Area-Selective Low-Pressure Thermal Atomic Layer Deposition of Aluminum Nitride

This work demonstrates intrinsic area-selective depositionof AlNfilms by thermal atomic layer deposition (ALD). Using sequential pulsesof trimethylaluminum and NH3 at a substrate temperatureof 623 K, polycrystalline AlN was selectively formed on a thin layerof sputtered AlN that was patterned on thermal SiO2 grownon Si substrates. A pretreatment to remove native AlO (x) N (y) facilitated the selectivegrowth of ALD-AlN. Transmission electron microscopy, X-ray photoelectronspectroscopy, spectroscopic ellipsometry, and atomic force microscopyexamined the interfaces and layer thickness. As reported in this article,the deposition of AlN exhibits intrinsic selectivity, a trait thatcan be exploited to grow other III-nitrides selectively, such as GaN.