Magneto-resistive type magnetic head with a shunt layer of molybdenum

#The present invention relates to a magneto-resistive head with a shunt layer. More particularly, the present invention relates to a magneto-resistive head with a shunt layer having a substantially reduced gap length and having good heat resistance and good corrosion resistance.

#A magneto-resistive head (hereinafter MR head) is used in a hard disk drive of a computer or a signal recording and reproducing apparatus, such as, for example, a video tape recorder. The MR head has good characteristics for reproducing a signal.

#The MR head is a magnetic head using a magneto-resistive layer (hereinafter MR device). The MR device has characteristics in which the electric resistance thereof changes in accordance with a magnetic field adjacent to the MR device. Therefore, as the magnetic field adjacent to the MR device in the MR head changes in response to a signal recorded on a magnetic medium, the MR head provides a reproducing signal which is proportional to the resistance change of the MR device.

#FIG. 1 is a cross section view showing a first embodiment of the present invention.

#FIG. 2 is a perspective view showing a first step of a manufacturing process used to fabricate the first embodiment of the present invention.

#FIG. 3 is a perspective view showing a second step of the manufacturing process.

#FIG. 1 shows the structure of a first embodiment of the present invention from a cross sectional view. The MR head 100 includes a base 102 illustratively made of Al.sub.2 O.sub.3 --TiC, an insulation layer 104 illustratively made of Al.sub.2 O.sub.3, a lower shield layer 106 made of, for example, NiFe, a lower insulation layer 108, an MR layer 110 made of NiFe, electrode layers 112, each of which is composed of layers of Molybdenum (Mo), Gold (Au) and Mo, a shunt layer 114 made of Mo, an upper insulation layer 116 and an upper shield layer 118.

#The shunt layer 114 has a thickness on the order of 100 angstrom (.ANG.). Further, the grain size of the Mo that forms the shunt layer 114 is preferably more than 150 angstrom (.ANG.). The term "grain size" as used herein means an average grain size (D) along a direction in a plane of the shunt layer 114. The average grain size (D) may preferably be measured by a method in which a line width of diffraction in plane(1 1 1) by X-ray is measured. This value is applied to Scherrer's formula, as shown below. ##EQU1## wherein k is a wavelength of X-ray, .theta. is a Bragg angle, B is a half value of a measured diffraction line width and b is a distribution of X-ray of the diffraction apparatus.

#The specific resistance value of the shunt layer 114 is illustratively 20 .mu..OMEGA.cm. This value of the specific resistance is substantially low in comparison with that used in prior art. A relatively low specific resistance facilitates in making the thickness of the shunt layer 114 smaller without changing the resistance of the shunt layer 114. A gap length of the MR head 100 is defined by the distance between the upper shield layer 118 and the lower shield layer 108. Since the shunt layer 114 is disposed between the upper shield layer 118 and the lower shield layer, the thickness of the shunt layer 114 effects the gap length of the MR head 100. In other words, if the thickness of the shunt layer 114 is made smaller, the gap length of the MR head 100 is also made smaller. Therefore, using a material having a relatively low specific resistance as the shunt layer is preferable for making the MR head to have a narrow gap length.