Browse Prior Art Database

Dual Layer Overcoat

IP.com Disclosure Number: IPCOM000013482D
Original Publication Date: 2001-Aug-01
Included in the Prior Art Database: 2003-Jun-18
Document File: 2 page(s) / 94K

Publishing Venue

IBM

Abstract

Disclosed is a new overcoat process on wafer level. The modification allows reducing significantly the amount of redeposited metallic material. Especially copper redeposition in the pole zone may act as a starting point for corrosion or may lead to copper protrusion. Redeposition is caused by pre sputter etching and occurs on surfaces where the etching rate is less compared to the deposition rate of previously removed material. Typically, this occurs at the sidewalls of pronounced features of a surface.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 58% of the total text.

Page 1 of 2

Dual Layer Overcoat

  Disclosed is a new overcoat process on wafer level. The modification allows reducing significantly the amount of redeposited metallic material. Especially copper redeposition in the pole zone may act as a starting point for corrosion or may lead to copper protrusion. Redeposition is caused by pre sputter etching and occurs on surfaces where the etching rate is less compared to the deposition rate of previously removed material. Typically, this occurs at the sidewalls of pronounced features of a surface.

  Here a dual layer overcoat process is described to overcome redeposition issues. The first overcoat is thin and reactively sputtered and can be deposited without a presputter etch. This avoids redeposition below the overcoat 1. Furthermore, overcoat 1 covers all metallic material including copper. Overcoat 2 is deposited including an intense sputter etch step. In contrast to the situation before, the redeposited material is no more metallic but alumina. Therefore the visible redeposition vanishes completely or is reduced significantly. An overcoat made of alumina (Al2O3) is used for packaging of magnetic read write heads. The alumina coats mechanically and chemically sensitive structures like the pole tips and copper leads. These structures are not planar but show strong topography including perpendicular walls. During a sputter etch step, most likely, redeposited copper will contaminate the surface left and right of the poletip. Indeed, copper...