The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 27, 2008
Filed:
Apr. 20, 2004
Chao-peng Chen, Fremont, CA (US);
Rina Kaji, Tokyo, JP;
Jei-wei Chang, Cupertino, CA (US);
Headway Technologies, Inc., Milpitas, CA (US);
TDK Corporation, Tokyo, JP;
Abstract
A method for forming a big-layer lift-off mask for use in fabricating GMR read-head sensors with trackwidths of less than 0.1 microns. The mask layers are formed symmetrically on each other, each layer of the mask having a novel dog-bone shape and the lower mask layer being substantially undercut relative to the upper mask layer. The central portion of the lower mask layer forms a narrow ridge that maintains the upper mask layer at a fixed height above a substrate, thereby avoiding problems associated with big-layer lift-off masks of the prior art. The method of forming the lower ridge requires a carefully controlled undercutting of the lower mask layer, which is accomplished by using an ozone-assisted oxidation process.