What is the defect called in which the force or ultrasound of wire bonding cracks the insulator or silicon beneath the bond pad?

Answer: B. Cratering (cracking under the pad)

If the bonding load or ultrasonic energy is too high, or the wire is hard, the layers under the pad can crack like a crater. Particular care is needed with hard copper wire and with pads on weak low-k films.

• A. Punch-through is the merging of a transistor's source and drain depletion layers.
• B. Correct. It is cracking beneath the pad.
• C. Dishing is the recessing of a line's center during CMP.