Thin film characterization by total reflection x-ray fluorescence

Sensitive and accurate characterization of films thinner than a few nm used in nanoelectronics represents a challenge for many conventional production metrology tools. With capabilities in the 10 10 at/cm 2, methods usually dedicated to contamination analysis appear promising, especially Total-refle...

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Published inSpectrochimica acta. Part B: Atomic spectroscopy Vol. 63; no. 12; pp. 1365 - 1369
Main Authors Danel, Adrien, Nolot, Emmanuel, Veillerot, Marc, Olivier, Ségolène, Decorps, Tifenn, Calvo-Muñoz, Maria-Luisa, Hartmann, Jean-Michel, Lhostis, Sandrine, Kohno, Hiroshi, Yamagami, Motoyuki, Geoffroy, Charles
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.12.2008
Elsevier
Subjects
Chemical Sciences
Composition analysis
Material chemistry
Silicon wafer
Thin film
TXRF
Composition analysis
Silicon wafer
TXRF
Thin film
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Summary:Sensitive and accurate characterization of films thinner than a few nm used in nanoelectronics represents a challenge for many conventional production metrology tools. With capabilities in the 10 10 at/cm 2, methods usually dedicated to contamination analysis appear promising, especially Total-reflection X-Ray Fluorescence (TXRF). This study shows that under usual configuration for contamination analysis, with incident angle smaller than the critical angle of the substrate, TXRF signal saturation occurs very rapidly for dense films (below 0.5 nm for HfO 2 films on Si wafers using a 9.67 keV excitation at 0.5°). Increasing the incident angle, the range of linear results can be extended, but on the other hand, the TXRF sensitivity is degraded because of a strong increase of the measurement dead time. On HfO 2 films grown on Si wafers, an incident angle of 0.32° corresponding to a dead time of 95% was used to achieve linear analysis up to 2 nm. Composition analysis by TXRF, and especially the detection of minor elements into thin films, requires the use of a specific incident angle to optimize sensitivity. Although quantitative analyses might require specific calibration, this work shows on Co–based films that the ratio between minor elements (W, P, Mo) and Co taking into account their relative sensitivity factors is a good direct reading of the composition.
ISSN:0584-8547
1873-3565
DOI:10.1016/j.sab.2008.10.024