title: Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry.
abstract: Optical scatterometry is the state of art optical inspection technique for quality control in lithographic process. As such, any boost in its performance carries very relevant potential in semiconductor industry. Recently we have shown that coherent Fourier scatterometry (CFS) can lead to a notably improved sensitivity in the reconstruction of the geometry of printed gratings. In this work, we report on implementation of a CFS instrument, which confirms the predicted performances. The system, although currently operating at a relatively low numerical aperture (NA = 0.4) and long wavelength (633 nm) allows already the reconstruction of the grating parameters with nanometer accuracy, which is comparable to that of AFM and SEM measurements on the same sample, used as reference measurements. Additionally, 1 nm accuracy in lateral positioning has been demonstrated, corresponding to 0.08% of the pitch of the grating used in the actual experiment.
authors.forename: Nitish
authors.initials: N
authors.lastname: Kumar
authors.forename: Peter
authors.initials: P
authors.lastname: Petrik
authors.forename: Gopika K P
authors.initials: GK
authors.lastname: Ramanandan
authors.forename: Omar
authors.initials: O
authors.lastname: El Gawhary
authors.forename: Sarathi
authors.initials: S
authors.lastname: Roy
authors.forename: Silvania F
authors.initials: SF
authors.lastname: Pereira
authors.forename: Wim M J
authors.initials: WM
authors.lastname: Coene
authors.forename: H Paul
authors.initials: HP
authors.lastname: Urbach