UNCERTAINTY IMPROVEMENT OF GEOMETRICAL THICKNESS MEASUREMENT OF A SILICON WAFER USING A FEMTOSECOND PULSE LASER

摘要

We describe a method to simultaneously measure geometrical thickness and refractive index of a silicon wafer using a femtosecond pulse laser having 100 nm spectral bandwidth. The improved phase measurement algorithm is applied to increase insensitivity to environmental disturbances and interferometer noise. The measurement results show that the geometrical thickness and refractive index of a silicon wafer were measured to be 320.699 μm and 3.621 respectively, which are the improved results by about one order of magnitude in comparison with previous research. By considering the dispersion effect caused by 100 nm bandwidth source, the conclusion can be reached that there is no dispersion effect on measurement of geometrical thickness.