Columnar bump packaging process

Abstract

A columnar bump packaging process comprises the following steps: forming lower metal bump layers on a welding pad and a passivation layer of a chip; forming photoresist on the lower metal bump layers, wherein the photoresist is provided with an opening so as to expose the lower metal bump layer above the welding pad of the chip; forming a copper column on the lower metal bump layer in the opening; forming a welding bump on the copper column; removing the photoresist; etching the lower metal bump layer on the passivation layer till the passivation layer is exposed; forming an oxide layer on the surface of the exposed copper column; and removing oxide on the surface of the welding bump, and refluxing the welding bump. The columnar bump packaging process of the invention improves the electrical performance and the reliability of the welding bump and is applicable to chip-level packaging of the welding pad with a dense spacing 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

[0012] In the process of forming wafer-level chip size packaging in the prior art, since the solder bump material is in direct 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 welding 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

On the other hand, during the formation of solder bumps, the solder is easy to drip and affect the reliability of the product, especially for products with dense metal pads, the problem of short circuit between solder bumps is more likely to occur

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