Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2000-04-05
2001-06-26
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S192120, C204S192220, C204S192230, C427S131000
Reexamination Certificate
active
06251231
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an MR (Magneto-Resistive) head which reads information written on a magnetic recording medium with an MR element (Magneto-Resistive element), and a manufacturing process for it.
2. Description of the Prior Art
In general, an MR head has a structure in which magnetic shielding films are disposed on and under an MR element (magnetic sensitive section) through magnetic gap films to effectively accept leakage flux from a magnetic recording medium. In addition, an MR head is formed on a wafer, cut out and ground to expose the MR element on a surface opposite to the magnetic recording medium, thereby detecting the leakage flux from the magnetic recording medium. Moreover, Japanese Patent Application Laid-Open No. 8-293108 discloses an invention which uses a film with ability to withstand high voltage having a thickness 30 nm or less as a magnetic separating film between a soft magnetic film and an MR film of a magneto-resistive head. Furthermore, Japanese Patent Application Laid-Open Nos. 8-221721 and 8-167123 disclose an invention, wherein, in forming a magneto-resistive head element and a recording/reproduction separated combination head element, the element is prevented from dielectric breakdown due to static electricity during the process by short-circuiting a pair of electrodes constituting the magneto-resistive head, thereby forming the element with a high yield.
BRIEF SUMMARY OF THE INVENTION
An MR element in an MR head has a problem that it tends to be dielectrically broken because it consists of very thin films. In addition, thickness is about 250-300 nm for upper and lower magnetic shield films of the MR head and magnetic gap films of the MR element, so that dielectric breakdown tends to occur due to steps in the electrodes or the like. It is anticipated that dielectric voltage is further lowered because the insulating film is made to have a thinner thickness to accommodate a narrower track and a narrower gap which are necessary for higher density.
However, a magnetic gap film consisting of Al
2
O
3
discussed in Japanese Patent Application Laid-Open Nos. 62-214507 and 63-16408 cannot assure sufficient dielectric voltage for a thin film with thickness of 1,000 Angstrom or less, so that it is difficult to be thinned. In addition, if an alumina film has a high stress value, weak area in the film arises. Such a weak area can be easily chemical-etched when the film is thinned, leading to degradation of the film or causing a lower dielectric voltage.
OBJECT OF THE INVENTION
An object of the present invention is to provide an MR head which can stably supply a magnetic gap film accommodating a narrower gap, and a manufacturing process for it.
SUMMARY OF THE INVENTION
The present invention is an MR head comprising a read element, the reproduction head consisting of two opposite magnetic shield films, two opposite magnetic gap films held between the two magnetic shield films, and an MR element held between the two magnetic gap films, wherein a stress value of the magnetic gap film is 200 MPa or less. It may be an MR head comprising a recording (writing) head and a read element (reproduction head) the recording head comprising a coil held between two opposite magnetic poles through an inter-layer insulating film, and a recording gap provided at an end between the two opposite magnetic poles, the recording head and the read element being laminated, one of the two magnetic shield films also serving as one of the two magnetic poles, wherein a stress value of the magnetic gap film is 200 MPa or less. In addition, the magnetic gap film may be an insulating film mainly consisting of Al
2
O
3
, or an insulating film mainly consisting of Al
2
O
3
and SiO
2
(preferably, 30 wt. % or more being contained in the entire volume).
A manufacturing process for MR head according to the present invention comprises the step of forming the (said) magnetic gap film by sputtering a target of Al
2
O
3
or Al
2
O
3
and SiO
2
in a mixed gas of Ar and O
2
. In this case, it is preferable to form the magnetic gap film at a sputter power of 6 W/cm
2
or more.
Lowering stress in the magnetic gap film reduces pinhole density in the film, so that the insulating performance of the film is improved. It has been found that the stress in the magnetic gap film can be further reduced by adding SiO
2
in the alumina target, or mixing oxygen in Ar gas in the sputtering step. Thus, improvement of dielectric voltage of the magnetic gap film can prevent so called dielectric breakdown that the MR element is broken as over-voltage is applied.
REFERENCES:
patent: 5668685 (1997-09-01), Soeya et al.
patent: 5870262 (1999-02-01), Ikegawa et al.
patent: 62-214507 (1987-09-01), None
patent: 63-16408 (1988-01-01), None
patent: 3-64451 (1991-03-01), None
patent: 5-274626 (1993-10-01), None
patent: 8-77514 (1996-03-01), None
patent: 8-167123 (1996-06-01), None
patent: 8-221721 (1996-08-01), None
patent: 8-293108 (1996-11-01), None
patent: 9-161237 (1997-06-01), None
patent: 10-40517 (1998-02-01), None
Saito Mikiko
Suzuki Fujio
McDonald Rodney G.
NEC Corporation
Young & Thompson
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