Apparatus for optical inspection of wafers during polishing

摘要

An optical system is disclosed for the inspection of wafers during polishing which also includes a measurement system for measuring the thickness of the wafers top layer. The optical system views the wafer through a window and includes a gripping system, which places the wafer in a predetermined viewing location while maintaining the patterned surface completely under water. The optical system also includes a pull-down unit for pulling the measurement system slightly below the horizontal prior to the measurement and returns the measuring system to the horizontal afterwards.