A Life-Test Study of Electromigration in Microwave Power Transistors

A life-test study was made of a microwave power transistor-employing aluminum metallization. The life tests were conducted under dc overstress conditions to accelerate the rate of failure as a result of electro-migration of the metallization system. Extrapolation of the data obtained showed a predicted MTF of approximately one hundred years for the device under test at a typical operating-current density of 8.4 × 104 A/cm2 and junction temperature of 150°C. Analysis of the failures revealed the presence of both aluminum and silicon electromigration, with the latter the primary cause of failure, A failure-rate model was constructed from the data relating MTF to activation energy, temperature, and current density.