In advanced transistor fabrication, many process steps have the potential to alter or degrade carrier mobility, resulting in device timing variability and loss of manufacturing yield. For example, each implant-anneal stage produces an intermediate mobility which is critical to final device performance. Moreover, uniformity at each stage is essential to maximize manufacturing yield. Thus the ability to rapidly and non-destructively measure carrier mobility on product wafers is key to yield. However, current mobility measurement techniques are destructive or require contact with the sample, risking damage and/or contamination, and can lead to misleading results.
With the Z-scan photo-modulated reflectance technology developed by Xitronix, you can now make precise, non-contact mobility measurements directly on product wafers. The Xitronix technique is based on profiling the PMR signal as the sample is stepped through focus. A simple nonlinear least squares fit provides diffusion lengths and recombination lifetimes. The carrier mobility or any other carrier transport property is then known. Also, statistical estimates of fit error from the least squares analysis establish the measurement precision. This provides a quick, accurate, and precise optical mobility measurement with micrometer scale resolution.
2018 Journal of Applied Physics
2018 Optical Mobility Letter
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US Patent 8,300,227
US Patent 7,391,507