Failure analysis of bond pad metal peeling using FIB and AFM

Aluminum bond pads on semiconductor chips play an important role in chips f unctionality and reliability. Bond pad peeling during wire bonding process results in yield reduction. The failure mechanisms of the peeling must be i dentified so that potential reliability problem of poor bond pad adhesion c an be avoided. In this work, FIB, SEM, EDX, and AFM are used to identify th e root causes of the peeling. The possible root causes are found to be the presence of an extra layer of thickness of 0.14 mu m and the poly-silicon s urface roughness asperity due to prolonged BOE etching time.