In Physical Design, what is Electromigration (EM), and which of the following is a primary method to mitigate it for a high-current net?
Electromigration is a reliability concern where the flow of electrons in a metal interconnect physically displaces metal ions, leading to voids (opens) or hillocks (shorts) over time. The effect is directly proportional to current density (Amps / cross-sectional area). For a high-current net like a power or ground rail, a standard mitigation technique is to increase the width of the metal wire. This increases the cross-sectional area, reduces the current density, and significantly improves the wire's lifetime against EM failure.
