WO2002033715A1

WO2002033715A1 - Magnetic thin film production method and apparatus, and magnetic thin film

Info

Publication number: WO2002033715A1
Application number: PCT/JP2001/009187
Authority: WO
Inventors: Migaku Takahashi; David Djayaprawira; Hiroki Shoji
Original assignee: Migaku Takahashi; David Djayaprawira; Hiroki Shoji
Priority date: 2000-10-20
Filing date: 2001-10-19
Publication date: 2002-04-25
Also published as: AU2002210912A1; TW518577B

Abstract

A method for producing a magnetic thin film by which an iron carbide or iron carbide-cobalt film the main phase of which is an a'-phase is formed stably without being influenced by the temperature of the deposit surface where the thin film is to be formed, an apparatus for producing a magnetic film wherein a desired plasma condition of the surface of a substrate where an iron carbide or iron carbide-cobalt film the main phase of which is an a'-phase is deposited can be set, and a magnetic thin film having a high saturation magnetization, a low coercive force, and a high temperature resistance are disclosed. The method is characterized by comprising step A of producing a plasma little damaging the deposits urface of the substrate over the substrate placed in a reduced-pressure space by using a process gas and forming an iron carbideo r iron carbide-cobalt film the main phase of which is an a'-phase and composed of constituent elements including at least carbona nd iron or carbon, iron, and cobalt on the substrate by using the plasma and a material source of the magnetic film. The magnetic thin film formed by the production method and apparatus is preferably used to produce a magnetic pole material of a magnetic head for recording a magnetism signal on a medium such as a hard disk, a floppy disk, or a magnetic tape.

Description

Description Method and apparatus for manufacturing a magnetic thin film, and magnetic thin film

The present invention relates to a method and an apparatus for manufacturing a magnetic thin film, and a magnetic thin film. More specifically, when producing an iron carbide film or an iron cobalt film using plasma, it is stable so that the iron carbide film or the iron cobalt film forms a main phase comprising a single phase. TECHNICAL FIELD The present invention relates to a method and an apparatus for manufacturing a magnetic thin film that can be formed by using a magnetic thin film.

The magnetic thin film manufactured by using the manufacturing method and the manufacturing apparatus according to the present invention is suitably used when manufacturing a magnetic pole material of a magnetic head for recording a magnetic signal on a disk, a floppy disk, a magnetic tape, or the like. This application is based on a patent application to Japan (Japanese Patent Application No. 2001-3211748), and the contents of the Japanese application are incorporated herein by reference. I do. 2. Description of the Related Art In recent years, with the advancement of advanced information, the need for devices for storing such information, especially small and large-capacity storage devices, has been increasing. In response to this, for example, in the case of hard disk drives (HDDs), research institutes are keenly developing technologies to improve the recording density per unit area of the magnetic recording media to be mounted.

In order to achieve the higher recording density, a medium with a high coercive force that enables stable existence of minute magnetic domains written on the recording layer of the medium, and such minute magnetic domains are incorporated into the medium There is a need for the development of a recording head capable of performing such operations and a reproducing head capable of detecting leakage magnetic fields from these minute magnetic domains with high sensitivity. Conventional magnetic heads consist of a single element that has both recording and reproducing functions.However, as the size of the medium has been reduced due to the downsizing of the device and the linear velocity in the magnetization reversal direction has decreased, the linear A reproduction head composed of a magnetoresistive (MR) element utilizing a magnetoresistive effect that can detect a stray magnetic field stably with high sensitivity regardless of speed is being installed as a standard. In other words, current magnetic heads have a configuration in which a write-only recording head and a read-only reproduction head are combined.

As is evident from these technological trends, future recording heads will require pole materials with high saturation magnetization, which can generate strong magnetic fields, in order to record signals by sufficiently magnetizing a medium with high coercivity. . As the magnetic pole material that has been favorably used up to now, Pamalloy (78 w to / o Ni—Fe alloy) having a saturation magnetization of about 1 Tesla (T) is famous. After that, as materials with improved saturation magnetization, Sendust (Fe-A1-S 〖alloy) with a saturation magnetization of about 1.1 to 1.2 T and C with a saturation magnetization of about 1.5 T o-based amorphous materials have been developed. More recently, the following material systems have received attention.

(1) Japanese Patent Application Laid-Open Publication No. H11-07412 (hereinafter referred to as Reference 1) discloses a method for producing a Co—Fe—Ni alloy film using a plating method. The cobalt content is 40 to 70 wt% (weight./.), The iron content is 20 to 40 wt%, and the nickel content is 10 to 20 wt. /. And a Co—Fe—Ni alloy having a crystal structure of a body-centered cubic γ phase and a face-centered cubic α phase can be produced. The obtained alloy film has a coercive force and magnetostriction. Is small and has a saturation magnetization of more than 2 T. Furthermore, it is described that post-heating treatment at 100 ° C. or more is effective for improving corrosion resistance.

(2) Japanese Patent Application Laid-Open Publication No. 08-170730 (referred to as Reference 2) discloses a method for producing an alloy film mainly composed of Fe or Co using a sputtering method. However, Fe or Co is used as a material for a magnetic film that exhibits soft magnetic properties by performing heat treatment. And at least one selected from Ta, Zr, Hί and Nb in the concentration range of 5 to 20 at% (atomic%). It is composed of an alloy containing at least one element selected from the group in a concentration range of 5 to 20 at%, and in this magnetic film, A 1, T i, Cr, Ru, It describes that at least one element selected from Rh, Pt, Pd, Mo, and W is added at a concentration of 1 to 20 at ° / ₀ . The obtained alloy film has a saturation magnetization of 1.5 T, a coercive force of 0.1 Oe, a magnetic permeability at 1 MHz of 30000 or more, and a magnetostriction constant of 10 to ¹⁷ units. It is described as having good soft magnetic properties.

(3) Sugita et al. Reported the following about the preparation of a single-crystal Fe _e N ₂ film using the MBE (Molecular beam epitaxy) method [Y. Sugita et. Al., J. Appl. Phys. 76, 6637 (1994), referred to as Reference 3]. As the substrate, In was obtained by making the length of the a-axis and the lattice constant of the Fe ₁₆ N ₂ film substantially coincide with each other. , Using _{_{2 G a 0. S A s (}} 0 0 1) of special substrates. First, after heating this substrate in a vacuum (675 ° C, 5 minutes), iron as an evaporation source was blown by electron beams on the substrate at a temperature of 200 ° C in a nitrogen atmosphere. Then, an iron nitride film containing about 11 at% of nitrogen is manufactured. At that time, it is important to set the film forming speed to 0.002 to 0.003 nm / sec and the gas pressure during the film forming to 0.1 to 0.2 mTorr. The obtained iron nitride film was a martensite (α ') film, and its saturation magnetization was about 2.4%. Then, 2 0 0 true air of 1 0- ⁸ Torr table after the film formation. The even and ί亍Uko between come C heat treatment called Aniringu handle 9 0 days, a saturation magnetization of about 2.9 monocrystalline _{_{F e 1 6 N 2 (a}} ") of Τ film it is described that can be obtained However, the above-described related art has the following problems.

(1) The technology shown in Document 1 is to produce the recording head magnetic pole material by a wet process called the plating method. On the other hand, it is difficult to fabricate the MR element, which constitutes the reproducing head that is mounted at the same time, by the plating method. Therefore, avoid double investment and build an inexpensive manufacturing process, or stabilize interface management across two processes (such as avoiding contamination and maintaining flatness). From the standpoint of manufacturing, it is in a situation where it is desired to refrain from using magnetic pole materials by plating.

(2) In the technique disclosed in Reference 1, when providing a plating layer made of the above-described material forming a magnetic pole, it is necessary to form a base plating layer on the insulating layer by a sputtering method. This step is indispensable for the magnetic pole material according to Document 1 to satisfy the desired characteristics.However, the head structure is merely an unnecessary part or an unnecessary interface addition, and the film caused by the interface peels.ゃ It can be a source of distortion.

(3) For the magnetic pole material of Reference 1, the corrosion resistance after film formation is uneasy, and it is judged that post-heat treatment or addition of a protective film of 10 ° C or more is essential. This suggests that it is necessary to consider countermeasures when applying the magnetic pole material of Reference 1 to products.

磁 With the magnetic pole material of Reference 2, a recording head can be manufactured by the same sputtering method as the MR element that constitutes the reproducing head, so it can be evaluated in promoting the all-dry process of the magnetic head. Meanwhile, the obtained saturation magnetization is about 1.5 T, and the information is transferred to a medium whose coercive force used to increase the recording density in the future exceeds 250 Elsted (O e). I have to say that it is powerless to write.

磁 The magnetic pole material in Reference 2 must be at least a quaternary system, and the examples show a quinary system. From this, it is feared that the margin of the composition ratio at which good saturation magnetization can be obtained is narrow, and strict film composition control is required.

磁 In the magnetic pole material of Reference 2, it is necessary to control the crystal grain size in order to obtain desired magnetic properties, and heat treatment after film formation is essential for this. For example, 50 after the crystallization temperature after film formation. It is described that heat treatment is performed at a low C of 49 ° C. for 3 hours, and then at 590 ° C. for 30 minutes. In the case where a recording head is formed after the reproduction head is manufactured, this heat treatment causes disturbance at the interface of the MR element composed of a laminate of ultra-thin layers constituting the reproduction head, and consequently reduces the characteristics of the MR element. This is a difficult process to adopt because it can cause deterioration.

磁性 The magnetic film of Ref. 3 has the largest saturation magnetization of 2.9 T reported so far, and has the feature that it can be manufactured by the MBE method which is one of the dry processes. However However, a magnetic film having desired characteristics can be obtained only on a special substrate surface, and its film formation rate is extremely low, from 0.002 to 0.003 nmsec, and is used in mass production. Due to difficult production conditions, it was not adopted in the actual magnetic head manufacturing process. For the above-mentioned reasons, in the manufacturing process of the separation type magnetic head for recording and reproduction, development of a recording head magnetic pole material satisfying the following conditions at the same time and a method of manufacturing the same are expected.

(A) A magnetic pole material having a saturation magnetization of 1.5 T or more, preferably 2 T or more.

(B) A magnetic pole material having a coercive force of 2 Oe or less, preferably 1 Oe or less.

(C) Magnetic pole materials and manufacturing methods that can be manufactured by the same dry process as manufacturing MR elements for read heads for the purpose of maintaining impurities and maintaining interface flatness.

(D) A manufacturing method that has a film forming rate adapted to the mass production process, that is, has the ability to adapt to the manufacturing process, and enables the construction of an inexpensive manufacturing line.

(E) A magnetic pole that can be formed at a low temperature of 100 ° C or less so as not to affect the interface of the previously manufactured thin film laminate, for example, the MR element, and that does not require heat treatment after film formation. Material and recipe.

Recently, in the above-described separation type magnetic head manufacturing process, a post-heating treatment of about 300 ° C. is performed for the purpose of improving the magnetic characteristics of the MR element which is a thin film laminate manufactured earlier. Therefore, it is also desired to develop a magnetic pole material and a manufacturing method that can secure the magnetic properties shown in (A) and (B) above even after such post-heating treatment. A report that satisfies these multiple conditions is the report of Kim and Takahashi of 1972 [TK Kim and M. Takahashi, Appl. Phys. Lett. 20, 492 (1972)]. The highlight of this report is that it uses a very simple thin film formation method called evaporation, which is one of the dry processes, and has a very low coercivity and extremely high 2.58 T on a substrate at almost room temperature. That is, an iron nitride film having a saturation magnetization was produced at a deposition rate that enables mass production. However, since then, many laboratories have conducted additional tests, A magnetic film having the above characteristics cannot be obtained stably, and can only be produced under special conditions as described in Reference 3.

Therefore, a magnetic pole material for a recording head satisfying the conditions described in the above (A) to (E) and a method for manufacturing the same are now strongly demanded. In order to respond to this demand, the present inventors have filed Japanese Patent Application No. 2000-166382 (filed on May 31, 2000) with a saturation magnetization of 2 T or more and a coercive force of 2〇. As a magnetic thin film having soft magnetic properties of e (l O e = approximately 79 A / m) or less, an iron carbide film consisting of a single phase of at least carbon and iron as a constituent element is promising. Was. The patent application describes that the iron carbide film composed of the α′-phase single phase can be stably obtained by setting the substrate temperature at the time of film formation within a predetermined range. The application also discloses that an iron-cobalt film obtained by adding cobalt as a third element to the iron carbide film can obtain a higher saturation magnetization.

However, in general, the temperature of the substrate needs to be fine-tuned depending on the material constituting the substrate or the laminate provided in advance on the substrate and the difference in the surface shape of the laminate. When the above-mentioned iron carbide film is provided as a single layer, the base condition of the iron carbide film is not always made of the same material and shape. Therefore, regardless of the material and shape of the substrate surface on which the iron carbide film and the iron cobalt film are deposited, a production process in which an iron carbide large iron cobalt carbide film having a main phase is always stably obtained. As a result of studying the method and the manufacturing apparatus, the present invention was reached. DISCLOSURE OF THE INVENTION A first object of the present invention is to provide a magnetic thin film in which an iron carbide film or an iron cobalt carbide film having an α 'phase as a main phase is stably obtained without being affected by the temperature of the deposition surface on which the thin film is provided. To provide a manufacturing method.

A second object of the present invention is to produce a magnetic thin film capable of setting the surface of a substrate on which an iron carbide film or an iron cobalt film having an a ′ phase as a main phase is deposited under desired plasma conditions. Manufacturing apparatus.

A third object of the present invention is to provide a magnetic thin film having a soft magnetization characteristic of a saturation magnetization of 2 T or more, a coercive force of 20 e or less, and a heat resistance of 300 ° C. or more. And there. The method for producing a magnetic thin film according to the present invention includes the steps of: using a process gas to generate plasma with small plasma damage to a deposition surface of the substrate on a substrate disposed in a reduced-pressure space; A base material source for use in forming an iron carbide film or an iron cobalt carbide film having at least carbon and iron or carbon, iron and cobalt as constituent elements and a main phase as the main phase on the substrate. Forming step Α. An apparatus for producing a magnetic thin film according to the present invention is characterized in that a process gas is used to generate a plasma having a small plasma damage applied to a deposition surface of the substrate on a substrate disposed in a reduced-pressure space, and the plasma and the magnetic thin film are generated. Utilizing a base material source for the formation of carbon, an iron carbide film or carbonized material having at least carbon and iron or carbon, iron and cobalt as constituent elements and an α ′ phase as a main phase on the substrate. A manufacturing apparatus for forming an iron-cobalt film, comprising: a plasma generating unit for forming the iron carbide film or the iron-cobalt carbide film; and a substrate holding unit capable of moving the substrate along a direction in which the plasma concentration gradient is generated. It is characterized by having. The magnetic thin film according to the present invention is an iron-cobalt film having an α ′ phase as a main phase and at least carbon, iron and cobalt as constituent elements, and having a cobalt content of 12 to 50 in atomic%. It is characterized by being. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the relationship between the substrate temperature when producing a magnetic thin film according to the present invention and the crystal morphology of the produced magnetic thin film, that is, the X-ray intensity of the (02) plane. . FIG. 2 is a schematic cross-sectional view showing an example of the magnetic thin film according to the present invention, wherein (a) shows a case of a single layer, and (b) shows a case of a multilayer.

FIG. 3 is a graph showing an X-ray analysis result when the magnetic thin film according to the present invention is an iron carbide film, wherein (a) shows a diffraction pattern mainly from a (002) plane of the magnetic thin film. (B) shows the case where only the diffraction line from the (002) plane of the magnetic thin film is observed.

Fig. 4 is a graph showing the results of X-ray analysis of the various samples prepared. (A) is the result of sample SF and sample S1, (b) is the Fe-C alloy target used for film formation. 7 is a graph showing the results of samples prepared by changing the carbon content of the samples.

Fig. 5 shows the results of X-ray analysis of the sample prepared by changing the electron density of the plasma: Ne. Fig. 6 shows the graph showing the results of X-ray analysis of the sample prepared by changing the electron temperature of the plasma: Te. It is.

FIG. 7 is a schematic cross-sectional view illustrating an example of a magnetic thin film manufacturing apparatus according to the present invention. FIG. 8 is a schematic cross-sectional view illustrating another example of a magnetic thin film manufacturing apparatus according to the present invention. .

FIG. 9 is a graph showing an X-ray analysis result when the magnetic thin film according to the present invention is an iron cobalt carbide film.

Figure 10 plots the lattice constants a and c of the iron carbide cobalt film measured by the Schulz reflection method and the axial ratio c / a obtained from these values against the carbon content in the film. The carbon content is 6 at. /. (A) is the direction of the bct structure in the <001> direction, (b) is the direction of the Lct <b> 0 in the bct structure, and (c) is the hysteresis curve of the iron carbide cobalt film in the bct structure. The results in the <110> direction are shown.

FIG. 12 is a graph showing the relationship between the content of konole and the saturation magnetization Ms in the iron carbide cobalt film according to the present invention.

FIG. 13 is a graph showing an example of a result of examining a temperature change (M s−τ curve) of saturation magnetization in the iron carbide cobalt film according to the present invention. FIG. 14 is a graph showing another example of the result of investigating the temperature change (M s−τ curve) of the saturation magnetization in the iron-cobalt carbide film according to the present invention.

FIG. 15 is a graph showing the relationship between the cobalt content and the decomposition temperature Τρ · d. In the iron-cobalt carbide film according to the present invention.

FIG. 16 is a graph showing the relationship between the carbon content and the coercive force He in the iron-cobalt carbide film according to the present invention.

FIG. 17 is a graph showing the results of X-ray analysis before and after heat treatment of the iron-cobalt carbide film according to the present invention.

10 substrate,

1 1 Iron carbide film (magnetic layer)

1 1 'iron cobalt carbide film (magnetic layer)

70 1 a, 70 1 b, 70 1 c, 70 1 d substrate,

700 sputter chamber,

70 1 a, 70 1 b, 70 1 c, 70 1 d substrate,

70 2a substrate holder,

70 3a substrate holding means,

704 substrate moving means,

705 First deposition chamber,

706 Second deposition chamber,

707 a, 70 7 b shirt

708a, 708b protection plate,

70 9a, 70 9b primary target,

7 10 a, 7 10 b, 7 10 c, 7 10 d magnet,

7 1 1a, 7 1 1b Second target,

7 1 2 a, 7 1 2 b, 7 1 2 c, 7 1 2 d magnet,

7 1 3 AC power supply,

7 14, 7 1 5 DC power supply,

7 16 a, 7 16 b, 7 17 a, 7 17 b force sword, 800 film forming chamber,

8 0 1 Substrate,

80 2 substrate holder,

8 0 3 substrate holding means,

8 0 4 Shutter,

8 0 5 Fe-C base material,

8 0 6 ion gun,

8 0 7 filament,

8 0 8 grid,

8 0 9, 8 1 0 DC power supply,

8 1 1 Process gas inlet,

8 1 3 Magnetic field application means. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The method for producing a magnetic thin film according to the present invention is characterized in that the crystal structure of the magnetic thin film is mainly composed of a martensite (α ′) phase by an X-ray diffraction method using (Co-Κα) or (Cu-K) as a radiation source. This is a method for producing an iron carbide film or an iron cobalt film, which is confirmed to be as follows. For example, as shown in FIG. 2 (a), a substrate 10 placed in a reduced pressure space of the order of 10 to ⁷ Torr is used. A plasma having a small plasma damage applied to the deposition surface of the substrate 10 is generated by using a process gas composed of Ar gas or the like, and the plasma and a base material source for forming a magnetic thin film are used. A step A of forming at least carbon and iron or carbon, iron and cobalt as constituent elements on the substrate 10 and forming an iron carbide film 11 or an iron cobalt cobalt film I having an α ′ phase as a main phase. .

As the radiation source used in the X-ray diffraction method having the above configuration, Cr, Fe, Cu, Mo, W, or the like may be used instead of Co.

In addition, even if an electron diffraction method is used instead of the X-ray diffraction method, it is possible to detect an iron carbide film or an iron cobalt film having a martensite (α ′) phase as a main phase. You. Specifically, convergent-beam electron diffraction is a preferred technique. When this convergent electron diffraction is used, a diffraction disk is observed instead of diffraction spots due to a large convergence angle of the electron beam irradiating the sample. This method produces diffraction patterns with angular resolution that cannot be obtained with other electron diffraction methods (eg, high-resolution electron diffraction). By analyzing the shuus focused electron diffraction pattern, it is possible to identify the sample thickness, lattice constant, crystal symmetry (point group-space group), and lattice defects. In this analysis, the limited area required for electron beam irradiation is smaller than 1 Οηπιφ. Therefore, even if the above magnetic thin film is used as a magnetic pole material such as a magnetic head or the like, since the thickness is 50 nm to 500 nm, it is possible to sufficiently analyze the structure of the film.

In the above configuration, as shown in FIG. 3, the iron carbide film 11 having the α ′ phase as the main phase is, as shown in FIG. 3, a diffraction line from the (002) plane of the α ′ phase, that is, α ′ (00 2 ) Are identified mainly by observation. In Fig. 3, (a) shows the case where the diffraction line from the (002) plane of the iron carbide film forms the main peak, and a broad shoulder is observed on the high angle side, and (b) shows the case where the iron carbide film has a broad shoulder. In this case, only diffraction lines from the (002) plane are observed. In other words, as apparent from FIG. 3 (a), the iron carbide film 11 having the α ′ phase as the main phase according to the present invention has a diffraction line from the (002) plane of the α ′ phase and other diffraction lines. In other words, it consists of a broad shoulder (oblique line) observed on the high angle side.

When the other diffraction lines disappear and a single phase is formed, the iron carbide film 11 is composed of only the _α ′ phase single phase, and the α, phase ( 00 2) Only diffraction lines from the plane are observed.

The diffraction line from the (00 2) plane of this α 'phase is 70 at 2Θ. ~ 7 7. It can be obtained with a power of 0. ~ 1 1 5. No diffraction line stronger than α '(002) is observed in the range. Therefore, the iron carbide film 11 according to the present invention can easily determine whether or not it has a desired crystal morphology at the time of manufacture, so that the film quality can be accurately determined even after the film formation as well as during the film formation. It has the feature that it can be manufactured while grasping it. In addition, the iron carbide film 11 having the α 'phase as a main phase described above has a saturation magnetization (Ms) of 2 mm or more and a coercive force (2 Oe or less) of 2 Oe or less without a heating treatment after the film formation. coercive force) It has good soft magnetic characteristics with Hc.

In particular, since the method for producing a magnetic thin film according to the present invention includes the step A having the above configuration, as shown in FIG. 1, the produced magnetic thin film composed of the iron carbide film 11 is extremely flat. It can have a surface morphology. In other words, instead of a plasma with a large plasma damage to the deposition surface of the substrate 10 (electron density of the plasma Ne = 7 × 10 ¹⁰ cm "3, 1 ^× ^{10 10} cm- ³ ), the plasma damage is small. plasma ^{(Ne = 2 X 1 0 9} cm ~ \ 7 X 1 0 8 cm "3) Thus in fabricating a magnetic thin film 1 1 using, 0. I nm surface roughness R a of the magnetic thin film 1 1 (1 A) Since the value can be suppressed to a smaller value, the flattening of the film surface can be remarkably promoted. shown that iron carbide film 1 1, main phase can be stably obtained, the strength of 80% or more resulting substrate temperature in the range of the maximum value, for example, the Ne = 7 X cm ³ of (00 2) If while in (dotted line) is about 5 ° C~6 0 ° C, in the case of ^{^{Ne = 2 XI 0 9 cm 3}} ( dashed line) since it becomes 0 ° C~1 3 0 ° C , Can expand significantly found.

Therefore, the manufacturing method of the present invention for producing a magnetic thin film made of the iron carbide film 11 using plasma having a small plasma damage achieves the flattening of the magnetic thin film 11 and a desired crystal form. The effect of expanding the temperature range of the substrate at the time of film formation to obtain an iron carbide film having the above is also provided.

In other words, according to the present invention, in order to produce an iron carbide film having a desired phase as a main phase, it is not necessary to restrict the temperature of the substrate so much to a certain range, so that the material constituting the substrate and its surface are not required. A process that is hardly bound by the shape and can stably and flexibly produce an iron carbide film having a desired α ′ phase as a main phase on a substrate or a thin film made of various materials and surface shapes can be provided. .

In other words, according to the method of manufacturing a magnetic thin film having the above-described configuration, the method was caused by the film forming temperature Due to the problem, that is, the temperature difference on the deposition surface of the magnetic thin film caused by the difference in the surface material and surface shape of the substrate on which the iron carbide film is deposited, the iron carbide film having the α ′ phase as the main phase stably The problem that the temperature range of the obtained substrate is narrow can be improved. Further, the fact that the substrate temperature at the time of film formation in which the iron carbide film having the α 'phase as the main phase is stably obtained is wider than before suggests that the conditions for manufacturing the iron carbide film according to the present invention are relaxed. As a result, the manufacturing margin is widened, which can contribute to cost reduction when mass production is performed.

Furthermore, under the conditions in which the iron carbide film having the above-mentioned main phase as a main phase can be obtained stably, the surface of the iron carbide film itself can be further flattened as compared with the prior art. When using as a magnetic pole material for a magnetic head for writing, it is necessary to provide a large number of laminated structures above and below this iron carbide film, but this iron carbide film gives a rough structure to the laminated structure located thereon. There is also an advantage that the influence due to the size can be significantly reduced. The effects of the above-described steps can be obtained more stably by focusing on the electron temperature T e and Ζ of the plasma or the electron density Ne of the plasma.

For example, as shown in FIG. 6, diffraction from by the electron temperature T e of the plasma which is occurs on a substrate than 4 X 10- ³ e V or 3 e V, the alpha 'phase (002) plane Since the intensity of the line, that is, α ′ (002), is 80% or more of the maximum value, a stable thin film can be formed. When the electron temperature Te of the plasma is set to 1 X 10 to ¹² eV or more and 1 eV or less, the intensity of α ′ (002) becomes 90% or more of the maximum value, and the desired magnetic characteristics are obtained. It is more preferable because the iron carbide film can be produced more stably.

On the other hand, even if the electron density Ne of the plasma generated on the substrate is 7 × 10 ⁸ cm— ³ or more and 2.5 × 10 ^{1 (5} cm— ³ or less), the diffraction line from the (002) plane of the α 'phase In other words, the intensity of α '(002) is 80% or more of the maximum value, so that a stable thin film can be formed, and the electron density Ne of the above plasma is 1 × 10 ⁹ cm— ³ or more. If it is less than 1 X 10 ¹ Qcm- ³ , the intensity of α '(002) will be 90% or more of the maximum value, so that an iron carbide film with desired magnetic properties can be manufactured more stably. It is more desirable because it can be done. Further, in the method for producing a magnetic thin film according to the present invention, the step of forming the iron carbide film or the iron cobalt film containing the single phase may include: And a step B of forming a thin film having an interatomic distance substantially equal to the interatomic distance of the iron carbide film or the iron cobalt film. Since the method for producing a magnetic thin film according to the present invention includes the above step B, it is possible to immediately deposit an iron carbide film or an iron cobalt film containing a single-phase single phase on the thin film immediately after film formation. Becomes Therefore, in the above step B, the opportunity of contaminating the interface between the thin film and the iron carbide film or the iron cobalt carbide film with impurities or the like can be eliminated, and the iron carbide film or the iron cobalt carbide film grows epitaxially on the thin film. Can be encouraged. Therefore, the manufacturing method including the above-described step B contributes to the production of a magnetic thin film capable of stably obtaining soft magnetic characteristics.

Furthermore, the method of manufacturing a magnetic thin film according to the present invention is characterized in that after the step A, a step C of heating the iron carbide film or the iron cobalt film is provided. Providing the step C for heating the magnetic thin film may make it possible to lower the coercive force of the magnetic thin film. This effect is particularly effective when the iron-cobalt carbide film has a predetermined carbon content, and lowers the coercive force of the magnetic thin film. As a film forming method suitable for performing the step of forming the iron carbide film having the α ′ phase as a main phase, for example, a facing target sputtering method or a plasma deposition method can be mentioned. Since the electron temperature T e and the electron density N e in the preferable ranges described above can be easily realized, the iron carbide film in which the strength of at least （(002) is at least 80% of the maximum value can be stably obtained. Can be formed.

In the iron carbide film prepared by using the plasma of the electron temperature T e and the electron density N e described above, the composition is made to be 0.5 at% or more and 15 a ΐ% or less of carbon and the balance of iron. In addition, a thin film having good soft magnetic properties with a saturation magnetization of 2 ° or more and a coercive force of 2 Oe or less can be more easily formed. In addition, this film composition should be 1 at% or more. When the content of carbon and the balance of iron are less than t%, the coercive force is further reduced: LO e is preferred.

Therefore, as a base material source for forming the magnetic thin film, for example, as a target, a carbon having a content of 0.5 at% or more and 15 at% or less and a balance of iron are used as long as the composition of the formed thin film and the target does not deviate. Alloy or composite material is more preferable, and an alloy or composite material composed of carbon of lat% or more and 12 at ° / o or less and the balance of iron is more preferable. Further, the iron carbide film according to the present invention may contain an appropriate amount of cobalt as the third element. In other words, the iron-cobalt film 11 1 ′ obtained by adding cobalt to the iron-carbide film 11 can further increase the saturation magnetization as shown in FIG. 12, and obtain a saturation magnetization exceeding 2.2 T. Therefore, a target made of a base material for forming the magnetic thin film may be made of carbon, iron and cobalt.

The iron cobalt film 11 ′ according to the present invention has a saturation magnetization (Ms) of 2 T or more even without performing a heat treatment after the film formation, similarly to the iron carbide film 11 described above. Figure 12]. Among them, the atomic content of cobalt. The iron carbide covanolate film 11 ′ with a ratio of 12 to 50 in / ₀ has a saturation magnetization of 2.2 T or more [Fig. 12] and has a crystal structure even after heat treatment at over 300 ° C. No significant change in the structure was observed [Fig. 15]. In particular, it can be seen that the iron-cobalt carbide film having a cobalt content of 30 to 42.5 atom ° / ₀ has a heat resistance exceeding 400 ° C.

In addition, the heat treatment in the step C causes a decrease in the coercive force He in the iron-cobalt carbide film 11 ′, as is apparent from FIG. In particular, the carbon content is 2 to 15 atoms. /. In the iron-cobalt carbide film 11 1 ′, the coercive force Hc after the heat treatment can be set to 2 Oe or less.

From the above results, the iron-cobalt film 11 ′ according to the present invention has sufficient resistance to the heat treatment at about 300 ° C. required in the manufacturing process of the MR element constituting the magnetic head. It became clear that there was. Therefore, the magnetic thin film made of the cobalt-containing iron-cobalt film having the cobalt contained therein 1) constitutes a magnetic head. It is mounted together with the MR element to be formed, and is extremely suitable as a magnetic pole material constituting a magnetic head for writing.

Further, as shown in Fig. 16, the iron cobalt film 11 'with a carbon content of 2 to 15 atom ° / ₀ has a coercive force after heat treatment of 2 Oe or less, and has excellent soft magnetic properties. Is more preferable because it can also have FIG. 9 is a graph showing an X-ray analysis result of the iron cobalt film 11 ′ according to the present invention. FIG. 9 shows that the iron cobalt film 11 ′ according to the present invention has a crystal structure mainly composed of the α ′ phase, similarly to the iron carbide film 11 (FIG. 3). FIG. 9 shows the case where only the diffraction line from the (002) plane of the magnetic thin film was successfully observed, and the result corresponds to the iron carbide film 11 in FIG. 3 (b). Although not shown here, also in the case of the iron carbide film 11 ′, the diffraction line forms a main peak as in the iron carbide film 11 in FIG. 3 (a), and a broad shoulder is observed on the high angle side. In some cases. Therefore, the iron-cobalt film 11 ′ having the α ′ phase as a main phase, as in the case of the iron-carbide film 11, can easily identify whether or not it has a desired crystal form at the time of manufacture. It is equipped with. In the iron-cobalt film (α′—Fe—Co—C film) 11 ′ according to the present invention, a hysteresis curve as shown in FIG. 11 is observed after the film formation. (A) is the result of the <001> direction of the bc7 structure, (b) is the result of the <100> direction of the bct structure, and (c) is the result of the <110> direction of the bct structure. A vibrating sample magnetometer (VS M) was used for this measurement. From Fig. 11 (a), it was confirmed that the c-axis of the iron-cobalt film 11 'was a hard magnetization axis, and that the c-plane was an easily magnetized surface from Figs. 11 (b) and (c). Wear. This suggests that it is possible to easily control the reversal of the direction of magnetization generated in the c-plane by applying a positive or negative external magnetic field having an appropriate strength in the c-plane of the iron-cobalt film. Therefore, the iron-cobalt carbide film according to the present invention is suitable as a magnetic pole of a recording head.

As described above, iron carbide having a cobalt content of 12 or more and 50 or less at atomic ° / ₀ is obtained. After the film is formed, α is obtained by X-ray diffraction or electron diffraction. '' Phase The diffraction peak from the (002) plane is observed as the main peak (Fig. 9). When such an iron-cobalt carbide film is subjected to a heat treatment at over 300 ° C after film formation, the main diffraction peak observed changes from the (002) plane of the α 'phase to the (200) plane of the a phase. It was confirmed that it would change (Figure 17). When 2Θ is in the range of 60 to 70 degrees, no diffraction peaks other than these peaks are observed.

In the iron-cobalt film 11 'according to the present invention, slight changes in crystallinity were observed before and after the heat treatment. However, the crystal structure, the axis of hard magnetization, and the surface of easy magnetization were hardly changed. The same hysteresis curve as in FIG. 11 was observed in the heat-treated iron-cobalt film. That is, the iron-cobalt carbide film according to the present invention has a body-centered square structure, does not depend on the presence or absence of a heat treatment performed after film formation, has a c-axis as a hard magnetization axis, a c-plane as an easy magnetization surface, The hard axis is substantially perpendicular to the film surface, and the easy magnetization surface is substantially horizontal to the film surface. Further, the iron-cobalt carbide film according to the present invention may incorporate nitrogen as the third element. When nitrogen is contained in appropriate amounts, more preferable because it reduces the magnetostriction of iron carbide cobalt film 10 one ^seven from 10 ^six.

Furthermore, the iron-cobalt carbide film according to the present invention includes a thin film having a lower layer in contact with the iron-cobalt carbide film and having an inter-atomic distance substantially equal to the inter-atomic distance of the iron-cobalt carbide film. The various magnetic characteristics described above can be obtained more stably. As an example of such a thin film, an iron film or an iron cobalt film having a (200) plane as a surface can be used. Further, in order to obtain more various magnetic properties of the iron-cobalt carbide film, it is preferable that the main element constituting the thin film has a lattice constant substantially equal to that of the iron-cobalt carbide film. By using a thin film composed of elements having substantially the same lattice constant as the iron-cobalt film as the lower layer of the iron-cobalt film according to the present invention, the iron-cobalt film deposited thereon can be very stably grown at the initial stage. Even if the film thickness increases, the occurrence of distortion and the like in the film is suppressed, so that higher crystallinity and film formation can be achieved, and iron carbide with stable various magnetic properties A cobalt film is obtained. Examples of the element whose lattice constant is substantially the same as that of the iron-cobalt film include one or more elements selected from Ag, Au, Pd, Pt, Rh, Al, Ir, and Ru. I can do it. The lattice constants of each element are Ag = 4.09 A (a-axis), Au = 4.08 A (a-axis), Pd = 3.89 A (a-axis), Pt = 3.92 A (a-axis), R h = 3.8 OA (a-axis), A l = 4.05 A (a-axis), Ir = 3.84 A (a-axis), Ru = 4.28 A ( c axis). Here, in the present invention, the lattice constant being substantially the same as that of the iron-cobalt film indicates a range of 4 A ± 10%. However, 1A = 0. Inm. The apparatus for manufacturing a magnetic thin film according to the present invention is characterized in that a process gas is used to generate a plasma with small plasma damage to a deposition surface of the substrate on a substrate disposed in a reduced-pressure space, thereby forming the plasma and the magnetic thin film. A base material source for use in forming an iron carbide film or iron carbide covanolate having at least carbon and iron or carbon, iron and cobalt as constituent elements and an α ′ phase as a main phase on the substrate. A manufacturing apparatus for forming a film, comprising: a plasma generating means for forming the iron carbide film or the iron cobalt film; and a substrate holding means capable of moving the substrate along a direction in which a concentration gradient of the plasma is generated. I have it.

According to this configuration, while the magnetic thin film provided on the substrate is being deposited, the surface of the film is exposed to the plasma generated by the plasma generating means, but the substrate is held by the substrate holding means. By appropriately moving along the direction in which the concentration gradient of the plasma is generated, while suppressing the damage to the deposition surface of the substrate from the plasma, the iron carbide film or the iron cobalt film having the desired phase as the main phase can be formed. The substrate can be placed at a position where it can be formed. Therefore, in the manufacturing apparatus having the above configuration, the iron carbide film is hardly damaged by plasma even at the start of the deposition, during the deposition, or even after the deposition. In particular, during deposition, the thickness of the magnetic thin film to be formed can be gradually increased in an atmosphere where the influence of plasma damage is extremely small, so that the surface of the formed magnetic thin film is suppressed as much as possible and Temperature rise can be suppressed. That is, the magnetic thin film manufactured by the manufacturing apparatus having the above configuration can have an extremely flat surface form. When the flattening is promoted in this manner, the substrate temperature during film formation in which an iron carbide film having a main phase as a main phase can be stably obtained can be set in a wider range. It is possible to provide a manufacturing apparatus having a wide temperature margin during manufacturing. According to the above configuration, damage to the deposition surface of the substrate from the plasma can be suppressed, so that the α ′ phase is the main phase irrespective of the material and shape of the surface of the substrate on which the iron carbide film is deposited. This contributes to the construction of a production line with high yield and high reliability, because the production equipment is capable of obtaining films in a very stable manner.

In addition, the functions and effects provided by the manufacturing apparatus having the above configuration can be similarly obtained in the above-described iron-cobalt carbide film which is a magnetic thin film in which cobalt is added to the iron carbide film. Substrate holding means in the above structure, either variably controlling the position of the base body so that the electron temperature T e of the plasma substrate is exposed becomes less 4 X 1 0- ³ e V or 3 e V, or substrate exposed the plasma electron density N e Ca 7 X 1 0 ⁸ cm- ³ or more 2. 5 X 1 0 by ^{1 Q} cm one ³ variably controlling the position of the base body so as to become less, primary phases phase Is obtained very stably. The functions and effects obtained when the electron temperature T e and the electron density N e of the plasma fall within the above range also apply to the above-described iron-cobalt carbide film, which is a magnetic thin film containing cobalt in the iron carbide film. . According to the opposed target sputtering method or the plasma deposition method, plasma having the electron temperature T e and the electron density N e in the above-described ranges can be easily generated and maintained. In addition, the plasma obtained by these two methods has a feature that the electron temperature T e and the electron density N e change gradually with distance, that is, have a gentle concentration gradient. By appropriately arranging the substrate in the plasma having the gentle concentration gradient, the surface of the substrate on which the magnetic thin film is to be deposited is exposed to a plasma having desired values of electron temperature Te and electron density Ne. Can be.

In particular, since the concentration gradient of the plasma is generated in a direction perpendicular to the surface of the substrate, the magnetic thin film is deposited as long as the substrate holding means on which the substrate is placed is moved linearly back and forth. The electron temperature T e and the electron density N e of the plasma to which the substrate surface is exposed can be universally controlled. However, for example, even if a normal bipolar plate type sputtering apparatus is used, if the electron temperature T e and the electron density N e of this plasma are made variable and devised so that these can be kept low, it is sufficient. Iron carbide film (α'-Fe-C film) or iron carbide covanolate film (α'-Fe-Co-C film), which can be obtained with a facing target sputtering system or plasma evaporation system described later. Can be formed.

Further, the apparatus for producing a magnetic thin film according to the present invention forms a lower layer in contact with the iron carbide film or the iron cobalt film in addition to the plasma generating means for forming the iron carbide film or the iron cobalt film described above. Plasma generating means may be provided for forming a thin film having an atomic distance substantially equal to the atomic distance of the iron carbide film or the iron cobalt film. By providing the plasma generating means for forming the thin film, a magnetic thin film made of an iron carbide film or an iron cobalt film can be immediately deposited on the thin film without contaminating the thin film surface. For example, since the surface of the thin film that forms an interface with the iron carbide film or the iron cobalt film is extremely unlikely to be contaminated with impurities, an iron carbide film or a cobalt cobalt film made of a single-phase single phase is formed on the thin film. It becomes easier to grow epitaxially. Therefore, the manufacturing apparatus provided with the plasma generating means for forming a thin film contributes to the magnetic thin film having stable soft magnetic characteristics.

Furthermore, the apparatus for manufacturing a magnetic thin film according to the present invention may include a heat treatment unit for heating the iron carbide film or the iron cobalt film. Heat treatment using this heat treatment means lowers the coercive force of the magnetic thin film. In particular, when the magnetic thin film is made of the iron-cobalt carbide film 11 'having a predetermined carbon content, a great effect can be obtained. As an apparatus for manufacturing a magnetic thin film satisfying the above-described configuration, for example, a facing target type DC sputtering apparatus shown in FIG. 5 or a plasma deposition apparatus shown in FIG. FIG. 7 is a schematic sectional view of the inside of the sputtering chamber as viewed from above, and FIG. 8 is a schematic sectional view of the inside of the film forming chamber as viewed from the side.

(Opposite target sputtering method)

The facing target type sputtering method according to the present invention is carried out by using, for example, a facing target type sputtering apparatus shown in FIG. In the apparatus of FIG. ⁷ , 700 is a sputtering chamber, 701a, 701b, 701c, 701d are substrates, 702a holds the substrate 7Ola and heats, cools, or maintains the substrate 7Ola at a constant temperature. 703a is a substrate holding means for moving the substrate 701a in the direction in which the plasma concentration gradient is generated, and 704 is a substrate holder 701a, 701b. , 70 1 c, 70 1 d The means for rotating and moving the substrate used to direct the surface toward each film forming chamber, and 705 is for forming an iron carbide film (hereinafter also referred to as α'-Fe-C film). The first film forming chamber, 706 is a second film forming film for forming an Fe film. J! Room, 707a, 707b are shirts, 708a, 708b are anti-adhesion plates, 709a, 709b are F e — First target made of G alloy, 7 10 a, 7 10 b, 7 10 c, 7 10 d are magnets, 7 1 a, 7 11 b are second targets made of F e, 7 1 2 a, 7 1 2 b, 7 1 2 c, 7 1 2 d are magnets, 7 1 3 is AC power supply, 7 14, 7 1 5 is a DC power supply, and 716a and 716b, 717a and 717b are cathodes. Although not shown in FIG. 7, vacuum evacuation means for depressurizing each deposition chamber is provided below the sputter chamber 700 (on the back side of the paper), and the substrate is taken out via a gate valve above (the front side of the paper). A load lock chamber is provided, and a vacuum evacuation means for reducing the pressure in the load lock chamber is also provided. Further, each of the film forming chambers is provided with gas supply means for introducing a desired process gas, for example, Ar gas or N ₂ gas therein. As shown in FIG. 7, the facing target type sputtering apparatus is characterized in that a pair of targets made of the same material are arranged facing each other in one chamber. In the first film forming chamber 705 for forming an a′-FeFeC film, for example, two plate-shaped first targets 709 a and 709 b having the same dimensions are arranged to face each other. The permanent magnets 710a and 710b are placed in the force sword 716a so that the plasma focusing magnetic field is applied perpendicularly to the first target 709a and 709b. , 7 10 d are respectively arranged in the force swords 7 16 b. When a process gas such as Ar gas is introduced into the first film forming chamber 705 and a voltage is applied to both cathodes 7 16 a, 7]. 6 b from a DC power supply 7! _ 4, both targets 709 a And 709b are emitted from the target and reflected by high-speed γ electrons (secondary electrons) accelerated by the cathode descending part Since this secondary electron acts as an electrode, this secondary electron is confined between the two targets, and the secondary electron impact on the substrate 71 a disposed outside between the first target 709 a and 709 b is suppressed. You. In addition, while reciprocating in space, the energy of the electrons in the plasma is increased, or the gas collides with the ambient gas to promote ionization of the gas, resulting in high-density plasma P 1 (mesh area in Fig. 7). That is, a desired thin film can be appropriately deposited on the substrate 701a without being directly exposed to the high-density plasma P1.

Therefore, the facing target type DC sputtering apparatus shown in FIG. 7 can reduce the rise in substrate temperature during film formation due to such features, and can be formed at a lower gas pressure than a general planar type magnetron sputtering apparatus. The advantage is that a membrane is possible. In the apparatus shown in FIG. 7, it is preferable that the inner wall of the sputtering chamber 700 for forming a film is subjected to electrolytic polishing and chromium oxidation passivation (CRP) treatment to reduce the amount of gas emitted from the inner wall. A load lock chamber (not shown) is provided in the sputter chamber 700 via an all-metal gate valve (not shown). When the substrate 701 is set, the sputter chamber 700 is opened to the atmosphere. Therefore, the degree of vacuum can be maintained.

By rotating the tomb body moving means 704 at the center of the sputtering chamber 700 shown in FIG. 7, the surface of the substrate 701 a was directed to the α′—Fe—C film (iron carbide film) film forming chamber 705 side. Thereafter, the shirt 707a, which spatially separates the plasma P1 and the base 701a from each other, is opened for a predetermined time, so that a desired thickness is formed on the base 701. An Fe—C film can be formed.

The plasma P1 generated by the configuration in Fig. 7 has a plasma concentration gradient from the center of the two targets 709a and 709b arranged opposite to the base 7Ola. However, the plasma concentration has a distribution near the center of the axis at a maximum, and the concentration decreases as approaching the substrate 701a. In this apparatus, the concentration of the plasma P1 is increased by using the substrate holding means 703a provided between the substrate holder 702a for holding the substrate 701a and the substrate moving means 704 of the substrate 701a. There is a gradient (The arrow c in Fig. 7 is provided

In the above, the first Fe—C film deposition chamber 705 has been described in detail as an example, but the other Fe deposition chamber 706, which is the other deposition chamber, is the same except that the target material is different. The mechanism is provided, and almost the same film formation processing is possible. That is, by setting the substrate at the position A or the position C using the rotation moving means 704, an α′—Fe—C film or a Fe film can be deposited on the substrate.

In the case where the substrate is set at the position A by using the rotating and moving means 704, for example, a process gas such as Ar is introduced into the first film forming chamber 705, and the substrate on which the substrate 701a is placed is placed. By applying a voltage from the AC power supply 7 13 to the honolech 70 2 a, it is also possible to dry-etch the substrate surface.

In the apparatus shown in FIG. 7, the target is circular and its diameter t1 is 90 °, the distance between targets t2 is 100 °, and the distance t3 between the target center and the base is 90 °. And However, the value of the distance t 3 is determined by the movement of the substrate 71 along the direction in which the concentration gradient of the plasma P 1 occurs using the substrate holding means 703 a (arrow α in FIG. 7). Increases or decreases.

Further, since the plasma converging magnetic field is applied perpendicularly to the target, a leakage magnetic field of about 30 Oe (O e) exists in the surface of the substrate at the surface of the substrate. At the time of film formation, the permanent magnet 710 or 712 was arranged so that the direction of the leakage magnetic field at the substrate surface position was the same even when the substrate 701a was rotated. The rotation of the base holder 702 and the opening and closing of the shirt 707a or 707b were controlled by a stepping motor (not shown) via a rotation introducing machine (not shown).

In the above description, the facing target type D.C. sputtering apparatus has been described in detail. However, the α'-Fe-C film according to the present invention is an alternating current (R.F.C.) instead of a direct current (D.C.). ) Can also be used.

'Evaporation method)

The plasma deposition method according to the present invention uses, for example, a plasma deposition apparatus shown in FIG. It is implemented by that. In the apparatus shown in FIG. 8, 800 is a film forming chamber, 800 is a substrate, 800

Reference numeral 2 denotes a substrate holder having a built-in temperature control means for holding the substrate 81 and having a function of heating, cooling, or maintaining the temperature of the substrate 800, and reference numeral 803 denotes a plasma concentration gradient. Substrate holding means for moving the substrate 81 along the direction, 80

4 is a shirt, 805 is a Fe-C base material, 806 is an ion gun that places the base material in a crucible and melts it with an electron beam, 807 is a filament placed above the ion gun, 8 0 8 is a grid arranged in the space between the filament and the substrate, 8 0

9, 810 are a DC power supply, 811 is a process gas inlet, 812 is an exhaust port of the film forming chamber which leads to a vacuum exhaust means (not shown) for reducing the pressure in the film forming chamber, and 813 is an exhaust port of the film forming chamber. This is a magnetic field applying means for applying a magnetic field which is parallel to the film-forming surface of the substrate and is in one direction.

In a plasma deposition apparatus as shown in FIG. 8, an ion gun 806 that disposes and dissolves a Fe—C base material 805 in one film forming chamber 800 faces a substrate 8001. In the space between them, the filament 807 connected to the DC power supply 809 and the DC power supply 810 are connected from the Fe-C base material 805 toward the base body 81 in the space between them. The grid 808 and the shirt 804 at the ground potential are arranged in this order. When forming a film on the substrate 800, a process gas such as an Ar gas is supplied into the decompressed film forming chamber 800 through a process gas inlet 811 to adjust the gas pressure to a predetermined value. After that, the Fe—C base material 805 is melted by using an electron beam emitted from the ion gun 806, and is evaporated into an upper space in the film forming chamber 800. Then, the evaporated substance first passes through the space of the high-density plasma P2 generated by the electrons emitted from the filament 807. Next, the evaporated substance passes through the mesh-shaped dalid 808, passes through the plasma P 2 ′ reaching from the dalid 808 to the vicinity of the base 801, and reaches the base 800. Is deposited. Here, in the space between the filament 807 and the base body 81, a mesh-like dalid 808 having a negative potential by being connected to the DC power supply 810 is provided, so that the grid 808 is provided. The plasma P 2 ′ passing through the substrate 8 and reaching the vicinity of the substrate 8 0 1 has a lower density than the plasma P 2 described above, and has a lower density from the grid 8 08 toward the substrate 8 0 1. The density is increasing. Deposition of a single Fe-C film on substrate 800 Is performed by opening the shirt 804 for a predetermined time.

The plasma P 2 generated by the configuration in FIG. 8 has a concentration gradient of plasma from the dalid 808 toward the base body 81, and the plasma concentration becomes maximum near the grid 808, and It has a distribution in which the concentration decreases as it approaches 0 1. In this apparatus, by using the substrate holding means 803 for supporting the substrate holder 802 for holding the substrate 801, the substrate 802 can be arranged along the direction in which the concentration gradient of the plasma P 2 is generated. It is equipped with a structure that can move 1 (arrows in Fig. 8) 3). As described above, the case where the ion gun 806 includes one crucible and the Fe—C base material 805 is provided therein has been described. However, the ion gun 806 may include a plurality of crucibles. According to this configuration, for example, by putting the Fe base material 805 ′ into the second crucible, α ′ —: Fe—C is formed on the substrate 801 in one film forming chamber 800. An Fe film can be formed instead of the film.

In the apparatus shown in Fig. 8, the distance t4 between the Fe-C base material 805 and the filament 807 in the ion gun 806 is 25 mm, and the distance t4 between the filament 807 and the grid 808 is The distance t5 was 95 mm, and the distance t6 between the grid 808 and the base body 81 was 60 mm. However, the distance t 6 is determined by the movement of the substrate 81 along the direction in which the concentration gradient of the plasma P 2 is generated using the substrate holding means 803 (arrow 3 in FIG. 8). Increase or decrease.

Further, during film formation, a magnetic field which is parallel to the film forming surface of the substrate 81 and has one direction is set so that the direction of the leakage magnetic field at the substrate surface position is the same direction even when the substrate 81 is rotated. Magnetic field applying means 8 13 composed of a permanent magnet to be applied was arranged. Base holder 8 0

The rotation of 2 and the opening and closing of the shirt 804 were controlled by a stepping motor (not shown) via a rotation introducing machine (not shown).

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. (Example 1)

In this example, using a facing target type sputtering apparatus shown in FIG. 7, the carbon (C) content in the film was 4 atomic% (at%) and the balance was iron (Fe). The layer 11 was directly deposited on the substrate 10 by a sputtering method to produce a sample S1 having a layer configuration shown in FIG.

At that time, sample S1 was prepared by changing the following three points.

(1) The substrate 701a is moved along the direction in which the concentration gradient of the plasma P1 is generated (the surface of the substrate 701a on which the iron carbide film is provided is exposed by the substrate holding means 703a, which can be arrowed in FIG. 7). It was formed by changing that plasma electron density N e in four conditions (7 XI 0 ^s cm one ^3, 2 X 1 0 ⁹ cm one ^{^{3, 1 X 1 0 10 cm}} ~ 7 X 10 10 cm -3).

However, the electron temperature of the plasma was fixed at about 0.1 leV by adjusting the pressure of the process gas.

(2) When forming the magnetic layer 11 made of an iron carbide film by a sputtering method, a temperature control means having a function of heating, cooling, or maintaining a constant temperature of the substrate built in the substrate holder 702 is used. The temperature of the substrate 701a on which the iron carbide film was provided was changed in the range of 0 ° C to 200 ° C.

(3) Only when the electron density N e of the plasma is 1 X 101 ^Q c π ³ , the carbon content X in the iron carbide film is 0.79, 2, 3, 4, 6 (at%). A modified sample was prepared. FIG. 2 is a schematic cross-sectional view showing the layer configuration of the magnetic thin film sample according to the present example, where 10 is a substrate, and 11 is a magnetic layer.

The substrate 10 was a glass substrate (Ko-Jung Co., # 7059). The film composition of the magnetic layer 11 was made from the iron carbide (Fe-C) alloy used for the film formation. the apparatus of the composition of the target 70 9 a, 70 9 b appropriately changed and the F e -4 at./ ₀ C by sputtering 7, iron carbide film (alpha '- - becomes the first data. F e- F e C film forming chamber 7 0 5 ultimate vacuum forming the magnetic layer 1 1 made of a C film) was fixed to 1 0- ⁷ Torr case (LTorr- about 1 3 3 P a), the deposition Occasionally, a magnetic field applying means 710 was used to apply a magnetic field [intensity: 30 to 50 gauss (G)] in one direction parallel to the film-forming surface of the base 701a. The temperature control rod stage built in the base holder 702 After heating the substrate 7 Ola in a vacuum at 200 ° C. for 2 hours, the substrate 701 a is cooled to a desired constant temperature of 0 ° C. to 200 ° C., and then heated at this temperature. The composition on the substrate 70 1 a is F e-4 a%. The "-Fe-C film was deposited. In this example, the -Fe-C film was formed using an alloy target composed of Fe and C manufactured by the vacuum melting method. Instead of the alloy tab, a target made of Fe and C produced by a sintering method, or a composite target in which a C chip is embedded on the Fe target may be used. A method for producing an α'-Fe-C film using a process gas including the Fe target may be used.Table 1 shows the film forming conditions for manufacturing the magnetic thin film of this example, that is, the sample S1. is there.

`` Table 1 J

Item setting value

Film formation method Opposite target sputtering method Substrate material Glass (# 70 59)

Substrate shape 8 mm square

Surface shape of substrate Mirror finish, Ra <1 nm

Degree of ultimate vacuum of the first deposition chamber 10 jorr level

Process gas Ar gas

Impurity concentration in Ar gas 1 10 ppb or less

Ar gas pressure 1-5 OmTorr (l.33-66.5Pa)

'Electron density N e 4 condition (7 X 10 ^s cnT ³ , 2 X 10 ⁹ cm "\

1 x 10 ¹⁰ cm ^1-3 , 7 10 ¹⁰ cm- ³ )

) Electron temperature T e about 0.1 e V: fixed

Retention temperature of tomb body surface 200 ° C (pretreatment)

0 to 200 ° C (o; '-F e-C film production) Target material Fe-C (G = 4at; balance Fe): Ne variable

Fe-C (C = 0.79, 2, 3, 4, 6 at ⁰ / o, balance Fe): When fixed to Ne (-1 X 10 ^{I 0} cm " ³ ) Target purity 3 N (FeC) Target shape Round

Target diameter t 19 Omm

Distance between targets t 2 10 Omm

Distance between target center and substrate t 3 9 Omm

Input power to target DC 200 W (Fe-C)

Application of magnetic field to substrate Application direction: One direction parallel to film formation surface of substrate

(Approximately parallel to the center axis between targets) Magnetic field strength: 30 to 50 G

'' Thickness of 30 Onm (Fe-C)

-Film formation rate 0.5 nm / sec (Fe-C) Below, the method of manufacturing the iron carbide film (Hi-Fe-C film) according to the present example is based on the case where Ne is variable. explain. The numbers in parentheses below indicate the steps.

When changing the composition of the α'-Fe-C film, fix Ne to 1 X 101 ⁽⁵ cm- ³ , and C = 0.79, 2, 3, 4, 6a " The difference is that a Fe-C target with a composition different from t ° / ₀ and the balance Fe was used.

(a 1) A base 701 made of glass having been subjected to a predetermined cleaning treatment is attached to a base holder 702, and is disposed on a base support in a load lock chamber (not shown). did.

(a 2) After the internal pressure of the load lock chamber reaches 10— ^e Torr, open the gate valve (not shown) that separates the load lock chamber from the sputter chamber 700, and always open the load lock chamber from the load lock chamber. — Using a means (not shown) for moving the substrate into the sputtering chamber 700 in a ⁷ Torr depressurized state, the substrate holder 702 on which the substrate 701 is set is placed on the substrate holding means 703. Moved. After that, the gate valve was closed.

The substrate holding means 703 is arranged at the center of the sputtering chamber 700, and is fixed to a rotation moving means 704 having a rotatable function made of a material of SUS. Here, the central portion is defined as a film forming space 1 for forming an α′—Fe—C film and a film forming space 1 for forming an Fe film by the shirts 70 7 a and 70 7 b and the deposition preventing plates 708 a and 708 b. Growth Question 2 Refers to the space provided between

(a 3) The substrate 701 a is moved to the side of the first film forming chamber 705 for forming an α′—Fe—C film by using the rotation moving means 704, and the temperature control means built in the substrate holder 702 a is moved. The substrate 701a was subjected to a heat treatment at 200 ° C. At that time, the shirt 70 7 a was closed.

(a 4) Thereafter, the temperature of the substrate 701 a was changed to a constant temperature between 0 ° C. and 200 ° C. by using the temperature control means built in the substrate holder 70 2 a, and the temperature was maintained.

(a5) Next, Ar gas at an appropriate flow rate was introduced into the first film forming chamber 705, and the gas pressure during film formation was set to a constant value between lmTorr and 5 OmTorr.

(a 6) Fe-C targets 709 a and 709 b are installed on the cathodes 7 16 a and 7 16 b by applying an arbitrary voltage from DC power source 714 to plasma: P 1 Occurred. As a result, the Fe—G targets 709a and 709b were sputtered.

At this time, the substrate 701 a is moved (in the direction of the arrow α in FIG. 7) along the direction in which the plasma concentration gradient is generated using the substrate holding means 703 a, and the surface of the substrate 701 a is moved. 4 conditions electron density N e of the plasma is exposed ^{^{(7 X 1 0 8 cm 3}} , 2 X 1 0 9 cm one ^{3, l X l O ^ cm} -3 YX l O ^ cnT 3) one of One. However, the electron temperature T e of the plasma was fixed at about 0.1 eV by adjusting the pressure of the process gas.

(a 7) While maintaining the state of (a 6) above, the shirt 7070 a was opened, and was parallel to the center line of the opposing first targets 70 9 a and 709 b made of the Fe—C alloy. On the surface of the substrate 701a at the position, a magnetic layer made of an α'-Fe-C film having a thickness of 300 nm was formed. The film thickness was controlled by the opening time of the shirt 707a.

By the above steps (a1) to (a7), the electron density N e of the plasma to which the surface of the substrate 701a is exposed is changed under four conditions (7 × 10 ⁸ cm— ³ , 2 × 10 ⁹ cm ” the 1 X 1 0 ¹⁰ cm one ^{^{3, 7 1 0 10 cm "}} 3) and a plurality of sample S 1 that was produced. 4, in Example 1, the electron density N e of the plasma 1 X 1 0 - was prepared by a ³ alpha '- crystal structure of the sample S 1 of F e-C film, as a radiation source (C o- It is a graph which shows the result of having investigated by the X-ray-diffraction method using (alpha)). (A) shows the results of sample S1 consisting of a Fe film fabricated using a pure iron target, as well as the results of sample S1 with a carbon content X of 4 at ° / _{0 in} the film. Was. (B) is the result of sample S1 prepared by changing the carbon content X in the film to 0.79, 2, 3, 4, and 6 at%.

As shown in Fig. 4 (a), the sample SF made of iron film prepared for comparison with the sample S1 made of '1-Fe-C film has a different crystal morphology because the angle at which diffraction lines are observed is different. It has been found.

In addition, from the result of sample S1 shown in FIG. 4 (b) in which the carbon content X in the film was changed to 0.79, 2, 3, 4, 6 at ° / ₀ , the diffraction line was 2Θ is obtained in the range of 70 ° to 77 °, and 2Θ is 20 ° to 115. It was found that other diffraction lines were not observed in the range. The diffraction line from α ′ (002) tends to shift toward the low angle side of 2 mm as the carbon content in the film increases, and this shift is caused by the (002) lattice space. Suggests an increase.

However, here, the electron density of the plasma Ne is 1 X 10 '. a 'was produced as cm- ³ - F e- C film sample S 1 has been described in detail in, strength weakened condition of the diffraction line from the (002) (e.g., ^{Ne = 5 X 1 0 1 (} ) C m_ 3 ), The intensity of the diffraction line from '′ (0 2) decreases, and the shoulder tends to be observed on the high angle side. And as the area of this shoulder increases, the coercive force He increases

The presence of a very large shoulder is not good. Conversely, by quantitatively capturing this shoulder, it is possible to easily determine whether or not a magnetic thin film having desired magnetic properties has been manufactured, and this is effective in constructing a stable manufacturing process. _{E that} can be used as important information

As described above, when the sample S 1 of the α′—F e—C film specified by the diffraction line from α ′ (002) is formed, the electron density N e of the plasma is determined under four conditions (7 × 10 ⁸ ^{^{cm- 3, 2 X 1 0 9}} cm ~ l X l O ^ cm- 3, 7 X was prepared by changing to 1 0 ¹⁰ cm- ³⁾ Fig. 1 shows the results.

Fig. 1 is a graph showing the relationship between the substrate temperature when producing an iron carbide film and the X-ray intensity of the (002) plane of the obtained iron carbide film. The intensity of the diffraction line I from the (002) plane of the iron carbide film prepared in step (1) is changed to the substrate temperature at which the intensity of the diffraction line from the (002) plane is maximized (for example, Ne = l Xl (T.cnT ³ In this case, the value was divided by the value I max of the substrate temperature = 25 ° C. In the parentheses in the figure, the surface roughness Ra of the produced iron carbide film was indicated by the in-site type STM. (Scanning tunneling microscope) The values shown here were obtained using an in-situ STM that allows in-situ observation in a reduced-pressure atmosphere. For example, the same measurement may be performed using an AFM (Atomic Force Microscope), etc. In Fig. 1, the dotted line indicates the case of N e = 7 X 10 ^Q cm— ³ , and the solid line indicates N e-1 X Ten Interview. Cm- ³ of the case, the case of the dashed line ^{^{Ne = 2 X 10 9 cm- 3}} , the two-dot chain line shows the case of a 7 X 10 ⁸ c ιι ^3.

First, the case of N e = 1 X 10 ^1Q cm one ³ shown in Figure 1: from (solid sample S 1 a), the following points became clear.

(1) When the substrate temperature is 5 ° C or higher and 100 ° C or lower, an X-ray intensity of 80% or more of Imax is observed, so that the desired α, 1-Fe-C film is considerably stable. can get. At this time, the surface roughness Ra of the produced —F e—C film is 0.2 to 0.3 nm.

(2) On the other hand, when the substrate temperature is between 125 ° C and 200 ° C, the diffraction line intensity from the (002) plane rapidly decreases as the temperature increases. From this, it was considered that the produced iron carbide film tended to deviate from the desired crystal structure.

(3) When the substrate temperature is 10 ° C or more and 70 ° C or less, since the X-ray intensity becomes 90% or more of Imax, the desired α'-Fe-C film can be obtained more stably. It is more preferable.

Also, by comparing the case of Ne = 1 × ¹⁰ × ¹⁰ cm— ³ (solid line: sample S 1 a) with the case of Ne = 7 × 10 ¹⁰ cm ″ ³ (dotted line: sample S 1 b), However, the following points became clear. (4) Sample S1b (dotted line) prepared using plasma with an electron density Ne higher than that of sample SIa (solid line) shows the substrate temperature at which X-ray intensity of 80% or more or 90% or more of Imax is observed. The upper limit value shifts to the lower temperature side by about 40 ° C. When the substrate temperature exceeds 60 ° C., the X-ray intensity of the (002) plane rapidly decreases. At this time, the surface roughness Ra of the produced α'-Fe-C film is larger than 0.5 nm, so that the surface is roughened and the flatness is deteriorated.

Furthermore, N e - l X l O ^ cm one ³ when: (solid line sample S 1 a), Ne = 2 X 1 0 9 cm- 3 in the case (one-dot chain line: the sample S 1 c) and 7 X 1 By comparing with the case of 0 ⁸ cm- ³ (two-dot chain line: sample Sid), the following points became clear.

(5) Samples Sic (dashed-dotted line) and Sample Sid (dotted-dotted line) prepared using plasma with electron density Ne smaller than sample Sla (solid line) have more than 80% or 90% of Imax. The upper limit of the substrate temperature at which the following X-ray intensity is observed shifts to a higher temperature side by about 20 to 30 ° C. When the upper limit of the substrate temperature is compared among four samples having different electron densities of the plasma, the maximum value is obtained in the sample S ic (the dotted line). At that time, the surface roughness Ra of the produced α'-Fe-C film becomes smaller than 0.1 nm, and the flatness is remarkably improved.

(6) The lower limit of the substrate temperature at which the X-ray intensity is 80% or more or 90% or more of Imax is lower than that of sample S1a (solid line). To buzz. In other words, it means that a magnetic thin film having a desired crystal morphology can be stably obtained even at a lower substrate temperature than the sample under the other three plasma conditions. From the results of the above (1) to (6), it is found that a plasma having a small plasma damage applied to the deposition surface of the substrate by using a process gas on the substrate disposed in the reduced pressure space, for example, the electron density of the plasma is 2 × 10 A plasma of about ⁹ cm— ³ is generated, and a single phase of α ′ phase is formed on the substrate using at least carbon and iron as constituent elements by using the plasma and a base material source for forming a magnetic thin film. According to the method of manufacturing a magnetic film having a step of forming an iron carbide film, the temperature of the substrate at which a desired iron film consisting of a single α 'phase is obtained can be reduced. It became clear that the range could be set wider. In addition, according to the above-described manufacturing method utilizing plasma having a small plasma damage, the surface roughness of the manufactured iron carbide film is significantly suppressed, so that the iron carbide film has good followability along the surface shape of the substrate. There are also advantages that can be formed. Therefore, according to the present invention, it is possible to provide a method of manufacturing a magnetic thin film capable of constructing a manufacturing process that is not restricted by the material constituting the base or the surface shape thereof.

In other words, according to the present invention, it is not necessary to limit the substrate temperature to a narrow range so much in order to produce a desired iron carbide film composed of a single α 'phase.

In other words, according to the method of manufacturing a magnetic thin film having the above-described structure, the problem caused by the difference in film formation temperature, that is, the difference in the surface material and surface shape of the substrate on which the iron carbide film is deposited is caused on the deposition surface of the magnetic thin film. Due to the temperature difference, the problem that the temperature range of the substrate on which the iron carbide film composed of the α′-phase single phase can be stably obtained is narrow can be greatly improved. In addition, the fact that the substrate temperature at the time of film formation in which an iron carbide film composed of an α′-phase single phase can be stably obtained is wider than before, which means that the conditions for producing the iron carbide film according to the present invention are relaxed. This means that the production margin can be expanded, and that mass production can contribute to lower costs.

(Example 2)

In this example, the electron density Ne of the plasma to which the surface of the substrate 701a on which the iron carbide film is to be exposed is exposed is changed in the range of ³ ^× 10 ⁸ cm — ³ to 7 × 10 ^{1 Q} cm ³ to contain A magnetic layer 11 having a film composition of 4 atomic% (at%) and a balance of iron (F e) was formed on a substrate 10. The sample was deposited directly by the sputtering method to produce a sample S2 having a layer configuration shown in FIG. Other points were the same as in Example 1.

FIG. 5 is a graph showing the relationship between the electron density Ne of the plasma and the X-ray intensity of the (002) plane of the obtained iron carbide when producing the iron carbide film. The X-ray intensity on the vertical axis shows that the diffraction line intensity I from the (002) plane and the diffraction line intensity from the (002) plane of the iron carbide film produced at the electron density of each plasma became the maximum. It expressed by the value obtained by dividing the numerical value I max in the case of the electron density of the plasma ^{N e = 2 X 1 0 9} cm- 3. From Fig. 5, when the electron density of the plasma is set to 7 X 10 ⁸ cm- ³ or more and 2. SX l O ^ cm- ³ or less, X-ray intensity that is 80% or more of I max is observed. It was found that the desired α'-Fe-C film could be obtained quite stably. On the other hand, when the electron density of the plasma is 3 × 10 ^] ° cm- ³ or more, the diffraction line intensity from the (002) plane rapidly decreases as the electron density increases. It is considered that the produced iron carbide film tends to deviate from the desired crystal structure. This trend was also seen in the case of the electron density of the plasma and 6 X 10 ^s cm one ³ below. Also, if the electron density of the plasma was 1 X 1 0 ⁹ cm- ³ or more 1 X 1 0 '° cm- ³ or less, since the X-ray strength degree equal to or greater than 90% of I max, the desired α '— F e — C film is more preferable because it can be obtained more stably.

(Example 3)

In this example, by changing the electron temperature T e of the plasma substrate 70 1 a surface providing an iron carbide film is exposed in a range of ^{2 X 1 0- 3 e V~7 e} V, the content of 4 atomic. /. A magnetic layer 11 (at%) having a film composition of iron (F e) was directly deposited on the substrate 10 by a sputtering method to produce a sample S3 having a layer configuration shown in FIG. At that time, the electron density N e of the plasma was fixed at about 3 × 10 ⁹ cm— ³ .

Other points were the same as in Example 1. FIG. 6 is a graph showing a relationship between the electron temperature Te of the plasma when the iron carbide film is produced and the X-ray intensity of the (002) plane of the obtained iron carbide film. The X-ray intensity on the vertical axis indicates the diffraction line intensity I from the (002) plane of the iron carbide film prepared at the electron temperature of each plasma, and the electron intensity of the plasma whose diffraction line intensity from the (002) plane was the maximum. It expressed by the value obtained by dividing the numerical value I max in the case of the temperature ^{T e = 1 X 1 0- 1} e V.

From FIG. 6, when the electron temperature of the plasma 4 X 1 0- ³ or less e V or 3 e V, since the X-ray intensity becomes 80% or more I. max is observed, the desired alpha '- It was found that the Fe-C film could be obtained quite stably. In contrast, carbide when the plasma electron temperature is below ³ X 1 0- 3 e V, as the electron temperature is reduced from (00 2) to diffraction intensity of the surface or we abruptly becomes small, prepared Crystal structure of iron film ^ ¹ hope We thought that there was a tendency to deviate from construction. This tendency was observed even when the electron temperature of the plasma was set to 4 eV or more. Also, if the electron temperature of the plasma was less 1 X 1 0- ² e V or more on 1 e V, since the X-ray intensity is more than 90% of I max, the desired α '- F e- C It is more preferable because the film can be obtained more stably.

(Example 4)

In this example, using the plasma deposition apparatus shown in Fig. 8, the carbon (C) content of the film was 4 atom ° / o (at%), and the magnetic composition of the film was composed of iron (Fe). The layer 11 was directly deposited on the substrate 10 by a plasma deposition method to produce a sample S4 having a layer configuration shown in FIG.

At that time, sample S4 was prepared by changing the following two points.

(1) The substrate 801 on which the iron carbide film is to be provided is exposed by the substrate holding means 803 which can move the substrate 801 in the direction in which the concentration gradient of the plasma P 2 is generated (arrow β in FIG. 8). The film density was changed while changing the electron density Ne of the plasma from 7 × ¹⁰ ⁸ cm ^{3 to} 7 × ^{10 10} cm- ³ . At that time, the electron temperature Te of the plasma was fixed at about 0.1 leV by adjusting the pressure of the process gas.

(2) When forming the magnetic layer 11 composed of an iron carbide film by a plasma deposition method, using a temperature control means having a function of heating, cooling, or maintaining a constant temperature of the base contained in the base holder 802. The temperature of the substrate 801a on which the iron carbide film was provided was changed in the range of 0 ° C to 200 ° C. FIG. 2 is a schematic cross-sectional view showing the layer configuration of the magnetic thin film sample according to the present example, where 10 is a substrate, and 11 is a magnetic layer.

A glass substrate (# 7059, manufactured by Koingen Co., Ltd.) is used as the base 10, and the film composition of the magnetic layer 11 to be manufactured is supplied to the film forming chamber 800 from the process gas inlet 811. The pressure and flow rate of methane (CH ₄ ) gas or thin)! The material consisting of iron carbide (Fe-C) alloy, which is the main raw material of the odor, is formed by changing the composition of 805 as appropriate and depositing it. e—4 at% C. In the apparatus of FIG. 8, magnetic layer composed of a '-F e-C film: arrival逢真Sorado deposition chamber 8 0 0 forming the L 1 is fixed to 1 0- ⁷ Torr base, formed At the time of film formation, a magnetic field [intensity: 30 to 50 gauss (G)] was applied in one direction parallel to the film formation surface of the substrate 801 using a magnetic field applying means 8 13. Before film formation, the substrate 801 was subjected to a heat treatment at 200 ° C. for 2 hours in a vacuum using a temperature control means incorporated in the substrate holder 802, and then the substrate 801 was cooled. After cooling to a desired constant temperature of 0 ° C. to 200 ° C., a single Fe-C film having a composition of Fe-4a was deposited on the substrate 801 kept at this temperature. .

In this example, the α'-Fe-C film was formed using the base material 805 of the alloy composed of Fe and C manufactured by the vacuum melting method. However, the sintering method was used instead of this alloy. A base material made of Fe and C, or a composite base material in which a C chip is embedded and installed on an Fe target may be used. Further, the usable process gas is not limited to the above-mentioned methane, but may be any gas containing the C element such as ethane and ethylene. Further, the simultaneous vapor deposition 2 using the base material made of Fe and the base material made of C is a typical film forming condition when the magnetic thin film according to the present example, that is, the sample S4 is manufactured.

"Table 2"

Item setting value

Film formation method Plasma deposition method

Substrate material Glass (# 70 5 9)

Substrate shape 8 mm square

Surface shape of substrate Mirror finish, Ra <1 nm

Of the deposition chamber ultimate vacuum of 1 0- ⁷ Torr table

Process gas CH4 gas

Process gas pressure 1-300 mTorr

) Electron density N e 7 X 1 0 ⁸ cm one ³ ~ 7 X 1 0 ¹⁰ cm one ³

) Electron temperature T e about 0.1 e V: fixed

Holding temperature of substrate surface 200 ° C (pretreatment)

0 ~ 200 ° C (α'-F e-C film production) Base material Fe-G (C = 4at ° /., Balance Fe)

Base material purity 3N (Fe-C)

Base material shape Lump

Distance between base material and filament t 4 2 5 瞧

Distance between filament and grid t5 9 5 cold

Distance between grid and substrate t660 (variable: 5 to 100 mm) Filament current If 0.1 to 10 A

Grid current I g 0.1 to 0.5 A

Grid voltage V g 50 to 500 V

Film thickness 50 Onm (α'-Fe-C film)

Deposition rate 0.1 nm / sec (a-Fe-C-monthly) In the following, the method for producing the α'-Fe-C film according to the present example is based on the case where Ne is variable. The following numbers in parentheses indicate the procedure.

(b 1) The substrate 801 made of glass having been subjected to a predetermined cleaning treatment is attached to the substrate holder 802, and is disposed in the substrate holder 802 in the film forming chamber 800. Then, the pressure in the film forming chamber 800 is reduced. .

(b 2) after the internal pressure of the film forming chamber 8 00 becomes equal to or less than 5 X 1 0- ⁷ Torr, it was degassing of the base material 80 5 made of F e- C (vapor deposition speed with respect to the base body 8 0 1 0.01 to 0.05 nm for about 60 minutes).

(b 3) the film forming chamber 8 After standing the introduced pressure process gas into the 00 to about 1 0 OmTorr as 5 minutes, under vacuum until again 1 0- ⁶ Torr stand the deposition chamber 8 00. This gas replacement operation was repeated three times.

(b 4) A process gas is introduced into the film forming chamber 800 to reduce the pressure to 10 OmTorr, and then a grid voltage Vg of 200 V is applied to the grid 808.

(b 5) Then, a filament current L 1 of 1 A flows through the filament 807, Generates plasma R2.

(b 6) The grid current I g is set to a desired value by the filament current I ί. As a result, a desired deposition rate is obtained on the substrate. At this time, since the gas pressure / grid current Ig fluctuates, it is preferable to finely adjust the deposition rate while adjusting both.

(b 7) After the deposition rate, gas pressure, and plasma are stabilized, the shutter 804 is opened, and the formation of the α′-Fe—C film on the base 801 is started.

(b8) When the desired film thickness is reached, the shirt 804 is closed to terminate the film formation.

(b9) After stopping the plasma by setting the grid current I g and the grid voltage V g to zero, the evaporation rate is gradually reduced, and the inside of the film forming chamber 800 is exhausted.

(blO) After using a cooling means (not shown) for the film forming chamber to set the film forming chamber 800 to approximately room temperature, the inside of the film forming chamber 800 was returned to atmospheric pressure with nitrogen gas, and the substrate 801 after film formation was taken out. . By the above steps (bl) to (blO), a plurality of electron densities Ne of the plasma to which the surface of the substrate 801 is exposed are changed in a range of 7 × 10 ⁸ cin— ³ to 7 × 10 ¹ ° cm— ³ . Sample S4 was prepared.

The plasma P 2 generated by the configuration in FIG. 8 has a plasma concentration gradient from the grid 808 toward the substrate 801, and the concentration of the plasma P 2 ′ having this concentration gradient becomes maximum near the Darlid 808, The distribution is such that its concentration decreases as it approaches 801. That is, the plasma P 2 ′ located in the vicinity of the base 801 has a very low concentration, in other words, a state in which the electron density Ne and the electron temperature Te are small.

The apparatus moves the substrate 801 in the plasma P 2 ′ in the direction in which the concentration gradient is generated by using the substrate holding means 803 supporting the substrate holder 802 holding the substrate 801 (FIG. It has a configuration that allows the arrow 8) 3).

Therefore, by using this apparatus, the electron density Ne of the plasma to which the surface of the substrate 801 is exposed can be set to a certain value in the range of 7 × 10 ⁸ cm— ³ to 7 × 10 ′ ° cm ^3. After that, a sample S4 composed of α′—Fe—C films of various compositions can be prepared on the substrate 801.

The thickness of the α'-Fe-C film deposited on the substrate 801 was controlled by the time to keep the shirt 804 at the ground potential from above the substrate 801, that is, the time to keep the shirt 804 open. . As in Example 1, the crystal structure of sample S4 produced in this example was examined by an X-ray diffraction method using (C o -—α) as a radiation source. As a result, the following points were clarified for sample S4.

(1) The sample formed under the condition that the plasma electron density Ne was small showed a tendency that the intensity of the diffraction line from C ′ (002) was higher.

(2) A graph similar to that shown in FIG. 1 (not shown), ie, the horizontal axis is the substrate temperature when forming the iron carbide film, and the vertical axis is the X-ray intensity of the (002) plane of the obtained iron carbide film. According to the study, it was found that the sample formed under the condition that the electron density N e of the plasma is small has a wider substrate temperature range where the vertical axis is 80% or more or 90% or more of I max.

From the above results, it is possible to obtain an α'-Fe-C film with a high intensity of the diffraction line from (002) even when the plasma deposition apparatus shown in Fig. 8 is used instead of the facing target type sputtering apparatus shown in Fig. 7. It became clear.

In other words, in order to stably obtain an α, 1-Fe—C film having a high intensity of the diffraction line from α ′ (002), a plasma with a small plasma damage applied to the deposition surface of the substrate is generated. A manufacturing method including a step of utilizing the plasma and a base material source for forming a magnetic thin film is effective. In addition, if the manufacturing apparatus has a configuration capable of forming a film under such plasma conditions, a magnetic thin film having desired magnetic characteristics regardless of the film forming method, that is, the present inventors have disclosed in Patent Application 2000 — An iron carbide film having a soft magnetization property having a saturation magnetization of 2 T or more and a coercive force of 2 Oe or less disclosed in 163822 can be manufactured extremely stably. That is, the opposed target sputtering apparatus shown in FIG. 7 and the plasma evaporation apparatus shown in FIG. Means for moving the substrate as shown in the deposition apparatus, that is, a mechanism capable of moving the position of the substrate surface along the direction in which the plasma concentration gradient occurs, and a substrate surface having a uniform concentration at least within the surface of the substrate. And a plasma generation mechanism capable of stably generating a plasma having a concentration gradient gradually along a direction perpendicular to the α-phase. Iron films can be manufactured very stably.

(Example 5)

In this example, a reference to the facing target sputtering apparatus shown in FIG. 7, including Murrell carbon (C) content is 4 to in the film 1 0 atom ^_0/0 (at%), cobalt (C o) containing Quantity is 10 atoms. /. (at%), and the balance is shown in FIG. 2 in which a magnetic layer 11 ′ made of an iron-cobalt carbide film having a film composition of iron (Fe) force is directly deposited on the substrate 10 by sputtering. Sample S5 having the layer structure shown was produced.

That is, the fifth embodiment is different from the first embodiment in that a magnetic layer 11 ′ made of carbon, iron and cobalt is formed on the base 10 instead of the magnetic layer 11 made of carbon and iron.

At this time, a sample S5 was prepared by setting the electron density N e of the plasma, the electron temperature T e of the plasma, and the temperature of the substrate 71 a as follows.

(1) The substrate 700a is moved along the direction in which the concentration gradient of the plasma P1 is generated (arrow a in FIG. 7). the 1 a surface electron density N e of the plasma exposed was fixed at about ^{^{2 X 1 0 9 cm "3}} . Further, by adjusting the pressure of the process gas, plasma electron temperature T e is about 0 le V fixed.

(2) When forming the magnetic layer 11 composed of an iron-cobalt carbide film by a sputtering method, a temperature control unit having a function of heating, cooling, or maintaining a constant temperature of the substrate contained in the substrate holder 720 is used. The temperature of the substrate 701 a on which the iron-cobalt carbide film was provided was fixed at about 20 ° C.

(3) A sample S5 was prepared in which the carbon content y of the iron-cobalt carbide film was changed to 4, 6, 8, and 10 (at%).

The other points were the same as in Example 1. FIG. 2 is a schematic cross-sectional view showing the layer structure of the magnetic thin film sample according to the present example, in which 10 is a substrate, and 11 'is a magnetic layer made of iron cobalt cobalt.

A glass substrate (# 7059, manufactured by Koingen Co., Ltd.) was used as the substrate 10, and the film composition of the magnetic layer 11 ′ to be manufactured was determined by the iron-cobalt carbide (F e—Co— C) By changing the composition of the first targets 709a and 709b made of alloy as appropriate, and sputtering, Fe-lOCo- (4 to 10 at%). And In the apparatus shown in FIG. 7, the ultimate vacuum degree of the FeCoC film forming chamber 705 for forming the magnetic layer 11 composed of the iron cobalt carbide film (α′—Fe—Co—C film) is as follows. 1 0- ⁷ Torr stand (1 Torr - about 1 3 3 P a) is fixed to. At the time of film formation, a magnetic field [intensity: 30 to 50 gauss (G)] was applied in one direction parallel to the film formation surface of the substrate 701a using a magnetic field applying means 710. Before the film formation, the substrate 71 a was subjected to a heat treatment at 200 ° C. for 2 hours in a vacuum using a temperature control means incorporated in the substrate holder 702, and then the substrate 70 1 a was heated. After cooling to about 20 ° C., α ′ composed of F e −10 at% C o − (4 to: L 0 at ^o / ₀ ) C on the substrate 70 1 a maintained at this temperature. In this example, an a'-Fe-Co-C film was formed using an alloy target composed of Fe, Co, and C manufactured by the vacuum melting method. Instead of an alloy target, a target consisting of Fe, Co, and C manufactured by sintering, or a composite target with a C chip embedded and installed on an alloy target consisting of Fe and Co was used instead of an alloy target. It does not matter. Alternatively, a method of producing a —Fe—Co—C film using a process gas containing a C element and an alloy target composed of Fe and Co may be used.

Table 3 shows the film forming conditions for manufacturing the magnetic recording film of this example, that is, the sample S5.

`` Table 3J

Item setting value

■ Film formation method Opposing target type sputtering method

-Base material glass (# 7 0 5 9)

-Base shape 8 mm square

-Surface shape of grave body Mirror finish, Ra <1 nm Degree of ultimate vacuum of the first deposition chamber 10 iorr level

Process gas Ar gas

Impurity concentration in Ar gas 11 Oppb or less

Ar gas pressure 1 ~ 5 OmTorr (33 ~ 66.5Pa)

Electron density N e 2 X 1 0 ⁹ cra " ³ : fixed

Electron temperature T e approx. 0.1 e V: fixed

The holding temperature of the substrate surface is 200. C (pre-processing)

20 ° C (at the time of a'-Fe-Co-C film production)

Target material Fe-Co-C (C = 4-10at%, Co = 10at% balance Fe) Target purity 3N (Fe-Go C)

Target shape Round

Target diameter t190mm

Distance between targets t 2 100 mm

Distance between the center of the target and the substrate t390 mm

Input power to target DC 1 50W (Fe-Co-C)

Thickness 30 Onm (Fe-Co-C)

0. ύ 5 sec (Fe-Co-C) A method for forming the iron carbide film (a single Fe-Co-C film) according to this example will be described below. The numbers in parentheses below indicate the procedure.

(c 1) After attaching a substrate 70 1 made of glass having been subjected to a predetermined cleaning treatment to the substrate holder 170 2, and disposing it on a substrate support stand in a load lock chamber (not shown), The pressure in the drock chamber was reduced.

(C 2) after the internal pressure of the load lock chamber became 1 0- ⁶ Torr stand, the gate valve (not shown) for partitioning the load lock chamber and the sputtering chamber 7 0 0, the load lock chamber or al always 1 in 0- ⁷ Torr stand reduced pressure into the sputtering chamber 7 0 0, moving the substrate The substrate holder 702 on which the substrate 701 was set was moved onto the substrate holding means 703 by using means (not shown). After that, the gate valve was closed.

The substrate holding means 703 is arranged at the center of the sputtering chamber 700, and is fixed to a rotation moving means 704 made of SUS and having a rotatable function. Here, the central portion is defined as a film forming space 1 for forming a Fe—Co—C film and a Fe film by the shirts 707a and 707b and the deposition preventing plates 708a and 708b. Refers to the space provided between the film forming space 2 for forming.

(c 3) The substrate 701 a is moved to the side of the first film forming chamber 705 for forming an α′—Fe—Co—C film by using the rotation moving means 704, and the substrate holder 702 a is built in. The substrate 701a was heat-treated at 200 ° C. by using a temperature control means. At that time, the shutter 707a was closed.

(c 4) Thereafter, the temperature of the base 701 a was changed to a constant temperature of about 20 ° C. by using temperature control means built in the base holder 702 a, and the temperature was maintained.

(c5) Next, Ar gas at an appropriate flow rate was introduced into the first film forming chamber 705, and the gas pressure during film formation was set to a constant value between lmTorr and 5 OmTorr.

(c 6) F e— C o— C Apply an arbitrary voltage from the DC power supply 7 14 to the power sources 7 16 a and 7 16 b on which the targets 709 a and 709 b are installed. Generated 1. As a result, the Fe—Co—C targets 709 a and 709 b are in a state where they are snow- and water-uttered.

At this time, the substrate 701 a is moved (in the direction of the arrow α in FIG. 7) along the direction in which the plasma concentration gradient is generated using the substrate holding means 703 a, and the surface of the substrate 701 a is moved. is fixed to the electron density N e of the plasma about 2 X 1 0 ⁹ cm- ³ exposed. The electron temperature Te of the plasma was fixed at about 0.1 eV by adjusting the pressure of the process gas and the like. ,

(c 7) While maintaining the condition of (c 6) above, the shirt 707a is opened, and the center lines of the first targets 709a and 709b made of the opposed Fe—Co—C alloy are opened. A magnetic layer made of a ct'-Fe-Co-C film having a thickness of 300 nm was formed on the surface of the substrate 701a at a position parallel to the substrate. The film thickness was controlled by the opening time of the shirt 707a. In this example, the film formation rate of the Fe-Co-C film (0.35 nmZs ec) is the same as the film formation rate (0.002 to 0.003) of Reference 3 described in the prior art. (nm / sec), which is about 100 times higher, and is fast enough for mass production.

Through the above steps (c1) to (c7), a plurality of samples S5 having film compositions having different carbon contents were produced by using Fe—Co—C alloy targets having different compositions. Fig. 9 shows the crystal structure of sample S5 consisting of the magnetic layer of the typical α'-Fe-Co-C film prepared in Example 5, using (Cu-Κα) as the radiation source. 6 is a graph showing a result of an examination by an X-ray diffraction method. In Fig. 9, the values (4, 6, 8, 10) shown above the diffraction peaks are the carbon contents of the magnetic thin film (Sample S5) where the diffraction peaks were observed. The carbon content of the magnetic thin film can be obtained from the S number by ESCA (Electron spectroscopy for chemical analysis), one of the X-ray photoelectron spectroscopy methods. For reference, FIG. 9 also shows the diffraction peaks of the bulk test (F e—10 at% Co).

As shown in FIG. 9, in the above configuration, the iron-cobalt film 11 ′ having a phase as a main phase is mainly composed of a diffraction line from the (002) plane of the phase, that is, a ′ (002) by an X-ray diffraction method. And are identified by being observed. FIG. 9 shows the case where only diffraction lines from the (002) plane of the iron-cobalt carbide film are observed. Although not shown, when the electron density Ne of the plasma and the electron temperature Te of the plasma were set differently from the values in Table 3, the same result as the iron carbide film shown in FIG. It was also observed in the iron-cobalt film. That is, the diffraction line from the (002) plane of the cobalt-iron-carbon film formed a main peak, and a protruded shoulder was observed on the high-angle side. In other words, the iron-cobalt film 11 ′ having the α ′ phase as the main phase according to the present invention has a diffraction line from the (002) plane of the single-phase and another diffraction line, that is, a broad line observed on the high-angle side. It has a crystal structure specified by the shoulder (shaded area). When the other diffraction lines disappear and a single crystal is formed, the iron carbide film 11 is composed of only the <¾ ′ phase single phase, and the α ′ phase (00 2 ) Only diffraction lines on the surface are observed.

From FIG. 9, it was found that in the manufactured sample S5 of the iron-cobalt film, only the diffraction line from the (002) plane of the h ′ phase, that is, α ′ (002) was observed. The diffraction line is 61 for 2 mm. ~ 6 3. Obtained in the range of 20-20. ~ 1 1 5. No other diffraction lines were observed in the range. The diffraction line from α ′ (00 2) tends to shift toward the lower angle of 2 mm as the carbon content in the film increases, and the shift is (00 2) This suggests an increase in the lattice space, which corresponds to the extension of the (002) plane spacing due to the penetration of carbon (C) into the c-axis.

Here, the description has been made using the sample S5 composed of only the carbon-iron-cobalt film. The same result as in Fig. 9 was confirmed for a thin film having the same interatomic distance, specifically, for a sample composed of an iron film and an iron cobalt film with the (200) plane as the surface. Figure 10 shows the lattice constants a and c of the ο; '— F e— C ο— C film measured by the Schulz reflection method, and the axial ratio cZ a obtained from these values with respect to the carbon content in the film. This is a plotted graph. From Fig. 10, it was observed that the lattice constant c tended to increase as the carbon content increased. On the other hand, the lattice constant a showed a tendency to decrease slightly with increasing carbon content, and a was almost constant at about 2.85. In addition, since the value of cZa is about 1.04 to 1.08, the obtained α'-Fe-Co-Cflelia has a body-centered tetragonal structure (bet structure: body-centered tetragonal structure). It became clear to have.

Although FIG. 10 has been described using the sample S5, a sample having a configuration in which the iron film or the iron-cobalt film having the (200) plane as the surface described above is provided between the base and the iron-cobalt carbide film may be used. The same result as in FIG. 10 was confirmed.

FIG. 11 is a hysteresis curve of an a′—Fe—Co—C film having a carbon content of 6 at ° / ₀ in sample S5 prepared in Example 5. (A) shows the bet structure (B) shows the results in the <100> direction of the bct structure, and (c) shows the results in the <110> direction of the bet structure. A vibrating sample magnetometer (VSM) was used for this measurement. The α'-Fe-Co-C film has a hard-axis c-axis from Fig. 11 (a) and an easy-c-plane from Figs. 11 (b) and (c). Can be confirmed. This suggests that by applying a positive or negative external magnetic field having an appropriate strength in the c-plane of the iron-cobalt carbide film, it is possible to easily control the reversal of the magnetization direction generated in the C-plane. .

(Example 6)

In this example, the opposed target sputtering apparatus shown in FIG. 7 was used, and the carbon (C) content in the film was 6 atomic% (at%) and the cobalt (Co) content was 0%. About 55 atomic% (at%), with the balance being a direct deposition of a magnetic layer 1 ′ ′ made of an iron-cobalt film having a film composition of iron (Fe) on the substrate 10 by sputtering. Thus, a sample S6 having a layer configuration shown in FIG. 2 was produced.

Other points were the same as in Example 5.

FIG. 12 is a graph showing the relationship between the cobalt content of sample S6 produced in Example 6 and the saturation magnetization Ms. From this graph, the range of the cobalt content 0-3 7 atoms ^{_{0/0 (at%),}} c saturation magnetization M s is 3 7 atoms saturation magnetization Ms with increasing cobalt content increases monotonously. After showing a maximum near / ₀ , the saturation magnetization M s starts to decrease monotonically with an increase in the content of konoreleto.

One Fe-C film (sample with 0 on the horizontal axis) has the same saturation magnetization M s [saturation magnetization M s = 210 e muZg as the α-Fe film, and the saturation magnetic flux density B s ~ 2.1 T (T represents a unit of Tesla)] (International Application No .: PCT / JP 00/0 8 16 7) Force Iron cobalt carbide film prepared in Example 6 It can be seen from Fig. 12 that the sample S6 consisting of exceeds the saturation magnetization of the α'-Fe-C film in a wide range of the cobalt content. In particular, it has been found that when the cobalt content is in the range of 12 to 50 atomic%, a cobalt-iron carbide film stably having a numerical value exceeding 2.2 T can be produced. Figs. 13 and 14 are graphs showing the results of investigation of the temperature change (M s-T curve) of the saturation magnetization. Fig. 13 shows the results when the cobalt content is 10 at. The case where the content of konokoku is 30 atom% is shown. Temperature change of the saturation magnetization is at ^{2 X 1 0- 7 T orr (} 2. 4 X 1 0- 4 P a) in a vacuum of, the heating and cooling rate was min 1 ° C (1 ° C / min) The temperature was measured from room temperature to 400 ° C.

From Fig. 13, it can be seen from Fig. 13 that the saturation magnetization decreases monotonically with increasing temperature when the temperature of the iron-cobalt film is 10 atomic% and the temperature increases (the curve shown by the arrow pointing to the right). 2 A sharp decrease is observed around 50 ° C. After this sharp decrease, the saturation magnetization again decreases monotonically). When the temperature drops (the curve indicated by the arrow pointing to the left), the saturation magnetization monotonically increases with decreasing temperature, and increases with an inflection point at about 230 ° C. The value is smaller than. It is considered that the rapid decrease in saturation magnetization at about 250 ° C during heating corresponds to the temperature at which the α 'phase decomposes into α phase and Fe ₃ C. The inflection point around 230 ° C when the temperature drops is considered to be due to the fact that Fe ₃ C whose Curie point is about 230 ° C has become magnetized.

In contrast, if the result Noreto content shown in FIG. 14 is 1 0 atom ^_0/0 of iron carbide cobalt film, curves for different aspects were observed. In other words, when the temperature rises (the curve shown by the arrow pointing to the right), the saturation magnetization monotonically decreases with the temperature rise, and when the temperature drops (the curve shown by the arrow pointing to the left), the saturation magnetization monotonically decreases with the temperature decrease. Increased. When the heat treatment temperature was up to 400 ° C, the point at which the sudden change in saturation magnetization was observed in the sample of FIG. 13 could not be confirmed at all. Figure 15 is a graph showing the relationship between the cobalt content and the point at which the saturation magnetization sharply decreases when the temperature rises (curve indicated by the rightward arrow) (hereinafter referred to as Tp.d.). Here, the decomposition temperature of the magnetic thin film Tp.d. (Phase decomposition temperature) is the temperature at the intersection of the tangent to the portion where the saturation magnetization sharply decreases and Define.

According to Fig. 15, the decomposition temperature Tp. D. Contains cono-kalt: S is 0 to 10 atoms. In the range of / ₀ , there is almost no change, about 260. C. Then, to the cobalt content of the 1 ² atoms ^_0/0 or more As a result, the decomposition temperature Tp. D. Showed an increasing tendency and exceeded 300 ° C. In particular, in a range of co Roh Noreto content 3 0-4 2.5 atomic ^_0/0, 40 0. No decomposition temperature Tp. D. Could be confirmed by heat treatment of C. Furthermore, when Yasu增cobalt content to 5 0 atoms ^_0/0 or more, the decomposition temperature Tp. D. Showed rapidly declining.

From the above results, it was determined that the iron-cobalt carbide film according to the present invention had a thermal stability exceeding 300 ° C. when the cobalt content was 12 to 50 atomic%.

(Example 7)

In this example, a reference to the facing target sputtering apparatus shown in FIG. 7, including Murrell carbon (C) content in H奠中0-2 0 atom ^_0/0 (at%), Kono Noreto (C o ) A magnetic layer 11 consisting of an iron-cobalt carbide film with a film composition consisting of iron (Fe) having a content of 30 atomic% (at%) Sample S7 having the layer configuration shown in Fig. 2 was produced by direct deposition.

Other points were the same as in Example 5.

FIG. 16 is a graph showing the relationship between the carbon content and the coercive force He of the sample S7 prepared in Example 7. In FIG. 16, marks indicate values after film formation, and marks indicate values after heat treatment at 400 ° C.

From FIG. 16, it was found that the coercive force of sample S7 made of an iron-cobalt carbide film can be reduced by performing a heat treatment after the film formation. In particular, it was confirmed that the coercive force of the cobalt-iron carbide film having a carbon content of 2 to 15 atomic% can be reduced to 2 Oe or less by a heat treatment at 400 ° C. for 2 hours.

From the results of Examples 6 and 7 described above, the iron-cobalt film according to the present invention was subjected to an appropriate heat treatment after the film formation, whereby a saturation magnetic flux density exceeding 2.2 T and a low magnetic flux density of 2 Oe or less were obtained. It has been found that it has a coercive force and also has heat resistance exceeding 300 ° C. FIG. 17 shows the crystal structure of the sample S7 comprising the magnetic layer of the representative α′-Fe-Co-C film prepared in Example 7 before and after heat treatment at 400 ° C. 7 is a graph showing the results of an X-ray diffraction method using (Cu-Ka) as an example. Fig. 17 When the carbon content is 6 atomic%, the curve is X 1 (before heat treatment) and the curve x 2 (after heat treatment). When the carbon content is 10 atomic%, the curve is y 1 (before heat treatment). And curve y2 (after heat treatment).

Figure 17 shows that the main diffraction peak observed from the iron-cobalt film changes from α '(002) to a (200) by the heat treatment without depending on the carbon content. Was. When 2Θ is in the range of 60 to 70 degrees, no diffraction peaks other than these peaks are observed.

However, when a hysteresis curve was measured for the sample S7 made of the iron-cobalt film after the heat treatment, the result before the heat treatment, that is, the hysteresis curve observed for the iron-cobalt film after the film formation shown in FIG. 11 was obtained. Almost the same result as the curve was obtained. The lattice constant was also measured for the heat-treated iron-cobalt film, but the result was not different from the result before the heat treatment, that is, the result observed for the film-deposited iron-cobalt film shown in FIG. .

From the above results, the iron-cobalt carbide film according to the present invention has a body-centered square structure without depending on the presence or absence of heat treatment performed after the film formation, the c-axis has a hard magnetization axis, and the c-plane has an easy magnetization surface. It was determined that the hard axis was substantially perpendicular to the film surface, and the easy magnetization surface was substantially horizontal to the film surface. Industrial applicability

As described above, the method of manufacturing a magnetic thin film according to the present invention, that is, using a process gas to generate plasma with small plasma damage to a deposition surface of the substrate on a substrate disposed in a reduced-pressure space, Utilizing plasma and a base material source for forming a magnetic thin film, utilizing the plasma and a base material source for forming a magnetic thin film, forming at least carbon and iron, or carbon, iron and Cobalt as a constituent element, for example, by X-ray diffraction using (Co-Κα) or (Cu-Kc) as a radiation source, the crystal structure of which contains a single phase of a martensite (α ') phase According to the manufacturing method having a step of forming an iron carbide film or an iron cobalt carbide film, which is confirmed to be, 髙 magnetic properties capable of responding to the increase in recording density, that is, saturation magnetization of 2 T or more and 2 Oe or less Good soft magnetic characteristics with a coercive force of A magnetic thin film with a stable at the substrate temperature during extensive deposition Can be formed. Further, even if an electron diffraction method is used instead of the X-ray diffraction method, it is possible to detect that the crystal structure of the iron carbide or iron cobalt carbide film according to the present invention includes a single phase of a martensite (α ′) phase. . Therefore, according to the method for manufacturing a magnetic thin film having the above-described structure, it is not necessary to restrict the temperature of the substrate to a certain range so much that it is less bound by the material constituting the substrate and its surface shape, and various materials and It is possible to provide a process that can stably and flexibly produce an iron carbide film or an iron cobalt film having a desired α ′ phase as a main phase on a substrate or a thin film having a surface shape. In the method of manufacturing a magnetic thin film having the above-described structure, the surface roughness of the formed magnetic thin film can be suppressed to an extremely small value by manufacturing the magnetic thin film using plasma with small plasma damage. The surface can be significantly flattened. Thereby, for example, even when the magnetic thin film according to the present invention is provided at the magnetic pole portion of a magnetic head composed of a large number of laminated films, good flatness at an interface between the magnetic thin film and the other thin films forming the laminated film can be obtained. Can be realized. Therefore, the method for producing a magnetic thin film according to the present invention can contribute to the production of a magnetic head having soft magnetic properties advantageous for high-density recording. The apparatus for manufacturing a magnetic thin film according to the present invention is characterized in that a process gas is used to generate a plasma with small plasma damage to a deposition surface of the substrate on a substrate disposed in a reduced-pressure space, thereby forming the plasma and the magnetic thin film. A base material source for use in forming an iron carbide film or an iron cobalt carbide film having at least carbon and iron or carbon, iron and cobalt as constituent elements and a main phase as the main phase on the substrate. A plasma generating means for forming the iron carbide film or the iron cobalt film, and a substrate holding means capable of moving the substrate along a direction in which the concentration gradient of the plasma is generated. Since the substrate is appropriately moved along the direction in which the plasma concentration gradient is generated by using the substrate holding means, damage to the deposition surface of the substrate from the plasma is suppressed. One can place the substrate into iron carbide film or possible iron carbide cobalt film forming position as the main phase of the desired alpha 'phase. By the way, plasma deposition equipment In the case of, the plasma state can be changed by the grid current and grid voltage. However, it is possible to control the plasma conditions to which the substrate surface is exposed, whether the plasma is constant or by moving the position of the substrate. According to the above configuration, the iron carbide film or the iron cobalt film hardly receives plasma damage at the start of the deposition, during the deposition, or after the deposition. It is possible to increase the film thickness in an atmosphere in an extremely small amount. Is suppressed. That is, according to the manufacturing apparatus having the above configuration, it is possible to stably manufacture a magnetic thin film having an extremely flat surface morphology.

In addition, when the flattening is promoted, the substrate temperature during film formation in which an iron carbide film or an iron cobalt carbide film having an α ′ phase as a main phase can be stably obtained can be made in a wide range. Thus, it is possible to provide a manufacturing apparatus having a wide temperature margin during manufacturing.

Furthermore, according to the above configuration, damage to the deposition surface of the substrate from the plasma can be suppressed, so that the material and shape of the substrate surface on which the iron carbide film or the iron cobalt carbide film is deposited can be reduced to α. '' This will contribute to the construction of a production line with high yield and high reliability, since the production equipment will be able to obtain an iron carbide film or iron cobalt carbide film whose main phase is very stable. The magnetic thin film according to the present invention is an iron-cobalt film having an α ′ phase as a main phase and at least carbon, iron and cobalt as constituent elements. Since it is 0 or less, it has a saturation magnetization corresponding to 2.2 ° or more without performing heat treatment after film formation. In other words, the atomic cobalt content. /. Thus, the iron-cobalt film with a value of 12 or more and 50 or less surpasses an a-Fe film or an _α'- Fe-C film having a saturation magnetization corresponding to about two, and furthermore has a value of 10%. It is possible to provide a magnetic thin film having a saturation magnetization higher than / ₀ .

In addition, the iron-cobalt carbide film having the content of cono-noret in the above-mentioned range does not cause a significant change in the crystal structure even when subjected to a heat treatment exceeding 300 ° C. Above all, including cobanoleto An iron-cobalt carbide film having a weight of 30 to 42.5 atom ° / ₀ has a heat resistance exceeding 400 ° C. Therefore, the atomic content of cobalt. The iron / cobalt film of which the ratio is not less than 12 and not more than 50 by the ratio of / ₀ is sufficient for the heat treatment at about 300 ° C required in the manufacturing process of the MR element constituting the magnetic head. Has resistance. Furthermore, the coercive force of the iron-cobalt carbide film according to the present invention can be reduced by performing an appropriate heat treatment after the film formation. Among them, the iron carbide cobalt film having a carbon content of 2 to 15 atomic% has a coercive force after heat treatment of 2 Oe or less and has good soft magnetic properties.

Therefore, the iron-cobalt carbide film having the above-described structure is a magnetic thin film which is mounted together with the MR element constituting the magnetic head and is extremely promising as a magnetic pole material constituting the magnetic head for writing.

Further, the iron carbide covanolate film according to the present invention is not formed by a thin film forming method using an etching process such as a conventional plating method, but by a sputtering method using a high-purity gas and a base material in an ultra-high vacuum. Because it can be manufactured using a dry process consisting of, the film thickness can be controlled with extremely high precision in the range of several nm to several hundred nm. This means that it is a magnetic thin film that meets the demand for thinner magnetic poles that make up the magnetic head for writing in order to achieve higher recording density.

Therefore, the method and apparatus for manufacturing a magnetic thin film according to the present invention contribute to the provision of a mass production technique capable of stably and highly accurately realizing a magnetic head capable of achieving a high recording density. It should be noted that the present invention can be implemented in various other forms without departing from its main features. The above embodiments are merely examples and should not be construed as limiting. The scope of the present invention is defined by the appended claims, and is not restricted by the specification text. Also, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

Claims

The scope of the claims

1. A process gas is used to generate a plasma with a small plasma damage to a deposition surface of the substrate on a substrate disposed in a reduced-pressure space, and the plasma and a base material source for forming a magnetic thin film are used. A step of forming an iron carbide film or an iron-cobalt cobalt film having at least carbon and iron, or carbon, iron and cobalt as constituent elements on the substrate, and a gallium phase as a main phase. Of manufacturing a magnetic thin film.

2. electron temperature T e of the plasma, 4 X 10- ³ method of manufacturing a magnetic thin film according to claim 1, characterized in that e V or more and 3 e V below.

3. electron temperature T e of the plasma, the method of manufacturing a magnetic thin film according to claim 1, characterized in that less than 1 X 10- ² e V or 1 e V.

4. The electron density N e of the plasma, 7 X 10 ⁸ cm- ³ or more 2. 5 X ¹⁰ 10 c m_ ³ method of manufacturing a magnetic thin film according to claim 1, characterized in that less.

5. The method for producing a magnetic thin film according to claim 1, wherein the electron density N e of the plasma is 1 × 10 ⁹ c π ³ or more and 1 × 10 ¹⁰ cm, ³ or less.

6. The magnetic thin film according to claim 1, wherein the step of forming the iron carbide film or the iron cobalt film containing the α ′ phase single phase uses a facing target sputtering method as a film forming method. Manufacturing method.

7. The method according to claim 1, wherein the step of forming the iron carbide film or the iron cobalt film containing the α ′ phase single phase uses a plasma deposition method as a film formation method. Method.

8. Step A of forming an iron carbide film or an iron cobalt film containing the CE ′ phase single phase Step B of forming a lower layer in contact with the iron carbide film or the iron cobalt film to form a lower layer and having the same interatomic distance as that of the iron carbide film or the iron cobalt film. 2. The method for producing a magnetic thin film according to claim 1, wherein the method comprises:

9. The method for producing a magnetic thin film according to claim 1, further comprising a step C of heating the iron carbide film or the iron cobalt film after step A.

10. A process gas is used to generate a plasma with small plasma damage on the deposition surface of the substrate on the substrate disposed in the pressurized space, and the plasma and the base material source for forming the magnetic recording film are formed. A production apparatus for forming an iron carbide film or an iron-cobalt carbide film having a main phase of at least carbon and iron, or carbon, iron and cobalt as constituent elements on the substrate,

A plasma generating means for forming the iron carbide film or iron carbide conoret film,

An apparatus for manufacturing a magnetic thin film, comprising: a substrate holding means capable of moving the substrate along a direction in which the plasma concentration gradient is generated.

1 1. The substrate holding means to variably control the position of the base body so that the electron temperature T e of the plasma the甚体are exposed is less than or equal to 4 X 1 0- ³ e V or 3 e V 10. The apparatus for producing a magnetic thin film according to claim 10, wherein:

12. The substrate holding means is such that the electron density Ne of the plasma to which the substrate is exposed is 7 × 10 ⁸ cnT ³ or more and 2.5 × 10 ¹ . 10. The apparatus for producing a magnetic thin film according to claim 10, wherein the position of the substrate is variably controlled so as to be not more than cm ³ .

13. The apparatus for producing a magnetic thin film according to claim 10, wherein the concentration gradient of the plasma is generated by a facing target sputtering method.

14. The apparatus for producing a magnetic thin film according to claim 10, wherein the concentration gradient of the plasma is generated by a plasma deposition method.

15. The magnetic thin film manufacturing apparatus according to claim 10, wherein the concentration gradient of the plasma is generated in a direction perpendicular to the surface of the base.

1 6. In addition to the plasma generating means for forming the iron carbide film or the iron cobalt film, a lower layer is formed in contact with the iron carbide film or the iron cobalt film, and the iron carbide film or the cobalt cobalt film is formed. 11. The magnetic thin film according to claim 10, further comprising plasma generating means for forming a thin film having an interatomic distance substantially equal to the interatomic distance of the film.

17. The apparatus for producing a magnetic thin film according to claim 10, further comprising a heat treatment unit for heating the iron carbide film or the iron cobalt film.

1 8. A magnetic thin film characterized in that the phase is a main phase and the film is at least carbon, iron and cobalt, and at least carbon, iron and cobalt are constituent elements. .

19. The magnetic thin film according to claim 18, wherein the iron-cobalt carbide film has a carbon content of at least atomic%, and is 2 or more and 15 or less.

20. The method according to claim 20, wherein, after the formation of the iron cobalt film, a diffraction peak from the (002) plane of the α 'phase is observed as a main peak by X-ray diffraction or electron diffraction. Item 18. A magnetic thin film according to Item 18.

2 1. The heat treatment of the iron-cobalt carbide film, wherein a diffraction peak from the (200) plane of the α phase is observed as a main peak by X-ray diffraction or electron diffraction. 8. The magnetic thin film according to 8.

2 2. The iron-cobalt carbide film has a body-centered square structure, the c-axis is a hard magnetization axis, The c-plane forms an easy magnetization surface, the hard magnetization axis is substantially perpendicular to the film surface, and the easy magnetization surface is substantially horizontal to the film surface. 20. The magnetic thin film according to 20 or 21.

23. A thin film having a lower layer in contact with the iron carbide film or the iron cobalt film and having an interatomic distance substantially equal to the interatomic distance of the iron carbide film or the iron cobalt carbide film is provided. 19. The magnetic thin film according to claim 18, wherein: