What is a seed layer?

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Seed layer is: (ADD thesis sentence)

Semiconductor-mounted devices have two main types of wiring layers: rewiring layers and build-up wiring layers. Photosensitive polyimide is used for the insulation layer of the rewiring, and a build-up wiring layer is a mixture of resin and silica filler for the insulation layer of the build-up wiring.

What these wiring layers have in common is the use of Cu (Copper) as the wiring material. Electroless plating has been used to form Cu wiring layers, but with the increasing need for high interlayer adhesion due to refinement and increase in the number of layers in recent high-density packaging products, it has become common to form seed layers on insulating materials by sputtering and Cu wiring by electroplating.

In addition to the chamber that forms the Cu seed layer, the sputtering equipment for semiconductor mounting devices is equipped with a Degas chamber that removes moisture from the insulating layer, a dry etching chamber that cleans the surface of the substrate before film formation, and an alloy-forming chamber (Ti or Cu) that enhances the adhesion strength between the resin and the seed layer. ULVAC’s sputtering equipment is built to achieve high adhesion and coverage for photosensitive polyimides and build-up wiring layers.

WLP (Wafer-Level Packaging) manufacturing process

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