New immersion-lithography technique halves polarizer period

Jan. 1, 2011
Immersion lithography at ultraviolet (UV) wavelengths has been used extensively to create wire-grid polarizers consisting of parallel lines of aluminum or some other metal on an optically transparent substrate.

Immersion lithography at ultraviolet (UV) wavelengths has been used extensively to create wire-grid polarizers consisting of parallel lines of aluminum or some other metal on an optically transparent substrate. To date, the period or "pitch" of these lines is limited to around 140 nm for visible-light applications using a 365 nm source. But a new immersion-lithography technique developed by Glenn Hutchinson, senior R&D officer at FFCP Consultants (Highland, UT), cuts the period in half to 70 nm, resulting in improved contrast ratio and operation at shorter wavelengths (into the UV) for these wire-grid polarizer devices.

In the frequency-doubling technique, a polarized 365 nm source is passed through a spatial filter and then divided (using a beamsplitter) just prior to the target substrate. The two beams are then overlapped and intersected to produce a ribbed pattern in the photoresist. Careful etching prevents the ribs from collapsing on each other and anisotropically transfers the mask rib pattern down to the underlying metal. Utmost attention must be paid to the gas composition, bias powers, and etch times to reduce the etch rate. Optical properties are almost exclusively determined by this etch step. Passivation of the metal wires is then needed to maintain integrity of the polarizer structure. Contact Glenn Hutchinson at [email protected].

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

Sponsored Recommendations

March 31, 2025
Enhance your remote sensing capabilities with Chroma's precision-engineered optical filters, designed for applications such as environmental monitoring, geospatial mapping, and...
March 31, 2025
Designed for compatibility with a wide range of systems, Chroma's UV filters are engineered to feature high transmission, superior out-of-band blocking, steep edge transitions...
March 31, 2025
Discover strategies to balance component performance and system design, reducing development time and costs while maximizing efficiency.
March 31, 2025
Explore the essential role of optical filters in enhancing Raman spectroscopy measurements including the various filter types and their applications in improving signal-to-noise...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!