US3484358A - Method and apparatus for reactive sputtering wherein the sputtering target is contacted by an inert gas - Google Patents

Method and apparatus for reactive sputtering wherein the sputtering target is contacted by an inert gas Download PDF

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Publication number
US3484358A
US3484358A US641095A US3484358DA US3484358A US 3484358 A US3484358 A US 3484358A US 641095 A US641095 A US 641095A US 3484358D A US3484358D A US 3484358DA US 3484358 A US3484358 A US 3484358A
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United States
Prior art keywords
plasma
gas
sputtering
cathode
reactive
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Expired - Lifetime
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US641095A
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English (en)
Inventor
Alex Androshuk
Arpad A Bergh
William C Erdman
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AT&T Corp
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Bell Telephone Laboratories Inc
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
    • H01L23/29—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the material, e.g. carbon
    • 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
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • 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
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
    • C23C16/503—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using dc or ac discharges
    • 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
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—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
    • 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
    • Y10S148/158—Sputtering
    • 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
    • Y10S422/00—Chemical apparatus and process disinfecting, deodorizing, preserving, or sterilizing
    • Y10S422/906—Plasma or ion generation means

Definitions

  • Gas plasmas are finding ever-increasing uses. They have been used for some time in cathodic sputtering and related processes for depositing thin films. Exemplary plasma deposition processes are described and claimed in United States Patent 3,287,243, issued Nov. 22, 1966; and an application being filed concurrently herewith by A. Androshuk, A. A. Bergh and W. C. Erdman, Serial No. 641,094, filed Apr. 28, 1967, and now US. Patent 3,424,661. The effectiveness of high energy plasmas in promoting various chemical reactions at unusually low temperatures has long been recognized. It appears likely that high energy plasma processes will become increasingly important in thin film technology where pyrolytic processes have been dominant.
  • the cathode has a limited elfective life.
  • the foregoing difliculties are, in whole or part, overcome by continuously flowing a protective gas over the surface of the cathode While 3,484,358 Patented Dec. 16, 1969 "ice the plasma reaction proceeds.
  • the anode may be similarly treated.
  • the presence of the protective gas prevents the plasma from contacting the electrode and corroding it without interfering with the electrical discharge of electrons or cathode material.
  • the figure is a perspective view of the reaction chamber of an apparatus useful according to one embodiment of the invention.
  • the apparatus shown in the figure consists essentially of a main reaction chamber 10 and two side chambers 11 and 12 for containing the electrodes.
  • the main chamber 10 contains a pedestal 13 upon which the substrate 14 is supported.
  • the material from which the pedestal is made is not critical. It is helpful that it be a good heat conductor. Silicon, aluminum, molybdenum, carbon, and brass and copper if cooled, are appropriate materials. It is also convenient from the sandpoint of avoiding contamination of the substrate that the pedestal and substrate be of the same material.
  • An RF heater 15 is disposed outside the quartz tube inductively coupled with the pedestal for heating the substrate.
  • the chamber 11 contains the anode 16 which is merely a block of a conductive material such as aluminum.
  • the chamber 12 contains the cathode which may be any appropriate electron emitter. It may be an electrode similar to the anode or a thermionic emitter.
  • the cathode composition and structure are not critical.
  • the sole function of the two electrodes in the process and apparatus of this embodiment of the invention is to support the reactive gas plasma. Neither electrode participates in the chemical reaction or directs the flow of free ions. Consequently the two electrodes can advantageously be isolated from the reaction region. This isolation is achieved by creating a protective gas atmosphere around each electrode with the reactive gas plasma confined to the main reaction chamber 10 where deposition is desired. This feature provides some important advantages. Impurities on or in either electrode cannot reach the region of the substrate to contaminate the deposit. More importantly, the electrodes themselves are not consumed, corroded or passivated by direct exposure to the reactive gas plasma.
  • the protective gas for the electrodes is provided, in the apparatus of the figure, by flowing an appropriate gas such as argon, helium or nitrogen through inlet ports 18 and 19 in the electrode chambers 11 and 12 respectively. Any of the other inert gases can be used as well. Gases such as carbon dioxide, air or other gases while are relatively inert to the electrode material can be used as well. It will be appreciated that the presence of an inert gas in the cathode chamber enables the use of a conventional thermionic electron emitter.
  • the gas reactants for the plasma are admitted through the gas inlet port 20.
  • the reactants are chosen according to the reaction desired.
  • the interface between the protective gas enveloping the electrodes and the reactive gas plasma is maintained by balancing the flow rates of the gases against a vacuum pump connected to the common exhaust ports 21 and 22.
  • the boundary of the plasma is easily recognized by visual observation and adjusted by varying the relative flow rates until the interface reaches the desired position. It is convenient to operate with the plasma boundary in the vicinity of the exhaust ports 21 and 22.
  • the following example is directed to a specific process for depositing a thin silicon nitride film on a silicon substrate and illustrates one practical use of the method and apparatus of this invention for creating a reactive gas plasma.
  • Pressures which give a useful plasma can be prescribed by the range 0.1 torr to 10 torr.
  • the amount of SiBr was 0.1 percent by volume of the nitrogen gas. It was found that this parameter could be varied from 0.01 percent to 1 percent to give satisfactory results.
  • the plasma was initiated with a Tesla coil between a water-cooled aluminum anode and the cathode at a voltage of 200 volts and a current of 1 ampere.
  • the cathode was a U4 electron tube filament drawing amperes at 5 volts.
  • the argon gas flow rate was adjusted until the plasma extended approximately between the two exhaust ports 21 and 22. The short mean free path of the gas molecules at these pressures and the opposing gas fiow arrangement prevent the diffusion of the reactive gases into the anode and cathode compartments.
  • the silicon substrate was placed so as to be completely immersed in the plasma.
  • An alnico magnet with a field of 2000 to 3000 gauss was mounted on the top of the reaction chamber to deflect the plasma to the region of the substrate. This is an optional expedient which is related to the geometry of the particular apparatus being used. Obviously if the plasma extends unnecessarily beyond the region of the substrate there is a waste of power and gas reactants.
  • the protective gas layer for the anode is less important and in fact is unnecessary in many instances. Where the plasma is used to deposit a film on the anode the protective gas layer will usually be found to be helpful on the cathode only.
  • the sputtering rate can be increased considerably. Silicon sputters more rapidly in argon than in oxygen or nitrogen. Since the rate-determining factor is the rate of ejection of material at the cathode surface, the use of an argon envelope around the cathode increases the rate appreciably. Exemplary processes for which the invention can be adapted are described and claimed in United States Patent Nos. 3,073,770 for depositing mullite and 3,242,006 for depositing tantalum nitride.
  • a method of reactively sputtering comprising the steps of mounting two electrodes including a sputtering target of the material to be sputtered spaced from one another in a vacuum chamber, flowing a protective gas into contact with the surface of at least the sputtering target, the protective gas having a composition which is substantially inert to the sputtering target providing the reactive gas in the space between the elecrodes and generating an electric discharge between the two electrodes through the reactive gas while maintaining at least one of the electrodes immersed in the protective gas, and supporting a substrate in the portion of the discharge comprising the reactive gas, whereby particles being sputtered from said target migrate into contact with reactive gas and combine therewith deposit in compound form on said substrate.
  • the protective gas is argon, helium or nitrogen.
  • An apparatus for reactively sputtering comprising a closed reaction chamber, vacuum means for estatblishing a vacuum in said chamber, at least two spaced electrodes in the chamber, including a sputtering target, means for flowing a reactive gas through a portion of the region between the two electrodes, said portion defining a reaction region, means for flowing a protective gas to completely envelop at least said sputtering target, the protective gas having a composition which is relatively inert to the sputtering target the apparatus being adapted so that the fiow rate of the reactive gas and the protective gas are such that a static gas interferface will exist between the said reaction region and at least sputtering target electrical means for creating an electrical discharge between said electrodes so as to ionize the reactive gas, causing material to be sputtered from said target, and means to support a substrate in said reactive gas, whereby particles being sputtered from said target migrate into contact with said reactive gas and combine therewith to deposit in compound form on said substrate.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Plasma & Fusion (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Analytical Chemistry (AREA)
  • Packages (AREA)
  • Chemical Vapour Deposition (AREA)
  • Physical Vapour Deposition (AREA)
US641095A 1966-09-01 1967-04-28 Method and apparatus for reactive sputtering wherein the sputtering target is contacted by an inert gas Expired - Lifetime US3484358A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US57945266A 1966-09-01 1966-09-01
US64109567A 1967-04-28 1967-04-28

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US (1) US3484358A (es)
BE (1) BE700937A (es)
BR (1) BR6792541D0 (es)
CH (1) CH468769A (es)
DE (1) DE1639042B2 (es)
ES (1) ES344947A1 (es)
GB (1) GB1202572A (es)
IL (1) IL28232A (es)
MY (1) MY7100087A (es)
NL (1) NL142016B (es)
NO (1) NO123048B (es)
SE (1) SE317237B (es)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3664895A (en) * 1969-06-13 1972-05-23 Gen Electric Method of forming a camera tube diode array target by masking and diffusion
US3925187A (en) * 1971-03-25 1975-12-09 Centre Nat Etd Spatiales Apparatus for the formation of coatings on a substratum
US4579609A (en) * 1984-06-08 1986-04-01 Massachusetts Institute Of Technology Growth of epitaxial films by chemical vapor deposition utilizing a surface cleaning step immediately before deposition
US4961832A (en) * 1989-03-14 1990-10-09 Shagun Vladimir A Apparatus for applying film coatings onto substrates in vacuum

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3049488A (en) * 1959-01-12 1962-08-14 Ici Ltd Method of conducting gaseous chemical reactions
US3051639A (en) * 1958-09-25 1962-08-28 Union Carbide Corp Arc torch chemical reactions
US3294669A (en) * 1963-07-22 1966-12-27 Bell Telephone Labor Inc Apparatus for sputtering in a highly purified gas atmosphere
US3390980A (en) * 1964-01-20 1968-07-02 Mhd Res Inc Method of producing beryllium halides from beryllium ore in a high intensity ore

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3051639A (en) * 1958-09-25 1962-08-28 Union Carbide Corp Arc torch chemical reactions
US3049488A (en) * 1959-01-12 1962-08-14 Ici Ltd Method of conducting gaseous chemical reactions
US3294669A (en) * 1963-07-22 1966-12-27 Bell Telephone Labor Inc Apparatus for sputtering in a highly purified gas atmosphere
US3390980A (en) * 1964-01-20 1968-07-02 Mhd Res Inc Method of producing beryllium halides from beryllium ore in a high intensity ore

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3664895A (en) * 1969-06-13 1972-05-23 Gen Electric Method of forming a camera tube diode array target by masking and diffusion
US3925187A (en) * 1971-03-25 1975-12-09 Centre Nat Etd Spatiales Apparatus for the formation of coatings on a substratum
US4579609A (en) * 1984-06-08 1986-04-01 Massachusetts Institute Of Technology Growth of epitaxial films by chemical vapor deposition utilizing a surface cleaning step immediately before deposition
US4961832A (en) * 1989-03-14 1990-10-09 Shagun Vladimir A Apparatus for applying film coatings onto substrates in vacuum

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Publication number Publication date
DE1639042B2 (de) 1971-05-19
IL28232A (en) 1970-10-30
BR6792541D0 (pt) 1973-06-26
NL142016B (nl) 1974-04-16
SE317237B (es) 1969-11-10
GB1202572A (en) 1970-08-19
CH468769A (de) 1969-02-15
MY7100087A (en) 1971-12-31
NO123048B (es) 1971-09-20
BE700937A (es) 1967-12-18
ES344947A1 (es) 1968-11-01
DE1639042A1 (de) 1970-02-26
NL6710208A (es) 1968-03-04

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