Ru:Al 2 O 3 Resistive Coatings Fabricated by Atomic Layer Deposition for Application in Microchannel Plates

This study investigated the atomic layer deposition (ALD) of ruthenium (Ru)-doped aluminum oxide (Al2O3) thin films for potential application as resistive layers in high-aspect-ratio microchannel plate (MCP) electron amplifiers. A Ru precursor, tricarbonyl(trimethylenemethane)ruthenium, C4H6Ru(CO)3 ([Ru(TMM)(CO)3]) and O2 coreactant were employed for Ru ALD, while trimethyl aluminum (TMA) and H2O were used for the Al2O3 ALD. A combination of in situ experimental measurements and theoretical calculations was utilized to investigate the adsorption behavior of the [Ru(TMM)(CO)3] precursor on hydroxylated surfaces and the growth characteristics of Ru ALD thin films. A relatively constant growth per cycle value of ∼1.7 Å/cycle was observed at 240 °C. By varying the ratio of Ru ALD cycles to Al2O3 ALD cycles, Ru:Al2O3 composite thin films were deposited where the resistivity could be tuned in the range of 107–1013 Ω.cm, which is suitable for application in MCPs. The impact of annealing on the composition and resistivity of the Ru:Al2O3 thin films was also explored. The results demonstrate the potential of Ru:Al2O3 films as resistive layers for MCPs and other applications including advanced microelectronics.