3D packages and methods for forming the same

A method comprising:

• forming a conductive pad in a first substrate;
• depositing a passivation layer over the conductive pad;
• embedding pad connectors in the passivation layer;
• forming an interconnecting structure over the pad connectors and the conductive pad, the forming the interconnect structure comprising:
• depositing a first dielectric layer over the passivation layer;
• forming first openings in the first dielectric layer;
• filling the first openings to form first metal lines;
• depositing a second dielectric layer over the first dielectric layer;
• forming second openings in the second dielectric layer, the second openings exposing portions of the first metal lines;
• and
• filling the second openings to form vias and second metal lines, the vias electrically coupling the first metal lines to the second metal lines;
• bonding a die to a first side of the interconnecting structure;
• and
• etching the first substrate from a second side of the interconnecting structure, the etching exposing the conductive pad.

A method comprising:

• forming a recess in a first substrate;
• forming a conductive pad in the recess, a top surface of the conductive pad being level with an upper surface of the first substrate;
• depositing a first passivation layer over the conductive pad;
• embedding a pad connector in the first passivation layer, a first and second surface of the pad connector being level with the first passivation layer;
• depositing a first dielectric layer over the first passivation layer;
• embedding a first metal line in the first dielectric layer;
• the first metal line having a third surface being level with the first dielectric layer;
• depositing a second dielectric layer over the first dielectric layer;
• embedding a second metal line and vias in the second dielectric layer, the vias being in contact with the first metal line, the second metal line having a fourth surface being level with the second dielectric layer;
• depositing a second passivation layer over the second metal line;
• forming an underbump metallurgy (UBM) in the second passivation layer;
• etching the first substrate to expose a bottom surface of the conductive pad, the bottom surface being opposite the top surface;
• and
• attaching a first die to the bottom surface of the conductive pad.