Tiny interferometer aids holographic lithography in organic thin films

A group of researchers has demonstrated a flexible method of performing holographic lithography patterning on organic semiconductor thin film. A corner-cube interferometer (CCI)--designed by the researchers from the University of Lecce (Lecce, Italy) and the University of Cambridge (Cambridge, England)--performed the lithography and was followed by argon-ion-laser-based etching. The CCI consisted of a substrate holder mounted perpendicular to a l/30 mirror. The spot from an argon-ion laser emitt

Tiny interferometer aids holographic lithography in organic thin films

A group of researchers has demonstrated a flexible method of performing holographic lithography patterning on organic semiconductor thin film. A corner-cube interferometer (CCI)--designed by the researchers from the University of Lecce (Lecce, Italy) and the University of Cambridge (Cambridge, England)--performed the lithography and was followed by argon-ion-laser-based etching. The CCI consisted of a substrate holder mounted perpendicular to a l/30 mirror. The spot from an argon-ion laser emitting at 363.8 nm was aligned so that half the spot illuminated the sample, which in this case was poly (p-phenylene vinylene) on a substrate, and half illuminated the mirror. The portion of the spot on the mirror reflected onto the sample interfering with the direct beam to create the holographic pattern. Rotation of the interferom eter produced multiple exposures of the same pattern at various angles. The scientists say the small difference in the optical paths of the two beams allows fast alignment and provides excellent mechanical and thermal stability. Exposure times of a fraction of a second made the system almost insensitive to vibrations. The researchers created planar arrays of squares, diamonds, triangles, and other shapes with period ranging from 200 nm to more than 1 µm. This method, they say, is an important step toward realizing the next generation of organic devices. Contact F. Cacialli at [email protected]

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