Scaling up a horizontal HVPE reactor

Abstract

We have constructed a hydride vapor phase epitaxy (HVPE) reactor capable of producing four inch Gallium Nitride wafers. The design is based on a previously built and successfully operated two inch wafer system [Dam C.E.C., Grzegorczyk A.P., Hageman P.R., Dorsman R., Kleijn C.R., Larsen P.K., The effect of HVPE reactor geometry on GaN growth rate—experiments versus simulations , J. Cryst. Growth 271 (2004) 192; Dam C.E.C., Hageman P.R., Larsen P.K., Carrier gas and position effects on GaN growth in a horizontal HVPE reactor: an experimental and numerical study, J. Cryst. Growth 285 (2005) 31; Dam C.E.C., Grzegorczyk A.P., Hageman P.R., Larsen P.K., Method for HVPE growth of thick crack-free GaN layers, J. Cryst. Growth 290 (2006) 473 [1−3]], essentially by geometrically scaling up all dimensions by a factor λ = 2. To obtain identical processes in both reactors, we applied a scaling analysis based on the dimensionless numbers describing the processes in the system, i.e. the Reynolds, Grashof, and surface Damköhler numbers. When scaling up the reactor dimensions by a factor λ, these dimensionless numbers can be kept constant by adjusting the pressure and the inlet velocities of the gasses as p ∝ λ − 3 / 2 and ν∝ λ 1 / 2 respectively, and the inlet mole fraction of the rate limiting precursor GaCl as f in∝ λ. With the applied scaling rules, identical flow and deposition profiles are obtained in the scaled-up reactor. To verify our scale-up theory, we simulated both systems using computational fluid dynamics (CFD). The calculated flow path lines, concentration and depositions contours of the smaller and larger systems, when correctly scaled, agree very well with each other.