Nitrogen-rich silicon nitride thin films for deep-ultraviolet Mirau interferometry

Area of Science:

• Materials Science
• Optics
• Microscopy

Background:

• Standard nitride thin films often exhibit high stress and limited UV transparency.
• Developing UV-transparent materials is crucial for advanced optical applications.

Purpose of the Study:

• To investigate UV-transparent nitride thin films for optical applications.
• To optimize thin-film composition for enhanced UV transparency and manageable stress.
• To demonstrate the utility of these films in microfabricating optical devices.

Main Methods:

• Low-pressure chemical-vapor-deposition (LPCVD) of nitride thin films.
• Fabrication of nitrogen-rich and silicon-rich thin-film membranes.
• Characterization of UV transparency and film stress.
• Microfabrication of a UV Mirau interferometer.

Main Results:

• Nitrogen-rich nitride thin films achieved over 95% UV transparency below 250 nm.
• Film stress was maintained at manageable levels, below giga-Pascal range.
• Successful microfabrication of a UV Mirau interferometer was demonstrated.

Conclusions:

• Nitrogen-rich nitride thin films are a promising material for UV transparent applications.
• These films enable the development of novel optical microdevices.
• The developed interferometer is suitable for correlation microscopy in the UV spectrum.