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Characterization of Chemical Bonding in Low-K Dielectric Materials for Interconnect Isolation: A XAS and EELS Study

Published online by Cambridge University Press:  01 February 2011

Patrick Hoffmann ,
Dieter Schmeisser ,
Hans-Juergen Engelmann ,
Ehrenfried Zschech ,
Heiko Stegmann ,
Franz Himpsel  and
Jonathan Denlinger
Patrick Hoffmann
Affiliation:
Patrick.Hoffmann@tu-cottbus.de, Brandenburg Technical University of Cottbus, Chair of Applied Physics II, Konrad-Wachsmann-Allee 17, Cottbus, N/A, 03046, Germany, +49 (0)355 69-2998, +49 (0)355 69-3931
Dieter Schmeisser
Affiliation:
dsch@tu-cottbus.de, Brandenburg Technical University of Cottbus, Chair of Applied Physics II, Konrad-Wachsmann-Allee 17, Cottbus, N/A, 03046, Germany
Hans-Juergen Engelmann
Affiliation:
hans-juergen.engelmann@AMD.COM, AMD Saxony LLC & Co KG, Dresden, N/A, N/A, Germany
Ehrenfried Zschech
Affiliation:
ehrenfried.zschech@amd.com, AMD Saxony LLC & Co KG, Dresden, N/A, N/A, Germany
Heiko Stegmann
Affiliation:
h.stegmann@online.de, Carl Zeiss NTS GmbH, Oberkochen, N/A, N/A, Germany
Franz Himpsel
Affiliation:
h.stegmann@online.de, Carl Zeiss NTS GmbH, Oberkochen, N/A, N/A, Germany
Jonathan Denlinger
Affiliation:
fhimpsel@wisc.edu, University of Wisconsin / Madison, Madison, Wisconsin, 53706, United States
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Abstract

The use of low dielectric constant materials in the on-chip interconnect process reduces interconnect delay, power dissipation and crosstalk noise. To achieve the requirements of the ITRS for 2007-2009 minimal sidewall damage from etch, ash or cleans is required. In chemical vapor deposited (CVD) organo-silicate glass (OSG) which are used as intermetal dielectric (IMD) materials the substitution of oxygen in SiO2 by methyl groups (-CH3) reduces the permit-tivity significantly (from 4.0 in SiO2 to 2.6-3.3 in the OSG), since the electronic polarizability is lower for Si-C bonds than for Si-O bonds.

However, plasma processing for resist stripping, trench etching and post-etch cleaning removes C and H containing molecular groups from the near-surface layer of OSG. Therefore, compositional analysis and chemical bonding characterization of structured IMD films with nanometer resolution is necessary for process optimization.

OSG thin films as-deposited and after plasma treatment are studied using X-ray absorp-tion spectroscopy (XAS) and electron energy loss spectroscopy (EELS). In both techniques, the fine structure near the C1s absorption or energy loss edge, respectively, allows to identify C-H, C-C, and C-O bonds. This gives the opportunity to differentiate between individual low-k mate-rials and their modifications. The O1s signal is less selective to individual bonds. XAS spectra have been recorded for non-patterned films and EELS spectra for patterned structures. The chemical bonding is compared for as-deposited and plasma-treated low-k materials. The Fluo-rescence Yield (FY) and the Total Electron Yield (TEY) recorded while XAS measurement are compared. Examination of the C 1s near-edge structures reveal a modified bonding of the re-maining C atoms in the plasma-treated sample regions.

Keywords

dielectricx-ray fluorescenceelectron energy loss spectroscopy (EELS)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 914: Symposium F – Materials, Technology and Reliability of Low-k Dielectrics and Copper Interconnects , 2006 , 0914-F01-08
Copyright
Copyright © Materials Research Society 2006

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