SIMS Analysis of Nickel-Silicon Multilayers
EMSL Project ID
2498
Abstract
Nickel monosilicide (NiSi) has been identified as a key contact material for next-generation VLSI technology. NiSi is conventionally prepared through the solid state reaction of a thin Ni film with exposed Si in the active device. Upon annealing, dinickel silicide forms prior to the formation of the desired nickel monosilicide, as is observed in bulk nickel-silicon diffusion couples. Research in our laboratory has focused on rational solid state synthesis using modulated elemental multilayers as reactants. When the modulation wavelength is below a system-specific critical thickness, moderate annealing of the multilayer will produce a homogenous amorphous intermediate. Further annealing typically produces a crystalline compound with a composition near that of the amorphous intermediate. We have used this synthetic strategy to prepare fine-grained nickel monosilicide films directly from modulated elemental multilayer precursors. We have also prepared multilayers with longer modulation wavelengths in which dinickel silicide is the first nucleated phase, as in bulk nickel-silicon diffusion couples. We have followed the course of the interfacial reactions using x-ray reflectivity (XRR) and grazing incidence x-ray diffraction to follow interdiffusion and nucleation in the multilayers. We expect that direct depth profiling by SIMS will complement the indirect depth profiles determined by XRR and provide clearer insight into the mechanisms which govern nucleation and first phase formation in these multilayers. We anticipate using these analyses in a publication in preparation for an applied physics journal. We also expect to gain further understanding into the nature of oxidation in these multilayers. In addition, we anticipate answering fundamental questions about the compatibility and comparability of SIMS and XRR for the characterization of modulated multilayers. Specifically, we have two groups of three samples prepared for SIMS analysis : the first group consists of three pieces of a nickel-silicon multilayer (52 at% nickel) with sixteen 5.7 nm Ni-Si bilayer subunits : (1) as deposited, (2) annealed to form dinickel silicide at the interfaces, (3) annealed to form nickel silicide. The second group consists of three pieces of a nickel-silicon multilayer (52 at% nickel) with sixteen 2.0 nm Ni-Si bilayer subunits : (1) as deposited, (2) annealed to form a homogenous amorphous Ni-Si intermediate, (3) annealed to form nickel silicide. In the first group of samples the reaction is observed to follow bulk diffusion couple behavior. In the second group of samples the reaction is observed to follow the reaction pathway described by our solid state synthetic technique. We expect that SIMS analysis coupled with our previously collected XRR analysis will enable us to describe in detail the differences in the respective reaction mechanisms.
Project Details
Project type
Exploratory Research
Start Date
2002-04-17
End Date
2003-04-22
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
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