Fabrication of spintronic devices - Etching endpoint detection by resistance measurement for magnetic tunnel junctions

Abstract

Magnetic tunnel junctions (MTJs) have received tremendous interest since the discovery of substantial room temperature tunneling magnetoresistance (TMR) due to spin-dependent tunneling, and have been intensively investigated for applications in next-generation memory devices, hard disk drives, and magnetic sensors. In the fabrication of MTJs, etching is needed to remove the top cap layers, upper magnetic layers, and the middle oxide layer in order to form a tunneling junction. In view of this, we have devised an innovative, simple, low-cost endpoint detection method for fabricating MTJs. In this method, the endpoint is detected by measurement of the sheet resistance of the MTJ stack. Only a multimeter is needed in this method, hence it provides a simple low-cost alternative for spintronic device researchers to explore the research field of magnetic tunnel junctions. This technique is also of great use in other kinds of metallic stack etching experiments.