Analysis of Dynamic Stability Control of Light Source in Immersion DUV Lithography

Area of Science:

• Semiconductor Manufacturing
• Optical Lithography
• Integrated Circuit Fabrication

Background:

• Immersion deep ultraviolet (DUV) lithography is vital for sub-10 nm feature patterning in advanced integrated circuits.
• Dynamic instabilities in DUV light sources (spectral, coherence, energy) degrade imaging performance, affecting contrast, NILS, and CD uniformity.

Purpose of the Study:

• To quantitatively model the impact of laser parameter fluctuations on Normalized Image Log-Slope (NILS) and Critical Dimension (CD) uniformity.
• To evaluate the influence of multi-parameter laser instabilities in immersion DUV lithography.

Main Methods:

• Established systematic physical models for imaging perturbations caused by laser output instabilities.
• Utilized simulations to assess the influence of laser parameter variations on line/space (L/S) and tip-to-line (T2L) structures.
• Validated the proposed perturbation model through imaging fidelity evaluations.

Main Results:

• Spectral attributes, coherence variations, and pulse energy instability collectively degrade NILS and amplify CD variation.
• Pulse energy fluctuation has a greater impact on imaging errors than bandwidth and wavelength variations at advanced nodes.
• Pulse energy fluctuations must be confined within 1% for 45 nm linewidths to meet the 10% process window requirement.

Conclusions:

• Laser instabilities compromise pattern fidelity and chip yield in advanced DUV lithography.
• Provides theoretical foundations for dynamic stability control of light sources.
• Offers practical insights for process optimization in next-generation DUV lithography.