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

This work reports on the successful intrinsic area-selective deposition of GaN films by thermal atomic layer deposition at back-end-of-line compatible temperatures. Using sequential pulses of trimethylgallium and ammonia (NH₃) at a substrate temperature of 673 K, polycrystalline GaN is selectively formed onto AlN on substrates consisting of patterned AlN on thermal SiO₂. Before the deposition of GaN, a thin film of AlN is deposited selectively by atomic layer deposition on the patterned AlN to enable the deposition of GaN on AlN. The interfaces and layer thicknesses were examined by transmission electron microscopy, spectroscopic ellipsometry, and atomic force microscopy.