Date of Award
Charles H. Winter
Atomic layer deposition (ALD) affords highly conformal thin films with precise thickness control due to its self-limited growth mechanism. ALD enables the increasing demands for smaller feature sizes in microelectronics devices to be met. Area-selective ALD growth is receiving attention in the fabrication of microelectronic devices, since it can eliminate complicated etching steps from the fabrication process and minimizes expensive and toxic reagent use. Selectivity can be achieved by tailoring the surface chemistry of the precursor and substrate. To date, few area-selective ALD processes have been reported for metallic films. Thin films of cobalt metal deposited selectively are of considerable interest for use in microelectronics devices, specifically as a metallization liner in sub-10 nm logic nodes. Our laboratory has recently reported an ALD process for cobalt metal thin films using bis(1,4-di-tert-butyl-1,3-diazabutadienyl)cobalt(II), Co(tBu2DAD)2, and formic acid. This process affords high-purity, low-resistivity cobalt films. Excellent cobalt metal film growth also occurs on metallic substrates, with a growth rate of ~0.95 Å/cycle. In this work, I will describe the early stage nucleation and selective growth of cobalt metal from Co(tBu2DAD)2 and formic acid on ruthenium, platinum, and copper substrates. No cobalt metal growth is observed on nonmetallic substrates. I will also describe the development of a new inherently substrate-selective ALD process for high-purity, low-resistivity (~13 µΩcm) cobalt metal from Co(tBu2DAD)2 and alkyl amines, with a GR of 0.98 Å/cycle on metal substrates. No cobalt metal growth is observed on dielectric substrates. I will also describe the development of a new inherently substrate-selective ALD process for high-purity, low-resistivity (~20 µΩcm) nickel metal from Ni(tBu2DAD)2 and alkyl amines, with a growth rate of 0.60 Å/cycle on metal substrates. No nickel metal growth is observed on dielectric substrates.
Kerrigan, Marissa Marie, "Selective Atomic Layer Deposition Of Transition Metal Thin Films" (2017). Wayne State University Dissertations. 1822.