Package having redistribution layer structure with protective layer and method of fabricating the same

A package, comprising:

• a die;
• and
• a redistribution layer (RDL) structure electrically connected to the die, wherein the RDL structure comprises:
• a dielectric layer comprising a first dielectric material and a second dielectric material over the first dielectric material;
• a conductive feature electrically connected to the die, wherein the conductive feature comprises a plurality of first conductive patterns, and the plurality of first conductive patterns is disposed on and wholly above a top surface of the first dielectric material and embedded in the second dielectric material;
• a first seed layer sandwiched between a bottom surface of each first conductive pattern of the plurality of first conductive patterns and the top surface of the first dielectric material, wherein the first seed layer is in direct contact with and completely covers the entire bottom surface of each first conductive pattern of the plurality of first conductive patterns;
• and
• a first protective layer extending between two adjacent first conductive patterns and being in contact with the top surface of the first dielectric material, wherein the two adjacent first conductive patterns are electrically isolated by the first protective layer that extends over and covers sidewalls of the two adjacent first conductive patterns and sidewalls of the first seed layer.

A package structure, comprising:

• a die having a front side and a back side;
• an encapsulant laterally encapsulating a sidewall of the die;
• and
• a first redistribution layer (RDL) structure disposed over the front side of the die and the encapsulant, wherein the first RDL structure comprises:
• a dielectric layer comprising a first dielectric material and a second dielectric material over the first dielectric material;
• a conductive feature electrically connected to the die, wherein the conductive feature comprises a plurality of first conductive patterns, the plurality of first conductive patterns is disposed on and wholly above a top surface of the first dielectric material and embedded in the second dielectric material;
• and
• a first protective layer extending between two adjacent first conductive patterns and being in contact with the top surface of the first dielectric material, so as to form a U-shape in cross-section, wherein the first protective layer having a substantially same and uniform thickness to conformally covers sidewalls of the two adjacent first conductive patterns and the top surface of the first dielectric material,
• wherein the plurality of first conductive patterns extend on the top surface of the first dielectric material without extending into the die, and the first protective layer covers the sidewalls of plurality of first conductive patterns without extending to contact bottom surfaces of the plurality of first conductive patterns.