Patent attributes
Methods for copper pillar protection may include forming a metal post over a contact on a semiconductor die, where the metal post comprises a sidewall. A metal cap may be formed on the metal post and may be wider than the width of the metal post. A solder bump may be formed on the metal cap, and a conformal passivation layer may be formed on at least the sidewall of the metal post. The metal cap may be rounded shaped or rectangular shaped in cross-section. The metal post and the metal cap may comprise copper. The metal cap may comprise a copper layer and a nickel layer. The seed metal layer may comprise one or more of titanium, tungsten, and copper. The conformal passivation layer may comprise a nonwettable polymer. Horizontal portions of the conformal passivation layer may be removed utilizing an anisotropic etch such as a plasma etch.
