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Self-formation of Ti-rich Layers at Cu(Ti)/low-k Interfaces

Published online by Cambridge University Press:  01 February 2011

Kazuyuki Kohama ,
Kazuhiro Ito ,
Susumu Tsukimoto ,
Kenichi Mori ,
Kazuyoshi Maekawa  and
Masanori Murakami
Kazuyuki Kohama
Affiliation:
k.kohama@eng.mbox.media.kyoto-u.ac.jp, Kyoto University, Materials Science and Engineering, Yoshida-Honmachi, Sakyo-ku, Kyoto, 606-8501, Japan
Kazuhiro Ito
Affiliation:
kazuhiro.ito@materials.mbox.media.kyoto-u.ac.jp, Kyoto University, Department of Materials Science and Engineering, Kyoto, 606-8501, Japan
Susumu Tsukimoto
Affiliation:
susumu.tsukimoto@materials.mbox.media.kyoto-u.ac.jp, Kyoto University, Department of Materials Science and Engineering, Kyoto, 606-8501, Japan
Kenichi Mori
Affiliation:
mori.kenichi@renesas.com, Renesas Technology Corp., Process Technology Development Division, Itami, 664-0005, Japan
Kazuyoshi Maekawa
Affiliation:
maekawa.kazuyoshi@renesas.com, Renesas Technology Corp., Process Technology Development Division, Itami, 664-0005, Japan
Masanori Murakami
Affiliation:
murakam@fc.ritsumei.ac.jp, Kyoto University, Department of Materials Science and Engineering, Kyoto, 606-8501, Japan
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Abstract

In our previous studies, thin Ti-rich diffusion barrier layers were found to be formed at the interface between Cu(Ti) films and SiO2/Si substrates after annealing at elevated temperatures. This technique was called “self-formation of the diffusion barrier,” which is attractive for fabrication of ultra-large scale integrated (ULSI) interconnects. In the present study, we investigated the applicability of this technique to Cu(Ti) alloy films which were deposited on the four low dielectric constant (low-k) dielectric layers which are potential dielectric layers of future ULSI-Si devices. The microstructures were analyzed by transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS), and correlated with the electrical properties of the Cu(Ti) films. It was concluded that the Ti-rich interface layers were formed in all the Cu(Ti)/dielectric-layer samples. The primary factor to control composition of the self-formed Ti-rich interface layers was the C concentration in the dielectric layers rather than the formation enthalpy of the Ti compounds (TiC and TiSi). Crystalline TiC was formed on the dielectric layers with a C concentration higher than 17 at.%.

Keywords

barrier layerannealingdiffusion
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1079: Symposium N – Materials and Processes for Advanced Interconnects for Microelectronics , 2008 , 1079-N03-08
Copyright
Copyright © Materials Research Society 2008

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References

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