Scratch detection method and apparatus

摘要

A method of identifying discontinuities in the surface of a substrate is herein disclosed. An object plane of an imaging system is positioned at a focal position associated with a discontinuity and an image is captured, the discontinuity having a relatively higher contrast with respect to the remainder of the surface of the substrate. The discontinuity is thereby more readily discernable than when the focal plane is positioned at the surface of the substrate. Analysis of discontinuities may include the extraction of discontinuity characteristics.

主权项

1. A method of inspecting a surface of a semiconductor substrate, comprising:
identifying a potential discontinuity of interest that may appear at the surface of the substrate; determining a range of focal distances above the surface of the substrate and above the potential discontinuity of interest where light reflected from the potential discontinuity of interest is likely to be focused, the determined range of focal distances being at least partially different than a nominal focal distance of a system used for inspecting the surface of the semiconductor substrate at which the surface of the semiconductor substrate is substantially in focus; positioning a focal plane of an imaging system with the range of focal distances; capturing an image of the substrate; determining the presence of a discontinuity of interest on the substrate, if any, based on a level of contrast in the captured image between the discontinuity of interest and a background of the image; and characterizing the discontinuity of interest on the substrate, if any, by correlating a focal distance of the discontinuity of interest with a discontinuity characteristic including determining a depth and at least one of a width, a geometry, and a topography of the discontinuity based on the focal distance.