Patent ID: 8237458

Claim:
An electromigration testing method for a device under test with an interconnect structure, comprising the steps: subjecting, for a first stress time span, the interconnect structure to a first stress condition, which comprises a first electrical current density in the interconnect structure and a first temperature of the interconnect structure, so as to force occurrence of a step resistance-increase of the interconnect structure due to electromigration in a first layer of the interconnect structure; and subjecting the interconnect structure to at least three respective predetermined stress conditions, which differ from each other in their value of the electrical current density in the interconnect structure or of the temperature of the interconnect structure, for at least three respective stress time spans after the occurrence of the step resistance-increase, and concurrently measuring a test quantity indicative of an electrical resistance of the interconnect structure, wherein the first temperature value of the first stress condition is higher than any of the temperature values used in the stress conditions after occurrence of the step-resistance increase, and the first current density value of the first stress condition is higher than any of the current density values used in the stress conditions after occurrence of the step-resistance increase.