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Mechanical Integrity Study of Air Gap Structures Assisted by FE Simulations

Published online by Cambridge University Press:  01 February 2011

Stephane Moreau ,
Fré;déric Gaillard ,
Jean-Charles Barbé ,
Raphaël Gras ,
Gérard Passemard  and
Joaquin Torres
Stephane Moreau
Affiliation:
[email protected], CEA, DRT/LETI/LBE, 17 rue des Martyrs, Grenoble, 38054, France
Fré;déric Gaillard
Affiliation:
[email protected], CEA-LETI MINATEC, DRT/LETI/LBE, 17 rue des Martyrs, Grenoble, 38054, France
Jean-Charles Barbé
Affiliation:
[email protected], CEA-LETI MINATEC, DRT/LETI/LSCDP, 17 rue des Martyrs, Grenoble, 38054, France
Raphaël Gras
Affiliation:
[email protected], STMicroelectronics, 850 rue Jean Monnet, Crolles, 38926, France
Gérard Passemard
Affiliation:
[email protected], STMicroelectronics, 850 rue Jean Monnet, Crolles, 38926, France
Joaquin Torres
Affiliation:
[email protected], STMicroelectronics, 850 rue Jean Monnet, Crolles, 38926, France
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Abstract

In this paper, mechanical reliability of “air gap” structures has been evaluated when a copper line is completely surrounded with air. Different Finite Element (FE) simulation models have been used on a 2-metal level structure to study the M2 copper line bow evolution as a function of its dimensions if complete air cavities are generated underneath (i.e. at via level). Design rules information may therefore be obtained to optimize “air gap” integration considering the 65 nm and 22 nm technology nodes. Thus, we not only highlight that M2 copper line can not collapse considering our failure criterion but that M2 bow variation may also be improved when a tensile SiCN capping layer is deposited on top of the structure. The influence of the interline spacing vs. M2 bow has also been studied and we show that its increase is a beneficial parameter for the air gap structure. In opposite, we demonstrate that buckling can occur when a compressive SiCN layer is used. Finally, we accurately predict the M2 bow variation for air gap structures of the 65 nm and 22 nm technology nodes, but stress and strain distribution can complementary be provided. Those results highlight interesting criteria for designers to build reliable air gap structures.

Keywords

Cusimulationmicroelectronics
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1079: Symposium N – Materials and Processes for Advanced Interconnects for Microelectronics , 2008 , 1079-N02-02
Copyright
Copyright © Materials Research Society 2008

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References

REFERENCES

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