Mechanisms for forming copper pillar bumps
First Claim
1. A bump structure on a substrate, comprising:
- a composite conductive layer embedded in the substrate, wherein the composite conductive layer includes a protective conductive layer over a base conductive layer, and wherein the protective conductive layer is made of a material less likely to be oxidized in presence of air or water than a material for the base conductive layer;
a dielectric layer over the composite conductive layer, wherein the protective conductive layer positioned to separate the dielectric layer from the base conductive layer;
a polymer layer over the dielectric layer; and
a metal bump, wherein the metal bump fills a second opening of a photoresist layer, wherein the second opening is formed above a first opening created in the polymer layer to make contact with the protective conductive layer of the composite conductive layer.
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Abstract
The mechanism of forming a metal bump structure described above resolves the delamination issues between a conductive layer on a substrate and a metal bump connected to the conductive layer. The conductive layer can be a metal pad, a post passivation interconnect (PPI) layer, or a top metal layer. By performing an in-situ deposition of a protective conductive layer over the conductive layer (or base conductive layer), the under bump metallurgy (UBM) layer of the metal bump adheres better to the conductive layer and reduces the occurrence of interfacial delamination. In some embodiments, a copper diffusion barrier sub-layer in the UBM layer can be removed. In some other embodiments, the UBM layer is not needed if the metal bump is deposited by a non-plating process and the metal bump is not made of copper.
185 Citations
25 Claims
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1. A bump structure on a substrate, comprising:
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a composite conductive layer embedded in the substrate, wherein the composite conductive layer includes a protective conductive layer over a base conductive layer, and wherein the protective conductive layer is made of a material less likely to be oxidized in presence of air or water than a material for the base conductive layer; a dielectric layer over the composite conductive layer, wherein the protective conductive layer positioned to separate the dielectric layer from the base conductive layer; a polymer layer over the dielectric layer; and a metal bump, wherein the metal bump fills a second opening of a photoresist layer, wherein the second opening is formed above a first opening created in the polymer layer to make contact with the protective conductive layer of the composite conductive layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A bump structure on a substrate, comprising:
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a composite conductive layer embedded in the substrate, wherein the composite conductive layer includes a protective conductive layer over a base conductive layer, and wherein the protective conductive layer is made of a material less likely to be oxidized in presence of air or water than a material for the base conductive layer; a dielectric layer over the composite conductive layer; a polymer layer over the dielectric layer; a copper bump, wherein the copper bump fills a second opening of a photoresist layer, wherein the second opening is formed above a first opening created in the polymer layer to make contact with the protective conductive layer of the composite conductive layer, and wherein the copper bump includes an under bump metallurgy (UBM) layer lining a surface of the first opening and an interface between the polymer layer and the photoresist layer, and the copper bump extends into the first opening. - View Dependent Claims (16, 17, 18)
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19. An integrated circuit device, comprising:
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a substrate; a composite conductive layer embedded in the substrate, the composite conductive layer comprising; a base conductive layer; and a protective conductive layer over the base conductive layer, the protective conductive layer having a characteristic of oxidation rate slower than that of the base conductive layer in presence of air or water; a dielectric layer over the composite conductive layer and having a first opening defined therein to expose a first portion of an upper surface of the protective conductive layer; a polymer over the dielectric layer and having a second opening defined therein to expose a second portion of the upper surface of the protective conductive layer, the second portion being smaller than the first portion; and a bump structure at least partially in the second opening, the bump structure being positioned over the polymer layer and the exposed second portion of the upper surface of the protective conductive layer. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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Specification