Atomic layer deposition of Al2O3 thin films using trimethylaluminum and acetone

초록

(CH3)2CO (acetone) was used for the first time as an oxygen source for the metal oxide atomic layer deposition (ALD) process. The ALD of Al2O3 thin films on Si substrates was carried out using trimethylaluminum and acetone as the Al precursor and oxygen source, respectively. First-principles calculations of conceivable reactions were conducted to verify the validity of the ALD growth mechanism with the novel reactants. Al2O3 ALD with acetone showed ideal self-limiting saturation growth behavior with a deposition rate of 0.087 nm/cycle, which was slightly lower than that with water (0.097 nm/cycle). A 2–3-nm thick oxide layer was formed at the interface region after Al2O3 film deposition on the Si substrate for both oxygen source processes, and the interface layer change of approximately 30 nm thickness increase after annealing in air was comparable. In addition, the dielectric constants of the acetone- and water-based Al2O3 thin films were 7–8, with low leakage current density values (<10−7 A/cm2 at 0.8 V). Since the deposition amount per ALD cycle is always consistent and highly reproducible, the development of a new Al2O3 ALD process with a lower growth per cycle than conventional water-based ALD processes, enables a more precise control of the film thickness.

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