Patents by Inventor Noriaki Kasahara
Noriaki Kasahara 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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Publication number: 20050195536Abstract: The thin-film magnetic head of the present invention comprises an MR sensor wherein a first ferromagnetic layer in which a magnetization direction is fixed with respect to external magnetic fields, a non-magnetic intermediate layer, and a second ferromagnetic layer in which a magnetization direction changes with respect to the external magnetic fields are stacked, and wherein a sense current flows substantially parallel to the stacked layer surface.Type: ApplicationFiled: February 28, 2005Publication date: September 8, 2005Applicant: TDK CorporationInventors: Takeo Kagami, Noriaki Kasahara, Kazuki Sato, Takayasu Kanaya
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Patent number: 6886239Abstract: In the method of making a thin-film magnetic head in accordance with the present invention, an electron beam resist is irradiated with electron beams in a state where an electrically conductive member is in contact with a magnetoresistive film. Since the magnetoresistive film electrically connects individual forming positions to be formed with magnetoresistive devices, charges stored near the forming positions upon irradiation with the electron beams can be drawn to the outside by way of the electrically conductive member. As a consequence, the electron beams are less likely to lose their rectilinearity, whereby the writing precision for patterning the magnetoresistive film by electron beam lithography can be improved.Type: GrantFiled: December 4, 2002Date of Patent: May 3, 2005Assignee: TDK CorporationInventors: Noriaki Kasahara, Tsuneo Kagotani, Hitoshi Hatate
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Patent number: 6822837Abstract: A lower electrode layer and a lower metallic layer are formed on a substrate, and a TMR multi-layer film is formed thereon. TMR multi-layer film is made up of a lower ferromagnetic layer, a tunnel barrier layer, an upper ferromagnetic layer, a pinning layer and a capping layer. In a region where a terminal is provided, a dummy lower electrode layer and a dummy lower metallic layer are formed on the substrate, and a dummy film is formed thereon. The dummy film has the same film composition as that of the TMR multi-layer film. For defining a shape of a tunnel joint, the capping layer through a halfway point in the lower ferromagnetic layer are selectively etched. In this etching process, the dummy film is also etched at the same time. In the etching process, a measurement for identifying elements scattered from the TMR multi-layer film and the dummy film is performed so as to control a position at which the etching is to be stopped.Type: GrantFiled: January 10, 2002Date of Patent: November 23, 2004Assignee: TDK CorporationInventors: Noriaki Kasahara, Takeo Kagami
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Patent number: 6792670Abstract: A method is provided for manufacturing a magnetoresistive device substructure. The substructure includes: a TMR element; a bias field inducing layer that covers the TMR element; and a front flux probe layer formed on the bias field inducing layer and introducing a signal flux to the TMR element. In the manufacturing method, the TMR element and a dummy element are first formed. The dummy element has a shape similar to the TMR element and located in a specific position with respect to the TMR element. Next, the bias field inducing layer is formed on the TMR element in a specific position referring to the position of the dummy element. At the same time, a dummy bias field inducing layer is formed in a position located off the dummy element. Next, the front flux probe layer and a dummy front flux probe layer are formed at the same time on the bias field inducing layer and the dummy element, respectively.Type: GrantFiled: March 16, 2001Date of Patent: September 21, 2004Assignee: TDK CorporationInventors: Kazuki Sato, Noriaki Kasahara, Koji Shimazawa
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Publication number: 20040160704Abstract: The present invention provides an MR element bar that permits the fabrication of MR elements in which a variation in characteristics is suppressed, as well as an MR element bar exposure method and formation method enabling the fabrication of the MR element bar. The MR element bar exposure method according to the present invention comprises the steps of: detecting the positions of a plurality of alignment marks P1 to P4 formed on a wafer W; correcting an exposure position correction region R on the basis of the positions of detected alignment marks P1′ to P4′; and exposing a resist which is formed on the wafer W, wherein an MR element bar region B comprises a plurality of MR elements (patterns MRE) aligned in the longitudinal direction of the region B, and one exposure position correction region R is established for one MR element bar region B.Type: ApplicationFiled: August 20, 2003Publication date: August 19, 2004Applicant: TDK CORPORATIONInventors: Tsuneo Kagotani, Hitoshi Hatate, Noriaki Kasahara, Tetsuya Kuwashima, Teruyo Kagotani
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Publication number: 20040061986Abstract: In the thin-film magnetic head of the present invention, the length of each of a pinned layer and an antiferromagnetic layer in their contact area in the depth direction from a surface facing a medium is longer than the length of a free layer in the same direction. When the length of the pinned layer in the depth direction is set longer as such, the direction of magnetization of the pinned layer can be restrained from being tilted by disturbances. Also, the pinned layer and the antiferromagnetic layer have the same length in their contact area in the MR height direction, so that the pinned layer is in contact with the antiferromagnetic layer throughout its length in the MR height direction, thus raising the exchange coupling force, whereby the inclination in the direction of magnetization can be suppressed more effectively.Type: ApplicationFiled: September 2, 2003Publication date: April 1, 2004Applicant: TDK CORPORATIONInventors: Takeo Kagami, Noriaki Kasahara
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Patent number: 6671141Abstract: A ferromagnetic tunnel effective film has a free layer, and a pinned layer and a tunnel barrier layer sandwiched between the free layer and the pinned layer. A bias magnetic field-inductive layer applies a given magnetic field to the free layer, and has its larger width than that of the ferromagnetic tunnel effective film in the bias magnetic field direction. A flux guide layer is stacked with the bias magnetic field-inductive layer, and magnetically combined with the free layer. One end of the flux guide layer constitutes a flux probe portion having its smaller width than that of the bias magnetic field-inductive layer and projecting from the ends of the bias magnetic field-inductive layer.Type: GrantFiled: March 14, 2001Date of Patent: December 30, 2003Assignee: TDK CorporationInventors: Koji Shimazawa, Noriaki Kasahara, Satoru Araki
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Patent number: 6656538Abstract: Provided are a method of manufacturing a magnetoresistive device and a method of manufacturing a thin film magnetic head capable of efficiently forming a magnetoresistive device having an extremely small magnetoresistive film pattern, and capable of reducing variations in dimensions of the magnetoresistive film pattern. Further, provided is a method of forming a thin film pattern capable of efficiently forming a plurality of thin film patterns with different sizes on a same base with accuracy according to the thin film patterns. Electron beam lithography or photolithography is selectively used according to the sizes of patterns to be formed, so while the dimensional accuracy of a portion specifically requiring higher accuracy can be secured, the patterns can be efficiently formed.Type: GrantFiled: October 18, 2002Date of Patent: December 2, 2003Assignee: TDK CorporationInventors: Kazuki Sato, Noriaki Kasahara, Naoki Ohta
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Publication number: 20030182789Abstract: In the method of making a thin-film magnetic head in accordance with the present invention, an alignment mark is electrically connected to a multilayer film which will later become a TMR film. Therefore, when the alignment mark is irradiated with a position correcting electron beam in order to correct a drawing position in the subsequent step of electron beam lithography, electric charges of the electron beam flow into the multilayer film without staying in the alignment mark. As a consequence, the position correcting electron beam does not lose its straightforwardness, whereby the drawing position in electron beam lithography can be corrected accurately.Type: ApplicationFiled: March 6, 2003Publication date: October 2, 2003Applicant: TDK CORPORATIONInventors: Tsuneo Kagotani, Noriaki Kasahara, Hitoshi Hatate, Teruyo Kagotani
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Publication number: 20030137778Abstract: In the method of making a thin-film magnetic head in accordance with the present invention, an electron beam resist is irradiated with electron beams in a state where an electrically conductive member is in contact with a magnetoresistive film. Since the magnetoresistive film electrically connects individual forming positions to be formed with magnetoresistive devices, charges stored near the forming positions upon irradiation with the electron beams can be drawn to the outside by way of the electrically conductive member. As a consequence, the electron beams are less likely to lose their rectilinearity, whereby the writing precision for patterning the magnetoresistive film by electron beam lithography can be improved.Type: ApplicationFiled: December 4, 2002Publication date: July 24, 2003Applicant: TDK CorporationInventors: Noriaki Kasahara, Tsuneo Kagotani, Hitoshi Hatate
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Patent number: 6583967Abstract: A thin-film magnetic head includes: a TMR element; a lower electrode layer and an upper electrode layer for feeding a current used for signal detection to the TMR element; and an insulating layer provided between the lower and upper electrode layers and located adjacent to a side of the TMR element. The thin-film magnetic head further includes: an FFG layer that introduces a signal flux to the TMR element, the FFG layer touching one of the top surfaces of the TMR element and extending from the region in which the TMR element is located to the region in which the insulating layer is located; and a base film located between the FFG layer and the insulating layer and used as a base when the FFG layer is formed.Type: GrantFiled: June 14, 2001Date of Patent: June 24, 2003Assignee: TDK CorporationInventors: Noriaki Kasahara, Koji Shimazawa
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Publication number: 20030082484Abstract: Provided are a method of manufacturing a magnetoresistive device and a method of manufacturing a thin film magnetic head capable of efficiently forming a magnetoresistive device having an extremely small magnetoresistive film pattern, and capable of reducing variations in dimensions of the magnetoresistive film pattern. Further, provided is a method of forming a thin film pattern capable of efficiently forming a plurality of thin film patterns with different sizes on a same base with accuracy according to the thin film patterns. Electron beam lithography or photolithography is selectively used according to the sizes of patterns to be formed, so while the dimensional accuracy of a portion specifically requiring higher accuracy can be secured, the patterns can be efficiently formed.Type: ApplicationFiled: October 18, 2002Publication date: May 1, 2003Applicant: TDK CORPORATIONInventors: Kazuki Sato, Noriaki Kasahara, Naoki Ohta
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Publication number: 20030020467Abstract: Disclosed is a lapping monitor element that is juxtaposed with a magnetic transducer element having a magnetoresistance effect film to determine the lapping position upon lapping the element height of the magnetic transducer element to a predetermined dimension, the lapping monitor element comprising a resistance film to be resistance measured, the resistance film being a metal film of nonmagnetic transition metal or of alloy composed mainly of nonmagnetic transition metal, or a multilayered film where two or more such metal films are laid one upon another, thereby making it possible to extremely stabilize the ELG sensor resistance measured values upon lapping as well as to provide a high accuracy MR height control.Type: ApplicationFiled: July 15, 2002Publication date: January 30, 2003Applicant: TDK CORPORATIONInventors: Noriaki Kasahara, Nozomu Hachisuka, Yasutoshi Fujita
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Patent number: 6469879Abstract: Magneto-resistive tunnel junction head having a tunnel multilayered film with a tunnel barrier layer, a ferromagnetic free layer, and a ferromagnetic pinned layer formed as a sandwich. A magnetic field is applied to the free layer in a longitudinal direction by biasing elements at opposite ends, and a length of the free layer is greater than a length of the pinned layer such that the free layer has portions extending beyond opposite ends of the pinned layer. A head output suitable for ultra-high density recording can be obtained with less reduction of TMR ratio. Selection of the biasing element is flexible. A hard material and also an antiferromagnetic material can be selected and the biasing elements can be disposed on either an upper or lower side of the free layer at a desired distance.Type: GrantFiled: March 2, 2000Date of Patent: October 22, 2002Assignee: TDK CorporationInventors: Olivier Redon, Koji Shimazawa, Noriaki Kasahara, Satoru Araki
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Publication number: 20020135951Abstract: A lower electrode layer and a lower metallic layer are formed on a substrate, and a TMR multi-layer film is formed thereon. TMR multi-layer film is made up of a lower ferromagnetic layer, a tunnel barrier layer, an upper ferromagnetic layer, a pinning layer and a capping layer. In a region where a terminal is provided, a dummy lower electrode layer and a dummy lower metallic layer are formed on the substrate, and a dummy film is formed thereon. The dummy film has the same film composition as that of the TMR multi-layer film. For defining a shape of a tunnel joint, the capping layer through a halfway point in the lower ferromagnetic layer are selectively etched. In this etching process, the dummy film is also etched at the same time. In the etching process, a measurement for identifying elements scattered from the TMR multi-layer film and the dummy film is performed so as to control a position at which the etching is to be stopped.Type: ApplicationFiled: January 10, 2002Publication date: September 26, 2002Applicant: TDK CORPORATIONInventors: Noriaki Kasahara, Takeo Kagami
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Patent number: 6381107Abstract: In the present invention, a common lead and shield layer is used so as to be electrically contacted with a tunnel multilayered film for supplying a sense current to the tunnel multilayered film. The common lead and shield layer extends to a rear portion of the tunnel multilayered film from an ABS (Air Bearing Surface) so that a part of the common lead and shield layer located at the rear portion of the tunnel multilayered film serves as a back flux guide for improving a read output. Therefore, a lead gap can be remarkably reduced to easily achieve the high-density recording. Further, a large and stable head output suitable for the ultra-high density recording can be obtained with an improved biasing efficiency.Type: GrantFiled: March 2, 2000Date of Patent: April 30, 2002Assignee: TDK CorporationInventors: Olivier Redon, Koji Shimazawa, Noriaki Kasahara, Satoru Araki
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Patent number: 6344954Abstract: The present invention relates to a magneto-resistive tunnel junction head having a tunnel multilayered film composed of a tunnel barrier layer, and a ferromagnetic free layer and a ferromagnetic pinned layer formed to sandwich the tunnel barrier layer therebetween, wherein the ferromagnetic free layer comprises, in an integral fashion, a free layer main portion substantially constituting a part of the tunnel multilayered film, a front flux guide portion extending on a front side of the free layer main portion, and a back flux guide portion extending on a back side thereof, wherein the front flux guide portion constitutes a part of an ABS (Air Bearing Surface), and wherein a width-direction length Lm of the free layer main portion is set greater than a width-direction length Lf of the front flux guide portion and a width-direction length Lb of the back flux guide portion.Type: GrantFiled: March 2, 2000Date of Patent: February 5, 2002Assignee: TDK CorporationInventors: Olivier Redon, Koji Shimazawa, Noriaki Kasahara, Satoru Araki
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Publication number: 20020001158Abstract: A thin-film magnetic head comprises: a TMR element; a lower electrode layer and an upper electrode layer for feeding a current used for signal detection to the TMR element; and an insulating layer provided between the lower and upper electrode layers and located adjacent to a side of the TMR element. The thin-film magnetic head further comprises: an FFG layer that introduces a signal flux to the TMR element, the FFG layer touching one of the top surfaces of the TMR element and extending from the region in which the TMR element is located to the region in which the insulating layer is located; and a base film located between the FFG layer and the insulating layer and used as a base when the FFG layer is formed.Type: ApplicationFiled: June 14, 2001Publication date: January 3, 2002Applicant: TDK CorporationInventors: Noriaki Kasahara, Koji Shimazawa
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Publication number: 20010055184Abstract: A ferromagnetic tunnel effective film has a free layer, and a pinned layer and a tunnel barrier layer sandwiched between the free layer and the pinned layer. A bias magnetic field-inductive layer applies a given magnetic field to the free layer, and has its larger width than that of the ferromagnetic tunnel effective film in the bias magnetic field direction. A flux guide layer is stacked with the bias magnetic field-inductive layer, and magnetically combined with the free layer. One end of the flux guide layer constitutes a flux probe portion having its smaller width than that of the bias magnetic field-inductive layer and projecting from the ends of the bias magnetic field-inductive layer.Type: ApplicationFiled: March 14, 2001Publication date: December 27, 2001Inventors: Koji Shimazawa, Noriaki Kasahara, Satoru Araki
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Publication number: 20010028068Abstract: A magnetoresistive device substructure includes: a TMR element; a bias field inducing layer that covers the TMR element; and a front flux probe layer formed on the field inducing layer and introducing a signal flux to the TMR element. The substructure further includes: a dummy element; a dummy bias field inducing layer; and a dummy front flux probe layer. The dummy field inducing layer is located off the position of the dummy element. Alignment of the dummy field inducing layer and the dummy element allows alignment of the TMR element and the field inducing layer.Type: ApplicationFiled: March 16, 2001Publication date: October 11, 2001Applicant: TDK CORPORATIONInventors: Kazuki Sato, Noriaki Kasahara, Koji Shimazawa