text: Electromigration decreases the reliability of integrated circuits (ICs). It can cause the eventual loss of connections or failure of a circuit. Since reliability is critically important for space travel, military purposes, anti-lock braking systems, medical equipment like Automated External Defibrillators and is even important for personal computers or home entertainment systems, the reliability of chips (ICs) is a major focus of research efforts.
  Due to difficulty of testing under real conditions, Black's equation is used to predict the life span of integrated circuits.
  To use Blacks equation, the component is put through high temperature operating life (HTOL) testing. The components expected life span under real conditions is extrapolated from data gathered during the testing.
  Although electromigration damage ultimately results in failure of the affected IC, the first symptoms are intermittent glitches, and are quite challenging to diagnose. As some interconnects fail before others, the circuit exhibits seemingly random errors, which may be indistinguishable from other failure mechanisms (such as electrostatic discharge damage). In a laboratory setting, electromigration failure is readily imaged with an electron microscope, as interconnect erosion leaves telltale visual markers on the metal layers of the IC.
  With increasing miniaturization, the probability of failure due to electromigration increases in VLSI and ULSI circuits because both the power density and the current density increase. Specifically, line widths will continue to decrease over time, as will wire cross-sectional areas. Currents are also reduced due to lower supply voltages and shrinking gate capacitances. However, as current reduction is constrained by increasing frequencies, the more marked decrease in cross-sectional areas (compared to current reduction) will give rise to increased current densities  in ICs going forward.
  In advanced semiconductor manufacturing processes, copper has replaced aluminium as the interconnect material of choice. Despite its greater fragility in the fabrication process, copper is preferred for its superior conductivity. It is also intrinsically less susceptible to electromigration. However, electromigration (EM) continues to be an ever-present challenge to device fabrication, and therefore the EM research for copper interconnects is ongoing (though a relatively new field).
  In modern consumer electronic devices, ICs rarely fail due to electromigration effects.  This is because proper semiconductor design practices incorporate the effects of electromigration into the ICs layout.  Nearly all IC design houses use automated EDA tools to check and correct electromigration problems at the transistor layout-level.  When operated within the manufacturers specified temperature and voltage range, a properly designed IC device is more likely to fail from other (environmental) causes, such as cumulative damage from gamma-ray bombardment.
  Nevertheless, there have been documented cases of product failures due to electromigration.  In the late 1980s, one line of Western Digitals desktop drives suffered widespread, predictable failure 12–18 months after field usage.  Using forensic analysis of the returned bad units, engineers identified improper design-rules in a third-party suppliers IC controller.  By replacing the bad component with that of a different supplier, WD was able to correct the flaw, but not before significant damage to the company's reputation.
  Electromigration can be a cause of degradation in some power semiconductor devices such as low voltage power MOSFETs, in which the lateral current through the source contact metallisation (often aluminium) can reach the critical current densities during overload conditions.  The degradation of the aluminium layer causes an increase in on-state resistance, and can eventually lead to complete failure.