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Facile Patterning of Conductive Layer

IP.com Disclosure Number: IPCOM000129241D
Publication Date: 2005-Oct-03
Document File: 3 page(s) / 170K

Publishing Venue

The IP.com Prior Art Database

Abstract

Cost-effective patterning of conductive layers as electrodes and interconnects is central to achieving the low- cost economic benefits of organic electronics. Traditional photolithographic technique is too costly, and is not therefore suitable for low-cost organic electronics. There is a need to develop simple methods to pattern conductive layers. In this invention, we demonstrate an easy patterning technique for conductive layers. First, a conductive film was formed on a substrate, and a patterned mask was placed on top of the conductive film. A piece of Scotch™ tape was used to remove the unwanted conductive materials through the mask, resulting in patterned conductive features on the substrate when the mask is removed. Organic thin-film transistors (OTFTs) using patterned gold contacts of this nature had exhibited similar transistor characteristics as those employed vacuum deposited gold electrodes.

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Facile Patterning of Conductive Layer

Cost-effective patterning of conductive layers as electrodes and interconnects is central to achieving the low- cost economic benefits of organic electronics.  Traditional photolithographic technique is too costly, and is not therefore suitable for low-cost organic electronics.  There is a need to develop simple methods to pattern conductive layers.

In this invention, we demonstrate an easy patterning technique for conductive layers.  First, a conductive film was formed on a substrate, and a patterned mask was placed on top of the conductive film.  A piece of ScotchÔ tape was used to remove the unwanted conductive materials through the mask, resulting in patterned conductive features on the substrate when the mask is removed.  Organic thin-film transistors (OTFTs) using patterned gold contacts of this nature had exhibited similar transistor characteristics as those employed vacuum deposited gold electrodes.

Patterning conductive layers as gate, source, and drain electrodes for organic thin film transistors is very important for low-cost, large-area flexible electronics.  Traditional photolithographic technique is too costly, and is not suitable for low cost organic electronics.

Here we propose a very simple method to pattern conductive layer for organic electronics.  The concept is schematically illustrated in Figure 1.

 

First, a mask containing desired patterns was placed on top of the conductive layer which can be formed by any suitable means on a substrate.  An adhesive layer such as a ScotchÔ tape was laid on top of the mask and properly pressed against the mask such that the exposed conductive material could be lifted off and removed.  The result was the formation of the desired conductive patterns on the substrate after removal of the mask.

To reduce this concept to practice, we used a dispersion of gold nanoparticles to form a conductive layer.  A dispersion of gold nanoparticles in cyclohexane (5 wt%) was spin coated on a silicon wafer substrate.  The film was dried at room temperature, and then annealed at 140 °C under vacuum to convert the gold nanoparticles into conductive gold film.

Patterning the continuous gold thin film was conducted in the following manner.  A thin gold film was first deposited on a substrate such as a silicon wafer by conventional deposition techniques (e.g., liquid printing or vacuum evaporation), and a shadow mask with a thickness of 13 micron was placed on top of the gold film.  A piece of ScotchÔ tape was then gently pressed onto the mask to make contact with the gold film through the openings of the mask.  Subsequently, the mask...