the grain size, crystallographic orientation and residual elastic stress for interconnect lines having widths of tens of nm. Transmission electron microscopy might be the obvious choice, but sample preparation and small sample size make this technique unattractive. On the other hand, electron backscatter diffraction, EBSD, in a scanning electron microscope provides a very attractive tool. Sample preparation can be relatively simple, especially if one investigates the structures immediately after CMP; whole wafers may be measured if desired. One limitation to EBSD is that good diffraction patterns are obtained only from free surfaces and from a limited depth, say a few hundred nm in copper. Here EBSD will be used to compare structures for the contact pads and 100-nm lines in a commercial copper damascene interconnect structure. EBSD data collection parameters will be discussed as optimized for characterizing both the texture and grain size. By a unique approach to EBSD mapping we found that neither the texture nor the grain size of the overburden, as represented by the contact pads, propagated into the 100 nm lines, though they did propagate into some wider lines.

Proceedings Title

SPIE Proceedings, Nano Science and Engineering 2007

Conference Dates

August 26-30, 2007

Conference Location

San Diego, CA, USA

Conference Title

SPIE Optics and Photonics, Nano Science and Engineering

Pub Type

Conferences

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Keywords

copper, damascene, grain size, preferred orientation, texture, twinning

Citation

Geiss, R. and Read, D. (2007), Microstructure of 100 nm damascene copper overburden and lines studied by electron backscatter diffraction, SPIE Proceedings, Nano Science and Engineering 2007, San Diego, CA, USA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50619 (Accessed December 15, 2024)