Apparatus and method for measuring surface potentials at a substrate

摘要

This research disclosure relates lo an apparatus and a method for measuring a potential at a substrate surface. Especially, it is related to an apparatus suitable for measuring surface potentials of a substrate without making direct physical contact with the surface. By means of surface scanning a two-dimensional potential map of the substrate surface can be obtained. Semiconductor manufactures often use substrates (wafers) provided with an insulating (backside) coating. Herewith, these substrates may carry electrical charges that cannot be removed easily. These charges may introduce a risk for the substrate and the product on the substrate, e.g., integrated circuits (IC's), as well as for the semiconductor equipment used during manufacturing and processing of the substrate. The accumulated charge may introduce a risk for, for example, a lithographic exposure apparatus or a metrology apparatus. It would be appreciated to gain more insight of the surface potentials of substrates during the manufacturing process. With this knowledge, preventive measures may be taken to avoid damages or failures.