Gas-Phase Mixing and Dispersion in a Diffusion Furnace

Gas-phase mixing and dispersion in a typical commercial-scale diffusion furnace was investigated using computational fluid dynamic simulations and experimentation. Five regions were defined within the furnace: (i) entrance volume, (ii) annular volume around the wafer-source stack, (iii) radial volumes between wafer-source pairs, (iv) intermediate volumes between successive wafer carriers, and (v) exit volume. The mixing characteristics within each of these volumes was quantified and appropriate mixing models were defined based on the relative amount of backmixing or gas exchange within and between these volumes. A dispersion-based approach was then used to develop a simplified model describing the transient transport of water vapor (H 2 O) during a typical hydrogen injection cycle. Model parameters were calibrated using experimental data from tracer impulse studies.