Source: http://www.google.com/patents/US6056996?dq=system+for+measuring+web+traffic&ei=Lg8FT__TIIr-sQKzxaGRCg
Timestamp: 2015-05-06 06:32:43
Document Index: 664843750

Matched Legal Cases: ['Application No. 3', 'art 14', 'art 14', 'art 24', 'art 20', 'art 20', 'art 20', 'art 45']

Patent US6056996 - Magnetoresistance effect type head and separate recording-reproducing type ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »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 film nipped therebetween through the medium of a magnetic...http://www.google.com/patents/US6056996?utm_source=gb-gplus-sharePatent US6056996 - Magnetoresistance effect type head and separate recording-reproducing type magnetic headAdvanced Patent SearchPublication numberUS6056996 APublication typeGrantApplication numberUS 09/358,465Publication dateMay 2, 2000Filing dateJul 22, 1999Priority dateSep 29, 1993Fee statusLapsedAlso published asUS5633771, US6115216, US6362940Publication number09358465, 358465, US 6056996 A, US 6056996A, US-A-6056996, US6056996 A, US6056996AInventorsHiroaki Yoda, Atsuhito Sawabe, Hitoshi Iwasaki, Naoyuki Inoue, Akio HoriOriginal AssigneeKabushiki Kaisha ToshibaExport CitationBiBTeX, EndNote, RefManPatent Citations (9), Referenced by (7), Classifications (21), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetMagnetoresistance effect type head and separate recording-reproducing type magnetic head
US 6056996 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 film nipped therebetween through the medium of a magnetic gap-forming insulating film. This magnetoresistance effect type head satisfies the relations, Ws <Wr and Tr <Wr, wherein Ws stands for the width of the surface of the upper shield layer facing the magnetoresistance effect film, Wr for the distance between the pair of leads, and Tr 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/inch2 of planar recording density is obtained. Further, a narrow track suitable for a system of high recording density can be produced accurately.
1. A method for manufacturing a recording-reproducing magnetic head comprising the steps of:depositing a lower shield layer on a substrate; forming a lower magnetic gap-forming layer on the lower shield layer; forming a magnetoresistance effect element having a magnetic responding part on the lower magnetic gap-forming layer; forming an upper magnetic gap-forming layer over the magnetoresistance effect element; forming a first insulating layer on the upper magnetic gap-forming layer; forming a first trench in the first insulating layer to expose a flat surface region of the upper magnetic gap-forming layer; forming an upper shield layer on the first insulating layer while filling a magnetic material of the upper shield layer into the first trench, thereby forming a first protruding part of the upper shield layer extending to the upper magnetic gap-forming layer; forming a second protruding part on the upper shield layer by milling the upper shield layer, thereby forming the upper shield layer with a second protruding part protruding away from the first insulating layer; forming a recording magnetic gap layer having a substantially uniform thickness on the upper shield layer with the second protruding part; forming a second insulating layer on the recording magnetic gap layer; forming a second trench in the second insulating layer at a position opposed to the second protruding part and separated therefrom by the recording magnetic gap layer; and forming an upper magnetic core having a third protruding part formed by filling a magnetic material of the upper magnetic core in the second trench so that the lower magnetic core is opposed to the upper magnetic core with the recording magnetic gap layer therebetween, the third protruding part contacting the recording magnetic gap layer at a flat surface thereof. 2. The method of claim 1, wherein the step of forming the upper magnetic core includes forming the third protruding part with a tapered cross section such that the width of cross section of the third protruding part decreases toward the recording magnetic gap layer.
3. The method of claim 2, wherein the step of forming the second protruding part of the upper shield layer forms the second protruding part with a cross section such that the width of cross section of the second protruding part decreases toward the recording magnetic gap layer.
4. The method of claim 1, wherein the third protruding part is formed with a two-step tapered cross section comprising an upper taper and a lower taper, the upper taper has an angle of not more than 80 degrees with a plane parallel to the flat surface of the recording magnetic gap layer.
This is a division of application Ser. No. 08/780,328, filed Jan. 8, 1997, which is a division of application Ser. No. 08/314,508, filed Sep. 28, 1994, U.S. Pat. No. 5,633,771. The contents of these applications being relied upon and incorporated by reference herein.
A method for defining such a narrow track-width of heads has been reported, by which magnetic core in air bearing surface is focused ion etched (refer to Japanese Patent Laid-Open Application No. 3-296907). This method, however, is handicapped greatly in the capacity for mass production because the method requires processing of the magnetic heads one by one and the FIB etching technique itself has a very poor throughput, though the method is capable of infallibly producing an accurate track width.
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 Wr between the leads to be smaller than the width Ws 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/inch2 can be attained.
The first separate recording-reproducing type magnetic head enables a system of high recording density to produce desired recording-and reproducing operations stably because it uses a reproducing head formed of the aforementioned first magnetoresistance effect type head and a recording head formed of an induction magnetic head. The induction magnetic head used herein allows the decrease of track width to be realized with high accuracy because the surface of the magnetic core facing the medium is so shaped as to possess a protruding part extended in the direction of the recording magnetic gap. Further, since the axis of easy magnetization of the protruding part of the magnetic core is easily aligned in the direction of the track width in this case, the axis of easy magnetization can be parallelled with the direction of the track width enough to obtain ample high-frequency permeability stably even when the track width is decreased.
FIGS. 4a, b, c, d and e are a cross section showing part of a process for the production of the separate recording-reproducing type magnetic head shown in FIG. 1.
FIGS. 5a and b are a cross section showing the part of the process for the production of the separate recording-reproducing type magnetic head shown in FIG. 1, subsequent to the part of the process shown in FIG. 4.
FIGS. 7a and b are a cross section showing the essential part of the construction and the production process of a separate recording-reproducing type magnetic head according to the second embodiment of this invention.
FIGS. 10a, b and c are a cross section showing the essential part of a process for the production of the separate recording-reproducing type magnetic head shown in FIG. 8.
FIGS. 17a, b, c, d, e and f are a cross section showing a process for the production of a completely embedded magnetic material layer.
FIG. 18a, b, c, d and e are a cross section showing another process for the production of a completely embedded magnetic material layer.
FIG. 19 is a cross section showing yet another process for the production of a completely embedded magnetic material layer.
FIGS. 24a, b and c are a cross section showing part of a process for the production of the MR head shown in FIG. 23.
FIGS. 25a and b are a cross section showing the part of the process for the production of the MR head shown in FIG. 23, subsequent to the part of the process shown in FIG. 24.
On the MR film 14, a pair of magnetically fixed film 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) Tr 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 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 Al2 O3. 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 SiO2. 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 gas layer 23.
Then, in the induction type thin-film magnetic head 22 of the construction described above, the width Tw 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 Tr of the magnetic field responding part of the MR film 14, and smaller than the width Ws 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 Trr, Tw, and Ws are desirably required to satisfy this relation, Tr <Tw <Ws. 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 spattering 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 SiO2 are sequentially formed in the order mentioned as by the spattering technique (b in FIG. 4).
Now, part of a magnetic material which is destined to form the upper shield layer 20 is embedded in the trench 19a as by the spattering technique and a magnetic material is subsequently superposed thereon to give rise to the upper shield layer 20 of a thickness of about 2 μm concurrently serving as a lower magnetic core (d in FIG. 4). In this case, the cavity in the trench 19a is desired to be filled out by the collimation spattering technique. Thereafter, the surface of the upper shield layer 20 is flattened by the operation of polishing back or etching back (e in FIG. 4). Incidentally, this step for flattening the surface of the upper shield layer 20 may be omitted as will be described specifically below.
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 spattering 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 spattering 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 Tw is so set as to satisfy the relation of magnitude, Ws >Tw >Tr, as described above.
Incidentally, in the separate recording-reproducing type magnetic head 29 of the embodiment described above, the size Tr corresponding to the regenerating track width, the recording track width Tw, and the width Ws of the surface of the upper shield layer 20 opposite the MR film are required to be so set as to satisfy the relation, Tr<T w <Ws. 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, Tw <Ws, 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, Tr <Tw, will enable the off-track characteristic to be retained ideally during the course of regeneration. In the process of production described above, the item 3a 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 Tw is definitely fixed by subjecting the insulating layer 25 made of such a material as SiO2 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 magnetic head 29 of this embodiment, particularly the induction type thin-film magnetic head 22 thereof, has formed inside the trench 25a inserted in the insulating layer 25 a three-layer construction formed of a magnetic material layer 30, the recording magnetic gap layer 23, and the upper magnetic core 24. Specifically, in the process for the production of the separate recording-reproducing type magnetic head shown in FIG. 4 and FIG. 5, the insulating layer 25 is formed prior to the formation of the recording magnetic gap layer 23 and then the trenches (including the trench 25a) corresponding to the front part gap and the rear part gap are formed. Inside these trenches (including the trench 25a), the magnetic material layer 30 destined to form part of the upper shield layer 20 serving concurrently as the lower magnetic core is formed in an embedded state and then the recording magnetic gap layer 23 is formed (a in FIG. 7). Subsequently, a magnetic material is embedded in the remaining parts of the trenches (including the trench 25a) and, at the same time, deposited therein to a desired thickness as by the spattering technique and the magnetic material layer is patterned to give rise to the upper magnetic core 24 (b in FIG. 7).
Specifically, in the process for the production of the separate recording-reproducing type magnetic head shown in FIG. 4 and FIG. 5, first the magnetic material layer destined to form the upper shield layer 20, concurrently serving as a lower magnetic core, is formed and then a protruding part 20a is formed on the surface of the magnetic material layer as by the ion milling technique (a in FIG. 10). Then, on the upper shield layer 20 now possessing the protruding part 20a, the recording magnetic gap layer 23 and the insulating layer are sequentially formed in the order mentioned as by the spattering technique (b in FIG. 10). Then, the trenches (including the trench 25a) are formed in the insulating layer 25 at the positions of the protruding part 20a of the upper shield layer 20, namely in the part corresponding to the front part gap and the part corresponding to the rear part gap 23b (c in FIG. 10). Thereafter, the separate recording-reproducing type magnetic head 29, particularly the induction type thin-film magnetic head 22, shown in FIG. 8 and FIG. 9 can be obtained by forming the coil and the insulating layer and forming and patterning the upper magnetic core similarly to the embodiment described above.
Now, the four embodiment of this invention will be explained below with reference to FIG. 11.
The width Ws 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 Ws of the surface opposite the MR film may be smaller than the distance Wr 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 Tr of the magnetic field responding part (the width of the protruding part 45a) may be smaller than the distance Wr between the leads 48 and the width Ws 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 Ws 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.
For example, the lower shield layer 42 and the lower magnetic gap layer 43 are formed as by the spattering technique on the substrate 41. Further, the first magnetic film 45, the nonmagnetic film 46, and the second magnetic film 47 jointly destined to form a spin valve film, an antiferromagnetic film, etc. are formed sequentially in the order mentioned as by the vacuum deposition technique. In this case, the deposition of a noble metal film as a protective film on the spin valve film proves to be an effective measure.
The soft magnetic film 55 is desired to be formed of a soft magnetic material possessing higher resistance than the first magnetic film 45. To be specific, the soft magnetic film 55 is desired to possess a specific resistance of not less than 100 μΩm, for this high specific resistance suffices to preclude the otherwise possible partial diversion of electric current into the soft magnetic film 55. The materials desirably used for the soft magnetic film 55 include NiFe alloy, NiFeCo alloy, alloys obtained by combining these magnetic alloys with such additive elements as Ti, V, Cr, Mn, Zn, Nb, Mo, Tc, Hf, Ta, W, and Re and consequently furnished with increased resistance, and alloys obtained by combining Co with the same additive elements and consequently furnished with amorphous or microcrystalline texture, for example. The amorphous magnetic alloys and microcrystalline magnetic alloys obtained as described above generally manifest high resistance.
Incidentally, the fifth and the sixth embodiment represent cases of using a spin valve film as the MR film. It is optional with the manufacturer to use an anisotropic magnetoresistance effect film and a artificial lattice film instead. When the magnetic field responding part to be used is formed of a protruding part, however, since the sense current is curved in the protruding part, it is particularly desirable to use a spin valve film or a artificial lattice film the magnitude of resistance of which does not depend on the angle to be formed between the sense current and the direction of magnetization of film.
As shown in FIGS. 17a, b, c, d, e and f, for example, a resist 62 is formed on a trench-forming insulating layer 61 made as of SiO2 (a in FIG. 17) and the insulating layer 61 is subjected to a chemical dry etching (CDE) treatment using a CF4 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 spattering 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/cm2 on the spatter. 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.
The process of production described above allows the magnetic material layer 64 to be obtained in a perfect state without containing such defects as gross porosity because the magnetic material 63 is embedded in the trench 61a having a two-step tapered cross section. The use of a collimation spattering technique in this case can further improve the state of embedment of the magnetic material 63. Further, owing to the use of the trench 61a having the two-step tapered cross section, the magnetic material layer 64 having a protrusion-containing cross section fit for the upper magnetic core of the induction type thin-film magnetic head can be formed.
FIGS. 18a, b, c, d and e show 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 SiO2 and then the RIE treatment is performed by the use of the CHF3 gas so as to cool the substrate to about 273 K 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 273 K thereby forming a deposit 65 on the lateral walls of the etched cavity (a in FIG. 18). Then, the RIE treatment as with CF4 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).
FIGS. 19a, b, c, d and e depict 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 SiO2 and then the RIE treatment as with CF4 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 CHF3 gas is carried out to cool the substrate to about 0� C. and, at the same time, etch the insulating 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).
Now, the process for the production of the MR head which is constructed as described above will be described below with reference to FIGS. 24a, b and c and FIGS. 25a and b.
Then, an amorphous soft magnetic alloy 74a destined to form the lower shield layer 74 is filled in the trench 73a mentioned above (b in FIG. 24) and the unnecessary part of the filled soft magnetic alloy is removed by the polishing technique to give rise to the lower shield layer 74 (c in FIG. 24). In this case, the magnetic characteristic of the embedding type lower shield layer 74 in the edge part thereof can be easily controlled when a taper has been imparted to the lateral walls of the trench 73a during the preceding etching step. The embedment of the magnetic material mentioned above is particularly desired to be carried out by the collimation spattering technique.
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 Al2 O3, 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 SiO2 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 O2 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.
The separate recording-reproducing magnetic head which is constructed as described above is enabled to acquire a substantially flattened upper surface, because the upper shield layer 82 concurrently serving as the lower magnetic core of the recording head is formed by filling the soft magnetic material in the trench 81a formed in the insulating layer 81, and then removing the unnecessary part of the filled material. Specifically, the recording magnetic gap 84 endowed with linearity of not more than 0.1 μm can be easily obtained.
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