How Does Electrostatic Discharge Event Not Cause Polarity Flip in TMR Read Heads?

Abstract

Electrostatic Discharge (ESD) current causes both hard and soft failures on GMR read head technology; however, the current head technology such TMRs, the soft failure phenomenon such magnetization reversal has not been well understood. The previous published work only states that the soft failure does not occur on TMR technology; however none has pinpointed the cause of it. This work for the first time thoroughly explain the mechanism why ESD current does not cause a magnetization reversal on TMR read head instead ESD event likely induces only hard failure on TMRs. The explanation of this mechanism was conducted by investigating the important parameters such as Blocking Temperature (TB), Neel Temperature (TN), Curie Temperature (TC), and Electric Field Breakdown (EB) of a particular TMR head were monitored while an ESD current being applied by using Finite Element simulator. The results reveal that the oxide breakdown at the insulator layer occurs at a lower level of ESD current; for example this particular TMR head the oxide breakdown occurs at ESD peak current of 4 mA while it requires 6 mA to causes a magnetization reversal.