Full polarization optical profilometry

Abstract

Optical digital tomographic microscopy can be used for profilometry. The profile of the surface can be estimated from measurements of the complex diffracted far field obtained when the sample is illuminated successively under various incidences. Outside the validity domain of perturbative theories of diffraction, the profile is determined by using an iterative inverse wave scattering numerical method. In this paper we show that, for perfectly conducting surfaces, the two fundamental polarization cases involve different distances of interaction in the multiple scattering phenomenon. The use of both polarization cases in the inversion process leads to a considerable improvement of the lateral resolution. Robustness to noise is also discussed.

Nanometric Resolution with Far-Field Optical Profilometry

“…The origin of the super resolution obtained in TM polarization with the ODTM profilometer has been discussed in previous papers [11,12]. The long-range interactions produced by multiple scattering within the metallic surface lead to a strong coupling between the spatial frequencies of the field.…”

“…Details of the derivation of D for the perfectly conducting case are reported in Refs. [11,12,18]. In the present Letter, the derivation of D is extended to the case of surfaces having a finite relative permittivity ".…”

“…In this case numerical inversion algorithms based on a rigorous resolution of Maxwell's equations must be used. Recently preliminary numerical simulations have demonstrated [11,12] the potentialities of ODTM applied to profilometry.…”

“…As described in Ref. [12], to improve the resolution, we first apply the NK algorithm to the TE-polarized data using as the initial guess a plane. The final result is used as the initial estimate for the inversion of the TM-polarized data.…”

Inverse Wave Scattering of Rough Surfaces With Emitters and Receivers in the Transition Zone

“…This method was efficiently implemented in inverse scattering schemes for two-dimensional [6,16,17] and three-dimensional [18] scattering. However, one requisite of the method is that the incident field is a tapered wave, usually a gaussian beam.…”