Grayscale patterning of polymer thin films using direct-write multiphoton photolithography

Reference Number: K 08-33

Inventors: Higgins, Daniel; Ito, Takashi; Yao, Xiao

USPTO Link:

Invention Summary

Due to the limitations of commonly used photo-resist-based lithographic methods, researchers have long sought alternative procedures that can produce high resolution patterns without the use of photomasks and chemical developers. An important additional challenge has been in the creation of grayscale (three-dimensional) surface relief structures.

The present invention pertains to a new laser-based ablative method for fabricating high-resolution binary and grayscale structures in common commercial insulating and electrically-conducting polymers. Ablative lithography has been demonstrated previously in many of these materials. These studies frequently employed nanosecond pulsed UV-to-IR light to drive removal of the polymer film. None demonstrated high-resolution lithography, instead depicting structures tens of micrometers across, with depth resolution on the order of the wavelength of light employed.

High-resolution multiphoton-based photolithography using common photoresist technologies has been demonstrated using different polymers in other reports. These studies also demonstrated that three-dimensional structures could be fabricated. Unfortunately, common positive-tone resists are gradually “exposed” if used in the presence of light and may delaminate from the substrate surface when immersed under liquids (i.e. water).

Advantages

• Grayscale patterning with 1-2 nm depth resolution has been achieved

• High-Resolution binary patterns have been prepared

• Etching technique can be applied to commonly-used commercial polymers

• Etching process does not require use of photomasks or chemical developers

• Etching is driven by irradiation with femtosecond pulses at near-infrared wavelengths

Applications

• Fabricate arrays of microelectrodes and microelectronic circuits for use in chemical sensors, biosensors and biochips

• Fabricate molds having submicron-scale features

• Construct Micro/nanofluidic devices

• Pattern organic electronic circuit components

• Prepare arbitrary grayscale (three-dimensional) computer-generated surface-relief patterns, without any additional development steps and without use of a photomask