Abstract: A coil inductor includes a plurality of conductive coils stacking in a first direction. The coil inductor includes a topmost conductive coil including a first portion extending in a second direction perpendicular to the first direction and a second portion extending in the first direction, a bottommost conductive coil including a third portion extending in the second direction and a fourth portion extending in the first direction, and at least one intermediate conductive coil extending in the second direction and disposed between the topmost conductive coil and the bottommost conductive coil.