Metrology of Periodic Structures
- In contrast, we evaluated full Mueller polarimetry in the most general conical diffraction configurations in the two ANR projects outlined below. Throughout both studies, the polarimetric responses of the grating structures were calculated by means of RCWA codes (both in 1D and 2D) developed by Tatiana Novikova and Martin Foldyna.
The “ScatteroMueller” Project
This study involved a set of gratings with CDs down to 50 nm nominal.
The fitted parameters (Middle critical dimension (CD), depth and sidewall angle (SWA)) exhibited very small variations with azimuth (in spite of very large variations of the raw spectra) and their values agreed very satisfactorily with the state of the art 3D AFM, taken as “gold standard”, as shown in figure below.
Similar results have been obtained for all gratings.
Contact : Nous contacter">Tatiana Novikova
The “MuellerFourier” Project
- Conoscopic Mueller polarimetry is particularly well suited to measurements in very small (a few μm wide) targets, and for overlay metrology.
- Conoscopic Mueller polarimetry needs only one target when other techniques, such as SCOL, require four to six 50 μm wide targets with controlled overlay offsets.
- The “ideal” machine would be one with the full conoscopic Mueller capability to generate and to detect arbitrary polarization states, for repeated measurements.
- Such a machine would accurately determine both the line profile and the overlay, which are currently measured by different systems.