Anamorphic objective design for extreme ultraviolet lithography at the 5∼1  nm technology node

Area of Science:

• Optical Engineering
• Semiconductor Manufacturing
• Nanotechnology

Background:

• Extreme ultraviolet lithography (EUVL) is crucial for integrated circuit manufacturing at advanced technology nodes (9-7 nm).
• Current EUVL systems use objectives with NA 0.33 and 4x reduction.
• Future nodes (5-1 nm) require higher NA (≥0.55) objectives with anamorphic magnification (8x and 4x).

Purpose of the Study:

• To address the design challenges of high NA objectives for future EUVL nodes.
• To propose a novel anamorphic objective design overcoming conflicting optical and performance requirements.
• To achieve NA 0.55 EUV lithography imaging performance.

Main Methods:

• Implementation of a new anamorphic objective design utilizing free-form surfaces.
• Establishment of a design methodology with manufacturability and high optimization freedom.
• Control of free-form surface coefficients and significant aberration compensation.

Main Results:

• A novel free-form surface anamorphic objective design was successfully implemented.
• The design method allows for controlled surface coefficients and improved aberration correction.
• The designed objective lens meets the stringent imaging performance requirements for NA 0.55 EUV lithography.

Conclusions:

• The developed free-form surface design method enables the realization of high NA anamorphic objectives for advanced EUVL.
• This approach enhances optimization freedom and manufacturability, crucial for next-generation semiconductor lithography.
• The objective design successfully meets the demanding imaging specifications for 5-1 nm technology nodes.