TMR devices fabricated with RIE etching using CO+NH₃

Abstract

Reactive Ion Etching (RIE) is the most promising technique to realize sub-micron patterns of tunneling magneto-resistance (TMR) junctions for Magnetic Random Access Memory (MRAM) devices. However, it is difficult to be applied into practical use due to re-deposition of the etched material and corrosion by etching gases. In order to eliminate these drawbacks, an etching process utilizing CO + NH₃ gas chemistry and Ta metal mask has been applied. Electron microscopy observations confirmed that there is no re-deposition or corrosion occurs. Using the same process we have succeeded in fabricating a high-quality TMR device that show magneto-resistance (MR) ratio of more than 60 %.