Impact of surface structures on the inline vision inspection of antireflection coatings

At present inline measurements of antireflection coating (ARC) thickness are established, but there are still open questions concerning the influence of a varying surface texture quality on accuracy of ARC thickness measurement. Surface texture may be different due to process inhomogeneities. Thus, inline color inspection systems in production lines are often only used to detect inhomogeneities or spots in the ARC in order to sort the cells into different optical quality classes. This work aims at evaluating the possibilities and restrictions to determine the thickness of the ARC with inline vision irrespective of the wafer surface. Special emphasis has been put on textured monocrystalline wafers. Considering the reflection after texturisation the accuracy of ARC thickness measurement by color vision inspection may be improved significantly. Finally, it has been shown that an inline measurement of the reflection after texturisation would be possible with the same inline system and an aligned calibration