Metal bump packaging structure and preparation method thereof

Abstract

The embodiment of the invention provides a metal bump packaging structure and a preparation method thereof, which relate to the technical field of semiconductor packaging. The metal bump packaging structure comprises a substrate chip, a conductive bonding pad, a protection layer, a metal conductive layer and a welding bump, wherein the surface of the protection layer is provided with a first step surface and a second step surface, the first step face and the second step face are connected through a slope, and at least one first drainage groove is formed in the slope. Through the arrangement of the first drainage grooves, liquid residues during etching of the metal conductive layer areas at the bottoms of the welding protrusions can be reduced more effectively, so that the problem that undercut openings are generated in the metal conductive layer areas at the bottoms of the welding protrusions is avoided, and meanwhile, the protection layer can have certain deformation allowance in the horizontal direction; and a buffering effect can be achieved. And meanwhile, the surface roughness of the protection layer can be increased by forming the first drainage groove, so that the bonding strength between the bottom filling glue and the protective layer is improved, and the structural stability of the product is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductor packaging, in particular to a metal bump packaging structure and a preparation method thereof. Background technique [0002] With the rapid development of the semiconductor industry, the flip-chip packaging structure is widely used in the semiconductor industry, and the flip-chip packaging uses bumps to electrically connect the chip and the substrate. The bump includes a copper pillar, a metal layer (UBM: under bumpmetalization), a protective layer (Polyimide), and a tin cap (Sn Cap). After the metal layer UBM is fabricated, the excess metal layer needs to be etched and removed. Because the polyimide material is extremely easy to absorb water, the etchant on the UBM sidewall at the bottom of the metal pillar remains, resulting in excessive corrosion undercut openings at the bottom of the copper pillar bump. When the bump chip is tested for reliability, the copper pillar bump exists drop pro...

AI Technical Summary

Problems solved by technology

The bump includes a copper pillar, a metal layer (UBM: under bumpmetalization), a protective layer (Polyimide), and a tin cap (Sn Cap). After the metal layer UBM is fabricated, the excess metal layer needs to be etched and removed. Because the polyimide material is extremely easy to absorb water, the etchant on the UBM sidewall at the bottom of the metal pillar remains, resulting in excessive corrosion undercut openings at the bottom of the copper pillar bump. When the bump chip is tested for reliability, the copper pillar bump exists drop problem

[0003] In addition, in the packaging process for flip-chip copper pillar bumps, as the distance between the flip-chip soldering and the substrate becomes smaller and smaller, underfill glue is often used to fill and protect the bottom of the flip-chip. , in order to increase the bonding strength between the underfill glue and the chip surface protection layer, plasma bombardment of the organic surface is often used to improve the roughness of the organic surface and improve the bonding strength of the underfill glue. The process is complex

However, if silicon nitride or silicon nitride is used as the protective layer, the plasma bombardment has a poor effect on the surface roughness, resulting in a decrease in the bonding strength between the underfill and the protective layer, which is not conducive to the stability of the product.

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