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Shaping of magnetic pieces via ion implantation

IP.com Disclosure Number: IPCOM000015752D
Original Publication Date: 2002-Sep-01
Included in the Prior Art Database: 2003-Jun-21
Document File: 3 page(s) / 219K

Publishing Venue

IBM

Abstract

Present thin film head write pole tips are 'notched' to improve the localization of the head field and thus produce a written transition width, i.e., trackwidth, dimension which is close to the physical P2, or top yoke, dimension. A notched head is formed by removing P1, or bottom pole piece, material, typically via ion milling using the P2 material as a mask. An undesirable effect of this process is that it also removes material from P2 and this thickness reduction reduces the efficiency of the write head. This invention describes an alternative technique to create effective "notches" in pole pieces using ion implantation. The P1 material is not removed but rather ion implanted to reduce the moment of the material locally. This process provides for minimum thickness reduction of the P2 pole tip. The 'notching' process and the physics of 'notching' are shown schematically below. Notching is a process in which the top pole, P2, trackwidth dimension is transferred into the bottom pole, P1, layer. The trackwidth dimension is transferred using ion milling with the top P2 structure being a mask. As shown above, after the P2 shape is plated, the resist is removed and the seedlayer is etched. Then ion milling is used to remove the gap and the P1 material. During this milling process, the P2 1

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Shaping of magnetic pieces via ion implantation

    Present thin film head write pole tips are 'notched' to improve the localization of the head field and thus produce a written transition width, i.e., trackwidth, dimension which is close to the physical P2, or top yoke, dimension. A notched head is formed by removing P1, or bottom pole piece, material, typically via ion milling using the P2 material as a mask. An undesirable effect of this process is that it also removes material from P2 and this thickness reduction reduces the efficiency of the write head. This invention describes an alternative technique to create effective "notches" in pole pieces using ion implantation. The P1 material is not removed but rather ion implanted to reduce the moment of the material locally.

This process provides for minimum thickness reduction of the P2 pole tip. The 'notching' process and the physics of 'notching' are shown schematically below.

Notching is a process in which the top pole, P2, trackwidth dimension is transferred into the bottom pole, P1, layer. The trackwidth dimension is transferred using ion milling with the top P2 structure being a mask. As shown above, after the P2 shape is plated, the resist is removed and the seedlayer is etched. Then ion milling is used to remove the gap and the P1 material. During this milling process, the P2

1

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structure is consumed. This reduction in P2 thickness, Dn, reduces the write efficiency of the head

The direct result of notching is a more localized write width for the written magnetic transition. This occurs because the fringing fields from the P2 no longer terminate on the flat P1 surface but on the side walls of the notched region of P1. As shown above, if a notch depth of one gap thickness, 1g, is achieved, the fringing field width from the edge of P2 is reduced from 2g to 1g. In a narrow head environment, with a trackwidth of 0.20 um and a read gap of 0.05 um, the fringing fields in an unnotched head could increase the written trackwidth to 0.40 um while a notched head would have a written trackwidth below 0.30 um.

We describe an alternative technique to create effective "notches" in pole pieces using ion implantation. The regions which have been implanted with ions have magnetic Curie temperatures below zero centigrade, i.e. are paramagnetic at room temperature. As such they provide a poor path for magnetic flux, that is to say that the ion implanted region has low permeability, and thus the implanted regions allow the fringe fields to close not on the top surface of the P1 layer but on the unimplanted side walls of the P1 material below the P2 pole tip just as in the case when notches are created by material removal. The species of ion, and its dose, must be chosen by consideration of its chemical influence on the P1 material. For example, the introduction of Cr into NiFe alloy systems is known to depress the Curie temperatu...