JPS5954205A - Iron oxide magnetic thin-film - Google Patents

Abstract

PURPOSE:To obtain a medium for high-density magnetic recording suitable for a magnetic disk by previously adding a specific atom having a predetermined ratio to alpha-Fe2O3 when a thin-film mainly comprising alpha-Fe2O3 is heated in a reducing atmosphere and reduced into a thin-film mainly comprising Fe3O4 and the iron oxide magnetic thin-film is manufactured. CONSTITUTION:When the thin-film mainly comprising alpha-Fe2O3 is heated in the reducing atmosphere and the iron oxide magnetic thin-film mainly comprising Fe3O4 is manufactured, at least one kind of Pd, Au, Pt, Ru, Os Ag, Rh and Ir is made contain in alpha-Fe2O3 as an element to be added. When the element to be added is represented by a ratio only of a metallic element at that time, Pd is brought to 4.0%, and either of Au, Pt, Ru or Os is brought to 3.0%. Ag Rh or Ir is brought to 2.0%, a reducing reaction is promoted by these elements while a reaction temperature is dropped, and the iron oxide magnetic thin-film of high quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an iron oxide magnetic thin film suitable as a high-density magnetic recording medium, particularly as a magnetic envelope-task medium.

The conditioned iron magnetic 1q film is used as a material for magnetic disks, and is conventionally manufactured as follows.

First, a thin film containing a-Fe203 as a main component is formed on a substrate to a thickness of 1 μm or less by a known method such as a reactive sputtering method. Next, a thin film containing α-Fe203 as a main component is heated to about 300° C. in a reducing atmosphere such as H2 to reduce it to a thin film containing Pe3o4 as a main component. Pull @
Next, the thin film containing Fe3O4 as the main component was heated to about 300°C in an oxidizing atmosphere in the air to form γ-Fe20. Obtain a weak spring whose main ingredient is . When this γ-Fe2O3 thin film is used for a magnetic disk, an At alloy substrate whose surface is alumite-treated is currently most commonly used as the substrate. The purpose of alumite treatment is to harden the surface and improve head crush resistance. When this alumite-coated At alloy substrate is subjected to thermal processing, distortion occurs due to the difference in thermal expansion between the alumite layer and the At alloy base. The cracking on the disk surface induced by this strain increases rapidly at temperatures above 320° C., and in the worst case, cracks occur in the alumite coating. Defects on the bottom of the disk, such as the crank, result in missing recording signals and deterioration of the signal pair/44f ratio. Therefore, in order to obtain a uniform and high quality iron oxide magnetic thin film, the entire manufacturing process must be carried out at a temperature of at least 300°C.
Must be kept below.

During the media manufacturing process, the substrate temperature can be maintained at 300° C. or lower by employing a magnetron sputtering method or a high speed 150X/lT11n formation in the nupatting process. In addition, in the heating process, it is possible to convert the Fe3O4 thin film into a γ-Fe2O3 thin film by heating the Fe3O4 thin film in the atmosphere at 300°C for more than 2 hours.
However, in the reduction process, the heat treatment temperature is close to the heat resistance limit of the above-mentioned substrate. be. The purpose of cooling Co into a magnetic thin film is to increase the coercive force, and the amount of the cooling force 11 is usually 6 atomic % or less. Similarly, in order to improve the squareness ratio of a magnetic thin film, Ti is usually added at 5 atomic % or less, which causes problems, so conventionally a technology has been developed to lower the reducible temperature by adding 5 atomic % or less of Cu. There is o (J, AppL phys+ vol, 5
3+&L1982, ppz5s6-2560. /Ikeko Sho 55-14522 Special public Sho 55-14523. Q￥KoSho 56-33850゜Special Kosho 56-17818. % Kosho 5
6-23296 etc.) o L 7:P Si Cu addition 11
The limit for the reduction temperature reduction due to Co is 225°C;
1-Fe20. A new problem arises in that the saturation magnetization of the thin film decreases and the 1-1 reproduction output increases to 15 ('F).For example,
In the γ-Fe2O3 film to which Co, 'l'i, and Cu are added in combination in several atomic %, the saturation a is 33,000 au.
decreases to ss. Therefore, the amount of Cu added must be as small as possible, and the reduction treatment γ11. I wasn't able to lower my degree sufficiently.

As described above, in the conventional manufacturing method for iron oxide magnetic IN and film, reduction must proceed at a high temperature of 300°C, which causes cracks to occur in the alumite-coated At alloy substrate used for magnetic recording. Signal dropout and signal-to-noise ratio drop h! -λ was present.On the other hand, α-Fe203 is the main component? When reducing the tV membrane to form B% containing FejOaTh as the main component,
Since the reduction reaction proceeds from the membrane surface, if the thin film is thick, the lower layer of the membrane will not be reduced, and this unreduced portion will be the final product.
It remains in the thin film whose main component is Fe2O3.

Therefore, as the thickness of the iron oxide magnetic thin film increases, i't=
This has the disadvantage that the magnetization decreases when saturation occurs, and in the past, saturation was large and a thick iron oxide magnetic thin film could not be produced.

In the present invention, by separating the element that promotes the reduction reaction into an oxidized A41B thin film, the temperature at which the J17 element reaction proceeds can be reduced.
The purpose is to provide a 1V iron 1θ thin film with a sieving quality of 1V, and its formation is α
- Contains at least one kind of iron oxide magnetic thin film as an additive element, which is obtained by heating a thin film mainly composed of Fe203 in a reducing atmosphere to reduce it to a thin film mainly composed of Fe204. The present invention will be described in detail below.

In the present invention, Pd is used as an element that promotes the reduction reaction.

Au, Pt, Ilu, Ag, Rh
Alternatively, Ir is added to the thin film, and the reason why these elements promote the reduction reaction is that these elements belong to the Vllll group or the Ib group and have a lower concentration than Fe.
This is thought to be because the % negativity is large and the parent tree loca with oxygen is small.

That is, l? c Yojimo electron 7 □ Addition of Cu with large negativity, J -Fe, 20.7 > Expand the temperature to lower the temperature of Fe3O4, and change the negativity by 1 from e. ``Sana Ti's swimming style 1'' The edge is the original y+, the i degree is the island 7fl:A
It has been confirmed that it has the effect of expanding the river. In addition, C0 cancer 7Jl, which has the same electrical power as Fe, has an electric power of 11-3.
+ is 7.1 to the return reaction and to the shadow? There is no.

Therefore, based on the above results, the Vln group was selected in the present invention.

As shown in Table 1, group II) elements have larger tunic negativity than Fe, so it is thought that the diffusion effect can be extended to the low temperature side.Reduced film Ii of the present invention Expanding to the low-temperature side/The reason why A is larger than that of conventional nIJ Cu cooling is thought to be because the electron 2 negativity of the Ca 1 group and Ib elements taken up in this invention is smaller than that of Ct+. It will be done.

Next, examples will be shown.

Example 1 A thin film containing α-Fe203 as a main component was formed using the apparatus shown in FIG. That is, as shown in the figure, there are 98 atoms 96 with a diameter of 200 mm as the target 3 in the sputtering chamber 1.
-2 atomic % Co alloy plate Table-1 Rh' 2.2 is provided and on the shadow target 3 there is a swim direction 11 element plate 4 with a width of 5 mm + length of 5 mm, J! The Au board of the 5th cabinet is 4. d number 11. ';] It has 5 awns. By rubbing the 1+a description of this additive element plate 4 with J-kun, 41MhIri of the amount of IJ is white J-Kita. sputter number), 17J
1 is provided with an alumite-coated alloy substrate having an outer diameter of 210 yn as a substrate 2 facing the target 3,
In order to uniformly form a film, the sputtering chamber 1, which is rotated and slid, is pressurized with real nitrogen extraction system 6, and 50% 02-50% Ar is supplied from gas introduction system 7. - A sputtering gas was introduced into the chamber to form a sputtering atmosphere 42 with a pressure of 3X3-3'rorr. ○Furthermore, a high frequency magnetron sputtering method was used to sputter the substrate 2. Apply a low pressure of 3 kW sputtering 1 to the target 3 and apply a low pressure of 3 kW to the substrate 2.
Form a thin layer 11<=7 with e203 as the main component. There is only one force without putting 4. Also for %i combination etc. a-F
c20. A rocky film containing 'ic as the main component was formed. By the above method the form fik sat't, fC34! i(
Term] a Fe2O3i'JJ film t1 1\ of water was bubbled on the film [(2 from 100℃ to 35℃ in air flow)
It was heated in a temperature range of 0 °C for 3 hours, and the temperature range (hereinafter referred to as the appropriate reduction temperature range) in which a film containing Fe, (J4) could be formed was determined as 1jli·j. To identify the F"c and 04 resistance of this lifting platform, the electrical resistance of the membrane was measured using the two-pin method with a terminal spacing of 5. The resistance ranged from 103 to 10Ω (in Figure 2). The original film is mainly composed of Fe3O4, and the reduced film with higher resistance than D is a-Fe2U4 and Fe, 04 7 combination 4j.
J, D also confirmed that the low-resistance reduced film is Fe, a mixture of 04 and Fe. .Second Section 1A, C is 2), = When using only a Fe alloy target that dissipates % of CO, b t; 1 atomic % C
When u is added, a shows the relationship between the reduced r crystal 1jJ- and the turtle air mass 4 when Au is used as the additive element plate and AIJ with a metal element ratio of 06 atomic % is used. In the case of no fusion, the appropriate reduction γ quality in C2 is ρ
(i; M is 325°C from 300°C near 1:'J, which is the thermal limit temperature of the alumite AA alloy substrate.

-) Appropriate for 1 atomic % of 7 When adding 16 atomic%, the appropriate reduction temperature range for a is 175
℃ to 250℃, and further changed to low temperature 1111. It is clear from this beach vermilion that the present invention uses a couple IJ Motoaki's Au\icu) even with a small swimming style and amount.
, -Fe203 thin film 71) et al. Fe 304 illll
It is highly effective in promoting gas membrane reduction. The FTL abdomen, which is mainly composed of Fe3O4, of 3 cells and 11 cheeks, which were prepared by pulverizing and appropriate reduction treatment, was heated in a large pot at 300'C for 3 hours and 1 hour to form γ-Fe20. The oxidation was confirmed by the electron beam cycle and the Mössbauer effect.The obtained γ-F"e,
, for Ox #m saturation [1 magnetization, the input/(IQ force 11] C is 3300 Gauss, 1 atomic% Cu
3300 Gauss, and α
If 6BX child Taro's Au is 'lai)Ju, a is 3
700 Gauss s and 00 mm, 4 fortunes 7J et al. The γ-Fe 20 March recommendation of the present invention has a good textured Au with a corner Σ edge, so the conventional Cu-added γ-Fe and uncooled γ-Fe ,
, it can be seen that it has a saturation magnetization that is higher than that of the Oj group. The reason for this is thought to be as follows. The 11th saturation magnetization of fine particles j'F”e203 is approximately 5200
Conventional Noah-Fc203 thin rhh 1 fabricated by reactive sputtering and heat treatment despite having 0auss
'6p Ini 1 offspring Q, 1 about 3 (1'00~330
0 Gauss. In this way, γFe2,
The reason why the film has low magnetization is that the film is porous, the reduction is uneven in the direction, and the F of the film is low.
In the case where atomic % of a -Fe 203 is added to the non-magnetic material along the edge;
4I) As a result of the reduction to Qi being more consistent and the appropriate reduction temperature range being expanded to the lower temperature side, I
8304 朕 is formed, residual a −F'e 203 1
Since 1-1 decreases, 11 points are determined.

fi J, - α-F formed by sputtering
6,0, Thin R is a brother of a very small amount of fine material, and its composition can be determined by X-fold electron I\iR diffraction.
However, only a broad peak is obtained, and it is difficult to identify the α-Fe, U3 phase that remains in trace amounts after the reduction treatment.
The above estimation can be obtained from the comparative softness with other conventional examples.The example target is a 98 atomic% Fe-2JQ 1,000% CO alloy plate, and the machining elements are kg, Att, i'd.
.

A γ-Fe203jj containing only a proportion of gold scrap elements as shown in Pt, ILh, Ir, ILu or Us was prepared. The sputtering conditions are 8 x IQ”-31” sputtering atmosphere.
The process is the same as in Example 1 except that the sputtering power is lkw. The heat treatment conditions are also the same as in Example 1.

Table 2 shows the iron oxide magnetic thin/I produced by the above method.
Indicates the saturation of Q. As shown in the same table, each element's swimming method 1] Hatareta Usui 1 (〆 is also 34.00 Gau
ss, IJ, and these saturation magnetizations are different from the conventionally used Co-1-Cu or Co.
-1-Cu+'l'i 'f'1 combination rz sword nγ-F
'ez0MarK O saturation% - [1 magnetization is approximately 3300 Ga
Even though it is USS, it is 100 Gauss even if the ratio is 1 (branch).
All the above are delicious. The reduction temperature of the sample shown in Table 2 is below 225°C. Tazeta.

When Os is added to the tube, there is also a characteristic that not only the magnetization increases, but also the retention force increases by 1''. Conventional (7)
) r -Fe2Ua /j'Xl1nOsen', the magnetic force is 6500e and k is 7! , 0.55i of Os on the film
→) @ ij 9000e XO, 83
No negative % addition 11 shi j no 4 is 110 U Oe
, 18000e' when adding 9g of 2.13 atoms
The 1θ force maintained at Ii,x゛7 increased.

Thermal power 10 Example 3 98 bar 1j-1%Fe-2 atomic%CO as target
γ-F c 203 with an alloy rod of 1[1] and anisotropic (4.4 with Itu added up to 4.6 at% under the same conditions as in Example 2)
A total of 41 bases were formed, with the main component being 31st N1, H,
The relationship between the amount of u cooling and the 10-imaging of A1.11 cells whose main component is γ-Fe2O3 is shown. 1. u cooling amount is 3 atomic%
In the range shown in Table 2 below, a saturation magnetization higher than that of the sample without ILu added was obtained, but the saturation value decreased when the amount of nitrate was 3 at % or more. Therefore, if the amount of Ru 7JII is 3 at% or more, the effect of increasing the saturation magnetization increases (t
It is preferable. FIG. 3 also shows the minimum temperature of the appropriate reduction temperature. Conventionally, when Cu was added, the appropriate reduction temperature did not become lower than 225°C even if the amount of Cu added was increased. (If it is 14 atomic % or more, the reduction temperature is 2
The temperature can be 25°C or lower.

Similarly, when Au or Pt is oriented 1, 3 atomic%
With the following additive 7IO amount, even the conventional one has a high saturation power [1 magnetization of γ-F].
A Yl 7 film containing e2O3 as a main component was formed.

Vibration force of Ag, Rh or Ir (if 1, then 2
At an addition amount of atomic% or less, or 4 atomic% in the case of adding Pdi%
- A thin film containing Fe 203 as the main component was formed. Example 4 Using an alloy plate to which Co ((2 atomic %) and Ti 2 atomic % were added as a target, under the same conditions as Example 1, Au A γ-Fe20B thin film was formed with a vibration force of up to 1%.Other sputtering conditions and heat treatment conditions were the same as in Example 1.
The relationship between the saturation magnetization of a thin film whose main component is Fe2Q3 is shown. As in the case of using a target to which only Co is added, if the amount of Au added is 3 atomic % or less, AI' 2.
The saturation magnetization increases compared to the IL4-loaded sample. On the contrary, All
When more than 3 atoms are added, the saturation of octogenation decreases. Fourth
The lower limit of the appropriate reduction temperature is also shown in the figure. As shown in the figure, the magnetic thin film doped with All is different from that of conventional Cu.
This is different from the fact that addition can only lower the reduction temperature to 225℃! It has the effect of lowering the reduction temperature even more than that.

An oxide thin film was formed using Example 5 under the same conditions as Example 1 except for the following conditions. Chemical analysis revealed that this oxide thin film contains 0.5 at% of lLu as a metal element only (41(li)
Mg. This oxide, (the first limit of the yfi positive reduction temperature of the film is as low as 200℃, and the final
2 (J), the saturation magnetization of the thin film is 3500 Gauss. Note that even if pure Ar is used as the sputtering material under the conditions of this example, it is possible to form a thin film containing tb -Fc203 as the main component. By subjecting it to a magnetization and oxidation heat treatment, the magnetization reaches 3500 G.
A thin film containing γ-Fe2O3 as a main component was obtained.

The heat treatment conditions at this time were the same as those of FuhIQ Example 1. Example 6: Using a 98 atomic% Fe-21Q% Co alloy plate as the target and using ILu temporary as the additive element plate, Example 1
A γ-■·'e2Ug thin film was formed under the same conditions as described above. R1
1 was added by α5 atomic % in the metal element ratio] Samurai, Fe5
(The appropriate reduction temperature range for Jt# is 200℃~
The temperature decreased to 275°C, and the saturation magnetization of the γ-Fe2O3N film significantly decreased to 3900 Gauss. Also, this γ-Pe,,03 thin type has a coercive cuff (lQOe
,, The squareness ratio α8 and other magnetic properties also show a sharp 1-square, and have characteristics suitable as a medium for high recording density.

As described above in detail in the examples, the iron oxide magnetic thin film of the present invention can be produced by carrying out a supercharge reaction in a low-temperature oven in 16 rows.
- Power yaqjAz, even in pigeonholes that use alloy substrates, there is no jσt that causes cranks to occur on alumite workers, and it is possible to manufacture good magnetism. There is also the advantage that a homogeneous gun-like thin a is formed in the direction, increasing the saturation magnetization.
It is also possible to increase the coercive force by adding 5 to the added element.

[Brief explanation of drawings]

Figures 1 to 4 relate to the present invention; Figure 1 is a schematic diagram of the sputtering apparatus; Figure 2 Cj is a graph showing the relationship between the electrical resistance (Ω) of the film and the reduction humidity (°C); The figure shows saturation (・magnetization ((jauss
) and lowest] ■: 6 positive reduction Temperature reduction ((°C)
) for N31 sum magnetization (KGauss) k and the lowest suitable slope Y, l, X degrees (℃). is the target, 4 is the elephant cable plate, 5 is the frequency superimposition, 66' is the nitrogen exhaust system, 7 is the Ganu large system, a is 2%Co + 0.6%A, u (D addition) thin film,
b is 2%Co + l 9 (, Cu-doped thin film, L
- is 2% (? 0 repulsive force II), D is the appropriate reduction temperature range.
: i'"I' + Mr. Secretary J, 1 (Fi Indication Showa 57+1 Patent Application No. 164134 Shishi Showa Tll il' Part ゛[
7J2゛'mei0 name
Iron oxide magnetic thin film: 31:111i, ``%・S・') Relationship with '1' Patent applicant 4 Agent ~ 1.,, - ``Detailed description of the invention'' of the specification subject to the amendment and [-Brief Description of the Drawings J and Drawing 7, Contents of Amendment (7-1) "Detailed Description of the Invention 7" of the Specification shall be amended as follows. (A) Specification ■4 from the bottom of the 3rd page ?From the Jth → Fortune-
``Inspatuta method 2 [Using or u: 150 A/min high-speed film formation method]-'' written in the 3rd line indicates the substrate temperature...'' By doing so, the film formation rate was increased to 150 A/mi.
Even in the case of n and high speed, the substrate temperature...'' is corrected. (o) Write one name on the 5th line from the bottom of the 6th page of the detailed statement: k r Au r P', Ru + Ay,...J
'f r Au , P t r , lj+t l □
s. AJ..." he corrected. (c) The calendar was written on the 4th line from the bottom of the 8th vane of the details.
Thickness 5 rt+m J' (1,1 thickness 0.5 rtn
Correct it as q J. 2) "Force 3X3-L"(ll'r...thin film was completely formed.) described from line 7 to line 12 on page 9 of the specification [sputtering force 3X10-Torr] Here, the composition of the mixed gas ranges from 90% Ar -10% to 100%02, and the atmospheric pressure is 2 X l O='l''orr or more 8 X 10 -2T
If it is within the range of orr or less, the effect of promoting the reduction reaction basin as shown in this example can be obtained. Furthermore, high frequency McNetron sputtering 2 iC Yot) From high frequency electromagnetic wave 5 to substrate 2. A sputtering power of 0.3 KW is applied between the targets 3 and a 0.14 μm thick α-Fet is deposited onto the substrate 2.
A thin film containing Usk as the main component was completely formed. The maximum value of the electric power applied to the target was 2.5 Kw, but in this case as well, the effect of promoting the reduction reaction by adding it to the Au sputtered film can be obtained in the same way as in this example. ” he corrected. (e) It has suitable characteristics listed on page 19, line 4 of the specification. Add the following sentence r after J. "Also, the wear resistance properties of this 0.5 atomic% Ru-added yarn γ-P'e2O3 thin film magnetic disk surface are
o It was significantly improved from 1 to 1 compared to the Ti-1-Cu added yarn r-Fet03 membrane. The abrasion tester shown in Fig. 5 was not used, and eight lIn-Zn ferrite spheres with a diameter of 3 cm were fully pressed onto the disk surface rotating at a circumferential speed of 1 m/sec.
By measuring the depth of scratches on the disk surface after 00 rotations, the wear resistance characteristics of the disk surface can be evaluated. 6th
The figure shows the relationship between the load on the ferrite ball and the depth of wear scratches. The curve indicated by e in the figure is 2
/Jit child CQ + 0.5 atomic force Ru addition γ-Fe2
og thin film, and the curve indicated by f is 2 atomic%'Co
+ 2 IQ element % Ti + 1.5 atoms Ti Cu addition γ-
It is a Fe20s thin film. Co + 'I'i + Cu addition γ-rI''e20. The thin film is made of 2 at.% CO + 2 M at.% Ti + 1.5 at. % Cu addition Fe as a target matrix.
A plate was used, and the other manufacturing conditions were the same as in Example 1. As is clear from FIG. 6, the CO+■E11-doped γ-Fe203 thin film (e)
+Ti Compared to the Cu-added γ-Fe203 thin film (f), the depth of wear scratches under the same load is about one order of magnitude smaller, and the wear resistance is improved. Improving the wear resistance of the disk surface has a great effect on completely improving the head crash resistance of so-called node disks in which the head and the medium come into contact when the node starts or stops flying. Example 7 98 atomic% Fe''=-2 atomic% CO as target
A γ-Fez Os thin film was entirely formed using an alloy plate, a Ru plate and an Au sheet metal as additive element plates, and under the same conditions as in Example]. When Lu is added with a metal element ratio of 0.7 atoms and All is added with a metal element ratio of 0.3 atoms, the appropriate reduction temperature range for obtaining a Fe304 thin film expands to the lower temperature side, from 175°C to 275°C. Moreover, the saturation magnetization of the γ-1i'et Us thin film was 4000 Gauss, which is an even greater value.'' (7
-2) Details 1. Description 7 of "1111 Simple Explanation of Drawings" shall be amended as follows. (a) Same as above from line 4 of page 20 of the specification - (ji 5
``This is a graph.'' written on the first line. [Graph, Figure 5 is a schematic diagram of the abrasion tester, Figure 6 is the number of ferrite balls (9f) and the depth of wear scratches. μ・n
The relationship between 2? This is a graph that shows the correct result. (b) On page 20, line 17 of the specification; it, i
``D is the appropriate reduction temperature range.''? ``D is the appropriate reduction temperature range,'' Kozue said, and after this, he said the following sentence with all his might. 0 [8 is the disk, 9 is the motor, 10i1': I ferrite bulb, 11 J is bye, 12 is the idler nail. Total: 13 is the arm, 14 is the fine movement table, e is 2'%Co-1-0.5% Ru) Jll
Temperature: Membrane, f is 2% CO + 2 'I'i + 1.5
It is a thin film that has the force of the relation C1l. 7-3) Attached attachment No. 51 Threshold and Department

Claims (1)

[Claims] ■ An iron oxide magnetic thin film obtained by heating a thin film mainly composed of α-Fe203 in a reducing atmosphere to form a thin film mainly composed of FenO4. An iron oxide magnetic thin film characterized by containing at least one kind of additive element. (2. In Claim 1, the iron oxide magnetic thin film is characterized in that the thin film contains Pd as an additive element in a proportion of only the metal element of 4.01% or less. (, a, l 4′￥♂ “In the first claim,
C. A u of 8.0 atomic % or less in the proportion of only metal elements in the 11th thin group. An iron oxide magnetic thin film characterized by containing either Pt, f(u or O5) as an additive element. (4) Claim 1, wherein the thin film has a ratio of only metal elements of 2.0. h = Ag below Ag. An iron oxide magnetic thin film characterized by containing either R11 or Ir as an element.