Method for forming solder bumps of increased height

A method of forming solder bumps of improved height, comprising:

• providing a semiconductor substrate having at least one contact pad and an upper passivation layer having at least one opening formed therein exposing a portion of the contact pad;
• forming a layer of Under Bump Metal (UBM) above the passivation layer and the contact pad;
• providing a first light sensitive layer above the UBM layer, wherein the first light sensitive layer has at least one first opening pattern region therein formed by a first exposure;
• providing a second light sensitive layer above the first light sensitive layer, wherein the second light sensitive layer has at least one second opening pattern region therein formed by a second exposure;
• developing the second and first light sensitive layers to remove the at least one first opening pattern region and the at least one second pattern region and respectively form at least one second opening and at least one first opening therein at the same time;
• filling a solder material in the at least one first opening and filling the solder material substantially in the at least one second opening;
• removing the first and second light sensitive layers;
• and
• reflowing the solder material to create a solder ball;
• wherein the step of providing the second light sensitive layer comprises:
• forming the second light sensitive layer above the first light sensitive layer after the first light sensitive layer is defined with the one first opening pattern region;
• and
• performing the second exposure to define on the second light sensitive layer the at least one second opening pattern region.