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EP0522982B1 - Auf FeGaSi basiertes magnetisches Material mit Ir als Zusatz - Google Patents

Auf FeGaSi basiertes magnetisches Material mit Ir als Zusatz Download PDF

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Publication number
EP0522982B1
EP0522982B1 EP92420217A EP92420217A EP0522982B1 EP 0522982 B1 EP0522982 B1 EP 0522982B1 EP 92420217 A EP92420217 A EP 92420217A EP 92420217 A EP92420217 A EP 92420217A EP 0522982 B1 EP0522982 B1 EP 0522982B1
Authority
EP
European Patent Office
Prior art keywords
magnetic
feirgasi
fegasi
film
thin film
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92420217A
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English (en)
French (fr)
Other versions
EP0522982A3 (en
EP0522982A2 (de
Inventor
Alexander C/O Eastman Kodak Company Zeltser
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Eastman Kodak Co
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Eastman Kodak Co
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Publication date
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Publication of EP0522982A3 publication Critical patent/EP0522982A3/en
Application granted granted Critical
Publication of EP0522982B1 publication Critical patent/EP0522982B1/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00—Thin magnetic films, e.g. of one-domain structure
    • H01F10/08—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers
    • H01F10/10—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition
    • H01F10/12—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition being metals or alloys
    • H01F10/14—Thin magnetic films, e.g. of one-domain structure characterised by magnetic layers characterised by the composition being metals or alloys containing iron or nickel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
    • H01F41/18—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates by cathode sputtering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/14—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for applying magnetic films to substrates
    • H01F41/22—Heat treatment; Thermal decomposition; Chemical vapour deposition

Definitions

  • the present invention relates to a magnetic material suitable for high-density magnetic recording. More specifically, the invention relates to a magnetic head material for high-density recording.
  • Monolithic ferrite has been a material for record heads used in both magnetic disk and tape drives when the coercivity of the recording medium is less than 700 Oersteds (Oe) and the highest frequency is about ten megahertz (MHz).
  • Oe Oersteds
  • MHz ten megahertz
  • NiFe permalloy
  • NiFe has poor wear resistance, and has a relatively low resistivity, causing permeability to decrease rapidly for higher frequencies due to eddy current losses.
  • a sputter-deposited Sendust (FeSiAl) alloy film offers a higher saturation magnetization, about 10 kilogauss (kG). Furthermore, a Sendust alloy has a relatively high resistivity and good wear resistance.
  • FeGaSi has been disclosed as a crystalline magnetic alloy having, compared to Sendust, both a higher saturation magnetization (about 13 kG) and lower coercivity (about 0.1 Oe).
  • a higher saturation magnetization about 13 kG
  • lower coercivity about 0.1 Oe
  • FeGaSi-based alloy film having Ru as an additive there is known in the art an FeGaSi-based alloy film having Ru as an additive.
  • FeRuGaSi has a high saturation magnetization, although somewhat lower than FeGaSi, and an excellent soft magnetic property (low coercivity) suitable for recording in a high frequency range near 100 MHz.
  • FeGaSi in addition to its high-frequency permeability problem, and FeRuGaSi both suffer from a disadvantage in that they lack a meaningful uniaxial anisotropy characteristic.
  • an object of the invention is to provide a magnetic head material without the disadvantages of the prior art in that the head material has both a high saturation magnetization and a high permeability at high frequencies, and is readily suitable as the core material for thin film or laminated magnetic heads.
  • This object is achieved by an FeIrGaSi soft magnetic thin film having a uniaxial magnetic anisotropy of several Oersteds, induced by magnetic annealing of sputtered FeIrGaSi in thin film form.
  • FeIrGaSi in accordance with the invention, is produced initially in sputtered form, with Ir at a concentration level of 1.0 to 4.0 atomic percent, by simultaneously sputtering from an Fe-rich FeGaSi target and an Ir target. After sputter deposition, uniaxial anisotropy is induced by annealing the as-sputtered alloy film in a magnetic field at temperatures between 350 and 600°C in steps of either 25 or 50°C. Prior to annealing, however, a protective layer of SiO2, deposited on the as-sputtered alloy by an RF reactive sputtering method, serves to protect the alloy film from oxidation during annealing.
  • Ir iridium
  • small additions of Ir (up to about four (4) atomic percent) to Fe79Ga6Si15 create an FeIrGaSi film having, compared to the base alloy, improved soft magnetic properties, increased wear resistance, and an elevated Curie temperature.
  • a further important advantage is that FeIrGaSi, after appropriate magnetic annealing, has, unlike FeGaSi, a uniaxial anisotropic characteristic of several Oersteds.
  • FeRuGaSi alloy film whose typical composition varies between Fe72Ru4Ga7Si17 and Fe68Ru8Ga7Si17 (atomic percent), is also known in the art to have a relatively high saturation magnetic induction, and excellent soft magnetic properties, although FeRuGaSi, like FeGaSi, lacks a uniaxial anisotropic characteristic. I have also found, as described in detail hereinbelow, that FeIrGaSi, compared to FeRuGaSi, has a much higher permeability, a smaller coercivity (softer magnetic property), and a higher Curie temperature.
  • Fig. 1 shows generally a thin film 10 of FeIrGaSi, in accordance with the invention, formed on a ceramic substrate 12 by a DC sputtering technique.
  • a layer of silicon dioxide (SiO2) 14 deposited prior to annealing by means of an RF reactive sputtering method to a thickness of approximately 1000 angstroms, serves to protect the alloy film from oxidation during annealing.
  • Fig. 2 shows apparatus 16 for depositing the FeIrGaSi thin film 10 by sputtering.
  • a sputtering chamber 18 includes an electrically conductive holder 20 to which a substrate 22, preferably silicon, is secured.
  • the aforementioned ceramic substrate 12 is secured to the substrate 22, preferably by thermal conductive grease or paste.
  • FeIrGaSi is produced initially in sputtered form by simultaneously sputtering from a target of FeGaSi in bulk form and a target of Ir also in bulk form.
  • a vacuum-cast target 24 comprised of an FeGaSi alloy of a predetermined composition, is situated on an electrically conductive platform 26.
  • one or more thin sheet targets 28 of Ir are secured to the FeGaSi target 24, preferably by spot welding.
  • the number of targets 28 and the composition of the FeGaSi target 24 are determined by the desired concentration of Ir and other elements (Fe,Ga,Si) in the resultant FeIrGaSi alloy to be formed.
  • the FeGaSi target is in the form of a disk having a diameter of approximately 5.7 cm and a thickness of about 0.6 cm; each Ir target is in the form of a 0.5 cm square, with a thickness of 0.25 mm. With targets of those dimensions, each Ir target 28 contributes about 1.3 to 1.6 atomic percent to the FeIrGaSi alloy formed.
  • the targets 24 and 28 may be purchased from Mitsui Comtec Company of Saratoga, California and Morton Thiokol, respectively.
  • the apparatus 16 further comprises a thermionic emitter 38 and an anode 40, to which is connected a DC power supply 42, as shown.
  • a thermionic emitter 38 and an anode 40 to which is connected a DC power supply 42, as shown.
  • Separate sputtering mechanisms serve to excite the combined targets 24 and 28 (FeGaSi and Ir), and the SiO2 target 30.
  • the platform 26 and the platform 20 are connected to a high-voltage DC power source such that the platform 26 is biased strongly negatively relative to the platform 20.
  • the sputtering mechanism for exciting the SiO2 target 30, on the other hand, comprises an RF generator the output of which is connected to the platform 32.
  • a vacuum pump 46 In order to sputter a thin film of FeIrGaSi, a vacuum pump 46 first evacuates the chamber 18; then, argon gas is introduced into the chamber 18 through a valve 48. The argon in the chamber 18 becomes ionized when the power supply 42 applies voltage across the anode 40 and the emitter 38. The ionizing of the gas produces an argon plasma in the chamber 18.
  • a permanent magnet 62 provides a field of a given intensity across the ceramic substrate 12 so that sputtered material is deposited in a direction that establishes an easy axis of the resultant alloy film.
  • the DC power supply 42 is disconnected from the anode 40 and the emitter 38 and the shutter 34 covers the targets 24 and 28.
  • a protective layer of SiO2 is then deposited on the sputtered film of FeIrGaSi.
  • the shutter 36 uncovers the SiO2 target 30 and the generator 44 applies RF power to the electrically conductive platform 32.
  • the RF generator 44 excites residual plasma in the chamber 18, and argon atoms of the plasma now bombard the target 30, thereby ejecting SiO2 molecules which deposit on the FeIrGaSi alloy film covering the substrate 12.
  • a radiant lamp 66 located in the chamber 18 adjacent the substrate 12, functions as a heat source to heat the substrate 12 during RF sputtering of SiO2.
  • a conventional temperature-measuring device 68 such as a thermocouple, continuously monitors the temperature of the substrate 12.
  • the sputtering conditions for forming the thin film of FeIrGaSi and its protective layer of SiO2 are as follows:
  • samples of the FeIrGaSi alloy film, in as-sputtered form with its SiO2 protective film, are subjected to a magnetically annealing process to induce a uniaxial anisotropy into the alloy film.
  • alloy film samples are isothermally annealed for one hour at a temperature that varies from 350°C to 600°C in steps of either 25 or 50°C. After each successive 1-hour step, the samples are cooled to room temperature.
  • all anneals are done in a magnetic field of 250 Oe parallel to the field applied during deposition.
  • An alloy film of FeIrGaSi acquires a uniaxial anisotropic characteristic of several Oersteds after appropriate magnetic annealing of the sputtered alloy in thin film form.
  • Uniaxial anisotropy is a very desirable property since it allows the fabrication of a multilayered or thin film inductive head with an easy axis of magnetization perpendicular to the magnetic flux in the pole tip area.
  • Such a domain wall configuration improves head efficiency, in particular at high frequencies, since magnetization reversal near the pole tips will mainly occur by rotation rather than by domain wall movement.
  • Fig. 3 shows, as a function of annealing temperature, the effect of the Ir content of various FeIrGaSi films on uniaxial anisotropy.
  • Fig. 3 also shows the uniaxial anisotropy for an FeGaSi film (78.7 Fe, 6.3 Ga, and 15.0 Si at. %) and an FeRuGaSi film (69.3 Fe, 7.9 Ru, 6.8 Ga, and 15.9 Si at. %).
  • Each annealing step occurred in 1-hour steps and all samples were cooled to room temperature after each step before anisotropy measurements were taken.
  • Fe 74.0 Ga 8.5 Si 17.5 was the composition of the sputter target 24 to which an additive target was combined.
  • Fig. 4 shows, as a function of annealing temperature, the affect of the Ir content of FeIrGaSi on high-frequency (@150 MHz) permeability. A sample of FeGaSi and a sample of FeRuGaSi are also shown for comparison. Alloy films containing Ir generally exhibit much higher permeability than the FeGaSi and FeRuGaSi films, particularly for 1-hour step annealing between 375 and 550°C.
  • Coercivity is also an important magnetic property of soft magnetic materials and is inversely proportional to the initial permeability if magnetization reversal process is controlled by domain wall movement.
  • Fig. 5 shows coercivity versus annealing temperature of various FeIrGaSi samples, with an FeGaSi and an FeRuGaSi film included for comparison. It can be seen that coercivity is generally independent of film composition and in all films remains below about 0.5 Oe after step annealing for 1 hour between 375 and 550°C. Although there is no dominant trend, coercivity is somewhat smaller in Ir-containing films.
  • a high Curie temperature, T c is desirable for a head material from the point of view of thermal stability of magnetic properties during head fabrication and subsequent usage.
  • the T c of various FeIrGaSi films as well as FeGaSi and FeRuGaSi films are given in the table of Fig. 6. As shown, the addition to an FeGaSi film of Ir up to about 3 at. % generally increases Curie temperature, and the T c of an FeIrGaSi film is higher than the T c of an FeRuGaSi film.
  • FeIrGaSi Various samples of FeIrGaSi have been investigated having Fe as the major component on the basis of relative atomic percent. When expressed as Fe i Ir j Ga k Si l , wherein i, j, k, and l denote relative concentration in atomic percent, it is contemplated that FeIrGaSi, in accordance with the invention, should satisfy the following relationships:

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Thin Magnetic Films (AREA)
  • Magnetic Heads (AREA)
  • Physical Vapour Deposition (AREA)

Claims (6)

  1. Dünnes Filmmaterial mit einer uniaxialen, magnetischen anisotropen Charakteristik, umfassend FeIrGaSi.
  2. Weichmagnetischer dünner FeIrGaSi-Film mit einer uniaxialen, magnetisch anisotropen Charakteristik von mehreren Oersteds, induziert durch magnetische Vergütung von zerstäubtem FeIrGaSi in Form eines dünnen Filmes.
  3. Magnetisches Material, umfassend FeIrGaSi, definiert durch die Eigenschaft einer uniaxialen Anisotropie und verbesserter Hochfrequenz-Permeabilität sowie Abrieb-Widerstandsfähigkeit, hervorgerufen durch magnetische Vergütung von zerstäubtem FeIrGaSi in Form eines dünnen Filmes bei Temperaturen zwischen 350 und 600°C.
  4. Magnetischer Film auf Basis FeGaSi, enthaltend Ir in einer Konzentration von 1,0 bis 4,0 Atomprozenten zur Verbesserung der hochfrequenz-weichmagnetischen Eigenschaft des magnetischen Filmes.
  5. Magnetischer Film auf FeGaSi-Basis mit einer Fe-Dominanz, in dem Fe hauptsächlich ersetzt ist durch Zugabe von Ir in einer Konzentration von 1,0 bis 4,0 Atomprozenten zur Verbesserung der hochfrequenz-weichmagnetischen Eigenschaft des magnetischen Films.
  6. Magnetischer Film auf Basis von FeGaSi, enthaltend Ir in einer Konzentration von weniger als etwa 4,0 Atomprozent, zur allgemeinen Erhöhung der Curie-Temperatur des magnetischen Films.
EP92420217A 1991-07-01 1992-06-25 Auf FeGaSi basiertes magnetisches Material mit Ir als Zusatz Expired - Lifetime EP0522982B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US72406891A 1991-07-01 1991-07-01
US724068 1991-07-01

Publications (3)

Publication Number Publication Date
EP0522982A2 EP0522982A2 (de) 1993-01-13
EP0522982A3 EP0522982A3 (en) 1993-05-12
EP0522982B1 true EP0522982B1 (de) 1995-03-29

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Family Applications (1)

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EP92420217A Expired - Lifetime EP0522982B1 (de) 1991-07-01 1992-06-25 Auf FeGaSi basiertes magnetisches Material mit Ir als Zusatz

Country Status (4)

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EP (1) EP0522982B1 (de)
JP (1) JPH05291038A (de)
KR (1) KR930003179A (de)
DE (1) DE69201836T2 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5411813A (en) * 1993-04-08 1995-05-02 Eastman Kodak Company Ferhgasi soft magnetic materials for inductive magnetic heads

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3465661D1 (en) * 1983-11-02 1987-10-01 Hitachi Ltd Ferromagnetic material, ferromagnetic laminate and magnetic head
DE3681056D1 (de) * 1985-04-11 1991-10-02 Sony Corp Weichmagnetischer duenner film.

Also Published As

Publication number Publication date
JPH05291038A (ja) 1993-11-05
DE69201836D1 (de) 1995-05-04
EP0522982A3 (en) 1993-05-12
KR930003179A (ko) 1993-02-24
DE69201836T2 (de) 1995-12-07
EP0522982A2 (de) 1993-01-13

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