Can we improve the energy efficiency of EUV lithography?

TL;DR

This paper proposes a simplified, low-cost EUV lithography projector that significantly reduces EUV source power and improves resolution, making it suitable for advanced chip manufacturing.

Contribution

A novel two-mirror projector design with simplified illumination that reduces EUV power consumption and enhances resolution for semiconductor lithography.

Findings

EUV source power can be reduced to 20W for 100 wafers/hour.

Achieves a resolution limit of 24 nm with a 20 mm field.

Provides a compact, mechanically stable design suitable for small die chips.

Abstract

This paper discusses a simple, low-cost, highly efficient two-mirror projector with a simplified illumination system. The EUV source power can be reduced by 1/10 compared to the current six-mirror EUV projector system. The required EUV power is 20 watts for process speed of 100 wafers per hour. The proposed in-line projector achieves 0.2 NA (20 mm field) and 0.3 NA (10 mm field), which can be assembled in a cylindrical tube configuration similar to a DUV projector, providing superior mechanical stability and easier assembly/maintenance. The EUV light is introduced in front of the mask through two narrow cylindrical mirrors located on both side of the diffraction cone, providing average normal illumination and reducing the mask 3D effect. The simplified illumination system provides symmetric quadrupole off-axis illumination, bypassing central obscuration and improving spatial resolution, also realizing K\"ohler illumination. The theoretical resolution limit is 24 nm (20 mm field), image reduction factor x5 and object image distance (OID) 2000 mm. With the curved surface mask, the tool height can be reduced to (OID) 1500 mm, which provides resolution 16 nm (10 mm field). It will be suitable for small die size chip production for mobile applications as well as the latest chiplet technology.