Test Structure for Thick Metallization Electromigration

The test structure implements local quality by creating a tapered conductor piece where the width varies along its length. The narrow end is connected to the thick metal strip conductor while the wide end connects to the thin metal conductor. This gradual width transition creates a gradient in current density, concentrating the high current density at the narrow end where electromigration testing is needed, while the wide end maintains low current density to prevent premature failure. This resolves the contradiction by enabling high current density application locally at the test region without causing system-wide premature failure.

The invention applies parameter changes by modifying the geometric parameters of the conductor piece, specifically its width along the current flow direction. The conductor piece transitions from a narrow width at the thick metal connection to a wide width at the thin metal connection. This parameter change creates a current density gradient that enables high current density testing of thick metal conductors while maintaining low current density in the connecting conductor pieces, preventing their premature failure and enabling reliable testing of thick metallization systems.

The tapered conductor piece design implements local quality by creating distinct regions with different widths and current densities. The narrow region at the thick metal connection experiences high current density and serves as the electromigration test region, while the wide region at the thin metal connection experiences low current density and remains stable. This spatial differentiation of properties ensures that material migration occurs predictably at the intended test location rather than in the connecting conductor pieces, improving measurement precision while maintaining manufacturing simplicity.