Selective Atomic Layer Deposition of TiO2 on Silicon/Copper-patterned Substrates

Abstract

As microelectronic devices shrink, thinner diffusion barrier layers are needed to separate the copper and silicon substrates while leaving the copper vias open for conduction. Selective atomic layer deposition (ALD) of titanium dioxide(TiO2), a good barrier layer, onto silicon was studied by minimizing the exposure time to air of these substrates immediately before deposition. The minimized exposure time mimicked industrial conditions, where waiting before deposition is costly. Tetrakis(diethylamido)titanium (TDEAT) was used as the precursor, and water was the oxidizing agent. TDEAT was first deposited on silicon wafers using ALD to verify a steady, linear growth rate reported in the literature, and the measured rate of 0.9 ± 0.1 Å/cycle is consistent with values previously reported. Minimized exposure to air had no effect on the growth rate of TiO2 on silicon, and the effect on copper has yet to be determined.