US5820769A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for making magnetic storage having discrete elements with quantized magnetic moments
Assignee: University of Minnesota System
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Filing: 1995-05-24
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Granted: 1998-10-13
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Expires: 2015-05-24
Abstract
Abstract A magnetic storage includes a non-magnetic substrate. A plurality of discrete single magnetic domain elements formed of a magnetic material separated by nonmagnetic materials are carried on the non-magnetic substrate. Each single magnetic domain element has the same size, shape and has, without an external magnetic field, two quantized magnetization values. The two magnetization values are of substantially equal magnitude but of differing vector directions. The plurality of single domain elements are adapted for magnetic storage of information based upon direction of the magnetization vector. Each single magnetic domain element is used to store a bit of binary information. Writing each bit becomes to flip the quantified magnetic moment directions. Each bit can be tracked individually. The switching field of each bit can be controlled by controlling the size and shape anisotropy of each bit. Methods of fabricating the magnetic storage medium include obtaining the non-magnetic substrate and forming the plurality of single magnetic domain elements on the substrate.
Inventors
- 👤 Stephen Y. Chou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:57
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; B; B82; B82Y; B82Y10/00; G11B5/74; G11B5/743; G11B5/746; G11B5/84; G11B5/855; G11B2005/0002; G11B2005/0026; G11B2005/0029; G11B5/80; G11B5/82
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
116 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; obtaining a magnetic material; and forming the magnetic material on the substrate in a plurality of discrete single-magnetic-domain elements each having shape anisotropy, spacing and dimension wherein each one of the single-magnetic-domain elements has a single magnetic domain in which substantially all magnetic moments within the element magnetize into a single direction without an external magnetic field, the magnetic domain having one or another of at most two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and wherein the elements are separated from one another to a spacing large enough that interaction between neighboring single-magnetic-domain elements is substantially eliminated.
Claim 2
Independent Claim
116 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; obtaining a magnetic material; and forming the magnetic material on the substrate in a plurality of discrete single-magnetic-domain elements each having shape anisotropy, spacing and dimension wherein each one of the single-magnetic-domain elements has a single magnetic domain in which substantially all magnetic moments within the element magnetize into a single direction without an external magnetic field, the magnetic domain having one or another of at most two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and wherein the elements are separated from one another to a spacing large enough that interaction between neighboring single-magnetic-domain elements is substantially eliminated.
Claim 3
Dependent Claim
58 words
The method of claim 1 wherein the step of forming comprises: forming a mask over a surface of the substrate; etching the substrate through the mask and forming a plurality of cavities in the substrate; removing the mask; depositing the magnetic material in the cavities and the rest of the substrate; and polishing the surface of the substrate.
Claim 4
Dependent Claim
35 words
The method of claim 1 wherein the step of forming comprises: depositing magnetic layers on the substrate; forming a mask over the magnetic layers; etching the magnetic layer through the mask; and removing the mask.
Claim 5
Dependent Claim
35 words
The method of claim 1 wherein the step of forming comprises: depositing a non-magnetic material on the substrate; forming a plurality of cavities in the non-magnetic material; and depositing the magnetic material in the cavities.
Claim 6
Dependent Claim
51 words
The method of claim 4 wherein forming the plurality of cavities in the non-magnetic material comprises: applying a photoresist mask over the non-magnetic material; patterning the plurality of cavities in the mask; developing the mask; etching the cavities in the non-magnetic material through openings of the mask; and removing the mask.
Claim 7
Dependent Claim
42 words
The method of claim 4 wherein forming the plurality of cavities comprises: obtaining a mold having a plurality of protrusions; and applying the mold to the non-magnetic material whereby the plurality of protrusions impress the plurality of cavities in the non-magnetic material.
Claim 8
Dependent Claim
51 words
The method of claim 4 wherein forming the plurality of cavities in the non-magnetic material comprises: applying a mask over the non-magnetic material; forming a plurality of cavities in the mask with a mold; forming the cavities in the non-magnetic material through the cavities in the mask; and removing the mask.
Claim 9
Dependent Claim
29 words
The method of claim 1 wherein the step of forming includes a magnetic material deposition step selected from the group consisting of chemical vapor deposition, sputtering, plating and evaporation.
Claim 10
Dependent Claim
19 words
The method of claim 1 wherein, in the step of forming elements, the elements are formed at predetermined locations.
Claim 11
Dependent Claim
60 words
The method of claim 1 wherein the step of forming elements includes the substeps of: applying a mask layer over the non-magnetic substrate; obtaining a mold having a plurality of protrusions at predetermined locations; forming a plurality of cavities in the mask layer with the mold; and forming the elements at locations determined by the cavities in the mask layer.
Claim 12
Independent Claim
110 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; depositing a plating base on the substrate; forming a mask layer on the plating base, the mask layer having discrete separated mask openings to the plating layer; and plating pillars of a magnetic material in the mask openings to the plating layer, the pillars forming a plurality of discrete single-magnetic-domain elements having a preferred-shape anisotropy, spacing and dimension wherein the single-magnetic-domain elements have two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and which are separated to a spacing large enough that interaction between neighboring single-magnetic-domain elements is either greatly reduced or eliminated.
Claim 13
Independent Claim
110 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; depositing a plating base on the substrate; forming a mask layer on the plating base, the mask layer having discrete separated mask openings to the plating layer; and plating pillars of a magnetic material in the mask openings to the plating layer, the pillars forming a plurality of discrete single-magnetic-domain elements having a preferred-shape anisotropy, spacing and dimension wherein the single-magnetic-domain elements have two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and which are separated to a spacing large enough that interaction between neighboring single-magnetic-domain elements is either greatly reduced or eliminated.
Claim 14
Dependent Claim
16 words
The method of claim 11 wherein a surface of the plating base comprises gold or titanium.
Claim 15
Dependent Claim
11 words
The method of claim 11 wherein the magnetic material comprises nickel.
Claim 16
Dependent Claim
15 words
The method of claim 13 wherein the pillars have a diameter of approximately 35-40 nanometers.
Claim 17
Dependent Claim
21 words
The method of claim 13 wherein the pillars have a spacing period of at least approximately three times a pillar diameter.
Claim 18
Dependent Claim
19 words
The method of claim 13 wherein the pillars have a pillar height of approximately 100 and approximately 800 nanometers.
Claim 19
Dependent Claim
19 words
The method of claim 13 wherein the step of plating includes plating at a rate of about 45 nanometers/minute.
Claim 20
Dependent Claim
34 words
The method of claim 13 wherein the step of plating includes plating to a height above a final pillar height, and further comprising the step of: polishing the pillars to the final pillar height.
Claim 21
Dependent Claim
70 words
The method of claim 13 wherein the step of forming a mask layer on the plating base comprises the steps of: forming a layer of SiO 2 above the plating layer; forming an etch-mask layer above the SiO 2 layer, the etch mask layer having holes through to the SiO 2 layer; and subjecting the SiO 2 layer adjacent to the holes to reactive ion etching to form cavities therethrough.
Claim 22
Dependent Claim
31 words
The method of claim 11 wherein, in the step of forming a mask layer, the mask layer having discrete separated mask openings to the plating layer, the openings having predetermined locations.
Claim 23
Dependent Claim
58 words
The method of claim 11 wherein the step of forming a mask layer includes the substeps of: applying a mask layer over the non-magnetic material; obtaining a mold having a plurality of protrusions; forming a plurality of recesses in the mask with the mold; and forming the cavities in the non-magnetic material through the recesses in the mask.
Claim 24
Independent Claim
213 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; depositing a plating base on the substrate; forming a mask layer on the plating base, the mask layer having discrete separated mask openings to the plating layer, the openings having predetermined locations; and plating pillars of a magnetic material in the mask openings to the plating layer, the pillars forming a plurality of discrete single-magnetic-domain elements having a preferred-shape anisotropy, spacing and dimension wherein the single-magnetic-domain elements have two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and which are separated to a spacing large enough that interaction between neighboring single-magnetic-domain elements is either greatly reduced or eliminated; wherein the magnetic material comprises nickel; and wherein the step of forming a mask layer on the plating base comprises the steps of: forming a layer of SiO 2 above the plating layer; forming a layer of chrome above the SiO 2 layer; forming an etch-mask layer above the chrome layer, the etch mask layer having holes through to the chrome layer; subjecting the chrome layer to a chrome etch to form vias therethrough; extending the vias through the SiO 2 layer using a reactive ion etching technique or ion milling; and removing the etch-mask and chrome layers.
Claim 25
Independent Claim
213 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; depositing a plating base on the substrate; forming a mask layer on the plating base, the mask layer having discrete separated mask openings to the plating layer, the openings having predetermined locations; and plating pillars of a magnetic material in the mask openings to the plating layer, the pillars forming a plurality of discrete single-magnetic-domain elements having a preferred-shape anisotropy, spacing and dimension wherein the single-magnetic-domain elements have two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and which are separated to a spacing large enough that interaction between neighboring single-magnetic-domain elements is either greatly reduced or eliminated; wherein the magnetic material comprises nickel; and wherein the step of forming a mask layer on the plating base comprises the steps of: forming a layer of SiO 2 above the plating layer; forming a layer of chrome above the SiO 2 layer; forming an etch-mask layer above the chrome layer, the etch mask layer having holes through to the chrome layer; subjecting the chrome layer to a chrome etch to form vias therethrough; extending the vias through the SiO 2 layer using a reactive ion etching technique or ion milling; and removing the etch-mask and chrome layers.
Claim 26
Independent Claim
105 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; depositing a polymer layer on the substrate; imprinting the polymer layer with a pillar mold to form a plurality of discrete separated pillar cavities in the polymer layer; and depositing a magnetic material in the pillar openings to form pillars, the pillars being discrete single-magnetic-domain elements having an anisotropic shape, spacing and dimension wherein the single-magnetic-domain elements have two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and which are separated to a spacing large enough that interaction between neighboring single-magnetic-domain elements is either greatly reduced or eliminated.
Claim 27
Independent Claim
105 words
A method of fabricating a magnetic storage medium, comprising: obtaining a non-magnetic substrate; depositing a polymer layer on the substrate; imprinting the polymer layer with a pillar mold to form a plurality of discrete separated pillar cavities in the polymer layer; and depositing a magnetic material in the pillar openings to form pillars, the pillars being discrete single-magnetic-domain elements having an anisotropic shape, spacing and dimension wherein the single-magnetic-domain elements have two quantized magnetization values of differing vector directions and substantially equal vector magnitude, and which are separated to a spacing large enough that interaction between neighboring single-magnetic-domain elements is either greatly reduced or eliminated.
Claim 28
Dependent Claim
27 words
The method of claim 23 further comprising the step of: polishing to remove the magnetic material from a surface of the polymer layer but leave the pillars.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-10-12 | 2002-04-13 | 2002-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-10-12 | 2006-04-13 | 2006-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-10-12 | 2010-04-13 | 2010-10-13 | $7700.00 | Window Closed / Lapsed |