Interconnect structure and method of fabricating same

A method comprising:

• forming a passivation layer over a semiconductor substrate, wherein a metal pad is embedded in the passivation layer and exposed through an opening of the passivation layer;
• depositing a first polymer layer on the passivation layer;
• forming a redistribution layer over the first polymer layer;
• mounting a bump over the redistribution layer and electrically coupled to the redistribution layer;
• forming a liquid molding compound layer over the passivation layer, wherein the bump is embedded in the liquid molding compound layer;
• and
• pressing the liquid molding compound layer until a portion of a release film is lower than a top surface of the bump.

A device comprising:

• an interconnect structure over a substrate;
• a passivation layer over the interconnect structure, wherein a metal pad is embedded in the passivation layer and exposed through an opening of the passivation layer;
• a first dielectric layer formed over the passivation layer;
• a post passivation interconnect structure formed in the first dielectric layer, wherein the post passivation interconnect structure is directly connected to the metal pad;
• a bump directly mounted to the post passivation interconnect structure, the bump being a sphere, wherein the bump comprises:
• a solder ball;
• a metal coating layer formed over the solder ball, the metal coating layer having a thickness in a range from about 2 um to about 20 um;
• and
• a solder layer formed over the metal coating layer, the solder layer physically contacting the post passivation interconnect structure, the post passivation interconnect structure contacting the solder layer having a first material composition, the post passivation interconnect structure in the first dielectric layer having the first material composition;
• a second dielectric layer physically contacting the post passivation interconnect structure and the first dielectric layer, the second dielectric layer surrounding and physically contacting a lower portion of the bump;
• a molding compound layer formed over the second dielectric layer, wherein the molding compound layer comprises:
• a flat portion, and wherein a bottom portion of the bump is embedded in the flat portion;
• and
• a protruding portion, and wherein a middle portion of the bump is surrounded by the protruding portion , and wherein the protruding portion of the molding compound layer and the flat portion of the molding compound layer form an angle in a range from about 10 degrees to about 60 degrees.

A method comprising:

• forming a passivation layer over a semiconductor substrate, wherein a metal pad is embedded in the passivation layer and exposed through an opening of the passivation layer;
• depositing a first polymer layer on the passivation layer;
• forming a redistribution layer over the first polymer layer;
• mounting a bump over the redistribution layer and electrically coupled to the redistribution layer;
• forming a molding compound layer over the passivation layer, wherein the bump is embedded in the molding compound layer;
• and
• pressing the molding compound layer until a portion of a release film is lower than a top surface of the bump, wherein after the pressing the molding compound layer, the molding compound layer has a protruding portion proximate and surrounding the bump, the protruding portion being surrounding by a flat portion of the molding compound layer.