Redistribution lines with protection layers and method forming same

A device comprising:

• a passivation layer;
• a redistribution line comprising a via portion extending into the passivation layer, and a line portion over and joining to the via portion, wherein the line portion comprises:
• a seed layer over the passivation layer, wherein the seed layer comprises first outer edges;
• a conductive material over the seed layer, wherein the conductive material comprises second outer edges;
• and
• a protection layer comprising:
• a top portion over and contacting the conductive material, wherein the top portion of the protection layer comprise third outer edges vertically offset from respective ones of the second outer edges;
• and
• a sidewall portion directly contacting one of the second outer edges of the conductive material;
• and
• a first dielectric layer on the first sidewall portion and the top portion of the protection layer.

A device comprising:

• a first dielectric layer;
• a redistribution line comprising a portion over the first dielectric layer, wherein the redistribution line comprises:
• a metal seed layer;
• a conductive feature over the metal seed layer, wherein the metal seed layer extends laterally beyond respective edges of the first conductive feature;
• and
• a protection layer comprising:
• a top portion over and contacting a first top surface of the conductive feature, wherein the top portion also extends laterally beyond the respective edges of the conductive feature;
• and
• a sidewall portion contacting a sidewall of the conductive feature to form a vertical interface;
• and
• a second dielectric layer contacting the redistribution line.