Abstract
Conformal coating of boron-containing films via atomic layer deposition (ALD) could be used as a shallow dopant source for advanced 3D-transistor structures in VLSI manufacturing. Aiming this application, fluorine (F) -free precursors of boron such as boric acid (B(OH)3) and trimethyl borate (B(OCH3)3) were explored as ALD precursors in a combination with Al2O3 ALD process. The ALD of Al2O3 was performed using trimethyl aluminum (Al(CH3)3) and Deionized H2O. The complex chemistry resulted in deposition of boron containing composite films of (BxAl2-xO3). In-situ quartz crystal microbalance study was performed to evaluate the optimum ALD precursors dose times as well as confirms the self-limiting behavior of the ALD processes. Growth rate of composite BxAl2-xO3 processes under various ALD conditions are in the range of 0.8-1.1Å. The resultant boron containing BxAl2-xO3 films was analyzed for composition by x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), ellipsometry, and electrical capacitance measurements. Atomic composition of B was tailored by adjusting relative ratio of the B to Al precursors cycle during ALD process. A rapid thermal annealing was performed as a function of time and temperature and confirms B-diffusion in the Si(wafer) as well as changes in optical properties of the BxAl2-xO3 layers. Here we will present detailed investigation of ALD grown BxAl2-xO3 layers.