# US 9,748,071 B2 · Individually switched field emission arrays > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,748,071 B2 - Document ID: US9748071B2 - Status: Granted - Kind: B2 - Application number: 14/765,759 - Filed: 2014-02-05 - Published: 2015-12-24 - Granted: 2017-08-29 - Earliest claimed: 2013-02-05 - Assignees: Massachusetts Institute of Technology - Applicants: Massachusetts Institute of Technology - Inventors: Stephen Angelo Guerrera; Akintunde I. Akinwande - Web page: https://patentgrep.com/patent/US9748071B2 ## CPC - H01J 37/073: Electron guns using field emission, photo emission, or secondary emission electron sources - H01J 37/065: Construction of guns or parts thereof (H01J37/067 - H01J37/077 take precedence) - H01J 37/3007: {Electron or ion-optical systems} - H01J 37/3174: {Particle-beam lithography, e.g. electron beam lithography} - H01J 37/3177: {Multi-beam, e.g. fly's eye, comb probe} - H10P 95/00: Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass - H01J 2237/0473: accelerating - H01J 2237/063: Electron sources - H01J 2237/3175: Lithography - H01J 2237/31781: from patterned cold cathode - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract An electron beam apparatus is disclosed that includes a plurality of current source elements disposed in at least one field emitter array. Each current source element can be a gated vertical transistor, an ungated vertical transistor, or a current controlled channel that is proximate to an optically-modulated current source. The electron beam apparatus includes a plurality of field emitter tips, each field emitter tip of the plurality of field emitter tips being coupled to a current source element of the plurality of current source elements. The electron beam apparatus is configured to allow selective activation of one or more of the current source elements. ## Claims ### Claim 1 An electron beam apparatus comprising: a substrate; a plurality of field emitter elements disposed over the substrate in at least one array, each field emitter element of the plurality of field emitter elements comprising: a current channel region disposed at a first end of the field emitter element proximate to the substrate; a donor-doped region or an acceptor-doped region disposed at a second end of the field emitter element that is different from the first end; and a field emitter tip disposed proximate to the second end of the field emitter element; and at least one extraction gate electrode disposed proximate to the plurality of field emitter elements, to apply a potential difference proximate to at least one field emitter tip of the plurality of field emitter elements, thereby accelerating the electrons emitted from the at least one field emitter tip in a direction away from the at least one field emitter tip, wherein each field emitter element of the plurality of field emitter elements further comprises a conductive material surrounding at least a portion of a side of the respective field emitter element. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein each field emitter element of the plurality of field emitter elements has an aspect ratio of height to lateral dimension of about 5:1, about 10:1, about 50:1, about 100:1, about 200:1, about 500:1 about 800:1, about 1000:1, or about 5,000:1. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the plurality of field emitter elements are disposed at a pitch of about 45 microns, about 40 microns, about 30 microns, about 20 microns, about 15 microns, about 10 microns, about 5 microns, about 2 microns, or about 1 micron. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the array is a one-dimensional array, a two-dimensional array, or a staggered three-dimensional array. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein each field emitter tip has a radius of about 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm, about 10 nm, about 12 nm, about 15 nm, or about 20 nm. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the emitted electrons from the plurality of field emitter elements produce an electron beam of brightness about 1×106 A/cm2/sr, 5 ×106 A/cm2/sr, 1×107 A/cm2/sr, 5×107 A/cm2/sr, 1×108 A/cm2/sr, about 5×108 A/cm2/sr, about 1×109 A/cm2/sr, or about 5×109 A/cm2/sr. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein each field emitter element comprises silicon, aluminum, copper, silver, gold, platinum, zinc, nickel, titanium, chromium, palladium, tungsten, molybdenum , diamond, carbon nanofiber, graphene, indium-tin-oxide, or gallium arsenide. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein each field emitter tip comprises an electrically conductive material. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein each field emitter tip comprises a refractory metal, a noble metal, a semiconductor, a semimetal, or a semimetal. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein each field emitter element has a pillar structure, and wherein the pillar structure has a length of about 10 microns and a lateral dimension of about 100 nm. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein a donor-doped region is disposed at the second end of the field emitter element, and wherein a voltage can be applied to the conductive material to regulate an amount of a current flowing through the channel region to the donor-doped region of the respective field emitter element. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the at least one extraction gate electrode is a plurality of extraction gate electrodes, and wherein each extraction gate electrode of the plurality of extraction gate electrodes is disposed proximate to a respective one or more field emitter elements of the plurality of field emitter elements to apply the potential difference proximate to the respective one or more field emitter elements of the plurality of field emitter elements. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein each extraction gate electrode of the plurality of extraction gate electrodes is formed as a conductive material layer including a hollow opening that is disposed proximate to the one or more field emitter tips of the respective one or more field emitter elements. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the conductive material layer is disposed proximate to the respective one or more field emitter elements such that the hollow opening is substantially concentric with a portion of at least one field emitter tip of the respective one or more field emitter elements of the plurality of field emitter elements. ### Claim 15 (depends on 13) The apparatus of claim 13, wherein the hollow opening is substantially circular, substantially oval, or substantially polygonal in shape. ### Claim 16 (depends on 12) The apparatus of claim 12, further comprising at least one electrostatic electrode disposed proximate to the plurality of extraction gate electrodes, to shape the electrons accelerated by the at least one extraction gate electrode into at least one focused electron beam. ### Claim 17 (depends on 16) The apparatus of claim 16 wherein the at least one electrostatic electrode comprises a plurality of electrostatic electrodes, and wherein each electrostatic electrode of the plurality of electrostatic electrodes is disposed proximate to a respective extraction gate electrode of the plurality of extraction gate electrodes. ### Claim 18 (depends on 16) The apparatus of claim 16, wherein the at least one electrostatic electrode is at least one of: an electron focusing lens assembly, an additional extraction gate electrode, an Einzel lens, an acceleration grid, and a stigmation corrector. ### Claim 19 (depends on 1) The apparatus of claim 1, wherein the substrate comprises at least one electrically conductive contact region, and wherein the plurality of field emitter elements are in electrical communication with the at least one electrically conductive contact region of the substrate. ### Claim 20 (depends on 1) The apparatus of claim 1, wherein the substrate comprises at least one logic chip, and wherein the plurality of field emitter elements are in electrical communication with the at least one logic chip. ### Claim 21 (depends on 20) The apparatus of claim 20, wherein a donor-doped region is disposed at the second end of the field emitter element, wherein each field emitter element of the plurality of field emitter elements further comprises a conductive material surrounding at least a portion of a side of the respective field emitter element, and wherein the at least one logic chip controls a current or voltage applied to the conductive material of each field emitter element to regulate an amount of a current flowing through the channel region to the donor-doped region of the respective field emitter element. ### Claim 22 An electron beam apparatus comprising: a substrate comprising an optically modulated current source; a plurality of field emitter elements disposed over the substrate in at least one array, each field emitter element of the plurality of field emitter elements comprising: a current channel region disposed at a first end of the field emitter element proximate to the optically modulated current source; and a field emitter tip disposed proximate to a second end of the field emitter element that is different from the first end; and at least one extraction gate electrode disposed proximate to the plurality of field emitter elements, to apply a potential difference proximate to at least one field emitter tip of the plurality of field emitter elements, thereby accelerating electrons emitted from the at least one field emitter tip in a direction away from the at least one field emitter tip; wherein the optically modulated current source is a P-I-N diode. ### Claim 23 (depends on 22) The apparatus of claim 22, wherein each field emitter element of the plurality of field emitter elements has an aspect ratio of height to lateral dimension of about 5:1, about 10:1, about 50:1, about 100:1, about 200:1, about 500:1, about 800:1, about 1000:1, or about 5,000:1. ### Claim 24 (depends on 22) The apparatus of claim 22, wherein the plurality of field emitter elements are disposed at a pitch of about 45 microns, about 40 microns, about 30 microns, about 20 microns, about 15 microns, about 10 microns, about 5 microns, about 2 microns, or about 1 micron. ### Claim 25 (depends on 22) The apparatus of claim 22, wherein the optically modulated current source generates a current under illumination from electromagnetic radiation. ### Claim 26 (depends on 22) The apparatus of claim 22, wherein the P-I-N diode comprises an acceptor-doped region, a photoactive intrinsic region, and a donor-doped region. ### Claim 27 (depends on 22) The apparatus of claim 22, wherein the at least one extraction gate electrode is a plurality of extraction gate electrodes, and wherein each extraction gate electrode of the plurality of extraction gate electrodes is disposed proximate to a respective one or more field emitter elements of the plurality of field emitter elements to apply the potential difference proximate to the respective one or more field emitter elements of the plurality of field emitter elements. ### Claim 28 (depends on 27) The apparatus of claim 27, wherein each extraction gate electrode of the plurality of extraction gate electrodes is formed as a conductive material layer including a hollow opening that is disposed proximate to the one or more field emitter tips of the respective one or more field emitter elements. ### Claim 29 (depends on 28) The apparatus of claim 28, wherein the conductive material layer is disposed proximate to the respective one or more field emitter elements such that the hollow opening is substantially concentric with a portion of at least one field emitter tip of the respective one or more field emitter elements of the plurality of field emitter elements. ### Claim 30 (depends on 28) The apparatus of claim 28, wherein the hollow opening is substantially circular, substantially oval, or substantially polygonal in shape. ### Claim 31 (depends on 27) The apparatus of claim 27, further comprising at least one electrostatic electrode disposed proximate to the plurality of extraction gate electrodes, to shape the electrons accelerated by the at least one extraction gate electrode into at least one focused electron beam. ### Claim 32 (depends on 31) The apparatus of claim 31 wherein the at least one electrostatic electrode comprises a plurality of electrostatic electrodes, and wherein each electrostatic electrode of the plurality of electrostatic electrodes is disposed proximate to a respective extraction gate electrode of the plurality of extraction gate electrodes. ### Claim 33 (depends on 31) The apparatus of claim 31, wherein the at least one electrostatic electrode is at least one of: an electron focusing lens assembly, an additional extraction gate electrode, an Einzel lens, an acceleration grid, and a stigmation corrector. ### Claim 34 An electron beam apparatus comprising: a plurality of current source elements disposed in at least one array, each current source element of the plurality of current source elements comprising: a gated vertical transistor; an ungated vertical transistor; or a current controlled channel that is proximate to an optically modulated current source; a plurality of field emitter tips, each field emitter tip of the plurality of field emitter tips being coupled to an end of a respective current source element of the plurality of current source elements; and at least one extraction gate electrode disposed proximate to the plurality of current source elements, to apply a potential difference proximate to at least one field emitter tip of the plurality of current source elements, wherein the potential difference accelerates the electrons emitted by at least one field emitter tip of the plurality of field emitter tips in a direction away from the at least one field emitter tip. ### Claim 35 (depends on 34) The apparatus of claim 34, further comprising at least one logic control component in electrical communication with each current source element of the plurality of current source elements. ### Claim 36 The apparatus of 35, wherein the at least one logic control component selectively activates each current source element of the plurality of current source elements to supply electrons to the respective field emitter tip, thereby causing the plurality of field emitter tips to be selectively addressable. ### Claim 37 (depends on 35) The apparatus of claim 35, further comprising at least one conductive interconnect in electrical communication with each current source element and the at least one logic control component. ### Claim 38 (depends on 34) The apparatus of claim 34, wherein the plurality of current source elements are disposed in the at least one array at a pitch of about 45microns, about 40microns, about 30 microns, about 20 microns, about 15 microns, about 10microns, about 5 microns, about 2 microns, or about 1 micron. ### Claim 39 (depends on 34) The apparatus of claim 34, wherein each current source element of the plurality of current source elements has an aspect ratio of height to lateral dimension of about 5:1, about 10:1, about 50:1, about 100:1, about 200:1, about 500:1, about 800:1, about 1000:1, or about 5,000:1. ### Claim 40 (depends on 34) The apparatus of claim 34, wherein each field emitter tip of the plurality of field emitter tips is disposed proximate to the end of the respective current source element that includes a donor-doped region or an acceptor-doped region.