A method of manufacturing a semiconductor structure includes providing a substrate including a redistribution layer (RDL) disposed over the substrate, disposing a first patterned mask over the RDL, disposing a first conductive material over the RDL exposed from the first patterned mask to form a first conductive pillar, removing the first patterned mask, disposing a second patterned mask over the RDL, disposing a second conductive material over the RDL exposed from the second patterned mask to form a second conductive pillar, removing the second patterned mask, disposing a first die over the first conductive pillar, and disposing a second die over the second conductive pillar. A height of the second conductive pillar is substantially greater than a height of the first conductive pillar.