A system for thinning a layer on a substrate without damaging a delicate underlying
layer in the substrate. The system includes means for mechanically eroding the
layer on the substrate, and means for electropolishing the layer on the substrate.
In this manner, portions of the layer that cannot be removed by electropolishing
can be removed by the mechanical erosion. However, electropolishing can preferentially
be used on some portions of the layer so that unnecessary mechanical stresses can
be avoided. Thus, the system imparts less mechanical stress to the substrate during
the removal of the layer, and the delicate underlying layer receives less damage
during the process, and preferably no damage whatsoever.
