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A Study on the Properties of Different IMP Ta, Ta(N) and Multi-Layer Ta/Ta(N) as Diffusion Barriers for Cu Metallization

Published online by Cambridge University Press:  17 March 2011

L. He ,
C.Y. Li ,
Z.Q. Zeng ,
J.J. Wu ,
Y. Qian ,
Y. Zhang ,
H.D. Liu  and
Joseph Xie
L. He
Affiliation:
Advanced Materials Program, Singapore-MIT Alliance, Singapore Dept of Deep Submicron Integrated Circuit, Institute of Microelectronics, Singapore
C.Y. Li
Affiliation:
Dept of Deep Submicron Integrated Circuit, Institute of Microelectronics, Singapore
Z.Q. Zeng
Affiliation:
School of Materials Engineering, Nanyang Technological University, Singapore
J.J. Wu
Affiliation:
Dept of Deep Submicron Integrated Circuit, Institute of Microelectronics, Singapore
Y. Qian
Affiliation:
Dept of Deep Submicron Integrated Circuit, Institute of Microelectronics, Singapore
Y. Zhang
Affiliation:
Advanced Materials Program, Singapore-MIT Alliance, Singapore Dept of Deep Submicron Integrated Circuit, Institute of Microelectronics, Singapore
H.D. Liu
Affiliation:
Rudolph Technologies, Inc., Flanders, NJ
Joseph Xie
Affiliation:
Advanced Materials Program, Singapore-MIT Alliance, Singapore Dept of Deep Submicron Integrated Circuit, Institute of Microelectronics, Singapore
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Abstract

We report a study on the properties of Ionized Metal Plasma (IMP) Ta, Ta(N) and multi-layer Ta/Ta(N) based on a comparative evaluation of their performance as diffusion barriers in Cu based metallization schemes. The film structures used in this study are: IMP Cu(2000Å)/IMP Ta(250Å)/Si; IMP Cu(2000Å)/IMP Ta(N)(250Å)/Si; and IMP Cu(2000Å)/IMP multi-layer Ta/Ta(N)(250Å)/Si. The samples were annealed in N2 ambient at 500 °C, 550°C, 600°C and 650°C, respectively, for 30 minutes. The failure behavior and film properties of different barriers were investigated using MetaPULSE, Film stress measurement (FSM), Four-point probe (FPP), X-ray diffractometry (XRD), Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM). It has been observed clearly from the sheet resistance measurements that failures of Ta(N) and Ta barriers occurred at 550°C and 600°C respectively, whereas the multi-layer Ta/Ta(N) could still survive from the annealing up to 650°C. Evidence showing the formation of Cu3Si in the failed film stacks was found from XRD spectra. Based on our studies, it can be concluded that microstructures of the barriers has the major effects on preventing Cu from diffusing through them to react with Si and this makes the multi-layer Ta/Ta(N), in overall, superior to the other two Ta and Ta(N) barriers.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 714: Symposium – Materials, Technology and Reliability for Advanced Interconnects and Low-k Dielectrics II , 2001 , L5.6.1
Copyright
Copyright © Materials Research Society 2001

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References

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