Atomic layer deposition of RuO2 using a new metalorganic precursor as a diffusion barrier for Ru interconnect

We report the ALD RuO
2
process using a new Ru metalorganic precursor, tricarbonyl (trimethylenemethane) ruthenium [Ru(TMM)(CO)
3
], and molecular oxygen (O
2
) as a reactant at the relatively low temperature of 180 °C for a diffusion barrier application of Ru interconnect. RuO
2
thin films could be prepared by controlling the reactant and precursor pulsing time ratio (t
o2
/t
Ru
) and the deposition pressure. The formation of RuO
2
phase is generally favorable at a higher pulsing time ratio (t
o2
/t
Ru
) and deposition pressure. It was also demonstrated that Ru single, the mixture phase of Ru and RuO
2
, and RuO
2
single phase could be controllably grown with deposition condition. The RuO
2
films deposited under optimized pulsing conditions showed resistivity of ~103 μΩ·cm, and a growth rate of ~0.056 nm/cycle with short incubation cycles of ~15 cycles. The diffusion barrier performance of ALD-RuO
2
thin films against Ru is analyzed using XRD and electrical impedance analysis. According to both analyses, the non-barrier layer structure [ALD-Ru (50 nm)/Si] began to lose its stability by forming ruthenium silcides at 750 °C, while the structure with a barrier layer [ALD-Ru/ALD-RuO
2
(5 nm)/Si] were stable up to 850 °C.