Three-dimensional structures are provided which improve manufacturing
yield for certain structures in semiconductor devices. The
three-dimensional structures take into account the interaction between an
upper layer and a lower layer where the lower layer has a tendency to
form a non-planar surface due to its design. Accordingly, design changes
are performed to make structures more likely to function, either by
forming a more planar surface on the lower layer or by compensating in
the upper layer for the lack of planarity. The changes to improve
manufacturing yield are made at the design stage rather than at the
fabrication stage.