Packaging substrate including an underfill injection opening and methods of forming the same

A semiconductor structure comprising:

• an assembly comprising at least one semiconductor die and an interposer that comprises first interposer bonding pads and second interposer bonding pads;
• a packaging substrate comprising substrate bonding pads and including a first surface facing the assembly and having a first inner periphery and a first outer periphery, a second surface located on an opposite side of the first surface and having a second inner periphery and a second outer periphery, and at least one inner sidewall extending between the first inner periphery and the second inner periphery, wherein an area enclosed by the first inner periphery overlaps with an area of the second interposer bonding pads in a plan view;
• first solder material portions bonded to a respective one of the substrate bonding pads and to a respective one of the first interposer bonding pads;
• and
• at least one surface mount die bonded to the second interposer bonding pads through second solder material portions,
• wherein the interposer is interposed between the at least one semiconductor die and the packaging substrate.

A semiconductor structure comprising:

• an assembly including at least one semiconductor die and an interposer;
• a packaging substrate comprising substrate bonding pads, a first surface facing the assembly, a second surface located on an opposite side of the first surface, and an opening vertically extending between the first surface and the second surface;
• first solder material portions bonded to a respective one of the substrate bonding pads and to a respective one of first interposer bonding pads located on the interposer;
• and
• an underfill material portion comprising a horizontally-extending portion that laterally surrounds the first solder material portions and a vertically-extending portion that is located within the opening in the packaging substrate,
• wherein the interposer is interposed between the at least one semiconductor die and the packaging substrate.