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11th Edition: Comparing Contact and Non-Contact Technology for Post-CMP Cleaning |
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Feb 03, 2005 at 04:21 PM |
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KATRINA MIKHAYLICHENKO & MIKE RAVKIN, Lam Research Corp., Fremont, CA, USA
DAVE STEIN & DALE HETHERINGTON, Sandia National Laboratory, Albuquerque, NM, USA ABSTRACT
Lam
Research and Sandia National Laboratory have conducted studies that
compare the cleaning capabilities of non-contact megasonic cleaning
with contact cleaning that uses brush scrubbing. We found that
partially planarised features are far more difficult to clean than
polished blanket dielectric or metal surfaces. Features with larger
step heights and/or small horizontal dimensions may efficiently trap
slurry and are, of course, difficult to clean. To investigate the
effect of topography size and aspect ratio on the relative cleaning
efficiency of spin-rinse-dry (SRD), megasonic, and brush scrubbing
techniques, special masks with topography of variable size and aspect
ratio were developed.
Trenches, holes, and corners from 0.6 to 4.0
microns in size with aspect ratio changing from 1:1 to 4:1 were etched
in PETEOS film. Two groups of wafers were then used for the tests.
Group I wafers were dipped in fumed silica, colloidal silica or Al2O3
slurry and cleaned using either a megasonic cleaning or a brush
scrubber. Group II wafers were polished with the same slurries to
remove various amounts of material and then cleaned using the same tool
sets. In this paper we present the results obtained with different
cleaning parameters and chemicals. Our results indicate that it is
extremely difficult to remove slurry from deep features after CMP
regardless of the cleaning technique. In conclusion, we show that both
the step height and the horizontal dimension of the feature are crucial
to the cleaning capability of a specific cleaning technique.
 Comparing Contact and Non-Contact Technology for Post-CMP Cleaning
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Wafer Processing 
