US5817201A — Method of fabricating a field emission device

Claim 1

Independent Claim 106 words

A method for fabricating a field emission device, said method comprising the steps of: a) using a first substrate, b) creating resistive molded bases for tapered emissive tips in a mold attached to the first substrate, c) depositing a conductive layer on the mold and the bases of the ties therein, d) bonding said conductive layer to a second substrate, e) removing said first substrate and portions of the mold to leave the bases of the tapered tips in similarly tapered cavities, and f) metallizing said second substrate, with a gate electrode and the apex of said tips in said cavities in a single metallization step.

Claim 2

Independent Claim 106 words

A method for fabricating a field emission device, said method comprising the steps of: a) using a first substrate, b) creating resistive molded bases for tapered emissive tips in a mold attached to the first substrate, c) depositing a conductive layer on the mold and the bases of the ties therein, d) bonding said conductive layer to a second substrate, e) removing said first substrate and portions of the mold to leave the bases of the tapered tips in similarly tapered cavities, and f) metallizing said second substrate, with a gate electrode and the apex of said tips in said cavities in a single metallization step.

Claim 3

Dependent Claim 158 words

The method for fabricating a field emission device according to claim 1, wherein: step a includes: coating said first substrate with a first dielectric layer and subsequently with a second dielectric layer of a different material than the first dielectric layer; step b includes: creating said molds for the tips in said second dielectric layer using an appropriate patterned photoresistive layer in combination with a wet or dry etching process and an etch-stop on said first dielectric layer; recoating said first substrate with a third dielectric layer said dielectric layer of the same material as the first dielectric layer; coating said first substrate with a first conductive layer which is a resistive layer; and partially etching back said first conductive layer, and subsequently coating said first substrate with a low-ohmic second conductive layer; step e includes: removing at least partially said third dielectric layer; and step f includes: coating said remaining second substrate with a second conductive layer.

Claim 4

Dependent Claim 128 words

In the fabrication of a field emission device, the method comprising: a) molding in a mold an array of tapered resistive bases of the field emission devices, each base element having a base end and an apex end; b) attaching the base ends of the molded resistive bases to cathode conductors for the field emission devices; c) forming cavities in the mold around the molded resistive bases which cavities have openings at the apex ends of the molded resistive bases through one surface of the mold; and d) depositing a conductive layer on one surface of the mold and through the openings of said cavities onto the apex ends of the molded resistive base elements to form both gate electrodes and emissive tips of the field emission devices.

Claim 5

Dependent Claim 128 words

In the fabrication of a field emission device, the method comprising: a) molding in a mold an array of tapered resistive bases of the field emission devices, each base element having a base end and an apex end; b) attaching the base ends of the molded resistive bases to cathode conductors for the field emission devices; c) forming cavities in the mold around the molded resistive bases which cavities have openings at the apex ends of the molded resistive bases through one surface of the mold; and d) depositing a conductive layer on one surface of the mold and through the openings of said cavities onto the apex ends of the molded resistive base elements to form both gate electrodes and emissive tips of the field emission devices.

Claim 6

Dependent Claim 33 words

The method of claim 3 wherein step c) includes shaping the cavities to prevent shorting of the emissive layers to the cathode conductors during the depositing of the conductive layer in step d).

Claim 7

Dependent Claim 41 words

The method of claim 4 wherein the shaping of the cavities in step c) includes tapering the sidewalls of the cavity so that the cavities are larger at the base end than at the apex ends of the molded resistive bases.

Claim 8

Dependent Claim 41 words

The method of claim 4 wherein the shaping of the cavities in step c) includes: providing a floor of insulating material for the cavities through which the molded resistive base elements are set to make electrical contact to the cathode conductors.

Claim 9

Dependent Claim 46 words

The method of claim 4 including the step of: e) encapsulating the field emission device produced by steps a) through d) in an enclosure with a phosphorous elements on an interior surface of a glass face of the enclosure opposing the apexes of the molded bases.

Claim 10

Dependent Claim 27 words

The method of claim 4 including the step of f) forming an anode on said surface of the enclosure between said interior surface and said phosphorous elements.

Claim 11

Dependent Claim 26 words

The method of claim 3 wherein step a) includes molding said resistive molded bases of a material from the group comprising polysilicon, germanium, gallium arsenide material.

Claim 12

Dependent Claim 26 words

The method of claim 3 wherein in step c) the depositing of the conductive layer includes depositing one material from the group comprising W and Mo.

Claim 13

Dependent Claim 27 words

The method of claim 3 wherein step a) includes molding said resistive molded bases of material from the group comprising low and nondoped amorphous and polycrystalline silicon.

Claim 14

Dependent Claim 164 words

In the manufacture of a field emission device in which tapered tips with emissive coatings are each mounted on a stripe of a first set of conductive stripes attached to a substrate and are positioned in cavities of an insulating layer having on a surface thereof a second set of conductive stripes orthogonally oriented to the first set of conductive stripes, which second set of conductive stripes have apertures that are located over the cavities at intersections of conductive stripes of said first and second sets, the method comprising: forming resistive bases for the tapered tips out of molded resistive elements and depositing an electron-emitting coating of the same material to both the apex of those bases and to the second set of stripes in the same deposition step so that the stripes of the second set of conductive stripes and the emissive coating on the tips in the apertures therein are electrically and physically separated parts of the same layer of conductive material.

Claim 15

Dependent Claim 164 words

In the manufacture of a field emission device in which tapered tips with emissive coatings are each mounted on a stripe of a first set of conductive stripes attached to a substrate and are positioned in cavities of an insulating layer having on a surface thereof a second set of conductive stripes orthogonally oriented to the first set of conductive stripes, which second set of conductive stripes have apertures that are located over the cavities at intersections of conductive stripes of said first and second sets, the method comprising: forming resistive bases for the tapered tips out of molded resistive elements and depositing an electron-emitting coating of the same material to both the apex of those bases and to the second set of stripes in the same deposition step so that the stripes of the second set of conductive stripes and the emissive coating on the tips in the apertures therein are electrically and physically separated parts of the same layer of conductive material.

Claim 16

Dependent Claim 41 words

The method of claim 12 including providing a negative slope to the sidewalls of the cavities so that the cavities are larger near the bases of the tips than they are near the apex of the tips containing the emissive coating.

Claim 17

Dependent Claim 136 words

The method for fabricating field emission devices according to claim 12, wherein: said first substrate is a material from the group consisting of a polymer, a glass and a silicon substrate, said first dielectric layer is a material from the croup consisting of Si 3 N 4 and a polymer, said second dielectric layer is a SiO 2 -layer, said third dielectric layer is a Si 3 N 4 -layer, said first conductive layer has a high resistivity no- or low-doped polycrystalline silicon forming a serial resistor, said second substrate is a glass substrate, said first substrate is removed mechanically, chemically or by laser irradiation, said third dielectric layer is at least partially removed by chemical etching, and said second conductive layer is a low work function material from the group consisting of W and Mo.

Claim 18

Dependent Claim 43 words

The method of claim 12 including providing said cavities with a floor of insulating material into which the resistive bases of the tips are set with the base ends of the resistive bases exposed therethrough to contact the first set of conductive stripes.

Claim 19

Dependent Claim 43 words

The method of claim 15 including attaching the first set of conductive stripes to the substrate, which is glass, with a low melt point glass bonding layer to thereby provide a glass seal on the substrate to the stripes of the first set.

Claim 20

Dependent Claim 69 words

The method of claim 16 including hermetically sealing a glass face to said substrate to form a vacuumed space containing said tips; providing a conductive coating on said glass face in the vacuumed space facing said tips; and providing phosphorous elements on said conductive coating which in combination with the emissive coatings acts as a light emitting source so that the field emission device forms a flat display panel.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2001-10-05	2002-04-06	2002-10-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2005-10-05	2006-04-06	2006-10-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2009-10-05	2010-04-06	2010-10-06	$7700.00	Window Closed / Lapsed

Method of fabricating a field emission device

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