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A Systematic Approach of Understanding and Retaining Pmos Compatible Work Function of Metal Electrodes On HfO2 Gate Dielectrics

Published online by Cambridge University Press:  01 February 2011

Rashmi Jha
Affiliation:
rjha@ncsu.edu, North Carolina State University, Department of Electrical and Computer Engineering, 2410 Campus Shore Drive, North Carolina State University,, Raleigh, NC, 27695, United States, 919-515-5347
Jiyoung Chung
Affiliation:
jchoung@ncsu.edu, North Carolina State University, Department of Physics, Raleigh, NC, 27695, United States
Bei Chen
Affiliation:
bchen2@ncsu.edu, North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, NC, 27695, United States
Robert Nemanich
Affiliation:
robert_nemanich@ncsu.edu, North Carolina State University, Department of Physics, Raleigh, NC, 27695, United States
Veena Misra
Affiliation:
vmisra@ncsu.edu, North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, NC, 27695, United States
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Abstract

In this work we have performed Ultraviolet Photoelectron Spectroscopy (UPS) and X-Ray Photoelectron Spectroscopy (XPS) on: (i) 40Å of Ru deposited on 20Å of ALD-HfO2 (Ru-HfO2), (ii) 40Å of Re deposited on 20Å of ALD-HfO2 (Re-HfO2), and (iii) 40Å of W deposited on 20Å of ALD-HfO2 (W-HfO2) in as deposited as well as after 600˚C in-situ anneal exposure. The samples with Ru and Re indicated significant reduction in the oxygen content and shift in the Hf peaks towards higher binding energy after anneal as compared to the as deposited state. The loss of oxygen after anneal was associated with the reduction in the surface work function of Ru and Re measured by UPS. However, the sample with W showed a redistribution of oxygen after anneal leading to the formation of multiple oxides of W having a net higher surface work function. The spectroscopic measurements were correlated with the electrical measurements made on MOS capacitors with Ru metal gates on HfO2 gate dielectric. The results indicated that the oxygen content at metal/high-k interface plays an important role in governing the effective work function of Ru on HfO2 gate dielectric.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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References

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