The semiconductor package has a metal layer, a first dielectric layer formed on a metal layer, and an opening formed through the first dielectric layer to expose a part of the metal layer. The bump structure has an under bump metallurgy (hereinafter UBM), a first buffer layer and a metal bump. The UBM is formed on the first part of the metal layer, a sidewall of the opening and a top surface of the first dielectric layer. The first buffer layer is formed between a part of the UBM corresponding to the top surface of the first dielectric layer and the top surface of the first dielectric layer. The metal bump is formed on the UBM. Therefore, the first buffer layer effectively absorbs a thermal stress to avoid cracks generated in the bump structure after the bonding step.

The semiconductor package has a metal layer, a first dielectric layer formed on a metal layer, and an opening formed through the first dielectric layer to expose a part of the metal layer. The bump structure has an under bump metallurgy (hereinafter UBM), a first buffer layer and a metal bump. The UBM is formed on the first part of the metal layer, a sidewall of the opening and a top surface of the first dielectric layer. The first buffer layer is formed between a part of the UBM corresponding to the top surface of the first dielectric layer and the top surface of the first dielectric layer. The metal bump is formed on the UBM. Therefore, the first buffer layer effectively absorbs a thermal stress to avoid cracks generated in the bump structure after the bonding step.

A method includes disposing a patterned conductor layer directly on mold material in a fan-out space adjacent to an integrated circuit (IC) chip in a reconstituted wafer. The patterned conductor layer is limited or confined in spatial extent to the fan-out space. The method further includes configuring the patterned conductor layer disposed directly on mold material as a first redistribution layer (RDL) in a fan-out package of the IC chip to carry signals associated with at least one input-output (I/O) contact on the chip.

A semiconductor package includes a connection member having a first surface and a second surface opposing each other and including a first redistribution layer on the second surface and at least one second redistribution layer on a level different from a level of the first redistribution layer; a semiconductor chip on the first surface of the connection member; a passivation layer on the second surface of the connection member, and including openings; UBM layers connected to the first redistribution layer through the openings; and electrical connection structures on UBM layers. An interface between the passivation layer and the UBM layers has a first unevenness surface, an interface between the passivation layer and the first redistribution layer has a second unevenness surface, connected to the first unevenness surface, and the second unevenness surface has a surface roughness greater than a surface roughness of the second redistribution layer.

A semiconductor package includes a connection member having a first surface and a second surface opposing each other and including a first redistribution layer on the second surface and at least one second redistribution layer on a level different from a level of the first redistribution layer; a semiconductor chip on the first surface of the connection member; a passivation layer on the second surface of the connection member, and including openings; UBM layers connected to the first redistribution layer through the openings; and electrical connection structures on UBM layers. An interface between the passivation layer and the UBM layers has a first unevenness surface, an interface between the passivation layer and the first redistribution layer has a second unevenness surface, connected to the first unevenness surface, and the second unevenness surface has a surface roughness greater than a surface roughness of the second redistribution layer.