26 August 2005 Influence of the real-life structures in optical metrology using spectroscopic scatterometry analysis
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During the last five years scatterometry measurement using ellispometry and reflectometry has met a great interest in nano and microelectronics fab. Today, this technology of measurement is used to control lot production and has become mature for 1D-grating measurements. Nevertheless, some aspects of this method of measurement are always under research studies. This paper focuses on one of these aspects: the evaluation of the influence of the "real-life 1D-structure" (linewidth variations along the lines and line to line, roughness, defect inside the grating) on spectroscopic signatures and on scatterometry measurement methods. The measurements have been carried out on KLA-TENCOR ellispometer and on Nanometrics reflectometer in order to compare the two methods of measurement. The simulations have been done with MMFE (Modal Method of Fourier Expansion) software developed by LETI labs. To control defect characteristics and defect distributions, one wafer was printed using electron beam lithography. The aim is the evaluation of the impact of defects in the grating on the spectroscopic signatures and its influence on extracted geometrical parameters by fitting the experimental curves. Different deviations to real-life structures have been studied. First we focus on the influence of typical defects of lithography processes such as bridging and partial destruction of lines and on the influence of CD distribution values inside the grating. Then, we study the influence and the possibilities of measuring Line Edge Roughness (LER). For LER measurements different targets have been also exposed on e-beam tool. Simulations and experimental measurements have been carried out. All the results obtained have been compared with imaging standard tool: top down SEM measurement.
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R. Quintanilha, R. Quintanilha, J. Hazart, J. Hazart, P. Thony, P. Thony, D. Henry, D. Henry, } "Influence of the real-life structures in optical metrology using spectroscopic scatterometry analysis", Proc. SPIE 5858, Nano- and Micro-Metrology, 58580C (26 August 2005); doi: 10.1117/12.612081; https://doi.org/10.1117/12.612081

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