Flat-top bumping structure and preparation method

A method of making an electrical contact bump structure on a substrate comprising:

• providing a substrate having a bond pad, and a passivation layer overlying a portion of the substrate and wherein the passivation layer includes an opening therein exposing a portion of the bond pad, and wherein the passivation layer has a raised portion overlying the bond pad;
• forming a sacrificial blanket having an opening therethrough that in cross-section has an inverted T-shape over the substrate so that the opening in the sacrificial blanket is aligned with the bond pad;
• depositing an under bump metallurgy through the opening in the sacrificial blanket;
• depositing an electrically conductive material into the opening in the sacrificial blanket so that the electrically conductive material overlies at least a portion of the under bump metallurgy including the portion of the under bump metallurgy overlying the raised portion of the passivation layer and so that a bump structure is formed having a flat-top engagement surface that is free of any raised portion.

A method comprising:

• providing a substrate having a bond pad, and a passivation layer overlying a portion of the substrate and wherein the passivation layer includes an opening therein exposing a portion of the bond pad, and wherein the passivation layer has a raised portion overlying the bond pad, and an under bump metallurgy at least over the exposed portion of the bond pad and over at least the portion of the raised portion of the passivation layer overlying the bond pad;
• forming a first photoresist layer over the substrate including the passivation layer, the under bump metallurgy and the bond pad;
• over exposing a portion of the first photoresist layer using a large proximity gap on a mask aligner;
• forming a second photoresist layer over the first photoresist layer, and under exposing a portion of the second photoresist layer;
• developing the first photoresist layer and second photoresist layer and removing the exposed portions thereof to provide an opening in the first photoresist layer and the second photoresist layer that has in cross-section an inverted T-shape.

A method comprising:

• providing a substrate having a bond pad, and a passivation layer overlying a portion of the substrate and wherein the passivation layer includes an opening therein exposing a portion of the bond pad, and wherein the passivation layer has a raised portion overlying the bond pad, and an under bump metallurgy over at least the exposed portion of the bond pad and over at least a portion of the raised portion of the passivation layer overlying the bond pad;
• forming a first photoresist layer over the substrate, the passivation layer, and the under bump metallurgy;
• exposing the first photoresist layer to ultraviolet light without a mask;
• forming a second photoresist layer over the first photoresist layer, and selectively exposing a portion of the second photoresist layer to ultraviolet light;
• developing the first photoresist layer and second photoresist layer and etching the first photoresist layer and second photoresist layer to provide an under cut of the first photoresist layer so that an opening is provided through the first photoresist layer and the second photoresist layer that in cross-section has an inverted T-shape.

A method comprising:

• providing a substrate having a bond pad, and a passivation layer overlying a portion of the substrate and wherein the passivation layer includes an opening therein exposing a portion of the bond pad, and wherein the passivation layer has a raised portion overlying the bond pad, and an under bump metallurgy over at least the exposed portion of the bond pad and over at least a portion of the raised portion of the passivation layer overlying the bond pad;
• forming a non-photosensitive layer over the substrate, including the passivation layer and the under bump metallurgy;
• forming a photoresist layer over the non-photosensitive layer and exposing a portion of the photoresist layer to ultraviolet light;
• developing the photoresist layer and etching the photoresist layer and the non-photosensitive layer with an under cut of the non-photosensitive layer to provide an opening into the photoresist layer and the non-photosensitive layer that in cross-section has an inverted T-shape.