Substrate-Dependent Area-Selective Atomic Layer Deposition of Noble Metals from Metal β-Diketonate Precursors

Area-selective ALD of Ir, Ru, and Rh with excellent substrate selectivity was achieved by using metal β-diketonates, i.e., Ir(acac)3, Ru(thd)3, and Rh(acac)3, as precursors with either O2 or air as a coreactant. Native SiO2 and Ru were identified as growth surfaces while low-k SiOC, native oxide terminated Cu and Co, Al2O3, ZrO2, and HfO2 were identified as the nongrowth surfaces. UV (254 nm) irradiation in air was proven efficient to activate the low-k SiOC surface for the noble metal growth. UV exposure of 1 min was sufficient for the growth activation yet without causing any damage to the low-k material. Selective growth of the noble metals was successfully demonstrated on a UV-irradiated test chip that has micro- and nanometer-scale low-k SiOC/Cu patterns. At the optimal selective deposition temperatures, that is 225 °C for the Ir, 300 °C for the Ru, and 250 °C for the Rh, films with a thickness of at least 10 nm for Ir and ∼30 nm for Ru and Rh can be selectively deposited on the UV-activated low-k SiOC regions, while no growth occurs on Cu regions, as characterized by SEM, TEM, and EDS.