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Summary: Shocks in Ion Sputtering Sharpen
Steep Surface Features
H. Henry Chen,1
* Omar A. Urquidez,2
Stefan Ichim,2
L. Humberto Rodriquez,2
Michael P. Brenner,2
Michael J. Aziz2
.
We report a regime of ion beam sputtering that occurs for sufficiently steep
slopes. High slopes propagate over large distances without dissipating the
steepest features. Both the propagation velocity and the dynamically selected
slope are universal, independent of the details of the initial shape of the sur-
face. The resulting behavior can be understood as the propagation of a shock
front that self-selects a stable slope, as has been previously observed in thin-
film fluid flows. Experiments confirm predictions of the theory. An important
implication of the propagative behavior at high surface slopes is that a pat-
tern can be fabricated at a large length scale and, through uniform ion irradia-
tion, reduced to a smaller length scale while preserving, or even sharpening, the
sharpest features.
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