Method for forming bumps

Abstract

The invention relates to a method for forming bumps, which comprises the following steps of: providing a semiconductor substrate, wherein a metal cushion layer and a passivation layer are formed on the semiconductor substrate, and the metal cushion layer is embedded into the passivation layer and is exposed through an opening on the passivation layer; sequentially forming a metal shielding layer and an under bump metal layer on the metal cushion layer in the opening of the passivation layer, wherein the under bump metal layer comprises a metal nickel layer; putting the semiconductor substrate into hydrogen ion or hydroxyl ion-containing electrolytic cell solution; reacting by using an applied electric field to treat the metal nickel layer in the under bump metal layer; and forming the bumps on the under bump metal layer. The method eliminates cavities formed in the subsequent bumps, ensures that all bumps have uniform size, avoids short circuits and open circuits, and improves packaging quality.

Description

technical field [0001] The invention relates to the field of manufacturing semiconductor devices, in particular to a method for manufacturing bumps. Background technique [0002] With the continuous development of integrated circuit technology, electronic products are increasingly developing in the direction of miniaturization, intelligence, high performance and high reliability. The integrated circuit packaging not only directly affects the performance of integrated circuits, electronic modules and even the whole machine, but also restricts the miniaturization, low cost and reliability of the entire electronic system. With the gradual reduction of the size of the integrated circuit chip and the continuous improvement of the integration level, the electronic industry has put forward higher and higher requirements for the integrated circuit packaging technology. [0003] Flip chip (flip chip) technology is through the solder balls formed on the surface of the chip, so that t...

AI Technical Summary

Problems solved by technology

[0007] In the existing process of forming bumps, due to the surface of the amorphous metal layer, it is easy to form a local uneven metal oxide layer

At present, when removing oxidized metal, local uneven surface defects will be formed

It will cause depressions in part of the surface of the metal nickel layer in the under bump metal layer or on the surface of the metal pad layer, and then continue to the interface between the metal nickel layer in the under bump metal layer and the tin-lead alloy; Hydrogen molecules or other gas molecules, in the process of subsequent reflow to form bumps, expand due to the influence of temperature rise, forming cavities in the bumps, increasing the area of ​​the bumps (such as Figure 4 As shown in 10), and then there may be a short circuit between the bumps or an open circuit between the bumps, which will affect the quality of the package

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