Fast micromirror selection and angle setting algorithm for freeform pupil in the illumination system for immersion...

Area of Science:

• Optical Engineering
• Semiconductor Manufacturing

Background:

• Stringent performance requirements for illumination pupils in immersion lithography machines are driven by improving lithography resolution.
• Energy balance and polarization properties are critical for advanced lithography, especially for technology nodes below 40nm.
• Micromirror arrays (MMA) are used to adjust angular distribution for pupil characteristics.

Purpose of the Study:

• To propose a micro-mirror selection and angle setting algorithm for maintaining freeform pupil characteristics.
• To ensure energy balance in both unpolarized and polarized states for immersion lithography.
• To enhance computational speed for engineering applications.

Main Methods:

• Developed a micro-mirror selection and angle setting algorithm.
• Utilized freeform pupil illumination optical models for simulations.
• Validated algorithm accuracy for unpolarized and polarized light states.

Main Results:

• Achieved significant improvement in energy balance, reducing it to 0.08% in both unpolarized and polarized states.
• Demonstrated the algorithm's effectiveness in maintaining key characteristics of the freeform pupil.
• Enhanced computational speed, reducing calculation time from 600s to 0.1s.

Conclusions:

• The proposed algorithm effectively ensures energy balance and maintains freeform pupil characteristics in immersion lithography.
• The algorithm's computational efficiency makes it suitable for engineering applications.
• This work contributes to advancements in high-resolution semiconductor lithography.