US3572672A - Vacuum evaporation apparatus - Google Patents

Vacuum evaporation apparatus Download PDF

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Publication number
US3572672A
US3572672A US778130A US3572672DA US3572672A US 3572672 A US3572672 A US 3572672A US 778130 A US778130 A US 778130A US 3572672D A US3572672D A US 3572672DA US 3572672 A US3572672 A US 3572672A
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crucible
vacuum evaporation
upper portion
heat shield
heat
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US778130A
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Abraham Harel
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RCA Corp
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RCA Corp
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24—Vacuum evaporation
    • C23C14/243—Crucibles for source material

Definitions

  • a crucible for holding a quantity of material to be evaporated in a vacuum evaporation system includes an elongated tubular upper portion and a heat shield to confine heat to the lower portion of the crucible so that the upper portion remains cooler than the lower portion. This prevents overflowing and serves to collimate the evaporant.
  • This invention relates to vacuum evaporation apparatus and, more particularly, to apparatus including a crucible for holding a relatively large quantity of a substance to be evaporated so that prolonged evaporation is made possible.
  • Vacuum evaporation is widely used in the electronics industry, for example, for the application of relatively thin coatings of materials such as aluminum to surfaces of electronic components. Evaporated aluminum leads and contacts for semiconductor devices are common.
  • the manufacture of television picture tubes includes the application of a coating of aluminum to the surface of the envelope of the tube.
  • the present apparatus includes a crucible having an elongated tubular upper portion with an open end through whichi lb ⁇ THE DRAWINGS
  • the single FIGURE is a vertical cross-sectional view of the present apparatus.
  • the apparatus 10 includes a tubular housing 12, which is made of a refractory material, supported on a suitable thermal insulator 13.
  • the tubular housing 12 which is made of a refractory material, supported on a suitable thermal insulator 13.
  • housing 12 has a closed lower end 14 and a top surface 15 defining an open upper end for receiving the other elements of the apparatus 10.
  • a crucible 16 made of a material which is electrically and thermally insulating and chemically inert, such as pyrolytic boron nitride, is supported in the open upper end of the housing 12.
  • the crucible 16 has an elongated tubular upper portion 18, a conical lower portion 20 defining a closed end, and a threaded midportion 21.
  • a heat shield 22 having the shape of an annular disc with a concentric, internally threaded opening is assembled on the midportion 21 of the crucible 16.
  • An annular stop 24 on the crucible 16 serves to define the position of the heat shield 22 thereon.
  • the diameter of the heat shield 22 is such that the shield may rest on the surface 15 of the housing 12 to support the crucible 16 thereon and to define, with the housing 12, a chamber for confining heat to the vicinity of the lower end portion 20 of the crucible 16.
  • a resistance heating element 26, in conical coil form, is disposed tightly around the lower conical end portion 20 of the crucible 16.
  • the heating element 26 is made of resilient tungsten or molybdenum wire.
  • the size of the element 26 should be such that it is stretched when it is in place on the crucible 16 with its uppermost turn disposed in the lower thread of the midportion 21 of the crucible.
  • Input and output conductors 28 and 30, respectively, extend from the heating element 26 to the outside of the housing 12 through suitable slots 32 and 34 in the walls thereof.
  • a power source represented by a battery 36, may be connected to the leads 28 and 30 to produce heat in the heating element 26 to melt the material in the crucible 16.
  • a quantity of material such as aluminum is placed in the crucible l6 and the .apparatus 10 is then placed in a vacuum system, not shown, with the open end of the crucible 16 directed upward toward the article to be coated. Low-pressure conditions are established and current is then passed through the heating element 26 to melt the material in the crucible 16 and form a bath of molten liquid, 38.
  • the present apparatus permits the use of crucible materials which are chemically inert to the material being evaporated even though they are wetted thereby.
  • the result of wetting is that the material creeps up the walls of the crucible 16 by capillary action. This is indicated in the drawing by the quantity of material 40 which appears as a coating on the wall of the crucible 16.
  • the heat shield 22 confines heat from the coil 26 to the lower portion 20 of the crucible 16. Heat may flow by conduction through the walls of the midportion 21 of the crucible 16 to the upper portion 18 thereof, but this heat is minimized by the thinness and relatively low thermal conductivity of the crucible wall. Moreover, the relatively large surface area of the tubular portion 18 of the crucible 16 provides a large radiating surface for the dissipation of any heat which does reach the upper portion 18. Consequently, the upper portion 18 remains relatively cool.
  • Molten material 40 rising up the interior wall of the upper portion 18 cools and solidifies upon encountering the relatively cooler material thereof.
  • a dam, 41, of solidified material is thereby established which prevents any further flow of material up the wall of the crucible. Consequently, the material cannot overflow from the crucible.
  • the elongation of the tubular upper portion 18 also serves to collimate the evaporation of the material 38.
  • the mean free path of atoms or molecules in the vacuum is relatively long so that material proceeds in straight lines from the molten zone.
  • a crucible for holding a substance to be evaporated, said crucible having an elongated tubular upper portion with an open end and a lower portion with a closed end and being of a material which is wetted by said substance;
  • heat shield means thermally coupled to said crucible for confining heat to said lower portion of said crucible and for maintaining said upper portion of said crucible at a substantially lower temperature than said lower portion of said crucible, whereby overflow of said substance from said crucible is prevented.

Abstract

A crucible for holding a quantity of material to be evaporated in a vacuum evaporation system includes an elongated tubular upper portion and a heat shield to confine heat to the lower portion of the crucible so that the upper portion remains cooler than the lower portion. This prevents overflowing and serves to collimate the evaporant.

Description

United States Patent Inventor Abraham Harel [56] References Cited Trenton, NJ. UNITED STATES PATENTS APPLNO- 778,130 2,643,201 6/1953 Chadseyetal 117/107 Flled Fwy-22,1968 2,665,223 1/1954 0611916161.... 75/68 Pmmed Mar-30,1971, 2,772,318 11/1956 Holland 117/107 Asslgnee RCACMPMM" 3,329,524 7/1967 Smith 117/107 FOREIGN PATENTS 742,066 1955 GreatBritain 118/48- VACUUM EVAPORATION APPARATUS 4 Claims, 1 Drawing Fig.
US. Cl
Int. Cl. Field of Search (V); 75/65, 68; 1 17/107; 118/48, 49,49.1,49.5; 263/(lnquired) Primary Examiner-Gerald A. Dost Att0rneyGlenn H. Bruestle ABSTRACT: A crucible for holding a quantity of material to be evaporated in a vacuum evaporation system includes an elongated tubular upper portion and a heat shield to confine heat to the lower portion of the crucible so that the upper portion remains cooler than the lower portion. This prevents overflowing and serves to collimate the evaporant.
Patented March 30, 1971 N YEN TOR /4! e4//4M #4151 VACUUM EVAPORATION APPARATUS BACKGROUND OF THE INVENTION This invention relates to vacuum evaporation apparatus and, more particularly, to apparatus including a crucible for holding a relatively large quantity of a substance to be evaporated so that prolonged evaporation is made possible.
Vacuum evaporation is widely used in the electronics industry, for example, for the application of relatively thin coatings of materials such as aluminum to surfaces of electronic components. Evaporated aluminum leads and contacts for semiconductor devices are common. The manufacture of television picture tubes includes the application of a coating of aluminum to the surface of the envelope of the tube.
Other materials including semiconductors, insulators, and metals are also applied by the process of vacuum evaporation. For some of these materials, it has been common practice to place smallbodi es thereof directly on a coiled filament. This method, however, does not permit prolonged evaporation or relatively large quantities of material.
The evaporation of aluminum, in particular, over relatively long periods of time poses several "problems. Molten aluminum tends to attack the usualcrucible materials, such as alumina. Molten aluminum wets many crucible materials and capillary attraction causes the aluminum to creep up the sides of the crucible and overflow. Flash evaporation of small aluminum pellets [dropped into a hot crucible requires an n" elaborate pellet feeding mechanism.
SUMMARY OF THE INVENTION The present apparatus includes a crucible having an elongated tubular upper portion with an open end through whichi lb} THE DRAWINGS The single FIGURE; is a vertical cross-sectional view of the present apparatus. 1
THE/PREFERREID EMBODIMENT The presenttihovel vacuum, evaporation apparatus is illustrated generally at in the drawing. As shown, the apparatus 10 includes a tubular housing 12, which is made of a refractory material, supported on a suitable thermal insulator 13. The
housing 12 has a closed lower end 14 and a top surface 15 defining an open upper end for receiving the other elements of the apparatus 10.
A crucible 16, made of a material which is electrically and thermally insulating and chemically inert, such as pyrolytic boron nitride, is supported in the open upper end of the housing 12. The crucible 16 has an elongated tubular upper portion 18, a conical lower portion 20 defining a closed end, and a threaded midportion 21. A heat shield 22 having the shape of an annular disc with a concentric, internally threaded opening is assembled on the midportion 21 of the crucible 16. An annular stop 24 on the crucible 16 serves to define the position of the heat shield 22 thereon. The diameter of the heat shield 22 is such that the shield may rest on the surface 15 of the housing 12 to support the crucible 16 thereon and to define, with the housing 12, a chamber for confining heat to the vicinity of the lower end portion 20 of the crucible 16.
A resistance heating element 26, in conical coil form, is disposed tightly around the lower conical end portion 20 of the crucible 16. Typically, the heating element 26 is made of resilient tungsten or molybdenum wire. The size of the element 26 should be such that it is stretched when it is in place on the crucible 16 with its uppermost turn disposed in the lower thread of the midportion 21 of the crucible. The
resiliency of the heating element 26 then holds it in tight, thermally efficient contact with the lower end portion 20 of the crucible 16.
Input and output conductors 28 and 30, respectively, extend from the heating element 26 to the outside of the housing 12 through suitable slots 32 and 34 in the walls thereof. A power source, represented by a battery 36, may be connected to the leads 28 and 30 to produce heat in the heating element 26 to melt the material in the crucible 16.
In the use of the present apparatus, a quantity of material such as aluminum is placed in the crucible l6 and the .apparatus 10 is then placed in a vacuum system, not shown, with the open end of the crucible 16 directed upward toward the article to be coated. Low-pressure conditions are established and current is then passed through the heating element 26 to melt the material in the crucible 16 and form a bath of molten liquid, 38.
The present apparatus permits the use of crucible materials which are chemically inert to the material being evaporated even though they are wetted thereby. The result of wetting is that the material creeps up the walls of the crucible 16 by capillary action. This is indicated in the drawing by the quantity of material 40 which appears as a coating on the wall of the crucible 16.
The heat shield 22 confines heat from the coil 26 to the lower portion 20 of the crucible 16. Heat may flow by conduction through the walls of the midportion 21 of the crucible 16 to the upper portion 18 thereof, but this heat is minimized by the thinness and relatively low thermal conductivity of the crucible wall. Moreover, the relatively large surface area of the tubular portion 18 of the crucible 16 provides a large radiating surface for the dissipation of any heat which does reach the upper portion 18. Consequently, the upper portion 18 remains relatively cool.
Molten material 40 rising up the interior wall of the upper portion 18 cools and solidifies upon encountering the relatively cooler material thereof. A dam, 41, of solidified material is thereby established which prevents any further flow of material up the wall of the crucible. Consequently, the material cannot overflow from the crucible.
The elongation of the tubular upper portion 18 also serves to collimate the evaporation of the material 38. As is generally known in the vacuum evaporation art, the mean free path of atoms or molecules in the vacuum is relatively long so that material proceeds in straight lines from the molten zone. In
Moreover, material is not reflected from the walls of the chamber.
Iclaim:
1. In a vacuum evaporation apparatus:
a crucible for holding a substance to be evaporated, said crucible having an elongated tubular upper portion with an open end and a lower portion with a closed end and being of a material which is wetted by said substance;
means adjacent to said lower portion of said crucible for heating said substance; and
heat shield means thermally coupled to said crucible for confining heat to said lower portion of said crucible and for maintaining said upper portion of said crucible at a substantially lower temperature than said lower portion of said crucible, whereby overflow of said substance from said crucible is prevented.
2. Apparatus as defined in claim 1 wherein said crucible is formed of boron nitride.
3. Apparatus as defined in claim 1 wherein said crucible has an externally threaded portion thereon and said heat shield means comprises a disc having a threaded opening therein adapted to be engaged with said threaded portion of said

Claims (3)

  1. 2. Apparatus as defined in claim 1 wherein said crucible is formed of boron nitride.
  2. 3. Apparatus as defined in claim 1 wherein said crucible has an externally threaded portion thereon and said heat shield means comprises a disc having a threaded opening therein adapted to be engaged with said threaded portion of said crucible.
  3. 4. Apparatus as defined in claim 1 wherein said heat shield means comprises a radially extending disc surrounding said crucible and wherein said tubular upper portion extends a substantial distance above said heat shield.
US778130A 1968-11-22 1968-11-22 Vacuum evaporation apparatus Expired - Lifetime US3572672A (en)

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3664295A (en) * 1970-11-02 1972-05-23 Gte Sylvania Inc Means for achieving a controlled gradient density coating on a light attenuation medium
US4125086A (en) * 1977-01-06 1978-11-14 The United States Of America As Represented By The Secretary Of The Army Nozzle beam type metal vapor source
US4530854A (en) * 1982-09-23 1985-07-23 Honeywell Inc. Focusing device for external flashing of getters
FR2582319A1 (en) * 1985-05-22 1986-11-28 Barbier Benard & Turenne Plant for nickel deposition by vacuum evaporation, especially for the preparation of neutron guides
FR2584100A1 (en) * 1984-06-12 1987-01-02 Ki Polt I EVAPORATOR FOR THE VACUUM EVAPORATION OF THIN FILM DEPOSITS
DE3590269C2 (en) * 1984-06-12 1988-01-14 Ki Politekhn I Im 50 Letijavel Evaporator for vacuum deposition of films - has means for forming directed flow of deposition material vapour from crucible up to substrate
WO1989012117A1 (en) * 1988-05-31 1989-12-14 Kievsky Politekhnichesky Institut Imeni 50-Letia V Device for vacuum deposition of films
US5253266A (en) * 1992-07-20 1993-10-12 Intevac, Inc. MBE effusion source with asymmetrical heaters
US5558720A (en) * 1996-01-11 1996-09-24 Thermacore, Inc. Rapid response vapor source
US20030017714A1 (en) * 2001-07-12 2003-01-23 Hitachi Kokusai Electric Inc. Substrate processing apparatus and method for manufacturing semiconductor device
US20100159132A1 (en) * 2008-12-18 2010-06-24 Veeco Instruments, Inc. Linear Deposition Source
US20100282167A1 (en) * 2008-12-18 2010-11-11 Veeco Instruments Inc. Linear Deposition Source
US20100285218A1 (en) * 2008-12-18 2010-11-11 Veeco Instruments Inc. Linear Deposition Source
US20120285374A1 (en) * 2011-05-12 2012-11-15 Hon Hai Precision Industry Co., Ltd. Evaporation source with flame jetting unit and related evaporation deposition system
DE102014221561A1 (en) * 2014-10-23 2016-04-28 Beijing Apollo Ding Rong Solar Technology Co., Ltd. Apparatus for receiving evaporating material and method for producing a device
US20160208374A1 (en) * 2015-01-20 2016-07-21 Kennametal Inc. Imc evaporator boat-thermal insulation cartridge assembly
US10017848B2 (en) * 2016-10-11 2018-07-10 Au Optronics Corporation Crucible
US11821062B2 (en) 2019-04-29 2023-11-21 Kennametal Inc. Cemented carbide compositions and applications thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2643201A (en) * 1949-12-24 1953-06-23 Nat Res Corp Coating method and apparatus therefor
US2665223A (en) * 1949-12-31 1954-01-05 Nat Res Corp Process for depositing an aluminum film on a substrate by thermal vaporization
GB742066A (en) * 1953-02-09 1955-12-21 British Dielectric Res Ltd Improvements in the deposition of material evaporated in a vacuum
US2772318A (en) * 1952-12-31 1956-11-27 Holland Leslie Arthur Apparatus for vaporization of metals and metalloids
US3329524A (en) * 1963-06-12 1967-07-04 Temescal Metallurgical Corp Centrifugal-type vapor source

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2643201A (en) * 1949-12-24 1953-06-23 Nat Res Corp Coating method and apparatus therefor
US2665223A (en) * 1949-12-31 1954-01-05 Nat Res Corp Process for depositing an aluminum film on a substrate by thermal vaporization
US2772318A (en) * 1952-12-31 1956-11-27 Holland Leslie Arthur Apparatus for vaporization of metals and metalloids
GB742066A (en) * 1953-02-09 1955-12-21 British Dielectric Res Ltd Improvements in the deposition of material evaporated in a vacuum
US3329524A (en) * 1963-06-12 1967-07-04 Temescal Metallurgical Corp Centrifugal-type vapor source

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3664295A (en) * 1970-11-02 1972-05-23 Gte Sylvania Inc Means for achieving a controlled gradient density coating on a light attenuation medium
US4125086A (en) * 1977-01-06 1978-11-14 The United States Of America As Represented By The Secretary Of The Army Nozzle beam type metal vapor source
US4530854A (en) * 1982-09-23 1985-07-23 Honeywell Inc. Focusing device for external flashing of getters
FR2584100A1 (en) * 1984-06-12 1987-01-02 Ki Polt I EVAPORATOR FOR THE VACUUM EVAPORATION OF THIN FILM DEPOSITS
US4700660A (en) * 1984-06-12 1987-10-20 Kievsky Politekhnichesky Institut Evaporator for depositing films in a vacuum
DE3590269C2 (en) * 1984-06-12 1988-01-14 Ki Politekhn I Im 50 Letijavel Evaporator for vacuum deposition of films - has means for forming directed flow of deposition material vapour from crucible up to substrate
FR2582319A1 (en) * 1985-05-22 1986-11-28 Barbier Benard & Turenne Plant for nickel deposition by vacuum evaporation, especially for the preparation of neutron guides
WO1989012117A1 (en) * 1988-05-31 1989-12-14 Kievsky Politekhnichesky Institut Imeni 50-Letia V Device for vacuum deposition of films
US5016566A (en) * 1988-05-31 1991-05-21 Levchenko Georgy T Apparatus for forming films by evaporation in vacuum
US5253266A (en) * 1992-07-20 1993-10-12 Intevac, Inc. MBE effusion source with asymmetrical heaters
US5558720A (en) * 1996-01-11 1996-09-24 Thermacore, Inc. Rapid response vapor source
US20030017714A1 (en) * 2001-07-12 2003-01-23 Hitachi Kokusai Electric Inc. Substrate processing apparatus and method for manufacturing semiconductor device
US6923867B2 (en) * 2001-07-12 2005-08-02 Hitachi Kokusai Electric Inc. Substrate processing apparatus and method for manufacturing semiconductor device
US20100159132A1 (en) * 2008-12-18 2010-06-24 Veeco Instruments, Inc. Linear Deposition Source
US20100282167A1 (en) * 2008-12-18 2010-11-11 Veeco Instruments Inc. Linear Deposition Source
US20100285218A1 (en) * 2008-12-18 2010-11-11 Veeco Instruments Inc. Linear Deposition Source
US20120285374A1 (en) * 2011-05-12 2012-11-15 Hon Hai Precision Industry Co., Ltd. Evaporation source with flame jetting unit and related evaporation deposition system
DE102014221561A1 (en) * 2014-10-23 2016-04-28 Beijing Apollo Ding Rong Solar Technology Co., Ltd. Apparatus for receiving evaporating material and method for producing a device
US20160208374A1 (en) * 2015-01-20 2016-07-21 Kennametal Inc. Imc evaporator boat-thermal insulation cartridge assembly
CN105803402A (en) * 2015-01-20 2016-07-27 钴碳化钨硬质合金公司 IMC evaporator boat-thermal insulation cartridge assembly
US10184168B2 (en) * 2015-01-20 2019-01-22 Kennametal Inc. IMC evaporator boat-thermal insulation cartridge assembly
US10017848B2 (en) * 2016-10-11 2018-07-10 Au Optronics Corporation Crucible
US11821062B2 (en) 2019-04-29 2023-11-21 Kennametal Inc. Cemented carbide compositions and applications thereof

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