Patent Landscape for Electron Emitting Nanomaterials

I recently published an article in the Nanotechnology Law and Business Journal (http://www.nanolabweb.com/) exploring the U.S. patent landscape for electron emitting nanomaterials. These materials represent an early area of commercialization for nanotechnology in the electronics area and have already been the source of some legal conflicts (Nano-Proprietary v. Canon lawsuit). Some of the currently proposed applications that use these materials include flat panel displays, lighting devices, microwave electronics, and lithography tools. The article discusses why nanomaterials are beneficial for these applications as well as the major patent holders for these nanomaterials.

For those interested in the patent data for these nanomaterials that I used in writing this article(Excel spreadsheet containing 300 patents sorted according to assignee and application area) send an E-mail to blaise_mouttet@yahoo.com with nanomaterial database in the title.

US Patent 7276844 - Photoimagable CNT field emitter paste

http://www.freepatentsonline.com/7276844.html

In order to mass produce field emission displays using carbon nanotubes it may be necessary to integrate CNT processing with current semiconductor manufacturing methods. This patent from du Pont teaches the use of a paste that includes both carbon nanotubes and photosensitive material to facilitate photopatterning of CNT electron emitters. Claim 1 reads:

1. A field emitter cathode comprising (a) a substrate, and (b) a field emitter cathode paste composition comprising a composition of carbon nanotubes, particles and one or more members of the group consisting of a photoinitiator, a developable binder and a photohardenable monomer.

US Patent 7247980 - CNT/Diamond electron emitter paste

http://www.freepatentsonline.com/7247980.html

Carbon nanotubes are very efficient electron emitters with emission occurring at fields of about 1 V/micron to produce current densities over 1 A/cm2. However, when mixed with paste to form a film the efficiency is decreased. This patent focused on an optimized emitter paste using carbon nanotubes, diamond and other components. Claim 1 reads:

1. An emitter paste composition of a field emission cell, comprising 2 wt % to 20 wt % of a carbon nanotube, a binder, glass frit, a dispersing agent, an organic solvent, and 0.1 wt % to 20 wt % of diamond, based on a weight thereof.

US Patent 7239074 - Carbon nanotube field emitters formed in recess

http://www.freepatentsonline.com/7239074.html

Various constructions have been proposed and implemented by companies such as Nanoproprietary, Samsung, and others for forming large arrays of carbon nanotube electron emitters to enable applications in flat panel displays. Usually the fabrication of these emitter arrays requires several steps of depositing and patterning insulating films formed on a conductive or semiconductive substrate and subsequently etching the insulating film to prepare barriers and wells in which the emitters can be formed. This patent from Hon Hai Precision of Taiwan teaches a simplified fabrication process which avoids several deposition and etching steps by using an insulating substrate with a recess formed therein as a starting material. Claim 1 reads:

1. A field emission device comprising: an insulative substrate, the substrate defining a recess therein; and a cathode with a plurality of electron emitters formed thereon, the cathode being positioned in the recess.

US Patent 7239073 - New carbon structure for electron emission

http://www.freepatentsonline.com/7239073.html

Several different carbon-based nanomaterials have been proposed and implemented in electron emitting devices including fullerenes, carbon nanotubes, and nanocrystalline diamond. Energy efficiency is achieved by using these materials due to the low threshold voltages necessary to achieve emission. In addition the materials can be coated or patterned to cover large area substrates so as to enable surface emission electronic devices for applications such as flat panel displays and massively parallel electron beam lithography. This patent from Futaba Corp. proposes another new type of carbon structure that includes nanosized extensions from a microscale body to further enhance emission from a substrate on which the carbon structures are formed. Claim 1 reads:

1. A carbon substance comprising: a structure having a diameter ranging from about 1 micron to about 100 microns and including carbon and a metal or a metallic oxide; and a plurality of line-shaped bodies whose diameters are smaller than about 200 nm, wherein the line-shaped bodies include carbon as a main component thereof and grow radially from a surface of the structure; and wherein the structure has a curved shape of sphere, hemisphere, ellipse or half ellipse.

US Patent 7233101 - Steerable nanowire E-beams

http://www.freepatentsonline.com/7233101.html

Electron emitting nanomaterials such as carbon nanotubes and nanocrystalline diamond are finding many applications in flat panel displays, x-ray sources, microwave amplifiers, and E-beam lithography. Some of the key advantages of using nanomaterials for electron emission are:

a) there is a low threshold voltage necessary for the emission which can lead to more energy efficient products (example: cell phones using field emission based displays would require less frequent charging)

b) these materials are gradually being integrated with semiconductor processing methods and circuits which can ultimately reduce cost and size of any products using E-beams for their operation (example: handheld electron microscopes)

c) high density arrays of electron emitters are able to be formed from nanostructures allowing for parallel processing which can make certain applications operate more quickly (example: E-beam lithography, which is primarily limited due to the serial nature of scanning the E-beam, can be tremendously enhanced by the use of closely spaced carbon nanotube emitters working in parallel)

This patent from Samsung is directed to the individual positioning control of parallel arrays of nanowire field emitters. Claim 1 reads:

1. A substrate-supported array of spaced-apart nanowires comprising: a substrate; and disposed upon the substrate a plurality of spaced-apart, aligned and individually steerable nanowires having a ratio of a nanowire spacing to a nanowire height of at least 0.2 and a nanowire diameter in the a range of 1 500 nanometers, wherein the nanowire height is in a range of 0.1 to 200 micrometers, and a ratio of the nanowire height to the nanowire diameter is between approximately 4,500 and 10,000.

US Patent 7220971 - Nanotube field emitters used in biological processing

http://www.freepatentsonline.com/7220971.html

Irradiation of biological cells is used in analyzing the radiation risks in cancer therapy. This patent from the University of North Carolina teaches using nanotubes as electron emitters to provide selective irradiation of cells. Claim 1 reads:

1. A method for selectively irradiating target biological cells, the method comprising: (a) providing a plurality of individually controllable electron field emitters; (b) providing an electrode operable to extract electrons from the electron field emitters; (c) determining target biological cells for irradiation; (d) identifying locations of the determined target biological cells; and (e) individually controlling electron extraction from each of the electron field emitters to selectively irradiate the identified locations for irradiating the determined target biological cells.

US Patent 7220159 - E-beam convergence in nanotube field emitter

http://www.freepatentsonline.com/7220159.html

An early commercialization area for carbon nanotubes is field emission displays. Substantial patenting has already been done by Samsung, Canon, Nanoproprietary and other companies in this area and continued efforts look toward further applications of nanotube field emission for microwave electronics and massively parallel e-beam lithography. This patent focuses on a manufacturing method used to form an integrated converging mechanism for nanotube generated focused electron beams. Claim 1 reads:

1. A manufacturing method for a converging-type cathode of a field-emission display, comprising the following steps in the order named: a) providing a substrate of the cathode; b) forming a first electrode layer on the substrate; c) forming a second electrode layer composed of a plurality of electron emission sources on the first electrode layer; d) forming a third electrode layer directly on the first electrode layer, the third electrode encircling each electron emission source of the second electrode layer and having a height higher than that of the second electrode layer; e) sintering the first, second and third electrode layers on the substrate.