Cratering - EESemi.com Gallery

Cratering

Figure 1. Cratering - Silicon Damage Under the Bond Pad

Figure 1 shows a SEM photo of cratering, or the failure mechanism wherein the silicon under the bond pad has been mechanically damaged. Gross cases of cratering results in a chunk of the underlying silicon being chipped off and dislodged from its place, forming a 'hole' or 'crater' on the silicon substrate (hence the term 'cratering').

Cratering can be due to several causes, but the most common reason for cratering is over-bonding, or the situation wherein the bonding tool has transmitted excessive stresses to the bond pad during wirebonding. Cratering can result in lifted bonds, so an engineer analyzing a bond lifting issue must look at the bond pad closely during investigation to ensure that the appropriate corrective action will be taken.