Generation of trapezoidal illumination for the step-and-scan lithographic system

Area of Science:

• Optical lithography
• Semiconductor manufacturing
• Advanced illumination techniques

Background:

• Achieving uniform dose exposure is critical in optical lithography for semiconductor fabrication.
• Step-and-scan lithography systems require uniform and trapezoidal illumination in the scanning direction on the wafer.
• Conventional methods for achieving trapezoidal illumination can be complex and energy-inefficient.

Purpose of the Study:

• To propose a novel design strategy for generating trapezoidal illumination in optical lithography.
• To achieve both high uniformity illumination and fixed integral energy for trapezoidal illumination patterns.
• To simplify the assembly process and improve energy utilization compared to existing methods.

Main Methods:

• A light uniform device incorporating a microlens array, microcylindrical array, and Fourier lens was designed.
• This device directly produces trapezoidal illumination at the scanning slit.
• The strategy focuses on direct generation without energy blocking.

Main Results:

• The proposed method successfully produces uniform trapezoidal illumination.
• Simulation results confirm the maintenance of illumination uniformity.
• Improved energy utilization and lithography system throughput were demonstrated.

Conclusions:

• The new design strategy offers a simpler and more direct approach to trapezoidal illumination.
• The method enhances energy efficiency and throughput in step-and-scan lithography.
• This technique provides a practical solution for uniform dose exposure in advanced lithography.