Redistribution structure with warpage tuning layer

A method of forming a semiconductor device, the method comprising:

• forming a redistribution structure over a carrier, comprising:
• forming a dielectric layer over the carrier;
• forming a conductive line extending along an upper surface of the dielectric layer distal from the carrier;
• covering an upper surface of the conductive line distal from the carrier with a warpage tuning material, wherein the upper surface of the dielectric layer is exposed by the warpage tuning material, wherein a first coefficient of thermal expansion (CTE) of the conductive line is different from a second CTE of the warpage tuning material;
• and
• forming a via over and electrically coupled to the conductive line;
• forming conductive bumps over and electrically coupled to a first side of the redistribution structure;
• and
• bonding a die to the conductive bumps.

A method of forming a semiconductor device, the method comprising:

• forming a redistribution structure over a carrier, comprising:
• forming a dielectric layer over the carrier;
• forming a conductive line extending along an upper surface of the dielectric layer distal from the carrier;
• forming a warpage tuning material on an upper surface of the conductive line distal from the carrier, wherein the warpage tuning material covers the upper surface of the conductive line and exposes the upper surface of the dielectric layer, wherein a coefficient of thermal expansion (CTE) of the warpage tuning material is different from that of the conductive line;
• removing a portion of the warpage tuning material from the upper surface of the conductive line, wherein after the removing, a remaining portion of the warpage tuning material forms a warpage tuning layer that partially covers the upper surface of the conductive line;
• and
• forming a via over and electrically coupled to the conductive line;
• forming a conductive bump over and electrically coupled to the via;
• and
• bonding a die to the conductive bump.