Chip metal bump forming method

Abstract

The invention discloses a chip metal bump forming method, the method comprises the following steps of providing a silicon substrate, forming an electrode and a passivation layer on the upper surface of the silicon substrate, and exposing an electrode outwards from an opening of the passivation layer in the passivation layer; covering the upper surfaces of the passivation layer and the electrode with a seed layer; forming a photoresist layer on the upper surface of the seed layer; removing part of photoresist to form a photoresist opening which completely covers the area where the passivation layer opening is located; forming a metal column in the photoresist opening, wherein the metal column comprises a metal base layer and a metal tin layer which are sequentially formed from bottom to top; carrying out a chip probe test on the formed metal column; and forming a metal cap on the metal tin layer subjected to the chip probe test by adopting a reflux process. According to the method, thedamage to the end of the metal column in the chip probe testing process can be effectively repaired, needle marks formed in the chip probe testing process are rubbed down, therefore, the situation that the surfaces of the metal protruding blocks are uneven due to the needle marks is avoided, and then influences on the subsequent process and product performance are avoided.

Description

technical field [0001] The invention relates to the technical field of chip packaging, in particular to a chip metal bump forming method. Background technique [0002] In the process of semiconductor packaging, it is necessary to prepare bumps on the pad area of ​​the wafer first, then thin the crystal back to a certain thickness and cut it into individual chips, and finally connect the metal bumps on the chip to the solder pads on the substrate. pin binding. The fabrication and molding of metal bumps is a key technology in chip manufacturing and packaging. [0003] The fabrication of metal bumps generally ends with reflow soldering the tin pillars on top of the metal bumps to form a metal cap. In order to ensure a relatively stable yield rate of the bump manufacturing process and to save packaging costs, chip probe testing (CP, chip probing) is usually performed after the metal bumps are formed to screen the wafers and pick out unqualified chips. But when performing CP t...

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Problems solved by technology

But when doing CP testing, the probe needs to be in contact with the metal cap of the metal bump, which may cause damage to the metal cap to form test

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