US Patent 11581284 Semiconductor package with under-bump metal structure

A semiconductor package includes a redistribution structure including an insulating layer and a redistribution layer on the insulating layer, and having a first surface and a second surface opposing the first surface, and an under-bump metal (UBM) structure including an UBM pad protruding from the first surface of the redistribution structure, and an UBM via penetrating through the insulating layer and connecting the redistribution layer and the UBM pad. A lower surface of the UBM via has a first area in contact with the UBM pad, and a second area having a step configuration relative to the first area and that extends outwardly of the first area.