| abstract |
A bump structure for bonding leads to a semi-conductor, in which the bump has a thin lower portion (32) which overlaps and seals the edges of the passivation layer (18), and a thicker upper or stem portion (38) of smaller lateral dimensions to fit within the margins of the opening in the passivation layer. Thus, during bonding, downward compressive forces are applied primarily through the bump stem directly to the metal termination pad (14) beneath the bump, and very little force is applied to the edges of the passivation layer. This reduces the likelihood of passivation layer cracking, increasing device reliability. Because the bump stem is formed within the margins of the passivation layer opening, it has a flat top, resulting in better lead bonding. |