Source: http://www.google.com/patents/US5633771?dq=7800613
Timestamp: 2013-12-12 00:43:16
Document Index: 583904127

Matched Legal Cases: ['art 14', 'art 14', 'art 14', 'art 24', 'art 24', 'art 24', 'art 14', 'art 45', 'art 45', 'art 45', 'art 45', 'art 45', 'art 45', 'art 45']

Patent US5633771 - Magnetoresistance effect type head and separate recording-reproducing type ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Advanced Patent Search | Sign inAdvanced Patent SearchPatentsA magnetoresistance effect type head comprises a magnetoresistance effect film having a pair of leads connected thereto and possessing a magnetic field responding part and a pair of upper and lower shield layers having a magnetoresistance effect type head satisfies the relations, W.sub.s &lt;W.sub.r...http://www.google.com/patents/US5633771?utm_source=gb-gplus-sharePatent US5633771 - Magnetoresistance effect type head and separate recording-reproducing type magnetic headPublication numberUS5633771 APublication typeGrantApplication numberUS 08/314,508Publication dateMay 27, 1997Filing dateSep 28, 1994Priority dateSep 29, 1993Fee statusLapsedAlso published asUS6056996, US6115216, US6362940Publication number08314508, 314508, US 5633771 A, US 5633771A, US-A-5633771, US5633771 A, US5633771AInventorsAkio Hori, Naoyuki Inoue, Hitoshi Iwasaki, Atsuhito Sawabe, Hiroaki YodaOriginal AssigneeKabushiki Kaisha ToshibaExport CitationBiBTeX, EndNote, RefManPatent Citations (8), Referenced by (27), Classifications (17), Legal Events (8) External Links: USPTO, USPTO Assignment, EspacenetMagnetoresistance effect type head and separate recording-reproducing type magnetic headUS 5633771 AAbstract A magnetoresistance effect type head comprises a magnetoresistance effect film having a pair of leads connected thereto and possessing a magnetic field responding part and a pair of upper and lower shield layers having a magnetoresistance effect type head satisfies the relations, W.sub.s &lt;W.sub.r and T.sub.r &lt;W.sub.r, wherein W.sub.s stands for the width of the surface of the upper shield layer facing the magnetoresistance effect film, W.sub.r for the distance between the pair of leads, and T.sub.r for the width of the magnetic field responding part of the magnetoresistance effect film. The magnetic field responding part of the magnetoresistance effect film is formed as of the remainder of the MR film region whose magnetic moment is fixed outside the end part of the upper shield layer facing the MA film. The magnetic field responding part is otherwise formed of a protruding part of the magnetoresistance effect film extended in the direction of the surface facing the medium. As a result, linear resolution suitable for a system having such high recording density as exceeds the order of Gb/inch.sup.2 of planar recording density is obtained. Further, a narrow track suitable for a system of high recording density can be produced accurately.
What is claimed is: 1. A magnetoresistance effect type head comprising:a substrate; a lower shield layer formed on the substrate; a lower magnetic gap-forming insulating film formed on the lower shield layer; a magnetoresistance effect element provided on the lower magnetic gap-forming insulating film,the magnetoresistance effect element comprising: a magnetoresistance effect film formed on the lower magnetic gap-forming insulating film, the magnetoresistance effect film having end portions separated by a center portion functioning as a magnetic field responding part; respective hard magnetic or antiferromagnetic films formed on the end portions of the magnetoresistance effect film, with a distance therebetween essentially having a value of Tr, and substantially aligned with the magnetic field responding part of the magnetoresistance effect film; and respective leads formed on the hard magnetic or antiferromagnetic films, the leads being disposed with a distance of Wr therebetween, an upper magnetic gap-forming insulating film formed over the magnetoresistance effect element, an insulating layer formed on the upper magnetic gap-forming insulating film to insulate the leads, the insulating layer providing a trench having a bottom surface which is an exposed surface of the upper magnetic gap-forming insulating film and having a bottom width of Ws, and an upper shield layer disposed to fill the trench of the insulating layer, wherein the relation of Tr&lt;Ws&lt;Wr is satisfied. 2. The magnetoresistance effect type head according to claim 1, wherein the lower and upper magnetic gap-forming insulating films have a thickness of not more than 0.1 μm.
3. A magnetoresistance effect type head comprising:a substrate; a lower shield layer formed on the substrate; a lower magnetic gap-forming insulating film formed on the lower shield layer; a magnetoresistance effect element provided on the lower magnetic gap-forming insulating film, the magnetoresistance effect element comprising: a magnetoresistance effect film formed on the lower magnetic gap-forming insulating film, the magnetoresistance effect film comprising a first magnetic layer, a non-magnetic layer formed on the first magnetic layer, and a second magnetic layer formed on the non-magnetic layer, the magnetoresistance effect film having end portions separated by a center portion functioning as a magnetic field responding part; and respective leads formed on the end portions of the magnetoresistance effect film, the leads being disposed with a distance of Wr therebetween,wherein the magnetoresistance effect element is recessed from a surface facing a medium except a protruding part of the first magnetic layer, the protruding part being extended in the direction of the surface facing the medium and having a width of Tr, an upper magnetic gap-forming insulating film formed over the magnetoresistance effect element, an insulating layer formed on the upper magnetic gap-forming insulating film to insulate the leads, the insulating layer providing a trench having a bottom surface which is an exposed surface of the upper magnetic gap-forming insulating film and having a bottom width of Ws, and an upper shield layer disposed to fill the trench of the insulating layer,wherein the relation of Tr&lt;Ws&lt;Wr is satisfied. 4. The magnetoresistance effect type head according to claim 3, wherein the protruding part functioning as the magnetic field responding part has a protruding length in the range of 0.1 to 1.0 μm.
7. The separate recording-reproducing type magnetic head according to claim 6, which satisfies the relation, T.sub.r &lt;.sub.r T.sub.w &lt;W.sub.s, wherein T.sub.w stands for a recording track width of said induction type magnetic head.
8. A magnetoresistance effect type head comprising:a substrate; a lower shield layer formed on the substrate; a lower magnetic gap-forming insulating film formed on the lower shield layer; a magnetoresistance effect element provided on the lower magnetic gap-forming insulating film, the magnetoresistance effect element comprising: a magnetoresistance effect film formed on the lower magnetic gap-forming insulating film, the magnetoresistance effect film comprising a soft magnetic layer formed on the lower magnetic gap-forming insulating film, a first magnetic layer formed on the soft magnetic layer, a non-magnetic layer formed on the first magnetic layer, and a second magnetic layer formed on the non-magnetic layer, the soft magnetic layer having a protruding part functioning as a magnetic field responding part; and respective leads formed on the end portions of the magnetoresistance effect film, the leads being disposed with a distance of Wr therebetween, wherein the magnetoresistance effect element is recessed from a surface facing a medium except the protruding part of the soft magnetic layer, the protruding part being extended in the direction of the surface facing the medium with a width of Tr, an upper magnetic gap-forming insulating film formed over the magnetoresistance effect element, an insulating layer formed on the upper magnetic gap-forming insulating film to insulate the leads, the insulating layer providing a trench having a bottom surface which is an exposed surface of the upper magnetic gap-forming insulating film and having a bottom width of Ws, and an upper shield layer disposed to fill the trench of the insulating layer,wherein the relation of Tr&lt;Ws&lt;Wr is satisfied. 9. The magnetoresistance effect type head according to claim 8, wherein the soft magnetic layer has a specific resistance of more than 100 μΩ.
In recent years, high densification of magnetic recording has advanced to the extent of realizing systems of such high levels of recording density as 500 Mb/inch.sup.2 in VTR and 200 Mb/inch.sup.2 in HDD for practical use. The demand for further densification of magnetic recording is steadily increasing in enthusiasm. This trend of the magnetic recording toward higher densification entails the essential task of reducing track width. In the case of a 200 Mb/inch.sup.2 HDD system, for example, a track width is 7 μm and the track-to-track separation is about 2 μm and, therefore, the tolerance of the track width is roughly the distance (2 μm) between the adjacent loops of the track. For the sake of attaining further exaltation of the recording density, it is necessary that the track width should be reduced to below 5 to 6 μm and the tolerance should not be more than 0.5 μm. In order to exalt the density of recording to the level of about 10 Gbits/inch.sup.2, it is expected that the track width would be required to be not more than 1 μm and the tolerance thereof to be roughly 0.1 μm. For the purpose of fulfilling these requirements, the magnetic head requires a marked improvement.
In the system of such high recording density as a recording density exceeding the order of Gb/inch.sup.2, for example, since the necessary linear resolution is equal to or smaller than the thickness of the lead of the shield type MR head, the shield type MR head of the conventional construction described above is incapable of attaining this high linear resolution. Under the circumstances, the desirability of realizing a shield type MR head possessing such a high linear resolution as is suitable for a system of high recording density exceeding the order of Gb/inch.sup.2 has been finding growing recognition.
Further, in the case of a recording density of 1 Gb/inch.sup.2, for example, the width of the shield layers 6 and 7 is desirably set at a level in the approximate range of from 3 to 5 μm because the track width is about 3 μm. Since the shield layers 6 and 7 have a thickness of about 2 μm, the MR element 3 must be formed on a protruding part measuring approximately 2 μm in height and 3 μm in width. In the case of a greater recording density of 10 Gb/inch.sup.2, it is more sternly necessary that the MR element 3 should be formed on a protruding part approximately measuring 2 μm in height and 1 μm in width. An attempt to restrain the size as of the track width of the MR element of a micron order on a substrate having such a protrusion as mentioned above merely results in seriously degrading the yield of production. If a resist 3 μm in thickness is formed on a substrate having a protruding part roughly 2 μm in height and 2 μm in width and a stripe (remnant) pattern 1 μm in width is formed on the resist, for example, the difference of the width of the MR pattern between on a mask and on a wafer will inevitably amount to -0.3 μm. Thus, the conventional shield type MR head entails the problem of imparting an abrupt jog to the substrate of the MR element and rendering accurate regulation of the track width of the MR element no longer practicable when an attempt is made to improve the recording density as described above.
Specifically, regarding the layout of the lead 2, the practice of disposing the lead 2 in such a manner that the area in which the shield 7 and the lead 2 overlap each other may be decreased to the fullest possible extent as shown in FIG. 28 is followed for the purpose of precluding the shortening between the shield and the lead. FIG. 29 shows the relation between the ratio of change of resistance of the MR element and the variation of the thickness of the lead 2 as determined with respect to varied track widths (T.sub.w) in the construction having the lead 2 disposed as described above. It is clearly noted from FIG. 29 that the dispersion of the specific resistance of the lead 2 increases and, as a result, the ratio of change of resistance abruptly decreases when the thickness of the lead 2 decreases below about 0.4 μm. In order to keep the ratio of change of resistance from decreasing extremely, therefore, it is necessary that the thickness of the lead should be not less than about 0.4 μm, and not less than about 0.2 μm at least.
SUMMARY OF THE INVENTION An object of this invention, therefore, is to provide a shield type magnetoresistance effect type head which is capable of acquiring a linear resolution suitable for a system of high recording density having a planar recording density exceeding the order of Gb/inch.sup.2, for example. A further object of this invention is to provide a shield type magnetoresistance effect type head which is capable of permitting accurate regulation of sizes such as the track width and, at the same time, acquiring a large ratio of change of resistance and, therefore, is suitable for a system of high recording density.
The first magnetoresistance effect type head of this invention is characterized by comprising a magnetoresistance effect film having a pair of leads connected thereto and possessing a magnetic field responding part, a lower shield layer disposed on the lower side of the magnetoresistance effect film through the medium of a magnetic gap forming insulating film, and an upper shield layer disposed on the upper side of the magnetoresistance effect film through the medium of another magnetic gap forming insulating film, which magnetoresistance effect type head satisfies the relations, W.sub.s &lt;W.sub.r and T.sub.r &lt;W.sub.r, wherein W.sub.s stands for the width of the surface of the upper shield layer facing the magnetoresistance effect film, W.sub.r for the distance between the pair of leads, and T.sub.r for the width of the magnetic field responding part of the magnetoresistance effect film.
In the first magnetoresistance effect type head, the leads are disposed outside the substantial opposite edges of the reproducing magnetic gap by causing the distance W.sub.r between the leads to be larger than the width W.sub.s of the surface of the upper shield layer facing the magnetoresistance effect film. Owing to this arrangement, the effect of the thickness of the leads on the length of the reproducing magnetic gap can be eliminated. As a result, the desire to decrease the gap can be realized and the linear resolution suitable for the exaltation of recording density even exceeding the order of Gb/inch.sup.2 can be attained.
Further, since the width T.sub.r of the active region of the magnetoresistance effect film is caused to be smaller than the distance W.sub.r between the leads and preferably smaller than the width W.sub.s of the surface of the upper shield layer facing the magnetoresistance effect film, the cross talk possibly induced by the decrease of the track width can be precluded and the exaltation of linear resolution can be attained by the decrease of the gap as well. In short, the decrease of the gap and the decrease of the track width can be obtained without inducing degradation of the regenerating characteristics.
FIG. 29 is a characteristic diagram showing the relation between the thickness of the leads and the ratio of change of resistance of the MR element as determined in the layout of the leads shown in FIG. 28 with respect to varied track widths (T.sub.w).
FIG. 1 and FIG. 2 are diagrams showing the construction of a separate recording-reproducing type magnetic head according to one embodiment of this invention. FIG. 1 is a front view of the construction taken from the surface opposite a medium and FIG. 2 is a cross section taken through FIG. 1 along the line A--A. In these diagrams, 11 stands for a substrate which is made as of Al.sub.2 O.sub.3 O.sub.3. On this substrate 11 is formed a lower shield layer 12 which is made of such a soft magnetic material as NiFe alloy or an amorphous alloy like CoZrNb. On the lower shield layer 12, a magnetoresistance effect film (MR film) 14 is formed through the medium of a lower regenerating magnetic gap layer 13 made of an insulating film such as of Al.sub.2 O.sub.3.
An anisotropic magnetoresistance effect film made as of Ni.sub.80 Fe.sub.20 and allowed to offer such electric resistance as varies with the angle formed between the direction of electric current and the magnetizing moment of the magnetic material layer, a spin valve film made as of a Co.sub.90 Fe.sub.10 /Cu/Co.sub.90 Fe.sub.10 laminate film having the laminate of a magnetic film and a non-magnetic film and showing the so-called spin valve effect of offering such electric resistance as varies with the angle formed between the directions of magnetization of the magnetic material layers, or a artificial lattice film manifesting gigantic magnetoresistance effect, for example, may be cited as a concrete example of the MR film 14 mentioned above.
On the MR film 14, a pair of magnetically fixed films 15 made of a hard magnetic film or an antiferromagnetic film as of FeMn are formed in a desired shape. An opening (remnant part) between the magnetically fixed films 15 forms a magnetic field responding part 14a. In other words, the width (active area width) T.sub.r of the magnetic field responding part 14a of the MR film 14 is defined by the magnetically fixed films 15. A pair of leads 16 made as of Cu and electrically connected each to the opposite ends of the MR film 14 are formed on the magnetically fixed films 15. The MR film 14, the magnetically fixed films 15, and the leads 16 jointly form a MR element 17.
On the MR element 17 is formed an upper regenerating magnetic gap layer 18 which is made of an insulating film as of Al.sub.2 O.sub.3. Insulating layers 19 made as of SiO.sub.2 are formed further thereon. The insulating layers 19 are intended to secure dielectric strength between the leads 16 and an upper shield layer 20 and is formed so as to cover the upper surfaces of the leads 16. The upper shield layer 20 made of the same soft magnetic material as the lower shield layer 12 are formed as partly embedded in a trench 19a formed between the insulating layers 19 so that the surface thereof, opposite the medium, may assume a protruding shape extended in the direction of the upper regenerating magnetic gap layer 18. These components jointly form a shield type MR head 21 which functions as a regenerating head.
The width W.sub.s of the surface of the upper shield layer 20, opposite the MR film, is defined by the width of the trench 19a formed between the insulating layers 19. The trench 19a has the shape thereof so set that the width W.sub.s of the surface thereof, opposite the MR film, may be smaller than the distance W.sub.r between the pair of leads 16. Thus, the pair of leads 16 are disposed each outside the edges of the end parts of the surface of the upper shield layer 20 opposite the MR film. The magnetization of the MR film 14 positioned at least outside the edges of the end parts of the surface of the upper shield layer 20 opposite the MR film is attained by means of the magnetically fixed film 15 mentioned above. Actually, the pair of the magnetically fixed films 15 are so patterned that the width of the magnetic field responding part 14a of the MR film 14 (substantially the regenerating track width) T.sub.r corresponding to the distance between the pair of the magnetically fixed films 15 may be smaller than the distance W.sub.r between the leads 16 and the width W.sub.s of the surface of the upper shield layer 20 opposite the MR film.
In the shield type MR head 21 constructed as described above, the width W.sub.s of the surface of the upper shield layer 20 opposite the MR film is smaller than the distance W.sub.r between the leads 16 and the pair of leads 16 are disposed each outside the edges of the end parts of the surface thereof opposite the MR film. Owing to this arrangement, the thicknesses of the insulating layers 19 and the leads 16 permit elimination of the effect possibly exerted by the surface of upper shield layer 20 opposite the MR film on the substrate even when the insulating layers 19 for securing dielectric strength between the leads 16 and the upper shield layer 20 are formed. As a result, the substrate underlying the surface of the upper shield layer 20 opposite the MR film may be flattened to a great extent. The surface of the upper shield layer 20 opposite the MR film is not always required to be perfectly flat but may be caused to jog more or less owing to the difference of level formed in the upper surface of the MR element 17 excepting the leads 16 as shown in the diagram.
Further, since the MR film 14 positioned at least outside the edges of the opposite end parts of the surface of the upper shield layer 20 opposite the MR film, is fixed magnetically in place by the magnetically fixed layer 15, the otherwise possible occurrence of such adverse phenomena as cross talk can be precluded even when the width W.sub.s of the surface of the upper shield layer 20 opposite the MR film, is caused to be smaller than the distance W.sub.r between the leads 16 and the width W.sub.s of the upper shield layer 20 extends throughout the entire thickness thereof. As a result, the decrease of the track width can be realized without entailing such faults as degradation of the regeneration characteristics.
On the regenerating head which is formed of the shield type MR head 21 constructed as described above, the recording head formed of an induction type thin-film magnetic head 22 is formed. The upper shield layer 20 of the shield type MR head 21 serves concurrently as a lower magnetic core of the induction type thin-film magnetic head 22. On the lower magnetic core 20 furnished with a flat smooth upper surface, an upper magnetic core 24 is formed through the medium of a recording magnetic gap layer 23 which is made as of Al.sub.2 O.sub.3. Here, the upper magnetic core 24 is formed as partly embedded in a trench 25a which is formed in a trench-forming insulating layer 25 superposed on the recording magnetic gap layer 23 and made as of SiO.sub.2. The surface opposite the medium, namely the cross section of the leading end part of the upper magnetic core 24, is so shaped as to protrude in the direction of the recording magnetic gap layer 23.
Then, in the induction type thin-film magnetic head 22 which is constructed as described above, the upper shield layer 20 concurrently serving as the lower magnetic core as described above has the surface thereof opposite the medium vested with a protruding shape extended in the direction of the upper regenerating magnetic gap layer 18. It is, therefore, extremely easy to give to the protruding part 24a of the upper magnetic core 24 a width smaller than the width of the surface of the upper shield layer 20 opposite the recording magnetic gap layer 23. As a consequently, the recording track width T.sub.w can be accurately defined with the width of the protruding part 24a of the upper magnetic core 24.
Then, in the induction type thin-film magnetic head 22 of the construction described above, the width T.sub.w of the recording track which is defined by the width of the protruding part 24a of the upper magnetic core 24 is caused to be larger than the regenerating track width of the shield type MR head 21, namely the width T.sub.r of the magnetic field responding part of the MR film 14, and smaller than the width W.sub.s of the surface of the upper shield layer 20 of the shield type MR head 21 opposite the MR film. In the separate recording-reproducing type magnetic head of this invention, the dimensions T.sub.r, T.sub.w, and W.sub.s are desirably required to satisfy this relation, T.sub.r &lt;T.sub.w &lt;W.sub.s. By satisfying this requirement, the off-track characteristic of ideal grade can be stably obtained during the regeneration of a recording of high density.
First, the lower shield layer 12 of a thickness of about 1.5 μm and the lower magnetic gap layer 13 of a thickness of about 0.2 μm are formed as by the sputtering technique on the substrate 11. Further, the MR film 14 is formed by the vacuum deposition technique and the MR film 14 is patterned roughly in the shape of a ribbon as by the ion milling technique. Then, a pair of magnetically fixing films 15 and a pair of leads 16 are sequentially formed in the order mentioned in desired shapes as by the lift-off technique on the MR film 14 to complete the MR element 17 (a in FIG. 4). Further, the upper magnetic gap layer 18 of a width of about 0.2 μm and the insulating layer 19 of a width of about 0.5 μm made of SiO.sub.2 are sequentially formed in the order mentioned as by the sputtering technique (b in FIG. 4).
Then, a resist mask (not shown) is formed on the insulating layers 19. The insulating layers 19 are etched with such an etching gas as CF.sub.4 to give rise to the trench 19a which is destined to serve as a part for forming the surface of the upper shield layer 20 opposite the MR film, as shown in c in FIG. 4. Here, the width of the trench 19a which determines the width W.sub.s of the surface of the upper shield layer 20, opposite the MR film, is caused to be smaller than the distance W.sub.r between the leads 16. With respect to the suitability of the process under consideration for quantity production, the depth of the trench 19a is desired to be in the approximate range of from 0.5 to 1.0 μm. The lateral walls of the trench 19a can be formed either slightly obliquely or perpendicularly by controlling the etching conditions.
Then, the recording magnetic gap layer 23 of a thickness of about 0.3 μm and the insulating layer 25 are sequentially formed in the order mentioned as by the sputtering technique on the upper shield layer 20 which has acquired a flattened surface. Thereafter, the trenches (25a, etc.) are formed by the reactive ion etching technique in the parts of the insulating layer 25 corresponding to the front part gap and the rear part gap shown in FIG. 2. Further, a coil (not shown) is formed as by the plating technique on the insulating layer 25 and an insulating layer (not shown) is formed thereon excepting the front part gap and the rear part gap to bury the coil under the insulating layer consequently formed. Then, a magnetic material destined to form the upper magnetic core 24 is filled in the parts of the trench corresponding to the front part gap and the rear part gap and, at the same time, deposited to a desired thickness as by the sputtering technique (a in FIG. 5). This filling of the magnetic material in the trench is desired to be carried out by the collimation spattering technique. The width of the trench 25a which determines the recording track width T.sub.w is so set as to satisfy the relation of magnitude, W.sub.s &gt;T.sub.w &gt;T.sub.r, as described above.
Incidentally, in the separate recording-reproducing type magnetic head 29 of the embodiment described above, the size T.sub.r corresponding to the regenerating track width, the recording track width T.sub.w, and the width W.sub.s of the surface of the upper shield layer 20 opposite the MR film are required to be so set as to satisfy the relation, T.sub.r &lt;T.sub.w &lt;W.sub.s. When this requirement is satisfied, the step for flattening the surface of the upper shield layer 20 of the shield type MR head 21 may be omitted as shown in FIG. 6, for example. To be specific, if the step for flattening the surface of the upper shield layer 20 is omitted, the satisfaction of this relation, T.sub.w &lt;W.sub.s, will enable the linearity of the recording magnetic gap to be maintained substantially throughout the entire recording track width and the satisfaction of this relation, T.sub.r &lt;T.sub.w, will enable the off-track characteristic to be retained ideally during the course of regeneration. In the process of production described above, the item 3σ can be machined accurately within 0.1 μm even when the recording track width is not more than 1 μm because the recording track width T.sub.w is definitely fixed by subjecting the insulating layer 25 made of such a material as SiO.sub.2 which is suitable for fine machining and prepared in a state having a relatively small difference of level to the reactive ion etching technique.
The separate recording-reproducing type magnetic head 31 of the present embodiment, similarly to the embodiment described previously except for the construction just mentioned, causes the width W.sub.s of the surface of the upper shield layer 20 opposite the MR film to be smaller than the distance W.sub.r between the leads 16 and utilizes the magnetically fixing film 15 for magnetically fixing the MR film 14 positioned at least outside the edges of the end parts of the surface of the upper shield layer 20 opposite the MR film. Further, it requires the width of the magnetic field responding part 14a of the MR film 14 (substantial width of the regenerating track) to be smaller than the width W.sub.s of the surface of the upper shield layer 20 opposite the magnetoresistance effect film. Incidentally, the upper magnetic core 24 may be furnished with a protruding shape relative to the recording magnetic gap layer 23 similarly to the embodiment described previously.
FIG. 12 is a perspective view partially showing the construction of the MR head of the present embodiment and FIG. 13 is a front view of the MR head taken from the side opposite the medium. On a substrate 41, a lower shield layer 42 and a lower regenerating magnetic gap layer 43 are sequentially formed in the order mentioned in the same manner as in the embodiments described above. On the lower regenerating magnetic gap layer 43, a spin valve film having a three-layer laminate construction of first magnetic film (such as, for example, Co.sub.90 Fe.sub.10 film) 45/nonmagnetic film (such as, for example, Cu film) 46/second magnetic film (such as, for example, Co.sub.90 Fe.sub.10 film) 47 is formed as a MR film 44.
A pair of leads 48 are severally formed on the second magnetic film 47 which is recessed from the surface opposite the medium. These components jointly form a MR element 49. Thus, the protruding part 45a of the first magnetic film 45 exclusively responds to an external magnetic field (signal magnetic field) because the MR element 49 is recessed from the surface opposite the medium except for the protruding part 45a of the first magnetic film 45. As a result, the protruding part 45a of the first magnetic film 45 constitutes a magnetic field responding part and the width T.sub.r of the magnetic field responding part forms the width of the protruding part 45a.
The width W.sub.s of the surface of the upper shield layer 52 opposite the MR film is defined by the width of the trench 51a which is formed, similarly to the various embodiments described above, in the insulating layers 51. The trench 51a is so shaped that the width W.sub.s of the surface opposite the MR film may be smaller than the distance W between the leads 48. In other words, the pair of leads 48 are disposed each outside the edges of the end parts of the surface of the upper shield layer 52 opposite the MR film. Further, the first magnetic film 45 is so patterned that the width T.sub.r of the magnetic field responding part (the width of the protruding part 45a) may be smaller than the distance W.sub.r between the leads 48 and the width W.sub.s of the surface of the upper shield layer 52 opposite the MR film.
In the shield type MR head 53 which is constructed as described above, the width W.sub.s of the surface of the upper shield layer 52 opposite the MR film is caused to be smaller than the distance between the leads 48 and the pair of leads 48 are disposed each outside the edges of the end parts of the surface opposite the MR film. As a result, the substrate underlying the surface of the upper shield layer 52 opposite the MR film may be flattened to a notable extent similarly to the various embodiments described above. This is because the effect which the thicknesses of the insulating layers 51 and the leads 48 exerts on the substrate underlying the surface of the upper shield layer 52, opposite the MR film, can be eliminated in spite of the formation of the insulating layers 51 which secure dielectric strength between the leads 48 and the upper shield layer 52. Thus, the dielectric strength between the leads 48 and the upper shield layer 52 is secured by the formation of the insulating layers 51, and the insulation between the MR film (spin valve film) 44 and the upper shield layer 52 in the magnetic field responding part of the MR film (spin valve film ) 44 is attained by the upper regenerating magnetic gap layer 50 of a small thickness. This fact implies that the decrease of the gap to such a small size as not more than 0.1 μm, for example, can be attained herein.
Further, the magnetic field responding part is formed of the protruding part 45a of the first magnetic film 45 and the other part of the MR film 44 is recessed from the surface opposite the medium and the width T.sub.r of the magnetic field responding part is caused to be smaller than the distance W.sub.r between the leads 48 and the width W.sub.s of the surface of the upper shield layer 52 opposite the MR film as well. Even when the width W.sub.s of the surface of the upper shield layer 52 opposite the MR film is caused to be smaller than the distance W.sub.r between the leads 48 and this width W.sub.s of the upper shield layer 52 is caused to extend throughout the entire direction of its thickness, therefore, such defects as the occurrence of noise due to leakage of a magnetic flux from adjacent loops of track or from a motor can be prevented and, as a result, the decrease of track width can be realized without entailing degradation of the regenerating characteristic.
FIG. 14 shows the results of a test performed to determine the relation between the length L of protrusion of the protruding part 45a destined to form the magnetic field responding part and the probability of occurrence of Barkhausen noise where the width T.sub.r of the magnetic field responding part was 2 μm and the distance W.sub.r between the leads was 5 μm. In this case, the isolation of the domain of the first magnetic film 45 was attained by disposing a CoPt film 40 nm in thickness at a position directly below the lead 48. It is clearly noted from FIG. 14 that substantial elimination of Barkhausen noise is attained by decreasing L to below 1.0 μm. Since the accuracy of alignment of the stepper is roughly within .+-1 μm when the lead 48 is also recessed as shown in FIG. 12, it is theoretically inferred that the lead 48 will be completely recessed from the surface opposite the medium when L is 0.1 or over. Actually, L is desired to be not less than about 0.23 μm (={(0.1).sup.2 +(0.2).sup.2 }.sup.0.5) in due consideration of the error of the polishing work which is about .+-2 μm. Thus, L is desired to be in the range of from 0.1 to 1.0 μm, practically in the range of from 0.23 to 1.0 μm. L is desired to exceed roughly the distance between the MR film (spin valve film) 44 and the upper shield layer 52 in the part of the lead 48, for this size allows prevention of the noise due to the disturbance of a magnetic field in the z direction.
As shown in FIG. 17, for example, a resist 62 is formed on a trench-forming insulating layer 61 made as of SiO.sub.2 (a in FIG. 17) and the insulating layer 61 is subjected to a chemical dry etching (CDE) treatment using a CF.sub.4 gas (b in FIG. 17). This CDE is allowed to proceed to halfway along the thickness of the insulating layer 61 and then followed by a reactive ion etching (RIE) treatment to complete a trench 61a (c in FIG. 17). By the joint use of CDE and RIE in the manner described above, the trench 61a can be formed in a two-step tapered cross section.
Then, the resist 61 is removed (d in FIG. 17) and a magnetic material 63 such as of CoZrNb is filled in the trench 62a as by the sputtering technique (e in FIG. 17). In this case, a taper 63a can be imparted to the magnetic material 63 as shown in e in FIG. 17 by conferring a bias of about 0.1 W/cm.sup.2 on the sputtering. By flattening the surface of the magnetic material 63 thereafter, a magnetic material layer 64 completely embedded in the trench 61a and furnished with the two-step tapered cross section is obtained.
FIG. 18 shows another example of the embedding work. In the same manner as in the example of production cited above, the resist 62 is formed on the insulating layer 61 made as of SiO.sub.2 and then the RIE treatment is performed by the use of the CHF.sub.3 gas so as to cool the substrate to about 273K and, at the same time, etch the insulating layer 61 to halfway along the thickness thereof. In this case, the taper is imparted by cooling the substrate to about 273K thereby forming a deposit 65 on the lateral walls of the etched cavity (a in FIG. 18). Then, the RIE treatment as with CF.sub.4 gas is performed to etch the insulating layer 60 vertically this time to complete the trench 61a of a two-step tapered cross section (b in FIG. 18).
Also in this method of production of the magnetic material layer 64, the magnetic material layer 64 can be formed can be formed as embedded in a perfect state without entailing the occurrence of such defects as gross porosity. When films of two kinds of material such as, for example, SiO.sub.2 and Si which have different etching properties are superposed in the order mentioned and the resultant laminate is used as the insulating layer 61, the magnetic material layer 64 furnished with the same two-step tapered cross section will be obtained if the step of operation shown in b in FIG. 18 or c in FIG. 18, for example, is omitted.
FIG. 19 depicts another example of the embedding operation. In the same manner as in the example of production cited above, the resist 61 is formed on the insulating layer 61 made as of SiO.sub.2 and then the RIE treatment as with CF.sub.4 gas is carried out to etch the insulating layer 61 to halfway along the thickness thereof (a in FIG. 19). Subsequently, the RIE treatment as with the CHF.sub.3 gas is carried out to cool the substrate to about 0 layer 61 in a tapered cross section while forming the deposit 65 on the lateral walls of the etched cavity. Consequently, the trench 61a furnished with a two-step tapered cross section is formed (b in FIG. 19).
Also in this method of production of the magnetic material layer 64, the magnetic material layer 64 can be formed as embedded in a perfect state without entailing the occurrence of such defects as gross porosity. When films of two kinds of material such as, for example, SiO.sub.2 and Si which have different etching properties are superposed in the order mentioned and the resultant laminate is used as the insulating layer 61, the magnetic material layer 64 furnished with the same two-step tapered cross section will be obtained if the step of operation shown in b in FIG. 19 or c in FIG. 19, for example, is omitted.
In the magnetic material layer 64 furnished with such a two-step tapered cross section as described above, the effect of preventing the occurrence of gross porosity can be brought about in the process of production shown in FIG. 18, for example, by confining the upper tapering angle φ within the range, 0 degree&lt;φ&lt;80 degrees, as shown in FIG. 20. In the process of production shown in FIG. 19, the effect of preventing the occurrence of gross porosity can be brought about by confining the lower taping angle φ within the range, 20 degrees&lt;φ&lt;80 degrees, as shown in FIG. 21. Then, in a magnetic material layer 66 furnished with a three-step tapered cross section as shown in FIG. 22, the effect of preventing the occurrence of gross porosity is obtained by confining the lower tapering angle φ within the range, 20 degrees&lt;φ&lt;88 degrees, and causing the intermediate tapering angle θ and the upper tapering angle Ψ to satisfy the relations, φ&lt;θ and Ψ&lt;θ, respectively. The effect of preventing the occurrence of gross porosity is further higher when the relation, Ψ&lt;φ, is satisfied.
FIG. 23 is a partially sectioned perspective view showing the construction of a magnetoresistance effect type head according to the embodiment of this invention. A trench-forming insulating layer 73 made as of SiO.sub.2 is formed on an insulating layer made as of Al.sub.2 O.sub.3 and formed on a substrate 71. A lower shield layer 74 made of such a soft magnetic material as NiFe alloy or Co-based amorphous alloy is formed as embedded in a trench 73a which is formed in the insulating layer 73.
A magnetoresistance effect film 76 such as, for example, an anisotropic magnetoresistance effect film made as of Ni.sub.80 Fe.sub.20, a spin valve film formed as of a Co.sub.90 Fe.sub.10 /Cu/Co.sub.90 Fe.sub.10 laminate film, or a artificial lattice film is formed through the medium of a lower regenerating magnetic gap layer 75 formed of an insulating film as of Al.sub.2 O.sub.3 on the lower shield layer 74. This magnetoresistance effect film 76 is patterned in a prescribed shape and has a pair of leads 77 as of Cu connected each to the opposite ends thereof. These components jointly form a MR element 78.
An upper regenerating magnetic gap layer 79 formed of an insulating film as of Al.sub.2 O.sub.3 is formed on the MR element 78 and a trench-forming insulating layer 81 made as of SiO.sub.2 is formed further thereon through the medium of an etching stopper layer 80 made as of C. An upper shield layer 82 is formed as embedded in a trench 81a which is formed in the insulating layer 81. As a result, a shield type MR head 83 which is destined to function as a regenerating head is formed.
First, the insulating layer 72 having a thickness of about 10 μm and made as of Al.sub.2 O.sub.3 and the trench-forming insulating layer 73 having a thickness of about 2 μm and made as of SiO are formed in the order mentioned on the substrate 71. Then, a resist mask (not shown) is formed on the trench-forming insulating layer 73 and then the insulating layer 73 is etched with the etching gas as of CF.sub.4 to form the trench 73a which corresponds to a part for the formation of the lower shield layer 74 as shown in a in FIG. 24. By suitably selecting the etching conditions in this case, the lateral walls of the trench 73a may be slightly tapered or extended perpendicularly.
Then, the lower regenerating magnetic gap layer 75 having a thickness of about 0.1 μm and formed of an insulating film as of Al.sub.2 O.sub.3 and the magnetoresistance effect film 76 formed of an anisotropic magnetoresistance effect film or a spin valve film are formed in the order mentioned on the lower shield layer 74. This magnetoresistance effect film 76 is patterned in a prescribed shape and the pair of leads 77 made as of Cu are formed at the opposite ends of the patterned magnetoresistance effect film 76 as by the lift-off technique to give rise to the MR element 78 (a in FIG. 25).
Then, the MR element 87 is covered with the upper regenerating magnetic gap layer 79 having a thickness of about 0.1 μm and formed of an insulating film as of Al.sub.2 O.sub.3, the etching stopper layer 80 having a thickness of about 0.05 μm and made as of C is formed, and further the trench-forming insulating layer 81 having a thickness of about 2 μm and made as of SiO.sub.2 are formed. A trench 81a is formed by etching the trench-forming insulating layer 81 in the same manner as in the process for the formation of the lower shield layer 74. Further, the etching stopper layer 80 at the bottom of the trench 81a is removed by the CDE treatment using 0.sub.2 or the RIE treatment. Thereafter, the upper shield layer 82 is formed by filling an amorphous soft magnetic alloy in the trench 81a in the same manner as in the process for the formation of the lower shield layer 74 and removing the unnecessary part of the filled alloy as by the polishing treatment (b in FIG. 25). The shield type MR head 83 of the present example is obtained as described above.
Further, since the surface of the substrate of the MR element 78, namely the upper surface of the lower shield layer 74 including the upper surface of the insulating layer 73, can be flattened accurately within 3 nm by R.sub.max, the specific resistance of the magnetoresistance effect film 86 having a thickness in the approximate range of from 10 to 30 nm and formed as of Ni.sub.80 Fe.sub.20 can be confined within about 20 μΩcm and the ratio of change of resistance can be increased. For example, when the magnetoresistance effect film 76 made of Ni.sub.80 Fe.sub.20 is used in the construction of the seventh embodiment described above, it shows a ratio of change of resistance increased to about 3.5% as compared with the conventional shield type MR head which shows a ratio of change of resistance of about 2%.
In order to produce a separate recording-reproducing magnetic head by forming a recording head formed of an induction type thin-film magnetic head on a regenerating head formed of such a shield type MR head as described above, an upper magnetic core 85 is formed by an ordinary method through the medium of a recording magnetic gap layer 84 made as of Al.sub.2 O.sub.3 on the upper shield layer 82 concurrently serving as the lower magnetic core of the recording head. In the diagram, 86 stands for a projecting film made as of Al.sub.2 O.sub.3. FIG. 26 omits such components as the recording coil.
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2008REMIMaintenance fee reminder mailedSep 22, 2004FPAYFee paymentYear of fee payment: 8Sep 28, 2000FPAYFee paymentYear of fee payment: 4Jun 16, 1998CCCertificate of correctionNov 16, 1994ASAssignmentOwner name: KABUSHIKI KAISHA TOSHIBA, JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:YODA, HIROAKI;SAWABE, ATSUHITO;IWASAKI, HITOSHI;AND OTHERS;REEL/FRAME:007204/0762Effective date: 19941026Nov 16, 1994AS02Assignment of assignor's interestOwner name: HORI, AKIOwner name: INOUE, NAOYUKIOwner name: IWASAKI, HITOSHIOwner name: KABUSHIKI KAISHA TOSHIBA 72, HORIKAWA-CHO SAIWAI-KEffective date: 19941026Owner name: SAWABE, ATSUHITOOwner name: YODA, HIROAKIRotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google