Simultaneous Defect Inspection on the Surface and In the Interior of Bare Wafers Using a Simple Knife-edge Test

摘要

This paper proposes a new, simple, high-speed wafer-inspection method using a knife-edge approach. This method basically corresponds to a bright-field microscope except the light reflected from the wafer surface is partially cut by a knife-edge, which increases edge contrast in the cutting direction. In addition, the knife-edge test does not depend on the light wavelength and thus the light can have any wavelength as far as it is reflected by the wafer surface. Therefore, the knife-edge test, which uses visible light, can be employed simultaneously with a looking through inspection technique, which uses infra-red, with a single white-light source. The knife-edge method in tandem with a looking through inspection is implemented at a laboratory level and preliminary experimental results demonstrating edge enhancement are presented.