Abstract

In some applications, such as that of detecting small particles on the surface of a silicon wafer, the state of the illumination very near the surface is important. The light here is a superimposition of that arriving from the illuminator and that reflected from the surface. In general, its polarization is different from that leaving the illuminator. In the case of grazing incidence illumination, the light undergoes a 180° phase shift on reflection. Since the s-polarized light has higher reflectivity than the p-polarized light, destructive interference in s light is more complete at the surface. Thus the light here is nearly p-polarized, and submicron particles at the surface experience the light of this polarization.

© 1987 Optical Society of America