The wafer bump production line uses wafer-level process technology, including thin film, photo, electroplating, etching and other advanced integrated circuit process technologies. Among them, the thin film process is to make pre-coating layer and barrier layer; the photo process is mainly for window opening before electroplating; the electroplating is for making of gold bumps and molding; the etching is mainly to get rid of redundant pre-coating layers and barrier layers. Therefore, the wafer bump production line can also be regarded as a small fab, using integrated circuit process technology and equipment.

▎Wafer bump process introduction:

• UBM (Under Bump Metallurgy) metal sputtering – pre-plating and barrier layers before wafer bumps are generated

• Photoresist coating – automatic photoresist coating using photoresist coating equipment

• Lithography – Photoresist exposure using a step-by-step lithography machine

• Development – Window opening development using wet developing equipment

• Plating – plating wafer bumps in the photoresist window opening area

• Photoresist removal – uses wet degluing equipment to remove photoresist from the chip surface

• UBM etching – removes excess pre-plating and barrier layers

• Metal toughening – use a toughener to change the lattice arrangement of the metal and adjust the hardness of the bumps

• AOI - automatic detection of chip production yield to ensure product quality