On the Formation of an Anti-Reflection Layer on the Surface of Single-Crystal Silicon by Ion-Beam Etching

A technique is proposed for the formation of a developed regular structure on the surface of a polished single-crystal silicon wafer by ion-beam etching. It is shown that when single-crystal silicon is etched by a beam of accelerated Ar + ions with normal ion incidence on the sample surface, a surface region with a developed relief is formed, which can serve as a reflection-reducing layer. The reflection of radiation with wavelengths of 532, 633, 780, and 980 nm from a sample of single-crystal silicon with the orientation of the surface cut {100}, subjected to ion-beam treatment with Ar + ions with an energy of E ion = 400 eV for 10 hours (material removal was 7.5 µm) is studied. The specular-reflection curves of s -polarized radiation are obtained as functions of the angle of incidence. A decrease in the reflection coefficient relative to a polished silicon wafer is found at all investigated wavelengths. The largest decrease (more than 4 times) is recorded for a wavelength of 532 nm. It is shown that the range of heights of inhomogeneities formed during ion-beam etching increases linearly with an increase in the depth (time) of etching, which can be used to optimize the relief for a given wavelength.