Effect of reactive ion etching on the exchange coupling between IrMn and NiFe

Abstract

The effect of reactive ion etching on the exchange coupling between an antiferromagnetic material (IrMn) and a ferromagnetic material (NiFe) was investigated. Although IrMn is not reactively etched using oxygen or fluorine based chemistries, these chemistries are shown to reduce the exchange coupling between the IrMn and NiFe films by altering the IrMn film composition. These chemistries also have the effect of increasing the resistivity of the IrMn from ∼200 μohm-cm to >1000 μohm-cm. Reactive ion etching is shown to be a good process for reducing the coupling between IrMn–NiFe bilayers used as freelayers in sheet film spinvalves due to its material selectivity and etch stop capability. This process could be used in the processing of exchange-tab-type readback sensors used for magnetic recording.