US Patent 7358616 Semiconductor stacked die/wafer configuration and packaging and method thereof

A reciprocal design symmetry allows stacked wafers or die on wafer to use identical designs or designs that vary only by a few layers (e.g. metal interconnect layers). Flipping or rotating one die or wafer allows the stacked die to have a reciprocal orientation with respect to each other which may be used to decrease the interconnect required between the vertically stacked die and or wafers. Flipping and/or rotating may also be used to improve heat dissipation when wafer and/or die are stacked. The stacked wafers or die may then be packaged.