Application of Fluorescence Correlation Spectroscopy in the Characterization of Particle Size Distributions of Colloidal Silica Abrasives Used in Chemical-Mechanical Planarization

2007 ◽  
Vol 991 ◽  
Author(s):  
Mungai Kamiti ◽  
Stacey Popadowski ◽  
Edward E. Remsen

ABSTRACTThe use of density gradient stabilized centrifugal sedimentation (disc centrifugation) for the characterization of abrasive particles in CMP slurries is reported. For slurries prepared with ceria and colloidal silica abrasives, the technique is demonstrated as capable of providing highly repeatable analyses of the abrasive's apparent particle size distribution (PSD). The addition of water soluble organic additives to the slurries is shown to produce large shifts in the apparent PSD relative to the PSD of the pure abrasive particles. Particle-additive interactions driving the shift in apparent PSD could not be interpreted with confidence due to the lack of accurate densities for particle-abrasive complexes formed in the slurry. To address this problem, sucrose density gradients prepared using H2O and D2O were tested as spin fluids of different densities to analyze a colloidal silica standard with a narrow PSD. Preliminary results comparing experimental disc centrifuge data with theoretical simulations of the disc sedimentation pattern suggest that this technique can potentially characterize both the particle diameter and density of abrasive particles in a CMP slurry.


Geoderma ◽  
2006 ◽  
Vol 134 (3-4) ◽  
pp. 373-385 ◽  
Author(s):  
J.G.V. Miranda ◽  
E. Montero ◽  
M.C. Alves ◽  
A. Paz González ◽  
E. Vidal Vázquez

Pteridines ◽  
2001 ◽  
Vol 12 (4) ◽  
pp. 147-153 ◽  
Author(s):  
U. Demel ◽  
Z. Foldes-Papp ◽  
D. Fuchs ◽  
G. P. Tilz

Abstract In the present investigation, fluorescence con-elation spectroscopy (FCS) was used to measure the molecular motion of the pteridine derivative neopterin. However, technical limitations in the present optical setup precluded the identification of ,single neopterin molecules. FCS measurements with a fluorophore were also can-ied out for comparison. Exemplified by rhodamine green, we have introduced a concept that allows the detection, identification and analysis of assays in solution at the single-molecule level in tenns of bulk concentration. This concept is based on FCS and Poisson distribution analysis of assay sensitivity. The molecules had not to be quantified in a more concentrated fonn, or in flow and trapping experiments. The study demonstrated an ultrasensitive, reliable, rapid and direct tool for analytics and diagnostics in solution. We discuss a possible application of our new concept in activation control of cell-mediated immunity via neopterin determination.


Sign in / Sign up

Export Citation Format

Share Document