Dark field imaging of high aspect ratio structures - a simple model

Area of Science:

• Optics and Photonics
• Computational Modeling
• Nanotechnology

Background:

• Simulating optical imaging of complex micro- and nano-structures is computationally intensive.
• Existing models struggle with in-plane scattering in high aspect ratio geometries.

Purpose of the Study:

• To develop a simplified, faster model for dark-field optical imaging simulations.
• To accurately simulate scattering effects in three-dimensional micro- and nano-structures.

Main Methods:

• Utilizes incremental theory of diffraction to model primary scattering from edge waves.
• Incorporates secondary scattering by re-scattering from nearby features.
• Simplifies diffraction coefficients and limits illuminating beams to those entering the objective lens.

Main Results:

• The simplified model reduces simulation time for object fields.
• Comparison of transverse electric (TE) and transverse magnetic (TM) polarization images.
• Benchmarking results against a vectorial finite element model confirms accuracy.

Conclusions:

• The proposed model offers an efficient approach for simulating dark-field optical imaging.
• Applicable to optical inspection of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) with vertical features.