JP2001126221A - Method for manufacturing thin film magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for manufacturing a gap insulating film having a coating characteristic more excellent than that of the insulating film consisting of alumina film-formed by the conventional art with respect to the method for manufacturing a thin film magnetic head and to manufacture an element having high reliability in a high yield. SOLUTION: A plasma CVD method adopting aluminum alkoxide and oxygen as raw materials is applied to film-form a lower part insulating layer 43 and an upper part insulating layer 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method suitable for manufacturing a thin film magnetic head having a small distance between shields.

[0002]

2. Description of the Related Art In recent years, with the development of multimedia, the recording capacity of magnetic recording disks for computers has been increasing at a rate of 1.6 times per year.

[0003] In order to obtain a sufficiently large signal reproduction output from a recording bit that has been miniaturized due to the increase in density, a magneto-resistive effect (Magneto-resistive: M) is currently used.
R) Thin film magnetic heads using elements have been put to practical use.

[0004] Giant magneto-resistance (MR) elements and giant magneto-resistance effects called next-generation reproducing elements
In order to reproduce a signal recorded at a high density with a thin film magnetic head using an active (GMR) element, the MR element and the GMR element have characteristics that can sufficiently cope with a target recording bit and the resolution of a reading position. Improvement is needed.

For this reason, the MR element is configured to be sandwiched between the magnetic shield layers, and the positional resolution is improved as the distance (gap) L between the magnetic shield layers is reduced.

FIG. 5 is a cutaway side view showing a main part of a thin film magnetic head and a medium for explaining the reason for narrowing the gap. In FIG. 5, reference numeral 1 denotes an MR layer;
Indicates a gap, 4 indicates a medium, 4A indicates a recording bit, and L indicates a distance between magnetic shield layers.

By the way, the magnetic shield layer 2 and the MR (or GMR, hereinafter referred to as MR) layer 1 need to be electrically insulated, so that the distance between the magnetic shield layers is reduced. In order to improve the positional resolution, a thin insulating film made of a material having a high insulating property must be used. In the following description, the insulating film mentioned here will be referred to as a gap insulating film.

FIG. 6 is a cutaway perspective view of a main part of a general MR head, in which 11 is a substrate, 12 is a lower metal shield layer, 13 is a lower read gap insulating film, 1
4 is an MR layer, 15 is an electrode layer, 16 is an upper lead gap insulating film, 17 is an upper metal shield layer, and 18 is a write / read layer.
Gap insulating film, 19 is a coil, 20 is an upper magnetic pole, 21
Indicates a protective layer.

As a material of each of the gap insulating films 13, 16, 18, etc., SiO ₂ , alumina or the like is used (if necessary, see JP-A-58-220240).
JP-A-58-19718, JP-A-6-17
No. 6322 ”).

An MR head as shown in FIG. 6 is usually manufactured by using a thin film forming technique similar to the process for manufacturing a semiconductor device.

However, since a magnetic material is used for the MR head, the magnetic head must be manufactured under a temperature condition below the Curie point of the magnetic material in the manufacturing process, and a typical magnetic material, FeNi, is used. In this case, the manufacturing process must be performed at a temperature of 250 ° C. or less.

For this reason, when forming a gap insulating film,
EB (electron b) capable of forming a film at a relatively low temperature
eam) A vapor deposition method, a sputtering method, or the like is applied.
_{When two} films are formed, if the film thickness becomes about 500 [約] or less, the number of pinholes sharply increases, and the insulating property is deteriorated, which seriously affects the production yield.

As a method for solving this problem, MgO or La ₂ O _{3 is used as} a target when forming an alumina film.
Alternatively, it has been proposed to use alumina to which at least one of Y ₂ O ₃ is added.
-280323 (filed on September 30, 1999) ").

According to the proposed means, a film thickness of about 2
An insulation property of about 6.9 [MV / cm] can be obtained at 00 [Å].

However, the so-called physical vapor deposition (physical vapor deposition, sputtering, etc.)
In a deposition method collectively referred to as a vapor deposition (PVD) method, the thickness of a deposited film is reduced at step edges, pattern walls, and the like, resulting in poor coverage. Become.

[0016]

SUMMARY OF THE INVENTION The present invention provides a means for producing a gap insulating film having a coating characteristic superior to that of an alumina insulating film formed by a conventional technique, and has high reliability. An element can be manufactured with high yield.

[0017]

In the present invention, it is fundamental to appropriately select a raw material for forming a gap insulating film made of alumina and a film forming technique.

FIG. 1 is an essential part explanatory view showing a film forming apparatus for explaining the principle of a method of manufacturing a thin film magnetic head according to the present invention.

In the figure, 31 is a growth chamber, 32 is a gas inlet pipe, 33 is an exhaust pipe, 34 is a lower electrode, 35 is an upper electrode (susceptor), 36 is a high frequency power supply, and 37 is an upper electrode. The set substrate, 38 indicates a source gas introduced between the electrodes, and 39 indicates plasma generated by decomposition of the gas.

The well-known film forming apparatus is a plasma CVD (plasma chemical), as is well known.
It is an apparatus for performing a vapor deposition method, and in the case of the present invention, it is optimal to employ a film forming method based on this apparatus.

In order to deposit an alumina film on the substrate 37, the substrate 37 is set on the upper electrode 35 also serving as a susceptor, the inside of the growth chamber 31 is evacuated to a vacuum, and A gas mixture of aluminum alkoxide and oxygen, which is a gas, is supplied to the film forming chamber 31 and introduced between the lower electrode 34 and the upper electrode 35. When a high frequency voltage is applied to the lower electrode 34 from the high frequency power supply 36, the upper electrode 35 The source gas 38 is decomposed, and a plasma 39 is generated.

In the above state, the active species in the plasma 39 move onto the substrate 37 and cause surface diffusion and a reaction with the plasma active species, thereby depositing an alumina film on the substrate 37. It has been confirmed that the alumina film thus obtained has very good step coverage.

Such a result is obtained by using an aluminum alkoxide represented by a general formula of Al (OR) ₃ as a raw material of alumina;
z] Plasma C excited at a relatively low frequency of the order
VD is to be applied.

When an aluminum alkoxide is used as a raw material, the surface migration distance of the active species is lengthened and the coverage on the step is improved, and the plasma is excited at a frequency of the order of [kHz], so that the ion -Bombardment efficiency can be increased, and even if a raw material having a large number of carbon atoms is used, an alumina film having high insulating properties can be formed.

In the present invention, when forming an alumina film, an atmosphere in which oxygen and an organic aluminum compound are mixed to form a plasma is used. Therefore, in principle, any compound can be used as long as the raw material contains aluminum. Although it can be used as a raw material, aluminum and oxygen are combined in the raw material in order to maintain good coverage of the step featured by the present invention, and high insulation, It is preferable that an organic side chain is attached to the oxygen. Therefore, an aluminum alkoxide is preferably used.

As described above, in the method of manufacturing a thin film magnetic head according to the present invention, (1) the gap insulating layer (for example, the lower insulating layer 43) is formed by applying the plasma CVD method using aluminum alkoxide and oxygen as raw materials. And an upper insulating layer 45).

(2) In the above (1), the plasma CV
The power supply frequency when performing the method D is 50 [kHz] to 15
0 [kHz], or

(3) In the above (1), the aluminum alkoxide is aluminum tri-secondary butoxide ([C ₂ H ₅ CH (CH ₃ ) O] Al or Al)
(Sec.OC ₄ H ₉ ) ₃ ).

By adopting the above-mentioned means, it is possible to form a gap insulating film having remarkably good coating characteristics as compared with the coating characteristics of an insulating film made of alumina formed by a conventional technique. By using the insulating film, the distance between the magnetic shield layers in an MR head or the like can be reduced to improve the positional resolution, and a high-performance and highly reliable thin-film magnetic head can be manufactured with high yield. .

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A thin-film magnetic head according to the present invention
From the point of view of the configuration, it is no different from the conventional thin-film magnetic head, and the difference is the quality of the insulating film.
Here, a pseudo magnetic head having a structure convenient for measurement is prepared as a sample.

FIGS. 2A and 2B are main part explanatory views showing a sample which is a pseudo thin film magnetic head. FIG. 2A shows a main part cut side surface, and FIG. 2B shows a main part plane.

In the figure, 41 is a Si substrate, 42 is a first electrode layer, 43 is a lower insulating layer, 44 is a second electrode layer,
5 the upper insulating layer, the third electrode layer 46, 47 denotes the measuring instrument, respectively, also, L ₁ is the width of the groove formed on the second electrode layer 44, L ₂ is the second electrode layer 44 maximum width, L ₃ of
The maximum height of the second electrode layer 44, D _S is the thickness of at upper insulating layer 45 on the flat portion, D _W is the thickness of the upper insulating layer 45 of at the side walls in the groove of width L ₁ Each is shown. Incidentally, when the specific numerical values of L ₁ , L ₂ , and L ₃ are exemplified, L ₁ = 2 [μm], L ₂ = 300 [μm], and L ₃ =
300 [μm].

In the illustrated sample, each electrode layer is a gold (Au) layer formed by applying the EB evaporation method, and each insulating layer is formed by applying the plasma CVD method according to the present invention. The second electrode layer 44, which is an alumina layer, simulates a magnetic head.

When forming each insulating layer, the source gas is aluminum tri-secondary butoxide ([C ₂ H ₅ CH
(CH ₃ ) O] Al or Al (sec.OC ₄ H ₉ )
3) The mixture was bubbled with Ar and supplied to a parallel plate type plasma CVD apparatus to form an alumina layer.

The conditions for forming each insulating layer made of alumina are as follows: surface temperature of the Si substrate 41: 200 ° C. film forming pressure: 0.5 Torr plasma output: 100 [W] Al (sec. OC ₄ H) ₉ ) The flow ratio of 3 to O ₂ : 0.
02.

After the preparation of the sample, a measuring instrument 47 was connected between the second electrode layer 44 and the third electrode layer 46 to measure the dielectric breakdown voltage. The dielectric breakdown voltage is such that the leak current value is 1 × 1
The voltage when the voltage became 0 ^-6 [A] or more was set.

Further, step coverage, the ratio of the thickness D _W and the layer thickness D _S to be seen in FIG. 2 (A), i.e., was evaluated by D _W / D _S.

FIG. 3 is a diagram showing the results of the evaluation of the insulation properties. The horizontal axis represents the excitation frequency [MHz], and the vertical axis represents the average dielectric strength [MV / cm]. FIG. 4 is a diagram showing the results of evaluating the step coverage, wherein the horizontal axis represents the excitation frequency [MHz], and
The vertical axis represents D _W / D _S (sidewall layer thickness / surface layer thickness).

As shown in the figure, the excitation frequency is 50 [kHz]
In the range of [z] to 150 [kHz], the dependence of the layer thickness on the insulating properties and the step coverage can not be observed, and good insulating properties can be maintained even in an ultrathin film region of 500 [以下] or less. Is recognized.

For comparison with the above embodiment, a sample composed of a laminate of Au and an alumina layer, which is exactly the same as the sample shown in FIG. 2, was prepared by applying the sputtering method. The coating property was evaluated. The evaluation method was exactly the same as in the above embodiment.

The evaluation results show that the insulating property is 0.8 [MV /
cm] (layer thickness: 20 [nm]), 4 [MV / cm] (layer thickness: 50 [nm]), and the step coverage D _W / D _S is 0.5. Without a doubt, the insulating film according to the present invention was excellent.

In the present invention, without being limited to the above-described embodiment, many other modifications can be realized without departing from the scope of the claims.

For example, in the above-mentioned embodiment, aluminum tri-secondary butoxide was used as aluminum alkoxide among aluminum alkoxide and oxygen which are raw materials for forming the alumina layer.
Other aluminum alkoxide, i.e., triethoxy aluminum _{···· Al (OC 2 H 5)} 3 tri isobutoxy aluminum _{···· Al (i-OC 4 H} 9) 3 triisopropoxyaluminum · · · · Al ( i-OC ₃ H _{7) 3} trimethoxyaluminum ···· Al (OCH _{3) 3} tri-n-butoxy aluminum _{···· Al (n-OC 4 H} 9) 3 tri-n-propoxy aluminum · · · Al (n- OC ₃ H _{7) 3} tri-tert-butoxy aluminum _{··· Al (t-OC 4 H} 9) 3 , etc. can be used.

[0044]

According to the method of manufacturing a thin film magnetic head according to the present invention, a gap insulating layer is formed by applying a plasma CVD method using aluminum alkoxide and oxygen as raw materials.

By adopting the above configuration, it is possible to form a gap insulating layer having remarkably good coating characteristics as compared with the coating characteristics of an insulating film made of alumina formed by a conventional technique. By using the insulating layer, the distance between the magnetic shield layers in an MR head or the like can be reduced to improve the positional resolution, and a high-performance and highly reliable thin-film magnetic head can be manufactured with high yield. .

[Brief description of the drawings]

FIG. 1 is an explanatory view of a main part of a film forming apparatus for explaining the principle of a method of manufacturing a thin film magnetic head according to the present invention.

FIG. 2 is an explanatory view of a main part showing a sample which is a pseudo thin film magnetic head.

FIG. 3 is a diagram illustrating a result of evaluating insulation properties.

FIG. 4 is a diagram showing the results of evaluating the step coverage.

FIG. 5 is a cutaway side view of a main part showing a thin-film magnetic head and a medium for explaining the reason for narrowing the gap.

FIG. 6 is a cutaway perspective view of a main part showing a general MR head.

[Explanation of symbols]

41 Si substrate 42 First electrode layer 43 Lower insulating layer 44 Second electrode layer 45 Upper insulating layer 46 Third electrode layer 47 Measuring instrument L ₁ Width of groove formed in second electrode layer 44 L ₂ upper insulating film layer of the second maximum transverse width L ₃ second maximum vertical width D _S in the side wall into the groove of the thickness D _W width L ₁ of the in the upper insulating layer 45 on the flat portion of the electrode layer 44 of the electrode layer 44 45 layer thickness

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K030 AA11 AA14 BA43 FA03 JA06 JA18 LA02 5D033 AA02 DA02 5D034 BA15 BB08 BB20 DA07

Claims (3)

[Claims] 1. A method of manufacturing a thin-film magnetic head, comprising forming a gap insulating layer by applying a plasma CVD method using aluminum alkoxide and oxygen as raw materials. 2. The method according to claim 1, wherein a discharge frequency when performing the plasma CVD method is in a range of 50 [kHz] to 150 [kHz]. 3. An aluminum alkoxide comprising aluminum tri-secondary butoxide ([C ₂ H ₅ CH (CH
₃₎ O] Al or _{Al (sec · OC 4 H 9} ) 3) according to claim 1 method of manufacturing a thin film magnetic head, wherein a is.