A semiconductor package includes a semiconductor chip including a semiconductor substrate and a plurality of cell transistors arranged on the semiconductor substrate. Channel regions of the cell transistors have channel lengths that extend in a first direction, and the package further includes a supporting substrate having an upper surface on which the semiconductor chip is affixed. The supporting substrate is configured to bend in response to a temperature increase in a manner that applies a tensile stress to the channel regions of the semiconductor chip in the first direction. Related methods are also disclosed.