In-line measurement characterization for multi-layers film stack of SiGe by advance spectroscopy ellipsometer

Faster time to results is becoming more and more critical for chip makers to build up the production monitoring capability on advanced process development. Especially for SiGe's process, which uses SEG process by adding germanium. SiGe products provide higher frequency and lower power dissipation than traditional Si based products due to lower energy band-gap. SiGe process can be integrated to current semiconductor process easily with lower cost comparing to GaAs process. The combination of HBT and CMOS is excellent on wireless and optical fiber communication application. This application introduce a SiGe's in-line measurement method by using spectroscopy ellipsometer, which offers a non-destructive and ultra fast measurements than typical metrology tools, such like RBS, XRD or SIMS, on both box profile and gradient profile of varied Ge concentration of the films. By characterizing the different RI interval of the dispersion curves of SiGe-films, single or multi layers, through spectroscopy ellipsometer, we may estimate the film thickness and the peak concentration of germanium. A correlation of this in-line method with off-line method, such as XRD or SIMS, is provided through different RI-intervals of SiGe films as a comparison. The content of this paper offered experimental measurements data, which is not only on monitor wafers but also on production wafers including different box and gradient profiles of Ge concentration of the SiGe films via spectroscopy ellipsometer.The optical method is highly reducing the fabrication costs and accelerating production yields.