While aluminum offers many advantages in semiconductor manufacturing, it faces a number of challenges as chip process sizes continue to shrink:
Increased resistance: As the width of the metal wire decreases, aluminum becomes more resistive, resulting in lower signal transmission speeds, especially in high frequency circuits, where aluminum may not be able to perform as well as needed.
Electromigration effects: Aluminum is susceptible to electromigration, which is the migration of metal atoms in response to an electric current, under high current density conditions, leading to wire breakage or short circuits.
Substitution of low-k materials with copper: To address these challenges, many modern integrated circuits use copper as a metal interconnect material because copper has lower resistivity and better electromigration properties than aluminum. In addition, low-k dielectric materials are widely used to reduce capacitive effects and improve signaling speed.
Nonetheless, aluminum is still widely used in many mature processes, especially in some low-power, low-frequency or more mature process nodes, where it is still an ideal choice.