Effects of object roughness on partially coherent image formation

Area of Science:

• Optical Engineering
• Lithography Technology
• Image Science

Background:

• Partially coherent imaging systems are susceptible to phase perturbations.
• These perturbations can introduce unwanted artifacts into the aerial image.
• Understanding these effects is crucial for high-resolution imaging applications.

Purpose of the Study:

• To investigate the impact of phase perturbations on aerial images in partially coherent systems.
• To quantify the sensitivity of imaging systems to small phase deviations.
• To explore the implications for lithography, specifically line-edge roughness.

Main Methods:

• Utilized a combination of computational simulation and experimental validation.
• Introduced controlled phase perturbations in the object plane.
• Analyzed the resulting aerial images for deformation and artifacts.

Main Results:

• Demonstrated that even minor phase perturbations (as low as lambda/30 root-mean-square) cause visible image deformation.
• Observed significant artifact generation for modest coherence factors (e.g., sigma(c) = 0.4).
• Confirmed the detrimental effect of phase errors on image fidelity.

Conclusions:

• Phase perturbations are a critical factor affecting image quality in partially coherent imaging.
• The study highlights the need for precise phase control in lithographic processes.
• Findings provide insights into managing line-edge roughness and other defects in semiconductor manufacturing.