US3751293A - Method for reducing interdiffusion rates between thin film components - Google Patents
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- US3751293A US3751293A US00813421A US3751293DA US3751293A US 3751293 A US3751293 A US 3751293A US 00813421 A US00813421 A US 00813421A US 3751293D A US3751293D A US 3751293DA US 3751293 A US3751293 A US 3751293A
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- 238000000034 method Methods 0.000 title claims abstract description 33
- 239000010409 thin film Substances 0.000 title abstract description 24
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910052786 argon Inorganic materials 0.000 claims abstract description 9
- 239000007789 gas Substances 0.000 claims description 17
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 10
- 229910052737 gold Inorganic materials 0.000 claims description 8
- 239000010931 gold Substances 0.000 claims description 8
- 239000001307 helium Substances 0.000 claims description 6
- 229910052734 helium Inorganic materials 0.000 claims description 6
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 6
- 229910052709 silver Inorganic materials 0.000 claims description 6
- 239000004332 silver Substances 0.000 claims description 6
- 238000000151 deposition Methods 0.000 abstract description 11
- 239000010408 film Substances 0.000 abstract description 11
- 239000011261 inert gas Substances 0.000 abstract 1
- 229910052751 metal Inorganic materials 0.000 description 19
- 239000002184 metal Substances 0.000 description 19
- 238000007738 vacuum evaporation Methods 0.000 description 9
- 150000002739 metals Chemical class 0.000 description 7
- 239000000758 substrate Substances 0.000 description 7
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 7
- 229910052721 tungsten Inorganic materials 0.000 description 7
- 239000010937 tungsten Substances 0.000 description 7
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 6
- 230000008021 deposition Effects 0.000 description 6
- 238000001579 optical reflectometry Methods 0.000 description 6
- 239000002131 composite material Substances 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 5
- 238000001704 evaporation Methods 0.000 description 4
- 230000008020 evaporation Effects 0.000 description 4
- PQTCMBYFWMFIGM-UHFFFAOYSA-N gold silver Chemical compound [Ag].[Au] PQTCMBYFWMFIGM-UHFFFAOYSA-N 0.000 description 4
- 238000002310 reflectometry Methods 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000005304 joining Methods 0.000 description 2
- 229910052743 krypton Inorganic materials 0.000 description 2
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 239000002905 metal composite material Substances 0.000 description 2
- 229910052754 neon Inorganic materials 0.000 description 2
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 2
- 229910052704 radon Inorganic materials 0.000 description 2
- SYUHGPGVQRZVTB-UHFFFAOYSA-N radon atom Chemical compound [Rn] SYUHGPGVQRZVTB-UHFFFAOYSA-N 0.000 description 2
- 238000001771 vacuum deposition Methods 0.000 description 2
- 229910052724 xenon Inorganic materials 0.000 description 2
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 2
- XDLMVUHYZWKMMD-UHFFFAOYSA-N 3-trimethoxysilylpropyl 2-methylprop-2-enoate Chemical compound CO[Si](OC)(OC)CCCOC(=O)C(C)=C XDLMVUHYZWKMMD-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
-
- 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
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/14—Metallic material, boron or silicon
- C23C14/18—Metallic material, boron or silicon on other inorganic substrates
-
- 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
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N97/00—Electric solid-state thin-film or thick-film devices, not otherwise provided for
Definitions
- ABSTRACT 5 I E 3 S 4 22 A method for reducing interd1ffus1on rates between [58] Fie'ld 6 217 227 1 thin film conductive components.
- the method comprises vacuum depositing the conductive films at a par- [56] Refrences Cited tial pressure of 10-70 nicrons in the presence of an t UNITED STATES PATENTS met (e g Argon) 3,028,663 4/1962 lwersen et al l-l7/l07 5 Claims, 2 Drawing Figures PAIENIEUMIB Hm 1660 HRS H c. THEUERER MEMO P.A.
- TURNER B A TTORNEV METHOD FOR REDUCING INTERDIFFUSION RATES BETWEEN THIN FILM COMPONENTS
- This invention relates to a technique for reducing the interdiffusion rates of thin film components. More particularly, the present invention relates to a technique for reducing the interdiffusion rates between thin film conductive components wherein the components of interest are deposited by vacuum evaporation techniques in the presence of a non-reactive gas.
- the prior art difficulties encountered in connection with such thin film composites have been significantly lessened by a novel technique which causes a reduction in interdiffusion rates between the components of the composite.
- the inventive technique involves depositing thin film conducting composites by vacuum evaporation techniques in the presence of a suitable non-reactive gas. Studies have revealed that processing in the tile. scribed manner results in the reduction of the diffusivity of metals by segregating diffusion paths and impeding the movement of diffusants by incorporation of the gas of interest in grain boundaries and dislocation cores.
- FIG. 1 is a front elevational view of an apparatus suitable for use in producing a film of metal by vacuum evaporation techniques in accordance with the present invention.
- FIG. 2 is a graphical representation on coordinates of time in hours against reflectivity showing diffusion rates for gold-silver thin film couples prepared in accordance with the present invention.
- FIG. 1 shows a suitable vacuum evaporation apparatus for depositing thin films in accordance with the invention.
- a vacuum chamber 11 containing filament l2 and platform 13, which latter is employed as a positioning support for substrate 14.
- Mask 15 is utilized as shown to restrict the deposition of the film to the desired area.
- the ends of filament 12 are connected to electrical leads 16 to permit flow of current therethrough from a source (not shmgn).
- the apparatus also includes an inlet 17 for the introduction of gas during the processing and an outlet 18 for removal of gas, outlet 18 being connected to a suitable pump (not shown).
- the present invention has been described largely in terms of the deposition of gold-silver composites. However, it will be appreciated that such description is solely for purposes of exposition and that any metal capable of being deposited'in thin film form by vacuum evaporation techniques may be obtained in the described manner. Metals found to be particularly useful for thin film applications and amenable to such processing include aluminum, copper, nickel, iron, Pennalloy, etc.
- the invention may conveniently be described by reference to an illustrative embodiment wherein silver and gold are employed as the thin film couple.
- An apparatus similar to that shown in FIG. 1 may conveniently be employed for the purpose of effecting deposition of the films;
- the conditions employed in the vacuum evaporation process are well known .(see Vacuum Deposition of I Thin Films, L. Holland, John Wiley & Sons, Inc., New York, I956).
- the extent of the vacuum is dictatedby consideration of the vapor pressurev of the metal to be evaporated.
- the vapor pressure of the metal to be evaporated should beat least ten times greater than the pressure to which the system is evacuated. In general, better quality films are-obtained at a'higher vacuum.
- themaximum pressure which can be tolerated is that above which the oxygen present inte'rferes-with the deposition of a pure metallic film.
- the usual method of heating the metal to be evaporated is to position it in proximity to a filament which may be heated electrically. This end is conveniently accomplished by using a tungsten filament in the shape of a coil, as shown in FIG. 1, and placing the metal to be evaporated within the coil. The required temperature is obtained by controlling the magnitude of the current flowing through the filament. Alternatively, a filament of the metal to be evaporated may be used in those instances where the metal has a sufficiently high vapor pressure at temperatures below its melting point.
- the substrate member upon which deposition is to be effected may be selected from among glasses, glazed ceramics, high melting metals and any thin film circuitry requiring the deposition of a metal composite thereon.
- the substrate member is first cleaned for the purpose of removing contaminants therefrom, any well-known cleansing technique being suitable for this purpose.
- Substrate 14 is then placed upon platform 13 and mask 15 suitably positioned.
- vacuum chamber 11 is evacuated to a pressure of the order of 10"torr. .and a non-reactive gas admitted thereto.
- non-reactive applies to gases which do not normally enter into chemical reaction with metals. It has been found that argon, helium,
- tungsten filament 12 After the requisite pressure is obtained, a current is passed through tungsten filament 12, thereby heating the filament and causing the metal of interest to evaporate. Evaporation is continued for a time period sufficient to produce a thin film of the desired thickness. Thereafter, at least one additional metal is deposited in the foregoing manner upon the film so produced.
- the thickness of the deposited layers is of no criticality and it is solely dependent upon the specific role that the metal composite is to play in the resultant circuitry.
- This example describes the production of a thin film couple in accordance with the invention wherein gold and silver are successively evaporated upon a substrate.
- the filament being composed of a 5 turn tungsten coil.
- the substrate selected was a glass microscope slide which was cleaned by ultrasonic cleansing in AL- CONOX, and successively boiling in a three part hydrocloric acid-one part SUPEROXOL solution, rinsing in deionized water, vapor drying with isopropyl alcohol and baking at 560 C. for l5 minutes in air to remove residual carbonations material.
- the slide was placed approximately 3% inches from the tungsten filament and a mask placed on the slide.
- a 1 inch piece of gold, 25 mils in diameter was placed within the tungsten filament.
- the vacuum chamber was evaporated to a pressure of approximately 1 X10 torr. and 35 microns of Hg of argon admitted to the chamber. Current was caused to flow through the tungsten filament, heating it to incandescence and causing the evaporation of the gold wire.
- the 1 inch piece of gold wire was completely evaporated within five minutes and a layer of gold 1500 angstroms thick was produced on the exposed portions of the slide. Then, a new tungsten coil was inserted in the apparatus and a silver wire 1 inch in length was inserted in the coil. The evaporation procedure was repeated, so resulting in the evaporation of a layer of silver 5,000
- Optical reflectivity (which is directly related to composition) as a function of time was then measured at the gold-glass interface by conventional techniques. After 49 hours, the reflectivity was found to drop approximately 7 percent, so indicating that a small amount of silver had migrated into the gold film. Thereafter it was found that optical reflectivity remained constant for greater than 5625 hours. 7
- Optical re flectivity was found to decrease approximately 15 percent after 25 hours, 35% after 100 hours and about 45% after 400 hours. Thereafter the optical reflectivity was found to remain constant at that level for greater than 4900 hours.
- Example 1 The procedure of Example 1 was repeated with the exception that helium was employed as the nonreactive gas. Optical reflectivity was found to drop approximately 7 percent after 49 hours and remained constant thereafter for more than 5625 hours.
- FIG. 2 there is shown a graphical representation on coordinates of time in hours against reflectivity in per cent showing variations in optical reflectivity as a function of time (or diffusion rates) for thin film gold-silver couples. It is noted that utilizing 35 and microns of Hg of argon or helium, respectively, as the non-reactive gas in the practice of the present invention results in only a slight decrease in reflectivity as compared with optical reflectivity changes manifested by gold-silver couples evaporated in the absence of such gases.
- a method for reducing interdiffusion rates between thin film conductive components which com-. prises the steps of successively depositing at least two metals capable of being deposited in thin film form by vacuum evaporation upon a suitable substrate by vacuum evaporation techniques in the presence of a nonreactive gas, selected from the group consisting of argon, helium, neon, xenon, krypton, radon and hydrogen, the partial pressure of said gas ranging from 10 to 70 microns.
- a nonreactive gas selected from the group consisting of argon, helium, neon, xenon, krypton, radon and hydrogen, the partial pressure of said gas ranging from 10 to 70 microns.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physical Vapour Deposition (AREA)
- Internal Circuitry In Semiconductor Integrated Circuit Devices (AREA)
Abstract
A method for reducing interdiffusion rates between thin film conductive components. The method comprises vacuum depositing the conductive films at a partial pressure of 10-70 nicrons in the presence of an inert gas (e.g., Argon).
Description
United States Patent 1 1 Theuerer et a]. 1 Aug. 7, 1973 METHOD FOR REDUCING 3,063,858 ll/l962 Sleeves 117 107 INTERDIFFUSION RATES BETWEEN THIN 3,402,073 9/1968 Pierce et al 1 17/217 FILM COMPONENTS OTHER PUBLICATIONS [75] Inventors: Henry C. Theuerer, New York, I
NY; Paul Turner, Murray Hill Holland; L., Vacuum Deposition of Thm Films, N.Y., NIL John Wiley & Sons lnc., l956, pg. 4. 73 Ass'ne: BellTlehneLbo t l 1 lg e f g z z g gs J Primary ExaminerRalph S. Kendall Assistant Examiner-M. F. Esposito [22] Fil d? Apr- 4, 1969 Att0rneyW. L. Keefauver and Edwin B. Cave [21] Appl. No.: 813,421
[57] ABSTRACT 5 I E 3 S 4 22 A method for reducing interd1ffus1on rates between [58] Fie'ld 6 217 227 1 thin film conductive components. The method comprises vacuum depositing the conductive films at a par- [56] Refrences Cited tial pressure of 10-70 nicrons in the presence of an t UNITED STATES PATENTS met (e g Argon) 3,028,663 4/1962 lwersen et al l-l7/l07 5 Claims, 2 Drawing Figures PAIENIEUMIB Hm 1660 HRS H c. THEUERER MEMO P.A. TURNER B) A TTORNEV METHOD FOR REDUCING INTERDIFFUSION RATES BETWEEN THIN FILM COMPONENTS This invention relates to a technique for reducing the interdiffusion rates of thin film components. More particularly, the present invention relates to a technique for reducing the interdiffusion rates between thin film conductive components wherein the components of interest are deposited by vacuum evaporation techniques in the presence of a non-reactive gas.
In recent years, miniaturization of components and circuitry coupled with the increasing complexity of modern electronic systems have created an unprecedented demand for reliability in thin film circuitry and the need for the total exploitation of the technology. This is particularly true in the case of lead attachment which has long been recognized as being a critical factor in the stability of circuit characteristics.
Early workers in the art recognized that the metallurgical compatibility of the various metallic constituents of the joining and conducting system played a prominent role in determining the parameters of interest, so motivating the use of a single metal'for'this purpose. Although such systems were found to be ideal from a metallurgical standpoint, they suffered from inherent defects in that the manufacturer was necessarily restricted from the standpoint of obtaining optimum circuit characteristics. Accordingly, the interest of workers in the art was focused upon multi-metal joining or conducting systems. v
Unfortunately, it has been found that diffusion or the migration of metals in thin film composites through grain boundaries and down dislocation cores drastically alters device characteristics during life performance. Accordingly, workers in the art have long sought to develop techniques for enhancing the stability of thin film structures including thin film conducting composites.
In accordance withthe present invention, the prior art difficulties encountered in connection with such thin film composites have been significantly lessened by a novel technique which causes a reduction in interdiffusion rates between the components of the composite. The inventive technique involves depositing thin film conducting composites by vacuum evaporation techniques in the presence of a suitable non-reactive gas. Studies have revealed that processing in the tile. scribed manner results in the reduction of the diffusivity of metals by segregating diffusion paths and impeding the movement of diffusants by incorporation of the gas of interest in grain boundaries and dislocation cores.
The invention will be more readily understood by reference to the following detailed description taken -in conjunction with the accompanying drawing, wherein:
FIG. 1 is a front elevational view of an apparatus suitable for use in producing a film of metal by vacuum evaporation techniques in accordance with the present invention; and
FIG. 2 is a graphical representation on coordinates of time in hours against reflectivity showing diffusion rates for gold-silver thin film couples prepared in accordance with the present invention.
With reference now more particularly to the drawing, FIG. 1 shows a suitable vacuum evaporation apparatus for depositing thin films in accordance with the invention. Shown in the figure is a vacuum chamber 11 containing filament l2 and platform 13, which latter is employed as a positioning support for substrate 14. Mask 15 is utilized as shown to restrict the deposition of the film to the desired area. The ends of filament 12 are connected to electrical leads 16 to permit flow of current therethrough from a source (not shmgn). The apparatus also includes an inlet 17 for the introduction of gas during the processing and an outlet 18 for removal of gas, outlet 18 being connected to a suitable pump (not shown).
The present invention has been described largely in terms of the deposition of gold-silver composites. However, it will be appreciated that such description is solely for purposes of exposition and that any metal capable of being deposited'in thin film form by vacuum evaporation techniques may be obtained in the described manner. Metals found to be particularly useful for thin film applications and amenable to such processing include aluminum, copper, nickel, iron, Pennalloy, etc.
The invention may conveniently be described by reference to an illustrative embodiment wherein silver and gold are employed as the thin film couple. An apparatus similar to that shown in FIG. 1 may conveniently be employed for the purpose of effecting deposition of the films;
The conditions employed in the vacuum evaporation process are well known .(see Vacuum Deposition of I Thin Films, L. Holland, John Wiley & Sons, Inc., New York, I956). The extent of the vacuum is dictatedby consideration of the vapor pressurev of the metal to be evaporated. In conventional vacuum evaporation processes, it is generally considered that the vapor pressure of the metal to be evaporated should beat least ten times greater than the pressure to which the system is evacuated. In general, better quality films are-obtained at a'higher vacuum. When using metals'with relatively high vapor pressures, themaximum pressure which can be tolerated is that above which the oxygen present inte'rferes-with the deposition of a pure metallic film.
The usual method of heating the metal to be evaporated is to position it in proximity to a filament which may be heated electrically. This end is conveniently accomplished by using a tungsten filament in the shape of a coil, as shown in FIG. 1, and placing the metal to be evaporated within the coil. The required temperature is obtained by controlling the magnitude of the current flowing through the filament. Alternatively, a filament of the metal to be evaporated may be used in those instances where the metal has a sufficiently high vapor pressure at temperatures below its melting point.
It will be understood by those skilled in the art that the substrate member upon which deposition is to be effected, as described, may be selected from among glasses, glazed ceramics, high melting metals and any thin film circuitry requiring the deposition of a metal composite thereon.
The substrate member is first cleaned for the purpose of removing contaminants therefrom, any well-known cleansing technique being suitable for this purpose. Substrate 14 is then placed upon platform 13 and mask 15 suitably positioned. Next, vacuum chamber 11 is evacuated to a pressure of the order of 10"torr. .and a non-reactive gas admitted thereto.
For the purposes of the present invention,it will be understood that the term non-reactive applies to gases which do not normally enter into chemical reaction with metals. It has been found that argon, helium,
neon, xenon, krypton, radon and hydrogen meet these requirements. Studies have indicated that in order to obtain the desired reduction in diffusivity, it is necessary to employ from to 70 microns of Hg of the nonreactive gas. Deviations from the minima and maxima noted fail to yield the required characteristics and result in diffusion rates comparable to those of the prior art.
After the requisite pressure is obtained, a current is passed through tungsten filament 12, thereby heating the filament and causing the metal of interest to evaporate. Evaporation is continued for a time period sufficient to produce a thin film of the desired thickness. Thereafter, at least one additional metal is deposited in the foregoing manner upon the film so produced. The thickness of the deposited layers is of no criticality and it is solely dependent upon the specific role that the metal composite is to play in the resultant circuitry.
Examples of the present invention are described in detail below. These examples and the foregoing illustration are included merely to aid in the understanding of the invention and variations may be made by one skilled in the art without departing from the spirit and scope of the invention.
EXAMPLE NO. 1
This example describes the production of a thin film couple in accordance with the invention wherein gold and silver are successively evaporated upon a substrate.
An apparatus similar to that shown in FIG. 1 was employed, the filament being composed of a 5 turn tungsten coil. The substrate selected was a glass microscope slide which was cleaned by ultrasonic cleansing in AL- CONOX, and successively boiling in a three part hydrocloric acid-one part SUPEROXOL solution, rinsing in deionized water, vapor drying with isopropyl alcohol and baking at 560 C. for l5 minutes in air to remove residual carbonations material.
After cleaning, the slide was placed approximately 3% inches from the tungsten filament and a mask placed on the slide. A 1 inch piece of gold, 25 mils in diameter was placed within the tungsten filament. The vacuum chamber was evaporated to a pressure of approximately 1 X10 torr. and 35 microns of Hg of argon admitted to the chamber. Current was caused to flow through the tungsten filament, heating it to incandescence and causing the evaporation of the gold wire. The 1 inch piece of gold wire was completely evaporated within five minutes and a layer of gold 1500 angstroms thick was produced on the exposed portions of the slide. Then, a new tungsten coil was inserted in the apparatus and a silver wire 1 inch in length was inserted in the coil. The evaporation procedure was repeated, so resulting in the evaporation of a layer of silver 5,000
angstroms thick upon the gold layer. Optical reflectivity (which is directly related to composition) as a function of time was then measured at the gold-glass interface by conventional techniques. After 49 hours, the reflectivity was found to drop approximately 7 percent, so indicating that a small amount of silver had migrated into the gold film. Thereafter it was found that optical reflectivity remained constant for greater than 5625 hours. 7
For comparative purposes, the foregoing procedure was repeated in the absence of the argon. Optical re flectivity was found to decrease approximately 15 percent after 25 hours, 35% after 100 hours and about 45% after 400 hours. Thereafter the optical reflectivity was found to remain constant at that level for greater than 4900 hours.
EXAMPLE NO. 2
The procedure of Example 1 was repeated with the exception that helium was employed as the nonreactive gas. Optical reflectivity was found to drop approximately 7 percent after 49 hours and remained constant thereafter for more than 5625 hours.
With reference now to FIG. 2, there is shown a graphical representation on coordinates of time in hours against reflectivity in per cent showing variations in optical reflectivity as a function of time (or diffusion rates) for thin film gold-silver couples. It is noted that utilizing 35 and microns of Hg of argon or helium, respectively, as the non-reactive gas in the practice of the present invention results in only a slight decrease in reflectivity as compared with optical reflectivity changes manifested by gold-silver couples evaporated in the absence of such gases.
What is claimed is: v
1. A method for reducing interdiffusion rates between thin film conductive components which com-. prises the steps of successively depositing at least two metals capable of being deposited in thin film form by vacuum evaporation upon a suitable substrate by vacuum evaporation techniques in the presence of a nonreactive gas, selected from the group consisting of argon, helium, neon, xenon, krypton, radon and hydrogen, the partial pressure of said gas ranging from 10 to 70 microns.
2. A method in accordance with claim 1 wherein one of said conductive components is gold.
3. A method in accordance with claim 2 wherein one of said conductive components is silver.
4. A method in accordance with claim 3 wherein said gas is argon.
5. A method in accordance with claim 3 wherein said a gas is helium.
Claims (4)
- 2. A method in accordance with claim 1 wherein one of said conductive components is gold.
- 3. A method in accordance with claim 2 wherein one of said conductive components is silver.
- 4. A method in accordance with claim 3 wherein said gas is argon.
- 5. A method in accordance with claim 3 wherein said gas is helium.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US81342169A | 1969-04-04 | 1969-04-04 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3751293A true US3751293A (en) | 1973-08-07 |
Family
ID=25212323
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00813421A Expired - Lifetime US3751293A (en) | 1969-04-04 | 1969-04-04 | Method for reducing interdiffusion rates between thin film components |
Country Status (7)
Country | Link |
---|---|
US (1) | US3751293A (en) |
BE (1) | BE748215A (en) |
DE (1) | DE2015457B2 (en) |
FR (1) | FR2042936A5 (en) |
GB (1) | GB1306113A (en) |
NL (1) | NL145285B (en) |
SE (1) | SE364317B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4407871A (en) * | 1980-03-25 | 1983-10-04 | Ex-Cell-O Corporation | Vacuum metallized dielectric substrates and method of making same |
US4431711A (en) * | 1980-03-25 | 1984-02-14 | Ex-Cell-O Corporation | Vacuum metallizing a dielectric substrate with indium and products thereof |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3028663A (en) * | 1958-02-03 | 1962-04-10 | Bell Telephone Labor Inc | Method for applying a gold-silver contact onto silicon and germanium semiconductors and article |
US3063858A (en) * | 1959-07-22 | 1962-11-13 | Nat Res Corp | Vapor source and processes for vaporizing iron, nickel and copper |
US3402073A (en) * | 1964-08-04 | 1968-09-17 | Texas Instruments Inc | Process for making thin film circuit devices |
-
1969
- 1969-04-04 US US00813421A patent/US3751293A/en not_active Expired - Lifetime
-
1970
- 1970-03-16 SE SE03437/70A patent/SE364317B/xx unknown
- 1970-03-31 BE BE748215D patent/BE748215A/en not_active IP Right Cessation
- 1970-04-01 NL NL707004622A patent/NL145285B/en not_active IP Right Cessation
- 1970-04-01 DE DE19702015457 patent/DE2015457B2/en active Pending
- 1970-04-02 GB GB1560270A patent/GB1306113A/en not_active Expired
- 1970-04-03 FR FR7012228A patent/FR2042936A5/fr not_active Expired
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3028663A (en) * | 1958-02-03 | 1962-04-10 | Bell Telephone Labor Inc | Method for applying a gold-silver contact onto silicon and germanium semiconductors and article |
US3063858A (en) * | 1959-07-22 | 1962-11-13 | Nat Res Corp | Vapor source and processes for vaporizing iron, nickel and copper |
US3402073A (en) * | 1964-08-04 | 1968-09-17 | Texas Instruments Inc | Process for making thin film circuit devices |
Non-Patent Citations (1)
Title |
---|
Holland; L., Vacuum Deposition of Thin Films, N.Y., John Wiley & Sons Inc., 1956, pg. 4. * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4407871A (en) * | 1980-03-25 | 1983-10-04 | Ex-Cell-O Corporation | Vacuum metallized dielectric substrates and method of making same |
US4431711A (en) * | 1980-03-25 | 1984-02-14 | Ex-Cell-O Corporation | Vacuum metallizing a dielectric substrate with indium and products thereof |
Also Published As
Publication number | Publication date |
---|---|
GB1306113A (en) | 1973-02-07 |
DE2015457A1 (en) | 1970-10-08 |
FR2042936A5 (en) | 1971-02-12 |
DE2015457B2 (en) | 1972-02-10 |
NL7004622A (en) | 1970-10-06 |
SE364317B (en) | 1974-02-18 |
NL145285B (en) | 1975-03-17 |
BE748215A (en) | 1970-08-31 |
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