Method for forming solder bump

Abstract

The invention provides a method for forming a solder bump. The method comprises the following steps of: forming a heat resistant metal layer and a metal wetting layer on a pad and a passivation layer of a chip in sequence; forming a photoresist on the metal wetting layer, wherein the photoresist is provided with an opening to expose the metal wetting layer above the pad of the chip; forming an adhesion layer and a barrier layer on the metal wetting layer in the opening in sequence; forming solder paste on the barrier layer; removing the photoresist; etching the heat resistant metal layer and the metal wetting layer on the passivation layer until the passivation layer is exposed; and ensuring the solder paste to reflow to form a pillar bump. The method has the effect of improving the electrical property and reliability of the solder bump and is suitable for chip scale package with the requirements of fine pad pitch and multiple output functions.

Description

technical field [0001] The invention relates to the field of semiconductor device packaging, in particular to methods for forming flip-chip welding, solder bumps, and wafer-level chip scale packages (Wafer Level chip Scale Package, WLCSP). Background technique [0002] In recent years, since the microcircuit manufacturing of chips is developing toward high integration, the chip packaging also needs to develop in the direction of high power, high density, thinness and miniaturization. Chip packaging means that after the chip is manufactured, the chip is wrapped in plastic or ceramic materials to protect the chip from external moisture and mechanical damage. The main functions of the chip package are power distribution, signal distribution, heat dissipation and protection support. [0003] Since today's electronic products are required to be light, thin, small and highly integrated, the fabrication of integrated circuits will be miniaturized, resulting in an increase in the n...

AI Technical Summary

Problems solved by technology

[0006] In the process of forming wafer-level chip size packaging in the prior art, since the solder bump material is directly in contact with the metal wetting layer, the copper in the metal wetting layer easily diffuses into the tin of the solder bump to form a copper-tin alloy, which affects the soldering quality

At the same time, before the solder is formed on the metal wetting layer, the exposed wetting layer is easily oxidized, which reduces the performance and reliability of the subsequently formed solder bumps

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