Electromigration behavior of NiAl intermetallic compound as a next-generation interconnect material

This paper investigates the electromigration properties of NiAl, an intermetallic compound. NiAl samples with a stoichiometric composition of Ni<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">₀.</inf>₅Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">₀.₅</inf> were used, and the electromigration (EM) tests were conducted at a current density of 4 MA/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a temperature range of 250-300°C. After the EM tests, voids were seen on the cathode side, while hillocks were observed on the anode side. The drift velocity was determined from the void formation area at different temperatures, and the activation energy was calculated to be 1.41 eV, which is higher than the activation energy of Cu. Additionally, the anode side exhibited a Ni-rich composition, indicating the faster Ni drift velocity than Al. This is attributed to the electron localization in the Ni atoms.