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Method for Patterning Self-aligned Rear Flux Guide

IP.com Disclosure Number: IPCOM000013619D
Original Publication Date: 2000-Dec-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 3 page(s) / 46K

Publishing Venue

IBM

Abstract

In magnetoresistive(MR) read heads for hard disk drives, the sensitivity of the heads is limited by several factors. These factors include the magnetoresistive characteristics of the material, the gap/shield structure details, the fly height, and the stabilization scheme. One other factor which limits sensistivity is the fact that the entire MR region does not typically rotate in response to the applied field from the disk. One method to enhance the rotation of the MR region is to add a rear flux guide(RFG) layer behind the MR.(figure 1) Figure 1 Position of RFG relative to MR sensor Shield 2 Gap 2

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Method for Patterning Self-aligned Rear Flux Guide

   In magnetoresistive(MR) read heads for hard disk drives, the sensitivity of the heads is limited by several factors. These factors include the magnetoresistive characteristics of the material, the gap/shield structure details, the fly height, and the stabilization scheme. One other factor which limits sensistivity is the fact that the entire MR region does not typically rotate in response to the applied field from the disk. One method to enhance the rotation of the MR region is to add a rear flux guide(RFG) layer behind the MR.(figure 1)

Figure 1 Position of RFG relative to MR sensor

Shield 2

Gap 2

MR Sensor

RFG

One possible method for depositing and patterning a RFG structure is shown in Figures 2 and 3. Figure 2 shows a standard method for definining stripe height on a wafer. Figure 3 shows how the RFG material can be deposited just after the ion milling which defines the stripe pattern. In this way the RFG layer is self aligned to the MR free layer, causing excellent magnetic coupling between them.

Figure 2 Standard Patterning Process for Stripe Height Definition

Gap 1

Shield 1

Wafer Stripe Dimension(~3um)

Liftoff Photoresist Structure

Patterned MR Layer

Gap 1 Shield 1

Figure 3 Deposition of Rear Flux Guide Material

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Flux Guide Layer Deposition

     After the RFG is deposited, it is necessary to define its rear boundary. This is because the RFG contacts both leads and is likely to be made of a conducting material. Any current carried by the RFG will produce very little signal amplitude and will shunt current that would otherwise flow through the sensor. Therefore, long RFG dimensions will tend to produce sensors with less sensitivity.

     One way to define the RFG rear boundary is shown in figure 4. The photoresist which defined the MR rear boundary has been removed, and a new photoresist layer has been applied and patterned. In this case, ion milling is used to remove the unwanted RFG material. This...