[15p-K304-1~11] 3.7 Optical measurement, instrumentation, and sensor

6:15 PM - 6:30 PM JST(9:15 AM - 9:30 AM UTC)

[15p-K304-9] High-sensitivity imaging of nanometer-scale surface variations using a centrally apertured wave

〇Keisuke Yoshiki^1,2, Norihisa Yoshimura² (1.Kochi Univ. of Tech., 2.CCS Inc.)

Keywords:

Polarization by Split Pupil Technology (PSPT),Nanostructural Surface Measurement,Machine Vision

When a λ/2 plate with a central aperture in the pupil plane is placed behind the objective lens, the ideal reflection from a flat surface does not change the incident polarization state, while a sample with a micro irregular surface such as a step, tilt, or contamination causes the paths through the λ/2 plate to intersect due to changes in reflection angle, generating orthogonal polarization. By selectively detecting this, height changes and surface inclination on the order of nm can be visualized with high contrast. This method can be used for microdefects for which conventional cameras tend to lack sensitivity, and is superior to differential interferometry in detecting inclination. In actual observation of polished wafer surfaces, waviness and scratches were clearly visualized and showed good agreement with simulations. This method is a powerful solution for detecting microstructures with high sensitivity in the machine vision field, where simple and fast observation is required.