Large-area, high-resolution pattern replication by the use of a two-aspherical-mirror system.

Area of Science:

• Optics and Photonics
• Materials Science
• Semiconductor Manufacturing

Background:

• Soft-x-ray projection lithography is crucial for advanced semiconductor manufacturing.
• Achieving high throughput and large exposure areas with high resolution remains a challenge.

Purpose of the Study:

• To develop and evaluate a soft-x-ray projection lithography system using multilayer mirrors and aspherical optics.
• To determine the feasibility of achieving a high throughput and large exposure area for microfabrication.

Main Methods:

• Development of a reduction system employing two aspherical-mirror optics.
• Evaluation of aspherical mirror figure errors using a laser interferometer.
• Compensation for aberrations through precise adjustment of mirror positions.

Main Results:

• The root-mean-square (rms) figure errors of the concave and convex mirrors were 8.8 nm and 2.0 nm, respectively.
• These errors were insufficient for achieving a 0.1 µm resolution directly.
• An exposure area exceeding 10 mm × 0.6 mm was successfully demonstrated with fine patterns below a quarter micrometer.

Conclusions:

• The developed soft-x-ray projection lithography system shows promise for high-throughput applications.
• Aberration compensation techniques are effective in mitigating mirror imperfections.
• The system achieved a large exposure area with sub-quarter-micrometer patterning, validating its potential for next-generation lithography.