A Diffractive Element-Based Chromatic Confocal Thickness Measurement Device and Thickness Correction Method

Wafer thickness is a critical parameter in semiconductor manufacturing, influencing production costs, and chip performance. Traditional measurement methods using clamping devices often introduce errors due to uneven positioning or unstable clamping. This study enhances the dual-probe chromatic confocal system by incorporating a diffractive optical element that splits white light into three beams, with spectrometer wave peak counts detecting wafer tilt. A tilt correction algorithm was developed and tested. Experiments showed that with a 10 μm probe offset and 3° tilt, the measured thickness was 0.52 μm greater than in the parallel state. The algorithm significantly reduced tilt errors, improving thickness measurements by 50.2%. This advancement addresses limitations of traditional methods, offering a more precise and reliable approach for wafer thickness measurement, which is essential for optimizing semiconductor production processes.