BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention will now be described by way of examples and with reference to the accompanying drawings, in which:
FIG. 1A-1E are partial sectional views showing steps of the method of an embodiment of the present invention;
FIG. 2F-2I are partial sectional views showing further steps of the method of the embodiment of the present invention;
FIG. 3G-3I are partial sectional views showing further steps of the method of another embodiment of the present invention;
FIG. 4 is a partial sectional view of the thin film magnetic head of an embodiment of the present invention;
FIG. 5A-5E are partial sectional views showing steps of the conventional method of producing the thin film magnetic head;
FIG. 6 is a partial sectional view of the conventional thin film magnetic head; and
FIG. 7 is a partial sectional view of another conventional thin film magnetic head.
DETAILED DESCRIPTION OF THE EMBODIMENTS
Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
The thin film magnetic head of the present embodiment is used for a magnetic disk drive unit and has a read-element constituted by a magnetoresistance effect element, e.g., tunnel junction element (TMR).
A method of producing the thin film magnetic head of the present embodiment will be explained with reference to FIG. 1A-1E, FIG. 2F-2I and FIG. 3G-3I.
In FIG. 1A, a lower shielding layer 4 is formed on a wafer substrate 2. Note that, explanation of a structure between the wafer substrate 2 and the lower shielding layer 4 will be omitted.
A separating layer 5 is formed on the outer sides of the lower shielding layer 4.
Next, a tunnel junction element layer 6 is formed on the lower shielding layer 4.
A resist layer 8 is formed on the tunnel junction element layer 6 by a photolithographic method. The resist layer 8 is formed and corresponded to a position (a resist layer 8a), at which a read-element (described later) will be formed, and areas (resist layers 8b) covering the tunnel junction element layer 6 except specific areas, in which a hard bias film (described later) will be formed. The resist layer 8 is constituted by two different photoresist layers: a lower sub-layer and an upper sub-layer. A thickness of the lower sub-layer is thinner than that of the upper sub-layer.
The resist layers 8a and 8b are formed, and a specific area, in which the hard bias film will be formed, between the resist layers 8a and 8b is made broader than an area, in which an upper shielding layer (described later) will be formed. Namely, when the resist layers 8a and 8b are formed, the specific area is defined so as to outwardly project outer edges of the hard bias film in a plane-direction from those of the upper shielding layer in the same direction.
In FIG. 1B, parts of the tunnel junction element layer 6, which are exposed form the resist layer 8, are removed by ion beam etching, so that the read-element 6a is formed. Note that, the wafer substrate 2 is omitted in FIG. 1B and the following drawings.
In FIG. 1C, an insulating film 10, which coats a surface of the lower shielding layer 4 and side faces of the read-element 6a, is formed. Then, the hard bias film 12 is formed on the insulating film 10 by sputtering. The outer edges 12a of the hard bias film 12 in the plane-direction are defined by the specific area or the resist layers 8b (the tunnel junction element 6), so that they are outwardly projected from outer edges of the upper shielding layer.
Next, as shown in FIG. 1D, the resist layer 8 is removed, and another resist layer 13 is newly formed on the read-element 6a and the hard bias film 12, then the tunnel junction element layer 6 except the exposed read-element 6a is removed by etching.
In FIG. 1E, the resist layer 13 is removed, and a separating layer 14 is formed on the read-element 6a and the hard bias film 12.
Successively, the upper shielding layer is formed on the separating layer 14. A process for forming the upper shielding layer will be explained.
Firstly, as shown in FIG. 2F, an electric conductive layer 15 is formed on the separating layer 14. Then, a resist pattern 17 is formed on the electric conductive layer 15 except the area 19, in which the upper shielding layer will be formed.
Note that, as described above, the area 19 is smaller than the specific area, in which the hard bias film is formed, so as to outwardly project the outer edges 12a of the hard bias film 12 in the plane-direction from the outer edges of the upper shielding layer in the same direction. Namely, the resist pattern 17 is formed so as to form the upper shielding layer in the area enclosed by the outer edges 12a of the hard bias film 12.
In FIG. 2G, the upper shielding layer 16 is formed on a part of the electric conductive layer 15, which is exposed from the resist pattern 17, by plating with using the electric conductive layer 15 as an electric power feeding layer. Then, the resist pattern 17 is removed.
In FIG. 2H, parts of the electric conductive layer exposed by removing the resist pattern 17 and parts of the hard bias film 12, which are outwardly projected from the outer edges 16a of the upper shielding layer 16 in the plane-direction, are removed by an etching process, in which the upper shielding layer 16 is used as an etching mask.
Further, as shown in FIG. 2I, an insulating layer 18 is formed on the both sides of the upper shielding layer 16 and the hard bias film 12.
Note that, in FIGS. 2H and 2I, the electric conductive layer 15 formed on the separating layer 14 and the upper shielding layer 16 are shown as one layer 16.
In the production method of the present embodiment, as shown in FIGS. 1C and 1D, the hard bias film 12 is firstly formed, and the outer edges 12a of the hard bias film 12 in the plane-direction are outwardly projected from the outer edges 16a of the upper shielding layer 16 in the plane-direction. Then, as shown in FIGS. 2G and 2H, the upper shielding layer 16, and the projected parts of the hard bias film 12 by the etching process, in which the upper shielding layer 16 is used as the etching mask. Therefore, the outer edges 12b of the hard bias film 12, which has been etched, and the outer edges 16a of the upper shielding layer 16 can be highly precisely coincided.
With above described method, the upper shielding layer 16 can be formed on the flat hard bias film 12 having no step-shaped parts, and no step-shaped parts are formed by displacement of the outer edges 12b of the hard bias film 12 and the outer edges 16a of the upper shielding layer 16. By forming the upper shielding layer 16 highly flat, forming magnetic walls in the upper shielding layer 16, which cause noises, can be prevented.
The outer edges 12b and 16a are mutually coincided; weakening the leakage magnetic field and insufficient magnetic domain control can be prevented even if the upper shielding layer is smaller than the hard bias film.
FIG. 1A-1E and FIG. 2F-2I are the partial sectional views seen from the air bearing surface of the thin film magnetic head. Further, the outer edges 12b of the hard bias film 12 and the outer edges 16a of the upper shielding layer 16 in the height-direction may be processed, as shown in FIG. 4, so as to highly precisely set positions of the outer edges in the plane-direction.
Note that, the steps shown in FIG. 2G-2I may be replaced with the steps shown in FIG. 3G-3I.
In FIG. 3G, the upper shielding layer 16 is formed by plating. This state is the same as that shown in FIG. 2G.
In FIG. 3H, parts of the exposed electric conductive layer 15, the hard bias film 12 and the lower shielding layer 4, which are outwardly projected the outer edges 16a of the upper shielding layer 16 in the plane-direction, are removed by the etching process, in which the upper shielding layer 16 is used as the etching mask.
Further, as shown in FIG. 3I, an insulating layer 20 is formed on the outer sides of the upper shielding layer 16, the hard bias film 12 and the lower shielding layer 4. With this step, positions of outer edges 4a of the lower shielding layer 4 can be coincided with the outer edges 12b and 16a of the hard bias film 12 and the upper shielding layer 16.
Note that, in FIGS. 3H and 3I too, the electric conductive layer 15 formed on the separating layer 14 and the upper shielding layer 16 are shown as one layer 16.
With this structure, the thin film magnetic head has the same functions.
The invention may be embodied in other specific forms without departing from the spirit of essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Patent Application
20080002307
