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Improved fabrication method for chevron-type MR sensor

IP.com Disclosure Number: IPCOM000014545D
Original Publication Date: 2000-Feb-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Abstract

In fabricating chevron-type MR sensors for tape heads, normally a photo process is first used to produce a desired chevron pattern. An ion milling process is then used to transfer the pattern into an Al2O3 underlayer. One problem associated with this practice is that the developer used in the photo process attacks Al2O3 chemically. As a result, before the ion milling process, there is already a depth variation due to the developer etch of Al2O3. The problem is also aggravated by the frequent use of photo rework in which Al2O 3 is further attacked. The chevron depth variation can be a contributor to the fluctuation of MR sensor performance. This invention solves the problem by using a spin-on protection layer before the application of the photo resist. The spin-on layer is a thin polymer coating (500 1500 angstroms) that does not dissolve in a photo developer. In the photo lithography process, this layer protects the underlying Al2O3 from developer attack. This protection layer is also used when rework is necessary so that no Al2O3 loss occurs even when multiple reworks are performed. Following the photo lithography patterning process, a selective dry etch step is applied to remove the polymer protection layer from the Al2O3 surface. The etching can be an oxygen reactive-ion-etch process, an oxygen reactive ion beam process, or a chemical-assisted ion beam process using oxygen as the chemical species. Since this etching is selective, the polymer layer can be removed completely with an aggressive overetch without etching the underlying Al2O3. When an ion beam process is used, the polymer etching can be inserted right before the Al2O3 milling for chevron definition in the same processing chamber. 1

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Improved fabrication method for chevron-type MR sensor

   In fabricating chevron-type MR sensors for tape heads, normally a photo process is first used to produce a desired chevron pattern. An ion milling process is then used to transfer the pattern into an Al2O3 underlayer. One problem associated with this practice is that the developer used in the photo process attacks Al2O3 chemically. As a result, before the ion milling process, there is already a depth variation due to the developer etch of Al2O3. The problem is also aggravated by the frequent use of photo rework in which Al2O 3 is further attacked. The chevron depth variation can be a contributor to the fluctuation of MR sensor performance.

This invention solves the problem by using a spin-on protection layer before the application of the photo resist. The spin-on layer is a thin polymer coating (500 - 1500 angstroms) that does not dissolve in a photo developer. In the photo lithography process, this layer protects the underlying Al2O3 from developer attack. This protection layer is also used when rework is necessary so that no Al2O3 loss occurs even when multiple reworks are performed. Following the photo lithography patterning process, a selective dry etch step is applied to remove the polymer protection layer from the Al2O3 surface. The etching can be an oxygen reactive-ion-etch process, an oxygen reactive ion beam process, or a chemical-assisted ion beam process using oxygen as the chemical species. Since...