US5267884A — Microminiature vacuum tube and production method

Claim 1

Independent Claim 160 words

A method of producing a microminiature vacuum tube for controlling electron flow in a vacuum between emitter and collector, the method comprising the steps of: providing a substrate with a surface having a crystal structure adapted for receipt of a low resistance compound semiconductor layer, forming a low resistance compound semiconductor layer on the surface of the substrate, the low resistance semiconductor layer defining a plane, forming a recess in the low resistance semiconductor layer and penetrating into the substrate, the recess being formed to define an emitter and a collector in the low resistance layer and providing a direct path in said plane for electron flow from the emitter to the collector, and the forming step providing a sharp-edge at the recess for at least the emitter to enhance the emission of electrons for flow along said path to the collector, and disposing a gate electrode between the emitter and collector and proximate but not projecting into said path.

Claim 2

Independent Claim 160 words

A method of producing a microminiature vacuum tube for controlling electron flow in a vacuum between emitter and collector, the method comprising the steps of: providing a substrate with a surface having a crystal structure adapted for receipt of a low resistance compound semiconductor layer, forming a low resistance compound semiconductor layer on the surface of the substrate, the low resistance semiconductor layer defining a plane, forming a recess in the low resistance semiconductor layer and penetrating into the substrate, the recess being formed to define an emitter and a collector in the low resistance layer and providing a direct path in said plane for electron flow from the emitter to the collector, and the forming step providing a sharp-edge at the recess for at least the emitter to enhance the emission of electrons for flow along said path to the collector, and disposing a gate electrode between the emitter and collector and proximate but not projecting into said path.

Claim 3

Dependent Claim 53 words

The method as set forth in claim 1 in which the step of forming the recess comprises etching a recess through the low resistance semiconductor layer and into the substrate, the step of etching comprising orientation dependent etching along a crystal plane of the substrate oriented to form the sharp-edge of the emitter.

Claim 4

Dependent Claim 71 words

The combination as set forth in claim 1 wherein the steps of providing the low resistance layer and forming a recess comprise depositing an insulator film on the substrate to define the recess, and epitaxially growing a crystal structure including the low resistance semiconductor layer on the substrate, the step of growing comprising growing the crystal structure in a preferential direction adapted to facilitate formation of the sharp-edge of the emitter.

Claim 5

Independent Claim 161 words

A method of producing a microminiature vacuum tube for controlling electron flow in a vacuum between emitter and collector, the method comprising the steps of: providing a compound semiconductor substrate having a low resistance layer on a first planar surface thereof, etching a recess through the low resistance layer and into the substrate such that the recess defines an emitter and a collector in the plane of the low resistance layer, the emitter and collector providing a direct path in said plane for electron flow from the emitter to the collector, forming a gate electrode proximate but not projecting into said path for control of electron flow between the emitter and collector, and performing said etching step in a preferential orientation dependent fashion to produce a sharp-edge in the low resistance layer at the recess for at least the emitter in order to enhance the emission of electrons for flow along said path to the collector under control of the gate.

Claim 6

Independent Claim 161 words

A method of producing a microminiature vacuum tube for controlling electron flow in a vacuum between emitter and collector, the method comprising the steps of: providing a compound semiconductor substrate having a low resistance layer on a first planar surface thereof, etching a recess through the low resistance layer and into the substrate such that the recess defines an emitter and a collector in the plane of the low resistance layer, the emitter and collector providing a direct path in said plane for electron flow from the emitter to the collector, forming a gate electrode proximate but not projecting into said path for control of electron flow between the emitter and collector, and performing said etching step in a preferential orientation dependent fashion to produce a sharp-edge in the low resistance layer at the recess for at least the emitter in order to enhance the emission of electrons for flow along said path to the collector under control of the gate.

Claim 7

Dependent Claim 64 words

The method as set forth in claim 4 in which the semiconductor substrate is a crystalline structure of GaAs, the low resistance layer comprising dopant impurities associated with the first planar surface of the substrate, and the step of etching comprises orienting the crystalline structure such that the (100)-crystalline plane is oriented with the first planar surface thereby to facilitate formation of the sharp-edge.

Claim 8

Dependent Claim 81 words

The method as set forth in claim 4 wherein the step of providing a semiconductor substrate comprises forming a compound semiconductor crystalline substrate layer on an insulator base, and forming a low resistance layer on the surface of the crystalline structure, the low resistance layer comprising dopant impurities associated with first planar surface, and the step of etching comprises etching with a preferential element to expose a (100)-oriented surface as the first planar surface, thereby to facilitate formation of the sharp-edge.

Claim 9

Dependent Claim 33 words

The method as set forth in claim 4 wherein the step of forming a gate electrode comprises depositing a first elongate metallic gate in the recess proximate but not projecting into said path.

Claim 10

Dependent Claim 45 words

The method as set forth in claim 7 wherein the step of forming a gate electrode further comprises forming a second elongate metallic gate in an air bridge over the recess and positioned proximate but not projecting into said path opposite said first elongate gate.

Claim 11

Dependent Claim 35 words

The method as set forth in claim 8 in which the step of etching further comprises forming said sharp-edge in a saw-tooth configuration having a plurality of points directed across the recess toward the collector.

Claim 12

Dependent Claim 35 words

The method as set forth in claim 4 in which the step of etching further comprises forming said sharp-edge in a saw-tooth configuration having a plurality of points directed across the recess toward the collector.

Claim 13

Dependent Claim 33 words

The method as set forth in claim 4 wherein the step of forming the recess comprises forming a microminiature recess of submicron width to minimize voltage requirements for electron emission from the emitter.

Claim 14

Dependent Claim 52 words

The method as set forth in claim 4 further including the step of forming a plurality of said microminiature vacuum tubes in substantially the same planar array, and interconnecting collectors and emitters of selected ones of said plurality of microminiature vacuum tube for forming a plane in an array of said tubes.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1996-12-06	1997-06-07	1997-12-07	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2000-12-06	2001-06-07	2001-12-07	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2004-12-06	2005-06-07	2005-12-07	$7700.00	Window Closed / Lapsed

Microminiature vacuum tube and production method

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