JPS6254812A - Thin film magnetic head and its manufacture - Google Patents

Abstract

PURPOSE:To reduce the residual magnetization of a preceding signal caused by track deviation of a magnetic head caused between a recording and reproducing time by forming the cross section of an opposed magnetic substance as a trapezoid opposed to the short side. CONSTITUTION:The cross section of a lower magnetic pole 8 is formed trapezoidal and the cross section of an upper magnetic pole 9 is formed inverse- trapezoid. Thus, a recording and reproducing gap 10 formed between the lower magnetic pole 8 and the upper magnetic pole 9 is wider at both ends 11. When the recording and reproducing gap is large in general in the magnetic recording, no high density recording is desired, but the magnetic flux from the magnetic pole reaches remotely. Thus, in applying re-recording to the area recorded already, a signal is not recorded accurately at both ends 11 of the gap but the magnetic flux reaches the magnetic medium somewhat apart and the signal recorded already is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin film magnetic head, and more particularly to an optical thin film magnetic head suitable for high track density recording and a method for manufacturing the same.

[Conventional technology]

As shown in FIG. 2, the thin film magnetic head has a lower magnetic pole 1.
It is composed of an upper magnetic pole 2 and a coil 3. FIG. 3 is a sectional view of the thin film magnetic head 4 viewed from the direction of arrow A in FIG.
They are facing each other as shown in the diagram. Furthermore, lower magnetic pole 1
The upper magnetic pole 2 and the upper magnetic pole 2 are covered with a protective layer 5 made of the same material as the gap 4.

Conventionally, in this type of thin film magnetic head, the lower magnetic pole 1 and the upper magnetic pole 2 have rectangular cross sections and are arranged in alignment as shown in FIG. When recording signals on a magnetic medium with this thin-film magnetic head, the magnetic field distribution at the magnetic pole tips 6 and 7 is very steep, so there is a difference between a recorded area and an unrecorded area on the magnetic medium. The boundaries were extremely clear.

[Problem that the invention seeks to solve]

Although this property is an advantage in high track density recording, it is also a significant disadvantage in a configuration such as a magnetic disk device in which a magnetic head seeks and reads recorded signals. That is, since magnetic disk drives do not have erasing heads, new signals are recorded over previously recorded signals. At this time, if the recording position of the previous signal and the recording position of the new signal are shifted, a part of the previous signal will remain erased.

For this reason, when a new seek is performed next time and the signal is reproduced, the remaining part of the previous signal may end up being reproduced entirely depending on the degree of shift in the seek position. The seek deviation in current large magnetic disk devices is about ±2 μ. Therefore, if it is assumed that a signal is recorded at a pitch of 10 μ, an error amount, that is, a noise amount, will remain as much as 20 times, and the worst-case signal-to-noise ratio is -14 dB. Magnetic disk drives with large noise tend to cause signal reproduction errors bt, and normal recording and reproduction functions cannot be expected with the 8N ratio as illustrated.

Therefore, it is an object of the present invention to provide a thin film magnetic head that does not increase the amount of unerased data even if there is a seek position shift during recording and reproduction.

[Means for solving problems]

According to the present invention, there is provided a thin film magnetic head characterized in that the cross-sectional shape of the magnetic material facing the recording medium in the direction perpendicular to the gap of the magnetic head and parallel to the recording medium is trapezoidal with the short sides facing each other. It will be done.

Furthermore, according to the present invention, the lower magnetic pole formed on the substrate of the thin film magnetic head has a trapezoidal cross section by creating the magnetic pole width by ion milling, and the upper magnetic pole formed on the upper part is made of photoresist. A method for manufacturing a thin film magnetic head is obtained, which is characterized in that the cross section is made into an inverted trapezoidal shape by electroplating after fully defining the magnetic pole width.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, the lower magnetic pole 8 has a trapezoidal cross section, and the upper magnetic pole 9 has an inverted trapezoidal cross section. Therefore, the recording/reproducing gap 10 formed between the lower magnetic pole 8 and the upper magnetic pole 9 is widened at both ends 11 thereof. In magnetic recording, high-density recording cannot generally be expected if the recording/reproducing gap is large, but the magnetic flux from the magnetic poles can reach a long distance.

Therefore, when re-recording on an area that was previously recorded, the configuration shown in Figure 1 does not allow accurate recording of signals at both ends 11 of the gap, but the magnetic flux reaches the magnetic medium that is a little further away. The recorded signal can be reduced.

FIG. 4 schematically shows the state on the magnetic medium recorded in this manner. When recording the new signal 13 on top of the old signal 12, even if the position of the magnetic pole 14 deviates from the position of the old signal 12, it is possible to erase the old signal 12 as shown in area 15 by the magnetic pole tip. can. If this shift is large, some of the previous signal remains as shown in area 16, but the overall erasing effect is large.

Next, a manufacturing method of an embodiment of the present invention will be described. FIG. 5 shows the manufacturing procedure of the lower magnetic pole. In FIG. 5a, a magnetic film 18 is formed on a substrate 17 by electroplating, sputtering, or vacuum deposition.

Next, as shown in FIG.
9 is arranged by exposure and development, and is further irradiated with argon ions by dry etching such as ion milling or sputter etching. The argon ion etches the magnetic film 18 and the photoresist 19.
T- is also slightly etched. After the etching is completed, the magnetic film becomes a trapezoidal lower magnetic pole 20 with an inclined end as shown in FIG. 5C.

Next, as shown in FIG. 6a, a recording/reproducing gap 21 made of a non-magnetic material with a uniform thickness and a metal base film 22 are placed on the lower magnetic pole 20.
It is formed by T-sputtering or vacuum evaporation. Furthermore, a photoresist 23 is applied thereon, and the portion to become the upper magnetic pole is exposed and developed and removed as shown in FIG. At this time, the edge 24 of the photoresist becomes oblique as shown. Next, a magnetic film is attached to the opening of the metal base film 22 shown in FIG. 6C by electroplating, the photoresist 23 is removed, and the metal base film 22f is removed by dry etching as shown in FIG. 6C. The lower magnetic pole 20 is trapezoidal and the upper magnetic pole 25
A thin film magnetic head having an inverted trapezoidal shape can be obtained.

〔Effect of the invention〕

As explained above, the present invention reduces the residual magnetization of the previous signal caused by the track misalignment of the magnetic head that occurs during recording/reproducing time by making the cross-sectional shape of the opposing magnetic bodies into a trapezoid with the short sides facing each other. can be done.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a thin film magnetic head showing an embodiment of the present invention, FIG. 2 is a plan view of the thin film magnetic head, FIG. 3 is a sectional view of a conventional thin film magnetic head, and FIG. 4 is a sectional view of the thin film magnetic head according to the present invention. FIG. 5 is a diagram illustrating the manufacturing procedure of a lower magnetic pole according to an embodiment of the present invention. FIG. It is a figure which shows the manufacturing procedure of the upper magnetic pole of an Example. 1...Lower magnetic pole, 2...Upper magnetic pole, 3
... Coil, 4 ... Thin film magnetic head,
6, 7...Magnetic end portion, 8...Bottom magnetic pole, 9...Top magnetic pole, 10...Record/reproduction gap, 12......・Old signal, 13...
New signal, 18...Magnetic film, 19...Photoresist, 20...Lower magnetic pole, 21...
...recording/reproducing gap, 22...metal base film, 23...photoresist, 25...
Upper magnetic pole. 7〈-2... Agent Patent attorney Susumu Uchihara (, par) 1ゝgu゛. Figure 1 Sheep 4 b

Claims (2)

[Claims] (1) A thin film magnetic head characterized in that the cross-sectional shape of the two opposing magnetic poles appearing on the medium facing surface is trapezoidal with the short sides facing each other. (2) After carving out the lower magnetic pole to be formed near the substrate from the magnetic film formed on the entire surface of the substrate by dry etching, a non-magnetic film having a uniform thickness is applied on the magnetic pole. , a metal base film is attached on the non-magnetic film, a photoresist is applied and an opening is formed, a magnetic film is attached by electroplating, and the photoresist and the metal base film are removed. A method of manufacturing a thin-film magnetic head, characterized in that an upper magnetic pole is opposed to a lower magnetic pole.