Evaluating the Effects of Modeling Errors for Isolated Finite 3D Targets

Area of Science:

• Metrology
• Nanotechnology
• Optical Science

Background:

• Optical 3D nanostructure metrology uses model-based approaches for sub-wavelength critical dimension (CD) determination.
• Accurate measurement of nanoscale features is crucial for advanced manufacturing and research.

Purpose of the Study:

• To evaluate methods for obtaining key CD and shape parameters from in-die metrology targets.
• To investigate the impact of model simplifications on measurement accuracy.

Main Methods:

• Utilizing a model-based metrology approach with physical models and simulations.
• Comparing simulation outputs with actual measurement data to refine model input parameters.
• Analyzing systematic errors introduced by simplifying 3D nanostructures to 2D models.

Main Results:

• Identified systematic errors in 2D modeling of 3D nanostructures, particularly for shorter features.
• Demonstrated how these errors can influence model fitting to measurement data.
• Simulation results highlight the necessity of considering 3D effects.

Conclusions:

• The simplification of 3D nanostructures to 2D models introduces systematic errors in optical metrology.
• Specific experimental setups, including illumination numerical apertures and focal ranges, can enhance the validity of 2D approximations.
• Balancing model accuracy and computational efficiency remains a key challenge in nanostructure metrology.