Gerardo A Bertero

US Patent:

6482505, Nov 19, 2002

Filed:

May 11, 2000

Appl. No.:

09/569345

Inventors:

Gerardo Bertero - Redwood City CA
Javier Wong - San Francisco CA
Tu Chen - Monte Sereno CA

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B 582

US Classification:

428212, 428433, 428612, 428667, 428680, 428694 ST, 428694 SG

Abstract:

A method for improving corrosion resistance while maximizing magnetic performance of a magnetic disk employed in data storage applications. The invention includes providing a substrate and forming a first layer above the substrate, the first layer having a first degree of abrasion resistance. The invention includes forming a second layer such as a Ni-containing layer above the first layer, the Ni-containing layer having a second degree of abrasion resistance lower than the first degree of abrasion resistance. The invention further includes forming grooves in the Ni-containing layer.

US Patent:

6500567, Dec 31, 2002

Filed:

Oct 3, 2000

Appl. No.:

09/677644

Inventors:

Gerardo Bertero - Redwood City CA
Charles Changqing Chen - Milpitas CA
Tu Chen - Monte Sereno CA
Tsutomu Yamashita - San Jose CA
Makoto Imakawa - Sendai, JP
Michinobu Suekane - Hino, JP

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B 566

US Classification:

428667, 428332, 428336, 428694 TS, 428694 TM, 427128, 427129, 427130, 427131, 2041922

Abstract:

In this invention, an ultra thin layer of CoCr alloy nucleation layer is sputtered at an extremely low deposition rate above a predominantly (200) oriented Cr film followed by a CoCrPt based alloy sputtered film at higher rates and moderate temperatures. This structure creates a media which has very high Hc, and excellent PW50, low noise and excellent low TNLD values. By using this technique, the CoCrPt magnetic film achieves excellent in-plane crystallographic orientation, and high Hc is achieved with minimal amount of Pt addition to the magnetic film. The method allows very fine grain structure of cobalt to be formed which contributes to good signal to noise ratio. A fine grain structure combined with chromium segregation between the grains improve the signal to noise ratio even more. A high degree of in-plane c-axis orientation is achieved in the cobalt layer which provides very high hysteresis loop squareness which helps to improve the OW and TNLD. The perfection of the grains is very high so that high anisotropy is obtained in the magnetic layer, resulting in high Hc without the necessity of addition of high level of Pt.

US Patent:

6730420, May 4, 2004

Filed:

Oct 31, 2000

Appl. No.:

09/703607

Inventors:

Gerardo Bertero - Redwood City CA
Tu Chen - Monte Sereno CA
Charles Chen - Milpitas CA
Wei Cao - Milpitas CA

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B 566

US Classification:

428694TS, 428694 TM, 428900, 428216, 428336, 427131, 427132

Abstract:

A magnetic medium having at least two intermediate layers between an underlayer and a magnetic layer. The first intermediate layer is designed to provide a good lattice match to the underlayer, while the second intermediate layer is designed to provide a good lattice match to the magnetic layer. Typically, the underlayer has one structure, such as body centered cube, while the magnetic layer has a second structure such as hexagonal close pack. In preferred embodiments, the transition from the one structure to the other structure occurs in the intermediate layers. For example, the first intermediate layer may be a hexagonal close pack structure. Because of the mismatch between the underlayer and the first layer, there may be crystal defects in this first intermediate layer. However, any remaining stress and mismatch is absorbed through the second layer, so that the second layer presents a substantially defect-free surface on which the magnetic layer may grow. Because the second layer is closely matched to the magnetic layer, the magnetic layer continues to grow in a defect-free fashion.

US Patent:

6893748, May 17, 2005

Filed:

May 20, 2003

Appl. No.:

10/442756

Inventors:

Gerardo Bertero - Redwood City CA, US
David Wachenschwanz - Saratoga CA, US
Sudhir Malhotra - Fremont CA, US
Emur M. Velu - Fremont CA, US

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B005/66
G11B005/70
B05D005/12

US Classification:

428694TM, 428694 TS, 428212, 428336, 428900, 427130, 427131

Abstract:

A perpendicular magnetic recording disk having a soft magnetic film disposed between a substrate and a magnetic recording layer. The soft magnetic film includes a soft magnetic underlayer and one or more layer groups having a spacer layer and a soft magnetic layer disposed above the spacer layer in each layer group. The spacer layers induce anti-ferromagnetic coupling between the surrounding ferromagnetic layers. The spacer layers may be comprised of ruthenium. The soft magnetic layers may have a granular decoupled structured through the use of a segregate.

US Patent:

6899959, May 31, 2005

Filed:

Feb 12, 2002

Appl. No.:

10/075123

Inventors:

Gerardo Bertero - Redwood City CA, US
Sudhir Malhotra - Fremont CA, US
David Wachenschwanz - Saratoga CA, US
Zhengsheng Shan - Fremont CA, US
Donald Stafford - Fremont CA, US

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B005/66

US Classification:

428611, 428637, 428668, 428669, 428678, 428 653, 428212, 428409, 428694 TM, 360131

Abstract:

A magnetic recording medium includes a substrate, an underlayer, a lower magnetic layer formed on the underlayer, an intermediate layer, and an upper magnetic layer formed on the intermediate layer. The intermediate layer is typically Ru, and promotes antiferromagnetic coupling between the upper and lower magnetic layers. The upper and lower magnetic layers are typically Co alloys. The lower magnetic layer has a high saturation magnetization Ms to promote high exchange coupling between the upper and lower magnetic layers. The dynamic coercivity of the lower magnetic layer is lower than the exchange field to ensure rapid switching of the lower magnetic layer.

US Patent:

7070870, Jul 4, 2006

Filed:

Feb 1, 2005

Appl. No.:

11/048153

Inventors:

Gerardo Bertero - Redwood City CA, US
Sudhir Malhotra - Fremont CA, US
David Wachenschwanz - Saratoga CA, US
Zhengsheng Shan - Fremont CA, US
Donald Stafford - Fremont CA, US

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B 5/66

US Classification:

428828, 4288281, 360131

Abstract:

A magnetic recording medium includes a substrate, an underlayer, a lower magnetic layer formed on the underlayer, an intermediate layer, and an upper magnetic layer formed on the intermediate layer. The intermediate layer is typically Ru, and promotes anti ferromagnetic coupling between the upper and lower magnetic layers. The upper and lower magnetic layers are typically Co alloys. The lower magnetic layer has a high saturation magnetization Ms to promote high exchange coupling between the upper and lower magnetic layers. The dynamic coercivity of the lower magnetic layer is lower than the exchange field to ensure rapid switching of the lower magnetic layer.

US Patent:

7147790, Dec 12, 2006

Filed:

Nov 27, 2002

Appl. No.:

10/306315

Inventors:

David E. Wachenschwanz - Saratoga CA, US
Gerardo A. Bertero - Redwood City CA, US
David Treves - Palo Alto CA, US
Andrew Homola - Morgan Hill CA, US
James L. Chao - Fremont CA, US
Christopher H. Bajorek - Los Gatos CA, US

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B 3/00

US Classification:

216 22, 216 67, 216 52, 216 88, 264106, 264320

Abstract:

A method of forming a discrete track recording pattern on a soft magnetic underlayer of a perpendicular magnetic recording disk. In one embodiment, the soft magnetic underlayer is continuous throughout the discrete track recording pattern.

US Patent:

7179549, Feb 20, 2007

Filed:

Jan 21, 2004

Appl. No.:

10/761820

Inventors:

Sudhir S. Malhotra - Fremont CA, US
Gerardo Bertero - Redwood City CA, US
Ching Tsoi - Cupertino CA, US
Donald Stafford - San Jose CA, US

Assignee:

Komag, Inc. - San Jose CA

International Classification:

G11B 5/66
G11B 5/70

US Classification:

4288312, 427131

Abstract:

A magnetic recording medium constructed in accordance with the invention comprises a substrate, first, second and third underlayers formed over the substrate, and a magnetic data recording layer formed over the underlayers. The underlayers typically have a bcc crystal structure, and comprise Cr or Cr alloys. The magnetic data recording layer has a hcp crystal structure and comprises a Co alloy. The second underlayer typically comprises a material such as B, which tends to reduce the crystal size of the second underlayer and the layers deposited thereon, and also to increase crystal spacing.