Patent US2384234A successfully refreshed from Google Patents.
Patent EP0306173A1 successfully refreshed from Google Patents.
EP0306173A1
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EP
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Field emission devices
Assignee: The General Electric Company PLC
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Filing: 1988-08-15
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Granted: —
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Expires: 2008-08-15
Abstract
Abstract In a method of forming a field-induced emission device, a cathode (3) is provided on a substrate (4), for example by etching away the substrate to leave a pointed projection. The projection may be covered with a metallic layer (5) to enhance the field-induced cathode emission. A first insulating layer (7) is formed over the substrate, with an aperture therein corresponding to the cathode position. An apertured control grid layer (9) is formed over the first insulating layer and an apertured second insulating layer (15) is formed thereon. A tunnel (18) formed by the apertures in the insulating and conductive layers is filled with a plug (19) of soluble material. An anode strip (21) is formed on the second insulating layer (15) and over the plug, and the plug is then dissolved through gaps at the edges of the anode strip, thereby leaving an unsupported area of anode strip over the cathode. The tunnel (18) may then be evacuated or may be filled with gas and the gaps at the edges of the anode strip will then be sealed to retain the vacuum or gas. If a diode structure is required, the control grid layer and the second insulating layer will be omitted. A switching device may be constructed by associating a number of the cathodes on the substrate with a common control grid and a common anode. The anode, grid and cathode structures may be so dimensioned as to form a transmission line.
Inventors
- 👤 Rosemary Ann Lee
- 👤 Nandasiri Samarakone
- 👤 Neil Alexander Cade
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 16:08
CPC Classifications
H; H01; H01J; H01J21/00; H01J21/02; H01J21/06; H01J21/10; H01J21/105; H01J1/00; H01J1/02; H01J1/30; H01J1/304; H01J1/3042; H01J9/00; H01J9/02; H01J9/022; H01J9/025
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
94 words
A method of forming a field-induced emission device, characterised by forming a cathode body (3) on a substrate (1); forming thereover an electrically-insulating layer (7) having an aperture (18) therein through which the cathode body is revealed; filling the aperture with a plug (19) of soluble material; forming a strip (21) of electrically-conductive material on the insulating layer and extending across the plug; and dissolving the plug from beneath the conductive strip to leave a portion of the strip suspended across the aperture and spaced from the cathode body, to act as an anode.
Claim 2
Independent Claim
94 words
A method of forming a field-induced emission device, characterised by forming a cathode body (3) on a substrate (1); forming thereover an electrically-insulating layer (7) having an aperture (18) therein through which the cathode body is revealed; filling the aperture with a plug (19) of soluble material; forming a strip (21) of electrically-conductive material on the insulating layer and extending across the plug; and dissolving the plug from beneath the conductive strip to leave a portion of the strip suspended across the aperture and spaced from the cathode body, to act as an anode.
Claim 3
Dependent Claim
28 words
A method as claimed in Claim 1, characterised in that the cathode body (3) is formed by selectively etching away part of the thickness of the substrate (1).
Claim 4
Dependent Claim
26 words
A method as claimed in Claim 1 or Claim 2, characterised in that the cathode body (3) tapers in a direction away from the substrate (4).
Claim 5
Independent Claim
31 words
A method as claimed in any preceding claim, characterised in that at least one metallic layer (5) is deposited over the cathode body (3) before deposition of the insulating layer (7).
Claim 6
Independent Claim
20 words
A method as claimed in any preceding claim, characterised in that the plug (19) is formed of a photo-sensitive material.
Claim 7
Independent Claim
35 words
A method as claimed in any preceding claim, characterised in that an electrically-conductive layer (9) is formed between the substrate (4) and the conductive strip (21) and insulated therefrom to act as a control electrode.
Claim 8
Dependent Claim
48 words
A method as claimed in Claim 6, characterised in that the conductive layer (9) is provided with an aperture (13) therethrough, substantially in alignment with the aperture (14) in the insulating layer (7), whereby the edge of the conductive layer around its aperture acts as the control electrode.
Claim 9
Dependent Claim
33 words
A method as claimed in Claim 7, characterised in that a plurality of said electrically-conductive layers are provided before the conductive strip (21) is formed, each conductive layer forming a separate control electrode.
Claim 10
Dependent Claim
40 words
A method as claimed in Claim 8, characterised in that the apertures through the electrically-conductive layers overlap each other but are mutually staggered so that there is no direct line-of-sight path between the anode (21) and the cathode body (3).
Claim 11
Independent Claim
23 words
A method as claimed in any one of Claims 6-9, characterised in that the or each conductive layer (9) is formed of polysilicon.
Claim 12
Dependent Claim
23 words
A method as claimed in Claim 10, characterised in that after deposition of the polysilicon layer (9), doping of the polysilicon is effected.
Claim 13
Independent Claim
35 words
A method as claimed in any preceding claim, characterised in that the dissolved plug material leaves the aperture (18) via at least one gap (22,23) between the conductive strip (21) and the insulating layer (7,15).
Claim 14
Dependent Claim
50 words
A method as claimed in Claim 12, characterised in that, after removal of the dissolved plug material, the aperture (18) vacated by the plug (19) is evacuated or gas-filled, and the or each gap (22,23) is sealed by an additional layer (24) formed thereover to retain the vacuum or gas.
Claim 15
Dependent Claim
90 words
A field-induced emission device, characterised by a substrate (4); a cathode body (3) formed on the substrate; an electrically-insulating layer (7) deposited over the substrate and having an aperture (18) therethrough through which the cathode body is revealed; and a strip (21) of electrically-conductive material supported by the insulating layer and extending across the aperture and spaced from the cathode body, to act as an anode; wherein the cathode body is structured for field-induced electron emission therefrom at an anode-cathode voltage less than will cause breakdown of the insulating layer.
Claim 16
Dependent Claim
90 words
A field-induced emission device, characterised by a substrate (4); a cathode body (3) formed on the substrate; an electrically-insulating layer (7) deposited over the substrate and having an aperture (18) therethrough through which the cathode body is revealed; and a strip (21) of electrically-conductive material supported by the insulating layer and extending across the aperture and spaced from the cathode body, to act as an anode; wherein the cathode body is structured for field-induced electron emission therefrom at an anode-cathode voltage less than will cause breakdown of the insulating layer.
Claim 17
Dependent Claim
32 words
A device as claimed in Claim 14, characterised by an electrically-conductive layer (9) disposed between the substrate (4) and the conductive strip (21) and insulated therefrom to act as a control electrode.
Claim 18
Dependent Claim
47 words
A device as claimed in Claim 15, characterised in that the conductive layer (9) has an aperture (13) therethrough substantially in alignment with the aperture (1) in the electrically-insulating layer (7), whereby the edge of the conductive layer (9) around its aperture acts as the control electrode.
Claim 19
Dependent Claim
34 words
A device as claimed in Claim 14, characterised by a plurality of spaced-apart electrically-conductive layers disposed in a stack between the substrate (4) and the conductive strip (21) to act respectively as control electrodes.
Claim 20
Dependent Claim
60 words
A device as claimed in Claim 17, characterised in that each electrically-conductive layer has an aperture for the passage of electrons therethrough in flowing between the cathode body (3) and the anode (21); and wherein the successive apertures in the stack are offset relative to each other to avoid a direct line-of-sight path between the anode and the cathode body.
Claim 21
Independent Claim
26 words
A device as claimed in any one of Claims 14-18, characterised in that the cathode body (3) tapers in a direction away from the substrate (4).
Claim 22
Independent Claim
31 words
A device as claimed in any one of Claims 14-19, characterised in that the or each said aperture (18) is evacuated or gas-filled and the vacuum or gas is sealed therein.
Claim 23
Dependent Claim
137 words
A switching device, characterised by a substrate (26); a plurality of cathode bodies (27) formed on the substrate; an electrically-insulating layer (29) deposited over the substrate and having a plurality of apertures therethrough through which the cathode bodies are revealed; a strip (28) of electrically-conductive material supported by the insulating layer to act as a control electrode and having apertures therein corresponding to the apertures in said insulating layer; and a layer (30) of electrically-conductive material spaced from the control electrode to act as an anode; wherein the substrate, the control electrode and the anode are so dimensioned and spaced as to form at least a section of a transmission line; and wherein the cathode bodies are structured for field-induced electron emission therefrom at a cathode-control electrode voltage less than will cause breakdown of the insulating layer.
Claim 24
Dependent Claim
137 words
A switching device, characterised by a substrate (26); a plurality of cathode bodies (27) formed on the substrate; an electrically-insulating layer (29) deposited over the substrate and having a plurality of apertures therethrough through which the cathode bodies are revealed; a strip (28) of electrically-conductive material supported by the insulating layer to act as a control electrode and having apertures therein corresponding to the apertures in said insulating layer; and a layer (30) of electrically-conductive material spaced from the control electrode to act as an anode; wherein the substrate, the control electrode and the anode are so dimensioned and spaced as to form at least a section of a transmission line; and wherein the cathode bodies are structured for field-induced electron emission therefrom at a cathode-control electrode voltage less than will cause breakdown of the insulating layer.
Claim 25
Dependent Claim
49 words
A device as claimed in Claim 21, characterised in that the anode (30) and the cathode bodies (27) are electrically interconnected, whereby the switching device is rendered conductive by a signal which is to be switched and which is applied between the control electrode (28) and the anode/cathode circuit.
Claim 26
Dependent Claim
55 words
A switching device as claimed in Claim 21, characterised by a second insulating layer (33) which is apertured such that a plurality of the cathode bodies (39) are associated with the or each aperture (36), whereby the or each aperture provides an emission path from the associated plurality of cathode bodies to the anode (34).
References Cited (Backward Citations)
US4008412A
Cited
US4578614A
Cited
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