Abstract
When a collimated beam of light is reflected by an approximately flat, mirror polished object and a screen is placed in the reflected beam some distance away from the object, a ‘‘magic mirror image’’ or Makyoh topogram of the object is formed on the screen. For objects with surface height variations, the topogram will not have a uniform intensity distribution, but even small height variations will show up strongly amplified as dark or bright patches/lines. Makyoh topography has been used for a number of years as a sensitive tool for the inspection of mirror polished surfaces, and in particular, semiconductor wafer surfaces. The main drawbacks of conventional Makyoh topography are, first, the ambiguity of interpretation because almost identical Makyoh topograms can result from an object with some given surface height profile and constant reflectivity, an object with constant surface height and a given nonuniform reflectivity profile, or an object with both height variations and a nonuniform reflectivity profile. The second drawback is the lack of quantitative interpretation, for example, surface height values cannot be obtained from the contrast in conventional topograms. I address these problems and describe a technique that for the first time enables the quantitative and unambiguous interpretation of Makyoh topograms.
