MODELING AND SCALE-UP OF MULTIWAFER LPCVD REACTORS

The deposition of thin films in a hot- wall multiwafer low-pressure chemical vapor deposition (LPCVD) reactor is an important unit operation in the manufacture of modern integrated circuits. In this article, our previously published model for the multiwafer LPCVD reactor has been combined with in-situ temperature measurements to accurately predict the axial and radial film thickness distributions for a polysilicon deposition process. The model describes in detail multicomponent mass transport, the reactor's thermal environment based on in-situ temperature measurements, and the reactor geometry including inlet and outlet sections as well as downstream injectors. Model predictions were compared with experimental data from two industrial-scale polysilicon reactors at SEMATECH and from a smaller research reactor. Approximate scale-up rules for the important special case of larger wafers were derived from the model equations and tested by simulation. The rules compare well with the results from a nonlinear program in which the axial variation of film growth rate was minimized.