Metal pad failure phenomena of biosensor due to spontaneous nickel silicide formation

Abstract

A FET (Field Effect Transistor) biosensor chip for an early diagnosis of disease was fabricated using semiconductor process. Metal pad failure phenomena were found after pad metal deposition process. The electrical I-V performance and cross-sectional TEM inspection were done to find out the root cause of this failure. The nickel silicide growth between Ni UBM (Under Bump Metal) and Si substrate was found. The root cause of this metal pad failure was proved to be the interfacial spontaneous nickel silicide reaction between Ni pad and top Si layers.