Patents by Inventor Yun-Fei Li
Yun-Fei Li has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 7035060Abstract: A problem associated with current bottom spin valve designs is that it is difficult to avoid magnetic charge accumulation at the edge of the sensor area, making a coherent spin rotation during sensing difficult to achieve. This problem has been eliminated by introducing an exchange coupling layer between the free layer and the ferromagnetic layer that is used to achieve longitudinal bias for stabilization and by extending the free layer well beyond the sensor area. After all layers have been deposited, the read gap is formed by etching down as far as this layer. Since it is not critical exactly how much of the biasing layers (antiferromagnetic as well as ferromagnetic) are removed, the etching requirements are greatly relaxed. Whatever material remains in the gap is then oxidized thereby providing a capping layer as well as a good interface for specular reflection in the sensor region.Type: GrantFiled: March 6, 2002Date of Patent: April 25, 2006Assignee: Headway Technologies, Inc.Inventors: Yun-Fei Li, Hui-Chuan Wang, Chyu-Jiuh Torng, Cherng-Chyi Han
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Patent number: 7022383Abstract: Although it is known that exchange bias can be utilized in abutted junctions for longitudinal stabilization, a relatively large moment is needed to pin down the sensor edges effectively. Due to the inverse dependence of the exchange bias on the magnetic layer thickness, a large exchange bias has been difficult to achieve by the prior art. This problem has been solved by introducing a structure in which the magnetic moment of the bias layer has been approximately doubled by pinning it from both above and below through exchange with antiferromagnetic layers. Additionally, since the antiferromagnetic layer is in direct abutted contact with the free layer, it acts directly to help stabilize the sensor edge, which is an advantage over the traditional magnetostatic pinning that had been used.Type: GrantFiled: October 22, 2002Date of Patent: April 4, 2006Assignee: Headway Technologies, Inc.Inventors: Yun-Fei Li, Hui-Chuan Wang, Chyu-Jiuh Torng, Cherng-Chyi Han, Mao-Min Chen
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Publication number: 20060061916Abstract: A problem associated with current bottom spin valve designs is that it is difficult to avoid magnetic charge accumulation at the edge of the sensor area, making a coherent spin rotation during sensing difficult to achieve. This problem has been eliminated by introducing an exchange coupling layer between the free layer and the ferromagnetic layer that is used to achieve longitudinal bias for stabilization and by extending the free layer well beyond the sensor area. After all layers have been deposited, the read gap is formed by etching down as far as this layer. Since it is not critical exactly how much of the biasing layers (antiferromagnetic as well as ferromagnetic) are removed, the etching requirements are greatly relaxed. Whatever material remains in the gap is then oxidized thereby providing a capping layer as well as a good interface for specular reflection in the sensor region.Type: ApplicationFiled: November 7, 2005Publication date: March 23, 2006Inventors: Yun-Fei Li, Hui-Chuan Wang, Chyu-Jiuh Torng, C. C. Han
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Publication number: 20050275975Abstract: A hard bias structure for biasing a free layer in a MR element within a read head is comprised of a composite hard bias layer having a Co78.6Cr5.2Pt16.2/Co65Cr15Pt20 configuration. The upper Co65Cr15Pt20 layer has a larger Hc value and a thickness about 2 to 10 times greater than that of the Co78.6Cr5.2Pt16.2 layer. The hard bias structure may also include a BCC underlayer such as FeCoMo which enhances the magnetic moment of the hard bias structure. Optionally, the thickness of the Co78.6Cr5.2Pt16.2 layer is zero and the Co65Cr15Pt20 layer is formed on the BCC underlayer. The present invention also encompasses a laminated hard bias structure. The Mrt value for the hard bias structure may be optimized by adjusting the thicknesses of the BCC underlayer and CoCrPt layers. As a result, a larger process window is realized and lower asymmetry output during a read operation is achieved.Type: ApplicationFiled: June 15, 2004Publication date: December 15, 2005Inventors: Kunliang Zhang, Yun-Fei Li, Chyu-Jiuh Torng, Chen-Jung Chien
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Publication number: 20050264957Abstract: A hard bias layer that forms an abutting junction with a free layer in a GMR element and is comprised of FePtCu or FePtCuX where X is B, C, O, Si, or N is disclosed. The FePtCu layer has a composition of about 45 atomic % Fe, 45 atomic % Pt, and 10 atomic % Cu and does not require a seed layer to achieve an ordered structure. The FePtCu layer is annealed at a temperature of about 280° C. and has an Hc value more than double that of a conventional CoCrPt hard bias layer with a similar thickness. Since the FePtCu hard bias layer adjoins a free layer, it has a higher sensor edge pinning efficiency than a configuration with a CoCrPt layer on a seed layer. The novel hard bias layer is compatible with either a top or bottom spin valve structure in a GMR sensor.Type: ApplicationFiled: June 1, 2004Publication date: December 1, 2005Inventors: Yun-Fei Li, Kunliang Zhang, Chyu-Jiuh Torng
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Publication number: 20050252576Abstract: In a conventional spin valve the shunt resistance of the pinning layer reduces the overall efficiency of the device. This problem has been overcome by using IrMn for the pinning layer at a thickness of about 20 Angstroms or less. For the IrMn to be fully effective it must be subjected to a two-step anneal, first in the presence of a high field (about 10 kOe) for several hours and then in a low field (about 500 Oe) while it cools. The result, in addition to improved pinning, is the ability to do testing at the full film and full wafer levels.Type: ApplicationFiled: May 14, 2004Publication date: November 17, 2005Inventors: Yun-Fei Li, Hui-Chuan Wang, Tong Zhao, Chyu-Jiuh Torng
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Publication number: 20050141149Abstract: Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.Type: ApplicationFiled: January 14, 2005Publication date: June 30, 2005Inventors: Cheng Horng, Min Li, Ru-Ying Tong, Yun-Fei Li, You Zheng, Simon Liao, Kochan Ju, Cherng Han
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Publication number: 20050128649Abstract: In magnetic read heads based on bottom spin valves the preferred structure is for the longitudinal bias layer to be in direct contact with the free layer. Such a structure is very difficult to manufacture. The present invention overcomes this problem by introducing an extra layer between the bias electrodes and the free layer. This layer protects the free layer during processing but is thin enough to not interrupt exchange between the bias electrodes and the free layer. In one embodiment this is a layer of copper about 5 ? thick and parallel exchange is operative. In other embodiments ruthenium is used to provide antiparallel exchange between the bias electrode and the free layer. A process for manufacturing the structure is also described.Type: ApplicationFiled: January 14, 2005Publication date: June 16, 2005Inventors: Moris Dovek, Po-Kang Wang, Chen-Jung Chien, Chyu-Jiuh Torng, Yun-Fei Li
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Publication number: 20050122637Abstract: Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.Type: ApplicationFiled: January 14, 2005Publication date: June 9, 2005Inventors: Cheng Horng, Min Li, Ru-Ying Tong, Yun-Fei Li, YouFeng Zheng, Simon Liao, Kochan Ju, Cherng Han
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Publication number: 20050122638Abstract: Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.Type: ApplicationFiled: January 14, 2005Publication date: June 9, 2005Inventors: Cheng Horng, Min Li, Ru-Ying Tong, Yun-Fei Li, You Zheng, Simon Liao, Kochan Ju, Cherng Han
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Patent number: 6870711Abstract: A pinned/pinning layer configuration of the form: AP1/coupling bilayer/AP2/AFM, suitable for use in a CIP or CPP GMR sensor, a TMR sensor or an MRAM element, is found to have improved magnetic stability, yield good values of dR/R and have high values of saturation magnetization that can be adjusted to meet the requirements of magnetic field annealing. The coupling bilayer is a layer of Ru/Rh or their alloys, which provides a wide range of coupling strengths by varying either the thickness of the Ru layer or the Rh layer.Type: GrantFiled: June 8, 2004Date of Patent: March 22, 2005Assignee: Headway Technologies, Inc.Inventors: Tong Zhao, Hui-Chuan Wang, Yun-Fei Li, Chyu-Jiuh Torng
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Patent number: 6857180Abstract: Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.Type: GrantFiled: March 22, 2002Date of Patent: February 22, 2005Assignee: Headway Technologies, Inc.Inventors: Cheng T. Horng, Min Li, Ru-Ying Tong, Yun-Fei Li, You Feng Zheng, Simon Liao, Kochan Ju, Cherng Chyi Han
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Patent number: 6842969Abstract: In magnetic read heads based on bottom spin valves the preferred structure is for the longitudinal bias layer to be in direct contact with the free layer. Such a structure is very difficult to manufacture. The present invention overcomes this problem by using a liftoff technique to form, on the free layer, a buffer layer having a trapezoidal cross-section, sloping sidewalls, and a central area of uniform thickness, whose width defines the read track. A suitable bias layer and leads are then deposited on this buffer layer.Type: GrantFiled: April 5, 2002Date of Patent: January 18, 2005Assignee: Headway Technologies, Inc.Inventors: Moris Dovek, Po-Kang Wang, Chen-Jung Chien, Chyu-Jiuh Torng, Yun-Fei Li
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Patent number: 6844999Abstract: Prior art gains in GMR ratio resulting from use of NiFeCr as a seed layer were offset by the resulting high values obtained for Hc and Hk. This problem has been overcome by combining a seed layer of NiCr or NiFeCr with a free layer of boron doped CoFe. Additionally, when using a synthetic pinned layer, further improvement is achieved by using boron doped CoFe for the two antiparallel layers.Type: GrantFiled: September 10, 2002Date of Patent: January 18, 2005Assignee: Headway Technologies, Inc.Inventors: Hui-Chuan Wang, Chyu-Jiuh Torng, Yun-Fei Li
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Publication number: 20040075960Abstract: Although it is known that exchange bias can be utilized in abutted junctions for longitudinal stabilization, a relatively large moment is needed to pin down the sensor edges effectively. Due to the inverse dependence of the exchange bias on the magnetic layer thickness, a large exchange bias has been difficult to achieve by the prior art. This problem has been solved by introducing a structure in which the magnetic moment of the bias layer has been approximately doubled by pinning it from both above and below through exchange with antiferromagnetic layers. Additionally, since the antiferromagnetic layer is in direct abutted contact with the free layer, it acts directly to help stabilize the sensor edge, which is an advantage over the traditional magnetostatic pinning that had been used.Type: ApplicationFiled: October 22, 2002Publication date: April 22, 2004Applicant: Headway Technologies, Inc.Inventors: Yun-Fei Li, Hui-Chuan Wang, Chyu-Jiuh Torng, Cherng-Chyi Han, Mao-Min Chen
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Publication number: 20040047086Abstract: Prior art gains in GMR ratio resulting from use of NiFeCr as a seed layer were offset by the resulting high values obtained for Hc and Hk. This problem has been overcome by combining a seed layer of NiCr or NiFeCr with a free layer of boron doped CoFe. Additionally, when using a synthetic pinned layer, further improvement is achieved by using boron doped CoFe for the two antiparallel layers.Type: ApplicationFiled: September 10, 2002Publication date: March 11, 2004Applicant: Headway Technologies, Inc.Inventors: Hui-Chuan Wang, Chyu-Jiuh Torng, Yun-Fei Li
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Publication number: 20030189801Abstract: In magnetic read heads based on bottom spin valves the preferred structure is for the longitudinal bias layer to be in direct contact with the free layer. Such a structure is very difficult to manufacture. The present invention overcomes this problem by introducing an extra layer between the bias electrodes and the free layer. This layer protects the free layer during processing but is thin enough to not interrupt exchange between the bias electrodes and the free layer. In one embodiment this is a layer of copper about 5 Å thick and parallel exchange is operative. In other embodiments ruthenium is used to provide antiparallel exchange between the bias electrode and the free layer. A process for manufacturing the structure is also described.Type: ApplicationFiled: April 5, 2002Publication date: October 9, 2003Applicant: Headway Technologies, Inc.Inventors: Moris Dovek, Po-Kang Wang, Chen-Jung Chien, Chyu-Jiuh Torng, Yun-Fei Li
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Publication number: 20030179517Abstract: Patterned, longitudinally and transversely antiferromagnetically exchange biased GMR sensors are provided which have narrow effective trackwidths and reduced side reading. The exchange biasing significantly reduces signals produced by the portion of the ferromagnetic free layer that is underneath the conducting leads while still providing a strong pinning field to maintain sensor stability. In the case of the transversely biased sensor, the magnetization of the free and biasing layers in the same direction as the pinned layer simplifies the fabrication process and permits the formation of thinner leads by eliminating the necessity for current shunting.Type: ApplicationFiled: March 22, 2002Publication date: September 25, 2003Applicant: Headway Technologies, Inc.Inventors: Cheng T. Horng, Min Li, Ru-Ying Tong, Yun-Fei Li, You Feng Zheng, Simon Liao, Kochan Ju, Cherng Chyi Han
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Publication number: 20030167625Abstract: A problem associated with current bottom spin valve designs is that it is difficult to avoid magnetic charge accumulation at the edge of the sensor area, making a coherent spin rotation during sensing difficult to achieve. This problem has been eliminated by introducing an exchange coupling layer between the free layer and the ferromagnetic layer that is used to achieve longitudinal bias for stabilization and by extending the free layer well beyond the sensor area. After all layers have been deposited, the read gap is formed by etching down as far as this layer. Since it is not critical exactly how much of the biasing layers (antiferromagnetic as well as ferromagnetic) are removed, the etching requirements are greatly relaxed. Whatever material remains in the gap is then oxidized thereby providing a capping layer as well as a good interface for specular reflection in the sensor region.Type: ApplicationFiled: March 6, 2002Publication date: September 11, 2003Applicant: Headway Technologies, Inc.Inventors: Yun-Fei Li, Hui-Chuan Wang, Chyu-Jiuh Torng, C.C. Han
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Publication number: 20030072970Abstract: In magnetic recording applications, the continuing reduction of transducer dimensions has created a need for soft magnetic thin films with magnetic moments greater than about 22 kG are required. The present invention achieves this by use of a laminated structure made up of a thin layer of a high magnetic moment material on a layer of soft magnetic or non-magnetic material, both layers having very similar crystal structures and chemical composition, the main difference being in their nitrogen content. Such a laminate has been found to have the required high magnetic moment as well as low coercivity. The laminate is used to improve the characteristics and performance of a write head by being inserted at one or both sides of the write gap. Alternatively, the magnetic poles of the head may be constructed entirely from multiple instances of the laminate. A process for forming the laminate and applying it to the write head is also described.Type: ApplicationFiled: October 5, 2001Publication date: April 17, 2003Applicant: Headway Technologies, Inc.Inventors: Yun-Fei Li, Hui-Chuan Wang, Chyu-Jiuh Torng