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Post Titanium Silicide Processing

Published online by Cambridge University Press:  15 February 2011

G. Grynkewich
Affiliation:
Motorola Advanced Custom Technologies, Mesa, AZ 85202
V. Ilderem
Affiliation:
Motorola Advanced Custom Technologies, Mesa, AZ 85202
M. Miller
Affiliation:
Motorola Materials Technology Center, Mesa. AZ 85202
S. Ramaswami
Affiliation:
Motorola MOS 6 Manufacturing, Mesa, AZ 85202
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Abstract

Decreasing contact dimensions coupled with the need for planarization to accommodate multiple layers of metal have created many challenges for the contact etch module. For example, contact etch processes are often required to stop on thin titanium silicide while at the same time forming high aspect ratio, straightwalled contacts. In this paper, the impact of various dielectric compositions and contact etch process parameters on etch profile, selectivity, and contact resistance is presented for the formation of high aspect ratio, submicron contacts to thin TiSi2 layers. The etch profile is formed by RIE using a mixture of CHF3 and various amounts of CF4. Surprisingly, the sidewall angle and selectivity to silicide showed little dependence on the percent CF4. Contact resistance measurements, however, varied greatly with percent CF4 and contact aspect ratio. The variation of contact resistance with etch chemistry was attributed to a variation in the extent of fluorocarbon polymer film formation, which in turn depends on the ratio of carbon to fluorine in the plasma. Finally, post contact etch treatments were examined for efficiency in removing the polymer films from the high aspect ratio contacts.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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