Wet chemical etch process for patterning MRAM magnetic layers

摘要

A three-part etching process is employed to selectively pattern exposed magnetic film layers of a magnetic thin film structure. The magnetic structure to be etched includes at least one bottom magnetic film layer and at least one top film layer which are separated by a tunnel barrier layer. The three-part etching process employs various etching steps that selective removing various layers of the magnetic thin film structure stopping on the tunnel barrier layer. The first etching step selective removes any surface oxide that may be present in the passivating layer that is formed on the top magnetic thin film layer, the second etching step selectively removes portions of the passivating layer and the third etching step selectively removes a portion of the exposed magnetic film layer of the structure stopping on the tunnel barrier layer.