Source: http://www.google.com/patents/US6791248?ie=ISO-8859-1
Timestamp: 2015-01-30 17:25:21
Document Index: 454791286

Matched Legal Cases: ['art 106', 'art 106', 'art 106', 'art 106', 'art 106', 'art 106', 'art 106', 'art 106']

Patent US6791248 - Field emission electron source - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThere is provided a field emission electron source at a low cost in which electrons can be emitted with a high stability and a high efficiency and a method of producing the same. In the field emission electron source, a strong electric field drift part 106 is formed on the n-type silicon substrate on...http://www.google.com/patents/US6791248?utm_source=gb-gplus-sharePatent US6791248 - Field emission electron sourceAdvanced Patent SearchPublication numberUS6791248 B2Publication typeGrantApplication numberUS 10/438,070Publication dateSep 14, 2004Filing dateMay 15, 2003Priority dateSep 25, 1998Fee statusPaidAlso published asCN1182561C, CN1249525A, DE69914556D1, DE69914556T2, EP0989577A2, EP0989577A3, EP0989577B1, US6590321, US20030197457Publication number10438070, 438070, US 6791248 B2, US 6791248B2, US-B2-6791248, US6791248 B2, US6791248B2InventorsTakuya Komoda, Tsutomu Ichihara, Koichi Aizawa, Nobuyoshi KoshidaOriginal AssigneeMatsushita Electric Works, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (16), Non-Patent Citations (9), Referenced by (3), Classifications (15), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetField emission electron sourceUS 6791248 B2Abstract There is provided a field emission electron source at a low cost in which electrons can be emitted with a high stability and a high efficiency and a method of producing the same. In the field emission electron source, a strong electric field drift part 106 is formed on the n-type silicon substrate on the principal surface thereof and a surface electrode 107 made of a gold thin film is formed on the strong electric field drift part 106. And the ohmic electrode 2 is formed on the back surface of the n-type silicon substrate 101. In this field emission electron source 110, when the surface electrode 107 is disposed in the vacuum and a DC voltage is applied to the surface electrode 107 which is of a positive polarity with respect to the n-type silicon substrate 101 (ohmic electrode 2), electrons injected from the n-type silicon substrate 101 are drifted in the strong electric field drift part 106 and emitted through the surface electrode 107. The strong electric field drift part 106 comprises a drift region 161 which has a cross section in the structure of mesh at right angles to the direction of thickness of the n-type silicon substrate 1, which is an electrically conductive substrate, and a heat radiation region 162 which is filled in the voids of the mesh and has a heat conduction higher than that of the drift region 161. Images(13) Claims(14)
an electrically conductive substrate having principal surfaces; a strong electric field drift layer formed on one of the principal surfaces of said electrically conductive substrate, comprising at least a) semiconductor crystal regions formed in a manner to stand up vertically on said one of the principal surfaces of said electrically conductive substrate, and b) interspersed between said semiconductor crystal regions, semiconductor micro-crystal regions having nano-structures with a first insulating film having a thickness smaller than that of a micro-crystal of said semiconductor micro-crystal regions formed on a surface of said micro-crystal; and a surface electrode of a thin conductive film formed on said strong electric field drift layer, wherein when a voltage is applied to make said surface electrode a positive electrode with respect to said electrically conductive substrate, electrons injected from said electrically conductive substrate are drifted in said strong electric field drift layer and are emitted through said surface electrode. 2. The field emission electron source of claim 1, wherein said strong electric field drift layer comprises at least a) drift regions for drifting electrons therethrough and b) heat radiation regions having a heat conductivity better than that of said drift regions, both regions being mixed and distributed uniformly on said one of the principal surfaces of said electrically conductive substrate.
CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation of U.S. application Ser. No. 09/404,656, filed Sep. 24, 1999, now U.S. Pat. No. 6,590,321, the disclosure of which is expressly incorporated by reference herein in its entirety.
In the present invention, said semiconductor crystal is preferably polysilicon. But other single crystal, poly-crystal and amorphous semiconductor, for example, poly-crystal semiconductor of IV group, IV�IV group compound semiconductor such as SiC, III-V group compound semiconductor such as GaAs, GaN and InP, and II-VI group semiconductor such as ZnSe may be used.
First the ohmic electrode 2 is formed on a back surface of the n-type silicon substrate 1, and then an undoped polysilicon layer 3 of about 1.5 μm in thickness is formed on a front surface of the n-type silicon substrate 1 opposite to the back surface, thereby to obtain a structure as shown in FIG. 3A. The polysilicon layer 3 is formed by the use of LPCVD process, using a vacuum of 20 Pa, a substrate temperature of 640 � C., and a floating silane gas at 600 sccm.
Then, by effecting the rapid thermal oxidation (RTO) to the PPS layer 4 and the polysilicon layer 3, a structure shown in FIG. 3C is obtained. Reference numeral 5 in FIG. 3C denotes a part of the polysilicon layer processed by the rapid thermal oxidation and reference numeral 6 denotes a part of the PPS layer processed by the rapid thermal oxidation (hereinafter referred to as RTO-PPS layer 6). The rapid thermal oxidation process was conducted at an oxidation temperature of 900 � C. for the oxidation period of one hour. In this embodiment, since the PPS layer 4 and polysilicon layer 3 are oxidized by the rapid thermal oxidation, the layers can be heated up to the oxidation temperature in several seconds, thus making it possible to suppress entrainment oxidation taking place when charging into a furnace in case the conventional oxidation apparatus of furnace tube type is used.
Then, by effecting the rapid thermal oxidation (RTO) to the porous layer 111 and the semiconductor layer 112, a strong electric field drift part 106 is formed. Thereafter, the surface electrode 107 made of a gold thin film is formed by, for example, deposition on the strong electric field drift part 106, resulting in the structure as shown in FIG. 11C. In FIG. 11C, reference numeral 161 designates aporous layer 111 oxidized by rapid thermal oxidation corresponding to the above-mentioned drift region 161 and reference numeral 162 designates a semiconductor layer 112 oxidized by rapid thermal oxidation corresponding to the above-mentioned heat radiation region 162. That is, the strong electric field drift part 106 is composed of the drift region 161 and the heat radiation region 162 in FIG. 11C. The rapid thermal oxidation process was conducted at an oxidation temperature of 900� C. for the oxidation period of one hour. While the thickness of the surface electrode 107 is about 10 nm in this embodiment, the thickness is not limited to a particular value. While the metal thin film (for example, thin gold film) serving as the surface electrode 107 is formed by evaporation in this embodiment, the method of forming the thin metal film is not limited to evaporation and the thin metal film may be formed by sputtering. The field emission electron source 110 forms a diode with the surface electrode 107 serving as a positive electrode (anode) and the ohmic electrode 102 serving as a negative electrode (cathode). The current which flows when a DC voltage is applied between the positive electrode and the negative electrode is diode current.
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