Efficient representation of mask transmittance functions for vectorial lithography simulations

Area of Science:

• Optics
• Computational Physics

Background:

• Accurate modeling of thick mask transmittance functions is crucial for optical simulations.
• Incident-angle dependence complicates mask transmittance modeling.

Purpose of the Study:

• To propose a generalized and efficient method for representing the incident-angle-dependent mask transmittance function (MTF) of thick masks.
• To enable faster and more accurate optical simulations involving thick masks.

Main Methods:

• The proposed method expands the MTF into a series using predetermined basis functions and expansion coefficients.
• Basis functions are computed offline, while angle-dependent coefficients are calculated online.
• The method was validated using near-field and optical image simulations.

Main Results:

• The generalized method accurately represents the incident-angle-dependent MTF of thick masks.
• The approach demonstrates superior speed performance compared to existing methods.
• Simulations confirmed the excellent accuracy of the proposed representation.

Conclusions:

• The series expansion method provides an efficient and accurate way to model thick mask MTFs.
• This technique significantly improves the computational speed of optical simulations.
• The proposed method is a valuable tool for advanced optical design and analysis.