Spectroscopic ellipsometry of very rough surfaces

Area of Science:

• Materials Science
• Optical Physics
• Surface Science

Background:

• Spectroscopic ellipsometry is a powerful technique for characterizing thin films and surfaces.
• Analyzing extremely rough surfaces with conventional spectroscopic ellipsometry is challenging due to light scattering.

Purpose of the Study:

• To adapt spectroscopic ellipsometry for surfaces with roughness comparable to or exceeding the wavelength of light.
• To develop a method for accurately determining optical constants of rough materials.

Main Methods:

• Utilized a custom-built spectroscopic ellipsometer.
• Varied the angle of incidence to differentiate between diffusely scattered and specularly reflected light components.
• Analyzed the diffuse scattering component at specular angles.

Main Results:

• Successfully differentiated between diffuse and specular light components.
• Demonstrated that the diffuse component's response mimics that of a smooth surface.
• Achieved accurate optical constant determination for extremely rough surfaces.

Conclusions:

• Measuring the diffuse component at specular angles is beneficial for ellipsometry analysis.
• This approach expands the applicability of spectroscopic ellipsometry to rougher surfaces.
• The findings broaden the scope and utility of spectroscopic ellipsometry.