Method of making a bump on a substrate using multiple photoresist layers

A method of making a bump on a semiconductor device comprising:

• providing a semiconductor device having a contact pad and having an upper passivation layer and an opening formed in the passivation layer exposing a portion of the contact pad;
• depositing an under bump metallurgy over the upper passivation layer and the contact pad;
• depositing a first photoresist layer in a liquid state over the under bump metallurgy;
• solidifying the first photoresist layer so that the first photoresist layer adheres to the under bump metallurgy without any gaps between the first photoresist layer and the under bump metallurgy;
• depositing a second photoresist layer over the first photoresist layer, and wherein the second photoresist layer comprises a dry film photoresist;
• selectively developing a portion of the first and second photoresist layers leaving other portions of the first and second photoresist layers undeveloped;
• removing the undeveloped portions of the second photoresist layer;
• removing the undeveloped portions of the first photoresist layer, wherein the removal of the undeveloped portions of the first and second photoresist layers provides an opening in the photoresist layers down to the under bump metallurgy aligned with the contact pad;
• depositing an electrically conductive material into the opening formed in the photoresist layers and overlying the under bump metallurgy and aligned with the contact pad;
• removing the developed portions of the second photoresist layer;
• removing the developed portions of the first photoresist layer;
• and
• reflowing the electrically conductive material to provide a bump on the semiconductor device.