Comparability study of different methods of measurement in the case of holographic grating

摘要

Evaluation of Micro geometrical surface such as holographic grating tends to depend on the method of measurement. Comparability of different methods, mainly SEM and AFM has been Investigated. It is considered that holographic grating has good surface characteristic as specimen because they have dominant profiles. One specimen has grating interval of about 2 μm, others has that of about 5μm. The surface roughness of two kinds of specimens by two methods has been evaluated, and compared. 3D topographic data have been collected in both methods, and analyzed by the same PC based software. After all, height values by SEM tend to be smaller than these by AFM. And, Space values such as peak intervals, have good coincidence. However, estimation of valley angle of grating indicated a little bit larger than expected by both methods. The reason of these results has been Investigated by tilting specimen. Because, it is expected that steep sided profile of grating surface has influence on measured profile. Steep slope have some bad Influence on both methods, and especially on the SEM measurement due to electro-charging on ridges. It is found that comparability is suffered from such phenomena.