Metrology of replicated diffractive optics with Mueller polarimetry in conical diffraction

Area of Science:

• Optical Metrology
• Nanofabrication
• Diffractive Optics

Background:

• Nanoimprint lithography relies on precise molding tools for fabricating nanostructures.
• Accurate metrology of these tools is crucial for successful replication.
• One-dimensional holographic gratings are key components in nanoimprint molding tools.

Purpose of the Study:

• To investigate the feasibility of using spectroscopic Mueller polarimetry for metrological characterization.
• To assess this technique for the fabrication step of nanoimprint molding tools.
• To analyze both master and replica gratings in the fabrication process.

Main Methods:

• Spectroscopic Mueller polarimetry in conical diffraction was employed.
• Measurements were taken on master gratings (resist on chromium-covered glass) and replica gratings (nickel).
• Grating profiles were fitted from experimental Mueller matrix coefficients at various azimuthal angles.

Main Results:

• The grating profiles derived from Mueller polarimetry data were confirmed by atomic force microscopy (AFM).
• Calculated profiles of master and replica gratings demonstrated complementary characteristics.
• Spectroscopic Mueller polarimetry proved effective in characterizing both grating types.

Conclusions:

• Mueller polarimetry is a viable technique for the metrology of nanoimprint molding tool fabrication.
• It offers a fast and non-contact optical method for characterizing holographic gratings.
• This technique provides a basis for quality control in the nanoimprint lithography process.