JPH02301010A - Manufacture of thin film magnetic head - Google Patents

Abstract

PURPOSE:To manufacture a thin film magnetic head provided with a grind monitor with uniform quality with high mass producibility by comprising a thin film magnetic head element part and a grind monitor part on a substrate with first and specific second dry etching processings. CONSTITUTION:The patterning of a ferromagnetic film 25 on a yoke type magneto-resistance effect element head is performed with the first dry etching processing, and simultaneously, the patterning of U-shape of the ferromagnetic film on the grind monitor part 31. Next, an intermediate part 31a is eliminated by performing the second etching processing i.e. the etching processing by water solution including 10-15wt.% nitric acid and 5-15wt.% phosphoric acid, and the etching processing by the water solution including 2-10wt.% nitric acid and 50-70wt.% phosphoric acid in sequence noted above. Thereby, side etching can be prevented occurring, and patterning working of the grind monitor part can be performed with high reproducibility and high accuracy.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a method of manufacturing a thin film magnetic head.

More specifically, it relates to a method for manufacturing a thin-film magnetic head that records or reproduces information on a magnetic recording medium using a microfabrication technology such as photolithography, and in particular includes a polishing monitor section that can obtain a desired head height by polishing. The present invention relates to a method of manufacturing a thin film magnetic head.

(b) Conventional technology A thin film magnetic head obtained by processing a ferromagnetic thin film using microfabrication techniques such as photolithography has a narrower track compared to a magnetic head obtained by processing a conventional bulk ferromagnetic material. Since it is easy to form a magnetic head and a fixed gap, it is suitable as a recording or reproducing head for a high-density magnetic recording device. Furthermore, since it is easy to increase the number of elements, it is seen as a promising magnetic head for multi-channel fixed head type PCM recorders. In particular, in multi-channel fixed head PCM recorders, the speed of the magnetic tape is slow and the wire-wound magnetic head cannot provide sufficient playback output, so a ferromagnetic thin film with uniaxial magnetic anisotropy was used as the playback magnetic head. A magnetoresistive element (MR) is equipped with a magnetoresistive element (MR
A thin film magnetic head (MR head) is widely used, which is equipped with a magnetic recording element) and detects a signal recorded on a magnetic recording medium.

Since the above-mentioned MR element has a sensitivity characteristic showing a square change with respect to an external magnetic field, a predetermined bias magnetic field is required when a reproducing head is configured with this element. This bias magnetic field can be applied by providing a bias conductor near the MR element and inducing a bias magnetic field by passing a direct current through it, or by using a high coercive force thin film such as a Co-P layer. Methods such as applying a magnetic field are known.

Furthermore, compared to an MR head composed of a single MR element, the MR
A yoke-type MR head (YMR head), which has a magnetic flux introduction path (yoke) that separates the element from the head tip and guides the magnetic flux generated in the magnetic recording medium to the MR head, has better signal resolution and durability of the MR element. It is known to be beneficial in terms of improvement.

The YMR head type thin-film magnetic head for reproduction is manufactured by forming a magnetoresistive element on a predetermined substrate using microfabrication technology such as photolithography, cutting it into a predetermined size, and then placing it in a shield case or the like. It is obtained by storing the head and then polishing the surface in contact with the magnetic tape in the head gap portion to a predetermined size. For thin-film magnetic heads suitable for high-density magnetic recording, extremely high polishing precision is required in the polishing process described above. Therefore, conventionally, after manufacturing a thin-film magnetic head, a polishing monitor capable of detecting the amount of polishing in the head gap portion by a change in electrical resistance was formed on the same substrate as the thin-film magnetic head element and in the vicinity. The head gap area is polished based on the output.

And conventional YMR thin @ equipped with such a polishing monitor
A magnetic head usually includes a magnetoresistive element formed on one ferromagnetic substrate, and a thin film resistor of a predetermined area formed in the vicinity of the magnetoresistive element with an insulating layer interposed therebetween.
Next, after coating the entire surface with a ferromagnetic film, this ferromagnetic film is patterned to form a thin film magnetic head element portion of the upper and lower yoke type magnetoresistive element head structure, the thin film resistor, and the opposite sides thereof. It is manufactured by configuring a polishing monitor section consisting of a pair of strip-shaped ferromagnetic layers extending outside the resistor.

The conventional manufacturing method will be described below with reference to FIG. 5A.

This will be further explained in detail with reference to FIGS. 6B and 6A, B, and C.

First, as shown in Fig. 3A1, Fig. 4A, and Fig. 4B,
N1-Zn ferrite or Mn that also serves as the lower yoke
-Z S on a ferromagnetic substrate l made of n ferrite substrate
After forming a first insulating layer 2 of A1.in, 5ift, etc. by RF sputtering, P-CVD, etc., a layer of A1. A conductive layer made of Cu etc. is formed using RF sputtering method.
The conductive layer is formed by an EB method, etc., and then processed by a dry etching method, a chemical etching method, etc.
A bias conductor 3 for bias application is obtained. Next, a second insulating layer 4 is formed to cover this bias conductor 3. Next, a ferromagnetic layer [5 is formed on the second insulating layer 4 by a vapor deposition method, a sputtering method, etc., and then processed into a predetermined shape to form a magnetoresistive element (MR element).
is configured. Then, At film, Al-Cu alloy film, C
After forming the u film etc. by RF sputtering method, EB method etc.
The lead layer 6 is obtained by processing into a desired shape using a chemical etching method or the like.

Next, the portions of the first and second insulating layers 2.4 located in the front gap portion 7 are removed by taper etching by R,1,E (reactive ion etching), and then the MR element constituent portions are removed. and the upper yoke 12 described later.
The third insulating layer 8, which functions as a spacer layer between the
- Formed by CVD method, RF sputtering method, etc. Furthermore, the insulating layer of the back yoke portion 9, that is, the portion where the upper yoke 12 and the ferromagnetic substrate l serving as the lower yoke are connected, is R,
[,Etched by E.

Next, the thin film resistor 1 in the polishing monitor 11 to be described later
1a and the conductive layer 10 functioning as an adhesion layer are coated on the entire surface by RF sputtering and EB, and then the polishing monitor 11
A ferromagnetic film for forming the lead portions (band-shaped ferromagnetic layers) itb and zb and the upper yoke 12 is formed on the entire surface by sputtering, EB, or the like. Then, the lead IME (band-shaped ferromagnetic layer) LLB(
At this stage, as will be described later, the ferromagnetic film (middle part) on the thin film resistor 11a remains, forming a U-shape.)
patterning process. Thereafter, as shown in FIG. 381 and FIG. 4C, the ferromagnetic film (middle portion) on the thin film resistor 11a is removed by chemical etching, and a pair of leads extending from the thin film resistor and its opposite sides are removed. A polishing monitor 11 consisting of parts is obtained.

(c) Problems to be Solved by the Invention By the way, the width of the ferromagnetic film 5 constituting the MR element is
The thickness is set to 5 to 20 μm in order to increase the sensitivity of the Δρ/ρ characteristic of the element and obtain high output. Further, this ferromagnetic film 5 needs to partially overlap the upper yoke 12 in a three-dimensionally intersecting manner. For this reason, high precision is required for machining the upper yoke 12, and chemical etching, which requires a large amount of side etching, is inconvenient, so the machining of the upper yoke 12 must be performed using the dry etching method, as described above. be.

However, etching using the dry etching method has poor selectivity between the workpiece and other films (the difference in etching speed is small) and tends to be uniformly etched, which causes another problem. That is, as mentioned above, the upper yoke 1
At the same time as step 2, patterning of the lead portion (strip-shaped ferromagnetic material layer) 11b of the polishing monitor 11 is also carried out using the dry etching method. Due to the above characteristics of etching, there is a risk that the thin film resistor 11a itself exposed in the final stage of etching may be damaged or removed.

Therefore, the patterning of the pair of band-shaped lead parts 11b is first carried out during the dry etching process, in which the band-shaped shape of the lead parts is continuous with the ferromagnetic film (intermediate part) covering the thin film resistor 11λ, as described above. This is done by obtaining a U-shaped pattern, and then chemically etching the thin film resistor 11a using an etching solution that has virtually no etching properties to remove only the middle portion of the U-shaped pattern. . As this etching solution, it is conceivable to use an acidic etching solution such as a phosphoric acid-nitric acid type or a hydrochloric acid-nitric acid type.

However, the area of the thin film resistor 11a is usually determined by the width (w) depending on the intended polishing amount of the head gap portion, resistivity, etc.
is about 20 to 70 μm, and length 1) is about 50 to 200 μm
The area to be etched is very small. Therefore, it is difficult to visually judge when the necessary chemical etching has been completed (just etching), and as shown in Figure 3, over-etching often occurs in the side direction and the degree of over-etching occurs. The resistance varies from product to product, and due to industrial production, variations (typically about 1 to 30 μm) occur in the spacing between the leads on the thin film resistor.

Furthermore, before performing this chemical etching, it is necessary to remove the resist film that covered the U-shaped surface during the dry etching using plasma etching. Since a degraded layer due to oxidation etc. is often formed on the surface, and the thickness and properties of the parentheses vary from product to product, the etching rate itself also varies.
This increases the variation in the amount of overetching in the side direction.

This causes significant variations in the resistance values of the thin film resistors from product to product, which leads to variations in the amount of polishing, resulting in the problem that uniform polishing cannot be performed. Particularly in processing a large number of sheets, the variation was large, causing problems in mass production.

The present invention has been made to solve this problem, and can prevent over-etching due to chemical etching as much as possible, and in particular, can be etched under the same etching conditions even if the just etching time of the chemically etched object is different for each individual. The present invention aims to provide a method for manufacturing thin-film magnetic heads equipped with a polishing monitor of uniform quality with good mass productivity.

(d) Means for Solving the Problems Thus, according to the present invention, a magnetoresistive element is formed on one ferromagnetic substrate, and a thin film resistor of a predetermined area is connected to the magnetoresistive element through an insulating layer. A ferromagnetic film is formed near the element, and then the entire surface is coated with a ferromagnetic film, and then this ferromagnetic film is patterned to form a thin film magnetic head element portion having a yoke type magnetoresistive head structure, the thin film resistor, and the like. and a pair of strip-shaped ferromagnetic layers extending from the opposing sides to the outside of the resistor. In the patterning step, first, a first dry etching process is performed to At the same time as patterning the ferromagnetic film on the yoke-type magnetoresistive element head, the pair of strip-shaped ferromagnetic layer portions of the ferromagnetic film on the polishing monitor part become thin film resistors. A continuous U-shaped pattern is applied to the intermediate portion of the ferromagnetic layer covering the body, and then the intermediate portion of the U-shaped ferromagnetic layer is subjected to a second dry etching treatment, using 10% nitric acid. ~25
Etching treatment with an aqueous solution containing 5% to 15% by weight of phosphoric acid and 2 to 10% by weight of nitric acid, 50 to 70% by weight of phosphoric acid
There is provided a method for manufacturing a thin film magnetic head, characterized in that the polishing monitor section is formed by etching with an aqueous solution containing % by weight and then removing it in this order.

As the ferromagnetic material used as the material for the ferromagnetic substrate and various ferromagnetic films in the present invention, a material with high magnetic permeability is suitable, and a Ni-Fe alloy magnetic material is particularly preferred.
Examples include Ni-Zn ferrite, Mn-Zn ferrite, and the like.

Here, the thickness of the ferromagnetic film covering the magnetoresistive element (MR element) and the thin film resistor is usually suitably about 0.5 to 10 μm, and its formation can be carried out by various known methods. However, in order to construct an upper yoke with better magnetic properties, it is preferable to use a sputtering method and apply a negative bias voltage to the substrate side during sputtering. According to this method, a compressive stress N1-Pa alloy film with a value of internal stress mold = - (5 to 15) can be formed. However, in this case, since a large stress is applied to the MR element, Barkhausen noise may occur in the Δρ/ρ characteristic and the head characteristics may deteriorate. Therefore, in this case, a method of forming a stress canceling film is used.

For example, a Ni-Pa alloy film is deposited to a thickness of 500 mm using a vacuum evaporation method.
When the coating is formed by about 1 to 200 people, the stress applied to the MR element decreases to 172 to 1/4 because the stress of the deposited film is opposite to that when it is formed by sputtering. Therefore, a good Δρ/
The upper yoke can have a ρ characteristic.

As the specific structure of the magnetoresistive element in the present invention, a known structure can be applied, and an example thereof will be shown in the Examples described below.

Refractory metals are usually suitable for the thin film resistor in the present invention, such as Ti, Nb, and Mo.

Cr etc. are suitable. These can usually be formed by a vapor deposition method or a sputtering method.

The most distinctive feature of the present invention is that after the ferromagnetic film on the polishing monitor section is patterned in a U-shape by a first dry etching process, the middle part of this pattern is subjected to a second dry etching process. In addition, by subjecting it to a specific two-step chemical etching treatment and removing it, a polishing monitor portion having an intended structure can be formed.

Here, the first dry etching process can be performed by known dry etching such as ion milling, sputter etching, ion beam irradiation, etc.
Similar techniques such as dry etching treatment can be applied. Here, the second dry etching process only needs to be carried out to a sufficient extent to remove surface-altered parts such as an oxide film formed on the surface of the ferromagnetic film to be removed when performing the subsequent chemical etching. Examples are shown in the Examples below, and conditions can be selected as appropriate.

Thereby, the subsequent chemical etching process can be performed uniformly and smoothly.

After the second dry etching process, a two-stage chemical etching process is performed. Etching temperature is approximately 35
~60°C is suitable. Such chemical etching treatment is carried out using a nitric acid-phosphoric acid based etching solution, and in the first stage, 10 to 25% by weight of nitric acid and 5 to 1% by weight of phosphoric acid are used.
A 5% by weight aqueous solution is used, and in the second stage nitric acid 2-10
% by weight, an aqueous solution containing 50-70% by weight of phosphoric acid is used.

If the etching process is performed using only the first-stage etching solution, it is not possible to efficiently prevent sideward overetching and variations thereof during large-scale processing, which is not suitable. On the other hand, if the etching process is performed using only the second-stage etching solution, the etching process will take a long time and the amount of side etching will vary, which is not suitable.

However, it has been found that by combining these, over-etching in the side direction can be substantially prevented and patterning can be efficiently performed without causing quality variations due to over-etching even during mass processing.

Here, if the acid components in the first-stage and second-stage etching solutions each deviate from the above-mentioned ranges, it will be difficult to achieve the above-mentioned purpose and it will not be suitable.

Note that switching the etching conditions from the first stage to the second stage depends on the thickness of the ferromagnetic film to be patterned and the presence or absence of the above-mentioned stress canceling film, but it is usually about 1/3 of that.
The etching process may be performed using the first stage etching solution up to about L/1, and then the etching process may be performed using the second stage etching solution to complete the patterning.

(E) Effect The second dry etching process is performed on the middle part of the U-shaped ferromagnetic film on the polishing monitor part formed by the first dry etching process, thereby firstly changing the surface layer. A deteriorated layer mainly composed of an oxide film or the like that is inevitably formed is removed. Next, by performing the above-mentioned two-step chemical etching process on this treated surface, it is possible to pattern the pair of band-shaped ferromagnetic layers in the polishing monitor part without over-etching in the side direction and without variations. Become.

(F) Example Hereinafter, an example of the method for manufacturing a thin film magnetic head of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a schematic plan view showing a thin film magnetic head in the process of being manufactured by the manufacturing method of the present invention, FIG. 1B is a schematic plan view showing the finally obtained thin film magnetic head, and FIG.
Figure A is a sectional view taken along the line A-A in Figure 1A, and Figure 2B is a cross-sectional view of Figure 1A.
Fig. 2C is a sectional view taken along line B-B of Fig. 2, and Fig. 2C is a view corresponding to Fig. 2B showing the grain in the middle of bettering in the polishing monitor section, and Fig. 2 is a sectional view taken along C-C of Fig. 1B. It is.

Hereinafter, a specific manufacturing method of the present invention will be explained with reference to FIGS. 1 and 2.

First, a Sin film is placed on a strong electric pole substrate 21 which is made of a high permeability magnetic material such as a Ni-Zn ferrite or Mn-Zn ferrite substrate and functions as a lower yoke.

The first consisting of 5iOt, AltOz, etc. @ R the edge layer 22
After forming by F sputtering method etc., this first insulating layer 22
A conductive layer made of At, Cu, or the like is formed thereon by a vapor deposition method, a sputtering method, or the like, and then this conductive layer is processed by a dry etching method or a chemical etching method to obtain a bias conductor 23 for applying a bias magnetic field. Next, a second insulating layer 24 is formed to cover this bias conductor 23.

Next, a ferromagnetic thin film of Nt-
After forming the Fe alloy film 25 by sputtering or the like, it is processed into a predetermined shape by chemical etching to form an MR element. Next, after forming an Al@ or At-Cu alloy film on the entire surface, the lead layer 26 is obtained by processing into a desired shape by chemical etching or the like.

Next, the first and second
Taper etch the insulating layers 22, 24 with R, 1, E. Freon-14 (CF,
, ) etc. should be used. Next, a third insulating layer 28, which functions as a spacer layer between the MR element component and an upper yoke 32 to be described later and also functions as a gap layer in the front gap section 27, is formed by P-CVD or the like.

Further, a pack yoke portion 29, that is, an upper yoke 32 to be described later.
The edge layer where the ferromagnetic substrate 21, which is the lower yoke, is connected is R,! ', Etching is removed by E. Next, T
A high melting point metal film such as an i film, a Mo film, a Cr film, or a Nb film is formed on the entire surface by sputtering or vapor deposition.

Next, Ni-
An Fe alloy film (ferromagnetic film) (not shown) is formed on the entire surface (here, the thickness is approximately 0.5 to 0.7 μm) by sputtering using the negative bypass voltage application method described above. Furthermore, about 500 to 200
Coat with a Ni-Fe alloy film (stress canceling film).

Thereafter, the ferromagnetic film provided with the stress canceling film 32b is etched by dry etching such as ion milling, and the upper yoke 32 is patterned to form a yoke type MR element head, and the polishing monitor component is removed. Pattern it into a letter shape (see Figure 2C). Here, the U-shaped pattern is the polishing monitor 3.
This is a pattern in which a pair of lead portions 31b (band-shaped ferromagnetic layer) of 1 are connected by a ferromagnetic layer (intermediate layer) on the thin film resistor 31a (see FIGS. 1A and 2B).

In this example, the width of the pair of lead parts is approximately 200u@,
The length is about 2000 μm and the distance is about 200 μm.

Note that dry etching can be performed under various conditions, but in this example, the ion milling method was used, pure Ar gas was used as the introduced gas, and the flow rate was 8.
5SCCM1 Vacuum K I X 10-'Torr.

Argon beam irradiation angle to the substrate 30°, output = 3
The test was carried out under the conditions of 50V, Q, and 'aA. Note that under these conditions, the etching rate of the ferromagnetic film (Nt-Fe alloy) was about 100 people/min, and side etching was almost negligible.

Then, etching was performed on the middle portion of the U-shape. This etching was performed by first performing a second dry etching treatment and then subjecting it to two-stage chemical etching.

First, the second dry etching can be performed in the same manner as the first dry etching. The degree of etching removal is approximately 300 to 300% when the Ni-Fe alloy strong film does not have a surface stress canceling film.
Removal of 500 people is enough. Further, when a stress canceling film is formed on the surface as in this embodiment, it is appropriate to remove the thickness of the stress canceling film plus about 500 layers.

In this example, approximately 1500 particles were etched away from the surface using the same conditions as in the first dry etching described above (see Figure 2C).

Next, the middle part was immersed in an etching solution containing 17% by weight of nitric acid, 8% by weight of phosphoric acid, and 75% by weight of water for 15 seconds at 50°C. The polishing monitor 31 as shown in FIGS. 1B and 2 is removed by immersion in a second stage etching solution consisting of 66% by weight of acid and 30% by weight of water at 50° C. for 70 seconds. A thin-film magnetic head equipped with this was obtained.

Then, by this method, a large number of 6 sheets/batch (3 sheets in total)
When patterning was carried out on 0 sheets), the side etching of the lead portion 31b on the edge of the thin film resistor was within 2 μm at the maximum, which was practically negligible.

Therefore, in the manufacturing method of the present invention, over-etching in the side direction can be substantially prevented, and the patterning of the polishing monitor portion can be performed with high reproducibility and high precision even during mass production. Therefore, in particular, it is possible to prevent variations in the quality and output characteristics of the polishing monitor even during mass production, and as a result, the amount of polishing of the magnetic head can be made uniform, which in turn dramatically reduces variations in the playback output compared to the conventional method. It becomes possible to do so.

Regarding the two types of chemical etching solutions used in the above examples, standard Ni-Fe alloy thin @ (approximately 5000 people)
The degree of side etching was investigated. In particular, for the Ni-Fe alloy film, the time required for just etching with the first stage etching solution is 10 seconds at 50°C.
The extent to which side etching occurs when immersion contact is performed for about 30 seconds was investigated. Furthermore, the time required for just etching with the second stage etching solution is 50 minutes.
After recognizing that the temperature is 30 seconds, the extent to which side etching occurs was investigated when immersion contact was carried out for about 70 seconds. As a result, it was confirmed that the degree of side etching was suppressed to 1 μm or less in all cases, and was substantially negligible.

(G) Effects of the Invention According to the manufacturing method of the present invention, a thin film magnetic head equipped with a polishing monitor of uniform quality can be manufactured with good mass productivity, and as a result, variations in reproduction output of the thin film magnetic head are drastically reduced. becomes possible.

[Brief explanation of drawings]

FIG. 1A is a schematic plan view showing a thin film magnetic head in the process of being manufactured by the manufacturing method of the present invention, FIG. 1B is a schematic plan view showing the finally obtained thin film magnetic head, and FIG.
Figure A is a sectional view taken along the line A-A in Figure 1A, and Figure 2B is a cross-sectional view of Figure 1A.
Figure 2C is a view corresponding to Figure 2B showing the state of the polishing monitor part in the middle of bettering.The second diagram is a CC cross-sectional view of Figure 1B, Figure 3A , B are diagrams corresponding to FIGS. 1A and B for conventional manufacturing methods, FIG. 4A is also a diagram corresponding to FIG. 2A, and FIGS. 4B and C are diagrams corresponding to FIGS. 2B and D. . 21...Ferromagnetic substrate, 22...Middle East 1 insulating layer, 23...Bias conductor, 24...
Second insulating layer, 25...Ferromagnetic thin film, 26...
... Lead layer, 27 ... Front gap portion, 28 ... Third insulating layer, 30 ... Conductive layer, 31 ... Polishing monitor, 31a... Thin film resistor, 31b... Old lead part, 32... Upper yoke, 32b... Stress cancellation film. Figure 3 (A)

Claims (1)

[Claims] (1) A magnetoresistive element is formed on one ferromagnetic substrate, and a thin film resistor of a predetermined area is formed in the vicinity of the magnetoresistive element via an insulating layer, and then a ferromagnetic film is formed on the entire surface. After forming a coating, this ferromagnetic film is patterned to form a thin-film magnetic head element portion of a yoke-type magnetoresistive head structure, the thin-film resistor, and a pair extending from above the opposing sides to the outside of the resistor. In the patterning process, the ferromagnetic film on the yoke-type magnetoresistive element head is first etched by a first dry etching process. At the same time as patterning is performed, the pair of strip-shaped ferromagnetic layer portions of the ferromagnetic film on the polishing monitor portion are continuous at an intermediate portion of the ferromagnetic layer covering the thin film resistor. U-shaped patterning is performed, and then the intermediate portion of the U-shaped ferromagnetic layer is subjected to a second dry etching treatment with 10 to 25% nitric acid.
The polishing monitor portion is removed by etching with an aqueous solution containing 5-15% by weight of phosphoric acid and etching with an aqueous solution containing 2-10% by weight of nitric acid and 50-70% by weight of phosphoric acid in this order. A method of manufacturing a thin film magnetic head, comprising: