Numerical simulation of nanolithography with the subwavelength metallic grating waveguide structure

Area of Science:

• Nanophotonics and Plasmonics
• Lithography Techniques
• Waveguide Theory

Background:

• Subwavelength metallic gratings are crucial for advanced lithography.
• Exciting waveguide modes, particularly coupled surface plasmons, enables high-resolution patterning.
• Existing methods face limitations in achieving nanoscale resolution with visible light.

Purpose of the Study:

• To design and analyze a subwavelength metallic grating waveguide structure for high-resolution lithography.
• To investigate the excitation of waveguide modes, especially coupled surface plasmons, for sub-50nm patterning.
• To compare the performance of metal-layer and metal-cladding schemes for lithography pattern generation.

Main Methods:

• Utilizing metallic waveguide theory for structure design.
• Employing the Finite Difference Time Domain (FDTD) method for performance analysis.
• Investigating two schemes: metal-layer and metal-cladding, analyzing mode excitation and pattern generation.

Main Results:

• The metal-layer scheme uses multiple modes to achieve varying resolutions and visibility.
• The metal-cladding scheme excites coupled modes, yielding higher resolution (~34nm) with comparable visibility.
• Analysis of grating period deviation ensures pattern effectiveness for lithography.

Conclusions:

• The subwavelength metallic grating waveguide is effective for sub-50nm lithography.
• The metal-cladding scheme offers superior resolution compared to the metal-layer scheme.
• Optimizing grating period is essential for maintaining lithographic pattern quality.