In-line FTIR for epitaxial silicon film thickness measurement on an Applied Materials Centura cluster tool

A technique for integrating a Fourier transform infrared (FTIR) spectrometer into an Applied Materials (AMAT) 5200 Centura single-wafer multi-chamber cluster tool has been developed. The FTIR spectrometer was optically interfaced to the cool-down chamber of the reactor using a set of modular transfer optics and a modified cover on the cool-down chamber. The instrument provided post-process in-line measurement of epitaxial silicon film thickness. Data acquisition and analysis required for the thickness measurement, was performed within seconds. The effect of wafer temperature on FTIR thickness measurement was observed and characterized. Repeatability and reproducibility tests revealed the measurement capability of this in-line FT-IR metrology was comparable to commercially available off-line FTIRs. The addition of the in-line FT-IR system does not adversely affect machine throughput.