Chip bump structure and method for forming the same

A chip bump structure formed on a substrate including at least one contact pad and a dielectric layer having at least one opening, the at least one opening exposing the at least one contact pad, the chip bump structure comprising:

• at least one elastic bump formed on the dielectric layer;
• at least one first metal layer covering both the at least one elastic bump and the at least one contact pad, and extending between the at least one elastic bump and the at least one contact pad;
• at least one second metal layer formed on a portion of the at least one first metal layer located on the top of the at least one elastic bump;
• and
• at least one solder ball formed on the at least one second metal layer and on the top of the at least one elastic bump.

A method for forming a chip bump structure, comprising the steps of:

• providing a substrate including at least one contact pad and a dielectric layer, the dielectric layer having at least one opening exposing the at least one contact pad;
• forming at least one elastic bump in the at least one opening, wherein the at least one elastic bump covers a central portion of the at least one contact pad;
• disposing a first metal layer on at least one elastic bump;
• electroplating a second metal layer on a portion of the first metal layer on the top of the at least one elastic bump;
• electroplating a solder material layer on the second metal layer;
• forming a patterned photoresist layer covering the solder material layer, a portion of the first metal layer that is on the at least one elastic bump, a portion of the first metal layer that is in the at least one opening, and a portion of the first metal layer that is in a peripheral area surrounding the opening;
• etching portions of the first metal layer that are not overlaid by the patterned photoresist layer;
• removing the patterned photoresist layer;
• and
• reflowing the solder material layer to obtain a solder ball.

A method for forming a chip bump structure, comprising the steps of:

• providing a substrate including at least one contact pad and a dielectric layer, the dielectric layer having at least one opening exposing the at least one contact pad;
• forming at least one elastic bump on the dielectric layer;
• disposing a first metal layer on at least one elastic bump;
• electroplating a second metal layer on a portion of the first metal layer on the top of the at least one elastic bump;
• electroplating a solder material layer on the second metal layer;
• forming a patterned photoresist layer covering the solder material layer, a portion of the first metal layer that is on the at least one elastic bump, a portion of the first metal layer that is on the at least one contact pad, and a portion of the first metal layer that extends between the at least one elastic bump and the at least one contact pad;
• etching portions of the first metal layer that are not overlaid by the patterned photoresist layer;
• removing the patterned photoresist layer;
• and
• reflowing the solder material layer to obtain a solder ball.