Perpendicular write head with tapered main pole
Prior art designs of single pole writers have been limited by premature saturation at the tip. This limits the head field that can be achieved without simultaneously widening the write profile. This problem has bee solved by means of a vertical main pole whose thickness has its conventional value a short distance from the tip but that tapers down to a significantly reduced value as it approaches the tip. A process for manufacturing this tapered tip design is also presented.
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The invention relates to the general field of magnetic disk systems with particular reference to perpendicular write poles and controlling flux therefrom.
BACKGROUND OF THE INVENTIONOne of the key advantages of single-pole (SP) head/media, with a magnetically soft underlayer (SUL) and perpendicular recording system, is the capability of providing a larger write field (than that of a ring head) to enable writing into the relatively thick media with high anisotropy constant. The latter quality leads one to assume better thermal stability associated with perpendicular recording. However, this advantage is diminished as the dimension of the pole tip is reduced to increase the areal recording density [1]. So, the tradeoff between head writing field and thermal stability may still limit the achievable areal density for perpendicular recording.
An enlarged view of the write and return poles is shown in
To increase the write field, large W and t and small NH are preferred (as defined in
A large pole width t will result in head skew problems [3]. Thus better methods for compensating field loss at ultra-high recording densities are essential. The present invention discloses a novel structure for a perpendicular write head that overcomes these problems.
REFERENCES
- (1) Z. Bai, and J.-G. Zhu, “Micromagnetics of Perpendicular Write Heads with Small Pole-Tip Dimensions”, J. Appl. Phys, vol. 91, 6833 (2001).
- (2) J. Schare, L. Guan, J. G. Zhu, and M. Kryder, “Design Considerations for Single-Pole Type Write Heads”, IEEE Tran. Magn., May, 2003
- (3) R. Wood, T. Sonobe, Z. Jin, and B. Wilson, “Perpendicular recording: the promise and the problems”, J. Magn. Magn. Mater., vol 235, 1 (2001)
A routine search of the prior art was performed with the following references of interest being found:
-
- U.S. Pat. No. 5,600,519 (Heim et al) discloses a tapered main pole as does U.S. Pat. No. 5,173,821 (Maloney).
It has been an object of at least one embodiment of the present invention to provide a single pole vertical write head having both a large head field as well as good spatial resolution.
Another object of at least one embodiment of the present invention has been to provide a process for manufacturing said vertical writer.
A further object of at least one embodiment of the present invention has been that said process introduce little or no changes to current processes for manufacturing vertical writers.
These objects have been achieved by means of a vertical main pole whose thickness has its conventional value a short distance from the tip but that tapers down to a significantly reduced value as it approaches the tip. Typically, the distance over which this tapering takes place is about 0.1 to 4 microns. In order to manufacture this structure, a trench is etched, using ion milling, partly into the yoke region and partly into the insulated coil well. Said trench has sides whose slope is carefully controlled through adjustment of the angle of incidence of the ion beam, this slope determining the afore-mentioned taper. After the trench has been just filled with a high moment layer, a second high moment layer is deposited to complete formation of the pole tip. After an appropriate lapping step to define the ABS, the process is complete.
BRIEF DESCRIPTION OF THE DRAWINGS
We will disclose the present invention through a description of a process for its manufacture. This description will also serve to make clear the structure of the present invention.
Referring now to
Now follows a key novel feature, namely the formation of trench 51, as shown in
Trench 52 is then overfilled with layer 61 of a material capable of a magnetic moment of at least 1.8 T and is then planarized until insulation layer 17 is just exposed, as illustrated in
Next, as seen in
The concept of a tapered main pole is not limited to only single pole perpendicular writers, but is also applicable to a shielded pole type perpendicular write head, a cross-section of which is shown in
In addition to the previously described tapered main pole structure at a leading edge, a tapered main pole at a trailing edge, combined with trailing shield 135, is disclosed here, as shown in
The major process steps to make this trailing-edge-tapered main pole with trailing shield are illustrated in
Claims
1. A method to increase a head field from a single vertical pole, having an air bearing surface, comprising:
- tapering said pole whereby, over a distance of between about 0.1 and 4 microns, its thickness is reduced from between about 0.2 and 2 microns to a lesser thickness of between about 0.1 and 0.4 microns; and
- whereby said lesser thickness extends from said air bearing surface for a distance of no more than about 0.2 and 0.4 microns.
2. The method of claim 1 wherein said increased head field is between about 0.1 and 0.3 T.
3. The method of claim 1 wherein said tapered pole is selected from the group consisting of Ni, Fe, Co, and their alloys.
4. The method of claim 1 wherein, at its tip, said tapered pole has a moment of at least 1.8 T.
5. A process to manufacture a magnetic write head, having a tapered single vertical pole, comprising:
- on a substrate, depositing a return pole layer;
- forming, on said return pole layer, a magnetic yoke that includes a well within which is a coil embedded in a layer of insulation that shares a common first upper surface with said yoke;
- forming a trench, having sloping sides and a depth, that extends downwards from said first upper surface;
- overfilling said trench with a first layer of a material that has a moment of at least 1.8 T and then planarizing until said first upper surface is just exposed, thereby forming a second upper surface;
- then depositing a layer of a second material having a moment of at least 2 T, thereby forming said magnetic write head, including said tapered single vertical pole; and
- forming an air bearing surface by planarizing in a plane normal to said upper surfaces.
6. The process described in claim 5 wherein said return pole is deposited to a thickness between about 0.5 and 5 microns.
7. The process described in claim 5 wherein said return pole is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
8. The process described in claim 5 wherein said coil well is formed to a depth of between about 0.5 and 4 microns.
9. The process described in claim 5 wherein said insulating layer is aluminum oxide.
10. The process described in claim 5 wherein ion beam milling is used to form said trench.
11. The process described in claim 5 wherein the depth of said trench is between about 0.2 and 3 microns.
12. The process described in claim 11 wherein said trench depth is controlled through adjustment of said ion beam's dose and duration.
13. The process described in claim 5 wherein the sides of the trench slope at an angle between about 15 and 65 degrees from vertical.
14. The process described in claim 13 wherein said slope angle is controlled through adjustment of said ion beam's angle of incidence.
15. The process described in claim 5 wherein said yoke is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
16. The process described in claim 5 wherein said first layer of a material that has a moment of at least 1.8 T is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
17. The process described in claim 5 wherein said second layer of a material that has a moment of at least 2 T is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
18. The process described in claim 5 wherein said return pole layer is located behind a trailing edge of said vertical pole.
19. The process described in claim 5 wherein said return pole layer is located in front of a leading edge of said vertical pole.
20. A magnetic write head, having a tapered single vertical pole, comprising:
- a return pole layer on a substrate;
- on said return pole layer, a magnetic yoke that includes a well within which is a coil embedded in a layer of insulation that shares a common first upper surface with said yoke;
- a trench, having sloping sides and a depth, that extends downwards from said first upper surface;
- said trench being exactly filled with a first layer of a material capable of a magnetic moment of at least 1.8 T and a second upper surface;
- on said second upper surface, a layer of a second material having a capable of a magnetic moment of at least 2 T; and
- an air bearing surface in a plane normal to said upper surfaces.
21. The magnetic write head described in claim 20 wherein said return pole is deposited to a thickness between about 0.5 and 5 microns.
22. The magnetic write head described in claim 20 wherein said return pole is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
23. The magnetic write head described in claim 20 wherein said coil well has a depth of between about 0.5 and 4 microns.
24. The magnetic write head described in claim 20 wherein said insulating layer is aluminum oxide.
25. The magnetic write head described in claim 20 wherein the depth of said trench is between about 0.2 and 3 microns.
26. The magnetic write head described in claim 20 wherein the sides of the trench slope at an angle between about 15 and 65 degrees from vertical.
27. The magnetic write head described in claim 20 wherein said yoke is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
28. The magnetic write head described in claim 20 wherein said first layer of a material that is capable of a magnetic moment of at least 1.8 T is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
29. The magnetic write head described in claim 20 wherein said second layer of a material that is capable of a magnetic moment of at least 2 T is a material selected from the group consisting of Ni, Fe, Co, and their alloys.
30. A magnetic write head, having an ABS, a main pole, and a trailing edge, comprising:
- said trailing edge being tapered at an angle of 15 to 60 degrees from vertical;
- wherein said taper of the trailing edge begins at a distance of less than about 0.3 microns from said ABS;
- wherein said taper of the trailing edge is present over a distance of up to about 2 microns from said ABS;
- behind said main pole, a trailing shield having a thickness between about 0.05 and 0.5 microns;
- wherein there is a constant horizontal separation between said main pole and said trailing shield; and
- wherein said shield is tapered at an angle equal to said main pole taper angle.
31. The magnetic write head described in claim 30 wherein said constant separation between said main pole and said trailing shield is between about 0.02 and 0.2 microns.
32. The magnetic write head described in claim 30 further comprising one or more side shields around said main pole.
33. The magnetic write head described in claim 30 further comprising:
- a return pole;
- on said return pole, a magnetic yoke that includes a well within which is a coil embedded in a layer of insulation having a first upper surface;
- a trench, having a floor and a sloping sidewall, formed from said first upper surface;
- a first layer of a material, capable of a magnetic moment of at least 1.8 T, that more than fills said trench and that has a second upper surface; and
- on said second upper surface, a layer of a second material capable of a magnetic moment of at least 2 T.
Type: Application
Filed: Apr 6, 2004
Publication Date: Oct 6, 2005
Applicant:
Inventors: Lijie Guan (Milpitas, CA), Hung Hu (Los Altos Hills, CA), Yaw Tang (Saratoga, CA)
Application Number: 10/818,577