JP2006260689A - Manufacturing method of magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly accurate processing method of a core width necessary in connection with the core width narrowing of a magneto-resistance effect film having a free layer in a magnetic head having a read head using a magneto-resistance element. <P>SOLUTION: This method includes the step of forming a resist on a magneto-resistance effect film including a free layer, the step of forming a protective layer on the surface of the resist and the magneto-resistance effect film by an atomic layer deposition method (ALD method), and the step of forming the magneto-resistance effect film with a desired core width by ion milling. Thus, highly accurate core width processing is carried out. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing a magnetic head for processing a core width of a read head using a magnetoresistive element with high accuracy.

  As a read head of a hard disk device, a magnetoresistive effect element that reads information written on a magnetic medium by using a magnetoresistive effect that changes the electric resistance by detecting the direction of a magnetic field leaking from the disk is known. However, this type of read head has a CIP (Current In Plane) structure in which a sense current for reading a resistance change is passed in parallel to the magnetoresistive film and a sense current in the thickness direction of the magnetoresistive film. It is known to have a CPP (Current Perpendicular to Plane) structure.

As the capacity of hard disk drives has increased in recent years, the recording density per bit has increased.
The core width of the magnetic head is becoming narrower. In the CIP structure, there is a problem that as the density increases, the resistance value decreases with the miniaturization of the magnetoresistive effect element, and the reproduction output decreases. On the other hand, in a magnetoresistive film having a CPP structure, since a sense current for reading a resistance change flows in a direction perpendicular to the magnetoresistive film, an output can be obtained regardless of the core width, and it is suitable for high density. It is said.

  Here, a magnetoresistive effect element having a CPP structure will be described with reference to FIG. FIG. 5 is an example of a principle configuration of a spin valve type magnetoresistive effect element having a CPP structure. On the lower electrode 51 also serving as a lower shield layer, an antiferromagnetic layer 52 and a magnetization direction are unidirectionally formed by the antiferromagnetic layer 52. The pinned layer 53, the nonmagnetic intermediate layer 54, and the free layer 55 whose magnetization direction easily changes under the influence of the magnetic field from the magnetic recording medium. An upper electrode 56 that also serves as an upper shield layer is provided so as to be connected to the upper electrode. Reference numeral 57 denotes, for example, an Al2 O3 planarization layer.

  When a sense current is passed in the perpendicular direction to the spin valve magnetoresistive film having a CPP structure, the resistance changes depending on the magnetization directions of the pinned layer 53 and the free layer 55, and it functions as a magnetic sensor that reads a magnetic field. Recently, a TMR (Tunnel Junction Magneto-Resistance) element using a tunnel magnetoresistive effect having a larger magnetoresistive effect is also known. In the read head using the magnetoresistive effect film having the CPP structure, the magnetic shield layer is provided above and below the magnetoresistive effect film so as to serve as the upper and lower electrodes. Therefore, the magnetoresistive effect of the CIP structure in which the magnetic shield layer is provided separately from the electrodes. Compared to a read head using a film, the gap length can be narrowed by an amount of an insulating layer necessary for insulating and separating the magnetic shield layer and the electrode.

  At present, GMR (Giant Magneto Resistive) heads with a multi-layer film structure of ferromagnetic and nonmagnetic materials alternately and with enhanced magnetoresistance effect due to an external magnetic field are practical for both magnetoresistance effects of CIP and CPP structures. It has become.

  Here, in the thin-film magnetic head having any of the above-described magnetoresistive effect films, the miniaturization of the magnetoresistive effect element advances as the recording density increases, and the processing conditions are severe in producing the element. Therefore, it is necessary to form the element with high accuracy without degrading the electric characteristics and magnetic characteristics of the multilayer film constituting the magnetic sensor element.

As a known example of this, for example, in JP-A-8-203036, a magnetoresistive film is formed by ion milling by forming a photoresist mask above the magnetoresistive film in order to form the shape of the magnetoresistive film. In the process of processing, the film thickness and ion milling speed of each layer of the magnetoresistive effect film composed of multiple layers are within a predetermined value range, and a portion behind the photoresist mask is adjusted by oblique milling. Thus, a method for producing a magnetoresistive head having excellent characteristics is disclosed. In JP-A-2000-221698, after etching an organic antireflection layer with a resist pattern, plasma irradiation is performed to form a cured layer on the resist pattern, and the layer to be etched is formed using the formed resist pattern as a mask. A method of patterning is disclosed. However, for applications such as machining the core width into high-precision dimensions, a method more suitable for the purpose has become necessary.
JP-A-8-203036 JP 2000-221698 A

  As a method of miniaturizing and increasing the sensitivity of the magnetoresistive effect element, the method of reducing the free layer width of the magnetoresistive effect element, that is, the core width, and masking a resist pattern formed on the magnetoresistive effect film with the core width. When forming by etching, the factors that determine the core width are the resist pattern width and the etching process. To narrow the core width, the resist pattern width is narrowed and an appropriate etching process is applied. It will be necessary.

However, under the present circumstances, the core width formation of several tens of nanometers has become a limit due to limitations and limitations on the resist formation process and the etching process, but efforts for further narrowing are continued.

  Here, an object of this invention is to provide the highly accurate processing method of the core width required with a core width narrowing.

  According to a first aspect of the present invention, in a manufacturing process of a magnetic head having a read head using a magnetoresistive element, a step of forming a resist on a magnetoresistive film including a free layer; A magnetic head comprising: a step of forming a protective layer on a surface and the magnetoresistive film by an atomic layer deposition method; and a step of forming the magnetoresistive film to a desired core width by ion milling. It is a manufacturing method.

  An example of a conventional film forming process is shown in FIG. FIG. 6 shows an example of a process after the multilayered magnetoresistive film 2 formed on the lower electrode 1 is formed. After forming the magnetoresistive film 2 by using a film forming technique such as sputtering, the width of the magnetoresistive film 2 in the longitudinal direction of the magnetoresistive film 2 facing the magnetic recording medium surface as a read head is determined by ion milling. In the process of processing, for example, in the process of processing the width of the free layer formed on the upper side of the magnetoresistive film 2 to a desired core width, before ion milling, first, in 1) resist patterning process, For example, a resist 3 having a T-shaped cross section is formed on the formed magnetoresistive film 2 by image reversal resist, and then 2) trapezoidal as shown in the figure by ion milling. Then, the process proceeds to 3) the step of forming a hard magnetic film / terminal film. A hard magnetic film 14 and a terminal film 15 are formed as shown in the figure. Here, 16 and 17 are unnecessary films having the respective compositions deposited on the resist 3 when the hard magnetic film 14 and the terminal film 15 are formed by sputtering, for example. Thereafter, 4) the resist 3 and unnecessary films 16 and 17 are removed in a lift-off process. Here, the surface of the magnetoresistive film 2 shown in FIG. 6 is positioned close to a magnetic recording medium surface (not shown) that rotates in a plane parallel to the paper surface after completion as a read head. ing.

  In the above-described manufacturing process 2) ion milling, regarding the width of the free layer of the magnetoresistive effect film 2 and the inclination of both end faces of the magnetoresistive effect film 2 indicated by a trapezoid, the milling angle is the magnetoresistive effect in the conventional method. If the film 2 is nearly perpendicular to the film surface, the fine particles scraped off from the magnetoresistive film 2 adhere to the side surface of the resist, ions are shielded, and the width of the free layer is effectively wider than desired. In addition, the inclination of both end faces of the magnetoresistive effect film 2 is large, and in the subsequent process 3) hard sputtering on the both end faces of the magnetoresistive effect film 2 during sputtering of the hard magnetic film 4 in the hard magnetic film / terminal film is performed. The surroundings of the magnetic film 4 are poor and sufficient characteristics as a head cannot be obtained. On the contrary, if the milling angle is slanted from the direction perpendicular to the film surface of the magnetoresistive film 2, the width of the free layer can be reduced, but at the same time, in the figure of the T-shaped resist 3, There is a concern that the thinned portion is milled and the resist 3 falls.

  According to the first aspect of the present invention, after the resist patterning step, the protective layer is formed on the resist and the magnetoresistive film by an atomic layer deposition (ALD) method. For example, an Al2 O3 oxide protective layer having a thickness of about 300 mm is formed as the protective layer. According to the atomic layer deposition method, Al and O are alternately stacked one atomic layer at a time, so that the film thickness can be managed by the number of cycles and the film thickness controllability is good, and the source gas is reacted on the wafer. By forming a film, a conformal film can be formed. For this reason, a film of a preferable material having a milling rate smaller than that of the magnetoresistive effect film is deposited by the ALD method on the film surface of the resist and the magnetoresistive effect film, and the conditions of the subsequent ion milling are selected, so that the magnetism suitable for the purpose The shape and core width at both ends of the resistive film can be obtained with high accuracy.

  Here, one or a plurality of free layers of the magnetoresistive film may be present on the upper surface, the lower surface, and the middle of the magnetoresistive film. For this reason, it is also possible to adjust the width of the free layer that becomes the core width of the magnetoresistive film by changing the shape of both ends of the magnetoresistive film.

  The invention according to claim 2 of the present invention is the method of manufacturing a magnetic head according to claim 1, wherein the milling rate of the protective layer is smaller than the milling rate of the magnetoresistive film. Here, when each of the protective layer and the magnetoresistive film is formed of a multilayer film made of different materials, the milling rate is the average milling rate of the entire multilayer film.

  According to a third aspect of the present invention, there is provided the magnetic head manufacturing method according to the first and second aspects, wherein the thickness of the protective layer is Al2O3 of not less than 50 angstroms and not more than 600 angstroms. When the thickness is within the range, even if there is a difference depending on the type and thickness of the magnetoresistive film, a practical and preferable role as a protective layer can be provided.

  According to the present invention, the core width of the magnetoresistive effect element including the shapes of both ends of the magnetoresistive effect film including the free layer can be finished with high dimensional accuracy.

FIG. 1 shows an embodiment of the production method according to the present invention: at the start of ion milling. In FIG. 1, as an example, a start stage of processing both ends of a spin valve layer 2 which is a magnetoresistive film formed on the lower electrode 1 by ion milling is illustrated. As shown in the structure example of the spin valve layer in FIG. 4, the spin valve layer 2 includes an antiferromagnetic layer, a pinned layer, an intermediate layer, and a free layer in order from the lower layer to be formed. As an example, the antiferromagnetic layer is made of PdPtMn, the free layer and the pinned layer are made of a ferromagnetic material such as CoFeB, and the intermediate layer is made of a material such as Cu or AlO.

  Each film forming condition, ion milling, and the like up to this stage are performed by generally known apparatuses and conditions.

Al ₂ O ₃ 4 already laminated on the resist 3 and the spin valve layer 2 is, for example, about 300 mm thick on the spin valve layer 2 by the ALD method, and about 300 mm on the surface of the resist 3. It is formed under conditions by an ALD method generally known for its thickness. Practically, the thickness of Al ₂ O ₃ is desirably 50 to 600 mm.

When the milling angle is 60 °, the ion beam is at an angle of 60 ° with respect to the surface of the spin valve layer 2 as shown in FIG. 1 and on the surface of the resist 3 on which Al ₂ O ₃ 4 is formed. Is incident at 30 °. FIG. 3 qualitatively shows an example of the milling angle dependence due to the milling angle between the spin valve layer and Al ₂ O ₃ . The spin valve layer is composed of a multilayer film, and the milling rate differs depending on the constituent material, thickness, etc., but the milling rate is generally larger in a wider milling angle range than the Al ₂ O ₃ protective layer formed by the ALD method. . The milling rate of the Al ₂ O ₃ protective layer is maximum when the milling angle is about 60 ° as shown in FIG. Thus, for example, a milling angle as 60 °, if the same as the thickness of the _Al 2 _{O 3} 4 of _Al 2 _{O 3} 4 resist side covering the spin valve layer 2, _Al 2 _{O 3} covering the spin valve layer 2 4 disappears before Al ₂ O ₃ 4 on the side surface of the resist, and milling of the spin valve layer 2 is started. Here, if the thickness of Al ₂ O ₃ 4 is appropriately determined within the range of 50 to 600 mm, the milling rate of the spin valve layer 2 is faster than that of Al ₂ O ₃ 4. Milling of the spin valve layer 2 is completed before the side Al ₂ O ₃ 4 disappears and resist milling is started.

  FIG. 2 shows one embodiment of the production method according to the invention: after ion milling. FIG. 2 shows the situation at the time of completion. In FIG. 2, both ends of the spin valve layer 2 are formed by two-step tapered surfaces. In this example, the spin valve layer 2 is located in the layer indicated by the width 5 of the free layer. FIG. In this way, changing the shape of both ends of the spin valve layer 2 depending on where the free layer is single or plural and where it is located is achieved by so-called oblique milling.

  As described above, according to the present invention, in the core width processing of the magnetoresistive effect element, the magnetoresistive effect can be obtained from the milling rate and the milling angle as a protective layer on the resist and the magnetoresistive effect film before the ion milling processing. In consideration of the material of the film, an appropriate protective layer is provided uniformly and evenly by the ALD method, thereby having a special effect of enabling fine processing. Furthermore, advanced processing with a narrower free layer width can be performed.

One embodiment of the production method according to the invention: at the start of ion milling One embodiment of the production method according to the invention: after ion milling Milling rate dependence of milling rate Example of spin valve layer structure Example of principle configuration of spin valve type magnetoresistive effect element having CPP structure Example of conventional film formation process

Explanation of symbols

1 Lower electrode 2 Magnetoresistive film 3 Resist 4 Al ₂ O ₃
5 Free layer width

Claims (3)

In the manufacturing process of a magnetic head having a read head using a magnetoresistive element,
Forming a resist on the magnetoresistive film including the free layer;
Forming a protective layer on the resist surface and the magnetoresistive film by atomic layer deposition;
Forming the magnetoresistive film to a desired core width by ion milling;
A method of manufacturing a magnetic head, comprising:   2. The method of manufacturing a magnetic head according to claim 1, wherein a milling rate of the protective layer is smaller than a milling rate of the magnetoresistive film. _{3. The} method of manufacturing a magnetic head according to claim 1, wherein the thickness of the protective layer is Al ₂ O ₃ of 50 angstroms or more and 600 angstroms or less.

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