Generalized Ellipsometry Measurement based on Variable Angle Driven by Single Motor

Abstract

Abstract: With the development of microelectronics, semiconductors, and nanotechnology, thin-film materials have been widely used in electronic and optical components, and the thin-film thickness is an essential indicator of the performance and reliability of components. For quick, non-destructive, and accurate thickness measurements, generalized ellipsometers have attracted a considerable attention of researchers. On account to the available commercial ellipsometers are usually need two motors to realize the variable angle (one used to control the polarization state generator/analyzer and the other to the sample stage), which is faced with problems such as complex structure, high cost and difficulty in optical path calibration after angle change. Therefore, a new variable angle structure driven by single motor is proposed in paper, in which the polarization state generator is fixed and the polarization state analyzer  and the sample stage are driven simultaneously using single motor to realize the variable angle. The standard thin-film samples of Au, Ag, and Cu with a thickness of 50 nm were tested by the constructed generalized ellipsometry system. The results showed that the thicknesses of the three samples were all in the range of 50±2 nm, and when the incident angle was 70°, the system measurement error was minimized. The results show that the proposed ellipsometry system with variable angle driven by single motor having the advantages of higher integration,simple operation, and low cost.