Epi-film thickness measurements using emission Fourier transform infrared spectroscopy. II. Real-time in situ process monitoring and control

Real-time in situ applications of the emission Fourier transform infrared (E/FT-IR) technique are reported in this paper. For real-time process monitoring, we found that the real-time growth rate measured by the E/FT-IR is responsive to variations of process parameter(s) (i.e., temperature, pressure, and gas composition). For real-time epi-film thickness control, two control algorithms were used: 1) first past the post (FPP) method; and 2) linear forecasting. A closed-loop precise epi-film thickness end-point control is demonstrated. Additionally, by real-time monitoring of the incubation time and growth rate, we are able to obtain qualitative information about the effectiveness of the predeposition wafer cleaning process. Thus, plasma cleaning process optimization time is shortened and postdeposition materials characterization cost is reduced. Using the optimized conditions, we have demonstrated the growth of defect free epitaxial silicon films