US Patent 7919834 Edge seal for thru-silicon-via technology

One or more multilayer back side metallurgy (BSM) stack structures are formed on thru-silicon-vias (TSV). The multiple layers of metal may include an adhesion layer of chromium on the semiconductor wafer back side, a conductive layer of copper, diffusion barrier layer of nickel and a layer of nobel metal, such as, gold. To prevent edge attack of copper after dicing, the layer of nickel is formed to seal the copper edge. To also prevent edge attack of the layer of nickel after dicing, the layer of gold is formed to seal both the layer of copper and the layer of nickel.