Spectral Reflectometry measures the light-scattering properties given a specific sample. The desired information is extracted by comparing the measurements with known scattering models, and searching for the "best fit".
Nova metrology solution use multi-channel reflectometry to reduce the ambiguity, increase the sensitivity to critical parameters, and improve measurement accuracy. The measurements are gathered using different wave lengths, polarizations and directions in order to deliver highly-accurate results.
The most notable benefit of multi-channel collection is reducing the ambiguity, and improving the sensitivity to critical sample parameters.
One measurement may be sensitive to a specific combination of sample properties, such as the cross-section area of a line , but not to the height , and line-width separately. This phenomenon is referred to as cross-talk between the two properties. Properly applied, multi-channel removes the cross-talk, enabling the identification of each distinct parameter.
Reducing the required prior knowledge
With multi-channel, the required prior knowledge is significantly reduced since extra sets of measurements are inherently provided. As a result setup time and recipe creation time are significantly reduced.