Coherence-length-constrained OPC for efficient mask segmentation in advanced lithography

Area of Science:

• Optical lithography
• Nanofabrication
• Image processing

Background:

• Coherence length defines optical correlation range, crucial for imaging systems.
• Current optical proximity correction (OPC) methods increase mask complexity and cost.
• Existing OPC over-segments edges, yielding no image quality improvement.

Purpose of the Study:

• To propose a novel OPC method based on coherence length.
• To reduce mask complexity and computational cost in advanced lithography.
• To maintain or improve imaging performance and exposure latitude.

Main Methods:

• Simulations analyzing mask variations' effect on aerial images and critical dimensions (CD).
• Development of a coherence-length-based OPC method.
• Restricting polygon edge segmentation to within the coherence length (max 3 segments).

Main Results:

• Mask variations significantly impact aerial image contours and CD within coherence length.
• The proposed method effectively mitigates image ripples for complex 2D patterns.
• Comparable critical dimension (CD) and exposure latitude (EL) performance achieved.

Conclusions:

• Coherence length provides a physical boundary for effective OPC.
• The proposed method enhances mask correction efficiency and simplifies fabrication.
• This approach offers practical guidance for advanced lithography mask optimization.