WO2002083975A1 - Apparatus and method for epitaxial sputter deposition of epilayers and high quality films - Google Patents

Apparatus and method for epitaxial sputter deposition of epilayers and high quality films Download PDF

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Publication number
WO2002083975A1
WO2002083975A1 PCT/US2002/011635 US0211635W WO02083975A1 WO 2002083975 A1 WO2002083975 A1 WO 2002083975A1 US 0211635 W US0211635 W US 0211635W WO 02083975 A1 WO02083975 A1 WO 02083975A1
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WIPO (PCT)
Prior art keywords
target
substrate
sputtering
energy
particles
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Application number
PCT/US2002/011635
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French (fr)
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WO2002083975A9 (en
Inventor
Roman Chistyakov
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Telephotonics, Inc.
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Publication date
Application filed by Telephotonics, Inc. filed Critical Telephotonics, Inc.
Publication of WO2002083975A1 publication Critical patent/WO2002083975A1/en
Publication of WO2002083975A9 publication Critical patent/WO2002083975A9/en

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Classifications

    • 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
    • H01J37/3411—Constructional aspects of the reactor
    • H01J37/3414—Targets
    • H01J37/3423—Shape
    • 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
    • C23C14/34—Sputtering
    • C23C14/3407—Cathode assembly for sputtering apparatus, e.g. Target
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
    • C30B23/02—Epitaxial-layer growth
    • 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
    • H01J37/3402—Gas-filled discharge tubes operating with cathodic sputtering using supplementary magnetic fields
    • H01J37/3405—Magnetron sputtering

Definitions

  • the invention relates to the sputtering deposition using a sputtering source with a conical target.
  • a magnetron sputtering source is used to sputter material from a target surface on the substrate to form thin epitaxial layers.
  • the substrates are placed in off axis position to the target surface. Although positioning the substrates in this manner causes the deposition rates to be lower, a much higher quality film is deposited upon the substrate. Higher quality films are used because the substrate surface is not bombarded with high-energy particles, which particles are rejected from the target surface.
  • RF diode sputtering is also used in the production of epitaxial layers.
  • a substrate is also in an off-axis position. This positioning protects the surface of the growing epitaxial layer from bombardment by high-energy particles (negative ions, neutral atoms and electrons) that are released from the cathode.
  • an apparatus for sputtering a thin epitaxial layer onto a substrate includes a sputtering chamber having a sputtering target of a defined thickness.
  • the sputtering chamber produces gas plasma discharge.
  • the positive ions from the sputtering gas bombard the conical target.
  • the sputtered material from the conical target is deposited on the substrate.
  • the target is positioned a defined distance away from the substrate.
  • the target is conically shaped and includes an apex angle.
  • the target is designed to reflect high-energy particles in a direction normal to the surface of the target such that the high- energy particles do not come into contact with the substrate.
  • an apparatus for sputtering a thin film layer onto a substrate includes a sputtering chamber and a substrate receiving surface.
  • the apparatus includes a target disposed in the sputtering chamber that is conically shaped and is designed to reflect high-energy particles in a direction normal to the surface of the target such that the high-energy particles do not come into contact with the substrate on said substrate receiving surface.
  • FIG. 1 is a schematic block diagram of a sputter epitaxy chamber that uses a conical target
  • FIG. 2 is a schematic diagram demonstrating how the conical target reflects high- energy particles.
  • FIG. 1 is a schematic block diagram of a sputter epitaxy chamber 1 that uses a conical target 2. To maintain a gas discharge, gas is pressurized within the chamber 1.
  • the chamber 1 includes a cylindrical outer wall 3 with a top cover 4 and bottom cover 5.
  • the chamber 1 To apply thin film coatings using magnetron sputter deposition, it is first required to evacuate the chamber 1 with a vacuum pump 6 and fill the chamber with a sputtering gas.
  • a gas discharge 7 is established by applying an electrical potential between the target 2 and a cylindrical anode 8.
  • a RF source 9 is electrically connected to the target 2 via a matching network 10.
  • the chamber walls are grounded.
  • the cylindrical anode 8 is mounted on the top cover 4 and is therefore grounded.
  • material of the conical target 2 is deposited upon a substrate 11.
  • the substrate 11 may be mounted essentially parallel to the target plane on the substrate holder 12.
  • the conical target 2 is made from iron garnet.
  • RF diode sputtering sources are widely used for thin film coatings.
  • a gas discharge is established within the chamber 1, thus causing positively charged ions to bombard the conical target surface 2.
  • the collisions of these positively charged ions with the target surface 2 cause material of the target to be released and sputtered on the substrate 11.
  • plasma 13 is formed within the chamber 1.
  • the plasma 13 is located between the conical target 2 and the substrate 11.
  • negatively charged ions are accelerated through the plasma 13, and collide with any object placed directly behind the plasma 13. Due to the amount of energy the negatively charged ions have after they have been accelerated through the plasma 13, they can cause destruction to any surface with which they collide.
  • Another aspect of the sputtering process is that the positive ions in the sputtering gas 7, upon collision with the target surface 2, can combine with electrons and become neutral atoms, in which case they reflect from the target surface 2, hit the surface of the film growing on the substrate 11, and damaging the film.
  • the conical target 2 is designed to specifically deflect high-energy particles reflected from the conical target surface.
  • the conical target 2 includes an apex angle ⁇ that aids in reflecting high-energy negative ions and neutral particles.
  • the distance between the conical target 2 and the substrate 11, diameter of the substrate 11, and the apex angle ⁇ is defined in a relationship, that allows users the flexibility to design conical targets that reflect high-energy particles, to be discussed more below.
  • FIG. 2 is a schematic diagram demonstrating how the conical target 2 reflects high-energy particles.
  • the conical target 2 is shaped specifically as a round conical object. Also, the conical target 2 has a base region 20 and a top region 22. The top region is shaped to be a cone with a defined apex angle ⁇ . The apex angle ⁇ is an important component for reflecting high-energy particles, as described above.
  • the conical target 2 can be comprised of any material used in sputtering, such as oxide compounds.
  • the diameter s of the substrate 11 and the distance d between the conical target 2 and the substrate 11 are essential.
  • the relationship between the apex angle ⁇ , the diameter s of the substrate, and the distance d between the conical target 2 and the substrate 11 is:
  • a conical target 2 is selecting depending on the dimensions of the sputtering chamber 1.
  • the diameter of the substrate 11 and the distance between the conical target 2 and the substrate 11 are known.
  • the apex angle ⁇ is obtained by the equation 1. Therefore, the configuring of the conical target 2 is based on calculating the apex angle ⁇ and devising the height of the conical target 2 based in part on what the allowable distance can be between the substrate 11 and conical target 2.
  • This approach does not require extensive use of equipment to prevent high- energy particles, such negative ions and neutral atoms, from bombarding the substrate 11.
  • the cost of using the invention substantially outweighs the cost of other systems in the prior art.
  • the invention provides an efficient way of producing epilayers used in the production of high quality films or the like.
  • the invention may also be used in a magnetron sputtering system without substantially changing the configuration of the system.
  • magnetron sputtering sources can be redesigned to provide magnetic field lines essentially parallel to the target surface.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Analytical Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Mechanical Engineering (AREA)
  • Physical Vapour Deposition (AREA)

Abstract

An apparatus for sputtering a film layer onto a substrate (11) including a sputtering chamber (1) having a sputtering conical target (2) of a defined thickness. The sputtering chamber (1) produces high-energy particles that bombard the conical target (2). The particles from the target (2) are deposited on the substrate (11). The target (2) is positioned a defined distance away from the substrate (11). The target (2) is designed to reflect high-energy particles in a direction normal to the surface of the target (2) such that the high-energy particles do not come into contact with the substrate (11).

Description

APPARATUS AND METHOD FOR EPITAXIAL SPUTTER DEPOSITION OF EPILAYERS AND HIGH QUALITY FILMS
PRIORITY INFORMATION This application claims priority from provisional application Ser. No. 60/283515 filed April 11, 2001.
BACKGROUND OF THE INVENTION
The invention relates to the sputtering deposition using a sputtering source with a conical target.
A magnetron sputtering source is used to sputter material from a target surface on the substrate to form thin epitaxial layers. However, the substrates are placed in off axis position to the target surface. Although positioning the substrates in this manner causes the deposition rates to be lower, a much higher quality film is deposited upon the substrate. Higher quality films are used because the substrate surface is not bombarded with high-energy particles, which particles are rejected from the target surface.
Another technique for sputtering uses radio frequency (RF) diode sputtering. RF diode sputtering is also used in the production of epitaxial layers. In this method, a substrate is also in an off-axis position. This positioning protects the surface of the growing epitaxial layer from bombardment by high-energy particles (negative ions, neutral atoms and electrons) that are released from the cathode.
SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided an apparatus for sputtering a thin epitaxial layer onto a substrate. The apparatus includes a sputtering chamber having a sputtering target of a defined thickness. The sputtering chamber produces gas plasma discharge. The positive ions from the sputtering gas bombard the conical target. The sputtered material from the conical target is deposited on the substrate. The target is positioned a defined distance away from the substrate. The target is conically shaped and includes an apex angle. The target is designed to reflect high-energy particles in a direction normal to the surface of the target such that the high- energy particles do not come into contact with the substrate. In another aspect of the invention, there is provided an apparatus for sputtering a thin film layer onto a substrate. The apparatus includes a sputtering chamber and a substrate receiving surface. The apparatus includes a target disposed in the sputtering chamber that is conically shaped and is designed to reflect high-energy particles in a direction normal to the surface of the target such that the high-energy particles do not come into contact with the substrate on said substrate receiving surface.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram of a sputter epitaxy chamber that uses a conical target, and
FIG. 2 is a schematic diagram demonstrating how the conical target reflects high- energy particles.
DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a schematic block diagram of a sputter epitaxy chamber 1 that uses a conical target 2. To maintain a gas discharge, gas is pressurized within the chamber 1. In this embodiment, the chamber 1 includes a cylindrical outer wall 3 with a top cover 4 and bottom cover 5.
To apply thin film coatings using magnetron sputter deposition, it is first required to evacuate the chamber 1 with a vacuum pump 6 and fill the chamber with a sputtering gas. A gas discharge 7 is established by applying an electrical potential between the target 2 and a cylindrical anode 8. A RF source 9 is electrically connected to the target 2 via a matching network 10. The chamber walls are grounded. The cylindrical anode 8 is mounted on the top cover 4 and is therefore grounded. Through the sputter deposition process, material of the conical target 2 is deposited upon a substrate 11. The substrate 11 may be mounted essentially parallel to the target plane on the substrate holder 12. In this embodiment, the conical target 2 is made from iron garnet.
RF diode sputtering sources are widely used for thin film coatings. Typically, a gas discharge is established within the chamber 1, thus causing positively charged ions to bombard the conical target surface 2. The collisions of these positively charged ions with the target surface 2 cause material of the target to be released and sputtered on the substrate 11. As a result of the gas discharge, plasma 13 is formed within the chamber 1. The plasma 13 is located between the conical target 2 and the substrate 11.
A large number of sputtered material atoms are released from the target surface 2.
These atoms are deposited on any element in proximity to the conical target 2. During sputtering, negatively charged ions are formed near the conical target 2.
These negatively charged ions are accelerated through the plasma 13, and collide with any object placed directly behind the plasma 13. Due to the amount of energy the negatively charged ions have after they have been accelerated through the plasma 13, they can cause destruction to any surface with which they collide. Another aspect of the sputtering process is that the positive ions in the sputtering gas 7, upon collision with the target surface 2, can combine with electrons and become neutral atoms, in which case they reflect from the target surface 2, hit the surface of the film growing on the substrate 11, and damaging the film.
As mentioned above, one of the problems with using a sputtering process for the formation of epilayers is the high-energy particles bombardment of a growing film. The energy of these particles is in the range of 0.1-3 KeV. The conical target 2 is designed to specifically deflect high-energy particles reflected from the conical target surface. The conical target 2 includes an apex angle α that aids in reflecting high-energy negative ions and neutral particles. The distance between the conical target 2 and the substrate 11, diameter of the substrate 11, and the apex angle α is defined in a relationship, that allows users the flexibility to design conical targets that reflect high-energy particles, to be discussed more below.
FIG. 2 is a schematic diagram demonstrating how the conical target 2 reflects high-energy particles. The conical target 2 is shaped specifically as a round conical object. Also, the conical target 2 has a base region 20 and a top region 22. The top region is shaped to be a cone with a defined apex angle α. The apex angle α is an important component for reflecting high-energy particles, as described above. The conical target 2 can be comprised of any material used in sputtering, such as oxide compounds. In determining the normal direction of reflectance of the conical target 2, the diameter s of the substrate 11 and the distance d between the conical target 2 and the substrate 11 are essential. The relationship between the apex angle α, the diameter s of the substrate, and the distance d between the conical target 2 and the substrate 11 is:
0.5α = tan-1 (s/2d) . Eq. 1 Therefore, using these defined parameters, one can configure a conical target 2 that reflects high-energy particles in a direction approximately normal to the conical target surface without reaching the substrate 11.
Referring to FIG. 1, a conical target 2 is selecting depending on the dimensions of the sputtering chamber 1. In this case, the diameter of the substrate 11 and the distance between the conical target 2 and the substrate 11 are known. The apex angle α is obtained by the equation 1. Therefore, the configuring of the conical target 2 is based on calculating the apex angle α and devising the height of the conical target 2 based in part on what the allowable distance can be between the substrate 11 and conical target 2. This approach does not require extensive use of equipment to prevent high- energy particles, such negative ions and neutral atoms, from bombarding the substrate 11. The cost of using the invention substantially outweighs the cost of other systems in the prior art. Therefore, the invention provides an efficient way of producing epilayers used in the production of high quality films or the like. The invention may also be used in a magnetron sputtering system without substantially changing the configuration of the system. However, magnetron sputtering sources can be redesigned to provide magnetic field lines essentially parallel to the target surface.
Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention.
What is claimed is:

Claims

CLAIMS 1. An apparatus for sputtering a film layer onto a substrate, comprising: a sputtering chamber having a conical target, said sputtering chamber producing bombarding particles that bombard said conical target, wherein particles from said target are deposited on said substrate; said target reflecting high-energy particles in a direction normal to the surface of said target such that said high-energy particles do not come into contact with said substrate.
2. The apparatus of claim 1, wherein the high-energy particles are high-energy neutral atoms.
3. The apparatus of claim 1, wherein the high-energy particles are high-energy electrons.
4. An apparatus for sputtering a film layer onto a substrate, comprising: a sputtering chamber; a substrate receiving surface for holding said substrate; and a conically shaped target disposed in said sputtering chamber, said target reflecting high-energy particles in a direction normal to the surface of said target such that said high-energy particles do not come into contact with said substrate on said substrate receiving surface.
5. The apparatus of claim 4, wherein said target includes top and base regions.
6. The apparatus of claim 4, wherein the high-energy particles are high-energy neutral atoms.
7. The apparatus of claim 4, wherein the high-energy particles are high-energy electrons.
PCT/US2002/011635 2001-04-11 2002-04-11 Apparatus and method for epitaxial sputter deposition of epilayers and high quality films WO2002083975A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US28351501P 2001-04-11 2001-04-11
US60/283,515 2001-04-11

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3988232A (en) * 1974-06-25 1976-10-26 Matsushita Electric Industrial Co., Ltd. Method of making crystal films
JPS63243272A (en) * 1987-03-31 1988-10-11 Sumitomo Light Metal Ind Ltd Magnetron sputtering method
US5753090A (en) * 1995-07-14 1998-05-19 Nihon Shinku Gijutsu Kabushiki Kaisha Small size sputtering target and high vacuum sputtering apparatus using the same
US5919345A (en) * 1994-09-27 1999-07-06 Applied Materials, Inc. Uniform film thickness deposition of sputtered materials

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3988232A (en) * 1974-06-25 1976-10-26 Matsushita Electric Industrial Co., Ltd. Method of making crystal films
JPS63243272A (en) * 1987-03-31 1988-10-11 Sumitomo Light Metal Ind Ltd Magnetron sputtering method
US5919345A (en) * 1994-09-27 1999-07-06 Applied Materials, Inc. Uniform film thickness deposition of sputtered materials
US5753090A (en) * 1995-07-14 1998-05-19 Nihon Shinku Gijutsu Kabushiki Kaisha Small size sputtering target and high vacuum sputtering apparatus using the same

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