Aluminide intermetallics for advanced interconnect metallization: thin film studies

AlNi, Al3Sc, AlCu, and Al2Cu thin films have been investigated as potential alternatives for Cu in interconnect metallization schemes. Stoichiometric NiAl thin films of 56 nm thickness show a resistivity of 13.9 μΩ cm after post-deposition annealing at 600°C. Different capping layers were tested to overcome the formation of an oxide top layer. Al3Sc presents a resistivity of 12.5 μΩ cm after post-deposition annealing at 500°C (for 24 nm thick films). AlCu and Al2Cu outperform Ru films at 20 nm thickness and above (9.5 μΩ cm for 28 nm films). Challenges and integration feasibility are discussed.