MAGNETIC THIN FILM AND METHOD OF MANUFACTURING THE SAME

Abstract: An organic metal compound containing elements constituting a magnetic material and an oxygen gas are introduced into plasmas at a low pressure and a thin film of magnetic oxide is prepared on an organic film or aluminum at low temperature.

Description: This invention concerns a magnetic thin film capable of recording data at high density for use in storage media such as video tapes, magnetic discs and optomagnetic discs, and a method of manufacturing the same. Magnetic recording has been directed to higher density and digital recording in recent years. Magnetic recording method mainly employed so far has been the so-called interplaner magnetization method in which directions of easy magnetization exist on a plane of a magnetic recording medium. However, since the directions of magnetization in the magnetic recording medium are oriented so as to repell with each other as the recording density is increased in this system, it has been difficult to increase the recording density. In view of the above, a magnetic recording method called perpendicular magnetization, in which directions of easy magnetization are in the direction perpendicular to the plane of the magnetic recording medium, has been recently developed as a new magnetic recording method, which has enabled to outstandingly increase the recording density as disclosed in "An Analysis for the Mangetization Mode for High Density Magnetic Recording", by S. Iwasaki and Y. Nakayama, IEEE Transaction, Magn. MAG-13, No. 5, p 1272 (1977). A cobalt-chromium (Co-Cr) alloy film has been developed as the perpendicular magnetic recording recording medium mainly by a sputtering process as disclosed in "Co-Cr Recording Film with Perpendicular Magnetic Anisotropy", by S. Iwasaki and K. Ouchi, IEEE Transaction, Magn. MAG-14, 5, 849 (1978). In addition to the Co-Cr alloy, barium ferrite (BaO.6FE₂O₃) has been obtained by the sputtering process as disclosed in "Structure and Magnetic Property of C-Axis Oriented Ba-Ferrite Film by an Opposed Target Type Sputtering", by Matsuoka, Naoe and Yamanaka, The Transactions of the Institute of Electronics and Communication Engineers of Japan (C), J. 66-C, 1, p 9 - 16 (January 1983). In these perpendicular magnetic recording media, although the Co-Cr alloy film can be prepared at a low temperature, the perpendicular magnetic anisotropy thereof as the measure for the magnitude of the perpendicular magnetization is smaller than that of barium ferrite and strontium ferrite. This causes a problem that no complete perpendicular magnetization film can be obtained, but some inplanar magnetized components remain. Further, since the Co-Cr alloy is a metal material, it is readily oxidized as other magnetic materials such as Fe and Co-Ni. While on the other hand, a substantially complete perpendicular magnetization film can be prepared with barium ferrite and strontium ferrite since a substantially complete C-axis oriented film can be obtained therewith. However, since the substrate temperature has to be 500°C or higher for preparing a barium ferrite or strontium ferrite film, it is difficult to prepare strontium ferrite or barium ferrite on a polyimide or aluminum substrate. While on the other hand, the perpendicular magnetization is necessary also in the optothermal magnetic recording for attaining high density recording. However, the optothermal magnetic recording method is different from the magnetic recording method in that the change in the magnetic property due to the heat application is utilized for recording and the optical effect relevant to the magnetic property is utilized for reproducing. That is, heat of a laser beam is utilized for recording and Kerr effect or Faraday's effect of the optomagnetic recording medium is utilized for reproduction as disclosed by Osamu Imamura, The Journal of the Institute of Television Engineers of Japan, Vol. 39, No. 4 (1985), p 365 - 368. Further, if an optomagnetic disc is used, for example, as the medium, a large Kerr effect (large Kerr rotation angle) is required in order to improve the SN ratio (signal to noise ratio) of the disc as disclosed by Masanori Abe, the Journal of the Magnetics Society of Japan, Vol. 8, No. 5 (1984), p 366 - 372. In view of the above, optomagnetic recording media with large Kerr rotation angle such as manganese-bismuth (MnBi), gadolinium-cobalt (GdCo) and gadolinium-terbium-iron (GdTbFe) have been developed by the vacuum deposition or sputtering process. However, since these recording media utilize metal thin films such as Gd, Tb and Fe which are readily oxidized, they are considered not adaptable to external memory devices or the like for computers that require high reliability. While on the other hand, it has been attempted to use ferromagnetic oxides, which are highly stable chemically, as the optomagnetic or magnetic recording (medium as disclosed by) J.W.D. Maltens and A.B. Voermans, IEEE Transactions on Magnetics, vol. MAG-20 No. 5, September, 1984, and mainly cobalt ferrite films or oxide iron films are prepared by a heat treatment at 400°C - 800°C using a sputtering or gas phase heat decomposing process (by H. Schmid in Austrian Patent No. 162,382 (1949), and R. H. Samyer in U.S. Patent No. 2642339 (1953). In these optothermo magnetic recording media, although MnBi, GdCo and GdTbFe alloys can produce perpendicular magnetization films through synthesis at lower temperature, there has been a problem that the reliability is reduced due to the oxidation of the film. Particularly, in the case of using inexpensive substrates such as of polycarbonate or polyimide, these substrates are liable to adsorb water and, accordingly, the alloys may be oxidized due to the absorbed water. While on the other hand, ferrites such as cobalt ferrite are free from oxidation of the films and, stable and inexpensive. However, since a heat treatment at 700°C -800°C (crystallization) is necessary upon preparing the film through sputtering or chemical vapor deposition process (CVD process) for obtaining a film of a large Kerr effect, it is difficult to use those substrates, for example, made of low melting glass, aluminum, polycarbonate and polyimide. In addition, since the ferrites such as cobalt ferrites have a spinel type isotropic crystal structure, there is a problem that they cannot form a perpendicular magnetization film by the crystal magnetic anisotropy such as in barium ferrite or Co-Cr. The preparation and properties of hexaferrite films is discussed by R. C. Taylor and V. Sadagopan in J. Electrochem Soc. , Vol. 119, No. 6, pp. 788-790 (1972). A method is disclosed of depositing, by chemical vapour deposition (CVD), a thin film of PbFe₁₂O₉ (Magnetoplumbite) onto a crystal sapphire substrate. The method involves the pyrolysis of iron penta carbonyl and tetraethyl lead in the presence of oxygen. The optical properties of the hexaferrite films make them useful in semi-transparent photomask (STP) applications, and their potential application in the area of magnetic domain devices is also disclosed. A method of applying a ferromagnetic surface coating to a non-magnetizable base, such as a tape, disk or cylinder, is disclosed in US patent 2,919,207. The method consists of depositing the ferromagnetic coating on a surface of the base by exposing the surface, at a decomposition temperature of the carbonyl compound of the desired metal, to the carbonyl compound in gaseous form. The carbonyl compound is decomposed at the surface of the base to form a homogeneous coating of the magnetizable metal. An object of this invention is to pro-de a reliable magnetic oxide film. Another object of this invention is to provide a method of manufacturing a reliable magnetic oxide film by use of a plasma chemical vapor deposition process on a substrate with a low heat resistivity such as an organi film or aluminum at a low temperature or without heating the substrate. According to this invention there is provided a method of manufacturing a magnetic thin film by deposition on a substrate from a mixture of a metallic compound and oxygen, characterised by: decomposing a gas of a metal compound containing elements constituting a magnetic material and oxygen as a reaction gas in high frequency plasmas, magnetron discharge plasmas or electron cyclotron plasmas under a low pressure from 10 to 10⁻⁴ torr, while heating the substrate at a low temperature below 350°C or without heating the substrate, thereby depositing a thin film of magnetic oxide on the substrate. The invention also provides a magnetic thin film obtainable by the above method. Specifically, organic metal compounds containing elements constituting the magnetic material, for example, alkoxide compounds such as triethoxy iron (Fe(OC₂H₅)₃), triethoxy cobalt (Co(O C₂H₅)₃), diethoxy barium (Ba(o C₂H₅)₂), B-diketone complexes such as dipivaloyl methane barium (Ba(DPM)₂) (DPM=C₁₁H₁₉)₂), iron acetyl acetonate (Fe(C₅H₇O₂)₃), cobalt acetyl acetonate (Co(C₅H₇O₂)₃) and barium acetyl acetonate (Ba(C₅H₇O₂)₂) and ferrocene-like compounds such as bis (cyclopentadienyl) iron (Fe(C₅H₅)₂) and bis (cycloppentadienyl) cobalt (Co(C₅H₅)₂) in the form of vapors are introduced together with oxygen (O₂) as the reaction gas into a reaction vessel at a reduced pressure, and plasmas are generated in the reaction vessel to deposit magnetic oxide material on a substrate at a low temperature below 350°C. For instance, when cobalt ferrite (CoFe₂O₄) is prepared through the reaction of iron acetyl acetonate, cobalt acetyl acetonate and oxygen, the reaction proceeds by the following reaction scheme : 8Fe (C₅H₇O₂)₃ + 4 Co(C₅H₇O₂)₃ + 233O₂ --→ 4CoFe₂O₃ + 180CO₂ + 126H₂O If the heat decomposing reacton is carried out under the normal pressure (760 Torr), a temperature at 500°C or higher is required for the substrate, but the reaction can occur in plasmas at a temperature from 100°C to 350°C under a reduced pressure (10 Torr - 10⁻⁴ Torr), and, further, the reaction occurs at a temperature below 100°C in high density plasmas such as magnetron discharge plasmas and electron cyclotron resonance plasmas. The oxide magnetic film can thus be deposited under a low temperature, because there are present in plasmas many chemical species such as active radicals or ions that cause chemical reactions at low temperature, and the reaction that cannot occur in view of the energy in the usual heat CVD process is possible within the plasmas. In addition, the plasma CVD process can synthesize high melting materials such as oxides, carbides and nitrides at low temperature as compared with the usual CVD process, as well as can produce film of columnar structure at high purity and with good crystallinity even at a low temperature since this accompanies heat decomposing deposition. Thus, this is a most suitable method to render the magnetization film of isotropic crystal structure such as ferrites (horizontal magnetization film) into a perpendicular magnetization film on an organic film (since ferrites are isotropic crystals, perpendicular magnetization film is obtained by utilizing the perpendicular anisotropy caused by the configurational anisotropy due to the columnar structure of the film). With the constitution as has been described above, a thin magnetic oxide film (perpendicular magnetic recording medium) can be obtained at a low temperature below 350°C by skillfully utilizing the plasma activity in the method according to this invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic structural view of a plasma CVD device used in the manufacturing method according to this invention; and Figure 2 is a schematic cross sectional view of a thin film of a magnetic oxide material obtained by the manufacturing method according to this invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 Figure 1 shows a schematic structural view of a plasma CVD device used according to this invention. In Figure 1, there are shown a reaction chamber 11, a high frequency electrode 12, a high frequency power source 13, a substrate heating holder 14, a substrate 15 and bubblers 17, 18, 19 for raw material gases, an Ar carrier gas bomb 19, an O₂ reaction gas bomb 20 and a rotary pump 21. At first, diethoxy barium (Ba(OC₂H₅)₂) and triethoxy iron (Fe(OC₂H₅)₃) as organic metal compounds were respectively charged in the bubblers 16 and 17 filled with ethanol (C₂H₅ OH). A bubbling Ar gas 19 was caused to flow at 200 cc/minute and these vapors were introduced by means of the rotary pump 21 onto a polyimide substrate heated to 350°C within the reaction chamber 11 under a reduced pressure. Then, oxygen 20 also as a reaction gas was caused to flow at a flow rate of 200 cc/min. also on a glass substrate and then introduced to the inside of the reaction chamber 11. The gas pressure was 10 Torr in this case. Then, high frequency power (13.65 MHz) was applied at 500 W (5 W/cm²) for 60 min. to cause a reaction. The thickness of the barium ferrite film deposited on the polyimide substrate was about 2.5µm. Magnetic properties of the film were then measured by X-ray analysis and VSM (vibration sample type magnetic force meter) and the results are shown in Tables 1 (a) and (b) as Sample No. 1. In the similar manner, the result of the measurement for the film thickness, X-ray analysis and VSM while varying the substrate temperature, bubbler amount (Ar flow rate) of Ba(OR)₂ and Fe(OR)₃, pressure in the reaction chamber and high frequency power are shown in Tables 1 (a) and (b) as Sample Nos. 2 - 8. The Sample Nos. 9 - 16 represent Comparative Examples other than this invention. X-ray analysis was conducted to examine whether the C-axis orientation had been obtained at the single phase of the barium ferrite. Further, from the result of VSM, the saturation magnetism and hysteresis curve (B-H curve) of the barium ferrite were obtained to determine the residual magnetism in the perpendicular direction and the residual magnetism in the horizontal direction. (If the residual magnetism in the perpendicular direction is larger compared with the residual magnetism in the horizontal direction, the perpendicular magnetization film is more excellent. Example 2 In the plasma CVD device shown in Figure 1, the bubbler 16 was used for Sr(OR)₂ and the bubbler 17 was used for Fe(OR)₃. At first, diethoxy strontium (Sr(O C₂H₅)₂) and triethoxy iron (Fe(O C₂H₅)₃) were placed in the bubblers 16 and 17 containing ethanol (C₂H₅OH) respectively (30 wt% solution of Sr(O C₂H₅)₂ and Fe(O C₂H₅)₃). Bubbling argon gas was caused to flow at 20 cc/min and 200 cc/min respectively, and these vapors were introduced onto a polyimide substrate heated to 350°C in the reaction chamber 11 under a reduced pressure. Then, oxygen 20 as another reaction gas was caused to flow at a flow rate of 200 cc/min also on a glass substrate and introduced to the inside of the reaction chamber 11. The gas pressure was 10 Torr. Then, high frequency power (13.65 MHz) was applied at 500 W (5 W/cm²) for 60 minutes to cause reaction. The thickness of the strontium ferrite film deposited on the polyimide substrate was about 2.0µm. Then, magnetic properties of the film were measured by X-ray analysis and VSM (vibration sample type magnetic force meter). The results are shown in Tables 2 (a) and (b) as Sample No. 1. In the similar manner, the result of the measurement for the film thickness, X-ray analysis and VSM while varying the substrate temperature, bubbler amount (Ar flow rate) of Ba(OR)₂ and Fe(OR)₃, pressure in the reaction chamber, high frequency power, etc. are shown in Tables 2(a) and (b) as Sample Nos. 2 - 8. The sample Nos. 9 - 16 represent Comparative Examples other than this invention. X-ray analysis was conducted to examine whether the C-axis orientation had been obtained at the single phase of the strontium ferrite. Further, from the results of VSM, the saturation magnetization and hysteresis curve (B-H curve) of the strontium ferrite were determined to obtain the residual magnetism in the perpendicular direction and the residual magnetism in the horizontal direction. (If the residual magnetism in the perpendicular direction is larger than the residual magnetism in the horizontal direction, the perpendicular magnetism film is more excellent. Example 3 In the plasma CVD device shown in Figure 1, the bubbler 16 was used for Fe(OR)₃ or a mixture of Fe(C₅H₇O₂)₃ and Ba(OR)₂ or Ba(C₅H₇O₂)₂; the bubbler 17 was used for Co(OR)₃ or Co(C₅H₇O₂)₃; and the bubbler 18 was used for Zn(OR)₄ or Zn(C₅H₇O₂)₂. At first the bubbler 16 containing a mixture of triethoxy iron (Fe(O C₂H₅)₃) and diethoxy barium (Ba(O C₂H₅)₂) and the bubblers 17, 18 containing diethoxy cobalt (Co(O C₂H₅)₃) and diethoxy zinc (Zn(O C₂H₅)₂) were heated to 150°C. Bubbling argon gas 19 was caused to flow at 250 cc/min, 80cc/min, 10cc/min and 10cc/min respectively to these bubblers, and these vapors were introduced by way of a rotary pump on a polyimide substrate heated to 345°C in the reaction chamber 11 under a reduced pressure. Then, oxygen 20 as another reaction gas was caused to flow at a flow rate of 250 cc/min also on the polyimide substrate. The gas pressure was 10 Torr. Then, high frequency power (13.65 MHz) was applied at 500 W (5 W/cm²) for 60 minutes to cause a reaction. The thickness of the hexagonal ferrite film deposited on the polyimide substrate was about 2.4 µm. Then, magnetic properties of the film were measured by X-ray analysis and VSM (vibration sample type magnetic force meter). The results are shown in Tables 3 (a) - (d) as Sample No. 1. In the similar manner, the results of the measurement for the film thickness, X-ray analysis and VSM while varying the substrate temperature, bubbler amount (Ar flow rate) for Ba(OR)₂ and Fe(OR)₃, pressure in the reaction chamber, high frequency power, etc. are shown in Tables 3 (a) - (d) as Sample Nos. 2 - 12. The Sample Nos. 13 - 19 represent Comparative Examples other than this invention. X-ray analysis was conducted to examine whether the C-axis orientation had been obtained at the single phase of the hexagonal ferrite. Further, from the results of VSM, the saturation magnetization and hysteresis curve (B-H curve) of the hexagonal ferrite were determined to obtain the residual magnetism in the perpendicular direction and the residual magnetism in the horizontal direction. (If the residual magnetism in the perpendicular direction is larger than the residual magnetism in the horizontal direction, the perpendicular magnetization film is more excellent. Example 4 In the plasma CVD device shown in Figure 1, the bubbler 16 was used for cobalt-containing alkoxide or cobalt-containing β-diketone metal chelate; the bubbler 17 was used for iron-containing alkoxide or iron-containing metal chelate; and the bubbler 18 was used for M-containing alkoxide (where M is one of Al, Cr, Gd, Mn and In) or M-containing metal chelate. At first, triethoxy cobalt (Co(O C₂H₅)₃), triethoxy iron (Fe(O C₂H₅)₃) and triethoxy aluminum (Al(O C₂H₅)₃) were charged in the bubblers 16, 17 and 18 heated to 150°C respectively. Bubbling argon gas 19 was caused to flow at 100 cc/min, 200 cc/min and 5 cc/min respectively and the vapors were introduced onto the aluminum substrate 15 heated to 300°C in the reaction chamber 11 at a reduced state. Then, oxygen (O₂) 20 as another reaction gas was caused to flow at a flow rate of 200 cc/min also on the aluminum substarte to conduct reaction for 6 minutes. The gas pressure was 1.0 Torr and the high frequency power (13.56 MHz) was 500 W (5 W/cm²). The thickness of the cobalt ferrite film deposited on the substrate was 2100 Å and then SiO₂ film was deposited thereover to 2150 Å by sputtering. Then, X-ray analysis for the crystal structure and the measurement of the Kerr rotation angle (measured for entering laser beams at wavelength of 780 nm onto the SiO₂ film, reflecting at the aluminum surface and then detecting the laser beams permeated through the SiO₂ film again for measurement) were carried out. The results are shown in Tables 4 (a) and (b) as Sample No. 1. In the same manner, the results of the X-ray analysis and the Kerr effect (magnitude of the Kerr rotation angle) were measured while varying the substrate temperature, type of the alkoxide, type of the β-diketone metal chelate, amount of bubbler (Ar flow rate), pressure in the reaction chamber, high frequency power, etc. are shown in Tables 4 (a) and (b) as Sample Nos. 2 - 21. Sample Nos. 22 - 25 are Comparative Examples other than this invention. The X-ray analysis was carried out for examining the crystal structure and the orientation of the film of the cobalt ferrite, as well as the solid-solubilized state of the additives M (where M represents one of Al, Cr, Fe, Gd, Mn and In). The Kerr effect (magnitude of the Kerr rotation angle) was examined by a polarized plane modulation method (for example, as disclosed by Imamura in the Journal of the Institute of Television Engineers of Japan, Vol. 39, No. 4, 1985, 366p). Further, it was also examined by the magnetic property of the film (B-H curve) due to VSM (vibration sample type magnetic force meter) whether the cobalt ferrite film was perpendicular magnetization film or not. Example 5 In the plasma CVD device shown in Figure 1, the bubbler 16 was used cobalt-cotaining chelate; the bubbler 17 was used for iron-containing iron-chelate; and the bubbler 18 was used for M-containing chelate (where M is one of Al, Cr, Gd, Mn and In). At first, cobalt acetyl acetonate (Co(C₅H₇O₂)₃), acetyl acetonate (Fe(C₅H₇O₂)₃) and aluminum acetyl acetonate were charged to the bubblers 16, 17 and 18 heated to 150°C respectively. Bubbling argon gas 19 was caused to flow at 80 cc/min, 120 cc/min and 4 cc/min respectively, and these vapors were introduced by way of the rotary pump 21 onto the aluminum substrate 15 in the reaction chamber 11 at a reduced state. Then, oxygen (O₂) 20 as another reaction gas was caused to flow at a flow rate of 200 cc/min also on the aluminum substarte to cause reaction for about 25 minutes. The gas pressure was 1.1 x 10⁻² Torr and the high frequency power (13.56 MHz) was 500 W (5 W/cm²). The magnetic force of the magnet for magnetron discharge was about 500 gauss near the substrate. The thickness of the cobalt ferrite film deposited on the substrate was 2250 Å. Then, X-ray analysis for the crystal structure and the measurement of the Kerr rotating angle (by entering laser beams at wavelength of 780 nm onto the ferrite film, reflecting at the aluminum surface and detecting the laser beams permeated through the ferrite film again for measurement) were carried out. The results are shown in Table 5 as Sample No. 1. In the same manner, the results of the X-ray analysis and the Kerr effect (magnitude of the Kerr rotation angle) were measured while varying the substrate temperature, type of the chelate, amount of bubbler (Ar flow rate), pressure in the reaction chamber (by varying the valve operation to the rotary pump), method of generating plasmas, etc. are shown in Table 5 as Sample Nos. 2 - 24. Sample Nos. 25, 26 are Comparative Examples other than this invention. The X-ray analysis was carried out for examining the crystal structure and the orientation of the film of the cobalt ferrite, as well as the solid solubilized state of the additives M (where M represents one of Al, Cr, Fe, Gd, Mn and In). The Kerr effect (magnitude of the Kerr rotation angle) was examined by a polarized plane modifying method (for instance, as disclosed by Imamura, the Journal of the Institute of Television Engineers of Japan, Vol. 39, No. 4, 1985, 366p). Further it was also examined by the magnetic property (B-H curve) of the film due to VSM (vibration sample type magnetic force meter) whether the cobalt ferrite film was perpendicular magnetization film or not. Example 6 In the same manner as in Example 5, ferrocene (Fe(C₅H₅)₂), manganese acetylacetonate (Mn(C₅H₇O₂)₃) and zinc acetylacetonate (Zn(C₅H₇O₂)₂) were charged in the bubblers heated to 150°C. Bubbling argon gas 19 was caused to flow at 80 cc/min, 120 cc/min and 5 cc/min, and these vapors were introduced by a rotary pump onto a polyimide substrate in a reaction chamber at a reduced pressure. Then, oxygen (O₂) 20 as another reaction gas was caused to flow at a flow rate of 200 cc/min also on the polyimide substrate to react for about 20 min. The gas pressure was 1.0 x 10⁻² Torr, the substrate temperature was about 40°C and the high frequency power (13.56 MHz) was 500 W (5 W/cm²). The thickness of the manganese zinc ferrite in a columnar structure deposited on the substrate was 1.2 µm. As the result of the measurement for the magnetic properties of the film, the magnetic retentiveness was 5.0 Oe and the saturation magnetization was 380 emu/cc. The results are shown in Table 6 as Sample No. 1. The deposition temperature, magnetic retentiveness and the saturation magnetization of the ferrite film were measured while varying the pressure in the reaction chamber and the method of generating plasmas and the results are shown in Table 6 as Sample Nos. 2 - 4. As described above in Examples 1 - 6, thin films of magnetic oxide materials prepared by the plasma CVD process have such a structure as shown in Figure 2 where columns of a cylindrical cross sectional structure are orderly arranged on the organic film, that is, a so-called columnar structure. Such a film structure has a shape readily magnetizable in the direction perpendicular to the plane of the film and difficult to be magnetizable in the direction in parallel with the film plasma, thus, forming a perpendicular magnetization film due to so-called shape anisotropy, which is best suited to the magnetic recording medium at high density.

Claims: A method of manufacturing a magnetic thin film by deposition on a substrate from a mixture of a metallic compound and oxygen, while heating the substrate at a low temperature below 350°C or without heating the substrate, thereby depositing a thin film of magnetic oxide on the substrate, characterised by: decomposing a gas of an organic metallic compound containing elements constituting a magnetic material and oxygen as a reaction gas in high frequency plasmas, magnetron discharge plasmas or electron cyclotron plasmas under a low pressure from 1.3 x 10³ to 1.3 x 10⁻² Pa (10 to 10⁻⁴ torr). A method according to claim 1, wherein the organic metallic compound comprises barium and iron alkoxides. A method according to claim 1, wherein the organic metallic compound comprises triethoxy iron (Fe(O C₂H₅)₃), diethoxy barium (Ba (O C₂H₅)₂), triethoxy cobalt (Co(O C₂H₅)₃) and diethoxy zinc (Zn(O C₂H₅)₂) or iron acetylacetonate (Fe(C₅H₇O₂)₃), cobalt acetylacetonate (Co(C₅H₇O₂)₃), barium acetylacetonate (Ba(C₅H₇O₂)₂), and zinc acetylacetonate (Zn(C₅H₇O₂)₂). A method according to claim 1, wherein the organic metallic compound comprises strontium and iron alkoxides. A method according to claim 4, wherein (Sr(OR)₂ where R represents an alkyl group is used as the alkoxide compound containing strontium. A method according to claim 4, wherein (Fe(OR)₃ where R represents an alkyl group is used as the alkoxide compound containing iron. A method according to claim 1, wherein the organic metallic compound comprises a cobalt-containing chelate, iron-containing chelate and M-containing chelate (where M represents one of Al, Cr, Gd, Mn and In). A method according to claim 7, wherein the cobalt -containing chelate is acetylacetonate. A method according to claim 7, wherein the iron-containing chelate is iron acetylacetonate. A method according to claim 7, wherein the M-containing chelate where M represents one of Al, Cr, Gd, Mn, In comprises Al acetylacetonnate (Al(C₅H₇O₂)₃), Cr acetylacetonate (Cr(C₅H₇O₂)₃), Gd acetylacetonate (Gd(C₅H₇O₂)₃), Mn acetylacetonate (Mn(C₅H₇O₂)₃) and In acetylacetone (In(C₅H₇O₂)₃). A method according to claim 1, wherein the organic metallic compound comprises ferrocene (Fe(c₅H₅)₂), manganese acetylacetonate (Mn(C₅H₇O₂)₃) and zinc acetylacetonate: (Zn(C₅H₇O₂)₂). A thin film of magnetic oxide formed on a substrate by deposition on the substrate from a mixture of a metallic compound and oxygen while heating the substrate at a low temperature below 350°C or without heating the substrate, thereby depositing a thin film of magnetic oxide on the substrate, characterised by being obtainable by decomposing a gas of an organic metallic compound containing elements constituting a magnetic material and oxygen as a reaction gas in high frequency plasmas, magnetron discharge plasmas or electron cyclotron plasmas under a low pressure from 1.3 x 10³ to 1.3 x 10⁻² Pa (10 to 10⁻⁴ Torr) while heating a substrate at a low temperature below 350°C or without heating the substrate, thereby depositing a thin film of magnetic oxide on the substrate. A thin film according to claim 12, wherein the organic metallic compound comprises barium and iron alkoxide. A thin film according to claim 12, wherein the organic metallic compound comprises triethoxy iron (Fe(O C₂H₅)₃), diethoxy barium (Ba(O C₂H₅)₂) triethoxy cobalt (Co(O C₂H₅)₃) and dithoxy zinc (Zn(O C₂H₅)₂) or iron acetylacetonate (Fe(C₅H₇O₂)₃), cobalt acetylacetonate (Co(C₅H₇O₂)₃), barium acetylacetonate (Ba(C₅H₇O₂)₂) and zinc acetyl acetone (Zn(C₅H₇O₂)₂. A thin film according to claim 12, wherein the organic metallic compound comprises strontium and iron alkoxide. A thin film according to claim 15, wherein (Sr(OR)₂ where R represents an alkyl group is used as the alkoxide compound containing strontium. A thin film according to claim 15, wherein Fe(OR)₃ where R represents an alkyl group is used as the alkoxide compound containing iron. A thin film according to claim 12, wherein the organic metallic compound comprises a cobalt-containing chelate, iron-containing chelate and M-containing chelate (where M represents one of Al, Cr, Gd, Mn and In). A thin film according to claim 18, wherein the cobalt-containing chelate comprises cobalt acetylacetonate. A thin film according to claim 18, wherein the iron-containing chelate comprises iron acetylacetonate. A thin film according to claim 18, wherein the M-containing chelate where M represents one of Al, Cr, Gd, Mn, In comprises Al acetylacetonate (Al(C₅H₇O₂)₃), Cr acetylacetonate (Cr(C₅H₇O₂)₃), Gd acetylacetonate (Gd(C₅H₇O₂)₃), Mn acetylacetonate (Mn(C₅H₇O₂)₃) and In acetylacetonate (In(C₅H₇O₂)₃). A thin film according to claim 12, wherein the organic metallic compound comprises ferrocene (Fe(C₅H₅)₂, manganese acetylacetonate (Mn (C₅H₇O₂)₃) and zinc acetylacetonate (Zn(C₅H₇O₂)₂).

Inventors: AOKI, MASAKI, OKINAKA, HIDEYUKI, SAKAI, MASAYUKI, TORII, HIDEO
Applicants: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1986
Main classification: H01F41
IPC codes: H01F41, G11B5, H01F10