A comparison of quasi-static characteristics and failure signatures of GMR heads subjected to CDM and HBM ESD events

Abstract

The effects of the human body model (HBM) electrostatic discharge (ESD) waveform on giant magnetoresistive (GMR) heads is fairly well characterized. This information provides a baseline against which a comparison can be made for other ESD models. The goal of this work is to compare and contrast the effects that are seen in GMR sensors when they are subjected to the charged-device model (CDM) versus HBM ESD events. This study compares the effects of CDM waveforms versus HBM waveforms on a single design of MR head. Although the HBM waveform has provided a starting point for understanding ESD damage to GMR heads, it is believed that the CDM model has a more useful basis in the reality of head manufacturing. This makes study of the effects of CDM ESD events on GMR heads both important and interesting. Detailed characterization of head response as a function of the ESD waveform was realized using a new system combining quasi-static (QST) analysis with in-situ CDM and HBM ESD simulation capabilities. A SEM was used to perform failure analysis on damaged heads in an attempt to characterize differences in the "failure signature" of the sensor.