Modeling of multi-species transfer during aluminum nitride vapor growth

AlN has attracted much attention in the past few years as a highly promising material for electronic and opto-electronic device applications. A halide vapor phase epitaxy (HVPE) system has been designed to grow high quality aluminum nitride layers at the growth rate up to 60 μm/h with the deposition temperature of 1000-1100°C and the pressure ranging of 5.5-760 Torr. A 3-D numerical model that is capable of describing multi-component fluid flow, surface chemistry, conjugate heat transfer, and species transport has been developed to help in design and optimization of the epitaxy growth system. The effects of reactor pressure on heat transfer and reactive mixing process are studied. The effects of carrier gas (N₂+H₂) and reacting gas (AlCl₃+NH₃) flow rates on species mixing process and deposition uniformity have also been investigated. To achieve a uniform reactive species distribution above the substrate under a high carrier and reacting gases flow rate, a baffle is added in between the adduct boat and the substrate. Different baffle sizes, shapes and locations are tested to examine the optional conditions for the best uniformity.