Arbitrary trapezoidal illumination generation method based on variable slits for optical lithography

Area of Science:

• Optical Engineering
• Lithography Technology

Background:

• Trapezoidal illumination enhances light intensity uniformity in step-and-scan lithography.
• Variations in laser pulses and coherence factors alter optimal trapezoidal shapes, impacting uniformity.

Purpose of the Study:

• To introduce a novel method for generating arbitrary trapezoidal illuminations using variable slits.
• To mitigate the effects of changing laser pulses and coherence factors on illumination uniformity.

Main Methods:

• Development of a variable slit system for precise trapezoidal illumination control.
• Optical simulations to verify performance across different coherence factors and illumination modes.

Main Results:

• The proposed variable slit method successfully generates arbitrary trapezoidal illuminations.
• Optimized illumination outlines were achieved by balancing pulse quantization error and energy loss.
• The method maintains trapezoidal outline consistency by adjusting blade positions for different coherence factors.

Conclusions:

• The variable slit method offers superior control over trapezoidal illumination compared to traditional techniques.
• This approach enhances integrated uniformity of light intensity in advanced lithographic systems.
• The system demonstrates adaptability and robustness under varying operational parameters.