Polymer layers embedded with metal pads for heat dissipation

A method, comprising:

• forming an interconnect structure comprising conductive lines, conductive vias, and dielectric layers, an uppermost dielectric layer of the dielectric layers having a first dielectric constant;
• depositing a first passivation layer over the interconnect structure, the first passivation layer having a second dielectric constant greater than the first dielectric constant;
• forming a first metal pad through and over the first passivation layer;
• depositing a first polymer layer over the first passivation layer;
• forming a metal pillar over the first metal pad and within the first polymer layer;
• forming a second polymer layer over the first polymer layer;
• patterning a first opening, a second opening, and a third opening in the second polymer layer, the first opening having a first diameter, the second opening having a second diameter different from the first diameter;
• and
• plating a first via in the first opening, a second metal pad in the second opening, and a third metal pad in the third opening.

A method, comprising:

• forming an interconnect structure over a substrate;
• forming a first conductive feature and a second conductive feature over and electrically connected to the interconnect structure;
• depositing a first polymer layer over the first conductive feature and the second conductive feature;
• patterning to form first openings in the first polymer layer;
• forming a first redistribution structure, a second redistribution structure, and a first dummy metal pad in the first openings, wherein the first redistribution structure and the second redistribution structure are formed of a conductive material;
• depositing a second polymer layer over the first polymer layer, wherein the first redistribution structure and the second redistribution structure have a first height and the first dummy metal pad has a second height, the first height being greater than the second height;
• and
• forming a first electrical connector and a second electrical connector over the second polymer layer.