| abstract |
A method of protecting a copper pillar can include forming a metal pillar on a contact on a semiconductor die, wherein the metal pillar includes a sidewall. The metal cover may be formed on the metal post and may be wider than the width of the metal post. Solder bumps may be formed on the metal cap, and a conformal passivation layer may be formed on at least sidewalls of the metal posts. The cross section of the metal cover can be molded into a rounded or rectangular shape. The metal post and metal cover can include copper. The metal cover may include a copper layer and a nickel layer. The seed metal layer may include one or more of titanium, tungsten, and copper. The conformal passivation layer can comprise a non-wettable polymer. The horizontal portion of the conformal passivation layer can be removed using an anisotropic etch (eg, plasma etch). |