Dynamic magnetic information storage or retrieval – Head – Magnetoresistive reproducing head
Reexamination Certificate
1999-09-30
2002-06-11
Tupper, Robert S. (Department: 2652)
Dynamic magnetic information storage or retrieval
Head
Magnetoresistive reproducing head
C428S698000
Reexamination Certificate
active
06404603
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a thin film device comprising an insulating film, a thin film magnetic head including a pair of shield gap films made of an insulating film placed to sandwich a magnetoresistive element in between, a magnetoresistive element on which an insulating film is partially formed, and methods of manufacturing the same.
2. Description of the Related Art
Today, a composite thin film magnetic head is widely used as a thin film magnetic head. The composite thin film magnetic head has a layered structure which includes a recording head with an inductive-type magnetic transducer for writing and a reproducing head with a magnetoresistive (also referred as MR in the followings) element for reading-out. For example, as a reproducing head, an MR element sandwiched by a pair of shield films with a pair of shield gap films in between, is popular. Each shield gap film is provided for electrically isolating the MR element and each shield film, and is made of, for example, aluminum oxide (Al
2
O
3
) with high insulating characteristic.
In such thin film magnetic head, performance improvement in a reproducing head has been sought in accordance with improvement in surface recording density of a hard disk drive in recent years. Methods of increasing reproducing output of a reproducing head are: increasing amount of sense current flowing into an MR element; and shortening the MR height. The MR height is the length (height) between the end of the air bearing surface (the surface facing the recording medium) side and the end of the other side.
If the amount of sense current flown into the MR element is increased, however, Joule heat generated by the resistance increases resulting in a rise in the temperature of the MR element. As a result, reproducing output decreases and the MR element may not last long. Also, if the MR height is made shorter, Joule heat generated by the resistance increases resulting in a rise in the temperature of the MR element. Accordingly, reproducing output decreases and life of the MR element becomes shorter. Therefore, it is necessary to suppress a rise in the temperature of the MR element when increasing sense current or shortening the MR height.
In the related art, however, each shield gap film, which directly has a contact with the MR element, is made of aluminum oxide with a low thermal conductivity so that the heat generated in the MR element can not be effectively transmitted to each shield film. As a result, the heat of the MR element can not be effectively dissipated. In other words, a rise in the temperature of the MR element can not be suppressed so that the amount of sense current and the MR height are limited. Therefore, reproducing output can not be sufficiently improved.
Recently, to solve this problem, it is proposed in Japanese Patent laid-open Hei 5-205224 to form each shield gap film with aluminum nitride (AlN) with high thermal conductivity. In the related art, only an idea of forming each shield gap film with aluminum nitride is proposed.
Although the thermal conductivity of aluminum nitride is higher compared to that of aluminum nitride, it is not high enough to sufficiently increase reproducing output. Accordingly, sufficient radiation effect can not be expected only by simply forming each shield gap film with aluminum nitride.
In addition, the hardness of aluminum nitride is lower than that of the aluminum oxide. Accordingly, if the shield gap film is formed of aluminum nitride, the shield gap film is further polished compared to each shield film and the MR element at the time of polishing the air bearing surface, leaving a concave in the air bearing surface.
Further, aluminum nitride has a larger residual stress compared to aluminum oxide. Accordingly, if the shield gap film is formed of aluminum nitride, it becomes easy to exfoliate.
The invention is designed to overcome the foregoing problems. The first object is to provide a thin film device, a thin film magnetic head, a magnetoresistive element in which the thermal conductivity of the insulating film is improved, and methods of manufacturing the same.
The second object of the invention is to provide a thin film device, a magnetoresistive element device in which the thermal conductivity and the hardness of the insulating film is improved, and methods of manufacturing the same.
The third object of the invention is to provide a thin film device, a thin film magnetic head, a magnetoresistive element device in which the thermal conductivity of the insulating film is improved while the stress is decreased, and methods of manufacturing the same.
SUMMARY OF THE INVENTION
A thin film device of the invention comprises an insulating film which includes aluminum nitride, the (002) plane of which is oriented to the direction vertical to the surface of the insulating film.
In a thin film magnetic device of the invention, the (002) plane of aluminum nitride included in the insulating film is oriented to the direction vertical to the surface of the insulating film. As a result, a higher thermal conductivity can be obtained in the insulating film compared to the case where a plurality of crystal faces are oriented or to the case including aluminum nitride which is not oriented.
In a thin film device of the invention, the insulating film may include argon to obtain a higher hardness in the insulating film. For example, it is preferable that the content of argon by percentage lies within the range of 0.1 atomic % and 5.0 atomic %, or more preferable that it lies within the range of 1.0 atomic % and 3.0 atomic %. It is most preferable that it falls within the range of 1.5 atomic % and 2.5 atomic %.
Further, in a thin film device of the invention, the insulating film may include oxygen resulting in a decrease in stress. At least some portion of oxygen included in the insulating film may be chemically combined to at least either aluminum or nitride. It is preferable that the content of oxygen by percentage is lies within the range of 1 atomic % and 25 atomic %, or more preferable that it lies within the range of 5 atomic % and 20 atomic %. It is most preferable that it falls within the range of 10 atomic % and 15 atomic %.
A thin film magnetic head of the invention comprises: a magnetoresistive element; a first shield film and a second shield film placed to face each other sandwiching the magnetoresistive element in between for shielding the magnetoresistive element; a first shield gap film provided between the first shield film and the magnetoresistive element; and a second shield gap film provided between the second shield film and the magnetoresistive element. In the thin film magnetic head, at least part of at least either the first shield gap film or the second shield gap film is composed of an insulating film which includes aluminum nitride, the (002) plane of which is oriented to the direction vertical to the surface of the insulating film.
In a thin film magnetic head of the invention, information is read out by flowing sense current into a magnetoresistive element. At this time, Joule heat is generated by sense current in the magnetoresistive element. The heat is transmitted to a first shield film and a second shield film through a first shield gap film and a second shield gap film, respectively, to be dissipated. At least part of either the first shield gap film or the second shield gap film includes aluminum nitride, the (002) plane of which is oriented to the direction vertical to the surface of the insulating film. Accordingly, at least either the first shield gap film or the second shield gap film comes to have high thermal conductivity. As a result, the heat generated in the magnetoresisitve element is effectively dissipated and a rise in the temperature is suppressed.
In a thin film magnetic head of the invention, the insulating film composing at least part of either a first shield gap film or a second shield gap film may further include argon. In such a case, the hardness of at least either the first shield gap film or the secon
Inoue Toru
Terunuma Koichi
Oliff & Berridg,e PLC
TDK Corporation
Tupper Robert S.
Watko Julie Anne
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