Fast measurement of the thickness and group refractive index distribution of solid plates by line-field dispersive interferometry

Real-time measurement of the thickness and group refractive index is crucial for semiconductor devices. In this paper, we proposed a fast synchronous method for measuring the thickness and group refractive index distribution of solid plates based on line-field dispersive interferometry. The proposed method measured the line-field distribution in an illuminated region through a single step. A low-cost spectrometer calibration method using an eight-channel dense wavelength division multiplexer was developed for verification. The line-field distribution of a three-step silicon wafer was successfully measured within 3.3 ms. The combined uncertainties for the geometrical thickness and group refractive index were <50 nm and 4 x 10(-4), respectively. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This paper proposes a fast synchronous method based on line-field dispersive interferometry for real-time measurement of the thickness and group refractive index distribution of solid plates. By measuring the line-field distribution in an illuminated region through a single step, the method successfully measures the line-field distribution of a three-step silicon wafer within a very short time.