Fitting-determined formulation of effective medium approximation for 3D trench structures in model-based infrared...

Area of Science:

• Materials Science
• Metrology
• Optical Engineering

Background:

• Model-based infrared reflectrometry (MBIR) is crucial for metrology.
• Accurate modeling of 3D trench structures for MBIR remains a challenge.
• Existing models struggle with the complexity of 3D geometries.

Purpose of the Study:

• To develop a simplified and accurate EMA formulation for 3D trench structures.
• To enhance the precision of MBIR metrology for complex geometries.
• To ensure the general applicability of the proposed model.

Main Methods:

• Developed a fitting-determined effective medium approximation (FD-EMA) formulation.
• Investigated the generality of FD-EMA across varying trench depths, pitches, and incidence angles.
• Validated the FD-EMA model using simulations on a taper trench structure.

Main Results:

• The proposed FD-EMA formulation provides a simplified model for 3D trench structures.
• FD-EMA demonstrated generality for various trench configurations.
• MBIR metrology using the FD-EMA model achieved a one-order higher accuracy compared to conventional EMA.

Conclusions:

• The FD-EMA formulation offers a significant advancement in modeling 3D trench structures for MBIR.
• This method enhances the accuracy and applicability of infrared metrology for complex 3D features.
• The findings pave the way for more precise metrology in microelectronics fabrication.