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Channel Strain Analysis in Damascene-gate pMOSFETs on Si (100) and (110) Substrate by Conventional and Cross-sectional Raman Spectroscopy

Published online by Cambridge University Press:  31 January 2011

Munehisa Takei
Affiliation:
[email protected], Meiji University, School of Science and Technology, Kawasaki, Japan
Daisuke Kosemura
Affiliation:
[email protected], Meiji University, School of Science and Technology, Kawasaki, Japan
Kohki Nagata
Affiliation:
[email protected], Meiji University, School of Science and Technology, Kawasaki, Japan
Hiroaki Akamatsu
Affiliation:
[email protected], Meiji University, School of Science and Technology, Kawasaki, Japan
Satoru Mayuzumi
Affiliation:
[email protected], Sony Corporation, Atsugi, Japan
Shinya Yamakawa
Affiliation:
[email protected], Sony Corporation, Atsugi, Japan
Hitoshi Wakabayashi
Affiliation:
[email protected], Sony Corporation, Atsugi, Japan
Atsushi Ogura
Affiliation:
[email protected], Meiji University, School of Science and Technology, Kawasaki, Japan
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Abstract

Channel strain in damascene gate pMOSFETs with compressive stress liner (c-SL) and embedded SiGe (eSiGe) were studied by micro-Raman spectroscopy with a quasi-line-shape UV excitation (λ=363.8nm). The channel strain profiles were obtained by the conventional mea-surement from the surface after dummy gate removal. The compressive strains at the channel edges were larger than that at the channel center for the relatively long gate length (Lgate). As the Lgate became smaller, although it became hard to recognize the strain profile, the compres-sive strain at the channel center increased by the superposition of the strain at the channel edges. However, channel strain disappeared in the measurement data for the channel length less than 160 nm. Thus, we extended the laser exposure time from 10 to 40 minutes to extract the channel strain component from obtained Raman spectra. The Raman peaks consisted of two or three peaks for the Lgate less than 160 nm. By multi peak fitting, we have succeeded in measuring the extremely large stress of - 2.4 GPa in the channel of Lgate = 30 nm pMOSFET. We also per-formed the cross-sectional measurements for the samples before and after metal-gate/high-k gate stack formation. Channel strain profiles were obtained similar to those by the conventional mea-surement. Extremely high device performance can be clearly explained by the compressive stress derived from the Raman measurements both in the Lgate dependence and eSiGe effect. We also demonstrated that Raman spectroscopy using cross-sectional measurement can evaluate the channel strain even in the MOSFETs after gate stack formation.

Type
Research Article
Copyright
Copyright © Materials Research Society 2010

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