HVPE of aluminum nitride, film evaluation and multiscale modeling of the growth process

The different steps of the fabrication of epitaxial AlN films (0.5-20 μm) by high temperature chemical vapor deposition called also HVPE (Hydride Vapor Phase Epitaxy) are reviewed (i) by thermodynamic modeling to analyze reactions in the chlorination chamber, (ii) by multicomponent heat and mass transport for a better knowledge of actual supersaturation of gas species above the substrate, (iii) by simple mechanical modeling to analyze the different source of stress during growth and (iv) by level set methods to represent the interface evolution at the micrometric level on patterned substrates. The evaluation of thin films is discussed in the light of modeling results. The joint use of the different modeling approaches allowed the quantification, for a 2″ substrate, of (i) the optimum temperature for the chlorination chamber (500 °C) to avoid AlCl specie formation, (ii) the transport of the main species AlCl₃ diluted in NH₃ and H₂ and (iii) the actual supersaturation at the growth interface on 2D surfaces or 3D patterned surfaces to promote lateral epitaxial overgrowth and improve crystalline quality. Finally, the upscaling from 2″ to 4″ substrates is computed and validated.