Ultra-precision fabrication technology based on fusion figuring of surface height and slope profile for EUVL objective lenses

Area of Science:

• Optics Manufacturing
• Precision Engineering
• Surface Metrology

Background:

• Extreme ultraviolet lithography (EUVL) projection lenses require stringent manufacturing tolerances for optimal imaging.
• Current ultra-precision machining lacks explicit 2D surface slope control capabilities.

Purpose of the Study:

• To develop an advanced figuring model for ultra-precision optics manufacturing.
• To enable simultaneous control of surface height and slope accuracy for complex optical components.

Main Methods:

• Proposed a partial derivative exchange decoupling (PDED) method for 2D slope-based figuring (SF) models.
• Developed an innovative fusion figuring (FF) model for dual monitoring of surface height and slope accuracy.
• Conducted simulation and actual manufacturing experiments to compare FF, SF, and height-based figuring (HF) models.

Main Results:

• The FF model demonstrated superior performance over SF and HF models in simulations.
• Actual manufacturing experiments showed FF improved RMS convergence for slope errors by over 20% and height errors by nearly 10% compared to HF.
• Achieved notable convergence in optics machining with the FF model.

Conclusions:

• The fusion figuring model offers a new, ultra-precise, and stable approach for fabricating complex optics.
• This method addresses the critical need for precise control over both surface and slope accuracy in advanced optical systems.
• The research advances ultra-precision machining technology for demanding applications like EUVL.