Writer design eliminating transition curvature for very narrow writer widths

ABSTRACT

A magnetic transducer having a top pole and a bottom pole where the top pole is separated from the bottom pole by a gap layer. The top pole has a lower portion that faces the bottom pole. A middle section of the lower portion is separated from the bottom pole by a first distance and end sections of the lower portion are separated from the bottom pole by a second distance not equal to the first distance. The second distance is greater than 25% of the first distance.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 shows an air-bearing surface (ABS) view of a magnetic thin film head for recording transitions on a moving magnetic medium (not shown) according to a preferred embodiment of the present invention. The head includes a bottom pole , a top pole and a gap . In a preferred embodiment the bottom pole consists of layer and a top layer called a mesa. A non-magnetic regions abuts each end of the magnetic region . The magnetic region preferably has a width substantially equal to the width of the layer or top pole . The top pole preferably has a seed layer on its end that faces the bottom pole . The seed layer is shaped so that a gap GL exists between the top pole and bottom pole . In addition, a smaller gap GL exists at each end portion of the top pole . In a preferred embodiment, GL ranges from about 25% to about 60% of GL. More preferably GL is about 60% of GL . Preferably GL2/GL1<1.0.

In the preferred embodiment shown in FIG. 1, the end portions of the top pole are rectangular in shape. The fabrication of a head according to the present invention will be described in greater detail hereinafter. The gap is preferably filled by a nonmagnetic material such as silicon oxide, silicon nitride, nickel palladium, Al2O3, T1, titanium.

The head shown in FIG. 1 has a width TPWG that can range from about 0.3 microns to about 1.5 microns. In a preferred embodiment TPWG is about 0.5 microns. The gap length GL is about one-third of TPWG. Thus, GL can range from about 0.1 microns to about 0.3 microns and in a preferred embodiment is about 0.15 microns.

The top pole is preferably made of magnetic material preferably Fe based alloys like NiFeCo, NiFe, FeTaN, FeAIN or any other iron nitrate with Hf or Zr additives. The seed layer can be formed of the materials like those used in the top pole by sputtering, or electroplating. The shared pole of the bottom pole is preferably made of Fe based alloy. The magnetic material deposited on the shared pole is preferably formed of high moment Fe-based alloy. The nonmagnetic regions are preferably formed of alumina, SiO2, SiN, Ti. Alternatively, the magnetic and nonmagnetic regions , can be eliminated so that the bottom pole is flat and does not have mesa.

FIG. 2 shows an ABS view of a head according to a second preferred embodiment of the present invention. The head according to this preferred embodiment is identical to that shown in FIG. 1 except for end portions of the top pole . In this preferred embodiment the end portions are shaped as wedges. Thus, GL ranges from about 60% of GL at its outer most point to GL at its inner most point.

FIG. 3 shows an ABS view of a head according to a third preferred embodiment of the present invention. The head according to this preferred embodiment is identical to that shown in FIG. 1 except for end portions . In this preferred embodiment, the surface of the end portions that face the bottom pole are angled so that its outermost point has a gap length GLa and at its innermost point it has a gap length GLb. In a more preferred embodiment, GLa

The method of fabricating a head according to a preferred embodiment of this invention will now be described with reference to FIGS. 6-10. A shared pole material is first deposited on a reader gap. Deposition can be done by electroplating or any vacuum technique such as sputtering. The deposited material can be as thick as 2 um to 5 um of the gap material which can be composed of alternating layers of magnetic and non-magnetic material, is then deposited on the pole material via electroplating (i.e., NiPd) or sputtering Al2O3, SiN, SiO2. The gap material is patterned with a photoresist layer and has a width less than the design width of the top pole. An ion mill is used to remove the gap material on either side of photoresist. The variety of writer gap slope angles can be reached through a careful selection of the mill angle and mill energy. A lift off operation removes the photoresist layer used in the definition of the writer gap shape. A seed layer, and and top pole , defined in FIGS. 1 to , are deposited through a thick photoresist mask carefully aligned with writer gap feature (not shown in a drawing). The seed layer should have a magnetic moment Bsat higher than 1 Tesla, preferably higher than the magnetic material used in the top pole. The seed layer thickness can be from 500 Angstroms to 300 Angstroms. The seed layer defines the structure of the first top pole. In the next step, a wet etch chemical removes the thick photoresist and is followed by an ion mill process to remove the seed layer.

After that another resist (not shown) is deposited to protect all the surfaces except the pole tip area. This step is necessary to implement a second mill process which removes the bottom pole material and defines the mesa under the writer gap. In the mill process, the thickness of top pole is reduced, therefore the plating has to be thick enough to get a final top pole thickness required by design.

After the mesa is defined, a nonmagnetic material is deposited adjacent to bottom pole and the top pole .

This path can be used for writers with a single top pole or writers with two piece top poles. In the last case the top pole layer is chemically mechanically polished to create a flat top surface as shown in FIG. .

Current writers implementing high moment materials (Bsat>1.0 Tesla) suffer from creating transitions that are curved. The situation worsens with the smaller writer gaps, narrower TPWG and high write currents, as the curved part of transition becomes a significant part of the written track. The edge effects become dominant as the width of the top pole decreases and the curved part of the transition becomes a significant portion of the written track. The curved transistion increases the transition parameter. The deterioration of the transition parameter adversely impacts the width of the pulse at half amplitude, termed also as PW50. The situation worsens even further at the higher bit per inch densities. Both transition parameter and PW50 are described on p. 213 and p. 133 in the “Theory of magnetic recording” by H. N. Bertram ed. by Cambridge University Press 1994.

Buildup of the charges at the edges of the writer's top pole causes curving of the transitions. The present invention shifts the charge build up in a controlled fashion, down from the trailing edge at the edges of the gap and effectively straightens previously curved part of the written transition. High moment seed material assures higher field gradients compared to a structure with a flat top pole. The method described above assures good control of the track curvature even for an extremely narrow writer widths, i.e., TPWG=0.5-1.0 μm.

The best results are observed with the seed layer material exceeding the saturation moment of the top pole material. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an air-bearing surface (ABS) view of a magnetic thin film head according to a preferred embodiment of the present invention.

FIG. 2 shows an ABS view of a head according to a second preferred embodiment of the present invention.

FIG. 3 shows an ABS view of a head according to a third preferred embodiment of the present invention.

FIG. 4 shows an ABS view of a head according to a fourth preferred embodiment of the present invention.

FIG. 5 shows an ABS view of a head according to a fifth preferred embodiment of the present invention.

FIGS. 6-10 illustrate a method for fabricating a head according to a preferred embodiment of the present invention.

This application claims the benefit of provisional application Ser. No. 60/109,107 filed Nov. 18, 1998.

CLAIMS

1. A magnetic transducer writing device including a written transition having a curved portion, the device comprising: a bottom magnetic pole; a nonmagnetic gap layer deposited over said bottom magnetic pole; a top magnetic pole deposited over the nonmagnetic gap layer and including a high moment material having a magnetic moment saturation greater than 1 Tesla (Bsat>1 Tesla), the top magnetic pole having an upper portion and a lower portion wherein the lower portion of the top magnetic pole faces a surface of the bottom magnetic pole and wherein the lower portion has a middle section that is separated from the bottom pole by the nonmagnetic gap layer by a first distance and the lower portion has end portions located at each end of the middle portion that are separated from the bottom pole by the nonmagnetic gap layer by a second distance wherein the second distance is greater than 25% and less than 100% of the first distance, and the top magnetic pole reduces the curved portion of the written transition.

2. The device of claim 1 wherein the second distance is at least 40% of the first distance.

3. The device of claim 1 wherein the second distance is at least 50% of the first distance.

4. The device of claim 1 wherein the second distance is at least 60% of the first distance.

5. The device of claim 1 wherein the second distance ranges from about greater than 25% to about 60% of the first distance.

6. The device of claim 1 wherein the device has a width (TPWG) measured between a left and a right side of the top magnetic pole wherein the width ranges from about 0.3 microns to about 1.5 microns.

7. The device of claim 6 wherein the width ranges from about 0.3 microns to about 0.5 microns.

8. The device of claim 6 wherein the first distance is about 30% of the width of the device.

9. The device of claim 6 wherein the bottom magnetic pole comprises a shared pole, a magnetic layer deposited on the shared pole wherein the magnetic layer has a width equal to the width of the device, and a nonmagnetic region deposited on the shared pole at each end of the magnetic region.

10. The device of claim 1 wherein the first distance ranges from about 0.1 microns to about 0.3 microns.

11. The device of claim 1 wherein the first distance ranges from about 0.1 microns to about 0.15 microns.

12. The device of claim 1 wherein the end portions each have a surface that is substantially parallel with the surface of the bottom magnetic pole.

13. The device of claim 1 wherein the end portions are square in shape.

14. The device of claim 1 wherein the end portions are wedged in shape.

15. The device of claim 1 wherein the end portions have a surface that faces the surface of the bottom magnetic pole wherein the surface of the end portions are angled so that at one end of the end portion the distance between the end portion and the bottom magnetic pole is greater than at an opposite end of the end portion.

16. The device of claim 15 wherein the distance is greatest between the end portions and the bottom magnetic pole at the end portion closest to the middle portion of the top magnetic pole.

17. The device of claim 1 wherein each end portion of the top magnetic pole is defined by a segment connecting two points.

18. The device of claim 17 wherein the segment is linear.

19. The device of claim 17 wherein the segment is curvilinear.

20. The device of claim 19 wherein the segment is convex with respect to the bottom magnetic pole.

21. The device of claim 19 wherein the segment is concave with respect to the bottom magnetic pole.

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