US3636397A - Single-crystal silicon carbide display device - Google Patents

Single-crystal silicon carbide display device Download PDF

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US3636397A
US3636397A US815047A US3636397DA US3636397A US 3636397 A US3636397 A US 3636397A US 815047 A US815047 A US 815047A US 3636397D A US3636397D A US 3636397DA US 3636397 A US3636397 A US 3636397A
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wafer
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scribed
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Arrigo Addamiano
Ronald J Perusek
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General Electric Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/26—Materials of the light emitting region
    • H01L33/34—Materials of the light emitting region containing only elements of Group IV of the Periodic Table
    • H01L33/343—Materials of the light emitting region containing only elements of Group IV of the Periodic Table characterised by the doping materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/16—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table
    • H01L29/1608—Silicon carbide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/44—Structure, shape, material or disposition of the wire connectors prior to the connecting process
    • H01L2224/45—Structure, shape, material or disposition of the wire connectors prior to the connecting process of an individual wire connector
    • H01L2224/45001—Core members of the connector
    • H01L2224/45099—Material
    • H01L2224/451—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof
    • H01L2224/45138—Material with a principal constituent of the material being a metal or a metalloid, e.g. boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po), and alloys thereof the principal constituent melting at a temperature of greater than or equal to 950°C and less than 1550°C
    • H01L2224/45144—Gold (Au) as principal constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/484—Connecting portions
    • H01L2224/48463—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
    • H01L2224/48465—Connecting portions the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/30—Technical effects
    • H01L2924/301—Electrical effects
    • H01L2924/3025—Electromagnetic shielding
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/107—Melt
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S148/00—Metal treatment
    • Y10S148/148—Silicon carbide
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S438/00—Semiconductor device manufacturing: process
    • Y10S438/931—Silicon carbide semiconductor

Definitions

  • the display device is a wafer of N-type silicon carbide having lines or segments of lines scribed into one face in a selected design such as an alpha-numeric or a grid of closely spaced dots. After scribing, the wafer is diffused with P-type dopants such as boron and aluminum. Contact to the P-type material within the scribed lines is made by vacuum evaporation of copper-silver.
  • the wafer faces are then lapped to remove the metallizing and P-type layer except within the scribed lines.
  • a connection is then made to the N-type material, and individual connections to each P-type scribed-line segment.
  • line segments By selective energization of line segments, various luminous letters, numerals or characters may be formed which are seen through the N-type material.
  • the invention relates to solid-state subminiature display apparatus utilizing light-emitting junctions in silicon carbide.
  • Light-emitting diodes or solid-state lamps of silicon carbide comprise a junction between n-type material which may be nitrogen doped and p-type material which may be boron and/or aluminum doped.
  • n-type material which may be nitrogen doped
  • p-type material which may be boron and/or aluminum doped.
  • the device is suitably energized by the application of a forward potential across the junction, light is generated by the recombination of charge carriers in close proximity to the junction.
  • a crystal chip containing a PN- junction is mounted P-side down on a header and light is emitted through the N-type top side which is contacted by a fine wire.
  • Solid-state visual display apparatus may be used for displaying symbols including alphabet letters, numerals and symbols of various kinds. Such apparatus is particularly useful in highspeed photographic recording because the response is sub stantially instantaneous.
  • a method of creating lighting patterns in a single crystal of silicon carbide is disclosed which comprises diffusion of dopants into selected zones of the crystal. At the same time diffusion of dopants into other zones is prevented by covering or shielding such other zones by a refractory nonporous material, suitably fragments of silicon carbide crystals.
  • Among the objects of the invention are to provide improved solid-state display apparatus in which the selected designs are clearer and more legible and wherein more information may be conveyed within a given size, and to provide an improved process and technique for creating selected lighting designs in a silicon carbide wafer.
  • the invention provides a solid-state display device consisting of a wafer of N-type silicon carbide having lines or segments of lines scribed into one face and forming a selected design such as an alpha-numeric or a grid of closely spaced dots.
  • the lines are shallow grooves or V-cuts which may be made by a diamond saw.
  • P-type dopants such as boron and aluminum.
  • Contact to the P-type material within the grooves is made by vacuum evaporation of suitable metals such as copper and silver.
  • masking of portions is done prior to the metallizing by vacuum evaporation.
  • An alternative technique suitable for making a grid of closely spaced dots is to cross groove after metallizing.
  • the wafer faces are then lapped to remove the metallizing and P-type layer except in the grooves or V-cuts.
  • Individual connections to each P-type groove segment are then made and a single connection is also made to the N'type material.
  • the luminous design is seen by looking at the grooves through the N-type wafer.
  • FIG. la shows a silicon carbide crystal ground flat and FIG. lb shows a rectangular wafer cut therefrom.
  • FIG. 2 illustrates a diamond saw scribing a line into a wafer.
  • FIG. 3 shows a silicon carbide wafer having an alpha-numeric scribed into one face.
  • FIG. 4 is a cross section through a scribed line on a wafer after P-type diffusion and metal deposition.
  • FIG. 5 shows the same cross section as FIG. 4 after lapping and attachment of a wire lead.
  • FIG. 6 is a pictorial view of an alpha-numeric SiC indicator.
  • FIGS. 70, b, c and d show successive stages in making an SiC grid indicator.
  • the starting material to prepare a single crystal alpha-numeric indicator may be a platelet of green, nitrogen-doped SiC.
  • a typical platelet I is well formed as a hexagon on five sides; it is ground flat and polished with a metal-bonded diamond lap to achieve plane surfaces perpendicular to the c axis as shown in FIG. la; by way of example, the platelet may be as much as I5 millimeters across and about 0.5 millimeter thick after grinding and polishing. It may be desirable to cut the platelet to some standard size such as a 5X l O-mm. wafer as illustrated at 2 in FIG. lb and this may be done using a diamond saw.
  • FIG. 3 An alpha-numeric indicator 3 is illustrated in FIG. 3 wherein the pattern consists of rectangular framing lines 4, crosslines 5, and diagonal lines 6. Lines or V-grooves are cut or scribed into the face of the wafer by cementing it to a suitable support 7 and running a diamond saw across the upper face to create the pattern, as shown in FIG. 2.
  • the diamond saw may consist of a phosphor bronze disc 8 having a thin knife edge impregnated with diamond dust.
  • the width of the luminous lines may be-increased by making the cuts deeper and this also increases the visibility of the indicator, but-of course the cuts or grooves cannot exceed in depth the thickness of the wafer. Where a fine line indicating device is desired or where a grid pattern of many closely spaced dots is desired, the depth of the cuts may be reduced and this permits the lines to be placed closer together.
  • P type dopants preferably boron and aluminum
  • P type dopants are diffused into it. This may be done by placing the wafer within a doublewalled graphite crucible of which the outer vessel wall consists of dense graphite while the inner vessel wall is made of porous graphite or carbon.
  • the wafer is placed within the inner vessel and a protective charge of silicon and carbon with which are admixed the boron and aluminum dopants is located in the in tramural cavity between outer and inner walls.
  • suitable proportions for the protective charge are silicon and carbon in equal molar proportions plus 0.] atom percent Al and 0.1 mole percent H
  • the crucible is placed within a carbon tube furnace which is located within a vacuum chamber.
  • each half of a framing, cross and diagonal line of the pattern must be separately controlla ble to form all thecharacters desired.
  • a dot of silicon carbide paint consisting of fine grit SiC dispersed in mineral oil is applied to the midpoint and to the ends of each of the lines or V-cuts, as indicated by stippling at 13 in FIGS.
  • the wafer is then placed on a graphite resistance heater strip in a bell jar which is evacuated. The heater strip is heated by passing current through it to approximately 500 C. for 10 minutes to eliminate the oil, leaving only the SiC fine grit in place as a mask.
  • Individual connections to each P-type groove or line segment may be made by attaching wires IS to the metallized contact layer within the groove.
  • the wires may be attached by soldering or by thermocompression bonding when fine gold wires are used.
  • An ohmic contact is also made to the N-type material using suitable N-type contacting material such as silicon-phosphorus or gold-tantalum alloy.
  • suitable N-type contacting material such as silicon-phosphorus or gold-tantalum alloy.
  • the N-type material has good conductivity and a single small area contact to it suffices to which a wire may be attached, as indicated at 16 in FIG. 5.
  • the line segments Upon applying a few volts in the forward direction across the contacts (positive to P-side and negative to N-side), the line segments light up and are seen by looking down upon them from the opposite side through the thickness of the wafer, as in FIG. 6.
  • the letters and numbers which can be formed by selective energization of the segments can readily be seen in a normally illuminated room.
  • displays of various colors can be obtained, for instance green, yellow, orange and red.
  • FIGS. 7a to d illustrate successive stages in making a solidstate indicator consisting of a grid of closely spaced dots or luminous spots subject to individual control.
  • an N-type silicon carbide wafer 22 having relatively shallow closely spaced lines or V-grooves 23 cut or scribed in the top face.
  • the scribed wafer is next subject to diffusion of P-type dopants creating top and bottom P-type layers 24,25, and thereafter to vacuum evaporation of copper and silver to provide a contact layer 26 on the top face, as shown in FIG. 7b.
  • the top face is next cross grooved by cuts 27 running at right angles to the original V-cuts, as shown in FIG. 7c.
  • the wafer is then flat ground on the top face to remove both metallizing and P-type layers except within the grooves, and is also ground on the bottom face to remove the P-type layer, as shown in FIG. 7d.
  • Each groove is broken up into isolated segments, each short segment being a small P-type area or clot backed up by a metallizing layer of copper and silver. Individual connections to each P-type dot may now be made,
  • a contactor with conductors spatially arranged to contact the metallized segments of the wafer, or altematively by thermocompression bonding fine gold wires to the metallized dots.
  • a luminous pattern is created which is seen by looking at the dots through the thickness of the N-type material.
  • moving patterns may be created to convey infonnation.
  • a single-crystal display device comprising a wafer of N- type silicon carbide, grooves scribed in a face of the wafer forming line segments adapted to create intelligence-conveying patterns, P-type dopant difi'used into the wafer from the groove surfaces and forming P-type material along the grooves, contact metal deposited in said grooves and attached to the P-type material, a connection to exposed N-type material and individual connections to the contact metal attached to the P-type material within line segments.
  • a display device as in claim 1 wherein the contact metal deposited in the grooves comprises copper and silver.
  • the method of making a single-crystal display device which comprises obtaining a wafer of N-type silicon carbide, scribing one face of the wafer with grooves forming lines disposed to create intelligence-conveying patterns, diffusing a P-type dopant into said wafer, said grooves penetrating into said wafer a depth exceeding the diffusion depth of said P-type dopant, vacuum evaporating contact metal onto said P-type material, removing the contact metal and the P-type material from the face of the wafer except within the scribed grooves, and making a connection to the exposed N-type material and individual connections to the metal contacting the P-type material within the grooves.
  • V a a:

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Abstract

The display device is a wafer of N-type silicon carbide having lines or segments of lines scribed into one face in a selected design such as an alpha-numeric or a grid of closely spaced dots. After scribing, the wafer is diffused with P-type dopants such as boron and aluminum. Contact to the P-type material within the scribed lines is made by vacuum evaporation of copper-silver. The wafer faces are then lapped to remove the metallizing and P-type layer except within the scribed lines. A connection is then made to the N-type material, and individual connections to each P-type scribed-line segment. By selective energization of line segments, various luminous letters, numerals or characters may be formed which are seen through the N-type material.

Description

United States Patent Addamiano et al.
[151 3,636,397 51 Jan. 18,1972
[72] Inventors: Arrigo Addamiano, Willoughby; Ronald J.
Perusek, Chardon, both of Ohio [73] Assignee: General Electric Company [22] Filed: Apr. 10, 1969 21 Appl. No.: 815,047
Primary Examiner-John Kominski Assistant ExaminerDavid OReilly Attomey-Emest W. Legree, Henry P. Truesdell, Frank L, Neuhauser, Oscar B. Waddell and Melvin M. Goldenberg [57] ABSTRACT The display device is a wafer of N-type silicon carbide having lines or segments of lines scribed into one face in a selected design such as an alpha-numeric or a grid of closely spaced dots. After scribing, the wafer is diffused with P-type dopants such as boron and aluminum. Contact to the P-type material within the scribed lines is made by vacuum evaporation of copper-silver. The wafer faces are then lapped to remove the metallizing and P-type layer except within the scribed lines. A connection is then made to the N-type material, and individual connections to each P-type scribed-line segment. By selective energization of line segments, various luminous letters, numerals or characters may be formed which are seen through the N-type material.
8 Claims, 1 1 Drawing Figures PATENTEU JAN] 8872 31636.39.
smzu 1 er 2 Figgla. Fi gb lnven tors'. Ar'r'i cp o Addamiano RonaLd J. Perusek by JWW V Their A t torneg PATENTEnJAmnsn 3,636,397
sum ear 2 WWI/114W? ITWVTW tOTSI Arrigo Addamiano Ronatd J. Perusek SINGLE-CRYSTAL SILICON CARBIDE DISPLAY DEVICE CROSS-REFERENCES TO RELATED APPLICATIONS Copending application Ser. No. 732,442, filed May 27, 1968 by Arrigo Addamiano, entitled Formation of Junctions in Silicon Carbide by Selective Diffusion of Dopants and similarly assigned.
Copending application Ser. No. 685,447, filed Nov. 24, I967, now U.S. Pat. No. 3,458,779, by John M. Blank and Ralph M. Potter, entitled Silicon Carbide Light-Emitting Diodes" and similarly assigned.
BACKGROUND OF THE INVENTION The invention relates to solid-state subminiature display apparatus utilizing light-emitting junctions in silicon carbide. Light-emitting diodes or solid-state lamps of silicon carbide comprise a junction between n-type material which may be nitrogen doped and p-type material which may be boron and/or aluminum doped. When the device is suitably energized by the application of a forward potential across the junction, light is generated by the recombination of charge carriers in close proximity to the junction. In commercially available solid-state indicator lamps, a crystal chip containing a PN- junction is mounted P-side down on a header and light is emitted through the N-type top side which is contacted by a fine wire.
Solid-state visual display apparatus may be used for displaying symbols including alphabet letters, numerals and symbols of various kinds. Such apparatus is particularly useful in highspeed photographic recording because the response is sub stantially instantaneous. In copending application No. 732,442, filed May 27, 1968 by one of us (Arrigo Addamiano), entitled Formation of Junctions in Silicon Carbide by SelectiveDiffusion of Dopants," a method of creating lighting patterns in a single crystal of silicon carbide is disclosed which comprises diffusion of dopants into selected zones of the crystal. At the same time diffusion of dopants into other zones is prevented by covering or shielding such other zones by a refractory nonporous material, suitably fragments of silicon carbide crystals.
Among the objects of the invention are to provide improved solid-state display apparatus in which the selected designs are clearer and more legible and wherein more information may be conveyed within a given size, and to provide an improved process and technique for creating selected lighting designs in a silicon carbide wafer.
SUMMARY OF THE INVENTION The invention provides a solid-state display device consisting of a wafer of N-type silicon carbide having lines or segments of lines scribed into one face and forming a selected design such as an alpha-numeric or a grid of closely spaced dots. The lines are shallow grooves or V-cuts which may be made by a diamond saw. After scribing, the wafer is diffused with P-type dopants such as boron and aluminum. Contact to the P-type material within the grooves is made by vacuum evaporation of suitable metals such as copper and silver. In order to have individual lighting control of the various grooves or portions of grooves, masking of portions is done prior to the metallizing by vacuum evaporation. An alternative technique suitable for making a grid of closely spaced dots is to cross groove after metallizing. The wafer faces are then lapped to remove the metallizing and P-type layer except in the grooves or V-cuts. Individual connections to each P-type groove segment are then made and a single connection is also made to the N'type material. The luminous design is seen by looking at the grooves through the N-type wafer.
DESCRIPTION OF DRAWING FIG. la shows a silicon carbide crystal ground flat and FIG. lb shows a rectangular wafer cut therefrom.
FIG. 2 illustrates a diamond saw scribing a line into a wafer.
FIG. 3 shows a silicon carbide wafer having an alpha-numeric scribed into one face.
FIG. 4 is a cross section through a scribed line on a wafer after P-type diffusion and metal deposition.
FIG. 5 shows the same cross section as FIG. 4 after lapping and attachment of a wire lead.
FIG. 6 is a pictorial view of an alpha-numeric SiC indicator.
FIGS. 70, b, c and d show successive stages in making an SiC grid indicator.
DETAILED DESCRIPTION The starting material to prepare a single crystal alpha-numeric indicator may be a platelet of green, nitrogen-doped SiC. A typical platelet I is well formed as a hexagon on five sides; it is ground flat and polished with a metal-bonded diamond lap to achieve plane surfaces perpendicular to the c axis as shown in FIG. la; by way of example, the platelet may be as much as I5 millimeters across and about 0.5 millimeter thick after grinding and polishing. It may be desirable to cut the platelet to some standard size such as a 5X l O-mm. wafer as illustrated at 2 in FIG. lb and this may be done using a diamond saw.
An alpha-numeric indicator 3 is illustrated in FIG. 3 wherein the pattern consists of rectangular framing lines 4, crosslines 5, and diagonal lines 6. Lines or V-grooves are cut or scribed into the face of the wafer by cementing it to a suitable support 7 and running a diamond saw across the upper face to create the pattern, as shown in FIG. 2. The diamond saw may consist of a phosphor bronze disc 8 having a thin knife edge impregnated with diamond dust. The width of the luminous lines may be-increased by making the cuts deeper and this also increases the visibility of the indicator, but-of course the cuts or grooves cannot exceed in depth the thickness of the wafer. Where a fine line indicating device is desired or where a grid pattern of many closely spaced dots is desired, the depth of the cuts may be reduced and this permits the lines to be placed closer together.
After the selected design has been scribed into the wafer, P type dopants, preferably boron and aluminum, are diffused into it. This may be done by placing the wafer within a doublewalled graphite crucible of which the outer vessel wall consists of dense graphite while the inner vessel wall is made of porous graphite or carbon. The wafer is placed within the inner vessel and a protective charge of silicon and carbon with which are admixed the boron and aluminum dopants is located in the in tramural cavity between outer and inner walls. By way of example, suitable proportions for the protective charge are silicon and carbon in equal molar proportions plus 0.] atom percent Al and 0.1 mole percent H The crucible is placed within a carbon tube furnace which is located within a vacuum chamber. Reference may be made to copending application Ser. No. 685,447, filed Nov. 24, 1967, now US. Pat. No. 3,458,779, by John M. Blank and Ralph M. Potter for more details regarding diffusion of dopants and suitable furnace equipment for so doing. Diffusion may take place at a temperature of about 2,000 C. and results in a P-type surface layer, from 0.1 to 10 microns thick depending upon diffusion time and temperature. P-type layers are formed on both faces of the wafer and extend into the SiC from the grooves; the layers are shown by stippling at I1 and 12 in FIG. 4.
In an alpha-numeric indicator, each half of a framing, cross and diagonal line of the pattern must be separately controlla ble to form all thecharacters desired. This requires that each half-line or segment be insulated and this may be accomplished by suitable masking. A dot of silicon carbide paint consisting of fine grit SiC dispersed in mineral oil is applied to the midpoint and to the ends of each of the lines or V-cuts, as indicated by stippling at 13 in FIGS. The wafer is then placed on a graphite resistance heater strip in a bell jar which is evacuated. The heater strip is heated by passing current through it to approximately 500 C. for 10 minutes to eliminate the oil, leaving only the SiC fine grit in place as a mask. Contact to the P-type side is now made by vacuum evaporation of suitable metals, for instance aluminum-silicon alloy, preferably close to the eutectic composition, or nickelchromium or copper and silver. The entire upper surface of the wafer carrying the pattern becomes metallized as shown at 14 in FIG. 4. Both faces of the wafer are then ground and polished to remove the metallizing and P-type layer from all areas except within the grooves. At this stage the SiC fine grit is also removed by the polishing and this results in a discontinuity in the metallizing within the grooves at the places where the dots of SiC grit were applied.
Individual connections to each P-type groove or line segment may be made by attaching wires IS to the metallized contact layer within the groove. The wires may be attached by soldering or by thermocompression bonding when fine gold wires are used. An ohmic contact is also made to the N-type material using suitable N-type contacting material such as silicon-phosphorus or gold-tantalum alloy. The N-type material has good conductivity and a single small area contact to it suffices to which a wire may be attached, as indicated at 16 in FIG. 5.
Upon applying a few volts in the forward direction across the contacts (positive to P-side and negative to N-side), the line segments light up and are seen by looking down upon them from the opposite side through the thickness of the wafer, as in FIG. 6. The letters and numbers which can be formed by selective energization of the segments can readily be seen in a normally illuminated room. By choosing different types of SiC crystals and different dopants, displays of various colors can be obtained, for instance green, yellow, orange and red.
FIGS. 7a to d illustrate successive stages in making a solidstate indicator consisting of a grid of closely spaced dots or luminous spots subject to individual control. Referring to FIG. 7a, there is shown an N-type silicon carbide wafer 22 having relatively shallow closely spaced lines or V-grooves 23 cut or scribed in the top face. The scribed wafer is next subject to diffusion of P-type dopants creating top and bottom P- type layers 24,25, and thereafter to vacuum evaporation of copper and silver to provide a contact layer 26 on the top face, as shown in FIG. 7b. The top face is next cross grooved by cuts 27 running at right angles to the original V-cuts, as shown in FIG. 7c. The wafer is then flat ground on the top face to remove both metallizing and P-type layers except within the grooves, and is also ground on the bottom face to remove the P-type layer, as shown in FIG. 7d. This restores the bottom face to N- type and leaves the P-type material in the groove segments only on the top face. Each groove is broken up into isolated segments, each short segment being a small P-type area or clot backed up by a metallizing layer of copper and silver. Individual connections to each P-type dot may now be made,
either by using a contactor with conductors spatially arranged to contact the metallized segments of the wafer, or altematively by thermocompression bonding fine gold wires to the metallized dots. Upon energization, a luminous pattern is created which is seen by looking at the dots through the thickness of the N-type material. By selective energization of the various dots, moving patterns may be created to convey infonnation.
What we claim as new and desire to secure by Letters Patent of the United States is:
l. A single-crystal display device comprising a wafer of N- type silicon carbide, grooves scribed in a face of the wafer forming line segments adapted to create intelligence-conveying patterns, P-type dopant difi'used into the wafer from the groove surfaces and forming P-type material along the grooves, contact metal deposited in said grooves and attached to the P-type material, a connection to exposed N-type material and individual connections to the contact metal attached to the P-type material within line segments.
2. A display device as in claim 1 wherein the grooves are disposed as framing, cross and diagonal lines to form an alphanumeric indicator. I
3. A display device as in claim 1 wherein the grooves are disposed in parallel and closely spaced, and cross grooves break up the original grooves into segments to form a grid indicator of closely spaced luminous spots.
4. A display device as in claim 1 wherein the P-type dopant comprises boron and aluminum.
5. A display device as in claim 1 wherein the contact metal deposited in the grooves comprises copper and silver.
6. The method of making a single-crystal display device which comprises obtaining a wafer of N-type silicon carbide, scribing one face of the wafer with grooves forming lines disposed to create intelligence-conveying patterns, diffusing a P-type dopant into said wafer, said grooves penetrating into said wafer a depth exceeding the diffusion depth of said P-type dopant, vacuum evaporating contact metal onto said P-type material, removing the contact metal and the P-type material from the face of the wafer except within the scribed grooves, and making a connection to the exposed N-type material and individual connections to the metal contacting the P-type material within the grooves.
7. The method of claim 6 wherein portions of the grooves are masked prior to dopant diffusion and contact metal evaporation in order to have line segments formed by the unmasked portions, and individual connections are made to the line segments.
8. The method of claim 6 wherein said one face is scribed with cross grooves after dopant diffusion and contact metal evaporation in order to break up the original grooves into segments, and individual connections are made to the groove segments. 7
V a: a:

Claims (7)

  1. 2. A display device as in claim 1 wherein the grooves are disposed as framing, cross and diagonal lines to form an alpha-numeric indicator.
  2. 3. A display device as in claim 1 wherein the grooves are disposed in parallel and closely spaced, and cross grooves break up the original grooves into segments to form a grid indicator of closely spaced luminous spots.
  3. 4. A display device as in claim 1 wherein the P-type dopant comprises boron and aluminum.
  4. 5. A display device as in claim 1 wherein the contact metal deposited in the grooves comprises copper and silver.
  5. 6. The method of making a single-crystal display device which comprises obtaining a wafer of N-type silicon carbide, scribing one face of the wafer with grooves forming lines disposed to create intelligence-conveying patterns, diffusing a P-type dopant into said wafer, said grooves penetrating into said wafer a depth exceeding the diffusion depth of said P-type dopant, vacuum evaporating contact metal onto said P-type material, removing the contact metal and the P-type material from the face of the wafer except within the scribed grooves, and making a connection to the exposed N-type material and individual connections to the metal contacting the P-type material within the grooves.
  6. 7. The method of claim 6 wherein portions of the grooves are masked prior to dopant diffusion and contact metal evaporation in order to have line segments formed by the unmasked portions, and individual connections are made to the line segments.
  7. 8. The method of claim 6 wherein said one face is scribed with cross grooves after dopant diffusion and contact metal evaporation in order to break up the original grooves into segments, and individual connections are made to the groove segments.
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3886581A (en) * 1972-12-28 1975-05-27 Tokyo Shibaura Electric Co Display device using light-emitting semiconductor elements
US3942065A (en) * 1974-11-11 1976-03-02 Motorola, Inc. Monolithic, milticolor, light emitting diode display device
US4217689A (en) * 1976-09-14 1980-08-19 Mitsubishi Denki Kabushiki Kaisha Process for preparing semiconductor devices
US5006914A (en) * 1988-12-02 1991-04-09 Advanced Technology Materials, Inc. Single crystal semiconductor substrate articles and semiconductor devices comprising same
US5030583A (en) * 1988-12-02 1991-07-09 Advanced Technolgy Materials, Inc. Method of making single crystal semiconductor substrate articles and semiconductor device
US5726463A (en) * 1992-08-07 1998-03-10 General Electric Company Silicon carbide MOSFET having self-aligned gate structure
US5914499A (en) * 1995-01-18 1999-06-22 Abb Research Ltd. High voltage silicon carbide semiconductor device with bended edge
US6417524B1 (en) * 1996-06-05 2002-07-09 Princeton Lightwave Inc. Light emitting semiconductor device
US20030155859A1 (en) * 1999-03-19 2003-08-21 Masayuki Nakamoto Method of manufacturing field emission device and display apparatus
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Families Citing this family (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3510732A (en) * 1968-04-22 1970-05-05 Gen Electric Solid state lamp having a lens with rhodamine or fluorescent material dispersed therein
US3562609A (en) * 1968-06-04 1971-02-09 Gen Electric Solid state lamp utilizing emission from edge of a p-n junction
US3565703A (en) * 1969-07-09 1971-02-23 Norton Research Corp Silicon carbide junction diode
US3611064A (en) * 1969-07-14 1971-10-05 Gen Electric Ohmic contact to n-type silicon carbide, comprising nickel-titanium-gold
US3805347A (en) * 1969-12-29 1974-04-23 Gen Electric Solid state lamp construction
US3638026A (en) * 1970-06-29 1972-01-25 Honeywell Inc Or photovoltaic device
US3715636A (en) * 1972-01-03 1973-02-06 Gen Electric Silicon carbide lamp mounted on a ceramic of poor thermal conductivity
US3832668A (en) * 1972-03-31 1974-08-27 Westinghouse Electric Corp Silicon carbide junction thermistor
US3798084A (en) * 1972-08-11 1974-03-19 Ibm Simultaneous diffusion processing
FR2210073A1 (en) * 1972-12-13 1974-07-05 Maslakovets Jury Semiconductor light source - with near linear luminance/current relationship, suitable for low temp operation
JPS49113577A (en) * 1973-02-08 1974-10-30
US3986193A (en) * 1973-02-08 1976-10-12 Jury Alexandrovich Vodakov Semiconductor SiCl light source and a method of manufacturing same
US3836759A (en) * 1973-08-20 1974-09-17 S Silverman Safety light circuit
US3852591A (en) * 1973-10-19 1974-12-03 Bell Telephone Labor Inc Graded bandgap semiconductor photodetector for equalization of optical fiber material delay distortion
US3956032A (en) * 1974-09-24 1976-05-11 The United States Of America As Represented By The United States National Aeronautics And Space Administration Process for fabricating SiC semiconductor devices
US4176294A (en) * 1975-10-03 1979-11-27 Westinghouse Electric Corp. Method and device for efficiently generating white light with good rendition of illuminated objects
US4267559A (en) * 1979-09-24 1981-05-12 Bell Telephone Laboratories, Incorporated Low thermal impedance light-emitting diode package
US4556436A (en) * 1984-08-22 1985-12-03 The United States Of America As Represented By The Secretary Of The Navy Method of preparing single crystalline cubic silicon carbide layers
US5027168A (en) * 1988-12-14 1991-06-25 Cree Research, Inc. Blue light emitting diode formed in silicon carbide
US4918497A (en) * 1988-12-14 1990-04-17 Cree Research, Inc. Blue light emitting diode formed in silicon carbide
JP4629809B2 (en) * 1996-03-27 2011-02-09 クリー，インコーポレイテッド Method of manufacturing a semiconductor device having a SiC semiconductor layer
US6204160B1 (en) 1999-02-22 2001-03-20 The United States Of America As Represented By The Secretary Of The Navy Method for making electrical contacts and junctions in silicon carbide
US20070188717A1 (en) * 2006-02-14 2007-08-16 Melcher Charles L Method for producing crystal elements having strategically oriented faces for enhancing performance
US20100252853A1 (en) * 2009-03-19 2010-10-07 Christy Alexander C Thermal Energy Dissipating Arrangement for a Light Emitting Diode
USD877707S1 (en) 2017-03-30 2020-03-10 Mitsubishi Electric Corporation Semiconductor package
CN217382611U (en) * 2022-06-01 2022-09-06 江西奥赛光电有限公司 Direct insertion type point control lamp and lamp string structure

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3236780A (en) * 1962-12-19 1966-02-22 Gen Electric Luminescent silicon carbide and preparation thereof
US3404304A (en) * 1964-04-30 1968-10-01 Texas Instruments Inc Semiconductor junction device for generating optical radiation
GB1052587A (en) * 1964-06-30
US3377210A (en) * 1965-03-25 1968-04-09 Norton Co Process of forming silicon carbide diode by growing separate p and n layers together
US3389022A (en) * 1965-09-17 1968-06-18 United Aircraft Corp Method for producing silicon carbide layers on silicon substrates

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* Cited by examiner, † Cited by third party
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US3886581A (en) * 1972-12-28 1975-05-27 Tokyo Shibaura Electric Co Display device using light-emitting semiconductor elements
US3942065A (en) * 1974-11-11 1976-03-02 Motorola, Inc. Monolithic, milticolor, light emitting diode display device
US4217689A (en) * 1976-09-14 1980-08-19 Mitsubishi Denki Kabushiki Kaisha Process for preparing semiconductor devices
US5006914A (en) * 1988-12-02 1991-04-09 Advanced Technology Materials, Inc. Single crystal semiconductor substrate articles and semiconductor devices comprising same
US5030583A (en) * 1988-12-02 1991-07-09 Advanced Technolgy Materials, Inc. Method of making single crystal semiconductor substrate articles and semiconductor device
US5726463A (en) * 1992-08-07 1998-03-10 General Electric Company Silicon carbide MOSFET having self-aligned gate structure
US5914499A (en) * 1995-01-18 1999-06-22 Abb Research Ltd. High voltage silicon carbide semiconductor device with bended edge
US6417524B1 (en) * 1996-06-05 2002-07-09 Princeton Lightwave Inc. Light emitting semiconductor device
US20030155859A1 (en) * 1999-03-19 2003-08-21 Masayuki Nakamoto Method of manufacturing field emission device and display apparatus
US20060178076A1 (en) * 1999-03-19 2006-08-10 Masayuki Nakamoto Method of manufacturing field emission device and display apparatus
US7175495B2 (en) * 1999-03-19 2007-02-13 Kabushiki Kaisha Toshiba Method of manufacturing field emission device and display apparatus
CN111771259A (en) * 2018-02-28 2020-10-13 Abb电网瑞士股份公司 Method for co-injecting p-type doped silicon carbide through Al/Be
CN111771259B (en) * 2018-02-28 2021-07-02 Abb电网瑞士股份公司 Method for co-injecting p-type doped silicon carbide through Al/Be
US11211248B2 (en) 2018-02-28 2021-12-28 Abb Power Grids Switzerland Ag SiC electronic device fabricated by Al/Be co-implantation

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DE1810472A1 (en) 1970-03-26

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