Ellipso-Height-Topometry A new method for measuring surface topography, layer thickness, and for material recognition

The new concept of an Ellipso-Height Topometer provides the measurement of both the surface profile and locally distributed material areas which results in a laterally highly resolved material map which in turn contributes to a much more effective correction of measurement errors. All currently available optical profilometers produce artefacts at the boundaries of different materials. As an example an oil film on top of a metal surface will be measured with a non-linearly inverted profile amplitude and will therefore be seen as an indentation instead an elevated feature [3, 4]. The height of a conductor strip of a microelectronic structure will be measured equally wrong. Relatively large non-calibratable errors can occur when measuring layered structures. With this new Ellipso-Height Topometer these measurement errors and artefacts can be compensated by correcting for the phase jump of the reflected light of quasi-plane surfaces. To this end the local material distribution and their optical parameters will be calculated from the same data sets H (x, y) as used for the profile measurement and from these the material and layer resonance phases are calculated and the correction coefficients determined. This new optical method allows to measure correctly and with high spatial resolution structured surface profiles in the nm range and in addition provides more information about materials, layers and contaminated areas on the surface.