Dark-field semiconductor wafer inspection device

A set of two devices for inspecting semiconductor wafers, positioned facing each other in order to simultaneously inspect both faces of a wafer with different incident beam wavelengths, wherein each device comprises, in this order:

• a light source for emitting an incident beam towards a wafer along a first axis,
• a concentrator which is symmetrical relatively to a plane passing through the first axis and a second axis perpendicular to the first axis and provided with a mirror having an elliptical cross-section along a plane perpendicular to the second axis, and having a generatrix parallel to the first axis,
• first and second parallel slits being made laterally in first and second portions of the concentrator at the concentration points of the light scattered by the wafer and reflected by the second and first portions of the concentrator respectively, and
• one photomultiplier per split.