Accurate pre-alignment of wafers is key for each individual processing step. Contactless wafer edge measurement requires a dedicated optical head. Demcon has developed an optical head that is capable of detecting, statically and dynamically, the edge of a wafer with respect to the gripper and wafer marker. Sub-micron accuracy is achieved in all three dimensions with extended depth of focus and flat field. One of the key enablers of such performance is the use of custom optical and opto-mechanical designs for imaging and through lens illumination.

• Up to 6 mm out-of-focus, precision XY < 1 μm
• Up to 12 mm out-of-focus, precision XY < ~2 μm
• 24 mm field-of-view with TTL illumination