Positioning the wafer stage using capacitive sensors

Capacitive displacement sensors are used for fine positioning tasks in the wafer stage. These sensors measure the position of the stage at various points, which is particularly useful for fine alignment. Thanks to their triaxial design, the sensors are insensitive to electromagnetic fields and achieve a resolution in the nanometre range. Furthermore, the sensors offers extremely high long-term stability. The non-contact sensors are designed for the vacuum range and can also be used in the UHV range.