Headway Technologies, Incorporated

You Feng Zheng

Kochan Ju

Simon H Liao

Min Li

Cheng Tzong Horng

Mao-Min Chen

Cherng-Chyi Han

Ru Ying Tong

Charles H Lin

Ru-Ying Tong

Yun-Fei Li

Cherng Chyi Han

Rod Lee

A patterned, synthetic, longitudinally exchange biased GMR sensor is provided which has a narrow effective trackwidth and reduced side reading. The advantageous properties of the sensor are obtained by satisfying a novel relationship between the magnetizations (M) of the ferromagnetic free layer (F1) and the ferromagnetic biasing layer (F2) which enables the optimal thicknesses of those layers to be determined for a wide range of ferromagnetic materials and exchange coupling materials. The relationship to be satisfied is M/M=(J+J)/J, where Jis the synthetic coupling energy between F1 and F2 and Jis the exchange energy between F2 and an overlaying antiferromagnetic pinning layer. An alternative embodiment omits the overlaying antiferromagnetic pinning layer which causes the relationship to become M/M=1.

Synthetic pattern exchange configuration for side reading reduction

A magnetic read head with reduced side reading characteristics is described. This design combines use of a current channeling layer (CCL) with stabilizing longitudinal bias layers whose magnetization direction is canted relative to that of the free layer easy axis and that of the pinned layer (of the GMR). This provides several advantages: First, the canting of the free layer at the side region results in a reduction of side reading by reducing magnetic sensitivity in that region. Second, the CCL leads to a narrow current flow profile at the side region, therefore producing a narrow track width definition. A process for making this device is described. Said process allows some of the requirements for interface cleaning associated with prior art processes to be relaxed.

Biased spin valve head with canted adjacent layer and current channeling layer

A patterned, synthetic, longitudinally exchange biased GMR sensor is provided which has a narrow effective trackwidth and reduced side reading. The advantageous properties of the sensor are obtained by satisfying a novel relationship between the magnetizations (M) of the ferromagnetic free layer (F) and the ferromagnetic biasing layer (F) which enables the optimal thicknesses of those layers to be determined for a wide range of ferromagnetic materials and exchange coupling materials. The relationship to be satisfied is M/M=(J+J)/J, where Jis the synthetic coupling energy between Fand Fand Jis the exchange energy between Fand an overlaying antiferromagnetic pinning layer. An alternative embodiment omits the overlaying antiferromagnetic pinning layer which causes the relationship to become M/M=1.

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.

Method for fabricating a patterned synthetic longitudinal exchange biased GMR sensor

As the dimensions of spin valve heads continue to be reduced, a number of difficulties are being encountered. One such is with the longitudinal bias when an external magnetic field can cause reversal of the hard magnet, thereby causing a hysteric response by the head. This coercivity reduction becomes more severe as the hard magnet becomes thinner. This problem has been overcome by inserting a decoupling layer between the antiferromagnetic layer that is used to stabilize the pinned layer of the spin valve itself and the soft ferromagnetic layer that is used for longitudinal biasing. This soft ferromagnetic layer is pinned by a second antiferromagnetic layer deposited on it on its far side away from the first antiferromagnetic layer. The presence of the decoupling layer ensures that the magnetization of the soft layer is determined only by the second antiferromagnetic layer. The inclusion of said decoupling layer allows more latitude in etch depth control during manufacturing.

Ferromagnetic/antiferromagnetic bilayer, including decoupler, for longitudinal bias

Process of manufacturing a magnetic read head

As the dimensions of spin valve heads continue to be reduced, a number of difficulties are being encountered. One such is with the longitudinal bias when an external magnetic field can cause reversal of the hard magnet, thereby causing a hysteric response by the head. This coercivity reduction becomes more severe as the hard magnet becomes thinner. This problem has been overcome by inserting a decoupling layer between the antiferromagnetic layer that is used to stabilize the pinned layer of the spin valve itself and the soft ferromagnetic layer that is used for longitudinal biasing. This soft ferromagnetic layer is pinned by a second antiferromagnetic layer deposited on it on its far side away from the first antiferromagnetic layer. The presence of the decoupling layer ensures that the magnetization of the soft layer is determined only by the second antiferromagnetic layer. The inclusion of the decoupling layer allows more latitude in etch depth control during manufacturing.

Spin valve heads with overlaid leads have several advantages over butted contiguous junction designs, including larger signal output and better head stability. However, in any overlaid design there is always present at least one high resistance layer between the GMR layer and the conductive leads. This leads to an effective read width that is greater than the actual physical width. This problem has been overcome by inserting a highly conductive channeling layer between the GMR stack and the conducting lead laminate. This arrangement ensures that, at the intersection between the leads and the GMR stack, virtually all the current moves out of the free layer into the leads thereby providing an effective read width for the device that is very close to the physical read width defined by the spacing between the two leads. A process for manufacturing the device is also described.

Spin valve head with a current channeling layer

An improved stabilization scheme for a GMR read head is described. Two important changes relative to prior art designs have been introduced. Instead of biasing by means of a permanent magnet or through exchange coupling with an antiferromagnetic layer, the magnetostatic field emanating from a nearby, but not contiguous, layer is used. Additionally, to obtain optimum stability with this scheme the bias, instead of running parallel to the easy axis of the free layer, is canted away from it towards the direction of the demagnetizing field of the pinned layer. A process for the manufacture of the structure is also described.

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San Jose, CA, United States of America

You Feng Zheng