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GMR system called "abc Calibration" for predicting stripe height and controlling KissLap Operations

IP.com Disclosure Number: IPCOM000014917D
Original Publication Date: 2001-Sep-13
Included in the Prior Art Database: 2003-Jun-20

Publishing Venue

IBM

Abstract

Disclosed is a Calibration System for GMR sub-micron track width devices that resolves the non-linear character of the Inverse of Stripe Height versus Resistance relationship: 1/SH f(R), hence allows precise Stripe Height prediction and disposition before and after final Kisslap operation. To meet giant magneto-resistive (GMR) head aerial density requirements, thickness of leads have been reduced to permit thinner total read gaps. This has resulted in current crowding at upper GMR lead junction area. Partial milling process, involving deposition of leads before milling MR stripes, further contributes to current crowding. As a result, GMR resistance change as a function of stripe height, lead resistance (RL), and slope constant (K) which is the product of track width and MR sheet resistance, can no longer be resolved by linear equations. Disclosed is a calibration system comprised of wafer MR devices having two different stripe heights with corresponding resistance measurements together with an intermediate resistance test at the end of a pre-Kisslap stripe height lap operation. The initial height of the two MR stripes are 5.0 and 3.0 microns. These two stripe heights repeat in an alternating pattern from one side of the row to the other, where, at the end of wafer process, resistance measurements are made and passed on for later calibration. A third set of resistance values are supplied at the end of the first lapping process referred to as (BCL).